Enzymatic Degradation of Poly(butylenesuccinate)/Thermoplastic Starch Blend

The degradation of thermoplastic starch blend in the presence of commerciala-amylase and unpurified amylase of microbial origin was investigated.The blends consisting of thermoplastic starch and poly(butylene succinate)have potential use in packaging applications thus,it is essential to establish susceptibility to degradation.Molar mass loss,gravimetric weight loss,and molecular structure were evaluated.The changes in the surface were observed with scanning electron microscopy.It was confirmed that there was a significant difference in gravimetric weight loss between the blends degraded in two different solutions.Unpurified enzymes of microbial origin,produced by Rhizopus oryzae cultures decomposed analyzed materials more efficiently than purified commercial ones.Moreover,it was proved that in applied conditions,the molar mass of PBS fraction did not change significantly.

Improving Polylactide Toughness by Plasticizing with Low Molecular Weight Polylactide-Poly(Butylene Succinate)Copolymer

A low-molecular-weight polylactide-poly(butylene succinate)(PLA-PBS)copolymer was synthesized and incorporated into polylactide(PLA)as a novel toughening agent by solvent casting.The copolymer had the same chemical structure and function as PLA and it was used as a plasticizer to PLA.The copolymer was blended with PLA at a weight ratio from 2 to 10 wt%.Phase separation between PLA and PLA-PBS was not observed from their scanning electron microscopy(SEM)images and the crystal structure of PLA almost remained unchanged based on the X-ray diffraction(XRD)measurement.The melt flow index(MFI)of the blends was higher as the amount of PLA-PBS increased,indicating that the block copolymer did improve the mobility of the PLA chains.Moreover,tensile tests revealed that PLA with greater PLA-PBS copolymer exhibited higher elongation at break and it reached the maximum at 8 wt%of PLA-PBS in PLA,which was around 6 times higher than that of pure PLA.Furthermore,the glass transition temperature,measured by differential scanning calorimetry(DSC),markedly decreased with an increasing amount of the copolymer as it decreased from 61.2℃ for pure PLA to 41.3℃when it was blended with 10 wt%PLA-PBS copolymer.Therefore,the PLA-PBS copolymer was shown to be a promising plasticizer for fully biobased and toughened PLA.

DSC Study of Thermal Properties of Biodegradable Poly(Butylene Succinate-co-terephthalate)

Poly(butylene succinate) (PBS),poly(butylene terephthalate) (PBT) and poly(butylene succinate-co-terephthalate) (PBST)s were synthesized from dimethyl succinate and/or dimethyl terephthalate reacting with 1,4-butanediol through a process of transesterification/polycondensation in the presence of a high effective catalyst and characterized by means of GPC and DSC. The investigation was mainly focused on the influence of content of terephthalate units on the molecular weight and thermal properties of resulting polymers. It is revealed that the melting temperature and crystallinity of synthesized polymers decrease first with the increase of terephthalate units, then shift to rise gradually by DSC measurements. The results of Flory equation suggest sequence structure of PBSTs is random.

Construction and evaluation of co-electrospun poly (butylene succinate)/gelatin materials as potential vascular grafts

In this study,a series of poly(butylene succinate)(PBSU)/gelatin composites were prepared by electrospinning.The morphology,physicochemical analysis,biomechanical properties,biocompatibility,and biodegradability of the materials were evaluated.The results showed that the ultimate tensile stress of the vascular PBSU/gelatin grafts at(95/5),(90/10),(85/15),and(80/20)was(4.17±0.54)MPa,(3.81±0.44)MPa,2.94±0.69 MPa and 2.11±0.72 MPa respectively,and the burst pressure was(282.7±22.3)kPa,(295.3±3.9)kPa,(306.8±13.9)kPa and(307.6±9.0)kPa respectively,which met the requirements of tissue-engineered blood vessels.Furthermore,the addition of gelatin improved the hydrophilicity and degradation properties of PBSU,thus enhancing cell adhesion and promoting the inward growth of vascular smooth muscle cells.In summary,the research in this paper provides a useful reference for the preparation and optimization of vascular scaffolds.

Crystallization and Dynamic Mechanical Behavior of Coir Fiber Reinforced Poly(Butylene Succinate)Biocomposites

The crystallization behavior,crystal morphology and form,and viscoelastic behavior of poly(butylene succinate)(PBS)and coir fiber/PBS composites(CPB)were investigated by differential scanning calorimetry(DSC),polarized optical microscopy(POM),X-ray diffraction(XRD)and dynamic mechanical analysis(DMA).The results of DSC measurement show that the crystallization temperature increases with the filling of coir fibers.POM images reveal that the spherulitic size and crystallization behavior of PBS are influenced by the coir fibers in the composites.XRD curves show that the crystal form of pure PBS and CPB are remaining almost identical.In addition,the storage modulus of CPB significantly increases comparing with the pure PBS.This predicted the dimensional stability and improved load-deformation temperature.In conclusion,the addition of coir fibers has a significant effect on the thermal properties of the matrix.

Influencing Factors and Process on <i>in Situ</i>Degradation of Poly(<i>Butylene Succinate</i>) Film by Strain <i>Bionectria ochroleuca</i>BFM-X1 in Soil

This is the first report on the PBS film degraded by any Bionectria ochroleuca fungal strain. The fungal strain BFM-X1 was isolated from an air environment on a vegetable field and was capable of degrading poly(butylene succinate) (PBS). The taxonomic identity of the strain BFM-X1 was confirmed to be Bionectria ochroleuca (showing a 99% similarity to B. ochroleuca in a BLAST search) through an ITS rRNA analysis. The bio-degradation of the PBS film by strain BFM-X1 was studied. Approximately 97.9% of the PBS film was degraded after strain BFM-X1 was inoculated at 28?C for 14 days. The degradation efficiency of BFM-X1 against PBS film under different soil environmental conditions was characterized. The results indicated that 62.78% of the PBS film loss was recorded in a 30-d experimental run in a sterile soil environment indoors. On adding strain BFM-X1 to a soil sample, the PBS degradation rate accelerated approximately fivefold. Furthermore, both temperature and humidity influenced the in situ degradation of the PBS by strain BFM-X1, and temperature may be the major regulating factor. The degradation was particularly effective in the warm season, with 90% of weight loss occurring in July and August. Scanning electron microscope observations showed surface changes to the film during the degradation process, which suggested that strain BFM-X1preferentially degraded an amorphous part of the film from the surface. These results suggested that the strain B. ochroleuca BFM-X1 was a new resource for degrading PBS film and has high potential in the bioremediation of PBS-plastic-contaminated soil

THERMAL PROPERTY, MISCIBILITY AND CRYSTALLIZATION BEHAVIOR OF POLY(3-HYDROXYBUTYRATE-co-3-YDROXYHEXANOATE) AND POLY(BUTYLENE SUCCINATE-ADIPATE) (PHBHHX/PBSA) BLENDS

Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/20 to 20/80 by melt mixing method. Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMA), polarizing optical microscopy (POM) and wide angle X-ray diffractometer (WAXD) were used to study the miscibility and crystallization behavior of PHBHHx/PBSA blends. Experimental results indicate that PHBHHx is immiscible with PBSA as shown by the almost unchanged glass transition temperature and the biphasic melt.

Nonisothermal Crystallization Kinetics of Poly(butylene adipate-co-terephthalate) Copolyester

Nonisothermal crystallization behavior of poly(butylene adipate-co-terephthalate)(PBAT) synthesized via direct esterification and polycondensation reactions was investigated by the differential scanning calorimetry(DSC).The Avrami equation modified by Jeziorny and the Z.S.Mo equation were employed to describe the non-isothermal crystallization kinetics of copolyester samples.The test results showed that the Avrami equation was successful in describing nonisothermal crystallization process of PBAT copolyesters.PBAT copolyester could give birth to secondary crystallization.The crystallization parameter(Zc) increased with an increasing cooling rate and the Avrami exponent(n) was around 2.3.For a given cooling rate,the value of Zc demonstrated a sagging trend with an increase in adipic acid(AA) content.The equation proposed by Z.S.Mo was successful in describing the nonisothermal crystallization kinetics of PBAT copolyesters.

TRANSESTERIFICATION OF POLY(BISPHENOL A CARBONATE) WITH AROMATIC AND ALIPHATIC SEGMENTS IN BUTYLENE TEREPHTHALATE-CAPROLACTONE COPOLYESTER

In this article, the transesterification of poly(bisphenol A carbonate) (PC) with butylene terephthalate-caprolactone copolyester at a weight ratio 50/50 (BCL(21)) was thoroughly investigated by proton nuclear magnetic resonance spectroscopy ('H-NMR), in conjunction with a model compound. The 1 H-NMR results of the annealed blend PC/BCL(21) show that the formation of bisphenol A-terephthalate ester units is the same as in the annealed blend of PC with PBT, and the transesterification actually occurs between PC and butylene terephthalate (BT) segments in BCL(21). By comparison with the model compound bisphenol A dibutyrate, the new signal appearing at δ= 2.56 in the 1H-NMR spectrum confirms the existence of bisphenol A caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. 1H-NMR analysis of the transesterification rates reveals that the reaction of PC with aromatic and aliphatic segments in BCL(21) proceeds in a random manner. The miscibility of the blend PC/BCL(21) copolyester is favorable for the transesterification of PC with BT segments and CL segments.

木质素在合成可降解高分子材料中的应用研究进展

简述了木质素的结构、特性和分类情况,并综述了近年来国内外使用木质素来增强和改善聚对苯二甲酸-己二酸丁二酯、聚乳酸、聚己内酯和聚丁二酸丁二酯等合成可降解高分子材料性能的研究进展。指出木质素与合成可降解高分子材料复合可以赋予复合材料多种功能特性,如紫外屏蔽、抗菌、阻隔等,并能改善材料的生物降解性能,同时实现降本增效的目标。最后提出当前木质素与合成可降解高分子材料复合材料工业化生产应用存在的问题,并对木质素基全生物降解复合材料的未来研究趋势进行展望。

静电纺丝HNTs/PBST复合纳米纤维膜的制备及其空气过滤性能研究

采用静电纺丝工艺,以可生物降解的聚丁二酸丁二醇-共-对苯二甲酸丁二醇酯(PBST)为原料,改性埃洛石纳米管(HNTs)为驻极体,制备了HNTs/PBST复合纳米纤维膜,探讨了HNTs对PBST纳米纤维膜的形貌、结构及空气过滤性能的影响。实验结果表明,改性HNTs添加量为10%(w)即可使PBST纳米纤维直径细化,协同增强了纳米纤维膜的物理筛分效应及静电吸引能力,显著提升了材料的综合过滤性能,HNTs/PBST复合纳米纤维膜对PM0.3的过滤效率高达96.67%,且过滤阻力仅为90.5 Pa。

酰肼类成核剂己二酸二苯基二酰肼对PBS复合材料性能的影响

聚丁二酸丁二酯(PBS)是近些年兴起的一类绿色环保高分子材料,具有良好的生物可降解性和生物相容性,是最具发展潜力的环境友好材料之一。然而PBS冲击强度较低,结晶性能较差,限制了其进一步的发展和应用。针对以上不足,采用酰肼类成核剂己二酸二苯基二酰肼(TMC-306)对PBS树脂进行改性,研究了酰肼类成核剂的添加量对PBS复合材料力学性能、结晶性能、加工性能以及微观形貌的影响。结果表明,TMC-306的引入明显改善了PBS/TMC-306复合材料的力学性能和结晶性能,当TMC-306添加量为15份时,PBS复合材料的冲击强度从41 J/m提高至102 J/m,提升了149%,结晶度从48.40%提高至62.01%,提升了28.12%。X射线衍射测试结果表明,成核剂TMC-306使复合材料晶面的衍射峰面积略微增大,与纯PBS晶型基本一致。流变测试结果发现,随着成核剂添加量的增加,PBS复合材料的储能模量、损耗模量和复数黏度均逐步增大,熔体强度得到了提高,这说明成核剂同时也改善了复合材料的加工性能。扫描电子显微镜测试结果表明,随着TMC-306的增加,PBS复合材料的断面由平整光滑变为“阶梯”式结构,且在添加量为15份时最为明显,这与力学测试结果相一致。

阻燃聚丁二酸丁二醇酯的研究进展

综述了近年来聚丁二酸丁二醇酯(PBS)复合材料阻燃改性技术的研究进展,并分析了其阻燃机理。常用于PBS复合材料的阻燃剂以磷氮系阻燃剂、纳米阻燃剂、生物基阻燃剂及其复配体系为主。其中磷氮系阻燃剂的开发和改性方案最多,尤其是基于聚磷酸铵(APP)的阻燃体系是目前研究最多也是最有效的体系,包括APP和纳米阻燃剂的复配体系以及APP和生物基阻燃剂的复配体系。本文同时对各种阻燃体系的阻燃性能及典型阻燃机理进行了总结。

聚丁二酸-共-对苯二甲酸丁二醇酯/氧化镁复合薄膜的制备及性能

以聚丁二酸-共-对苯二甲酸丁二醇酯(PBST)为基体,纳米氧化镁(MgO NPs)为抗菌剂,通过溶剂挥发法制备了PBST/MgO纳米复合薄膜,并探讨了复合薄膜在食品包装中的应用。研究了MgO NPs对纳米复合薄膜的机械性能、水蒸汽透过率(WVP)、氧气透过率(OTR)和紫外阻隔性能的影响。结果表明:MgO NPs的加入改善了PBST基体的力学性能和阻隔性能。与PBST薄膜相比,复合膜的拉伸强度和断裂伸长率分别提高了43.7%和32.2%,水蒸汽透过率和氧气透过率分别降低了28.1%和23.6%,并具有良好的紫外阻隔性能。当MgO NPs质量含量为5%时,复合膜的性能最佳。

超临界流体发泡制备生物可降解塑料泡沫应用进展

塑料制品的不规范生产、使用以及回收不当等,会造成能源资源浪费和环境污染。推广可降解塑料替代产品是解决塑料污染问题的重要途径之一。目前,生物可降解塑料仅用于薄膜、吸管等一次性制品,需求量更大的缓冲包装领域尚未有规模化应用。近年来,绿色环保的超临界流体发泡技术制备的生物可降解塑料泡沫成为了学术界和工业界关注的热点,基于此,笔者总结了超临界流体发泡制备生物可降解塑料泡沫方面的应用进展,简述了间歇发泡、挤出发泡、注塑发泡、珠粒发泡制备生物可降解塑料泡沫的发泡工艺和结构性能,重点综述了聚乳酸、聚对苯二甲酸-己二酸丁二酯、聚丁二酸丁二酯泡沫材料的研究现状。

聚丁二酸丁二醇酯和聚辛二酸丁二醇酯及聚(丁二酸-co-辛二酸丁二醇)共聚酯的酶促降解

以1,4-丁二醇与不同链长二元酸单体为原料,合成了聚丁二酸丁二醇酯(PBS)和聚辛二酸丁二醇酯(PBSub)2种均聚酯和4种不同比例聚(丁二酸-co-辛二酸丁二醇)共聚酯。以上述6种聚酯为降解底物,利用角质酶对其进行降解研究。通过衰减全反射傅里叶变换红外光谱、核磁共振波谱仪、差示扫描量热仪、X射线衍射仪和热重分析仪等对聚酯及其降解产物进行表征分析。6种聚酯的晶体结构、熔点、结晶度和热稳定性变化不大。研究表明,聚酯的结晶度和熔点温度是影响其酶降解的重要因素。角质酶降解共聚酯的结晶区和非结晶区,但优先降解非结晶区。丁二酸/辛二酸投料摩尔比为4/6和6/4的降解效果最好,但摩尔比为6/4的样品熔点较高,为最佳比例。

PPC/PBS复合生物膜的屏障功能及其对兔胫骨骨缺损模型的促成骨作用

目的:探讨聚碳酸1,2-丙二酯(PPC)/聚丁二酸丁二醇酯(PBS)复合生物膜在兔胫骨骨缺损模型中的空间支撑能力及其对成骨效果的影响,阐明其屏障功能的可靠性和体内促成骨作用。方法:制备PPC/PBS和PPC/PBS/Ⅰ型胶原(Col-Ⅰ)(PPC/PBS/Co)复合生物膜。选用18只日本大耳白兔,于兔每侧胫骨制备2处骨缺损,随机选择6只兔于骨缺损处放置PPC/PBS复合生物膜,术后4、8和12周各处死2只兔,扫描电子显微镜(SEM)观察兔骨缺损区PPC/PBS复合生物膜表面微观结构。实验分为空白对照组、PPC/PBS复合生物膜组、BME-10X胶原膜组和PPC/PBS/Co复合生物膜组,分别行手术将上述生物膜放置于兔相应骨缺损处,空白对照组兔不放置复合生物膜,于术后2、4、8和12周时分别处死3只兔,采用软X线检测各组兔骨缺损区再生骨组织灰度值,荧光标记后采用激光共聚焦显微镜观察各组兔骨缺损区再生骨组织荧光强度,采用HE染色和改良Gomori三色染色法观察各组兔骨缺损区再生骨组织病理形态表现,免疫组织化学染色法检测各组兔骨缺损区再生骨组织中骨形态发生蛋白2(BMP-2)和骨桥蛋白(OPN)蛋白表达水平。结果:大体观察,PPC/PBS复合生物膜紧密覆盖于骨缺损区,未见移位及塌陷。SEM观察,PPC/PBS复合生物膜多孔面随时间延长表面出现微孔结构并数量增多,而光滑面基本未形成微孔样结构。软X线检测,各组兔骨缺损区再生骨组织灰度值均随时间延长而升高,12周时PPC/PBS/Co复合生物膜组兔骨缺损区再生骨组织灰度值明显高于其他各组(P<0.05)。共聚焦显微镜观察,4、8和12周时PPC/PBS/Co复合生物膜组兔骨缺损区再生骨组织荧光强度与空白对照组相近;与PPC/PBS复合生物膜组和BME-10X胶原膜组比较,4周时PPC/PBS/Co复合生物膜组兔骨缺损区再生骨组织荧光强度升高(P<0.05),8和12周时PPC/PBS/Co复合生物膜组兔骨缺损区再生骨组织荧光强度降低(P<0.05)。HE染色和改良Gomori染色,与PPC/PBS复合生物膜组和BME-10X胶原膜组比较,2和4周时PPC/PBS/Co复合生物膜组和空白对照组兔骨缺损区形成新骨的速度较快,在12周时骨缺损区形成的层板状骨矿化程度较高。免疫组织化学染色,2和4周时,与空白对照组、PPC/PBS复合生物膜组和BME-10X胶原膜组比较,PPC/PBS/Co复合生物膜组兔骨缺损区再生骨组织中BMP-2和OPN蛋白表达水平升高(P<0.05或P<0.01);与空白对照组和PPC/PBS复合生物膜组比较,BME-10X胶原膜组兔骨缺损区再生骨组织中BMP-2和OPN蛋白表达水平均降低(P<0.05或P<0.01)。结论:PPC/PBS复合生物膜具有较好的空间支撑能力,物理屏障功能可靠,且PPC/PBS/Co复合生物膜具有良好的体内促成骨作用。

后道拉伸对聚丁二酸丁二醇酯/丝胶蛋白共混纤维结构与性能的影响

为提高纤维的力学性能,采用后道拉伸处理聚丁二酸丁二醇酯(poly(butylene succinate),PBS)/丝胶蛋白(silk sericin,SS)共混纤维,研究拉伸倍数和拉伸温度对纤维形态结构、化学结构、热性能、力学性能与降解性能的影响。结果表明,随着拉伸倍数增加,PBS与丝胶蛋白发生相对位移,纤维表面沿拉伸方向出现明显条纹;随着拉伸温度增加,纤维表面的条纹减少,表明温度的增加提高了PBS分子链的运动能力,使纤维保持致密结构。随着拉伸倍数和拉伸温度的提高,共混纤维的力学性能和结晶度呈现先增加后减小的趋势,在后道拉伸倍数为4倍,拉伸温度为75℃时,纤维的结晶度可达61.30%,此条件下的纤维断裂强度最大为2.0 cN/dtex,接近粘胶纤维的力学强度,可满足纺纱、非织造等纺织加工工艺的要求。

1,2-环己二醇改性聚丁二酸丁二酯的结构与性能

以1,4-丁二酸(SA)、1,4-丁二醇(BDO)、1,2-环己二醇(CHD)为原料,通过改变BDO与CHD投料比,采用熔融缩聚法制备了一系列的CHD改性聚丁二酸丁二醇酯(PBS)共聚酯。采用1H-NMR表征了共聚酯的化学结构,并且,分析了CHD占主链二醇含量对共聚物分子量及其分子量分布、熔融和结晶性能、热稳定性能、拉伸性能及脂肪酶降解性能的影响。结果表明,随着CHD含量的增加,共聚酯的数均分子量从7.45×10^(4)下降至4.75×10^(4),由结晶度48.5%的半晶态转变为无定形态,热分解损失为质量5%时,温度降低了26.7℃,拉伸强度由38.2 MPa降低至14.9 MPa,但脂肪酶降解性能显著提高。PBS主链引入适量CHD后,可以有效地调控PBS的结晶度及柔顺性,提高了PBS在非堆肥条件下的降解速度。

扩链条件对聚丁二酸丁二酯-共-对苯二甲酸丁二酯/滑石粉共混物性能的影响

将一种多环氧官能团聚合物作为聚丁二酸丁二酯-共-对苯二甲酸丁二酯(PBST)的扩链剂,研究熔体反应挤出过程中的扩链条件对PBST/滑石粉共混物性能的影响。将扩链剂用量、反应温度和螺杆转速作为本研究的主要研究因素,通过方差分析寻找主要影响因素及各因素间交互作用。结果表明,扩链剂用量的影响最为显著,其次是温度,螺杆转速的影响不显著;随着扩链剂用量的增加,熔融温度和结晶温度降低,分子量、熔体黏度和热稳定性增加;同时,随着扩链剂用量的增加,改性PBST强度提高但韧性降低;响应面分析表明扩链剂用量、反应温度和螺杆转速分别为0.66%、200℃和300 r/min时扩链条件最优。