Preparation and characterization of microbial biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/organoclay nanocomposites

Novel biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐co‐4HB)]/organoclay nanocomposites were prepared via solution casting. Exfoliated nanocomposite structure was confirmed by wide‐angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM) for the nanocomposites with low organoclay loadings (≤3 wt%), whereas the mixtures of exfoliated and unexfoliated organoclays were appeared in the nanocomposite with an organoclay content of 5 wt%. The organoclay fillers accelerated significantly the cold crystallization process of P(3HB‐co‐4HB) matrix. The thermal stability of the nanocomposites was in general better than that of pristine P(3HB‐co‐4HB). Considerable increase in tensile modulus was observed for the nanocomposites, especially at an organoclay content of 3 wt%. These results demonstrated that the nanocomposites improved the material properties of P(3HB‐co‐4HB). POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Mechanical properties,thermal stability,and crystallization kinetics of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/calcium carbonate composites

Bacterial polyester poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB) containing 5 mol% 4HB was composited with different calcium carbonate (CaCO₃) fillers. The effect of CaCO₃ contents on thermal properties, mechanical property, and crystallization kinetics was evaluated. The thermal stability of P3/4HB was reduced by mixing with CaCO₃ particles. With increasing CaCO₃ content, the elongation at break, tensile strength, and impact strength decrease; however, elastic modulus increases. When P3/4HB with 20 mol% 4HB was added into the P3/4HB/CaCO₃ composite, the impact strength were enhanced significantly; however, the elongation at break and tensile strength were only slight to moderate improvements. However, when compared with nano‐ and light‐CaCO₃, heavy CaCO₃ had the best mechanical properties. The nonisothermal and isothermal crystallization results demonstrated that the crystallization rate of P3/4HB was reduced and the highest crystallinity was obtained for all kinds of CaCO₃ fillers at 40 phr content. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Study on the poly(3‐hydroxybutyrate‐co−4‐hydroxybutyrate)‐based composites toughened by synthesized polyester polyurethane elastomer

In this study, polycaprolactone(PCL)‐based polyurethane (PU) elastomer containing 45 wt % hard segment component was synthesized and characterized by fourier transform infrared spectroscopy, gel permeation chromatography, and X‐ray diffraction. As a toughening agent, the as‐synthesized PU was incorporated into biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3,4)HB] by solution casting to prepare P(3,4)HB/PU composites. The microstructure and properties of P(3,4)HB/PU composites were investigated using transmission electron microscopy, X‐ray diffraction, tensile testing, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and activated sludge degradation testing. The results show that PU can disperse well in a P(3,4)HB matrix. The elongation at break of P(3,4)HB/PU composites is remarkably increased while the yield strength and elastic modulus are decreased with an increase in PU content. At the same time, it is found that the fracture characteristic of P(3,4)HB is obviously transformed from brittleness into ductility with a gradual increase in PU loading. Moreover, the thermal stability of P(3,4)HB/PU composites is significantly improved compared with that of pure P(3,4)HB. In addition, the biodegradation rate of P(3,4)HB/PU composites is evidently reduced with the increase of PU content in the activated sludge degradation testing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42740.     

Morphology and properties of biodegradable and biosourced polylactide blends with poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)

Biodegradable polymer blends based on biosourced polymers, namely polylactide (PLA) and poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P(3HB‐co‐4HB)), were prepared by melt compounding. The effects of P(3HB‐co‐4HB) on the miscibility, phase morphology, thermal behavior, mechanical properties, and biodegradability of PLA/P(3HB‐co‐4HB) blends were investigated. The blend was an immiscible system with the P(3HB‐co‐4HB) domains evenly dispersed in the PLA matrix. However, the T_g of P(3HB‐co‐4HB) component in the blends decreased compared with neat P(3HB‐co‐4HB), which might be attributed to that the presence of the phase interface between PLA and P(3HB‐co‐4HB) resulted in enhanced chain mobility near interface. The addition of P(3HB‐co‐4HB) enhanced the cold crystallization of PLA in the blends due to the nucleation enhancement of PLA caused by the enhanced chain mobility near the phase interface between PLA and P(3HB‐co‐4HB) in the immiscible blends. With the increase in P(3HB‐co‐4HB) content, the blends showed decreased tensile strength and modulus; however, the elongation at beak was increased significantly, indicating that the inherent brittlement of PLA was improved by adding P(3HB‐co‐4HB). The interesting aspect was that the biodegradability of PLA is significantly enhanced after blends preparation. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Preparation and characterization of biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/silica nanocomposites

Biodegradable poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐co‐4HB)]/silica nanocomposites were prepared by melt compounding. The effects of silica on the morphology, crystallization, thermal stability, mechanical properties, and biodegradability of P(3HB‐co‐4HB) were investigated. The nanoparticles showed a fine and homogeneous dispersion in the P(3HB‐co‐4HB) matrix for silica contents below 5 wt%, whereas some aggregates were detected with further increasing silica content. The addition of silica enhanced the crystallization of P(3HB‐co‐4HB) in the nanocomposites due to the heterogeneous nucleation effect of silica. However, the crystal structure of P(3HB‐co‐4HB) was not modified in the presence of silica. The thermal stability of P(3HB‐co‐4HB) was enhanced by the incorporation of silica. Silica was an effective reinforcing agent for P(3HB‐co‐4HB), and the modulus and tensile strength of the nanocomposites increased, whereas the elongation at break decreased with increasing silica loading. The exciting aspect of this work was that the rate of enzymatic degradation of P(3HB‐co‐4HB) was enhanced significantly after nanocomposites preparation. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Miscibility and crystallization behaviors of poly(3‐hydroxybutyrate‐co‐11%‐4‐hydroxybutyrate)/Poly(3‐hydroxybutyrate‐co‐33%‐4‐hydroxybutyrate) blends

Biopolyesters poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) with an 11 mol % 4HB content [P(3HB‐co‐11%‐4HB)] and a 33 mol % 4HB content [P(3HB‐co‐33%‐4HB)] were blended by a solvent‐casting method. The thermal properties were investigated with differential scanning calorimetry. The single glass‐transition temperature of the blends revealed that the two components were miscible when the content of P(3HB‐co‐33%‐4HB) was less than 30% or more than 70 wt %. The blends, however, were immiscible when the P(3HB‐co‐33%‐4HB) content was between 30 and 70%. The miscibility of the blends was also confirmed by scanning electron microscopy morphology observation. In the crystallite structure study, X‐ray diffraction patterns demonstrated that the crystallites of the blends were mainly from poly(3‐hydroxybutyrate) units. With the addition of P(3HB‐co‐33%‐4HB), larger crystallites with lower crystallization degrees were induced. Isothermal crystallization was used to analyze the melting crystallization kinetics. The Avrami exponent was kept around 2; this indicated that the crystallization mode was not affected by the blending. The equilibrium melting temperature decreased from 144 to 140°C for the 80/20 and 70/30 blends P(3HB‐co‐11%‐4HB)/P(3HB‐co‐33%‐4HB). This hinted that the crystallization tendency decreased with a higher P(3HB‐co‐33%‐4HB) content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The influence of 4HB content on the properties of poly(3‐hydroxylbutyrate‐co‐4‐hydroxylbutyrate) based on melt molded sheets

A series of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)s[P(3HB‐co‐4HB)s] sheets with the 4HB contents from about 9 to 34 mol % were prepared via melt molding. Their crystallinity, crystalline structures, thermal and mechanical properties were characterized by differential scanning calorimetry, X‐ray diffraction, thermogravimetric analysis, dynamic mechanical analysis, and tensile test. It was found that the melt temperatures (T_m), glass transition temperatures (T_g), and storage modulus (E′) of all the [P(3HB‐co‐4HB)s] copolymers investigated decreased continuously with increasing the amount of the 4HB; the yield stress and breaking stress nearly decreased with the increase of the 4HB contents while the elongation at the yield and break points increased; and the thermal stability of the P(3HB‐co‐4HB)s improved with increasing 4HB contents. The results suggest that the mechanical properties and crystal lattice parameters of the melt molded sheets are somewhat different from those of the solution cast films. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Miscibility,crystallization kinetics,and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)(PHBV)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)(P3/4HB) blends

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)(PHBV)/poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB) blend films were prepared by solvent‐cast method. The nonisothermal crystallization results showed that PHBV and P3/4HB are miscible due to a single glass transition temperature (T_g), which is dependent on blend composition. The isothermal crystallization results demonstrate that the crystallization rate of PHBV becomes slower after adding amorphous P3/4HB with 19.2 mol% 4HB, which could be proved through depression of equilibrium melt point ($T_m^o$ ) from 183.7°C to 177.6°C. For pure PHBV and PHBV/P3/4HB (80/20) blend, the maximum crystallization rate appeared at 88°C and 84°C, respectively. FTIR analysis showed that PHBV/P3/4HB blend films would maintain the helical structure, similar to pure PHBV. Meanwhile, with increasing P3/4HB content, the inter‐ and intra‐interactions of PHBV and P3/4HB decrease gradually. Besides, a lower elastic modulus and a higher elongation at break were obtained, which show that the addition of P3/4HB would make the brittle PHBV to ductile materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study of miscibility,crystallization, mechanical properties,and thermal stability of blends of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)

Natural amorphous polymer poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3HB4HB) containing 41 mol % of 4HB was blended with poly(3‐hydroxybutyrate) (PHB) with an aim to improve the properties of PHB. The influence of P3HB4HB contents on thermal and mechanical properties of the blends was evaluated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, stress–strain measurement and thermo gravimetric analyzer. Miscibility of PHB/P3HB4HB blends was mainly decided by the contents of P3HB4HB. When P3HB4HB exceeded 50 wt %, the two polymer phases separated and showed immiscibility. The addition of P3HB4HB did not alter the crystallinity of PHB, yet it diluted the PHB crystalline phase as revealed by DSC studies. DSC and FTIR results showed that the overall crystallinity of the blends decreased remarkably with increasing of P3HB4HB contents. Decreased glass transition temperature and crystallinity imparted desired flexibility for the blends. The ductility of the blends increased progressively with increasing of P3HB4HB content. Thus, the PHB mechanical properties can be modulated by changing the blend composition. P3HB4HB did not significantly improve the thermal stability of PHB, yet it is possible to melt process PHB without much molecular weights loss via blending it with suitable amounts of P3HB4HB. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Biodegradation of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) by a novel P3/4HB depolymerase purified from Agrobacterium sp. DSGZ

A poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB)‐degrading strain, Agrobacterium sp. DSGZ, was isolated from sewage by poly(3‐hydroxybutyrate) (PHB) mineral agar plates. A novel P3/4HB depolymerase with a molecular weight of 34 kDa was purified through a novel single‐step affinity chromatography method from the culture supernatant of the strain by using P3/4HB powder as a substrate. The purified depolymerase showed optimum activity at pH 7.0 and 50°C, and was stable at the pH range of 6.0 to 9.0 and temperature below 50°C. Enzyme activity was strongly inhibited by phenylmethylsulfonyl fluoride (PMSF), ethylenediaminetetraacetic acid (EDTA), hydrophobic reagents, and some metal ions. The depolymerase degraded poly(3‐hydroxybutyrate) (PHB), poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV), P3/4HB, and polycaprolactone (PCL), instead of polylactic acid (PLA) or poly(butylene succinate) (PBS). Meanwhile, the depolymerase showed high hydrolytic activity against short‐chain length esters, such as butyrate acid ester and caprylic acid ester. The main degradation products of the depolymerase were identified as hydroxybutyrate monomers and dimers, and the monomers were identified as 3‐hydroxybutyrate (3HB) monomers and 4‐hydroxybutyrate (4HB) monomers. The preparation procedure, crystallinity, and 4HB composition of the P3/4HB copolymer showed evident effect on degradation behavior, and change in crystallinity was the main factor affecting degradation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42805.     

Improvement of the production of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate‐co‐4‐hydroxybutyrate) terpolyester by manipulating the culture condition

BACKGROUND: The aim of this work is to enhance the production of terpolyester poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate‐co‐4‐hydroxybutyrate) (P(3HB‐co‐3HV‐co‐4HB)) produced by a locally isolated bacterium, Cupriavidus sp. USMAA2‐4. The monomer composition was varied by supplementing different carbon precursors and by manipulating the culture condition through one‐stage cultivation. The effect of C/N ratio and different concentrations of carbon source and precursors were investigated in order to produce higher content of this terpolyester. Although research on this biodegradable polyester is abundant, studies on terpolyester P(3HB‐co‐3HV‐co‐4HB) are still limited. RESULTS: Supplementation of oleic acid in accumulation medium increased the bacterial growth and polyhydroxyalkanoate (PHA) accumulation. It was also shown that medium consisting of assorted carbon precursors at C/N 20 gave relatively high dry cell weight and P(3HB‐co‐3HV‐co‐4HB) content. Various compositions of terpolyester were obtained when the concentration of oleic acid and 4HB precursors were manipulated. The combination of oleic acid with γ‐butyrolactone and 1‐pentanol was found to be the best combination to produce high PHA content (81 wt%). The composition of monomer in P(3HB‐co‐3HV‐co‐4HB) was produced in the range 8–13 mol% for 3HV and 9–24 mol% for 4HB, respectively. CONCLUSIONS: The production of P(3HB‐co‐3HV‐co‐4HB) in shake‐flasks successfully produced 81 wt% of PHA content. This manipulated culture condition can be used at larger scale to provide modeling for the production of terpolyester in a bioreactor. Copyright © 2012 Society of Chemical Industry     

Tailoring the surface architecture of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) scaffolds

This study was designed to determine whether the surface modifications of the various poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐co‐4HB)] copolymer scaffolds fabricated would enhance mouse fibroblast cells (L929) attachment and proliferation. The P(3HB‐co‐4HB) copolymer with a wide range of 4HB monomer composition (16–91 mol %) was synthesized by a local isolate Cupriavidus sp. USMAA1020 by employing the modified two‐stage cultivation and by varying the concentrations of 4HB precursors, namely γ‐butyrolactone and 1,4‐butanediol. Five different processing techniques were used in fabricating the P(3HB‐co‐4HB) copolymer scaffolds such as solvent casting, salt‐leaching, enzyme degradation, combining salt‐leaching with enzyme degradation, and electrospinning. The increase in 4HB composition lowered melting temperatures (T_m) but increased elongation to break. P(3HB‐co‐91 mol % 4HB) exhibited a melting point of 46°C and elongation to break of 380%. The atomic force analysis showed an increase in the average surface roughness as the 4HB monomer composition increased. The mouse fibroblasts (L929) cell attachment was found to increase with high 4HB monomer composition in copolymer scaffolds. These results illustrate the importance of a detailed characterization of surface architecture of scaffolds to provoke specific cellular responses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Morphology,mechanical property,and modeling evaluation of P(3HB‐co‐4HB)/nano‐ZnO composites

Poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P(3HB‐co‐4HB)) and nanometer zinc oxide (nano‐ZnO) modified by solid titanate coupling agent (TMC980) were selected to prepare P(3HB‐co‐4HB)/nano‐ZnO composites via melt blending. Scanning electron microscope (SEM), capillary rheometer, polarized optical microscopy (POM), and universal testing machine were used to characterize the fracture morphology, rheological property, spherulitic morphology, and mechanical properties of P(3HB‐co‐4HB)/nano‐ZnO composites. Halpin‐Tsai equation was used to quantitatively evaluate the dispersion and enhancement effects of modified nano‐ZnO on P(3HB‐co‐4HB). The results demonstrated that modified nano‐ZnO at 0.2%∼0.3% of volume fraction could significantly improve the tensile strength, elastic modulus and toughness, increase the melt viscosity, refine the spherulitic size, and rough the fracture morphology of P(3HB‐co‐4HB)/nano‐ZnO composites. Based on the effective aspect ratio (ξ) from Halpin‐Tsai model evaluation, the optimal dosage of nano‐ZnO for P(3HB‐co‐4HB)/nano‐ZnO composites was also at 0.2%∼0.3% of volume fraction. The Halpin‐Tsai equation was found to predict the experimental data most accurately for the P(3HB‐co‐4HB)/nano‐ZnO composites. POLYM. COMPOS., 37:3113–3121, 2016. © 2015 Society of Plastics Engineers     

Miscibility and intermolecular hydrogen‐bonding interactions in poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/poly(4‐vinyl phenol) binary blends

The miscibility and hydrogen bonding interaction in the poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/poly(4‐vinyl phenol) [P(3HB‐co‐3HH)/PVPh] binary blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The DSC results indicate that P(3HB‐co‐3HH) with 20 mol % 3HH unit content is fully miscible with PVPh, and FTIR studies reveal the existence of hydrogen bonding interaction between the carbonyl groups of P(3HB‐co‐3HH) and the hydroxyl groups of PVPh. The effect of blending of PVPh on the mechanical properties of P(3HB‐co‐3HH) were studied by tensile testing. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of nucleation agents on the crystallization of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB)

Boron nitride (BN), talc, hydroxyapatite (HA), and zinc stearate (ZnSt) were investigated as nucleation agents (NA) for nonfossil‐based poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB) plastics. Nonisothermal crystallization behaviors of the P3/4HB/NA blends were examined by DSC. It revealed that BN is the most efficient nucleation agent to promote the crystallization rate, however, but not the crystallization degree. The lasting crystallization of P3/4HB was also removed. The nucleation effect was strengthened with increase of BN content up to 1% and then slackened deeply when further BN was added. Isothermal crystallization analysis revealed that the addition of nucleation agent BN does not alter the crystal growth mode of P3/4HB, with maintaining the Avrami parameter n value around 2.40. Talc did enhance the crystallization of P3/4HB with however milder crystal growth rate. HA and ZnSt did not promote, but depressed the crystallization of P3/4HB plastics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

High tensile strength fiber of poly[(R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate] processed by two‐step drawing with intermediate annealing

High tensile strength fibers of poly[(R)‐3‐hydroxybutyrate‐co‐(R)‐3‐hydroxyhexanoate] [P(3HB‐co‐3HH)], a type of microbial polyesters, were processed by one‐step and two‐step cold‐drawn method with intermediate annealing. Thermal degradation behaviors were characterized by differential scanning calorimeter and gel permeation chromatography measurements. Thermal analyses were revealed that molecular weights decreased drastically within melting time at a few minute. One‐step cold‐drawn fiber with drawing ratio of 10 showed tensile strength of 281 MPa, while tensile strength of as‐spun fiber was 78 MPa. When two‐step drawing was applied for P(3HB‐co‐3HH) fibers, the tensile strength was led to 420 MPa. Furthermore, the optimization of intermediate annealing condition leads to enhance the tensile strength at 552 MPa of P(3HB‐co‐3HH) fiber. Wide‐angel X‐ray diffraction measurements of these fibers suggest that the fibers with high tensile strength include much amount of the planer‐zigzag conformation (β‐form) as molecular conformation together with 2₁ helix conformation (α‐form). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41258.     

Processability modifications of poly(3‐hydroxybutyrate) by plasticizing,blending, and stabilizing

Poly(3‐hydroxybutyrate) (PHB) was plasticized with dioctyl (o‐)phthalate, dioctyl sebacate, and acetyl tributyl citrate (ATBC). The thermal properties, mechanical properties, and melt flow ability were studied with differential scanning calorimetry, thermogravimetric analysis, a universal material testing machine, and a melt flow indexer. ATBC was revealed to be an efficient plasticizer, reducing the glass‐transition temperature and increasing the thermoplasticization ability of PHB. We also blended poly(3‐hydroxybutyrate‐co‐hydroxyhexanoate) (PHBHHx) and poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3/4HB)] with PHB, ATBC, and antioxidant 1010 to overcome the brittleness of PHB and improve the melt flow stability of the materials. PHBHHx did little to improve the thermal processing but increased the fluidity of PHB, and P(3/4HB) toned the toughness of PHB. The addition of antioxidant 1010 enhanced the thermal stabilization of PHB. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal stability of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/modified montmorillonite bio‐nanocomposites

Poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P34HB)/modified montmorillonite (EMMT) bio‐nanocomposites were prepared via melt intercalation method. The thermal stability of the bio‐nanocomposites was investigated. The results showed that the decomposition temperature (T _5%) of P34HB/EMMT bio‐nanocomposite reached 271.4°C, 39.9°C higher than that of pure P34HB. The remarkable thermal stability enhancement was presumably originated from the uniform dispersion of EMMT in the matrix and intercalated structures of P34HB/EMMT bio‐nanocomposites, which was related to the increased compatibility of EMMT and P34HB caused by the ester group in EMMT. TGA‐FTIR analysis on the thermal degradation procedures of the bio‐nanocomposites manifested that the introduction of EMMT did not alter the degradation mechanism of P34HB. However, the intercalated structures hindered the mobility of P34HB macromolecular and slowed down the decomposing process of P34HB. POLYM. COMPOS., 38:673–681, 2017. © 2015 Society of Plastics Engineers     

Production and characterization of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) co‐polymer by a N2‐fixing cyanobacterium,Nostoc muscorum Agardh

BACKGROUND: Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(3HB‐co‐3HV)] co‐polymer has immense potential in the field of environmental and biomedical sciences as biodegradable and biocompatible material. The present study examines a filamentous N₂‐fixing cyanobacterium, Nostoc muscorum Agardh as a potent feedstock for P(3HB‐co‐3HV) co‐polymer production and characterization of co‐polymer film for commercial applications. RESULTS: Under photoautotrophic growth conditions, N. muscorum Agardh accumulated the homopolymer of poly‐β‐hydroxybutyrate (PHB), whereas synthesis of P(3HB‐co‐3HV) co‐polymer was detected under propionate‐ and valerate‐supplemented conditions. Exogenous carbons such as acetate, fructose and glucose supplementation with propionate/valerate was found highly stimulatory for the co‐polymer accumulation; the content reached 58–60% of dry cell weight (dcw) under P‐/N‐deficiencies with 0.4% acetate + 0.4% valerate supplementation, the highest value reported so far for P(3HB‐co‐3HV) co‐polymer‐producing cyanobacterial species. The material properties of the films were studied by mechanical tests, surface analysis and differential scanning calorimetry (DSC). CONCLUSION: N. muscorum Agardh, a photoautotrophic N₂‐fixing cyanobacterium, emerged as a potent host for production of P(3HB‐co‐3HV) co‐polymer with polymer content 60% of dry cell weight. The material properties of the films were found to be comparable with that of the commercial polymer, thus advocating its potential applications in various fields. Copyright © 2012 Society of Chemical Industry     

Study on the poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)‐based nanocomposites reinforced by surface modified nanocrystalline cellulose

As a kind of reinforcing agent, the application of nanocrystalline cellulose (NCC) is widely limited in hydrophobic polymers owing to its rich hydroxyl surface. In this study, NCC was modified with lauric acid/p‐toluensulfonyl chloride mixture, then the modified nanocrystalline cellulose (mNCC) was incorporated into biopolyester poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P(3,4)HB) by solution casting to prepare P(3,4)HB/mNCC nanocomposites. The prepared mNCC and P(3,4)HB/mNCC nanocomposites were characterized by Fourier transform‐infrared, X‐ray diffraction, contact angle test, transmission electron microscopy, scanning electron microscopy, differential scanning calorimetric, polarized optical microscope, dynamic mechanical analysis, and thermogravimetric analysis. The results show that the crystallinity and mechanical properties of P(3,4)HB are greatly improved due to the fact that NCC can be modified successfully and the mNCC can distribute uniformly in nanoscale in the matrix with good compatibility along the interface. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2015–2022, 2013