含液晶基元聚氨酯对普通聚氨酯性能的影响

合成了一类既含有刚性液晶基元又含有柔性链段的主链型含液晶基元聚氨酯(LCPU)，以端羟基四氢呋喃-环氧乙烷共聚醚为基体材料，多异氰酸酯N-100为固化剂，探讨这类含液晶基元聚氨酯对聚氨酯弹性体力学性能的影响。结果表明，5种含液晶基元聚氨酯随着柔性链段长度的变化和在聚氨酯弹性体中加入比例的变化。表现出对聚氨酯弹性体力学性能的影响有较大的差异。与未改性聚氨酯弹性体相比，改性后聚氨酯弹性体共混物垃伸强座量大提高71％倍．断裂伸长率最大提高8．7倍．     

合成工艺对丁羟聚氨酯弹性体性能的影响

以丁羟液体橡胶(HTPB)、N,N-双(2-羟丙基)苯胺(BHA)和甲苯二异氰酸酯(TDI)制得丁羟聚氨酯预聚体,然后用3,3'-二氯-4,4'-二氨基二苯甲烷(MOCA)固化制备了丁羟聚氨酯弹性体;研究了合成方法、不同二元醇、反应温度、反应时间、预聚体中-NCO质量分数及固化工艺对丁羟聚氯酯弹性体力学性能的影响.利用红外光谱分析了不同固化温度的丁羟聚氨酯弹性体,结果显示弹性体的微相分离程度从高温到低温梯度降低.     

环氧改性生物降解聚氨酯弹性体的合成和性能研究

由聚己内酯（PCL）和聚乙二醇（PEG）分别与1,6-亚甲基二异氰酸酯（HDI）合成端异氰酸酯基聚氨酯,再与缩水甘油反应制备环氧改性聚氨酯（EUP）;六亚甲基二胺（1,6-己二胺,HMDA）作固化剂,与环氧改性聚氨酯（EUP）反应合成生物降解聚氨酯弹性体。这种弹性体的生物降解率可控制,物理性能优良。常规方法进行表征。结果表明,PEG基弹性体的降解性能优于PCL基弹性体,而机械性能则低于PCL基弹性体;PCL和PEG混合制备的EUP降解性能和机械性能最佳。     

Viscoelastic properties and heat generation in urethane elastomers

Static and dynamic properties were studied in a series of polyurethane elastomers as a function of selected compositional variables such as curative system, curative level, catalyst level, and curing temperature. A number of physical properties including swelling ratio, density, glass transition temperature, stress–strain behavior, and thermal conductivity were also measured on these elastomers. The selected variables affect dynamic mechanical properties as well as heat buildup. A good correlation was noted between the loss modulus and the heat generation. The loss modulus and the heat generation decrease with decreasing curative level. The elastomers cured with a mixture of triol and diamine give lower loss modulus and heat buildup than those cured with diamine alone. These responses are believed due to the increase in covalent crosslinks. The observed low heat generation of the elastomer cured with 0.2 phr azelaic acid as a catalyst level was also attributed to the high crosslink density. The curing temperature, in the range investigated, appears to have very little effect on the properties. Thus, the choice of formulation variables, especially the use of diamine–triol blends, provides an effective means of minimizing heat generation in dynamic applications of polyurethane elastomers.     

Synthesis,characterization, and propellant binder studies of new polyurethanes

Hydroxy-terminated ether- and ester-based prepolymers more suitable for propellant binder applications were prepared from tetrahydrofuran, propyleneoxide, and various discarboxylic acids. Polyurethanes were prepared from these prepolymers with various diisocyanates such as hexamethylenediisocyanate, toluene diisocyanate, and diphenylmethanediisocyanate, and the mechanical properties such as hardness, tensile strength, and elongation of these polyurethane elastomers were compared. The thermal degradation study of these polyurethanes was studied in the atmosphere of oxygen. Composite propellants were formed using these prepolymers as binder resins, toluene diisocyanate as the curing agent, ammonium perchlorate as the oxidizer, and aluminum as the fuel. Propellants having two different solid loadings (85 and 82%) were made and compared with respect to their unloading slurry viscosity and mechanical properties. The tensile strength, elongation, and ballistic performance parameters (theoretical) of these new propellant systems were promising.     

Studies on curing reaction kinetics and properties of the CPE as a modifier of polyester–urethane elastomer

Chlorinated polyethylene (CPE)-modified polyester prepolymers with NCO end groups were synthesized. The chain-extension reactions of the prepolymers with 3,3′-dichloro-4,4′-diaminodiphenylmethane were studied by Fourier transform infrared spectrometry and found to change from second-order reaction at lower temperature to first-order reaction at higher temperature for these reaction systems. The properties of CPE-modified polyurethane (PU) elastomers was also studied by dynamic mechanical property analysis. The experimental results showed that the CPE content increase would lead to a decrease of the mechanical properties of PU elastomers and result in a prolongation of the cream time of curing reaction systems, but would make the manufacturing process easier than before. It is suggested that the CPE may be selected as a delayed-action activator of curing reaction. © 1996 John Wiley & Sons, Inc.     

Novel quinoline-based polyurethane elastomers. The effect of the hard segment structure in properties enhancement

Polyurethane elastomers incorporating a quinoline moiety along their polymeric backbones and aliphatic, aromatic or heterocyclic crosslinkers have been synthesized and characterized. For this, NCO-terminated urethane oligomers were prepared from poly(butylene adipate) diol and methylene diphenyl diisocyanate and were subsequently chain extended with 2,4-quinolinediol and different crosslinkers. This study reports the influence of the different crosslinker chemical structures and the hard segment molar ratio on the thermal and dynamic mechanical thermal properties, as well as on the mechanical properties of these elastomers. The fluorescence spectra of polyurethane elastomers were determined at an excitation wavelength of 290 nm. The different chemical structures of the crosslinkers determine the hard segment cohesion and reduce the mobility of the soft phase, having an important effect on thermal stability and on the mechanical properties of the polyurethane films. Thus the incorporation of aromatic crosslinkers results in polyurethanes with lower elongation and stress at break. The highest mechanical properties were obtained for polyurethanes crosslinked with aliphatic crosslinkers.     

印刷用低硬度聚氨酯弹性体的合成

采用一步法合成了邵A硬度为0～60的聚氨酯弹性体,此类弹性体耐溶剂性好,可用于彩涂等印刷领域。并考察了异氰酸酯种类、指数、聚酯结构、固化温度对产品硬度、力学性能、耐溶剂性能的影响。     

HTBN/PTMG双软段聚氨酯弹性体的制备及力学性能研究

以甲苯二异氰酸酯(TDI)、端羟基聚丁二烯-丙烯腈共聚物(HTBN)、聚四氢呋喃醚二醇(PTMG)为主要原料,3,5-二甲硫基甲苯二胺(DMTDA)为扩连剂,采用浇铸法制备了聚氨酯弹性体。研究了聚氨酯预聚体中NCO含量、HTBN/PTMG质量比、PTMG相对分子质量和改变扩链剂用量以及热处理时间对聚氨酯弹性体力学性能的影响。结果表明,低相对分子质量PTMG和高热处理温度有利于提高聚氨酯弹性体的力学性能,当聚氨酯预聚体中HTBN/PTMG的质量比为50∶50、NCO质量分数为5.98%、NCO/NH2摩尔比为1.20、115℃下热处理2 h时,聚氨酯弹性体的力学性能最佳。     

三种二胺扩链剂浇注聚氨酯弹性体性能比较

以聚己二酸乙二醇酯二醇（PEA）,甲苯二异氰酸酯（TDI）为原料合成聚酯型聚氨酯预聚体,分别用3,3'－二氯－4,4'－二氨基二苯基甲烷（MOCA）、二氨基二甲硫基甲苯（DADMT）和2,4－二氨基－5－巯基甲苯（TX－1）作扩链剂合成聚氨酯弹性体,比较了这3种扩链剂对浇注工艺性能及弹性体的物理机械性能的影响。实验结果表明,DADMT和TX－1两种固化剂得到的聚氨酯弹性体与固化剂（MOCA）得到的聚氨酯弹性体的力学性能相当,TX－1是一种能在常温下与预聚体进行固化反应的扩链剂,可以替代MOCA用于浇注型聚氨酯弹性体。     

CR/HPVC热塑性弹性体的性能研究

选用氯丁橡胶（CR）和高聚合度聚氯乙烯（HPVC）为主体材料，用动态硫化法制备了一类性能优异的材料－CR／HPVC共混型热塑性弹性体（TPE）。研究了共混方法、硫化温度、硫化体系、硫化剂用量及硫化时间等因素对动态硫化CR／HPVC热塑性弹性体力学性能的影响。     

NBR/HPVC热塑性弹性体的性能研究Ⅱ

选用丁腈橡胶(NBR)和高聚合度聚氯乙烯(HPVC)为主体材料,用动态硫化法制备了一类性能优异的材料—丁腈橡胶/高聚合度聚氯乙烯共混型热塑性弹性体(TPE),研究了共混方法,硫化温度,硫化体系,硫化剂用量,硫化时间等因素对动态硫化NBR/HPVC热塑性弹性体力学性能的影响。     

耐酸碱聚氨酯弹性体胶辊的研制

以端羟基聚丁二烯(HTPB)和聚四亚甲基醚二醇(PTMEG)为软段,2,4-甲苯二异氰酸酯(TDI-100)和3,3′-二氯-4,4′-二氨基二苯基甲烷(MOCA)为硬段,采用预聚体法制备了聚氨酯弹性体,讨论了不同软段比例对弹性体力学性能、耐酸碱性能及加工性能的影响。结果表明,软段中HTPB与PTMEG质量比为50∶50时,弹性体的综合性能较好,适合做耐酸碱胶辊的包覆胶。     

不同异氰酸酯型聚氨酯弹性体的制备与力学性能研究

采用不同结构的异氰酸酯和多元醇制备了一系列聚氨酯弹性体,主要考察了异氰酸酯种类对聚氨酯弹性体力学性能的影响.研究表明,由1,5-萘二异氰酸酯制得的弹性体拉伸强度和撕裂强度较高,分别为38.75MPa和109.77 kN/m,而由对苯二异氰酸酯制得的弹性体具有最大的扯断伸长率(557.84％).此外还研究了多元醇种类和扩链系数α对弹性体力学性能的影响,研究表明,选用聚ε-己内酯二醇制得的弹性体具有较好的性能,且拉伸强度和撕裂强度均随扩链系数的增大先增大后减小,而扯断伸长率一直增大.     

高硬度透明聚氨酯材料的研制

选用不同结构的多异氰酸酯、低聚物多元醇、扩链剂等为原料,用半预聚体法和一步法制得一系列高硬度高透明性聚氨酯材料。讨论了合成工艺、多异氰酸酯结构、扩链剂结构和多元醇平均每个羟基所对应的相对分子质量(N值)及其平均官能度对聚氨酯材料性能的影响。结果表明,选择异佛尔酮二异氰酸酯及扩链剂E并控制多元醇平均官能度在2.5～2.7和平均N值在120～150范围内,采用半预聚法制得的高硬度透明聚氨酯材料具有较好的综合力学性能及热稳定性。     

对苯二异氰酸酯型聚氨酯弹性体的合成及性能研究

以对苯二异氰酸酯(PPDI)、低聚物多元醇和小分子二元醇等为原料合成了PPDI浇注型聚氨酯弹性体,考察了不同低聚物多元醇对弹性体的物理机械性能、动态力学性能及热氧老化性能的影响,并与MDI和TDI型聚氨酯弹性体进行了比较。结果表明,PPDI型聚氨酯弹性体较MDI、TDI型弹性体具有更低的内生热、更高的回弹性,可用于轮胎胎面材料的制备。     

湿热环境用室温固化聚氨酯的研制

采用不同类型的多异氰酸酯、低聚物多元醇、扩链剂以及助剂等原料,制备了系列室温固化聚氨酯材料,讨论了原材料种类对聚氨酯弹性体力学性能和工艺性能的影响。结果表明,选用4,4′-二环己基甲烷二异氰酸酯(H12MDI)为异氰酸酯,聚氧化丙烯醚多元醇为聚合物多元醇,二乙基甲苯二胺(E-100)为扩链剂并配以特殊助剂制备的室温固化聚氨酯材料具有优异的力学性能和工艺性能,湿热条件对该材料最终性能和工艺性能的影响很小,特别适用于无法提供加热条件的湿热环境中。     

异氰脲酸酯改性聚氨酯弹性体的合成及研究

本文通过对异氰脲酸酯改性聚氨酯聚合反应过程的研究为基础，从各种异氰酸酯、聚醚二元醇、扩链剂及合适催化剂为反应组份，利用ＲＩＭ一步法和预聚物浇注二步法合成了系列异氰脲酸酯改性聚氨酯弹性体。通过对所制弹性体性能研究表明：在聚氨酯分子链中引入异氰脲酸酯环改性，可提高和改善弹性体的性能，随异氰脲酸酯含量的增加，弹性体的热稳定性和刚性显著增加。比较研究了两种不同方法合成的弹性体的结构形态和性能，结果表明一步法体系，由于其聚合速率快，体系中氨酯硬段和异氰脲酸酯硬段不同于二步法的较慢反应，它们没有足够时间发生相分离而互相混合，表现在ＤＳＣ曲线上只有一个Ｔｇｈ（硬段玻璃化温度），弹性体结构中含有氨酯、异氰脲酸酯相互混合的一个硬段区，结果表现在弹性体性能上，逊于结构中含有氨酯、异氰脲酸酯两个相分离的硬段区（有两个Ｔｇｈ）的二步法合成的弹性体材料。     

Interpenetrating polymer networks based on thermoplastic polyurethanes (TPUS) and cis-1,4-polyisoprene

Semi-interpenetrating polymer networks based on two elastomers, cis-1,4-polyisoprene (PI) and thermoplastic polyurethane elastomers (TPUs) were prepared in varying compositions. The PI component was cross-linked using peroxide initiators. Modulus and mechanical properties were investigated as a function of composition and temperature. Slight synergisms were observed in mechanical properties, particularly for compositions containing 10% PI by weight. Little or no molecular mixing is shown by differential scanning calorimetry (DSC) for these two-phase materials. © 1994 John Wiley & Sons, Inc.     

聚酯—聚硅氧烷嵌段聚氨酯弹性体的研究

用半凝胶法合成聚酯型和聚硅氧烷—聚酯型嵌段聚氨酯,结果表明：ＮＣＯ／ＯＨ当量比、ＭＯＣＡ用量对材料的物理性能有很大的影响。在聚合物主链引入硅氧烷后,弹性体力学性能略为降低,而疏水性得到提高。ＤＳＣ的分析表明,引入的聚硅氧烷链段主要分布于弹性体分子中的软段,使弹性体的相分离更加明显,低温区Ｔｇ发生外移。