PBS降解塑料降解性能的研究

以聚丁二酸丁二醇酯(PBS)为原料,通过生物降解、热氧化降解和光降解研究了PBS的降解性能。利用乌式黏度计测定了PBS塑料在降解过程中分子量的变化;利用傅里叶变换红外光谱仪表征了PBS在降解过程中的红外光谱特性。实验结果表明:PBS薄膜生物降解15d后没有明显变化。PBS塑料在200℃下,热氧化降解36h,分子量减少了约77.6%。PBS塑料在光氧化降解5d后,分子量减少了约98%。与生物降解、热氧化降解相比,PBS塑料在光降解下的降解程度更为明显。     

生物降解聚丁二酸丁二醇/1,3-丙二醇酯的合成与表征

以丁二酸、丁二醇和1,3- 丙二醇（1,3-PDO）为原料,采用熔融缩聚法,合成了-系列新型可降解的聚丁二酸丁二醇酯/丁二酸1,3- 丙二醇酯共聚物 P（BS-co-PDO）.选用红外光谱仪和核磁共振仪对共聚物的化学结构进行了表征.研究了1,3-PDO的添加量对共聚物的相对分子质量、热性能、结晶性能、力学性能、透光率以及降解性能的影响.结果表明：随着1,3-PDO添加量的增加,共聚物的分子量、熔点和结晶度呈降低趋势;相对于聚丁二酸丁二醇酯而言,引入1,3-PDO组分的共聚物的热性能提高,柔韧性增强,断裂伸长率增大,透光率提高;降解测试结果表明,1,3-PDO组分含量越多,共聚物的降解性能越好.     

LDPE/有机金属降解剂/配合剂体系降解性的研究

以低密度聚乙烯（LDPE）／铁（或锡）的有机合物／含氮有机物为降解体系,制成薄膜样品,于模拟堆肥环境中降解,跟踪取样,测定其粘均分子量及氢过氧化物浓度([POOH])变化,另外,进行了傅立叶变换红外（FT－IR）和差示扫描量热分析（DSC）测试,结果表明,所选用的某些体系能够在堆肥条件下高效降解,薄膜样品在降解60d后分子量大幅度降低,羟基含量,结晶度呈现明显的增高趋势,降解程度受降解剂种类,配合剂种类及含量,降解环境等诸多因素影响,所测[POOH]变化趋势与分子量变化存在着关联性,这为降解机理的进一步讨论打下了基础。     

竹纤维/聚乳酸可生物降解复合材料自然降解性能

通过注射成型工艺制备竹纤维/聚乳酸（BF/PLA）可生物降解复合材料。利用X射线衍射（XRD）、凝胶渗透色谱（GPC）、三维视频显微镜及扫描电镜（SEM）等分析手段研究了BF/PLA复合材料自然降解性能。研究结果表明：BF/PLA复合材料自然降解过程中BF首先降解,PLA逐步分层缓慢降解,复合材料质量逐渐减少;PLA分子链上酯基与水反应,分子链不断断裂,结晶度减小,平均分子量降低,分子量分布变窄;复合材料颜色变深,表面变得粗糙不平,部分裸露的BF清晰可见,其拉伸强度和冲击强度逐渐下降。12个月后,BF/PLA复合材料质量损失率达到8.87%,PLA重均分子量降低了25.9%,复合材料的冲击强度和拉伸强度分别降低了44.0%和43.8%。BF/PLA可生物降解复合材料在土壤中的自然降解效率较低。     

生物可降解聚丁二酸丁二醇酯的合成及两亲性改性研究

脂肪族聚酯由于其生物降解性和经济性，已成为国内外降解材料研究的重点。以丁二酸和丁二醇为原料，通过熔融缩聚法合成聚丁二酸丁二醇酯（PBS），并通过与己内酯、聚乙二醇共聚，改善其降解性能。利用FT-IR、^1H-NMR、DSC、粘度法测定分子量等方法对共聚物组成、热学性能及亲水性能进行了研究。实验结果表明，改性后的聚酯高分子链有更好的柔韧性和亲水性，可以加快降解速率。     

聚丙烯分子量对其注射成型试样的拉伸和抗冲特性的影响EI

通过对聚丙烯及其经化学降解后的一系列不同分子量聚丙烯的注射成型样条的密度、结晶度、形态、取向、常温拉伸特性和低温抗冲性等方面的实验,讨论了分子量对这些性能的影响。分子量对密度、结晶度影响不大,但对形态及内外层的取向结构影响较大,而低温抗冲性能随分子量下降较多,常温抗拉特性随分子量变化较复杂,就其综合性能而言,以分子量在某一范围内较好。     

聚丙烯分子量对其注射成型试样的拉伸和抗冲特性的影响

通过对聚丙烯及其经化学降解后的一系列不同分子量聚丙烯的注射成型样条的密度、结晶度、形态、取向、常温拉伸特性和低温抗冲性等方面的实验,讨论了分子量对这些性能的影响。分子量对密度、结晶度影响不大,但对形态及内外层的取向结构影响较大,而低温抗冲性能随分子量下降较多,常温抗拉特性随分子量变化较复杂,就其综合性能而言,以分子量在某一范围内较好。     

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。     

超支化聚氨酯共混改性聚丁二酸丁二醇酯的性能

采用熔融共混与开炼压延制备聚丁二酸丁二醇酯(PBS)和羟基封端超支化聚氨酯(HBPU)的复合膜。使用X射线衍射(XRD)、差示扫描量热(DSC)、热重分析(TG)和万能试验机对其结晶性、热性能和力学性能进行了研究;采用土埋法在陕西花园土中对复合膜进行降解。结果表明,随着HBPU的增加,复合膜结晶度均有所降低,当HBPU的质量分数为6%时达到25.7%;DSC结果表明,HBPU提高了PBS的结晶温度;随着HBPU的增加,复合材料的热稳定性有所下降;在拉力测试中,复合材料的断裂伸长率得到了显著提高,6%时复合材料的断裂伸长率达到75%;复合膜降解后表面出现明显裂纹。HBPU对PBS改性,降低了PBS的结晶度,提高了复合材料的韧性。     

癸二酸改性丁二酸丁二醇基聚酯材料的结晶性能和降解性能

以癸二酸、丁二酸为二元酸,丁二醇为二元醇,通过熔融共聚的方式合成了聚(癸二酸丁二醇酯丁二酸丁二醇酯)无规共聚物(SE10)和聚丁二酸丁二醇(PBS),并通过酶解实验研究了相对分子质量、结构、表面形态的变化。通过红外光谱、差示量热扫描仪、偏光显微镜、凝胶色谱和扫描电镜对二者降解前后性能进行了研究,相比PBS,SE10晶体直径较小,晶体结构形态变模糊,结晶度由68.0%下降为45.7%,熔点由115.23℃下降为92.40℃。90d后SE薄膜的质量损失率达到63%,珚Mw由34700降为11500,而PBS质量损失率为27%,珚Mw由49000降为33000。表明癸二酸的引入降低了PBS的结晶性能,提高了其降解性能。     

Bioresorbable and bioactive polymer/Bioglass® composites with tailored pore structure for tissue engineering applications

An overview about the development of porous bioresorbable composite materials for applications as scaffolds in tissue engineering is presented. A thermally induced phase separation method was developed to fabricate porous foam-like structures of poly(lactide-co-glycolide) (PLGA) containing bioactive glass particle additions (up to 50 wt.%) and exhibiting well-defined, oriented and interconnected porosity. The in vitro bioactivity and the degradability of the composite foams were investigated in contact with phosphate buffer saline (PBS). Weight loss, water absorption and molecular weight measurements were used to monitor the polymer degradation after incubation periods of up to 7 weeks in PBS. It was found that the presence of bioactive glass retards the polymer degradation rate for the time period investigated. The present results show a way of controlling the in vitro degradation behaviour of PLGA porous composite scaffolds by tailoring the concentration of bioactive glass.     

酪氨酸改性聚乳酸共聚物的合成及降解研究

以乳酸(D,L-LA)和L-酪氨酸(Tyr)为原料[n(D,L-LA)/n(Tyr)=95/5],氯化亚锡(Sn(cl)2)为催化剂,采用梯度升温法,通过直接熔融缩聚合成聚(乳酸-酪氨酸)共聚物(PLA-co-Tyr).用特性粘度测试、FT-IR、1 H-NMR、GPC、DSC、XRD、TG等对其进行表征,通过SEM、XRD等方法研究了降解前后材料的表面形态、结晶度及失重率的变化.结果表明:系列共聚物中的重均相对分子量Mw最大可达2900,与聚乳酸相比具有较小的Tg和结晶度,分解温度高于180℃,具有良好热稳定性且降解性能优于聚乳酸.     

磷酸镁/PBS/小麦蛋白复合骨修复材料

采用共沉淀法合成磷酸镁, 将磷酸镁(MP)、聚丁二酸丁二醇酯(PBS)和小麦蛋白(WP)进行复合, 制备出MP/PBS/WP复合骨修复材料。通过体外降解、生物活性以及细胞培养等实验对复合材料的理化性能及细胞相容性进行了研究。结果显示: MP/PBS/WP复合材料在Tris-HCl缓冲液中浸泡10 d后, 溶液pH从7.4上升至7.51, 浸泡12 w后, 其降解率达到58.43wt%; 复合材料在模拟体液中浸泡10 d后, 其表面形成磷灰石层; 复合材料能促进MC3T3-E1细胞的增殖与分化。结果表明: MP/PBS/WP复合材料具有优良的降解性、生物活性和细胞相容性, 有望成为一种新型骨修复材料。     

Investigation on the properties of linear PLA-poloxamer and star PLA-poloxamine copolymers for temporary biomedical applications

The objective of this work was to develop and study new biodegradable thermoplastics with improved mechanical properties for potential use as temporary implantable biomaterials. Linear poloxamer and star-shaped poloxamine have been used as macroinitiators for the ring-opening polymerization (ROP) of lactide to yield high molecular weight PLA-based thermoplastic block copolymers. The influence of the nature of the macroinitiator, PLA crystallinity and initial molecular weight on the copolymers properties was investigated by performing a 7-week degradation test in PBS. The evaluation of water uptakes and molecular weights during the degradation pointed out an early hydrolytic degradation of the 100-kg?mol^? 1 copolymers compared to the 200-kg?mol^? 1 ones (molecular weight decrease of ca. 40% and 20%, respectively). A dramatic loss of tensile mechanical properties was also observed for the 100-kg?mol^? 1 copolymers, whereas the 200-kg?mol^? 1 copolymers showed stable or even slightly improved properties with Young's moduli around 500 MPa and yield strains around 3% to 4%. Finally, the cytocompatibility of the more stable 200 kg?mol^? 1 copolymers was confirmed by murine mesenchymal stem cells (MSCs) culture.     

不同成膜工艺对PCL结晶及微生物降解性能的影响

将压延成膜和溶剂成膜制备的聚ε-己内酯(PCL)膜放入降解液进行100d的生物降解,以研究不同成膜工艺对PCL降解性和降解前后结晶的影响。采用显微镜观察降解前后薄膜表面形态变化;通过广角X射线衍射法(WAXD)表征其降解前后结晶变化;利用凝胶渗透色谱(GPC)测定降解过程中PCL相对分子质量和分子量分布的变化。研究结果表明,溶剂成膜工艺可提高PCL亲水性,增大结晶尺寸,提高PCL降解性;而压延成膜工艺使膜表面致密,结晶尺寸减小,但对结晶形态和结晶度影响不大,降解后PCL晶形均未发生大的变化,结晶度有所下降。     

A study on the rate of degradation of the bioabsorbable polymer polyglycolic acid (PGA)

As part of a study to characterise bioabsorbable scaffolds for tissue engineering an investigation has been conducted into the rate of degradation of polyglycolic acid (PGA). This is one of the most commonly used bioabsorbable materials and has been used in sutures since the 60s and more recently in cell scaffolds, drug delivery devices and bone fixation pins. This study looks at the influence that surface-to-volume ratio i.e. thickness of material, has on degradation. By degrading various thicknesses of PGA in a buffer saline solution over 24 days and testing their properties at regular intervals, a knowledge of how surface-to-volume ratio affects degradation was developed. Properties such as weight loss, crystallinity, molecular weight and structural integrity were measured. Results showed that rate of mass loss was dependent on sample thickness but crystallinity, melting point and molecular weight were independent of thickness.     

Comparison of the degradability of poly(lactide) packages in composting and ambient exposure conditions

The adoption of biodegradable polymeric materials is increasing in food and consumer goods packaging applications, due to concerns about the disposal of petroleum‐based polymers and the increasing cost of petroleum‐based polymer resins. Currently, poly(lactide) (PLA) polymers are the biggest commercially available bio‐based polymeric packaging materials. As the main motivation for adopting biopolymers is environmental, there is a need to address the degradability and environmental performance of biodegradable packages. The aim of this study was to investigate and compare the degradation of two commercially available biodegradable packages made of PLA under real compost conditions and under ambient exposure, using visual inspection, gel permeation chromatography, differential scanning calorimetry and thermal gravimetric analysis. A novel technique to study and track the degradability of these packages under real compost conditions was used. Both packages were subjected to composting and ambient exposure conditions for 30 days, and the degradation of the physical properties was measured at 1, 2, 4, 6, 9, 15 and 30 days. PLA bottles made of 96% l ‐lactide exhibited lower degradation than PLA delicatessen (‘deli’) containers made of 94% l ‐lactide, mainly due to their highly ordered structure and, therefore, their higher crystallinity. The degradation rate changed as the initial crystallinity and the l ‐lactide content of the packages varied. Temperature, relative humidity and pH of the compost pile played an important role in the rate of degradation of the packages. First‐order degradation kinetics and linear degradation trends were observed for both packages subjected to composting conditions. Copyright © 2006 John Wiley & Sons, Ltd.     

Biodegradation of hydrophilic–hydrophobic hydrogels and its effect on albumin release

The objective of this study was to examine the effects of composition ratio of a new class of bicomponent biodegradable hydrogels and the molecular weights of the constituents on the hydrolytic degradability of the hydrogels and their release of bovine serum albumin (BSA). Biodegradable hydrogels were prepared from dextran derivative of allyl isocyanate (dex-AI) and poly (D,L) lactide diacrylate macromer (PDLLAM) over a wide range of dex-AI to PDLLAM composition ratio. The results obtained indicated that the hydrolytic degradation of these biodegradable hydrogels could be controlled by adjusting the composition ratio of dex-AI to PDLLAM or by changing their molecular weights. Along with the hydrogel degradation, water content of the hydrogels changed, and 3D porous network structure was observed. Generally, as the PDLLAM composition in the hydrogels increased, the rate of weight loss increased due to the hydrolytic degradation of the PDLLAM. The increase in molecular weights of either dex-AI or PDLLAM would decrease the degradation rate of the dex-AI/PDLLAM hydrogels. BSA release data correlated well with the hydrogel degradation profiles, suggesting that the extent and rate of BSA release would be mainly controled by hydrogel degradation. As the PDLLAM composition in the hydrogel increased, the extent and rate of BSA release also increased. An increase in the molecular weights of the hydrogel constituents, however, led to a decrease in BSA release.