Mechanically reinforced, transparent, anti-biofouling thermoplastic resin composition and manufacturing method thereof

Abstract

This invention discloses a transparent standalone resin or masterbatch concentrate composition and manufacturing method of transforming commercial transparent grade base thermoplastics into anti-biofouling resins through extrusion or any similar hot melt mixing processes. The re-compound solids enable a number of product reforming processes, including but not limited to thermoforming, profile extrusion, injection molding, blow molding, blow filming, film casting, and spinning into articles of different shapes and geometries or overmolding on plastic substrates that can resist surface adsorption of microbes, mammalian cells, proteins, peptides, nucleic acids, steroids and other cellular constituents after solidification. The articles formed thereof additionally exhibit mechanical reinforcement and no leaching while retain the optical clarity of the base thermoplastics in the same product form as quantified in terms of the light transmittance and haze.

Claims

1. A method for modifying a transparent grade base thermoplastic to enable biofouling resistance and mechanical reinforcement of an article formed therefrom against fluid biological matters in standalone solid or masterbatch concentrate form, said method comprising: (a) providing said transparent grade base thermoplastic to form a composition, wherein said transparent grade base thermoplastic comprises transparent grade polypropylene random copolymer or transparent grade methyl methacrylate butadiene styrene; (b) either blending said transparent grade base thermoplastic with a non-ionic surfactant, with or without impact modifiers, and with other additives directly or blending a masterbatch concentrate comprising said transparent grade base thermoplastic, said non-ionic surfacant, other additives, and optionally impact modifiers with a diluted form of said transparent grade base thermoplastic in order to form said composition, wherein said non-ionic surfactant is selected from the group consisting of fatty alcohol polyoxyalkylene ethers, polyoxyalkylene sorbitan/sorbitol fatty acid esters, polyoxyalkylene alkyl amines, and polether glycols, said impact modifiers are selected from the group consisting of polyolefin elastomers (POE) and thermoplastic polyurethane (TPU), and said other additives comprise one or more initiators, cross-linking agents, nucleators, anti-oxidants, or an auxiliary additive, wherein said initiators are selected from the group consisting of tosylic acid, tetramethylammonium hydroxide, and an organic peroxide selected from the group consisting of dicumyl peroxide, bis(tert-butylperoxyisopropyl) benzene, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, and benzoyl peroxide, and said cross-linking agents are selected from the group consisting of triallyl isocyanurate, N,N-m-phenylene bismaleimide, and sulfur, and said auxiliary additive is alumnia nanoparticles; (c) melt processing said composition; (d) pelletizing said composition after said melting processing to form pellets; and (e) molding said pellets into article with desired shape and dimension.

2. The method of claim 1, wherein said melt processing comprises extrusion or hot melt mixing.

3. The method of claim 1, wherein said molding comprises profile extrusion, injection molding, blow molding, blow filming, film casting, spinning and overmolding on plastic substrates.

4. The method of claim 1, wherein said melt processing is carried out under a temperature ranging from 150 to 250 C.

5. The method of claim 1, wherein said melt processing is carried out under a temperature from 170 to 220 C.

6. The method of claim 1, wherein said transparent grade base thermoplastic and said pellets after melt processing has deviation of haze lower than 20% at 1 mm thickness under the standard of ASTM D1003.

7. The method of claim 1, wherein said non-ionic surfactant is selected from the group consisting of polyethylene glycol (PEG) sorbitol hexaoleate, AEO-5 and polyetheramine.

8. The method of claim 7, wherein said PEG sorbitol hexaoleate has an average molecular weight from 2000 to 20,000 Da.

9. The method of claim 7, wherein said polyetheramine has a molecular weight from 200 to 6,000 Da.

10. The method of claim 1, wherein said polyetheramine is selected from the group consisting of: ##STR00001## wherein x is 2.5 and a+b+c is 85.

11. The method of claim 1, wherein said non-ionic surfactants has a weight percentage from 0.5 wt % to 10 wt %.

12. The method of claim 1, wherein said polyolefin elastomer is a propylene-ethylene elastomer or an ethylene-octene elastomer.

13. The method of claim 1, wherein said impact modifiers have a weight concentration from 0.1 to 30 wt %.

14. The method of claim 1, wherein said nucleators are selected from the group consisting of: ##STR00002## in a concentration from 0.1 to 3 wt %.

15. The method of claim 1, wherein said anti-oxidants are selected from the group consisting of: butylated hydroxytoluene, ##STR00003## and a 1:1 mixture of ##STR00004##

16. The method of claim 1, wherein said cross-linking agents have a weight percentage from 0.01 to 0.2 wt %.

17. The method of claim 1, wherein said nucleators have a weight percentage from 0.1 to 3 wt %.

18. The method of claim 1, wherein said anti-oxidants have a weight concentration from 0.1 to 2 wt %.

19. The method of claim 1, wherein said auxiliary additives have a weight percentage from 0.1 to 4 wt %.

20. The method of claim 1, wherein said masterbatch concentrate is formed by extruding said transparent grade base thermoplastic, said non-ionic surfactant, other additives and optionally said impact modifiers prior to said blending of the masterbatch concentrate with a diluted form of said transparent grade base thermoplastic.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

(2) FIG. 1 is a schematic diagram showing an incubation protocol for microbial adsorption tests on different molded circular plate samples reformed by injection molding from the melt processed composition comprising the modified transparent grade base thermoplastics according to certain embodiments of the present invention.

(3) FIG. 2 is an illustration of the main components in the composition for modifying the transparent grade base thermoplastics according to certain embodiment of the present invention.

(4) FIG. 3 is a schematic diagram showing a workflow of both one-step and two-step methods for modifying the transparent grade base thermoplastics according to certain embodiments of the present invention.

(5) FIG. 4 illustrates the test results of the molded plate samples made of one of the modified transparent grade base thermoplastics (MBS-M) against a control (MBS): (A) is an image of molded MBS vs MBS-M plate samples placed on top of a piece of paper; (B) shows microbial adsorption test of the molded MBS vs MBS-M circular plate samples by an image taken from aerial view. The left three sets of image represents the microbial adsorption of MBS towards Escherichia Coli, and the right three sets of image represents the microbial adsorption of MBS towards Staphylococcus Aureus.

(6) FIG. 5 illustrates the test results of the molded plate samples made of one of the modified transparent grade base thermoplastics (PPM-M) against a control (PPM): (A) is an image of molded PPM vs PPM-M plate samples placed on top of a piece of paper; (B) is an image of molded PPM vs PPM-M plate samples after being tested in a protein repellent assay according to the protocol as described hereinafter; (C) shows microbial adsorption test of the molded PPM vs PPM-M circular plate samples by an image taken from aerial view. The left three sets of image represents the microbial adsorption of PPM towards Escherichia Coli, and the right three sets of image represents the microbial adsorption of PPM towards Staphylococcus Aureus.

DETAILED DESCRIPTION OF THE INVENTION

(7) References in the specification to one embodiment, an embodiment, an example embodiment, etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

(8) Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a concentration range of about 0.1% to about 5% should be interpreted to include not only the explicitly recited concentration of about 0.1 wt. % to about 5 wt. %, but also the individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, and 3.3% to 4.4%) within the indicated range.

(9) As described herein, the terms a or an are used to include one or more than one and the term or is used to refer to a nonexclusive or unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Furthermore, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

(10) In the methods of manufacturing described herein, the steps can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Recitation in a claim to the effect that first a step is performed, and then several other steps are subsequently performed, shall be taken to mean that the first step is performed before any of the other steps, but the other steps can be performed in any suitable sequence, unless a sequence is further recited within the other steps. For example, claim elements that recite Step A, Step B, Step C, Step D, and Step E shall be construed to mean step A is carried out first, step E is carried out last, and steps B, C, and D can be carried out in any sequence between steps A and E, and that the sequence still falls within the literal scope of the claimed process. A given step or sub-set of steps can also be repeated.

(11) Furthermore, specified steps can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed step of doing X and a claimed step of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

(12) Definitions

(13) The singular forms a, an and the can include plural referents unless the context clearly dictates otherwise.

(14) The term about can allow for a degree of variability in a value or range, for example, within 10%, or within 5% of a stated value or of a stated limit of a range.

(15) The term independently selected from refers to referenced groups being the same, different, or a mixture thereof, unless the context clearly indicates otherwise. Thus, under this definition, the phrase X1, X2, and X3 are independently selected from noble gases would include the scenario where, for example, X1, X2, and X3 are all the same, where X1, X2, and X3 are all different, where X1 and X2 are the same but X3 is different, and other analogous permutations.

(16) Detailed Descriptions of Preferred Embodiments

(17) The present invention is not to be limited in scope by any of the following descriptions. The following examples or embodiments are presented for exemplification only.

(18) The modification of the transparent grade base thermoplastics according to the present invention can be processed in either one-step or two-step method (FIG. 3). The transparent grade base polymer is blended or reacted with chemical modifiers and/or auxiliary additives either before or during extrusion to create functional polymer (one-step) or masterbatch (two-step). Representative examples of transparent grade base thermoplastics include (-impact modified) polypropylene random (PPR) copolymers and homopolymer (PPH) and several thermoplastic elastomers, such as methyl methacrylate butadiene styrene (MBS), styrene ethylene butylene styrene block thermoplastic elastomer (SEBS) and polyurethane. Melt processing can be achieved on either single-screw or twin-screw extruder operated with a proper processing temperature window. The extruder can be equipped with a cooling water bath and a pelletizer to obtain solid standalone or a masterbatch concentrate resin prior to article reforming by injection molding, for example. The processing temperature ranges from 170 to 220 C. for said transparent grade base thermoplastics and other main components for modifying the same.

(19) One or more of linear and/or multi-armed structures of non-ionic surfactants is/are selected as the non-fouling modifiers. The non-ionic surfactants are chosen from fatty alcohol polyoxyalkylene ethers, polyoxyalkylene sorbitan/sorbitol fatty acid esters, polyoxyalkylene alkyl amines, polyether glycols, fatty acid alkanolamides and their derivatives. Polyethylene glycol (PEG) sorbitol hexaoleate, AEO-5 and polyetheramine (JEFFAMINE D-230 or T-5000) are preferred non-fouling modifiers. Proper ratio and combination of functional modifiers is key to the anti-biofouling performance and retention of transparency of the transparent grade base thermoplastic materials. Typical ratio is adjusted from 0.5 to 10% on a weight basis with respect to the total weight of the composition. In a specific embodiment, thePEG sorbitol hexaoleate has a molecular weight ranging from 2,000 to 20,000 Da (or 2 to 20 kDa). In another specific embodiment, said polyetheramine has a molecular weight ranging from 200 to 6,000 Da.

(20) Elastomers, such as polyolefin elastomer (POE) and thermoplastic polyurethane (TPU), are chosen as impact modifiers for modifying different transparent grade base thermoplastics. VISTAMAXX and ENGAGE series POE and ELASTOLLAN series TPU are preferably suggested in this case. The suggested ratio ranges from 0.1 to 30% by weight with respect to the total weight of the composition in order to augment the impact strength. Initiators and additives including tosylic acid, tetramethylammonium hydroxide, and/or an organic peroxide, such as dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane and benzoyl peroxide, in a weight percentage from 0.01% to 0.2% with respect to the total weight of the composition are added to initiate covalent grafting of the non-fouling modifiers onto the base polymers and/or impact modifiers.

(21) Other additives, such as anti-oxidant, cross-linking agent, optical brightener, color masterbatch, odor absorbent, etc. are chosen to control the appearance and the scent of the articles. The anti-oxidant is preferred to be selected from butylated hydroxytoluene, IRGANOX 1010, IRGANOX 1076, IRGANOX 1098, IRGAFOS 168 or IRGANOX B 225 with a weight percentage to the total weight of the composition from 0.1 to 2 wt %. The cross-linking agent is preferred to be selected from triallyl isocyanurate, N,N-m-phenylene dismaleimide or sulfur with a weight percentage to the total weight of the composition from 0 to 1 wt %. The initiator is preferred to be selected from dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene or benzoyl peroxide with a weight percentage to the total weight of the composition from 0.01 to 0.2 wt %. The nucleator is preferred to be selected from MILLAD NX8000, MILLAD 3988, ADK STAB NA-18 or ADK STAB NA-25 with a weight percentage to the total weight of the composition from 0 to 3 wt %. An auxiliary additive is preferred to be alumina nanoparticles (AEROXIDE Alu C) for enhancement of the heat deflection temperature of base polymers with suggested weight percentage to the total weight of the composition from 0.1 to 4 wt %.

(22) During injection molding, the cycle time typically ranges from a few seconds to 5 minutes for extremely thick-wall parts per shot. On average, the injection falls in the range between 20 and 60 seconds for a well-designed mold and with a proper barrel and mold temperature control. For instance, samples of dogbone tensile test bars (Type I, ASTM D638), Izod impact test bars (ASTM D256), flat circular plates with thickness of 1.5 mm and diameter of 60 mm for optical haze/transmittance (ASTM D1003) and yellowness index (ASTM E313) measurement and rectangular strips for heat deflection temperature measurement (ISO 75) were produced on a 150-ton injection molding machine in one single shot from the mold cavity. Extrusive compounding was performed on a co-rotating twin-screw extruder. The extruder had a screw diameter of 26 mm, a screw length-to-diameter (L/D) ratio of 42:1 and an adjustable speed of 50-500 rpm. Its barrel was divided into 7 temperature zones, one of which was located at the die orifice. The extruder was equipped with a volumetric feeder composed of two separate compartments that can feed two different types of raw materials at an equivalent ratio.

(23) Protein repellent assay procedures are herein described as follows:

(24) (a) 0.5 ml bovine serum albumin (BSA)/0.01 M phosphate-buffered saline (0.1 g/ml, pH 7.4) protein solution is wetted on a flat surface of a molded circular plate sample;

(25) (b) The protein solution is placed at room temperature for half an hour for adsorption;

(26) (c) The protein solution is withdrawn by aspiration;

(27) (d) Bradford reagent (Cat. no. B6916, Sigma) of the same volume is deposited on the affected area to stain the potentially protein-fouled sample surface;

(28) (e) Color change of the Bradford reagent (from brown to blue) qualitatively indicates the presence of adsorbed proteins.

(29) The incubation protocol for microbial adsorption tests on the molded circular plate samples is herein described by the schematic diagram in FIG. 1. The starting inoculum concentration of E. coli (ATCC 8739) and S. aureus (ATCC 6538P) was about 0.910.sup.6 and 810.sup.8 cells/ml in 1/500 NB solution (1/500 NB refers to the 500 diluted Nutrient Broth with pH adjusted to 6.8-7.2) for challenging the sample surface. Result of the adsorption tests are illustrated in the following examples, and also in FIG. 4B and FIG. 5C.

EXAMPLES

(30) The embodiments of the present invention can be better understood by reference to the following examples which are offered by way of illustration. The present invention is not limited to the examples given herein.

Example 1

(31) The modification of MBS, a highly transparent methyl methacrylate butadiene styrene plastic compound, was rendered by extrusive compounding of 94% MBS resin with 1% IRGANOX B 225 and 5% AEO-5, a fatty alcohol ethoxylate, on a weight basis with a processing temperature ranging from 180 C. to 210 C. to obtain functional resin directly. The modified formulation was re-pelletized as standalone resin (herein annotated as MBS-M) that could be fed into an injection molding machine (with processing temperature of 210 C.) to obtain plastic samples dictated by the mold tooling design. FIG. 4A shows that the molded plate samples made of MBS-M according to the present method remain essentially transparent. The characterization results are summarized in Table 1. The impact strength of MBS-M was almost double that of the base MBS plastic apart from the added microbial repellent performance towards E. coli, a Gram-negative and S. aureus, a Gram-positive bacteria. MBS-M passed ISO 22196's antibacterial requirement by showing a nearly log-4 reduction of bacterial counts after intimate contact with corresponding molded plate samples with accredited report certificate. The plate samples also indicated zero-growth ratings consistently over 21 days under ASTM G21 and ASTM G22 standards with accredited report certificates. Besides, the total aerobic microbial count and the total combined molds and yeasts of the MBS-M pellets were less than 10 CFU/g according to USP <61> enumeration tests with accredited report certificate.

(32) TABLE-US-00001 TABLE 1 Izod % reduction % reduction Impact Elongation Mechanical of E. coli of S. aureus Transparency Haze Strength HDT at break Strength adsorption adsorption Sample (%) (%) (KJ/m.sup.2) ( C.) (%) (N/mm.sup.2) (%) (%) MBS 88.4 7.3 24.42 83.5 89.2 28.04 (Control) MBS-M 89.6 6.5 47.11 79.8 82.6 24.37 99% 96%

Example 2

(33) The modification of PPR, a transparent polypropylene random copolymer, was rendered by extrusive compounding of PPR resin with 30% polyolefin elastomer (VISTAMAXX 6202, ExxonMobil), 2% JEFFAMINE D-230, 2% poly(ethylene glycol) sorbitol hexaoleate, 3.75% alumina nanoparticles, 0.1% dicumyl peroxide, 0.05% triallyl isocyanurate and 0.01% CBS-127, an optical brightener, on a weight basis with processing temperature ranging from 170 C. to 190 C. to obtain a functional masterbatch concentrate (herein, annotated as PPR-M) after pelletization. The masterbatch was dry blended at a ratio of 1:1.5 w:w PPR with 0.1% overall by weight of NX8000 and subsequently fed into an injection molding machine (with processing temperature of 190 C.) to obtain plastic samples. The characterization results are summarized in Table 2. Alumina nanoparticles helped to minimize the reduction of heat deflection temperature (HDT) by counteracting the influence of addition of polyolefin elastomer.

(34) TABLE-US-00002 TABLE 2 Izod % reduction % reduction Impact of E. coli of S. aureus Transparency Haze Strength HDT Yellowness Protein adsorption adsorption Sample (%) (%) (KJ/m.sup.2) ( C.) Index repellency (%) (%) PPR 84.1 26.4 7.21 78.1 10.6 No (Control) PPR-M 82.5 28.2 15.42 77.6 11.9 Yes >99% >99%

Example 3

(35) The modification of PPM, an impact-modified polypropylene compound, was rendered by extrusive compounding of PPM resin with 2% JEFFAMINE D-230, 2% AEO-5, 1% MILLAD NX8000, 0.1% dicumyl peroxide and 0.05% triallyl isocyanurate with processing temperature ranging from 170 C. to 190 C. to obtain a functional masterbatch concentrate (herein, annotated as PPM-M) after pelletization. The masterbatch was dry blended at a ratio of 1:1.5 w:w PPM with 0.1% overall by weight of IRGANOX 1010 and 0.1% overall by weight of IRGAFOS 168 for injection molding with processing temperature of 190 C. FIG. 5A shows that the molded plate sample of PPM-M is essentially transparent; The characterization results are summarized in Table 3, and also in FIG. 5B and FIG. 5C. FIG. 5B shows that when BSA protein solution added on the molded plate sample made of PPM-M effectively repelled protein adsorption onto the surface. Solution of bovine serum albumin (BSA), a protein molecule, was dropped on the sample surface for five minutes prior to aspiration. The Bradford Reagent (Coomassie Blue), which could react with the nitrogen of the BSA, was then dropped on the sample surface. The sample surface where BSA was adsorbed on would change Bradford Reagent from brown into blue color, indicating the adsorption of protein on the surface. Those surfaces repelled protein adsorption would keep Bradford reagent brown, indicating the protein repellency of sample surface. FIG. 5C shows that E. coli and S. aureus are substantially repelled (>99%) by the molded plate sample made of PPM-M. PPM-M passed ISO 22196 by showing a nearly log-4 reduction of bacterial counts after intimate contact with corresponding molded plate samples with accredited report certificate. PPM-M also passed ASTM G21 and ASTM G22 by indicating zero-growth ratings consistently over 21 days with accredited report certificate. Besides, PPM-M showed zero rating meaning a complete resistance against the pink staining by Streptoverticillium reticulum with accredited report certificate. Under ASTM E2149, a dynamic shake flask antibacterial test, PPM-M molded plates showed 100% and 90.7% reduction of E. coli and S. aureus respectively upon 24 hours of incubation with accredited report certificate. Under ISO 20645, an agar diffusion plate test, nil growth of E. coli, S. aureus, Salmonella typhimurium, Campylobacter jejuni under samples were observed while zero zone of inhibition were obtained with accredited test certificate, thus implicative of no free biocide leaching. The samples were antibacterial towards Klebsiella pneumoniae by showing 72% reduction of counts after 24 hours of contact even with agar slurries under ASTM E2180 with accredited report certificate. Furthermore, the total aerobic microbial count and the total combined molds and yeasts of the PPM-M pellets were less than 10 CFU/g according to USP <61> enumeration tests with accredited report certificate. The samples also complied with the overall migration limits for the three types of stimulants used (3% w/v acetic acid, 10% v/v ethanolic solution and rectified olive oil) at 70 C. for 2 hours as well as the two types of stimulants (3% w/v acetic acid, 10% v/v ethanolic solution) at 100 C. for 4 hours, as set out by EU No. 10/2011 as well as conformed to US FDA 21 CFR 177.1520(d), Items 3.1a and 3.2a as a polypropylene copolymer for intended uses in food contact articles. Relevant certificates issued from accredited agency were available. Furthermore, the total aerobic microbial count and the total combined molds and yeasts of the PPM-M pellets were less than 10 CFU/g according to USP <61> enumeration tests with accredited report certificate. The samples were also proven to be biocompatible under ISO 10993-4 (both direct contact and extract method) hemolysis tests and ISO 10993-5 (MEM elution method) cytotoxicity tests with accredited report certificates. Last but not least, an even slight increase of the impact strength of the base PPM plastic after modification was resulted.

(36) TABLE-US-00003 TABLE 3 Izod % reduction % reduction Impact Repellency of E. coli of S. aureus Transparency Haze Strength HDT towards adsorption adsorption Sample (%) (%) (KJ/m.sup.2) ( C.) Protein (%) (%) PPM 81.9 23.7 44.55 71.8 No NA NA (Control) PPM-M 82.6 20.3 47.46 73.1 Yes >99% >99%

Example 4

(37) The modification of PPH, a transparent polypropylene homopolymer, was rendered by extrusive compounding of PPH resins with 30% VISTAMAXX 3980FL, 2% JEFFAMINE D-230, 2% poly(ethylene glycol) sorbitol hexaoleate, 0.1% dicumyl peroxide, 0.05% triallyl isocyanurate and 3.75% alumina nanoparticles with processing temperature ranging from 180 C. to 200 C. The reformulated pellets were then directly subjected to injection molding (with processing temperature of 200 C.) to get molded samples. The characterization results are summarized in the table below. The impact strength increased significantly by more than 120% with respect to the base PPH plastic. Alumina nanoparticles were added to keep the heat deflection temperature (HDT) of PPH as high as about 80 C. for warm water contacting applications. Characterization results are summarized in Table 4.

(38) TABLE-US-00004 TABLE 4 Izod % reduction % reduction Impact Repellency of E. coli of S. aureus Yellowness Transparency Haze Strength HDT towards adsorption adsorption Sample Index (%) (%) (KJ/m.sup.2) ( C.) Protein (%) (%) PPH 10.06 83.9 17.0 4.49 98.9 No NA NA (Control) PPH-M 15.83 81.6 29.5 9.94 79.2 Yes >99% >99%

Example 5

(39) The modification of SEBS, a styrene ethylene butylene styrene block thermoplastic elastomer, was rendered by extrusive compounding of SEBS resins with 0.1% tosylic acid, 2.5% polyethylene glycol (average molecular weight of 10,000) and 2.5% AEO-5 on a weight basis with processing temperature ranging from 170 C. to 220 C. The reformulated pellets were directly subjected to injection molding (with a processing temperature of 210 C.) to obtain molded samples. Characterization results are summarized in Table 5

(40) TABLE-US-00005 TABLE 5 % reduction % reduction Elongation Repellency of E. coli of S. aureus Yellowness Transparency Haze at break towards adsorption adsorption Sample Index (%) (%) (%) Protein (%) (%) SEBS 8.12 82.5 20.2 420% No NA NA (Control) SEBS-M 10.03 79.2 26.4 400% Yes >99% >98%