BIODEGRADABLE POLYMERIC MIXTURE AND METHOD FOR ITS PREPARATION

Abstract

A biodegradable polymer blend contains at least one component (A), at least one component (B) and at least one component (D), whereincomponent (A) includes polymers based on lactic acidcomponent (B) includes thermoplastic starch (TPS) representing a mixture of starch, at least one plasticizer from the group of substances (C), and at least one modifier from the group of substances (E); group of substances (C) includes plasticizers for starchgroup of substances (E) includes modifierscomponent (D) includes homopolymers or copolymers of polyhydroxyalkanoates (PHAs), and/or mixtures thereof, and the biodegradable polymer blend can optionally contain a component (F), whereincomponent (F) includes plasticizers for PLAs and/or for PHAs, and the biodegradable polymer blend is prepared in a such way that a composition containing the components (A), (B) and (D) is prepared by blending the components (A) and (B), wherein the component (B) is present in the blend at least in one phase of the blending process where at least one component (B) and at least one component (A) are blended concurrently, and this phase of the blending process precedes, by at least one phase, that phase of the blending process where the component (D) is added to the blend, and the optional components (F) and (G) can be added to the blend in any one or multiple phases of the blending process, and in one or several doses.

Claims

1. A biodegradable polymer blend comprising at least one component (A), at least one component (B), and at least one component (D), wherein component (A) includes polymers based on lactic acid, wherein the polymers based on lactic acid comprise homopolymers of PLLA, PDLA, as well as their copolymers, or mixtures of their homopolymers, mixtures of their homopolymers and copolymers, or mixtures of their copolymers; component (B) includes thermoplastic starch (TPS), representing a mixture of starch, at least one plasticizer from the group of substances (C), and at least one modifier from the group of substances (E); group of substances (C) includes plasticizers for starch; group of substances (E) includes modifiers, wherein the modifiers comprise saturated or unsaturated carboxylic acids, dicarboxylic acids, tricarboxylic acids or polycarboxylic acids, saturated or unsaturated anhydrides, and mixed anhydrides of carboxylic acids, substances containing isocyanate groups substances containing expoxide groups, acyl halides, acyl imidazoles, acylphosphates, thioesters of acids, or a combination thereof; component (D) includes homopolymers or copolymers of polyhydroxyalkanoates (PHAs), and/or their mixtures; and the biodegradable blend can optionally contain component (F), wherein component (F) includes plasticizers for PLA and/or for PHA.

2. The biodegradable polymer blend of claim 1, wherein the biodegradable blend consists of at least one component (A), at least one component (B) and at least one component (D).

3. A biodegradable polymer blend of claim 2, wherein the blend shows tensile strength .sub.M equal or higher than 15 MPa, wherein relative elongation at break .sub.b is higher or equal than 2.0%, and the parameters relative elongation at break .sub.b and tensile strength .sub.M are evaluated by analysis of tensile curves.

4. The biodegradable polymer blend of claim 1, wherein the biodegradable blend consists of component (F), and shows relative elongation at break .sub.b is higher or equal than 100%, wherein tensile strength .sub.M is higher or equal than 3.0 MPa, and the parameters relative elongation at break .sub.b and tensile strength .sub.M are evaluated by analysis of tensile curves.

5. The biodegradable polymer blend of claim 1, wherein the ratio (A):(D) is from 95:5 to 5:95.

6. The biodegradable polymer blend of claim 1, wherein the quantity of starch used in component (B) shall be such that the ratio [(A)+(D)]:(starch) is from the interval 97:3-40:60.

7. The biodegradable polymer blend of claim 1, wherein the quantity of substance from the group (C) in component (B) shall be such that the ratio of a substance from the group (C):(starch) is at least 5:95.

8. The biodegradable polymer blend of claim 1, wherein in the component (B), the ratio of a substance from the group (E):[(starch+substance from the group (C)] is at least 0.05:100.

9. The biodegradable polymer blend of claim 1, wherein the ratio (F):[(A)+(D)] is at least 5:95.

10. The biodegradable polymer blend of claim 1, wherein the blend contains component (G) to modify processing and/or utility properties of the blend, wherein the component (G) includes mainly inorganic or organic fillers, compatibilizers and interphase agents, pigments and dyes, nucleating agents, processing aids, anti-block and slip additives, cross-linking additives, foaming agents, antistatic additives, flame retardants, antidegradants, and other additives and modifiers, including polymers and oligomers.

11. A method for preparation of the biodegradable polymer blend of claim 1, wherein the composition containing components (A), (B) and (D) is prepared in a such way that components (A) and (B) are blended, wherein component (B) is present in the blend at least in one phase of the mixing process where simultaneously at least one component (B) and at least one component (A) are blended, and this phase of the blending process precedes by at least one phase that blending phase of the blending process where component (D) is added to the blending process, and optional components (F) and (G) can be added to the blend in any one or multiple phases of the blending process, either in one or in multiple doses.

12. The method for preparation of the biodegradable polymer blend of claim 11, wherein all phases of the blending process are carried out in one blending step.

13. The method for preparation of the biodegradable polymer blend of claim 11, wherein at the beginning of blending process, a dryblend is prepared by mixing at laboratory temperature, wherein the dryblend consists of starch and at least one modifier (E), and the dryblend optionally can contain one or more components (C), and together with the dryblend, also a polymer from the group (A) can be added to the blend, wherein at least one substance from the group (C) is added to the blend at latest in that phase of the blending process which precedes by at least one phase the phase of the blending process in which component (D) is added to the blend, and at least one substance from the group (A) is added to the blend in that phase of the blending process which precedes at least one phase that phase of the blending process in which component (D) is added to the blend, wherein the order of dosing substances from the group (A) and (C) is discretionary, and one or multiple components (D) are added to the blend in a such phase of the blending process, which follows by at least one phase of the blending process the phase in which are simultaneously blended: starch, at least one component (A), at least one substance from the group (C), and at least one substance from group (E); wherein components (F) and (G) can be added to the blend in any phase of the blending process; and before the output of a hot-melt from the last blending step, an excessive humidity of the blend is removed by atmospheric or vacuum degassing, and the produced blend in hot-melt form is: (i) cooled by liquid or gas, preferably by water or air, and granulated (ii) or lead to a die for producing final products or intermediates.

14. The method for preparation of the biodegradable polymer blend of claim 13, further comprising a multiple step method of production, and hot-melt of the blend containing at least one component (A) and at least one component (B) without presence of component (D) is, without removal of excessive water on output from the given blend step, cooled by liquid or gas, and granulated, and the produced pellets are fed to the next blending step, wherein also a polymer from the group (D) is added to the blend together with the pellets, or the polymer from the group (D) is added to the blend at latest in the last but one blending phase of the given blending step, and the excessive humidity is removed by atmospheric of vacuum degassing before the completion of the last blending step, prior to output from the blending device, and the produced blend in a form of hot-melt is then: (i) cooled by liquid or gas and granulated (ii) or lead to a die for producing final products or intermediates.

15. The method for preparation of the biodegradable polymer blend of claim 14, wherein the production is performed in a blending device in two blending steps.

16. The biodegradable polymer blend of claim 2, wherein the ratio (A):(D) is from 95:5 to 5:95.

17. The biodegradable polymer blend of claim 3, wherein the ratio (A):(D) is from 95:5 to 5:95.

18. The biodegradable polymer blend of claim 4, wherein the ratio (A):(D) is from 95:5 to 5:95.

19. The biodegradable polymer blend of claim 4, wherein the ratio (F):[(A)+(D)] is at least 5:95.

20. The method for preparation of the biodegradable polymer blend of claim 12, wherein at the beginning of blending process, a dryblend is prepared by mixing at laboratory temperature, wherein the dryblend consists of starch and at least one modifier (E), and the dryblend optionally can contain one or more components (C), and together with the dryblend, also a polymer from the group (A) can be added to the blend, wherein at least one substance from the group (C) is added to the blend at latest in that phase of the blending process which precedes by at least one phase the phase of the blending process in which component (D) is added to the blend, and at least one substance from the group (A) is added to the blend in that phase of the blending process which precedes at least one phase that phase of the blending process in which component (D) is added to the blend, wherein the order of dosing substances from the group (A) and (C) is discretionary, and one or multiple components (D) are added to the blend in a such phase of the blending process, which follows by at least one phase of the blending process the phase in which are simultaneously blended: starch, at least one component (A), at least one substance from the group (C), and at least one substance from group (E); wherein components (F) and (G) can be added to the blend in any phase of the blending process; and before the output of a hot-melt an excessive humidity of the blend is removed by atmospheric or vacuum degassing, and the produced blend in hot-melt form is: (i) cooled by liquid or gas, preferably by water or air, and granulated, or (ii) lead to a die for producing final products or intermediates.

21. The method for preparation of the biodegradable polymer blend of claim 11, comprising a multiple step method of production, and hot-melt of the blend containing at least one component (A) and at least one component (B) without presence of component (D) is, without removal of excessive water on output from the given blend step, cooled by liquid or gas, and granulated, and the produced pellets are fed to the next blending step, wherein also a polymer from the group (D) is added to the blend together with the pellets, or the polymer from the group (D) is added to the blend at latest in the last but one blending phase of the given blending step, and the excessive humidity is removed by atmospheric of vacuum degassing before the completion of the last blending step, prior to output from the blending device, and the produced blend in a form of hot-melt is then: (i) cooled by liquid or gas and granulated (ii) or lead to a die for producing final products or intermediates.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0048] FIG. 1. Example of the dependence of viscosity on shear rate of the plasticiser acetylbutylcitrate, measured according to STN ISO 3219

[0049] FIG. 2 Scheme of the process for producing a polymer blend according to procedure PA in the two extrusion steps, PA1 and PA2

[0050] FIG. 3 Scheme of the process for producing a polymer blend according to procedure PB in the two extrusion steps, PB1 and PB2

[0051] FIG. 4 Scheme of the process for producing a polymer blend according to procedure PC in the two extrusion steps, PC1 and PC2

[0052] FIG. 5 Scheme of the process for producing a polymer blend according to procedure PD in a single extrusion step

[0053] FIG. 6 Scheme of the process for producing a polymer blend according to procedure PE in a single extrusion step

[0054] FIG. 7 Scheme of the process for producing a polymer blend according to procedure PF in a single extrusion step

[0055] FIG. 8 Scheme of the process for producing a polymer blend according to procedure G in the two possible alternatives, PG1 and PG2

DETAILED DESCRIPTION OF THE INVENTION

[0056] The below mentioned procedures were used to determine properties of blend of the invention:

Measuring Mechanical Properties of Blends

[0057] Mechanical properties of blends of the invention were measured according to the standard STN ISO 527 on the tensile testing device Zwick Roell equipped by a mechanical extensometer, wherein measurement was carried out at the temperature 25 C., relative air humidity (RH) 50%, and rate of cross head speed 50 mm/min. The clamping length of the testing piece was 50 mm, and the distance of extensometer grips was 30 mm. According to STN ISO 527, the parameters: relative elongation at break .sub.b and tensile strength .sub.M were evaluated by analysis of tensile curves.
Testing Pieces for Mechanical Properties Measurements and their Preparation [0058] To prepare testing pieces for mechanical properties measurements, films of the thickness 0.040 mm were produced of used blends by chill roll technology, specifically via extrusion of hot-melt of blend on water-cooled cylinders of the laboratory chill roll line, including the following individual devices: [0059] Take off unit (fy Gttfert) equipped by two consecutive water-cooled cylinders, and further by a take-off and winding units. The temperature of cooled cylinders: 20 C. [0060] The extruder head with a flat die of the width 70 mm, and 0.4 mm slit thickness, connected either directly to the extruder of the last extrusion step, as a replacement of granulation device, or connected to the laboratory single-screw extruder (Brabender) with 19 mm screw diameter, ratio L/D=25 and the screw compression ratio 1:2. Screw geometry: A smooth screw without mixing elements with a steady increasing diameter of the screw core. In case of the used single-screw extruder produced by the company Brabender, the processing parameters were as follow: [0061] The hot melt temperature: 190 C. [0062] The screw revolutions: 30 rev/min [0063] Blown films produced in this way were immediately after the production cut to tapes of 15 mm width and 100 mm length, forthwith placed to a conditioning cabinet to allow conditioning the samples for 24 hours at 25 C. and 50% RH. Mechanical properties were measured immediately after the 24 hour conditioning period.

Measurement of Plasticizer Viscosity

[0064] The viscosity of plasticizers was measured using the coaxial-cylinder rotational viscometerHaake rheoviscometer. Measurement was carried out at 25 C., in accordance with STN ISO 3219, wherein the viscosity value was the average value of all measurements within the shear rate range of 152 s.sup.1 to 1170 s.sup.1, as all measured fluids showed the Newtonian fluid character. An example of the dependence of viscosity on shear rate of the plasticiser acetylbutylcitrate is shown on FIG. 1.

[0065] Examples of methods for preparing biodegradable polymer blends can include the following: Two-step or single-step alignment alternatives for preparation of blends, using twin-screw extruders, wherein the mentioned following examples are non-limiting, i.e. other alternatives of the blending process alignment are possible, too. Extruders on Figures are schematically drawn, wherein division of any extruder to zones is only illustrative, and does not represent the specific order of zones or the specific order of the blending process phases.

1. Two-Extrusion Preparation

Procedure PA

[0066] According to procedure PA, it is prepared a dryblend (DB_A) consisting of at least starch, at least one plasticizer from the group of substances (C), and at least one modifier from the group of substances (E), wherein, in addition to these components, the dryblend can contains other additives from the group of substances (G), or not. During the first extrusion step PA1, the dryblend is fed to a hopper of co-rotating twin-screw extruder together with at least one component (A). Then, using a pump, component (F) is dosed to a melted mixture, if it is necessary for final properties of the blend. After output from the extruder, the blend is cooled, and granulated without exhausting excessive water. The prepared pellets are then fed again to a hopper feeder of the twin-screw extruder during the second extrusion step PA2 together with at least one component (D). In case of necessity, other component F can be again fed to hot-melt using a pump. At the end of extruder, excessive water is removed via a vacuum degassing zone, the mixture is cooled using air- or fluid-cooling, and granulated. Humidity of the final pellets can be (if it is necessary) adjusted by drying, and then further processed. A granulation unit can by preferably replaced by a production unit producing some final products (chill roll films, blown films, etc.), that is connected to the extruder in step PA2. Other substances from the group (G) can be added (if it is necessary) to mixture either to an extruder hopper during the first extrusion step PA1, or to hot-melt along the extruder using a side feeder. By the similar way, other additives from the group (G) can be dosed also in the second extrusion step PA2. The procedure is schematically drawn on FIG. 2.

Procedure PB

[0067] According to procedure PB, it is prepared a dryblend (DB_B), consisting of at least starch, at least one substance from the group (C), and at least one modifier from the group of substances (E), wherein, in addition to these components, the dryblend can contains other additives from the group of substances (G), or not. The dryblend is fed to a hopper of the co-rotating twin-screw extruder during the first extrusion step PB1. Then, at least one component (A) is dosed to a melted mixture using a pump, and after that, component (F) can be dosed to the hot-melt if it is necessary for final properties of blend. After output from the extruder, the produced blend is cooled and granulated without exhausting excessive water. Thereafter, the formed pellets are fed again to a hopper of the twin-screw extruder during the second extrusion step PB2, together with at least one component (D). If necessary, it is possible to dose again other component (F) to hot-melt in extruder, using a pump. At the end of extruder, excessive water is removed via the vacuum or atmospheric degassing zone, the blend is cooled by air or fluid, and granulated. Granulation can be omitted, and during step PB2, some device for production of final products can be preferably attached to the extruder as a replacement of a granulation unit. Produced final products can include chill roll films, blown films etc.) Prior to further processing, humidity of the final pellets can be (if necessary) adjusted by drying. In case of necessity, other substances from the group (G) can be dosed to hot-melt either during the first extrusion step PB1to an extruder hopper, or to hot-melt along the extruder, using a side feeder. By the similar way, other additives from the group (G) can be dosed also in the second extrusion step PB2. The procedure is schematically drawn on FIG. 3.

Procedure PC

[0068] According to procedure PC, it is prepared a dryblend (DB_C), consisting of at least starch, and at least one modifier from the group or substances (E), wherein in addition to these components, the dryblend can contains other additives from the group of substances (G), or not. The dryblend is fed to a hopper of the co-rotating twin-screw extruder during the first extrusion step PC1. Then, at least one plasticizer from the group (C) is dosed to hot-melt using a pump, and after that at least one component (A), and if is necessary for final properties of blend, also component (F) is then dosed to a melted mixture, using a pump.

[0069] After output from extruder, the produced blend is cooled and granulated without exhausting excessive water. Thereafter, the formed pellets are dosed again to a hopper of the twin-screw extruder during the second extrusion step PC2, together with at least one component (D). If necessary, it is possible to dose again other component (F) to hot-melt in extruder, using a pump. At the end of extruder, excessive water is removed via the vacuum or atmospheric degassing zone, the blend is cooled by air or fluid, and granulated. Prior to further processing, humidity of the final pellets can be (if necessary) adjusted. During step PC2, some unit for production of final products can be preferably attached to the extruder as a replacement of a granulation unit. Produced final products can include chill roll films, blown films etc.).

[0070] In case of necessity, other substances from the group (G) can be dosed to hot-melt either during the first extrusion step PC1to an extruder hopper, or to hot-melt along the extruder, using a side feeder. By the similar way, other additives from the group (G) can be dosed during the second extrusion step PC2, too. The procedure is schematically drawn on FIG. 4.

[0071] Alternatively, for all the procedures, PA to PC, PHA (component (D)) can be dosed during the second extrusion step PA2 to PC2 not only to a hopper but also and/or to hot-melt, using a side feeder, prior to or after dosing the component (F)FIG. 2-4.

2. One-Extrusion Preparation

Procedure PD

[0072] According to procedure PD, it is prepared a dryblend (DB_D) consisting of at least starch, at least one plasticizer from the group of substances (C), and at least one modifier from the group of substances (E), wherein, in addition to these components, the dryblend can contains other additives from the group (G), or not. Dryblend is fed to a hopper of the co-rotating twin-screw extruder together with at least one component (A) Then, if it is necessary for final properties of blend, component (F) is dosed to hot-melt in the extruder, using a pump, and at least one component (D) is dosed through a side feeder in the second half of the extruder, and then, in case of necessity, additives from the group of substances (G) are dosed. At the end of extruder, excessive water is removed via a vacuum or atmospheric degassing zone, the blend is cooled using air- or fluid-cooling, and granulated. Humidity of the final pellets can be (if it is necessary) adjusted by drying prior to further processing the pellets. Some device for production of final products can be preferably attached to the extruder as replacement of a granulation unit. Final products can include chill roll films, blown films, and etc.). The procedure is schematically drawn on FIG. 5.

Procedure PE

[0073] According to procedure PE, it is prepared a dryblend (DB_E) consisting of at least starch, at least one plasticizer from the group of substances (C), and at least one modifier from the group of substances (E), wherein, in addition to these components, the dryblend can contains other additives from the group of substances (G), or not. The dryblend is dosed to a hopper of the co-rotating twin-screw extruder, and after that, at least one component (A) is dosed. In other part of extruder, component (F) is dosed using a pump, if it is necessary for final properties of blend. In the second half of extruder, at least one component (D) is dosed through a side feeder, and then, in case of necessity, additives from the group of substances (G) are dosed. At the end of extruder, excessive water is removed via a vacuum degassing zone, the mixture is cooled using air- or fluid-cooling, and granulated. Humidity of the final pellets can be if necessary adjusted by drying prior to further processing of pellets. Some device for production of final products can be preferably attached to the extruder as a replacement of a granulation unit. Produced final products can include chill roll films, blown films etc. The procedure is schematically drawn on FIG. 6.

Procedure PF

[0074] According to procedure PF, it is prepared a dryblend (DB_F), consisting of at least starch, and at least one modifier from the group of substances (E), wherein, in addition to these components, the dryblend can contains other additives from the group of substances (G), or not. The dryblend is fed to a hopper of the co-rotating twin-screw extruder together with at least one component (A), and after that, at least one plasticizer from the group of substances (C) is dosed to the extruder using a pump. In other part of extruder, component (F) is dosed using a pump, if it is necessary for final properties of the blend. In the second half of extruder, at least one component (D) is dosed through a side feeder, and then, in case of necessity, additives from the group of substances (G) are dosed. At the end of extruder, excessive water is removed via a vacuum degassing zone, the blend is cooled using air- or fluid-cooling, and granulated. Prior to further processing, humidity of the final pellets can be (if necessary) adjusted by drying. As a replacement of granulation, some device for production of final products can be preferably attached to the extruder. Produced final products can include chill roll films, blown films and etc. The procedure is schematically drawn on FIG. 7.

[0075] Procedure PG According to procedure PG, it is prepared a dryblend (DB_G) consisting of at least starch, at least one modifier from the group of substances (E), wherein, in addition to these components, additives from the group of substances (G) can be contained or not. The dryblend is fed to a hopper of co-rotating twin-screw extruder, and after that, at least one plasticizer from the group of substances (C) is dosed to hot-melt in extruder, and then at least one component (A) procedure PG1, or at first at least one component (A), and after that, at least one plasticizer from the group of substances (C)procedure PG2. In other part of extruder, plasticizer from the group of substances (F) is dosed using a pump, if is necessary for final properties of blend. In the second half of extruder, at least one component (D) is dosed through a side feeder, and then, in case of necessity, additives from the group of substances (G) are dosed. At the end of extruder, excessive water is removed via a vacuum degassing zone, the mixture is cooled using air- or fluid-cooling, and granulated. Humidity of the final pellets can be if necessary adjusted by drying prior to further processing of pellets. A granulation part can be omitted, and some production device for production of final products can preferably replace a granulation unit. Final products can include chill roll films, blown films etc. The procedure is schematically drawn on FIG. 8.

[0076] There were prepared reference blends that are not within range of the invention, but they serve only for comparison of mechanical properties with the blends prepared in accordance with the invention. The reference blends of composition mentioned in Table 1 & 2 were prepared under the following conditions:

[0077] The twin-screw blending device with co-rotating screws was used as a device, and is characterized by the following parameters:

[0078] Screw diameter 26 mm, L/D=40

[0079] Screw revolutions: 200 rev./min

[0080] Hot-melt temperature 180 C.

[0081] Vacuum degassing on the last zone of the screw

[0082] An extruded blend was cooled by air and then granulated. Prepared blends were processed by chill roll technology, and films of 0.040 mm thickness were prepared by method according to description of the invention.

[0083] If TPS was prepared separately, its preparation was as follows:

[0084] Dryblend was prepared by mixing in a laboratory high speed mixer produced by company Labtech, and consisting of starch and plasticizer from the group of substances (C). This dryblend was fed to hopper feeder of twin-screw extruder, where it was processed under the following conditions:

[0085] Screw diameter 26 mm, L/D=40

[0086] Screw revolutions: 200 rev./min

[0087] Hot-melt temperature 150 C.

[0088] Vacuum degassing on the last zone of the screw

[0089] The produced TPS was extruded as a strand, cooled by air, and then granulated.

TABLE-US-00001 TABLE 1 Composition of reference blends without plasticizer from the group (F) and without modifier from the group (E) No. of Starch:[(A) + F:[(A) + Technological blend (A):(D) (D)] (C):Starch (D)] Procedure 1 80:20 30:70 30:70 0 TP1 2 40:60 30:70 30:70 0 TP1 3 5:95 30:70 30:70 0 TP1 4 95:5 30:70 30:70 0 TP2 5 80:20 30:70 30:70 0 TP2 6 40:60 30:70 30:70 0 TP2 7 5:95 30:70 30:70 0 TP2 8 95:5 30:70 30:70 0 TP3 9 80:20 30:70 30:70 0 TP3 10 40:60 30:70 30:70 0 TP3 11 5:95 30:70 30:70 0 TP3

TABLE-US-00002 TABLE 2 Composition of reference blends with a plasticizer from the group (F) and without modifier from the group (E) No. of Starch:[(A) + F:[(A) + Technological blend (A):(D) (D)] (C):Starch (D)] Procedure 12 80:20 30:70 30:70 0 TP1 13 40:60 30:70 30:70 0 TP1 14 5:95 30:70 30:70 0 TP1 15 95:5 30:70 30:70 0 TP2 16 40:60 30:70 30:70 0 TP2 17 5:95 30:70 30:70 0 TP2 18 95:5 30:70 30:70 0 TP3 19 40:60 30:70 30:70 0 TP3 20 5:95 30:70 30:70 0 TP3 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch-Corn Starch (C)-glycerine TP1-technological procedure of preparation in one extrusion step where all components were dosed to a main hopper of the twin-screw extruder, and excessive humidity was removed using vacuum prior to output of hot-melt from the extruder. After output from the extruder, hot-melt was cooled by air and granulated. TP2-technological procedure where at first, during the first extrusion step, the dryblend consist of starch, water-free glycerine and PLA was blended in the twin-screw extruder in such a way that all components were fed to a main hopper of the extruder, excessive humidity was removed from hot-melt by vacuum prior to output from extruder, and the blend was cooled by air and then granulated. The pellets were fed during the second extrusion step to the main hopper together with PHB. Prior to output from extruder, hot-melt was cleared of excessive humidity via vacuum degassing, and after output from extruder, it was cooled by air and granulated. TP3-technological procedure where at first, during the first extrusion step, thermoplastic starch alone is prepared in a twin-screw extruder. Excessive humidity is removed by vacuum prior to output of hot-melt from the extruder, and after granulation, TPS prepared in such a way is fed during the second extrusion step, together with PLA and PHB, to a main hopper. After cooling by air, the hot-melt is granulated.

[0090] Then, the cast films of 0.04 mm thickness are prepared by chill-roll technology, according to the procedure mentioned in the invention description. The mechanical properties given in Table 3 were measured.

TABLE-US-00003 TABLE 3 Mechanical properties of the reference blends prepared according to Table 1 & 2. No. of .sub.M .sub.b blend (A):(D) F:[(A) + (D)] [MPa] [%] 1 80:20 0 7.3 1.4 2 40:60 0 n/a n/a 3 5:95 0 n/a n/a 4 95:5 0 13.4 1.1 5 80:20 0 12.7 1.2 6 40:60 0 n/a n/a 7 5:95 0 n/a n/a 8 95:5 0 11.2 1.1 9 80:20 0 1.4 1.1 10 40:60 0 n/a n/a 11 5:95 15:85 n/a n/a 12 80:20 15:85 4.5 71 13 40:60 15:85 1.7 9 14 5:95 15:85 n/a n/a 15 95:5 15:85 9.2 89 16 40:60 15:85 1.6 8 17 5:95 15:85 n/a n/a 18 95:5 15:85 6.5 63 19 40:60 15:85 4 7 20 5:95 15:85 3 4 .sub.M-tensile strength .sub.b-relative elongation at break n/a-measurement cannot be performed as a film cannot be produced from a blend

Example 1

[0091] According to the invention, blends without component (F) are prepared in accordance with the technological procedure labelled as PROCEDURE PA. Composition of these blends is mentioned in Table 4, and their mechanical properties in Table 5.

[0092] The blends in the first as well as second mixing step are mixed using an extruder with the following construction parameters: [0093] A co-rotating twin-screw extruder whose screws overlap each other Screw diameter 26 mm [0094] L/D ratio=40, [0095] and blending was carried out under technological conditions as follow: [0096] Hot melt temperature: 190 C. [0097] Screw revolutions (rate): 250 rev/min [0098] First extrusion step without degassing [0099] Second extrusion step with vacuum degassing on the last but one zone of extruder [0100] Round cross section of die die [0101] Cooling of hot-melt by stream of air, and the next granulation of the cooled strand by a rotation granulator [0102] Preparation of testing pieces, and conditions of measurement of mechanical properties are mentioned in description of the invention.

TABLE-US-00004 TABLE 4 Composition of blends without plasticizer with a modifier No. of F:[(A) + Starch:[(A) + (E):[Starch + blend (A):(D) (D)] (D)] (C):Starch (C)] 21 95:5 0 30:70 30:70 1,1:100 22 80:20 0 30:70 30:70 1,1:100 23 40:60 0 30:70 30:70 1,1:100 24 5:95 0 30:70 30:70 1,1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch-corn starch (C)-glycerine (E)-phthalic anhydride

TABLE-US-00005 TABLE 5 Mechanical properties of the blends prepared according to Table 4 No. of .sub.M .sub.b Blend (A):(D) [MPa] [%] 21 95:5 48.9 3.3 22 80:20 41.7 3.4 23 40:60 41.1 2.2 24 5:95 27.5 2.1

Example 2

[0103] According to the invention, the blends mentioned in Table 8 are prepared in accordance with the technological procedure described as PROCEDURE PB. The technological conditions used correspond to Example 1.

TABLE-US-00006 TABLE 8 Composition of blends with a plasticizer and with a modifier No. of F:[(A) + Starch:[(A) + (E):[Starch + blend (A):(D) (D)] (D)] (C):Starch (C)] 25 95:5 15:85 30:70 30:70 1.1:100 26 80:20 15:85 30:70 30:70 1.1:100 24 5:95 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch-corn starch (C)-glycerine (E)-phthalic anhydride [0104] Table 11 includes properties of the blends prepared according to Table 8

TABLE-US-00007 TABLE 11 Properties of the blends prepared according to Tab. 8. No. of .sub.M .sub.b Blend (A):(D) [MPa] [%] 25 95:5 22.3 304 26 80:20 22.1 316 27 5:95 26.1 105

Example 3

[0105] According to the invention, the blends mentioned in Table 13 are prepared in accordance with the technological procedure described as PROCEDURE PC. The technological conditions used correspond to Example 1.

TABLE-US-00008 TABLE 13 Composition of the mixtures with different content of modifier No. of F:[(A) + Starch:[(A) + (E):[Starch + blend (A):(D) (D)] (D)] (C):Starch (C)] 28 80:20 0 30:70 30:70 0.1:100 29 80:20 0 30:70 30:70 0.5:100 30 80:20 0 30:70 30:70 1.0:100 31 80:20 0 30:70 30:70 2.0:100 32 80:20 0 30:70 30:70 5.0:100 33 80:20 0 30:70 30:70 10.0:100 34 80:20 15:85 30:70 30:70 0.05:100 35 80:20 15:85 30:70 30:70 0.23:100 36 80:20 15:85 30:70 30:70 0.46:100 37 80:20 15:85 30:70 30:70 2.75:100 38 80:20 15:85 30:70 30:70 5.00:100 39 80:20 15:85 30:70 30:70 6.88:100 40 80:20 15:85 30:70 30:70 9.18:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch-corn starch (C)-glycerine (E)-phthalic anhydride

[0106] Table 14 includes mechanical properties of the blends prepared according to Table 13.

TABLE-US-00009 TABLE 14 Mechanical properties of the blends prepared according to Tab. 13 No. of .sub.M .sub.b blend (A):(D) F:[(A) + (D)] (E):[Starch + (C)] [MPa] [%] 28 80:20 0 0.1:100 44.0 2.2 29 80:20 0 0.5:100 45.0 2.3 30 80:20 0 1.0:100 38.4 2.5 31 80:20 0 2.0:100 41.1 2.5 32 80:20 0 5.0:100 41.8 3.1 33 80:20 0 10.0:100 36.9 3.5 34 80:20 15:85 0.05:100 10.3 110 35 80:20 15:85 0.23:100 11.6 112 36 80:20 15:85 0.46:100 13.8 159 37 80:20 15:85 2.75:100 14.7 270 38 80:20 15:85 5.00:100 12.1 255 39 80:20 15:85 6.88:100 12.1 265 40 80:20 15:85 9.18:100 12.0 253

Example 4

[0107] According to the invention, blends corresponding to Table 15 are prepared in accordance with the technological procedure mentioned as PROCEDURE PA. The technological conditions used correspond to Example 1, mechanical properties of the blends are mentioned in Table 16.

TABLE-US-00010 TABLE 15 Composition of blends with various content of a plasticizer from the group (F) No. of F:[(A) + Starch:[(A) + (E):[Starch + blend (A):(D) (D)] (D)] (C):Starch (C)] 41 80:20 15:85 30:70 5:95 1.1:100 42 80:20 15:85 30:70 10:90 1.1:100 43 80:20 15:85 30:70 15:85 1.1:100 44 80:20 15:85 30:70 20:80 1.1:100 45 80:20 15:85 30:70 30:70 1.1:100 46 80:20 15:85 30:70 50:50 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch-corn starch (C)-glycerine (E)-phthalic anhydride

TABLE-US-00011 TABLE 16 Mechanical properties of the blends prepared according to Tab. 15 No. of .sub.M .sub.b Mixture (C):Starch [MPa] [%] 41 5:95 10.8 196 42 10:90 13.3 215 43 15:85 17.2 250 44 20:80 15.6 257 45 30:70 23.4 299 46 50:50 14.9 337

Example 5

[0108] According to the invention, the blends corresponding to Table 17 are prepared in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1. The blends are with different types of modifiers from the group (E) according to Table 17, and their mechanical properties are listed in Table 18.

TABLE-US-00012 TABLE 17 Composition of blends with different types of modifiers from the group of substances (E) Type of No. of blend Modifier (E) (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 47 M2 80:20 15:85 30:70 30:70 1.1:100 48 M3 80:20 15:85 30:70 30:70 1.1:100 49 M4 80:20 15:85 30:70 30:70 1.1:100 50 M5 80:20 15:85 30:70 30:70 1.1:100 51 M6 80:20 15:85 30:70 30:70 1.1:100 52 M7 80:20 15:85 30:70 30:70 1.1:100 53 M8 80:20 15:85 30:70 30:70 1.1:100 54 M9 80:20 15:85 30:70 30:70 1.1:100 55 M10 80:20 15:85 30:70 30:70 1.1:100 56 M11 80:20 15:85 30:70 30:70 1.1:100 57 M12 80:20 15:85 30:70 30:70 1.1:100 58 M13 80:20 15:85 30:70 30:70 1.1:100 59 M14 80:20 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch - corn starch (C) - glycerine M2 - 1,2,3,6-Tetrahydrophthalic anhydride M3 - Trimellitic anhydride M4 - Maleic anhydride M5 - Hexahydrophthalic anhydride M6 - Toluene-2,4-diisocyanate dimer M7 - 4,4-Diphenylmethane diisocyanate M8 - Epoxidized styrene and methylmethacrylate copolymer, Mw 6800 g/mol, EEW* = 285 g/mol M9 - Citric anhydride M10 - Succinic anhydride M11 - Citric acid M12 - Adipic acid M13 - Hexamethylene diisocyanate M14 - Pyromellitic dianhydride *EEW = epoxy equivalent weight

TABLE-US-00013 TABLE 18 Mechanical properties of the blends prepared according to Tab. 17 No. of Type of .sub.M .sub.b blend Modifier (E) [MPa] [%] 47 M2 10.9 251 48 M3 18.6 255 49 M4 21.0 306 50 M5 11.5 200 51 M6 11.7 189 52 M7 12.1 188 53 M8 11.4 181 54 M9 23.5 334 55 M10 17.9 303 56 M11 21.2 324 57 M12 10.1 153 58 M13 12.0 238 59 M14 20.0 322

Example 6

[0109] According to the invention, blends are prepared in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1. The blends are with different types of PLAs from the group (A) according to Table 19. Their mechanical properties are summarized in Table 20.

TABLE-US-00014 TABLE 19 Composition of blends with different types of PLAs from the group (A) No. of blend Type of PLAs (A) (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 60 PLA 1 80:20 15:85 30:70 30:70 1.1:100 45 PLA 2 80:20 15:85 30:70 30:70 1.1:100 61 PLA 3 80:20 15:85 30:70 30:70 1.1:100 62 PLA 4 80:20 15:85 30:70 30:70 1.1:100 63 PLA 5 80:20 15:85 30:70 30:70 1.1:100 64 PLA 6 80:20 15:85 30:70 30:70 1.1:100 65 PLA 7 80:20 15:85 30:70 30:70 1.1:100 66 PLA 8 80:20 15:85 30:70 30:70 1.1:100 67 PLA 6:PLA 4 1:1 80:20 15:85 30:70 30:70 1.1:100 68 PLA 7:PLA 1 1:1 80:20 15:85 30:70 30:70 1.1:100 69 PLA 3:PLA 4 1:1 80:20 15:85 30:70 30:70 1.1:100 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch - corn starch (C) - glycerine (E) - phthalic anhydride (A) - type of PLA: Mw Index of Content of D- .sub.M .sub.b (A) - Type of PLA kDa Polydispersity isomer [MPa] [%] PLA 1 202 2.18 4.20% 44.3 8.9 PLA 2 193 2.18 8% 43.4 3.7 PLA 3 140 1.9 2% 56.8 2.5 PLA 4 188 1.8 12% 37.9 4.7 PLA 5 200 1.8 2% 58.3 2.3 PLA 6 162 1.81 <1% 54.8 2.2 PLA 7 187 1.95 <1% 48.4 4.1 PLA 8 195 1.98 4% 46.9 2.4 Note: The table summarizes mechanical properties of the films prepared according to procedure included in the invention description, the part Testing pieces for mechanical properties measurements, and their preparation, from alone PLAs, with no additives.

TABLE-US-00015 TABLE 20 Mechanical properties of the blends prepared according to Tab. 19 No. of Type of PLA .sub.M .sub.b blend (A) [MPa] [%] 60 PLA 1 16.0 276 45 PLA 2 23.4 299 61 PLA 3 16.9 291 62 PLA 4 18.8 390 63 PLA 5 19.8 338 64 PLA 6 17.3 308 65 PLA 7 18.7 328 66 PLA 8 16.1 307 67 PLA 6: 16.4 333 PLA 4 1:1 68 PLA 7: 14.2 289 PLA 1 1:1 69 PLA 3: 16.2 326 PLA 4 1:1

Example 7

[0110] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1, blends were prepared with different types of plasticizers from the group (F) according to Table 21. Their mechanical properties are listed in Table 22.

TABLE-US-00016 TABLE 21 Composition of blends with different types of plasticizer PLA from the group (F) Type of No. of blend Plasticizer (F) (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 45 F 1 80:20 15:85 30:70 30:70 1.1:100 70 F 2 80:20 15:85 30:70 30:70 1.1:100 71 F 3 80:20 15:85 30:70 30:70 1.1:100 72 F 4 80:20 15:85 30:70 30:70 1.1:100 73 F 5 80:20 15:85 30:70 30:70 1.1:100 74 F 6 80:20 15:85 30:70 30:70 1.1:100 75 F 7 80:20 15:85 30:70 30:70 1.1:100 76 F 8 80:20 15:85 30:70 30:70 1.1:100 77 F 9 80:20 15:85 30:70 30:70 1.1:100 78 F 10 80:20 15:85 30:70 30:70 1.1:100 79 F 11 80:20 15:85 30:70 30:70 1.1:100 80 F 12 80:20 15:85 30:70 30:70 1.1:100 81 F 13 80:20 15:85 30:70 30:70 1.1:100 82 F 14 80:20 15:85 30:70 30:70 1.1:100 83 F 15 80:20 15:85 30:70 30:70 1.1:100 84 F 16 80:20 15:85 30:70 30:70 1.1:100 85 F 17 80:20 15:85 30:70 30:70 1.1:100 86 F 18 80:20 15:85 30:70 30:70 1.1:100 87 F 19 80:20 15:85 30:70 30:70 1.1:100 88 F 20 80:20 15:85 30:70 30:70 1.1:100 89 F 21 80:20 15:85 30:70 30:70 1.1:100 90 F 22 80:20 15:85 30:70 30:70 1.1:100 91 F 23 80:20 15:85 30:70 30:70 1.1:100 92 F 24 80:20 15:85 30:70 30:70 1.1:100 93 F 25 80:20 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 Starch - corn starch (C) - glycerine (E) - phthalic anhydride (F) type of plasticizer for PLA and/or PHA: (F) Plasticizer Type Chemical Name Viscosity at 25 C. mPas F1 Acetyltributylcitrate 33 F2 Tributylcitrate 25 F3 Tris-(2-ethylhexyl)-o-acetylcitrate 85 F4 Triacetine 16 F5 Oligoester of adipic acid 3015 F6 Oligoester of adipic acid 4082 F7 Oligoester of adipic acid 589 F8 Oligoester of adipic acid 1041 F9 Di-octyl terephtalate 64 F10 Di-octyl adipate 12 F11 Diisononyl phthalate 55 F12 Oligoester of adipic acid 19890 F13 F1/F3 60:40 45 F14 F1/F3 50:50 48 F15 F1/F3 87:13 37 F16 F1/F3 83:17 36 F17 F1/F2 67:33 29 F18 F1/F4 67:33 24 F19 F2/F3 50:50 40 F20 F2/F1/F3 50:30:20 31 F21 F2/F1 50:50 28 F22 F1/F7 67:33 140 F23 F1/F8 67:33 178 F24 F1/F5 67:33 350 F25 F1/F8 67:33 427

TABLE-US-00017 TABLE 22 Mechanical properties of the blends prepared according to Tab. 21 Type of No. of Plasticizer .sub.M .sub.b blend (F) [MPa] [%] 45 F 1 23.4 299 70 F 2 16.0 304 71 F 3 16.4 302 72 F 4 10.6 215 73 F 5 16.0 335 74 F 6 17.9 365 75 F 7 19.5 198 76 F 8 15.9 249 77 F 9 16.8 198 78 F 10 10.2 168 79 F 11 24.6 183 80 F 12 18.1 178 81 F 13 27.0 356 82 F 14 16.5 352 83 F 15 23.5 346 84 F 16 17.1 308 85 F 17 26.5 250 86 F 18 24.4 284 87 F 19 20.17 302 88 F 20 24.4 284 89 F 21 20.17 302 90 F 22 22.0 306 91 F 23 17.0 322 92 F 24 18.1 337 93 F 25 17.1 334

Example 8

[0111] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1, blends with different types of starch were prepared according to Table 23. Their mechanical properties are listed in Table 24.

TABLE-US-00018 TABLE 23 Composition of the blends with different types of starch No. of blend Type of Starch (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 45 Com 80:20 15:85 30:70 30:70 1.1:100 94 Amaranth 80:20 15:85 30:70 30:70 1.1:100 95 Potato 80:20 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate (C) - glycerine (E) - phthalic anhydride

TABLE-US-00019 TABLE 24 Mechanical properties of the blends prepared according to Tab. 23 No. of Type of .sub.M .sub.b blend Starch [MPa] [%] 45 Corn 23.4 299 94 Amaranth 11.9 113 95 Potato 19.4 328

Example 9

[0112] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1, blends with different types of plasticizers from the group (C) were prepared according to Table 25, and their mechanical properties are listed in Table 26.

TABLE-US-00020 TABLE 25 Composition of blend with different types of plasticizers from the group (C) Type of No. of blend Plasticizer (C) (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 45 Glycerin 80:20 15:85 30:70 30:70 1.1:100 96 PEG 300 80:20 15:85 30:70 30:70 1.1:100 97 PEG 600 80:20 15:85 30:70 30:70 1.1:100 98 PEG 1000 80:20 15:85 30:70 30:70 1.1:100 99 MPG 80:20 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch - corn starch (C) - glycerine (E) - phthalic anhydride

TABLE-US-00021 TABLE 26 Mechanical properties of the blends prepared according to Tab. 25 Type of No. of Plasticizer .sub.M .sub.b blend (C) [MPa] [%] 45 Glycerine 23.4 299 96 PEG 300 12.1 257 97 PEG 600 11.9 234 98 PEG 1000 13.8 211 99 MPG 10.6 244

Example 10

[0113] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1, blends with different types of component (D)PHA were prepared according to Table 27. Their mechanical properties are summarized in Table 28.

TABLE-US-00022 TABLE 27 Composition of blends with different types of component (D) - various types of PHA Type of PHA No. of blend (D) (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 45 PHA 1 80:20 15:85 30:70 30:70 1.1:100 100 PHA 2 80:20 15:85 30:70 30:70 1.1:100 101 PHA 3 80:20 15:85 30:70 30:70 1.1:100 102 PHA 4 80:20 15:85 30:70 30:70 1.1:100 103 PHA 5 80:20 15:85 30:70 30:70 1.1:100 104 PHA 6 80:20 15:85 30:70 30:70 1.1:100 105 PHA 7 80:20 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (F) acetyltributylcitrate Starch - corn starch (C) - glycerine (E) - phthalic anhydride (D) - type of PHA: Co-monomer .sub.M .sub.b Type of PHA (D) PHA Mw D index Content (%) [MPa] [%] PHA 1 P3HB 608 4.23 14.8 1.4 PHA 2 P3HB4HV 460 4.53 3.1% 4HV 27.0 3.5 PHA 3 P3HB4HV 539 4.65 5.1% 4HV 12.3 4.8 PHA 4 P3HB 428 3.54 34.5 2.6 PHA 5 P3HB 652 5.4 34.8 2.6 PHA 6 P3HB 780 3.2 33.9 2.1 PHA 7 P3HB4HB 223 3.35 17.6% 4HB 28.7 2.3 Note: The table contains mechanical properties of the films prepared according to the procedure included in the invention description, the part Testing pieces for mechanical properties mesurements, and their preparation, from alone PLAs, with no additives.

TABLE-US-00023 TABLE 28 Mechanical properties of the blends prepared according to Tab. 27 No. of Type of PHA .sub.M .sub.b blend (D) [MPa] [%] 45 PHA 1 23.4 299 100 PHA 2 19.9 287 101 PHA 3 19.0 264 102 PHA 4 18.7 302 103 PHA 5 19.2 286 104 PHA 6 20.2 298 105 PHA 7 12.3 114

Example 11

[0114] According to the invention, blends are prepared in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1. The blends with addition of nucleation agents from the group of substances (G) were prepared according to Table 29, their mechanical properties are listed in Table 30. The nucleation agents from the group of substances (G) were added according to procedure PA, to a hopper during the second extrusion step PA2.

TABLE-US-00024 TABLE 29 Composition of blends with addition of nucleation agents Type and Content No. of of Nucleation Agent blend (G) (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 106 B, 1 % 80:20 0:100 30:70 30:70 1.1:100 107 M, 1 % 80:20 0:100 30:70 30:70 1.1:100 108 B, 1 % 40:60 0:100 30:70 30:70 1.1:100 109 M, 1 % 40:60 0:100 30:70 30:70 1.1:100 110 B, 1 % 80:20 15:85 30:70 30:70 1.1:100 111 M, 1 % 80:20 15:85 30:70 30:70 1.1:100 112 B, 1 % 40:60 15:85 30:70 30:70 1.1:100 113 M, 1 % 40:60 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch - corn starch (C) - glycerine (E) - phthalic anhydride M - Talc, substance from the group (G) as a nucleation agent B - Boron nitride, substance from the group (G) as a nucleation agent

TABLE-US-00025 TABLE 30 Mechanical properties of the blends prepared according to Tab. 29 Type and Content of Nucleation No. of Agent .sub.M .sub.b blend (G) F:[(A) + (D)] [MPa] [%] 106 B, 1% 0:100 29.7 2.1 107 M, 1% 0:100 30.2 2.8 108 B, 1% 0:100 33.8 3.7 109 M, 1% 0:100 35.0 2.9 110 B, 1% 15:85 18.1 275 111 M, 1% 15:85 18.2 180 112 B, 1% 15:85 15.1 180 113 M, 1% 15:85 15.3 260

Example 12

[0115] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA: Under technological conditions corresponding to Example 1, blends with addition of fillers according to Table 31 were prepared, and their mechanical properties are listed in Table 32. The fillers from the group (G) were added according to procedure PA to a hopper, during the second extrusion step PA2.

TABLE-US-00026 TABLE 31 Composition of blends containing fillers Type and Content No. of of Nucleation Agent blend (G) (A):(D) F:[(A) + (D)] Starch:[(A) + (D)] (C):Starch (E):[Starch + (C)] 114 P1, 10 % 80:20 0:100 30:70 30:70 1.1:100 115 P2, 10 % 80:20 0:100 30:70 30:70 1.1:100 116 P1, 10 % 40:60 0:100 30:70 30:70 1.1:100 117 P2, 10 % 40:60 0:100 30:70 30:70 1.1:100 118 P1, 10 % 80:20 15:85 30:70 30:70 1.1:100 119 P2, 10 % 80:20 15:85 30:70 30:70 1.1:100 120 P1, 10 % 40:60 15:85 30:70 30:70 1.1:100 121 P2, 10 % 40:60 15:85 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starch - corn starch (C) - glycerine (E) - phthalic anhydride P1 - Clay, filler from the group (G), calculated 10 wt % on the whole blend P2 - Calcium carbonate, filler from the group (G), calculated 10 wt % on the whole blend

TABLE-US-00027 TABLE 32 Mechanical properties of the blends prepared according to Tab. 29 Typ and Content of No. of Filler .sub.M .sub.b blend (G) (A):(D) F:[(A) + (D)] [MPa] [%] 114 P1, 10% 80:20 0:100 30.6 2.9 115 P2, 10% 80:20 0:100 29.5 2.8 116 P1, 10% 40:60 0:100 29.3 3.2 117 P2, 10% 40:60 0:100 48.7 3.2 118 P1, 10% 80:20 15:85 15.1 255 119 P2, 10% 80:20 15:85 21.3 272 120 P1, 10% 40:60 15:85 12.5 201 121 P2, 10% 40:60 15:85 14.6 282

Example 13

[0116] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA, under technological conditions corresponding to Example 1, and technological procedure TP1 mentioned in Example 2, the blends were prepared with different content of starch according to Table 33. Mechanical properties are listed in Table 34.

TABLE-US-00028 TABLE 33 Composition of the blends with different content of starch No. of F: Starch: (C): (E): blend (A):(D) [(A) + (D)] [(A) + (D)] Starch [Starch + (C)] 122 80:20 15:85 3:97 30:70 1,1:100 123 80:20 15:85 10:90 30:70 1,1:100 124 80:20 15:85 20:80 30:70 1,1:100 45 80:20 15:85 30:70 30:70 1,1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starchcorn starch (C)glycerine (E)phthalic anhydride

TABLE-US-00029 TABLE 34 Mechanical properties of the blends prepared according to Tab. 33 No. of Starch: (E): .sub.M .sub.b blend [(A) + (D)] [Starch + (C)] [MPa] [%] 122 3:97 1,1:100 32.6 328 123 10:90 1,1:100 28.7 326 124 20:80 1,1:100 25.9 329 45 30:70 1,1:100 23.4 299

Example 14

[0117] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA: under technological conditions corresponding to Example 1, the blends with different types of plasticizers from the group (F) according to Table 35 were prepared. Their mechanical properties are listed in Table 36.

TABLE-US-00030 TABLE 35 Composition of the blends with vanous content of a plasticizer from the group (F) No. of F: Starch: (C): (E): blend (A):(D) [(A) + (D)] [(A) + (D)] Starch [Starch + (C)] 22 80:20 0:100 30:70 30:70 1.1:100 125 80:20 10:90 30:70 30:70 1.1:100 126 80:20 13:87 30:70 30:70 1.1:100 127 80:20 15:85 30:70 30:70 1.1:100 128 80:20 20:80 30:70 30:70 1.1:100 129 80:20 25:75 30:70 30:70 1.1:100 130 80:20 33:67 30:70 30:70 1.1:100 131 80:20 30:70 30:70 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate, for the blend No. 131 plasticizer F14 from example 7 was used Starchcorn starch (C)glycerine (E)phthalic anhydride

TABLE-US-00031 TABLE 36 Mechanical properties of the blends prepared according to Tab. 35 No. of .sub.M .sub.b blend F:[(A) + (D)] [MPa] [%] 22 0:100 41.7 2.3 125 10:90 18.8 372 126 13:87 31.4 130 127 15:85 26.7 309 128 20:80 18.4 252 129 25:75 18.1 253 130 33:67 12.5 150 131 30:70 14.8 151

Example 15

[0118] According to the invention, in accordance with the technological procedure mentioned as PROCEDURE PA: under the technological conditions corresponding to Example 1, the blends according to Table 37 were prepared, wherein during the extrusion step PA2, a head for production of films, and a chill roll unit were attached directly to the twin-screw extruder. Samples for mechanical properties measurements were prepared by the chill roll technology. The mechanical properties are listed in Table 38.

TABLE-US-00032 TABLE 37 Composition of the blends with different content of starch No. of F: Starch: (C): (E): blend (A):(D) [(A) + (D)] [(A) + (D)] Starch [Starch + (C)] 132 80:20 15:85 40:60 30:70 1.1:100 133 80:20 15:85 50:50 30:70 1.1:100 134 80:20 15:85 50:50 30:70 1.1:100 135 80:20 15:85 50:50 30:70 1.1:100 136 80:20 15:85 60:40 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 8% Mw = 193 kDa, polydispersity coefficient D = 2.18 (D) P3HB, Mw = 608 kDa, polydispersity coefficient D = 4.23 (F) acetyltributylcitrate Starchcorn starch (C)glycerine (E)phthalic anhydride

TABLE-US-00033 TABLE 38 Mechanical properties of the blends prepared according to Tab. 37 No. of Starch: .sub.M .sub.b blend [(A) + (D)] (C):Starch [MPa] [%] 132 40:60 30:70 21.1 346 133 50:50 30:70 12.5 302 134 50:50 25:75 13.1 301 135 50:50 20:80 11.5 184 136 60:40 30:70 3.6 235

Example 16

[0119] According to the invention, according to the technological procedure mentioned as PROCEDURE PA: under the technological conditions corresponding to Example 1, the blends according to Table 38 were prepared, wherein during the extrusion step PA2, a head for production of films, and a chill roll unit were attached directly to the twin-screw extruder. Samples for mechanical properties measurements were prepared by the chill roll technology. The mechanical properties are listed in Table 39.

TABLE-US-00034 TABLE 38B Composition of blends with various content of a plasticizer from the group (F) No. of F: Starch: (C): (E): blend (A):(D) [(A) + (D)] [(A) + (D)] Starch [Starch + (C)] 137 80:20 7:93 40:60 30:70 1.1:100 138 60:40 7:93 40:60 30:70 1.1:100 139 80:20 7:93 40:60 30:70 1.1:100 140 60:40 7:93 40:60 30:70 1.1:100 (A) D,L-PLA, content of D-isomer = 12% Mw = 188 kDa, polydispersity coefficient D = 1.8 (D) P3HB, Mw = 708 kDa, polydispersity coefficient D = 3.2 (F)F6 from Example 7; oligoester of adipic acid, viscosity at 25 C. mPas Starchcorn starch (C)glycerine (E)phthalic anhydride

TABLE-US-00035 TABLE 39 Mechanical properties of the blends prepared according to Tab. 38B No. of .sub.M .sub.b blend (A):(D) F:[(A) + (D)] [MPa] [%] 137 80:20 7:93 18.1 268 138 60:40 7:93 12.0 149 139 80:20 7:93 20.2 181 140 60:40 7:93 13.3 115

INDUSTRIAL APPLICABILITY

[0120] A solution according to the present invention provides production of a biodegradable polymer blend consisting of thermoplastic starch and polyhydroxyalkanoate, wherein the blend has enhanced mechanical properties. The biodegradable polymer blend is ecological and cost-effective, with potential applications mainly in the agriculture and packaging industry sectors.