Mechanical properties of hand-cast and reaction injection molded polyurethane and vinyl ester resin interpenetrating polymer networks

A series of simultaneous interpenetrating polymer networks (SINs) composed of polyurethane (PU) and vinyl ester resin (VER) was prepared from different rigid phase components, where the pendent hydroxyl groups of VER were retained or capped, and through different molding processes, i.e., hand-casting or reaction injection molding (RIM). It was recognized that the occurrence of chemical binding between PU and VER networks through the reaction of the diisocyanate and the pendent hydroxyl groups of VER played an important role in determining the mechanical properties of these SINs. The hand-cast SINs, with VER containing pendent hydroxyl groups as the rigid phase component and with these pendent hydroxyl groups counted for the metering of diisocyanate besides that due to polyether polyol and chain extender of PU phase, behaved like the hybrid polyester matrix. For the RIM-molded SIN samples, an obvious reinforcing effect of VER network, whose pendent hydroxyl groups were capped with acetyl groups, upon PU network was observed. These results correlated well with the knowledge of polymerization kinetics and morphology development of these PU/VER SINs.     

Synthesis,thermal properties,and morphology of blocked polyurethane/epoxy full‐interpenetrating polymer network

Blocked polyurethane (PU)/epoxy full‐interpenetrating polymer network (full‐IPN) were synthesized from blocked NCO‐terminated PU prepolymer, with 4,4‐methylene diamine as a chain extender and epoxy prepolymer, with 4,4‐methylene diamine as a curing agent, using simultaneous polymerization (SIN) method. From FTIR spectra analysis it was found that the major reactions in the blocked PU/epoxy IPN system are the self‐polymerization of block PU/chain extender and the self‐polymerization of epoxy/curing agent. Meanwhile, from reaction mechanisms the copolymerization of IPN may have occurred at the same time. The weight loss by thermogravimetric analysis decreased with increasing epoxy and filler content. It was confirmed from scanning electron micrography (SEM) that when the blocked PU content increased, the microstructure of IPN became rougher. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 323–328, 2006     

Physical properties of transfer-molded polyurethane-polyester interpenetrating polymeric network

A series of polyurethane-polyester simultaneous interpenetrating network (SIN) samples were prepared by a laboratory-scale transfer mold. The effect of compound composition and molding conditions on the tensile properties and crystallinity of molded parts was examined by using an Instron tensile tester and a Perkin-Elmer differential scanning calorimeter (DSC). It was found that incomplete polymerization resulted in a poor tensile strength of 80°C-molded SIN. Postcure treatment and higher molding temperature increased the tensile strength of SIN by improving their limiting conversion and possibly the morphology. Results indicated that postcure was more efficient than molding at higher temperature for SIN samples with high polyurethane content. On the other hand, for SIN with higher polyester content, a high molding temperature resulted in better mechanical properties than postcuring the low-temperature molded samples. Both reaction sequence and cross-linking nature of the constituent polymers had a profound effect on the tensile properties of SIN.     

Synthesis and thermal properties of polyurethane–polysiloxane crosslinked polymer networks

Polysiloxane–polyurethane crosslinked polymer networks (PSI–PU) were synthesized in solution by polymerization of oligosiloxanes containing γ‐hydroxy propyl groups with polymethane polyphenyl polyisocyanate. Polyether‐based polyurethane and polyester‐based polyurethane were also prepared by a “one‐shot” method. Their thermal properties were studied by thermogravimetric analysis. It was observed that the thermal stability of PSI–PU was better than that of polyether‐based polyurethane and polyester‐based polyurethane, and an inert atmosphere had no effect on decomposition of polyurethanes below 350°C. It was found that polyurethane–polysiloxane crosslinked polymer networks decomposed slower in oxygen than in nitrogen in the temperature range of 350–550°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 310–315, 2003     

Simultaneous interpenetrating networks of a polyurethane and poly(methyl methacrylate). II. Partitioning of MMA monomer in the last stages of polymerization

In a model polyurethane/poly(methyl methacrylate) (PU/PMMA) system, the partitioning of unreacted methyl methacrylate monomer (MMA) is studied in the late stages of its polymerization, simulated by incorporating controlled amounts of MMA in otherwise fully cured simultaneous interpenetrating networks (SIN) samples. Glass transitions temperatures (T_g) were determined using dynamic mechanical spectroscopy and differential scanning calorimetry as a function of MMA content of the SINs. The lowering of T_g in each phase due to the plasticization effect of MMA is used to calculate a plasticization coefficient for each phase, finally allowing calculation of the partition coefficient of MMA between the two phases. It is found that the MMA monomer distributes itself almost uniformly across the two phases of the current SIN system, leading to speculation as to the locus of late SIN polymerization. © 1995 John Wiley & Sons, Inc.     

Effect of reactive polyurethane on toughness of unsaturated polyester resin

Unsaturated polyester (UP) resin is one of the major thermosetting resins and is very useful as a matrix resin of composite material for its processibility. UP resin, however, has several shortcomings: it is weak in alkalis, volume shrinkage occurs during the crosslinking reaction of the oligomeric UP resin with a styrene monomer, and it is also brittle. The mechanical properties of UP resin can be enhanced by blending it with various materials. In this study, polyurethane (PU) was used as a modifier to improve the toughness of the UP resin. The effect of the polyol molecular weight as a PU soft segment and the PU contents on the toughness of PU‐modified UP resins were studied. A UP/PU polymer network may occur through a reaction between an isocyanate group in the methyl diisocyanate (MDI) and a hydroxyl one in the UP molecules. The maximum toughness was observed at approximately 2 wt % of the PU content. These results can be rationalized by the incorporation of a rubbery PU segment into a brittle UP resin. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 735–740, 2002; DOI 10.1002/app.10169     

Polymerization kinetics of polyurethane and vinyl ester resin interpenetrating polymer networks by using fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy (FTIR) was applied to the study of polymerization kinetics of simultaneous interpenetrating polymer networks (SINs) composed of polyurethane (PU) and vinyl ester resin (VER), in which the pendent hydroxyl groups were capped with acetyl groups to minimize the possibility of chemical binding between the two networks. It was found that during the course of synthesis the two pairs of reactants interfere with each other in the SIN systems, giving rise to depressed reaction rates, although they follow different polymerization mechanisms. Increasing the reaction temperature could be more effective than increasing the free-radical initiator level with regard to the final conversions of both components. The reaction sequence could be varied through the amount of the step-growth polymerization catalyst and free-radical initiator as well as the reaction temperature adjustment. Using VER containing pendent hydroxyl groups could strongly affect the reaction kinetics of such SINs and lead to hybrid structures. The quick formation of one network would always depress the conversion of the other network in all SINs studied. © 1996 John Wiley & Sons, Inc.     

Morphology,mechanical properties,and thermal stability of polyurethane–epoxide resin interpenetrating polymer network rigid foams

A series of rigid interpenetrating network foams (IPNFs) based on a rosin‐based polyurethane (PU) and a crosslinked epoxide resin (ER) were prepared by a simultaneous polymerization technique. The morphology, mechanical properties, thermal stability, and changes in the chemical structure during the thermal degradation process of the rigid IPNFs were investigated by scanning electron microscopy (SEM), compressive testing, thermogravimetric analysis (TGA), and Fourier‐transform infrared spectroscopy (FTIR). The SEM micrographs showed that the cell structure of the rigid IPNFs became less homogeneous with increasing ER content. The brittleness of the cell walls increased as the ER content and the cure time of the rigid IPNFs increased. The compressive strength of the rigid PU/ER IPNFs increased to a maximum value and then decreased with further increase in the ER content. Similar behavior was observed for the elastic modulus. This behavior was related to the nonhomogeneous cells and more brittle cell walls for the rigid IPNFs with high ER content. The TGA data showed that the thermal stability of the rigid PU foam increased with the addition of increasing levels of ER, due to the better thermal stability of the ER compared to that of the PU. With the exception of the ER alone, a two‐stage weight‐loss process was observed for all these rigid IPNFs and for the PU foam alone. The FTIR analysis suggested that the first stage of weight loss was due to the degradation of the polyol–derived blocks of the PU, and the second weight loss stage was governed by both the degradation of the ER component and that of the isocyanate‐derived blocks of the PU. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 406–416, 2000     

涂覆聚氨酯的聚酯/氨纶复合织物的定量分析研究

研究了涂覆聚氨酯(PU)的聚酯/氨纶复合织物(简称PU涂层复合织物)的定量分析方法,探讨了以四氢呋喃和环己酮作为溶剂在不同温度条件下对去除PU涂层复合织物中的PU涂层的效果,对去除PU涂层后的PU涂层复合织物进行其中的聚酯纤维含量(G)的测定并分析了未涂覆PU的相应聚酯/氨纶复合织物中的聚酯纤维含量(G0).结果表明:...     

用FTIR研究聚氨酯／不饱和聚酯IPN体系的反应动力学

利用傅里叶变换红外光谱研究聚氨酯不饱和聚酯互穿聚合物网络体系的反应动力学，求出了ＰＵ的反应速度常数ｋ。实验结果表明，ＰＵ在半－ＩＰＮ体系中的反应为二级反应，ＩＰＮ体系中ＰＵ组分与ＵＰ组分的反应相互影响：ＵＰ组分使ＰＵ组分的前期反应速度变慢，后期反应速度相对增加；ＰＵ组分使ＵＰ组分聚合的诱导期明显缩短。ＰＵ和ＵＰ的配比对反应转化率的影响是反应前期ＰＵ组分含量越高，ＰＵ组分反应转化率也越高；反应后期，     

聚氨酯改性环氧树脂胶粘剂的制备及性能研究

由端-NCO基聚氨酯(PU)预聚物与环氧树脂反应,制备了PU接枝改性环氧树脂。着重探讨了PU预聚物的含量、活性稀释剂的含量和异氰酸酯结构等因素,对改性环氧树脂的粘度和粘接性能的影响。实验结果表明,该改性环氧树脂的粘度随着PU预聚物含量的增加而逐渐增大,随着活性稀释剂含量的增加而逐渐降低,而且在相同的条件下,用不同的二异氰酸酯改性环氧树脂的粘度大小次序为:IPDI型>MDI型>TDI型;该改性环氧树脂在PU预聚物含量为20%时,对铝片/铝片的剪切强度最大(7.82 MPa);在PU预聚物含量为10%时,对铁片/铁片的剪切强度最大(11.70 MPa),而且TDI型和IPDI型改性环氧树脂的粘接性能明显好于MDI型改性环氧树脂。     

刚性聚氨酯增韧改性环氧树脂的研究

在环氧树脂(EP)中加入以对苯二甲酸二甲酯为原料合成的端羟基芳香聚酯及2,4—甲苯二异氰酸酯(TDI),采用原位聚合法制备了刚性聚氨酯(PUR)增韧改性EP。用红外光谱表征了其反应,探讨了端羟基芳香聚酯含量、端羟基芳香聚酯与TDI摩尔比和固化剂用量对改性EP力学性能的影响,并用扫描电子显微镜观察了改性EP的冲击断面。结果表明,在提高EP韧性的同时,改性EP的其它力学性能都得以提高。     

耐水解聚醚-聚酯型聚氨酯涂饰剂的研制

以聚四氢呋喃醚二醇（PTMG）、聚酯多元醇和二苯基甲烷二异氰酸酯等为主要原料，合成了一种聚醚-聚酯共聚型氨酯树脂，以该聚氨酯树脂、颜料及混合有机溶剂等原料，配制了耐水解聚氨涂饰剂，该聚氨酯涂饰用于聚氨酯合成革的表面涂饰。重点讨论了聚氨酯树脂聚醚含量对树脂物性、耐水解性能的影响，以及树脂的100%模量、粘度及涂饰剂溶剂体系对涂饰加工性能及合成革耐水解性能的影响，制得的聚氨酯涂饰具有良好的耐水解性能。     

Enhanced Mechanical and Dielectric Properties of PU Networks with Hyperbranched Structures

We report a new polyurethane (PU) dielectric containing hyperbranched structures and metal nanoparticles. Silver nanoparticles were incorporated into the PU networks by using hyperbranched polyester (HBP) as a reductive template as well as the cross-linker. Simultaneously enhanced mechanical and dielectric properties were observed in the hyperbranched PU dielectrics. The branched macromolecular fractal provides a “covalent bridge” between the PU matrix and Ag nanoparticles, which contributed to the simultaneously enhanced mechanical and dielectric properties.     

高耐候、耐磨型聚氨酯风电叶片涂料的研究

采用丙烯酸树脂和聚酯多元醇树脂拼用的方法制备了高耐候、耐磨型聚氨酯风电叶片涂料。通过改变丙烯酸树脂与聚酯多元醇树脂质量比设计了5个不同配方,分别对其涂膜性能进行表征并与某进口样品对比。试验表明,随着丙烯酸树脂用量的增加,涂膜的耐候性能随之变好;而增加聚酯多元醇用量时,则产品的耐冲击性能、附着力及耐磨性变优。所研制产品的耐磨性和附着力要优于某进口产品,且耐候性能与某进口产品相当。     

海洋操作平台钢结构用防护涂料的制备与性能

以聚己内酯、新戊二醇与顺丁烯二酸酐合成了聚酯树脂,然后与六亚甲基二异氰酸酯(HDI)反应以提高支化度,引入有机硅后再同丙烯酸单体反应制得丙烯酸改性聚酯树脂。以此丙烯酸改性聚酯树脂和适量的颜填料为甲组分、拜耳3390固化剂为乙组分,开发了适用于海洋气候的钢结构表面防护涂层。研究了顺丁烯二酸酐含量、丙烯酸改性聚酯树脂羟基含量、n(─NCO)∶n(─OH)值和聚合条件对面漆性能的影响。当顺丁烯二酸酐的用量为聚酯树脂的5%,自制的丙烯酸改性聚酯树脂羟基含量为4.5%±0.3%,n(─NCO)∶n(─OH)=1.1~1.4时,所制备的丙烯酸改性聚酯树脂面漆配以环氧富锌底漆及环氧云母氧化铁中涂漆得到的涂层体系能够满足海上平台钢结构的防护要求。     

Polyether and polyester polyol based glycidyl-terminated polyurethane modified epoxy resins: Mechanical properties and morphology

A glycidyl-terminated polyurethane prepolymer was synthesized and used to enhance the properties of epoxy resins. Some properties of glycidyl-terminated PU/epoxy with polyether based (PPG) and polyester based (PBA) glycidyl-terminated PU were investigated in this research. The polyether based glycidyl-terminated PU(PPG) modified epoxy resin proved to be superior to conventional epoxy resins in improved impact strength and fracture energy, but not tensile strength, tensile modulus, flexural strength and flexural modulus. On the other hand, the polyester based glycidyl-terminated PU(PBA) modified epoxy resin had increased mechanical properties while showing slight variation of impact strength and fracture energy. Different mechanisms for this behaviour are advanced in this paper.     

合成革用水性聚氨酯的制备

以异佛尔酮二异氰酸酯( IPDI),聚酯或聚醚多元醇、二羟甲基丙酸(DMPA)为主要原料,采用预聚体法合成了脂肪族革用水性聚氨酯(WPU),用三甲氧基三聚氰胺树脂(TMMM)对WPU进行交联反应成膜,考察了nNCO/nOH,DMPA用量、聚酯或聚醚种类以及TMMM对WPU性能的影响.结果表明,随着nNCO/nOH的增加...     

脲-异丁醛-甲醛缩聚树脂在涂料中的应用研究

将脲-异丁醛-甲醛缩聚树脂（UIFR）添加到醇酸树脂清漆、不饱和聚酯清漆、硝基清漆及聚氨酯清漆中,研究了UIFR用量对漆膜附着力、柔韧性、硬度、冲击强度、光泽度等物理机械性能的影响,并就其耐黄变性能与环己酮-甲醛树脂（CFR）进行了比较。结果表明：UIFR的加入可以有效提高漆膜的物理机械性能,且耐黄变性能明显优于CFR。UIFR的适宜用量为漆液固体份总质量的6％～12％。     

高固体分湿固化聚氨酯弹性体制备方法的探讨

采用MDI、PAPI、HDI、IPDI等不同的异氰酸酯和聚酯多元醇、聚醚多元醇等反应，制备高固体分的聚氨酯弹性体预聚物。实验探讨了预聚物的原材料、反应温度、NCO／OH比、反应时间以及实验工艺等对合成高固体分聚氨酯树脂(PU)的影响，还探讨了降低高固体分PU预聚物游离NCO的技术途径。