聚(3-羟基丁酸酯-co-4-羟基丁酸酯)/酰胺成核剂共混体系

采用熔融共混方法制备了聚(3-羟基丁酸酯-co-4 -羟基丁酸酯)[P( 3HB-co-4HB)]和酰胺成核剂的复合体系,并通过万能材料试验机、差示扫描量热仪( DSC)、偏光显微镜(POM)和X射线衍射仪(XRD)等测试手段考察了不同含量酰胺成核剂对P( 3HB-co-4HB)基体的力学、热力学及结晶性能的影响.结果表明:酰胺成核剂在共混体系中起到成核剂作用,可有效改善P(3 HB-co-4HB)结晶性能,提高其韧性.     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)研究进展

介绍了生物可降解材料聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P(3HB-co-4HB))的性能及特点;综述了针对P(3HB-co-4HB)加工温度窄、脆性大、成本高等缺点而进行的增塑改性、扩链改性、共混改性的技术进展以及P(3HB-co-4HB)纺丝成纤技术;阐述了利用P(3HB-co-4HB)可塑性、生物降解性和生物相容性等在医疗领域的应用情况及发展前景;指出P(3HB-co-4HB)的研究将集中在其材料加工流动性、结晶性能的改善及其纤维加工技术与纤维表面整理技术等方面。     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)的性能

采用毛细管流变仪、差示扫描量热仪、热失重分析仪及偏光显微镜(POM)研究了聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]的流变性能、热性能及结晶性能.P(3HB-co-4HB)熔体属于典型的假塑性流体,剪切应力与剪切速率关系符合Ostwald-de Wale幂率定律,熔体表观黏度与温度的关系符合Arrhenius方程;P(3HB-co-4HB)的玻璃化转变温度约为-10℃,熔点在100～120℃,降解温度约为205℃;POM观察发现,P(3HB-co-4HB)在约78℃时球晶半径径向生长速率最大.     

柠檬酸三乙酯改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)的性能研究

用熔融模压法制备了柠檬酸三乙酯（TEC）增塑的4HB含量不同的聚（3-羟基丁酸酯-co-4-羟基丁酸酯）[P（3HB-co-4HB）]共混物，用差示扫描量热仪（DSC）、广角X射线衍射仪（WAXI））和拉伸试验对共混物的热性能、结晶结构和力学性能进行了表征，考察了增塑剂TEC的用量和4HB含量对共聚酯性能的影响。结果表明：随着TEC用量的增大，P（3HB—co-17％4HB）共聚酯体系的结晶度减小，其熔融温度、玻璃化温度和结晶温度降低，屈服强度、断裂强度及模量也降低，屈服伸长率增大；随4HB含量的增大，相同用量的TEC共混体系的熔点、玻璃化温度和结晶温度降低，屈服强度、断裂强度和模量减小。     

聚乳酸/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)/改性高岭土纳米复合材料的结晶、动态力学及流变行为

为提高聚乳酸(PLA)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P(3HB-co-4HB))基体的综合性能,采用熔融共混法制备聚乳酸/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)/改性高岭土(modified kaolin)纳米复合材料。利用DSC、DMA、旋转流变仪、扫描电镜(SEM)等对复合体系的结晶、动态力学性能、流变行为、表面结构等进行了研究。结果表明:复合体系的冷结晶温度逐渐变小,降低了12.5℃,结晶能力有所提高。此外,结晶度由21.65%增加到35.22%,提高了62.68%。DMA结果显示,随着改性高岭土添加量的增多,复合体系的储能模量E′和玻璃化转变温度出现先增大后减小的变化。熔融态下,复合体系的黏度随剪切速率的增大而减小,属假塑性流体。当体系中改性高岭土添加量为4%时,材料的缺口冲击强度有明显的改善。利用SEM发现,少量改性高岭土可以均匀地分散在PLA/P(3HB-co-4HB)基体中并能显著提高复合体系的韧性。     

聚(3-羟基丁酸酯-co-4-羟基丁酸酯)的扩链改性

采用环氧丙烯酸型扩链剂改性聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)],考察了扩链剂对熔体黏弹性、力学性能和成型发泡的影响.用流变仪测试熔体稳态黏度与剪切速率、动态黏弹模量与角频率、模量与时间的关系,用扫描电子显微镜观察改性前后P(3HB-co-4HB)的断面形貌.结果表明,扩链剂的加入提高...     

聚乳酸/聚羟基脂肪酸酯共混物辐照交联

聚乳酸(PLA)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3HB-co-4HB)]共混后,通过电子束辐照在0~100 kGy的剂量范围内使之交联,然后测试凝胶含量、材料回缩性能、力学性能,并进行差示扫描量热分析。结果显示,辐照交联PLA/P(3HB-co-4HB)后,材料具有形状记忆功能,其屈服强度提高,断裂伸长率降低;辐照交联提高了PLA/P(3HB-co-4HB)耐热性,降低了材料结晶性能。     

聚3-羟基丁酸酯4-羟基丁酸酯性能研究

概述了聚羟基脂肪酸酯(PHA)类生物塑料的发展过程,分析了聚3-羟基丁酸酯4-羟基丁酸酯(P34HB)的结构、综合性能、加工特性,详细介绍了P34HB的改性方法。结果表明:P34HB是新一代优异的生物塑料,通过改性,其力学性能与聚丙烯和聚乙烯相近,可以在传统塑料加工设备上加工成型。但对P34HB的研发及应用还需做大量工作。     

生物塑料聚(3-羟基丁酸酯-co-4-羟基丁酸酯)改性研究

文章介绍了生物塑料聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P3/4HB)的性能;综述了针对P3/4HB加工成型温度窄、产品脆性大、应用成本高等缺点而进行的物理改性、化学改性等技术进展;提出了对P3/4HB发展过程中需要解决的问题;同时指出P3/4HB的研究将集中在其材料结晶性能、加工流动性改善的发展方向。     

聚(3-羟基丁酸酯-共-4-羟基丁酸酯)/马来酸酐共混物性能的研究

采用熔融共混方法制备了一系列聚(3-羟基丁酸酯-共-4-羟基丁酸酯)/马来酸酐(MA)的共混物。研究了MA含量对共混物力学性能的影响,并且采用差示扫描量热仪和热失重分析仪对共混物热性能的变化进行了研究。结果表明,MA的加入有效改善了聚(3-羟基丁酸酯-共-4-羟基丁酸酯)的力学性能和热稳定性,拓宽了其加工窗口,其中加入0.5份MA就可将共混物的起始热分解温度提高19.31℃。同时,MA能够改善3-羟基丁酸酯微区和4-羟基丁酸酯微区的相容性。     

Microbial synthesis and properties of poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

Microbial synthesis of copolymers of [R]-3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB), P(3HB-co-4HB), by Alcaligenes eutrophus, Alcaligenes latus, and Comamonas acidovorans from various carbon sources has been studied. The copolyester compositions varied from 0 to 100 mol% 4HB, depending on the microorganism and the combination of carbon substrates supplied. The thermal and physical properties of compositions with 0–100 mol% 4HB were investigated. The copolyesters represented a wide variety of polymeric materials, from hard crystalline plastic to very elastic rubbers, depending on composition. The copolyester films with high 4HB fractions (64–100 mol% 4HB) exhibited the characteristics of a thermoplastic elastomer, and the tensile strength increased from 17 to 104 MPa as the 4HB fraction increased. The enzymatic degradation of P(3HB-co-4HB) films was studied in an aqueous solution of extracellular polyhydroxybutyrate (PHB) depolymerase from Alcaligenes faecalis or lipase from Rhizopus delemer. The erosion rate of P(3HB-co-4HB) films was strongly dependent on the copolymer composition. In addition, environmental degradation of P(3HB-co-4HB) films in sea water was investigated.     

热处理时间对聚(3-羟基丁酸酯-co-4-羟基丁酸酯)性能的影响

研究了热处理时间对P(3HB-co-4HB)摩尔质量的影响,并考察了热处理时间和摩尔质量对加工后的产物在溶剂中的溶解性、结晶性能,结晶结构、力学性能和熔体流动性的影响.研究结果表明:随着热处理时间的增加,P(3HB-co-4HB)共聚酯的摩尔质量降低,在溶剂中的溶解性变好,熔点和结晶温度有所升高,共聚酯的结晶结构没有发生改变,拉伸强度和断裂伸长率降低,熔体质量流动速率升高.当热处理时间为4 min时,共聚酯的数均摩尔质量为2.3×105g/mol时,共聚酯具有较好的加工流动性,并保持了较好的力学性能.     

Effect of acetic acid on poly-(3-hydroxybutyrate-CO-3-hydroxyvalerate) synthesis in recombinantEscherichia coli

The synthesis of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] copolymer by recombinantEscherichia coli was studied in the medium containing glucose and valeric acid as carbon sources. A recombinantE. coli strain (fadR atoC) harboring a stable high-copy number plasmid containing theAlcaligenes eutrophus polyhydroxyalkanoate (PHA) biosynthesis genes was constructed for the production of the copolymer P(3HB-co-3HV). Accumulation of acetic acid not only had a detrimental effect on cell growth but also decreased the flux of acetyl-CoA into the P(3HB-co-3HV) biosynthetic pathway. Reducing specific growth rate by increasing the initial acetic acid concentration resulted in enhanced copolymer synthesis due to less accumulation of acetic acid. Initial acetic acid concentration of 50 mM was found to be optimal at 20 g/l glucose and 20 mM valeric acid concentration. The fraction of 3-hydroxyvalerate (3HV) increased with decreasing growth temperature. The ratios of 3HV to 3HB in the copolymer could be controlled by altering the concentrations of valeric acid and glucose in the medium. Catabolite repression was in part responsible for the inefficient copolymer synthesis. Various nutritional components were examined for their ability to relieve catabolite repression. An addition of oleic acid resulted in threefold increase of the 3HV fraction in the copolymer. An addition of a small amount of tryptone and peptone considerably promoted P(3HB-co-3HV) synthesis.     

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     

Novel bioresource-based poly(3-Hydroxybutyrate-co-4-Hydroxybutyrate)/poly(LacticAcid) blend fibers with high strength and toughness via melt-spinning

Novel biodegradable blend fibers based on the biomaterials poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) and poly(lacticacid) (PLA) were successfully prepared by combining melt spinning and hot drawing. The results showed that the commixture could continuous and stable spin for a P3HB4HB ratio of 30–35 wt% and winding speed of 20–30 m/min. The thermal stability of the P3HB4HB/PLA blend fiber was increased, as determined by thermogravimetric analysis. The crystallinity degree of the P3HB4HB/PLA blend fibers increased with increasing the P3HB4HB content. The addition of PLA resulted in a low cold crystallization temperature and diminutive size of the lamellar stacks, which would be favorable for the enhancement of the mechanical properties of the blend fiber, when the P3HB4HB content was 30–35 wt%. The P3HB4HB/PLA composite fiber was one type of high-strength and high-toughness fiber, with 1 GPa breaking stress and over 80% strain at break. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48956.     

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     

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     

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