Deacetylation behavior of binary blend films of cellulose acetate and various polymers

For binary blend films of cellulose acetate (CA) and various polymers, the elution behavior of the polymers from the CA films in different environments (i.e., soil, water) was examined. For the CA film containing poly(ethylene glycol) (PEG), the PEG eluted to the periphery of the film completely. On the other hand, polyvinylpyrrolidone blended with CA remained in the CA film. A CA film containing acrylic acid was prepared, and this film was heated. The elution of acrylic acid was inhibited by its polymerization. These results suggested that the internal polymers were capable of remaining in the CA film by polymer entanglement. Second, we examined the deacetylation and biodegradation behavior of CA films containing polymers with a phosphoric acid moiety in the side chain, such as poly(2‐hydroxyethyl methacrylate phosphoric acid ester) [poly(HEMA‐P)]. Poly(HEMA‐P) had the ability to deacetylate the CA, and the biodegradation rate of the CA films containing poly(HEMA‐P) increased in comparison with that of the nonadditive CA films. The elution of internal 2‐hydroxyethyl methacrylate phosphoric acid ester was inhibited by the copolymerization with 2‐hydroxyethyl methacrylate or crosslinking. In the case of both 2‐hydroxyethyl methacrylate phenyl phosphoric acid ester and 10‐methacryloyloxydecyl dihydrogen phosphate, the acetone‐soluble polymers were obtained by radical polymerization in a mixture of acetone and water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1816–1823, 2006     

抗消化乙酰酯淀粉结构和结肠靶向性能研究

采用扫描电镜、X射线衍射和生物体外(In-V itro)降解等方法,对不同取代度DS的抗消化乙酰酯淀粉的颗粒形貌、结晶结构和生物降解性能进行了研究。结果表明:乙酰酯淀粉的颗粒表面变得粗糙并发生破损;随着乙酰基团取代度的增大,淀粉的抗消化性能不断提高,当DS>2时,淀粉中抗消化淀粉质量分数达到90%以上,其结晶结构也由A型向V型转变。生物体外降解试验表明,抗消化乙酰酯淀粉薄膜在模拟人体上消化道环境中的降解程度低于2.5%,在人工模拟结肠环境中的微生物降解程度为30%—50%,显示出潜在的结肠靶向性和微生物降解性。由此可见,抗消化乙酰酯淀粉适合作为菌群触发型口服结肠靶向药物控释载体材料。     

Polyester biocomposites from recycled natural fibers: Characterization and biodegradability

The structure, biodegradability, and morphological properties of composite materials composed of poly(butylene succinate adipate) (PBSA) and bamboo fiber (BF) were evaluated. Composites containing acrylic acid‐grafted PBSA (PBSA‐g‐AA/BF) exhibited noticeably enhanced compatibility between the two components. The dispersion of BF in the PBSA‐g‐AA matrix was highly homogeneous as a result of ester formation and the consequent creation of branched and crosslinked macromolecules between the carboxyl groups of PBSA‐g‐AA and hydroxyl groups in BF. In addition, the PBSA‐g‐AA/BF composite was more easily processed due to a lower melt viscosity. Each composite was subjected to biodegradation tests in an Acinetobacter baumannii compost. Morphological observations indicated severe disruption of film structure after 10–20 days of incubation, and both the PBSA and the PBSA‐g‐AA/BF composite films were eventually completely degraded. The PBSA‐g‐AA/BF films were more biodegradable than those made of PBSA and exhibited a lower molecular weight and intrinsic viscosity, implying a strong connection between these characteristics and biodegradability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of propylation of starch with different degrees of substitution on the properties and characteristics of starch‐low density polyethylene blend films

Corn starch was modified by propylation and degree of substitution (DS) of four starch modifications were 0.61, 1.56, 2.27, and 2.51. Different films were prepared by blending native and propylated starch with low‐density polyethylene (LDPE). The mechanical properties, thermal properties, water absorption capacity, and biodegradability of the blend films varied with the quantity of starch as well as DS. Tensile strength, elongation, and melt flow index of propylated starch blend films were higher compared to the corresponding native starch blend film. These properties improved with increase in DS from 1.56 to 2.51. Propylated starch blend films were found thermally stable than native starch blend films. There was a decrease in water absorption capacity for the films containing propylated starch at high DS. Enzymatic and soil burial degradation results showed that biodegradability of starch‐LDPE films increased with the increase in the starch concentration but it decreased with increase in the DS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Performance and biodegradability of a maleated polyester bioplastic/recycled sugarcane bagasse system

The biodegradability, morphology, and mechanical properties of composite materials made of poly(butylene succinate adipate) (PBSA) and sugarcane bagasse (SCB) were evaluated. Composites containing maleic anhydride (MA)‐grafted PBSA (PBSA‐g‐MA/SCB) exhibited noticeably superior mechanical properties because of greater compatibility between the two components. The dispersion of SCB in the PBSA‐g‐MA matrix was highly homogeneous as a result of ester formation between the carboxyl groups of PBSA‐g‐MA and hydroxyl groups in SCB and the consequent creation of branched and crosslinked macromolecules. Each composite was subjected to biodegradation tests in a Rhizopus oryzae compost. Morphological observations indicated severe disruption of film structure after 60 days of incubation, and both the PBSA and the PBSA‐g‐MA/SCB composite films were eventually completely degraded. The PBSA‐g‐MA/SCB films were more biodegradable than those made of PBSA and exhibited a higher intrinsic viscosity, implying a strong connection between these characteristics and biodegradability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation,characterization, and biodegradability of renewable resource‐based composites from recycled polylactide bioplastic and sisal fibers

The biodegradability, morphology, and mechanical thermal properties of composite materials composed of polylactide (PLA) and sisal fibers (SFs) were evaluated. Composites containing acrylic acid‐grafted PLA (PLA‐g‐AA/SF) exhibited noticeably superior mechanical properties because of greater compatibility between the two components. The dispersion of SF in the PLA‐g‐AA matrix was highly homogeneous as a result of ester formation and the consequent creation of branched and crosslinked macromolecules between the carboxyl groups of PLA‐g‐AA and hydroxyl groups in SF. Furthermore, with a lower melt temperature, the PLA‐g‐AA/SF composite is more readily processed than PLA/SF. Both composites were buried in soil to assess biodegradability. Both the PLA and the PLA‐g‐AA/SF composite films were eventually completely degraded, and severe disruption of film structure was observed after 6–10 weeks of incubation. Although the degree of weight loss after burial indicated that both materials were biodegradable even with high levels of SF, the higher water resistance of PLA‐g‐AA/SF films indicates that they were more biodegradable than those made of PLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Heterogeneous method of chitosan film preparation: Effect of multifunctional acid on film properties

The heterogeneous crosslinking method was applied to chitosan films with citric acid to observe and understand the effect of a multifunctional acid at a low concentration on film properties. Neat and neutralized chitosan films and films containing 15% (w/w) citric acid (denoted as CA films) were characterized by mechanical, water vapor permeability (WVP), and thermogravimetric analysis tests. The CA films displayed a higher tensile strength by 10%, lower WVP by 30%, and higher thermal stability, compared to neutralized films. The crystalline structure converted back from tendon to Type II after the addition of citric acid, as determined by X-ray diffraction. Neat films displayed a lower water contact angle (72°) compared to neutralized and CA films (78°–79°). The heterogeneous method was also applied to incorporate a plasticizer into a neutralized film to potentially observe the glass transition using dynamic mechanical analysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48648.     

Polyester/natural fiber biocomposites: preparation,characterization, and biodegradability

In this study, the biodegradability, morphology, mechanical, and thermal properties of composite materials composed of polybutyleneterephthalate (PBT), acrylic acid-grafted PBT (PBT-g-AA), and sisal fibers (SFs) were evaluated. Composites containing acrylic acid-grafted PBT (PBT-g-AA/SF) exhibited superior mechanical properties because of their greater compatibility with SF than PBT/SF. The dispersion of SF in the PBT-g-AA matrix was highly homogeneous due to ester formation and the creation of branched and cross-linked macromolecules between the carboxyl groups of PBT-g-AA and the hydroxyl groups of SF. Furthermore, due to its lower melting temperature (T _m), the PBT-g-AA/SF composite was more readily synthesized. Each composite was subjected to biodegradation tests in a soil environment. Both the PBT and PBT-g-AA/SF composite films were completely degraded, with severe disruption of the film structures observed after 60–100 days of incubation. Although the degree of weight loss following burial indicated that both materials were biodegradable, even with high levels of SF loading, the higher water resistance of PBT-g-AA/SF films indicated their higher biodegradability than the PBT films.     

Control of biodegradability of poly(3‐hydroxybutyric acid) film with grafting acrylic acid and thermal remolding

Radiation‐induced graft polymerization of acrylic acid (AAc) on poly(3‐hydroxybutyric acid) (PHB) film was carried out and the resulting film was thermally‐remolded. The PHB films grafted with AAc (PHB‐g‐AAc) having a degree of grafting higher than 5% completely lost the enzymatic degradability. The enzymatic degradability of the grafted film was recovered by thermal remolding. The highest enzymatic degradation rate was observed at degree of grafting of 10% after thermal remolding. The PHB‐g‐AAc films and thermally‐remolded PHB‐g‐AAc films were characterized by contact angle and differential scanning calorimetry. The enzymatic degradability of PHB‐g‐AAc films was lost by the grafted AAc, which covered the surface of PHB film. The acceleration of enzymatic degradation in the remolded PHB‐g‐AAc films was mainly caused by decrease of crystallinity of PHB by dispread of grafted AAc during thermal remolding. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3856–3861, 2006     

Aerobic biodegradation of cellulose acetate

Two separate assay systems were used to evaluate the biodegradation potential of cellulose acetate: an in vitro enrichment cultivation technique (closed batch system), and a system in which cellulose diacetate (CDA) films were suspended in a wastewater treatment system (open continuous feed system). The in vitro assay employed a stable enrichment culture, which was initiated by inoculating a basal salts medium containing cellulose acetate with 5% (v/v) activated sludge. Microscopic examination revealed extensive degradation of CDA (DS = 2.5) fibers after 2–3 weeks of incubation. Characterization of the CA fibers recovered from inoculated flasks demonstrated a lower average degree of substitution and a change in the mol wt profiles. In vitro enrichments with CDA (DS = 1.7) films were able to degrade > 80% of the films in 4–5 days. Cellulose acetate (DS = 2.5) films required 10–12 days for extensive degradation. Films prepared from cellulose triacetate remained essentially unchanged after 28 days in the in vitro assay. The wastewater treatment assay was less active than the in vitro enrichment system. For example, approximately 27 days were required for 70% degradation of CDA (DS = 1.7) films to occur while CDA (DS = 2.5) films required approximately 10 weeks before significant degradation was obtained. Supporting evidence for the biodegradation potential of cellulose acetate was obtained through the conversion of cellulose [1-¹⁴C]-acetate to ¹⁴CO₂ in the in vitro assay. The results of this work demonstrate that cellulose acetate fibers and films are potentially biodegradable and that the rate of biodegradation is highly dependent on the degree of substitution. © 1993 John Wiley & Sons, Inc.     

Preparation of artificial wood films with controlled biodegradability

Artificial wood films containing cellulose, xylan, and lignin were easily prepared by the dissolution of wood components in 1‐ethyl‐3‐methylimidazolium acetate followed by reconstitution with distilled water. The composition and characteristics of wood films were highly controllable and predictable through the variation of the concentration of each component in the wood solution. The water vapor solubility of the wood films was increased when the xylan content was increased and the content of lignin was decreased. The biodegradability of the artificial wood films was investigated with cellulase from Trichoderma viride. The relative degradability of the wood film prepared with 5% cellulose and 5% lignin was 42%, whereas that of the wood film made with 5% cellulose and 5% xylan was 189%. The biodegradability of cellulose in the wood films correlated well with the content of xylan and lignin, and it was enhanced when the xylan content was increased and the content of lignin was decreased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42109.     

Effect of amylose contents of starches on physical properties and biodegradability of starch/PVA-blended films

Recently, synthetic plastics are used widely in various fields, and with increased applications, disposal of waste plastics has become a serious problem. Therefore, development of novel plastics that are degradable by microorganisms in soil has recently been attracting much attention. In this study, starch/PVA-blended films were prepared from commercial starches with the different amylose contents, PVA, and additives by using a simple mixing process and casting method. Glycerol (GL), sorbitol (SO), tartaric acid (TA), and citric acid (CA) were used as additives. The physical properties such as tensile strength (TS), elongation at break (%E), degree of swelling (DS), and solubility (S) with amylose contents of starches were investigated. The amylose content of starches was analyzed by the colorimetric method. Thermal analysis of films was measured by using a differential scanning calorimeter (DSC). Finally, biodegradability of the films was evaluated in a 6-month soil burial test. The examination of the physical properties of biodegradable films indicates that with the higher amylose contents of starch used in preparing the film, TS, and DS of films increased, whereas %E and S decreased. The additives containing both carboxyl and hydroxyl groups, i.e. TA and CA, improved the physical properties of films. A thermal analysis of films revealed that the glass transition temperature (T _g) rose because of the increased crystallization of films with the increasing the amylose contents. Also, films degraded rapidly at the beginning and slow degradation took place until the experiment was completed. The films showed 50–80% degradation.     

Bone cell viability on methacrylic acid grafted and collagen immobilized porous poly(3‐hydroxybutrate‐co‐3‐hydroxyvalerate)

Porous poly(3‐hydroxybutrate‐co‐3‐hydroxyvalerate) (PHBV) film was prepared by solute leaching of salt/PHBV cast film. The surface chemistry of the PHBV membrane was modified by performing graft polymerization of methacrylic acid (MAA) on ozone treated porous PHBV film, followed by immobilization of type I collagen. The surface characteristics of the modified and nonmodified porous films were measured by water contact angle. The rat osteosarcoma cell line UMR‐106 osteoblast like cells were used as model cells to evaluate the cell viability on surfaces. The initial cell attachment, growth pattern, and proliferation as measured by MTT assay were used to evaluate the bone cell viability on the modified and nonmodified films. Among the PHBV films studied, the nonmodified porous PHBV and the porous PHBV film type I collagen dip coated showed no significant difference in cell attachment and proliferation, while the porous PHBV membrane that was collagen immobilized after MAA grafting showed considerable activity of osteoblast like cells. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1916–1921, 2005     

New methods for acylation of pure and sawdust‐extracted cellulose by fatty acid derivatives—Thermal and mechanical analyses of cellulose‐based plastic films

This work deals with the synthesis of cellulosic plastic films obtained in homogeneous conditions by microwave‐induced acylation of commercial or chestnut tree sawdust cellulose by fatty acids. The acylation reaction was studied according to N,N‐dimethyl‐4‐aminopyridine (DMAP) amount, DMAP simultaneously playing the role of catalyst and proton trapping base. This study clearly showed that DMAP does not influence degrees of substitution (DS), massic, and molar yields. Plastic films synthesized in the absence of DMAP showed a decrease in mechanical behavior. Organic (tributylamine) or inorganic bases (CaCO₃, Na₂CO₃) were then added to replace DMAP basic activity, and no changes were observed. Concerning thermal and mechanical properties of plastics obtained with various bases, glass transition temperatures (T_g) and degradation temperature (T_d) were found constant whatever the base, and the best mechanical properties were obtained for films synthesized in the presence of CaCO₃. The same remarks were made concerning the valorization of chestnut tree sawdust cellulose. Microbial biodegradation of plastic films with DS = 2.2 led to a loss of their mechanical behaviors. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1266–1278, 2005     

Biodegradation of polyhydroxybutyrate and hollow glass microspheres composite films

Biodegradable polymers represent an alternative to the conventional ones. The polyhydroxybutyrate (PHB) is one of the most used biodegradable polymers. However, PHB presents narrow processing window, which limits its applicability. The development of PHB composites offers a solution for that drawback. In this work, PHB and hollow glass microspheres (HGMs) composite films are developed. Subsequently, the films are characterized, and the biodegradability of the films is determined by the Sturm test. A suitable distribution and intermediate dispersion of the filler throughout the matrix are observed, while adhesion between the components is not achieved. The HGM does not significantly affect the thermal properties of the systems, however, decreases the degree of crystallinity. In addition, the composite films present small values of elongation and tensile strength than the pure PHB film. Finally, the HGM modified the mechanism of biodegradation; however, there was no change in the rate of biodegradation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47195.     

Preparation and biodegradation of hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol) and its segmented polyurethane

Hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol), poly(FA‐co‐DEG) was prepared by melt polycondensation. The resultant unsaturated aliphatic polyester was characterized by Fourier transform infrared (FTIR) spectroscopy, hydroxyl value, acid value, and intrinsic viscosity. Its enzymatic degradation and crosslinking behavior as well as the effect of crosslinking degree on enzymatic degradation were also investigated. The crosslinking degree and reduction of carbon–carbon double bonds revealed excellent self‐crosslinking nature of poly(FA‐co‐DEG) at high temperature. The results of enzymatic degradation showed that poly(FA‐co‐DEG) has excellent biodegradability and that the biodegradation can be controlled by the crosslinking degree. Polyurethane was prepared by the reaction of poly(FA‐co‐DEG), 2,4‐toluene diisocyanate (TDI), and 1,4‐butanediol (BD). It was found that the biodegradation of the obtained polyurethane was slower than that of the original unsaturated aliphatic polyester poly(FA‐co‐DEG). The peeling strength of the polyurethane was very high, supporting better adhesion property with enhanced crosslinking. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Deterioration behavior of cellulose acetate films in acidic or basic aqueous solutions

The deterioration behavior of cellulose acetate (CA) films (degree of substitution = 2.5) was examined in hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions of various concentrations to determine acid and base catalytic effects in heterogeneous systems at room temperature. With concentrations of 0.5N HCl and 0.01N NaOH and higher, the physical properties of the films changed. The films, recovered after 1–10 days of immersion, were slightly opaque and rubbery from swelling in the solutions before drying. They became brittle and shrank when they dried. For HCl immersion, the weight change of a film depended on the HCl concentration and the immersion time. With 6.0N HCl, the film shape was broken, and a fine powder was deposited in the solution with a recovery of 53.8 wt %. The infrared spectrum of this deposit indicated that it was completely deacetylated cellulose. For NaOH immersion, although the weight change depended on the NaOH concentration, the weight loss reached 40–50% within the first 24 h, and it was constant with respect to the immersion time and base concentration in 0.5N NaOH or NaOH of a higher concentration. The infrared and gel permeation chromatography analyses showed that this deterioration mainly depended on the deacetylation of CA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3354–3361, 2004     

Compatibilization of starch/poly(butylene adipate‐co‐terephthalate) blown films using itaconic acid and sodium hypophosphite

Itaconic acid (IA) has potential as a compatibilizing agent in polymeric blends due to its unique chemical characteristics. Sodium hypophosphite (SHP) has been studied as a catalyst in esterifying reactions using multicarboxylic acids. Starch/poly(butylene adipate‐co‐terephthalate) blown films containing IA, with and without SHP, were produced. The film containing IA presented higher tensile strength (8.166 MPa) and elongation (891.473%) than the control film (5.548 MPa and 487.637%, respectively). When SHP was added (sample IA‐SHP), tensile strength increased even more (9.215 MPa); however, elongation (636.821%) was lower than in the IA film. This behavior was attributed to crosslinking between two starch itaconoate molecules intermediated by SHP. The increase in the compatibility between the polymeric phases justified the lower permeability to water vapor of the IA‐SHP films and was responsible for the production of films with a more compact and homogeneous structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46629.     

PLA在受控堆肥条件下的生物降解行为研究

依据ISO 14855的检测方法,研究了聚乳酸(PLA)在受控堆肥条件下的生物降解性能,结果表明:PLA具有良好的生物降解性。在培养土提取液中,以蛋白酶K对PLA膜进行降解,显微镜观察发现,PLA膜表面逐渐被蛋白酶侵蚀;红外光谱研究表明,PLA膜在降解前后的分子结构没有发生很大变化。     

羧甲基取代度对淀粉生物降解性能的影响

利用半生物体内模型和扫描电子显微技术系统地研究了取代度在0 05至0 40的羧甲基淀粉的生物降解性能,并用微生物降解代谢过程中CO2的净生成速度和剩余淀粉质量分数对羧甲基淀粉的生物降解速度和降解程度进行了表征。结果表明,淀粉经羧甲基化后,有利于微生物分泌的淀粉酶对淀粉分子链的水解。但随着羧甲基取代度的提高,水解产物中的羧甲基基团的质量分数增大,淀粉的生物降解速度和程度先增大后减少,说明羧甲基低聚糖不利于被微生物完全代谢。当取代度≤0 10时,羧甲基化促进玉米淀粉的生物降解速度和程度;当取代度为0 40时,羧甲基化抑制淀粉的生物降解,30d后其生物降解速度和程度分别为9 82mg·g-1·d-1和67 1%。淀粉的生物降解性能可以通过调节羧甲基取代度的大小来控制。