STARCH COMPOSITIONS

Abstract

Provided herein are starch compositions, which comprise a first starch having a first weight average molecular weight between about 300,000 and about 4,000,000 Daltons, a second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons, and a water-soluble polymer. Also provide herein are articles of manufacture and films comprising the starch composition, and methods of making the starch composition.

Claims

1-41. (canceled)

42. A starch composition comprising: a. from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 4,000,000 Daltons; b. from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and c. from about 1% to about 40% by weight of at least one water soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

43. The starch composition according to claim 42, wherein the first starch is present in an amount from about 70% to about 99% by weight, and/or the second starch is present in an amount from about 0.1% to about 35% by weight.

44. The starch composition according to claim 42, wherein the water-soluble polymer is present in an amount from about 3% to about 30% by weight.

45. The starch composition according to claim 42, wherein the water-soluble polymer comprises one or more of polyvinyl alcohol and polyoxyalkylene.

46. The starch composition according to claim 42, wherein the first weight average molecular weight is between about 300,000 and about 3,500,000 Daltons.

47. The starch composition according to claim 42, wherein the second weight average molecular weight is between about 10,000 and about 290,000 Daltons.

48. The starch composition according to claim 47, wherein: a. the second weight average molecular weight is between about 10,000 and about 50,000 Daltons; or b. the second weight average molecular weight is between about 100,000 and about 290,000 Daltons.

49. The starch composition according to claim 42, wherein the molecular weight distribution of the starch composition is greater than 6.5.

50. The starch composition according to claim 42, wherein the amylose content of the first or second starches is, independently, greater than about 10% by weight.

51. The starch composition according to claim 50, wherein the amylose content of the first or second starches is, independently, from about 50% to about 80% by weight.

52. The starch composition according to claim 42, wherein the amylose content of the second starch is less than about 20% by weight.

53. The starch composition according to claim 42, wherein the second starch is a starch which has been treated with an enzyme or with an acid to reduce molecular weight.

54. The starch composition according to claim 42, wherein the modified starch is chemically modified so as to replace hydroxyl functionality with functionality selected from the group consisting of ethers, esters and mixtures thereof.

55. The starch composition according to claim 42, wherein the modified starch is chemically modified to include a hydroxyalkyl C.sub.2-6 group or modified by reaction with an anhydride of a carboxylic acid.

56. The starch composition according to claim 42, wherein the modified starch is chemically modified so as to have a degree of substitution from 0.01 to 1.5.

57. The starch composition according to claim 42, wherein the first starch comprises more than one starches and/or modified starches.

58. The starch composition according to claim 42, wherein the second starch comprises more than one starches and/or modified starches.

59. A film comprising a starch composition according to claim 42.

60. The film according to claim 59, wherein the film has an oxygen permeation coefficient of less than 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% relative humidity (RH), when measured according to ASTM F1927.

61. A method of making a starch composition according to claim 42, the method comprising the step of contacting the first starch, the second starch and the water-soluble polymer under melt processing conditions.

Description

DETAILED DESCRIPTION

[0124] The following is a detailed description of the disclosure provided to aid those skilled in the art in practicing the present disclosure. Those of ordinary skill in the art may make modifications and variations in the embodiments described herein without departing from the spirit or scope of the present disclosure.

[0125] Although any compositions, methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred compositions, methods and materials are now described.

[0126] It must also be noted that, as used in the specification and the appended claims, the singular forms ‘a’, ‘an’ and ‘the’ include plural referents unless otherwise specified. Thus, for example, reference to ‘starch’ may include more than one starches, and the like.

[0127] Throughout this specification, use of the terms ‘comprises’ or ‘comprising’ or grammatical variations thereon shall be taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof not specifically mentioned.

[0128] Unless specifically stated or obvious from context, as used herein, the term ‘about’ is understood as within a range of normal tolerance in the art, for example within two standard deviations of the mean. ‘About’ can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein in the specification and the claim can be modified by the term ‘about’.

[0129] Ranges provided herein are understood to be shorthand for all the values within the range. For example, a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range from the group consisting 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50.

Applications

[0130] The herein disclosed starch compositions may be useful in a variety of applications. For example, the starch compositions may be thermoformed into articles utilizing methods well known in the art. Exemplary thermoformed articles may include trays, containers or lids. The starch compositions may also be useful as components in multilayer films, including, for example, barrier trays for extending the shelf life of perishable foods, including meat, poultry, fish, pasta, small goods, prepared meals and cheese. The starch compositions may also be useful in Modified Atmosphere Packaging (MAP) requiring control of gas permeation.

Multilayer Films

[0131] The herein disclosed starch composition may be useful in the manufacture of a multilayer films. A multilayer film may comprise: [0132] (a) at least one layer comprising a starch composition according to any one of the aspects or embodiments as herein disclosed; and [0133] (b) at least one other layer.

[0134] The at least one other layer may have a water vapour permeability coefficient less than 1 g.mm/m.sup.2.24 hr.atm measured at 38° C. and 90% relative humidity.

[0135] The total thickness of the at least one layer comprising a starch composition may be 20% or greater than the total thickness of the multilayer film.

[0136] The water vapour permeability coefficient of the at least one other layer may be less than 0.5 g.mm/m.sup.2.24 hr.atm measured at 38° C. and 90% relative humidity, or less than 0.2 g.mm/m.sup.2.24 hr.atm measured at 38° C. and 90% relative humidity.

[0137] The total thickness of the at least one layer comprising a starch composition may be 30% or greater than the total thickness of the multilayer film, or 40% or greater than the total thickness of the multilayer film, 50% or greater than the total thickness of the multilayer film. The total thickness of the at least one layer comprising a starch composition may be 60% or greater than the total thickness of the multilayer film.

[0138] The starch layer may have a low oxygen permeability coefficient (OPC). The starch layer may have OPC less than 0.6 cm.sup.3 mm/m.sup.2.24 h.atm at 50% relative humidity (RH). The starch layer may have an OPC of less than 0.3 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH or an OPC of less than 0.2 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH. The starch layer may have an OPC of less than 0.1 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH or the starch layer may have an OPC of less than 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH.

[0139] The starch layer may have an OPC less than 1.2 cm.sup.3 mm/m.sup.2.24 h.atm at 75% relative humidity (RH). The starch layer may have an OPC of less than 0.6 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH or an OPC of less than 0.2 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH. The starch layer may have an OPC of less than 0.1 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH or the starch layer may have an OPC of less than 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH.

[0140] The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH, for extended periods of time. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for at least ten days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for 20 days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for thirty days. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for thirty days.

[0141] The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH, for extended periods of time. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for at least ten days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for 20 days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for thirty days. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for thirty days.

[0142] The multilayer film may have a low oxygen permeability coefficient (OPC). The multilayer film may have an OPC less than 0.6 cm.sup.3 mm/m.sup.2.24 h.atm at 50% relative humidity (RH). The multilayer film may have an OPC of less than 0.3 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH or an OPC of less than 0.2 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH. The multilayer film may have an OPC of less than 0.1 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH or the multilayer film may have an OPC of less than 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH.

[0143] The multilayer film may have an OPC less than 1.2 cm.sup.3 mm/m.sup.2.24 h.atm at 75% relative humidity (RH). The multilayer film may have an OPC of less than 0.6 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH or an OPC of less than 0.2 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH. The multilayer film may have an OPC of less than 0.1 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH or the multilayer film may have an OPC of less than 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH.

[0144] The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH, for extended periods of time. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for at least ten days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for 20 days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for thirty days. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 50% RH for thirty days.

[0145] The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH, for extended periods of time. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for at least ten days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for 20 days, or the OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for thirty days. The OPC may remain below 0.05 cm.sup.3 mm/m.sup.2.24 h.atm at 75% RH for thirty days.

[0146] Accordingly, the multilayer films have an enhanced performance in respect of oxygen barrier properties over long periods of time. The time to reach equilibrium moisture content may be extended using controlled water vapour transmission rate other layers. The equilibrium % moisture content within the starch layer may be lower due to % relative humidity/% moisture content gradients within the other layer materials.

[0147] Such longevity in respect of gas barrier performance is clearly desirable in extending the shelf life of packaged perishable foodstuffs.

[0148] Advantageously, from a renewable perspective the multilayer film may contain a high proportion of biodegradable starch.

[0149] The thickness of the multilayer film and of each layer within the multilayer film may vary depending on the exact nature of the end use application.

[0150] The total thickness of the multilayer film may be between 5 and 1000 microns.

[0151] In some embodiments, the total thickness of the multilayer film may be between 10 and 100 microns, or between 20 and 80 microns.

[0152] In other embodiments, the total thickness of the multilayer film may be between 100 and 1000 microns or between 200 and 800 microns.

[0153] The total thickness of the at least one layer comprising a starch composition may be between 5 and 600 microns.

[0154] In some embodiments, the total thickness of the at least one layer comprising a starch composition may be between 5 and 50 microns, or between 10 and 40 microns.

[0155] In other embodiments, the total thickness of the at least one layer comprising a starch composition may be between 100 and 600 microns, or between 150 and 500 microns.

[0156] In some embodiments, the total thickness of the at least one other layer may be between 5 and 500 microns.

[0157] In some embodiments, the total thickness of the at least one other layer may be between 5 and 25 microns or between 10 and 20 microns.

[0158] In some embodiments, the total thickness of the at least one other layer may be between 30 and 400 microns, or between 30 and 300 microns.

[0159] The at least one layer comprising a starch composition may have a total thickness between 100 and 600 micron and the at least one other layer may have a total thickness between 10 and 400 micron.

[0160] The at least one layer comprising a starch composition may have a total thickness between 100 and 400 micron and the at least one other layer may have a total thickness between 40 and 250 micron.

[0161] The at least one layer comprising a starch composition may have a total thickness between 10 and 60 micron and the at least one other layer may have a total thickness between 5 and 40 micron.

[0162] The at least one layer comprising a starch composition may have a total thickness between 10 and 60 micron and the at least one other layer may have a total thickness between 5 and 500 micron.

[0163] The at least one layer comprising a starch composition may comprise water, preferably up to 20% by weight water, more preferably up to 12% by weight water. The water may serve as a plasticizer.

[0164] The moisture content of the at least one layer comprising a starch composition may be the equilibrium moisture content at the environmental % relative humidity. For example, the equilibrium moisture content may range from about 4% at low % RH to more than 15% at high % RH.

[0165] The layer comprising a starch composition and/or the other layer may comprise colourants.

Other Layer

[0166] The other layer(s) may be chosen to impart certain physical and aesthetic properties to finished multilayer film. These properties may include, for example, biodegradability in soil, water, marine or other environments, antifog, strength, heat sealability, colour, or clarity. The other layers may be those having a low water vapour transmission rate.

[0167] The at least one other layer may comprise a polyolefin, polyethylene terephthalate, polyethylene terephthalate glycol, polybutylene succinate, polyhydroxy butyrate, polylactic acid, nylon, polyvinylchloride, polyvinylidene dichloride, cellulose, a water resistant protein layer, a water resistant layer comprising silica, or mixtures thereof. Each of the other layers may comprise a mixture of components. One or more of the other layers may consist of multiple layers of different materials. Each of the other layers may comprise different materials. The layers may be solvent cast or sputter coated.

[0168] Suitable polyolefins for the preparation of the polyolefin film layer may be selected from the group consisting of ethylene homopolymers, propylene homopolymers, interpolymers of ethylene and propylene and interpolymers of ethylene or propylene with one or more C.sub.4-C.sub.10 α-olefins, cyclic olefin polymers and copolymers, biaxially orientated polypropylene, and mixtures thereof.

[0169] Suitable polyolefins may be selected from copolymers of ethylene or propylene and one or more α-olefins. Both high density polyethylenes and linear low density polyethylenes may be utilised.

[0170] Suitable linear low density polyethylenes (LLDPE) may include copolymers of ethylene and α-olefins (about 5 to about 15 wt. %). Alpha-olefins may include 1-butene, 1-hexene, 1-octene, and the like, and mixtures thereof. The density of LLDPE is within the range of about 0.865 to about 0.925 g/cm.sup.3

[0171] Suitable high density polyethylenes (HDPE) may include ethylene homopolymers and copolymers of ethylene and α-olefins (about 0.1 to about 10 wt. %). Suitable alpha-olefins may include 1-butene, 1-hexene, 1-octene, and the like, and mixtures thereof. The density of HDPE is preferably from about 0.940 to about 0.970 g/cm.sup.3.

[0172] Suitable cyclic olefin polymers and copolymers may include polymers of norbornene or tetracyclododecene and copolymers of norbornene or tetracyclododecene with one or more α-olefins. Examples include cyclic olefin polymers are Topas (Ticona) and Apel (Mitsui).

[0173] Blends of polyolefins and other polymers may be advantageously employed. Cast polypropylene (cPP) or biaxially oriented polypropylene (BOPP) may be chosen for improved strength and low WVTR. Polyethylene terephthalate (PET) may be chosen for strength and shrinkability.

[0174] Modified polyolefins, such as grafted polyolefins, may be utilized. A preferred grafted polyolefin is a maleic anhydride grafted polyolefin.

Polyolefins

[0175] Suitable LLDPE, HDPE and polypropylene may be produced by a Ziegler, single-site, or any other olefin polymerization catalyst. Ziegler catalysts and co-catalysts are well known in the art. Metallocene single-site catalysts are transition metal compounds that contain cyclopentadienyl (Cp) or Cp derivative ligands. For example, U.S. Pat. No. 4,542,199, teaches the preparation of metallocene catalysts. Non-metallocene single-site catalysts containing heteroatomic ligands, e.g., boraaryl, pyrrolyl, azaborolinyl or quinolinyl are also well known in the art.

[0176] The HDPE may also be multimodal. By “multimodal” it is meant that the polymer comprises at least two components, one of which has a relatively low molecular weight, the other a relatively high molecular weight. The multimodal polyethylene can be produced by polymerization using conditions that create a multimodal polymer product. This can be accomplished by using a catalyst system with two or more different catalytic sites or by using two or multi-stage polymerization processes with different process conditions in the different stages (e.g. different temperatures, pressures, polymerization media, hydrogen partial pressures, etc). Multimodal HDPE may be produced by a multistage ethylene polymerization, using a series of reactors, with comonomer addition in only one of the reactors.

[0177] The at least one other layer may comprise one or more materials derived from one or more renewable materials. The polyethylene or polypropylene may be derived from one or more renewable materials. The polyethylene may be prepared from ethanol derived from, for example, sugar cane, sugar beet or wheat grain. The polyethylene terephthalate may be derived from bio-polyols.

Adhesive

[0178] The at least one other layer may be fixed to the at least one layer comprising a starch composition through use of a suitable adhesive. This may assist in minimising slip and therefore maintaining excellent barrier performance. Numerous suitable adhesives would be apparent to those having skill in the present art. The adhesive may be selected to chemically bond to the at least one layer comprising a starch composition. Useful adhesives may comprise one or more polyurethanes or epoxies.

[0179] Advantageously, the use of an adhesive may overcome or minimise the need for modified or grafted other layers to be utilized as tie layers. Accordingly, for example, standard film polyethylene grades may be successfully employed as polyolefin other layers in the multi-layer film. This may be desirable from a cost consideration.

[0180] Other suitable adhesives may include EVA copolymers, acrylic copolymers and terpolymers, ionomers, metallocene derived polyethylene, maleic anhydride modified polyethylene, ethylene acrylic ester terpolymers and ethylene vinyl acetate terpolymers.

[0181] Those skilled in the art will be familiar with other adhesive lamination technology that would be suitable for adhering various types of plastics, including heat activated and UV activated systems. Exemplary adhesives may include, polyurethane, epoxy, nylon, acrylic and acrylate.

[0182] Polyurethane based adhesives may be particularly suitable for fixing the other layer to the layer comprising a starch composition. The polyurethane adhesive may be prepared in situ through reaction of one or more isocyanates with the starch layer. Through reaction of the surface hydroxyl functions of the starch with isocyanate, urethane functions are formed. Preferred isocyanates are diisocyanates. Those skilled in the art would be able to select suitable isocyanates from the wide range typically employed in the art of polyurethane synthesis.

[0183] Alternatively, the polyurethane adhesive may comprise one or more polyols. Such two component systems comprising diisocyanate and polyol are well known in the art.

[0184] The adhesives may or may not contain solvent. The solvent may be organic or water based.

[0185] Exemplary isocyanates include methylene diphenyl diisocyanate and toluene diisocyanate. Exemplary polyols include polyether polyols such as polyethylene glycol or polypropylene glycol and polyester polyols such as adipate based polyols.

Method of Preparation of the Multilayer Film

[0186] The multilayer film may be made by a variety of processes. The multilayer film may be made by co-extrusion, coating, extrusion coating, extrusion lamination and other laminating processes. The film may also be made by casting or blown film processes.

[0187] Coextrusion tends to use tie layers, and utilises modified other layers, such as modified (grafted) polyolefins. Coextrusion is generally able to achieve thinner overall gauges. Lamination is more suitable for thicker multilayer films utilising an adhesive. Extrusion coating may produce a coated product in an in-line process. Extrusion coating can apply much thinner polymer layers of polyolefin or polyester on to a substrate using a suitable adhesive resin.

[0188] In one embodiment a three layer film is provided comprising an inner layer comprising the starch composition and two outer polyolefin layers. In other embodiments adhesive layers may be employed between the layer comprising the starch composition and the polyolefin layers thus yielding a five layer film.

[0189] In another embodiment the starch layer may be extrusion coated onto a film substrate, for example a biaxially orientated polypropylene or paper substrate and then another layer, for example, a polyolefin or polyester layer, may be extrusion coated onto the starch layer.

Applications of Multilayer Film

[0190] It will be understood by those with skill in the art that a three or five-layer film is only one of many possible embodiments that employs starch and other layers. The number of layers and their relative thicknesses may be adjusted depending on the function or end-use of the film.

[0191] Additionally, further film layers comprising other materials commonly utilized in barrier film applications may be envisaged. Exemplary further film layers include metallized films, non-polymer films and the like.

[0192] The multilayer film may have many applications including grocery bags, stretch-wraps, food packaging films, package containers, package lids where low water vapour and oxygen transmission rates are required.

[0193] The following details exemplary embodiments according to the present disclosure.

Embodiment 1

[0194] A starch composition comprising:

[0195] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 4,000,000 Daltons;

[0196] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0197] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

Embodiment 2

[0198] A starch composition comprising:

[0199] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 4,000,000 Daltons;

[0200] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0201] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene; wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 3

[0202] A starch composition comprising:

[0203] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 4,000,000 Daltons;

[0204] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0205] c) from about 3% to about 30% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene; wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 4

[0206] A starch composition comprising:

[0207] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 4,000,000 Daltons;

[0208] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0209] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.
wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight, and the second starch has an amylose content of less than 20% by weight.

Embodiment 5

[0210] A starch composition comprising:

[0211] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 4,000,000 Daltons;

[0212] b) from about 0.1% to about 25% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0213] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.
wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight and the second starch has an amylose content of less than 20% by weight.

Embodiment 6

[0214] A starch composition comprising:

[0215] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0216] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0217] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

Embodiment 7

[0218] A starch composition comprising:

[0219] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0220] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0221] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene;

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 8

[0222] A starch composition comprising:

[0223] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0224] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0225] c) from about 3% to about 30% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene;

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 9

[0226] A starch composition comprising:

[0227] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0228] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0229] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.
wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight, and the second starch has an amylose content of less than 20% by weight.

Embodiment 10

[0230] A starch composition comprising:

[0231] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0232] b) from about 0.1% to about 25% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 1,000 and about 290,000 Daltons; and

[0233] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.
wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight and the second starch has an amylose content of less than 20% by weight.

Embodiment 11

[0234] A starch composition comprising:

[0235] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0236] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 100,000 and about 290,000 Daltons; and

[0237] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

Embodiment 12

[0238] A starch composition comprising:

[0239] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0240] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 100,000 and about 290,000 Daltons; and

[0241] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene;

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 13

[0242] A starch composition comprising:

[0243] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0244] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 100,000 and about 290,000 Daltons; and

[0245] c) from about 3% to about 30% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene;

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 14

[0246] A starch composition comprising:

[0247] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0248] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 100,000 and about 290,000 Daltons; and c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.
wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight, and the second starch has an amylose content of less than 20% by weight.

Embodiment 15

[0249] A starch composition comprising:

[0250] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0251] b) from about 0.1% to about 25% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 100,000 and about 290,000 Daltons; and

[0252] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.
wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight and the second starch has an amylose content of less than 20% by weight.

Embodiment 16

[0253] A starch composition comprising:

[0254] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0255] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 10,000 and about 100,000 Daltons; and

[0256] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

Embodiment 17

[0257] A starch composition comprising:

[0258] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0259] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 10,000 and about 100,000 Daltons; and

[0260] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene;

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 18

[0261] A starch composition comprising:

[0262] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0263] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 10,000 and about 100,000 Daltons; and

[0264] c) from about 3% to about 30% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene;

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.

Embodiment 19

[0265] A starch composition comprising:

[0266] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0267] b) from about 0.1% to about 40% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 10,000 and about 100,000 Daltons; and

[0268] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene.

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight.
wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight, and the second starch has an amylose content of less than 20% by weight.

Embodiment 20

[0269] A starch composition comprising:

[0270] a) from about 60% to about 99% by weight of a first starch, said first starch comprising one or more of unmodified starch and modified starch, said first starch having a first weight average molecular weight between about 300,000 and about 800,000 Daltons;

[0271] b) from about 0.1% to about 25% by weight of a second starch, said second starch comprising one or more of unmodified and modified starch, said second starch having a second weight average molecular weight between about 10,000 and about 100,000 Daltons; and

[0272] c) from about 1% to about 40% by weight of at least one water-soluble polymer comprising one or more of polyvinyl alcohol, polyvinyl acetate and polyoxyalkylene;

wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight;
or wherein the first starch has an amylose content of greater than about 10% by weight, or greater than about 20% by weight, or greater than about 30% by weight, or greater than about 40% by weight, or greater than about 50% by weight, or greater than about 60% by weight, or greater than about 70% by weight, or greater than about 80% by weight and the second starch has an amylose content of less than 20% by weight.

Embodiment 21

[0273] A starch composition according to any one of embodiments 1 to 20, wherein the first starch is present in an amount from about 70% to about 99% by weight, or from about 75% to about 99% by weight, or from about 80% to about 99% by weight, or from about 85% to about 99% by weight, or from about 90% to about 99% by weight, or from about 95% to about 99% by weight and the second starch is present in an amount from about 0.1% to about 35% by weight, or from about 0.2% to about 30% by weight, or from about 0.5% to about 25% by weight, or from about 0.5% to about 20% by weight, or from about 0.5% to about 15% by weight, or from about 0.5% to about 10% by weight, or from about 0.5% to about 5% by weight, or from about 0.5% to about 4% by weight, or from about 0.5% to about 3% by weight, or from about 0.5% to about 2% by weight.

Embodiment 22

[0274] A film, said film having a thickness between 5 and 600 microns, said film comprising a starch composition as disclosed in any one of Embodiments 1 to 21;

wherein the film has an OPC of less than 0.07 cm.sup.3.mm./m.sup.2.day.atm measured at 50% RH according to ASTM F1297.

Embodiment 23

[0275] A film, said film having a thickness between 5 and 600 microns, said film comprising a starch composition as disclosed in any one of Embodiments 1 to 20; wherein the film has an OPC of less than 0.06 cm.sup.3.mm./m.sup.2.day.atm measured at 50% RH according to ASTM F1297.

Embodiment 24

[0276] A film, said film having a thickness between 5 and 600 microns, said film comprising a starch composition as disclosed in any one of Embodiments 1 to 20; wherein the film has an OPC of less than 0.05 cm.sup.3.mm./m.sup.2.day.atm measured at 50% RH according to ASTM F1297.

[0277] In any one of embodiments 21 to 24 the film may have an OPC of less than 0.02 cm.sup.3.mm./m.sup.2.day.atm, or less than 0.01 cm.sup.3.mm./m.sup.2.day.atm, or less than 0.005 cm.sup.3.mm./m.sup.2.day.atm according to ASTM F1927 measured at 50% relative humidity.

[0278] There is also provided a multilayer film comprising one or more layers comprising a film according to any one of embodiments 21 to 24 and at least one other layer selected from the group consisting of polyolefin, polyethylene terephthalate, polyethylene terephthalate glycol, polybutylene succinate, polyhydroxy butyrate, polylactic acid, nylon, polyvinylchloride, polyvinylidene dichloride, cellulose, a water-resistant protein layer, a water-resistant layer comprising silica and combinations thereof.

EXAMPLES

Raw Materials

[0279] The following raw materials were used in the Examples.

[0280] Modified starch ECOFILM™; a propylene oxide modified starch, 70% amylose content; Ingredion.

[0281] Modified starch National 7; a propylene oxide modified starch, <20% amylose content; Ingredion.

[0282] Modified starch Bondstar T800; a propylene oxide modified starch, <20% amylose content; Ingredion.

[0283] Unmodified starch Pencote D ULV; <1% amylose content; Ingredion.

[0284] Modified starch National 912; an OSA (octenyl succinic anhydride) modified starch, <20% amylose content; Ingredion.

[0285] Polyvinylalcohol; (Elvanol™ 71-30; Kuraray)

[0286] Cloisite 20A hydrophobically modified layered silicate clay (BYK Chemie GmbH).

[0287] Table 1 contains data on the five starches used in the Examples.

TABLE-US-00001 TABLE 1 Amy- lose Modifi- Method to Starch Mw Starch (wt %) cation.sup.1 reduce MW source (GPC).sup.2 Ecofilm 70 HP — Corn 450,000 National 7 <20 HP — Tapioca 1,100,000 BONDSTAR <20 HP Hypo- Tapioca 190,000 T800 chlorous acid Pencote <1 None Enzyme Waxy corn 31,000 D ULV National <20 OSA Acid Corn 230,000 912 .sup.1HP = hydroxypropylated .sup.2determined using gel permeation chromatography.

Starch Compositions

[0288] Starch compositions 1 to 5 were prepared by extrusion processing a mixture of starch (A), starch (B) and PVOH (Table 2). Comparative example 1 also contained 1.8% by weight clay based on the total weight of the starch composition. The weight ratios of the starches and PVOH are based on the total weight of these three components. The % LMW starch is based on the weight of LMW starch relative to the total weight of starch in the composition. Starch compositions 6 to 9 were similarly prepared by extrusion processing but only contained either Ecofilm or National 7 as the single starch component (Table 3).

TABLE-US-00002 TABLE 2 Weight % Starch Starch PVOH ratio LMW Composition (A) (B) (C) (A/B/C) starch Clay % 1 Ecofilm National7 Elvanol 68.3/22.7/9.0 N/A 1.8 (comparative) 71-30 2 Ecofilm Bondstar T800 81.9/9.1/9.0 10 N/A 3 Ecofilm Bondstar T800 68.3/22.7/9.0 25 4 Ecofilm Pencote D ULV 90.1/0.9/9.0 1 5 Ecofilm Pencote D ULV 86.4/4.6/9.0 5

TABLE-US-00003 TABLE 3 Composition Starch PVOH Clay (comparative) ca. 89 wt. % ca. 9 wt. % ca. 2 wt. % 6 Ecofilm Elvanol 71-30 Cloisite 20A 7 Ecofilm Elvanol 71-30 N/A 8 National7 Elvanol 71-30 Cloisite 20A 9 National 7 Elvanol 71-30 N/A

[0289] The extruded starch compositions were processed into films having a thickness indicated in Table 4. The Table also collects oxygen barrier and mechanical property data for the films. Oxygen transmission rate of the films of the starch compositions was measured according to ASTM F1927 at 50% relative humidity.

TABLE-US-00004 TABLE 4 Oxygen Barrier OTR OPC Tensile (cc/m.sup.2 .Math. (cc .Math. mm/ Elongation day .Math. atm) m.sup.2 .Math. day .Math. atm) Elastic at break Film impact 23° C. Thickness 23° C. modulus (%) (mN/μm) Composition 50% RH (μm) 50% RH (MPa) (23° C.) Ave. Dev. 1 0.72 100 0.072 2411 18 5.8 0.9 (comparative) 2 0.42 100 0.042 2497 11 4.0 3.4 3 0.38 80 0.030 2542 4 0.7 0.2 4 0.44 90 0.040 2570 22 10.5 4.1 5 0.32 100 0.032 2528 18 1.7 0.6 6 0.30 264 0.079 — — — — (comparative 7 0.20 268 0.054 — — — — (comparative) 8 0.24 257 0.062 — — — — (comparative) 9 0.27 252 0.068 — — — — (comparative)

[0290] The results demonstrate that inventive compositions 2 through 4 which comprise added low molecular weight starch components afforded films having superior oxygen barrier properties. Furthermore, as the molecular weight of the low molecular weight starch component decreased (compositions 4 and 5) less low molecular weight component was required in order to attain improved gas barrier performance. Comparative examples 1 and 6 to 9, which either comprise only a single high molecular weight starch component or a mixture of high molecular weight starch components, all show poorer oxygen barrier performance.

[0291] Film impact was measured according to ASTM D3420 at 23° C. and 50% relative humidity on an unformed sheet of the starch composition.

Thermoformability of Starch Films

[0292] Further starch compositions 10 to 12 and comparative example 13 were prepared (for composition see Table 5), extruded and processed into films, by analogous methods to those described above for starch compositions 1 to 5 and comparative examples 6 to 9.

TABLE-US-00005 TABLE 5 Weight Film Starch Starch ratio % LMW Thickness Composition (A) (B) (A/B) starch (μm) 10 Ecofilm Pencote 9:1 10 118 D ULV 11 Ecofilm National 9:1 10 139 912 12 Ecofilm Bondstar 9:1 10 102 T800 13 Ecofilm N/A 414 (Comparative)

[0293] Thermoformability of starch films is associated with tensile elongation at break at elevated temperature. The above films were evaluated for their tensile elongation at break at 100° C. by using 15 mm wide strips of the starch films encased in a PET laminate. Tensile elongation at break is measured in % (% of elongation vs initial size when yield point is reached). Tensile speed was 500 mm/min. The % elongation at break results at 100° C. are shown in Table 6.

TABLE-US-00006 TABLE 6 Elongation at break Composition (%) 10 85 11 98 12 75 13 62 (Comparative)

[0294] The results show that starch films containing a high molecular weight and a low molecular weight starch have improved elongation at break at 100° C. compared with a film containing only a high molecular weight starch.

Drawability of Starch Films

[0295] The drawability of extruded starch film sheets was evaluated by forming into cups of different geometry on a thermoforming machine. The composition of the starch films is shown in Table 7.

TABLE-US-00007 TABLE 7 Weight % Extrusion Film Starch Starch PVOH ratio LMW Speed Thickness Composition (A) (B) (C) (A/B/C) starch (rpm) (μm) 14 Ecofilm Pencote PVOH 87.7:1.8:10.5 2 620 120 D ULV 15 Ecofilm Pencote PVOH 87.7:1.8:10.5 2 920 120 D ULV 16 Ecofilm N/A Elvanol 90.5:9:0.5 N/A 620 120 (Comparative) 71-30 17 Ecofilm N/A Elvanol 90.5:9:0.5 N/A 920 120 (Comparative) 71-30

[0296] A 12 cavity draw ratio tool was used, having 12 individual cups of the same 50 mm diameter, but which are progressively deeper (from 25 mm to 50 mm) and there are two sets of cups with different radius in the bottom corner (4 mm radius and 8 mm radius). A large radius is less severe when drawn and so the 8 mm radius normally draws more easily than the 4 mm radius cavity. Use of the draw ratio tool gives an area draw ratio from 3.0 to 5.0, depending on the cavity.

[0297] For each film composition tested, approximately 5 meters length of sheet of minimum width 300 mm was used. Ten sample sheets were tested for each film composition. The sample sheets were heated, and formed using the cavity draw ratio tool.

[0298] For each sheet sample, the number of cavities successfully formed was recorded. This was repeated for the ten samples

[0299] The cavity number from the draw ratio tool is correlated with grading percentage as follows:

TABLE-US-00008 TABLE 8 Corner Cavity Depth Radius Grading Area Draw No. (mm) (mm) % Ratio 1 25 8 50%-8 3.0 2 25 4 50%-4 3.0 3 30 8 60%-8 3.4 4 30 4 60%-4 3.4 5 35 8 70%-8 3.8 6 35 4 70%-4 3.8 7 40 8 80%-8 4.2 8 40 4 80%-4 4.2 9 45 8 90%-8 4.6 10 45 4 90%-4 4.6 11 50 8 100%-8  5.0 12 50 4 100%-4  5.0

[0300] The results for compositions 14-15 and comparators 16 and 17 are shown in Table 9.

TABLE-US-00009 TABLE 9 Cavity No./Grading %/No of Composition cavities successfully formed 14 4/60%-4/10 cavities 3/60%-8/10 cavities 15 4/60%-4/10 cavities 3/60%-8/10 cavities 16 4/60%-4/8 cavities  (Comparative) 3/60%-8/10 cavities 17 4/60%-4/2 cavities  (Comparative) 3/60%-8/10 cavities

[0301] The results show that starch films containing a high molecular weight and a low molecular weight starch have improved draw compared with a film containing only a high molecular weight starch.

[0302] The contents of all references, including published patents and patent applications cited throughout the application are hereby incorporated by reference.

[0303] It is understood that the detailed examples and embodiments described herein are given by way of example for illustrative purposes only, and are in no way considered to be limiting to the disclosure. Various modifications or changes in light thereof will be suggested to persons skilled in the art and are included within the spirit and purview of this application and are considered within the scope of the appended claims. For example, the relative quantities of the ingredients may be varied to optimize the desired effects, additional ingredients may be added, and/or similar ingredients may be substituted for one or more of the ingredients described. Additional advantageous features and functionalities associated with the systems, methods, and processes of the present disclosure will be apparent from the appended claims. Moreover, those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the disclosure described herein. Such equivalents are intended to be encompassed by the following claims.