聚[(双-甘氨酸乙酯)膦腈]/聚酯共混相容性研究

采用溶液混合法制备了聚[(双－甘氨酸乙酯）膦腈]（PGP）与丙交酯均聚物（PLA）或丙交酯／乙交酯共聚物（PLGA）的共混体系，利用示差扫描量热仪、傅里叶红外光谱仪和相差显微镜研究了两体系的共混相容性。实验结果表明，PGP与PLA不相容，但通过氢键相互作用可与PLGA达到部分相容，且PGP／PLGA的共混相容性随着PLGA含量的增加而有所改善。     

生物相容性嵌段型聚电解质胶束在水溶液中的酶降解行为

采用激光光散射仪和原子力显微镜研究了生物相容性嵌段型聚电解质聚左旋乳酸-b-聚甲基丙烯酸二甲氨基乙酯(PLLA-b-PDMAEMA)胶束在水溶液中2个温度(室温25.0℃和人体温度36.8℃)和2个pH值(肿瘤pH=4.9和正常组织pH=7.4)条件下的酶降解行为. 酶降解过程中存在一个失活时间, 在此之前, 胶束的酶降解遵循逐个降解机理. 失活时间之后, 出现裂纹或是通道的胶束核为降低其在溶剂中的表面积, 从而降低体系自由能, 胶束之间发生了聚集. 升高温度后, 酶的活性提高, 初始降解速率加快. 由于pH=4.9时胶束壳层因静电斥力作用而较为伸展, 使得胶束降解更快.     

聚(L-谷氨酸)水凝胶的Diels-Alder制备及其生物分子响应性研究

报道了一种含有二硫键的聚L-氨基酸共价交联网络,制备了能对含巯基生物分子与蛋白酶产生响应的新型聚L-氨基酸水凝胶.通过二硫键将降冰片烯基团键合在聚(L-谷氨酸)侧链,所得到的聚合物与末端修饰四嗪基团的四臂聚乙二醇在水溶液中混合,通过降冰片烯与四嗪基团之间发生Diels-Alder反应形成分子间共价交联,获得了聚(L-谷氨酸)/聚乙二醇水凝胶.研究了水凝胶在含巯基生物活性分子谷胱甘肽(GSH)作用下的性质变化.结果表明,2种官能化聚合物混合后可快速形成稳定的水凝胶,其力学性质随聚合物浓度、2种聚合物比例和降冰片烯基团的取代度的改变而变化.体外降解实验结果表明,在GSH或弹性蛋白酶存在的条件下,水凝胶的降解速率显著增加.同时,经GSH处理的水凝胶机械强度也显著降低.大鼠体内实验表明,在交联点引入GSH响应性的二硫键会明显加速聚氨基酸水凝胶的体内降解.进一步体外细胞实验与组织学分析结果表明,所获得聚氨基酸/聚乙二醇水凝胶具有良好的体外细胞相容性和动物体内组织相容性.     

聚乙烯/聚己内酯-聚乙二醇共聚物共混物组分相容性及其光水双降解的研究

用动态力学振簧仪、DSC、FT IR、光辐照、浸水降解法研究了马来酸酐化线型低密度聚乙烯 (MPE) /聚己内酯 聚乙二醇共聚物 (PCE)共混物的组分相容性、晶区的熔化和结晶行为以及降解特性 .结果表明 ,马来酸酐化是发生在LLDPE短支链的甲基末端上并通过马来酸酐与PCE的羟基形成氢键相互作用 ,使两组分存在部分相容性 ,PCE的主转变与MPE支链的 β转变发生内移现象 .在共混物中加入乙烯 丙烯酸共聚物(EAA)可以起增容作用 ,同时使MPE和PCE组分的熔点和熔化热进一步下降 .对不同含量PCE的MPE/PCE/EAA共混物的降解特性的研究表明 ,PCE的加入使体系发生光、水降解 ,且随PCE含量的增加降解速度加快 .光 水联合作用的降解速度比单一光或水降解更快 .     

聚三亚甲基碳酸酯的生物相容性研究

以实验室自制的聚三亚甲基碳酸酯(PTMC)为研究对象,通过测定聚三亚甲基碳酸酯在体外酶解过程中降解液pH变化,考察其在降解过程中是否产生酸性降解产物;通过MTS法考察聚三亚甲基碳酸酯的体外细胞毒性;通过HE染色的方法考察聚三亚甲基碳酸酯在大鼠体内埋植部位的皮肤刺激性,进而考察聚三亚甲基碳酸酯的生物相容性。结果表明:PTMC在降解过程中不产生酸性降解产物,可避免埋植部位无菌炎症的产生。同时不同分子量的PTMC可以存在于皮下组织而不会造成伤害,因此聚三亚甲基碳酸酯具有良好的生物相容性,可安全植入体内。     

聚磷酸钙骨支架材料的可控降解性和细胞毒性研究

采用重力二次烧结法制备了聚磷酸钙(CPP)骨支架材料,并对材料的体外可控降解性和细胞毒性进行了研究。实验结果表明,CPP呈线性链状结构,具有无定形态、γ-CPP和β-CPP 3种结构。晶相对CPP的降解速率影响明显,无定形CPP降解最快,10 d完全降解;β-CPP降解最慢,30 d约失重11％。同时,材料的降解速率随烧料粒径的增大而加快。细胞在材料表面粘附铺展且增殖良好。制备的CPP骨支架材料具有优良的可控降解性和生物相容性,可用于修复骨组织缺损和作为支架材料用于组织工程。     

因子分析法和FTIR光谱法研究聚甲基丙烯酸正十八酯和聚醋酸乙烯酯的共混

聚甲基丙烯酸正十八酯[P(n-OMA)]是梳状聚合物,玻璃化温度很低(173K),与其他聚合物共混的热行为的研究需在液氮下进行.本文应用Koenig的因子分析法和FTIR光谱法,在常温下判别了P(n-OMA)与聚醋酸乙烯酯(PVA)的共混相容性,用分峰技术准确定量了它们的相互作用,讨论了影响相互作用的因素。并用DTA谱验证了所得的结论.     

高分子量聚对二氧环己酮改进聚DL-乳酸柔韧性的研究

为了提高DL-聚乳酸(PDLLA)的柔韧性,将10～20wt%不同比例的由本课题组自主合成的高分子量聚对二氧环己酮(PPDO)加入到PDLLA基体中,对共混物的微观两相形态、力学性能、热学性能和表面性质、降解性能等物化性质进行了研究.实验结果表明,PPDO加入后,在PDLLA/PPDO共混物的柔韧性得到显著提高的同时,共混物表面亲水性相应提高,降解速率也随之加快.     

聚α烯烃光催化降解的机理研究

采用光催化微反应器对铜箔表面附着的聚α烯烃进行了光催化降解处理,利用X射线光电子能谱(XPS)、电子自旋共振谱(ESR)和傅里叶变换红外光谱(FTIR)等对光催化降解前后聚α烯烃的元素化学状态、自由基和官能团进行了检测,并探讨了光催化降解机理.结果表明,聚α烯烃光催化降解过程中发生了含氧基团的引入和CO_2脱附;参加降解反应的自由基主要为羟基自由基·OH,降解过程中—OH逐渐增多、C—H键逐渐减少;聚α烯烃光催化降解过程中,·OH进攻聚α烯烃是从取代反应开始的,首先取代的是末端的氢原子,然后是末端羟基向醛基和羧基的转变,最后是碳链断裂形成小分子有机物,这一过程持续进行,最终生成CO_2和H_2O等无机物.     

末端带有磷酰胆碱基团的聚丁二酸丁二醇酯的合成、表征和性能研究

采用四步反应合成了一种新的具有良好生物相容性和生物降解性的末端带有磷酰胆碱(PC)基团的聚丁二酸丁二醇酯PBS-PC. 采用1H NMR、IR、凝胶色谱(GPC)和X射线光电子能谱(XPS)表征了聚合物的结构. 同时研究了聚合物的亲疏水性能、体外降解、溶胀率和对模型药物中性红的缓释性能. 结果显示: PC基团引入, 在一定程度上提高了PBS的亲水性、降解速率、溶胀率和对中性红的缓释性能.     

Blends of polycarbonate and ethylene-1-octylene copolymer

The mechanical properties and morphology of polycarbonate/ethylene-1-octylene copolymer (PC/POE) binary blends and PC/POE/ionomer ternary blends were investigated. The tensile strength and elongation at break of the PC/POE blends decreased with increasing the POE content. The impact strength of the PC/POE blends showed less dependence on thickness than that of PC. And the low-temperature impact strength of PC was modified effectively by addition of POE. The morphology of the PC/POE blends was observed by scanning electron microscope. The PC/POE weight ratio had a great effect on the morphology of the PC/POE blends. For the PC/POE (80/20)/ionomer ternary blends, low content (0.25 and 0.5 phr) of ionomer could increase the tensile properties of PC/POE (80/20) blend and had little effect on the impact strength. And 0.5 phr ionomer made the dispersed domain distribute more uniformly and finely than the blend without it. But with high content of ionomer, the degradation of PC made the mechanical properties of the blends deteriorate. Blending PC and ionomer proved the degradation of PC, and the molecular weight decreased with increasing the ionomer content.     

Properties of immiscible and ethylene-butyl acrylate-glycidyl methacrylate terpolymer compatibilized poly (lactic acid) and polypropylene blends

Poly(lactic acid) (PLA) and polypropylene (PP) blends of various proportions were prepared by melt-compounding. The miscibility, phase morphology, thermal behavior, and mechanical and rheological properties of the blends were investigated. The blends were immiscible systems with two typical morphologies, spherical droplet and co-continuous, and could be obtained at various compositions. Complex viscosity, storage modulus and loss modulus depend on the PP content. Thermal degradation of all blends led to two weight losses, for PLA and PP. The incorporation of PP improved the thermal stability of the blend. The effect of compatibilizer (ethylene-butyl acrylate-glycidyl methacrylate terpolymer, EBA-GMA) on the morphology and mechanical properties of 70/30 w/w PLA/PP blends was investigated. The tensile strength of these blends reached a maximum for 2.5 wt% EBA-GMA, and impact strength increased with increasing EBA-GMA content, suggesting that EBA-GMA is an effective compatibilizer for PLA/PP blends.     

Thermal degradation of poly(vinyl chloride)/poly(ethylene oxide) blends: Thermogravimetric analysis

Thermal stability of poly(vinyl chloride)/poly(ethylene oxide) (PVC/PEO) blends has been investigated by thermogravimetric analysis (TGA) in dynamic and isothermal heating regime. PVC/PEO blends were prepared by hot-melt extrusion (HME). According to TG analysis, PEO decomposes in one stage, while PVC and PVC/PEO blends in two degradation stages. In order to evaluate the effect of PEO content on the thermal stability of PVC/PEO blends, different criteria were used. It was found that thermal stability of PVC/PEO blends depends on the blend composition. The interactions of blends components with their degradation products were confirmed. By using multiple heating rate kinetics the activation energies of the PVC/PEO blends thermal degradation were calculated by isoconversional integral Flynn–Wall–Ozawa and differential Friedman method. According to dependence of activation energy on degree of conversion the complexity of degradation processes was determined.     

Mechanical, thermal and degradation properties of poly(d,l-lactide)/poly(hydroxybutyrate-co-hydroxyvalerate)/poly(ethylene glycol) blend

The mechanical, thermal and biodegradable properties of poly(d,l-lactide) (PDLLA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ethylene glycol) (PEG) blends were studied. The influence of PEG on the tensile and impact strengths of the blends was investigated. The results showed that the toughness and elongation at break of the PDLLA/PHBV (70/30) blends were greatly improved by the addition of PEG, and the notched Izod impact strength increased about 400% and the elongation at break increased from 2.1% to 237.0%. The thermal and degradation properties of the blends were investigated by differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA), it was found that the thermal stability of PHBV in the presence of PDLLA was improved. The degradation test showed that the addition of PEG could notably accelerate the biodegradation of the blends in the soil at room temperature, and the mass loss is about 20% after 30 days of the storage.     

Thermal properties and degradability of poly(propylene carbonate)/poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PPC/PHBV) blends

Poly(propylene carbonate)/poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PPC/PHBV) blends were prepared via the solution casting method at different proportions. Their thermal characteristics were studied by means of differential scanning calorimetry (DSC) and thermogravimetry (TG). The degradability of the blends was investigated in soil suspension cultivation and in vitro degradation testing. The changes of structure and molecular weight for blends were also studied by ¹H nuclear magnetic resonance spectroscopy (¹H NMR), scanning electron microscopy (SEM) and gel permeation chromatography (GPC) before and after degradation. Although the PPC/PHBV blends were immiscible, the addition of PHBV could improve the thermal stability of PPC. PHBV was degraded mainly by the action of microbial enzymes in the soil suspension, which biodegraded it more rapidly than PPC in a natural environment. PPC was degraded mainly by chemical hydrolysis and random hydrolytic scission of chains in the PBS solution in vitro, and degradation of PPC was more rapid than that of PHBV in a simulated physiological environment.     

氟橡胶/改性乙丙橡胶并用胶的热稳定性

采用热分析技术考察了氟橡胶及氟橡胶(FPM)/改性乙丙橡胶(MEPDM)并用胶在氮气中的热稳定性, 通过微分法与积分法两种动力学方法计算出了FPM及FPM/MEPDM并用胶的热分解活化能E和指前因子A. 结果表明, 并用胶的热分解温度稍高于纯的氟橡胶, 但热分解活化能略低于氟橡胶, FPM、FPM/MEPDM(5%)和FPM/MEPDM(10%)的热分解活化能分别为251.74、244.98和219.60 kJ·mol-1; 热分解反应级数n均为0.95. 随着失重百分率的增大, 热分解活化能增大.     

Isothermal Degradation of PVC/MBS Blends

The process of thermal degradation of poly(vinyl chloride)/poly(methyl methacrylate-butadiene-styrene) (PVC/MBS) blends was investigated by means of isothermal thermogravimetry in nitrogen. The total mass loss was determined after 120 min. The kinetic parameters of the degradation process were determined by applying two kinetic models: the model which assumes autocatalytic degradation (Prout-Tompkins) and the model of two-dimensional diffusion. It was established that the thermal degradation at lower degrees of conversion (α<0.20) was well described by the former model, but the latter model was applicable at higher degrees of conversion. The thermal stability of blends at a certain temperature of isothermal degradation depends on the blend composition and the shell/core ratio in MBS, and on the adhesion in the boundary layer in PVC/MBS blends. This revised version was published online in July 2006 with corrections to the Cover Date.     

Aging behavior and thermal degradation of fluoroelastomer reactive blends with poly-phenol hydroxy EPDM

In this paper, the aging behavior of the reactive blends of fluoroelastomer (FPM) with poly-phenol hydroxy ethylene propylene diene monomer rubber (PHEPDM) in hot air was firstly investigated. The aging mechanism was analyzed by the swelling experiment, attenuated total-reflectance Fourier-transform infrared (FTIR-ATR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that the aging process increased the crosslinking density and the content of double bond. The O/F or O/C ratios increased and then decreased during aging because of the oxidation reaction of molecular chain and the surface migration of fluoro group. Secondly, thermogravimetric analysis (TGA) was used to study the thermal degradation behavior of the reactive blends. The apparent degradation activation energy (E) of FPM/PHEPDM reactive blends was calculated by the Kissinger and Coats-Redfern methods, respectively. The results showed that the FPM/PHEPDM reactive blends had higher thermal degradation temperature but lower E than FPM. Both the thermal degradation process of FPM/PHEPDM reactive blends and FPM were determined by nucleation and growth mechanism (Am). The general mechanism function was [−ln(1 − α)]^1/m. The optimum value of m was between 1/3 and 1/2 for FPM/PHEPDM reactive blends, but 1/2 for FPM. From the results above, it was deduced that the special structure of PHEPDM made itself surrounded by fluoroelastomer and protected from hot-air aging and thermal degradation.     

Thermal degradation and crystallisation studies of reactively compatibilised polymer blends

The thermal degradation and crystallisation behaviours of polyamide12/isotactic polypropylene (PA12/PP) blends were studied. Effects of blend ratio and compatibiliser concentration on the thermal degradation properties of the blends were analysed. The activation energy for degradation in compatibilised and uncompatibilised blends computed using Horowitz-Metzger equation was reported. The blend ratio as well as the presence of compatibiliser has significant effect on the thermal stability of the blends. Phase morphology was found to be one of the decisive factors that affected the thermal stability of both uncompatibilised and compatibilised blends. Melting and crystallisation behaviours of the blends in the presence and absence of compatibiliser were evaluated. It was observed that blending has no significant effect on the melting and crystallisation properties of PA12 and PP. Compatibilisation of 70/30 and 50/50 PA12/PP blends didn't affect the crystallisation and melting behaviours of PA12 and PP even though some discrepancies were observed.