一种耐热型聚氨酯弹性体的合成

在三聚催化剂的作用下,合成出了异佛尔酮二异氰酸酯的三聚体异氰脲酸酯,然后使它与聚酯多元醇反应,采用两步法手工浇注合成含异氰脲酸酯环的聚氨酯弹性体。采用红外光谱对该三聚产物进行了表征,并证实了异氰脲酸酯的存在。采用六氢吡啶法测出了异氰脲酸酯的质量分数。分别采用热重法和机械性能测试分析了弹性体的热稳定性和机械性能。结果显示,与普通聚氨酯弹性体相比,用异氰酸酯改性后的聚氨酯弹性体的热稳定性明显得到了提高。     

含异氰脲酸酯基团浇注型聚氨酯弹性体的合成及其耐热性能的研究

在催化剂作用下,合成了TDI-100型异氰脲酸酯,并与己二酸乙二醇丙二醇酯（PEPA）合成了浇注型聚氨酯弹性体,通过不同温度下的热失重分析（TGA）和弹性体的力学性能高温保持率对比分析表明,在TDI型聚氨酯弹性体中引入异氰脲酸酯基团,可明显提高弹性体的耐热性能。     

含异氰脲酸酯基团浇注型TDI聚氨酯弹性体的合成与其耐热性能的研究

在催化剂作用下,合成了TDI-100型异氰脲酸酯,并与己二酸乙二醇丙二醇酯二醇（PEPA）合成了浇注型聚氨酯弹性体,通过不同温度下的热失重分析（TGA）和弹性体的力学性能高温保持率对比分析表明,在TDI型聚氨酯弹性体中引入异氰脲酸酯基团,可明显提高弹性体的耐热性能。     

含异氰脲酸酯基团浇注型聚氨酯弹性体的动态性能研究

在催化剂作用下,合成了TDI-100型异氰脲酸酯,并与己二酸乙二醇丙二醇酯二醇（PE—PA）合成了浇注型聚氨酯弹性体,通过动态力学性能测试表明,在TDI型聚氨酯弹性体中引入异氰脲酸酯基团后,在动态条件下,弹性体的动态性能有一定程度的下降。     

聚异氰脲酸酯改性聚氨酯弹性体的RIM合成研究

通过异氰脲酯改性聚氨酯弹性体的化学组成及ＲＩＭ工艺条件的考察，确定了合知宾ＲＩＭ的化学组成和工艺条件，进而采用ＲＩＭ一步法合成了聚异氰脲酸酯改性聚氨酯弹性体，性能测试表明，在聚氨酯结构中引入改性的聚异氰脲酸酯环结构不仅能明显改善弹性体的热稳定性，而且还能显著提高弹性体的力学机械性能；并随异氰脲酸酯引入量的增加，弹性体的热稳定性和力学性能都相应提高。     

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。     

异氰脲酸酯基团对聚氨酯弹性体性能影响研究

引入异氰脲酸酯基团可提高聚氨酯弹性体的耐热性能,但同时对其他性能有一定影响。通过改变NCO含量考察异氰脲酸酯基团对聚氨酯弹性体的力学性能及耐溶剂性能的影响。力学性能测试结果表明,其硬度、拉伸强度和撕裂强度均在NCO质量分数为8％时达到极大值,分别为邵A60、10．33MPa和48．84kN／m,扯断伸长率随NCO含量增加单调减小,100％定伸强度单侧增大;耐溶剂实验表明,聚氨酯弹性体在NCO质最分数为8％时耐溶剂性能最好。     

耐热聚氨酯弹性涂料的制备

简介了用聚所酯弹性体与耐高温材料混合及对聚氨酯预聚体或原料先进行改性以及制备耐热聚氨酯弹性涂料的方法。对影响异氰脲酸酯－恶唑烷酮恶唑烷酮环和异氰脲酸酯环的因素进行了讨论。     

聚氨酯弹性体的力学性能和热性能研究

研究了以ＨＤＩ异氰脲酸酯（ＨＤＩ三聚体）和ＨＤＩ缩二脲（Ｎ１００）与聚醚制得的聚氨酯弹性体的力学性能和热性能。结果表明,含异氰脲酸酯基的弹性体的拉伸强度和断裂伸长率高于缩二脲弹性体,而两者的弹性模量相当。此外,含异氰脲酸酯基的弹性体还有较好的热稳定性。     

异氰脲酸酯改性MDI及聚氨酯弹性体合成研究

在催化剂作用下，ＭＤＩ自聚生成环状异氰脲酸酯，用此改性ＭＤＩ合成了聚氨酯弹性体。试验结果表明，ＭＤＩ在ＤＭＰ－３０催化作用下的自聚产物主要为三聚体异氰脲酸酯，ＤＭＰ－３０浓度为０．８％时，改性ＭＤＩ－的ＮＣＯ基含量约为ＭＤＩ中含量的５０％；温度对改性程度的影响不明显，在５０℃时改性程度最高；以改性ＭＤＩ合成的弹性体，其热稳定性和力学性能随改性程度的增加而提高。     

Morphology of polyurethane–isocyanurate elastomers

The dynamic viscoelastic properties and thermal transition behavior of reaction injection molding (RIM) and cast polyurethane—isocyanurate elastomers have been studied as a function of various segments (soft and hard urethane, and hard isocyanurate) content. RIM and cast elastomers were prepared at different concentrations of soft and hard urethane, and hard isocyanurate segments. RIM elastomers with the higher isocyanate index (lower hard urethane and greater isocyanurate segment content) displayed an unchanged T_g (glass transition temperature of soft segment) and increasing T_gh (glass transition temperature of hard segment) related to the hard urethane and isocyanurate segments. This is due to the phase separation between the soft and the hard segments. Cast elastomers synthesized from the higher amount of 1,4-butanediol (greater hard urethane and less hard isocyanurate segment content) showed an increasing T_gs, decreasing T_gh of hard urethane segments, and an unchanged T_gh of isocyanurate segments. This is related to the phase mixing between the soft and the hard urethane segments and the phase separation of hard isocyanurate and hard urethane segments.     

Polyurethane elastomers made from linear polybutadiene diols

Segmented polyurethane elastomers made from linear polybutadiene diols terminated with primary (Krasol LBH‐P) or secondary (Krasol LBH) hydroxy groups, alicyclic diisocyanate, and aliphatic chain extender were prepared and tested. The system was chemically crosslinked either through isocyanurate, that is, hexahydro‐1,3,5‐triazine‐2,4,6‐trione groups (formed by catalyzed cyclotrimerization of isocyanate groups), or by low molecular weight triols. The best balance of stress‐strain properties and reasonable thermal stability was obtained for systems in which only a small amount of chemical crosslinks was present in predominantly physically crosslinked networks. The influence of the type of polymer diol, chemical crosslinking, diisocyanate, and technique of preparation on mechanical, thermal, and swelling properties is discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 84–91, 2002     

The effect of the trimerization catalyst on the thermal stability and the fire performance of the polyisocyanurate‐polyurethane foam

In this work, 3 currently used trimerization catalysts, TMR‐2 (quaternary ammonium), K‐15 (potassium octoate), and PU‐1792 (potassium acetate) were used to produce rigid polyisocyanurate (PIR) foams with certain amounts of isocyanurate contents. The results from Fourier transform infrared (FTIR) quantitative analysis showed that PU‐1792 had the highest catalytic efficiency in isocyanurate formation. Then, the effect of different amounts of PU‐1792 catalyst on isocyanurate ring output was further investigated, and the result showed that the highest amount of isocyanurate ring formation could be attained by the 5 pphp of PU‐1792 catalyst. It was also found that the increased amount of isocyanurate ring could result in reduced cell size, improved compressive strength, and lowered thermal conductivity of PIR foam. The results from thermogravimetric analysis (TGA) and cone calorimeter (CONE) test revealed that the thermal stability and fire performance of PIR foam could be improved with the increased amount of isocyanurate ring. Furthermore, the CONE test indicated that the smoke production of PIR foam decreased approximately 51.7% in comparison to the reference polyurethane (PU) foam, and the SEM image of char morphology showed that the char of PIR foam was more compact than PU foam.     

New Polyurethane Elastomers with Enhanced Thermal Stability

A series of polyurethane elastomers with enhanced thermal stability was prepared and their physical and thermal properties were studied. For this purpose in the first step, an excess amount of methylene diphenyl diisocyanate was reacted with poly(tetramethylene ether) glycol to produce isocyanate-terminated polyurethane pre-polymer. In the second step, a new imide-based diol chain extender was synthesized via reaction of benzophenonetetracarboxylic dianhydride with 5-amino-1-naphthol. Finally, reaction of the pre-polymer with chain extender resulted in preparation of polyurethane elastomers. Presence of imide unit in the polymer backbone improved their properties and enhanced thermal stability of polyurethane.     

Effect of fillers on thermal and mechanical properties of polyurethane elastomer

The effects of five different types of fillers on the thermal and mechanical properties of hydroxyl-terminated polybutadiene-based polyurethane elastomers were explored to develop a filled polyurethane elastomeric liner for rocket motors with hydroxyl-terminated polybutadiene-based composite propellants. Two type of carbon black, silica, aluminum oxide, and zirconium(III) oxide were used as filler. Based on the improvement in the tensile properties and the erosion resistance achieved in the first part of the study, an ISAF-type carbon black was selected to be used as the main filler in combination with an additional filler. The second part involves the investigation of polyurethane elastomers containing a second filler in various amounts in addition to the ISAF-type carbon black used as the main filler. In addition to the thermal and mechanical properties, the processability of the uncured polyurethane mixtures were also explored by measuring the viscosity in this second part of the study. The studied fillers do not considerbly change the thermal degradation temperatures and the thermal conductivity of the polyurethane elastomers with a filler content up to 16 wt %. The best improvement in the erosion resistance and tensile strength of the polyurethane elastomers with additional fillers is also achieved when filled with the ISAF-type carbon black, whereas the use of zirconium(III) oxide as additional filler provides almost no improvement in these properties. Viscosity of the uncured polyurethane mixtures increases with the increasing filler content and with the decreasing particle size of the filler. Aluminum oxide-filled elastomers seem to be the most suitable compositions having sufficiently high thermal and mechanical properties, together with the processability of uncured mixtures. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1057–1065, 1998