Tough blends of polylactide and castor oil

Poly(l-lactide) (PLLA) is a renewable resource polymer derived from plant sugars with several commercial applications. Broader implementation of the material is limited due to its inherent brittleness. We show that the addition of 5 wt % castor oil to PLLA significantly enhances the overall tensile toughness with minimal reductions in the modulus and no plasticization of the PLLA matrix. In addition, we used poly(ricinoleic acid)-PLLA diblock copolymers, synthesized entirely from renewable resources, as compatibilizers for the PLLA/castor oil blends. Ricinoleic acid, the majority fatty acid comprising castor oil, was polymerized through a lipase-catalyzed condensation reaction. The resulting polymers contained a hydroxyl end-group that was subsequently used to initiate the ring-opening polymerization of l-lactide. The binary PLLA/castor oil blend exhibited a tensile toughness seven times greater than neat PLLA. The addition of block copolymer allowed for control over the morphology of the blends, and even further improvement in the tensile toughness was realized-an order of magnitude larger than that of neat PLLA.     

蓖麻油基聚氨酯的制备及其性能研究

采用可再生的蓖麻油、甘油、TDI为原料,合成出端-NCO的蓖麻油基聚氨酯(PU)预聚体.对预聚体中NCO的含量进行了测定,并采用FT-IR对材料进行了定性分析;采用TG对蓖麻油基PU膜的热性能进行分析,并对固化后的材料力学性能进行了测试.结果表明:蓖麻油基PU预聚体的NCO含量在5.25%～4.93%时,体系在-18～40 ℃能固化成膜,且成膜物具有较好热学性能和力学性能.     

Preparation,damping and thermal properties of potassium titanate whiskers filled castor oil-based polyurethane/epoxy interpenetrating polymer network composites

A series of potassium titanate whiskers (PTW) filled castor oil-based polyurethane (PU)/epoxy resin (EP) interpenetrating polymer network (IPN) composites were prepared. The damping properties, thermal stability as well as tensile strength of the IPN composites were studied systematically in terms of composition. Results revealed that the addition of PTW can significantly improve the damping properties of pure PU/EP IPN and can improve the thermal decomposition temperature. Tensile tests showed that the tensile strength of the IPN composites was improved after the incorporation of PTW. It is expected that the PTW filled IPN composites may be used as structural damping materials.     

热塑性聚氨酯/聚乙烯醇共混材料制备及性能

通过溶液共混的办法,制备了热塑性聚氨酯(TPU)/聚乙烯醇(PVA)共混材料。通过FI-IR、DMTA初步考查了两相的相互作用;同时对共混材料的水溶胀性能进行了表征。结果表明, TPU/PVA两相存在氢键作用,具有一定的相容性;共混材料吸水率随着PVA的加入而逐渐增大,两相配比为7:3时,共混材料力学性能最佳。     

Structure and properties of polylactide/natural rubber blends

Polylactide, PLA, is a biodegradable thermoplastic polyester derived from biomass that has restricted packaging applications due to its high brittleness and poor crystallisation behaviour. Here, new formulations based on natural rubber–PLA blends have been developed. The processing windows, temperature, time, and rotor rate, and the rubber content have been optimised in order to obtain a blend with useful properties. The rubber phase was uniformly dispersed in the continuous PLA matrix with a droplet size range from 1.1 to 2.0 μm. The ductility of PLA has been significantly improved by blending with natural rubber, NR. The elongation at break improved from 5% for neat PLA to 200% by adding 10 wt% NR. In addition, the incorporation of NR not only increased the crystallisation rate but also enhanced the crystallisation ability of PLA. These materials are, therefore, very promising for industrial applications.     

蓖麻油-聚醚基聚氨酯弹性体的制备和表征

以可再生资源-蓖麻油作为起始荆,环氧丙烷开环聚合制备了不同分子量的蓖麻油-聚醚多元醇,并通过1HNMR 和 FTIR 等手段来分析蓖麻油-聚醚多元醇的结构.以不同分子量的蓖麻油-聚醚多元醇作为原料制备了一系列聚氨酯弹性体,并对其进行物理机械性能和热性能分析.研究结果表明:随着蓖麻油聚醚多元醇分子量的增加,其聚氨酯弹性体的扯断伸长率逐渐增加,拉伸强度、撕裂强度和硬度逐渐降低;同时,热稳定性提高,硬段的结晶熔融温度和结晶度降低.     

Effects of organic chain length of layered zirconium phosphonate on the structure and properties of castor oil-based polyurethane nanocomposites

Three novel organic–inorganic hybrid molecules, layered zirconium phosphates or phosphonates, were synthesized. To study the effects of organic chain length of them on the structure and properties of polymer nanocomposites, the polyurethane/α-zirconium phosphate (PU/ZrP), polyurethane/zirconium 2-aminoethylphosphonate (PU/ZrAEP) and polyurethane/zirconium 2-(2-(2-(2-aminoethylamino)ethylamino)ethylamino) ethylphosphonate (PU/Zr(AE)₄P) nanocomposites were prepared, and characterized by Fourier Transform Infrared (FT-IR) spectroscopy, wide-angle X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and tensile testing. It was revealed that morphological, mechanical, and thermal properties of these nanocomposites were strongly dependent on the organic chain length of the layered zirconium phosphonates. The results showed that the fillers with longer chain length exhibited better dispersion in the PU matrix. As expected, the mechanical properties and water resistance were improved with the increasing of organic chain length of fillers, which attributed to better interfacial adhesion between fillers and PU matrix.     

蓖麻油多元醇在聚氨酯硬泡中的应用研究

以可再生的蓖麻油为主要原料,与甘油进行酯交换反应制备蓖麻油多元醇,通过红外光谱和分子量分布,分别考察了蓖麻油/甘油不同配比、不同温度和不同反应时间下的醇解产物性质。结果证明,在一定的催化条件下,200℃下反应3h蓖麻油多元醇羟值最高达434mgKOH/g,同时蓖麻油反应转化率最高。将此蓖麻油多元醇应用于聚氨酯硬泡中,显示出较好的泡沫性能。     

Stability and mechanical evaluation of bovine pericardium cross-linked with polyurethane prepolymer in aqueous medium

The present study investigates the potential use of non-catalyzed water-soluble blocked polyurethane prepolymer (PUP) as a bifunctional cross-linker for collagenous scaffolds. The effect of concentration (5, 10, 15 and 20%), time (4, 6, 12 and 24 h), medium volume (50, 100, 200 and 300%) and pH (7.4, 8.2, 9 and 10) over stability, microstructure and tensile mechanical behavior of acellular pericardial matrix was studied. The cross-linking index increased up to 81% while the denaturation temperature increased up to 12 °C after PUP crosslinking. PUP-treated scaffold resisted the collagenase degradation (0.167 ± 0.14 mmol/g of liberated amine groups vs. 598 ± 60 mmol/g for non-cross-linked matrix). The collagen fiber network was coated with PUP while viscoelastic properties were altered after cross-linking. The treatment of the pericardial scaffold with PUP allows (i) different densities of cross-linking depending of the process parameters and (ii) tensile properties similar to glutaraldehyde method.     

天然石墨-纳米银/聚氨酯导电复合薄膜的制备及性能

采用热处理还原银盐原位引入银粒子的方法, 成功制备了天然石墨-纳米银/聚氨酯(C-Ag/PU)导电复合薄膜。并通过透射电镜(TEM)、 扫描电镜(SEM)观察了该复合薄膜的微观结构, 用X射线衍射仪(XRD)跟踪了银的还原和银粒子的生长过程, 探讨了加热温度和加热时间对银还原过程的影响, 研究了纳米银的生成和聚集对C/PU复合体系导电性能的影响。结果表明, 随着热处理的进行, 银粒子不断地生成和聚集, 最终以纳米尺寸(约10nm)均匀分散在聚合物基体中。纳米银粒子在天然石墨粒子之间起到了桥梁的作用, 改善了复合体系的导电通路, 显著提高了复合体系的导电性。      

Preparation and evaluation of insulin-loaded polylactide microspheres using factorial design

The aim of this work was to study the influence of the concentration and molecular weight of poly(DL-lactide) (PLA) on the characteristics and in vivo biological activity of protein-loaded microspheres. At the same time, an attempt was made to achieve further optimization of the formulation. In the study, insulin was chosen as a model of protein drugs. Nine formulations of injectable insulin-loaded PLA microspheres were prepared using an emulsification and solvent evaporation process according to a factorial design. The trapping efficiency, drug loading, and the drop percentages of blood glucose levels at 24 hr and 72 hr in mice were used to evaluate the formulations. The results showed that PLA molecular weight and, especially, PLA concentration exerted influences on the characteristics and in vivo biological activity of insulin-loaded microspheres. The drug-trapping efficiency increased with the increase of the polymer concentration. The drug loading decreased with the increase of the polymer concentration and was not obviously affected by PLA molecular weight. The drop percentage of blood glucose level at 24 hr increased with the increase of polymer concentration and molecular weight. At 72 hr, the drop percentages of blood glucose levels were slightly increased with the increase of PLA concentration and then significantly decreased after the PLA concentration was above 150 mg/ml. An optimized formulation was prepared with PLA-10k at a concentration of 200 mg/ml. The experimental values of the response variables were close to the predicted values. The results suggest that the in vivo release behavior should be taken into consideration in the design of protein-loaded PLA microspheres.     

Preparation,characterization and mechanical properties of the polylactide/perlite and the polylactide/montmorillonite composites

In this study polylactide (PLA)/perlite and PLA/montmorillonite (MMT) composites were prepared by melt extrusion and solvent dissolution methods. The effects of organic/inorganic ratios and the kind of inorganic compounds on the characterization of the composite materials were investigated. The thermal stability of the organic–inorganic composite materials was evaluated by TGA and DSC, and the morphology of these composites was measured as SEM images. The modulus of elasticity was evaluated by Dynamic mechanical analysis (DMA). The PLA/inorganic composites exhibited remarkable improvement of mechanical and thermal properties when compared with those of the pure PLA.     

八氨苯基POSS交联改性聚氨酯弹性体的制备与性能

以八氨苯基多面体低聚倍半硅氧烷(OapPOSS)为交链剂,原位合成了含有POSS结构的聚氨酯弹性体纳米复合材料,分别采用FT-IR、光学显微镜,动态热机械(DMA)分析以及热重分析(TGA)等对所合成的复合材料进行了表征。结果表明:随着OapPOSS用量的增加,所制POSS/PUE复合材料的拉伸强度增加,扯断伸长率下降,储能模量增加,阻尼因子下降,玻璃化转变温度升高,热分解速率降低。     

聚乳酸/蒙脱石纳米复合材料的制备与表征

对纳基蒙脱石(MMT)有机改性后,采用溶液插层薄膜塑造工艺制备蒙脱石/聚乳酸(PLA)纳米复合物,采用X-Ray粉晶衍射(XRD)、综合热分析(TGA&DSC)、红外吸收光谱(IR)等方法对复合材料进行表征,讨论了蒙脱石对插层结果的影响.结果表明,PLA能够插入MMT层间;MMT的层间距由1.40nm增大到2.16nm;复合材料的热稳定性能得到改善.     

壳聚糖/聚乳酸/聚羟基丁酸酯人工硬脑膜的制备与性能研究

以壳聚糖、聚乳酸、聚(R)-3-羟基丁酸甲酯等为主要成膜物质,用流延法制得新型薄膜材料。研究表明,当壳聚糖∶明胶∶聚乳酸为1∶1∶1时,得到膜的抗拉强度比其他的可生物降解膜都大,达到27.346MPa;当壳聚糖∶明胶∶聚(R)-3-羟基丁酸甲酯为1∶1∶1时,其抗拉强度达到24.363Mpa,防漏性能达到80h。经模拟体内降解研究,在人工脑脊液的环境中浸置44d后,降解率分别为20%左右,降解速度较慢,可以保持其结构6～7周,有利于引导组织再生材料的基本要求。因此该复合膜有望成为医用可生物降解人工硬脑膜。     

纳米纤维素-碳纳米管/热塑性聚氨酯复合薄膜的制备及应变响应性能

采用2,2,6,6?四甲基哌啶?1?氧自由基(TEMPO)氧化法制备了不同羧基含量的纳米纤维素(CNF),并将其用作碳纳米管(CNTs)的分散剂,通过超声、离心处理制备出稳定均一的CNF?CNTs分散液,然后通过朗伯?比尔定律测定CNF?CNTs分散液中CNTs的浓度,研究了不同CNF羧基含量对CNTs的分散效果。此外,利用静电纺丝法制备出柔性、多孔的热塑性聚氨酯(TPU)薄膜作为基体,以CNF?CNTs分散液作为导电填料,通过真空抽滤法将CNF?CNTs负载于TPU多孔膜上,制备出CNF?CNTs/TPU复合薄膜,并探究了不同CNF羧基含量对CNF?CNTs/TPU复合薄膜应变响应性能的影响规律。结果表明,羧基含量对CNF的分散性能具有重要影响。随着CNF羧基含量的提高,CNF对CNTs分散效果越好,CNF?CNTs/TPU复合薄膜具有更大的应变响应范围。当CNF羧基含量为1.698 mmol/g时,CNF?CNTs/TPU复合薄膜的应变响应范围高达507%,灵敏度系数为335,表现出优异的应变响应性能。      

纳米TiO2/聚乳酸复合材料的制备和表征

采用原位聚合的方法制备了有机化处理过的纳米 TiO 2粒子质量分数分别为 1 wt %、3 wt %、5 wt %和10 wt %的 4种纳米 TiO 2/聚乳酸复合材料。SEM结果表明 , 当纳米 TiO 2粒子质量分数较低时 , 纳米 TiO 2在聚乳酸基体中呈现均匀稳定分散 , 而质量分数较高时则发生团聚。通过力学和热学等性能测试发现复合材料的最大热分解温度、 玻璃化转变温度和力学性能相对于聚乳酸有较大幅度提高 , 其中纳米 TiO 2的质量分数为 3 wt %时改善效果最明显 , 其最大热分解温度、 玻璃化转变温度分别比聚乳酸提高了 25. 3℃和 4. 9℃, 拉伸强度、 断裂伸长率和弹性模量分别提高了 83. 6 %、 6. 73 %和 129. 4 %。     

微量水对聚氨酯预聚体结构与溶解性的影响研究

为了更充分地了解微量水对聚氨酯预聚反应及预聚体结构的影响,用一步法首先合成了聚氨酯初始预聚体,然后研究了微量水及扩链温度等对聚氨酯预聚体的特性粘数、在THF中的溶解性和分子量分布等的影响,采用FT-IR对水扩链预聚体的聚集态结构进行了初步的研究。研究结果表明,水和—NCO基团反应生成聚脲结构,表现在聚氨酯硬段间的氢键作用增强,而硬段与软段间的氢键作用力减弱。微量水的存在可以对聚氨酯预聚体起到扩链作用,但随水量的增加预聚体会生成交联结构,产生不溶性凝胶。聚合温度的提高会加速聚脲结构的形成。     

原位聚合法制备纳米凹凸棒土/聚乳酸复合材料

将凹凸棒土（AT）进行提纯和有机改性后, 采用原位聚合法制备了OAT质量分数为1%、 3%、 5%的纳米凹凸棒土/聚乳酸复合材料（OAT/PLA-x）。采用红外、 扫描电镜、 X射线衍射等对复合材料进行了表征, SEM结果表明, 凹凸棒土粒子在复合材料中实现了均匀稳定分散。复合材料的力学性能和综合热性能测试表明: OAT/PLA-3复合材料的拉伸强度、 弹性模量分别比纯PLA增加98.6%和130.0%; 复合材料的热稳定性明显提高。同时, 复合材料的溶液降解速率也明显加快。