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首页> 外文期刊>Journal of Applied Polymer Science >EFFECT OF TOLUENE DIISOCYANATE INDEX ON MORPHOLOGY AND PHYSICAL PROPERTIES OF FLEXIBLE SLABSTOCK POLYURETHANE FOAMS
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EFFECT OF TOLUENE DIISOCYANATE INDEX ON MORPHOLOGY AND PHYSICAL PROPERTIES OF FLEXIBLE SLABSTOCK POLYURETHANE FOAMS

机译：甲苯二异氰酸酯指数对柔性板坯聚氨酯泡沫的形态和物理性能的影响

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The effect of toluene diisocyanate (TDI) index on the physical properties, structure, and morphology of flexible slabstock polyurethane foams was investigated. Foams based on a 2700 molecular weight triol, 6 pph water, and varying amounts of an 80/20 mixture of 2,4- and 2,6-TDIs were characterized using a number of physical property and morphological measurements. Extraction experiments using dimethyl formamide (DMF) showed that increasing the index increased the level of covalent crosslinking with perhaps a maximum being reached at an index ca. 100. Viscoelastic measurements also supported the claim of increased crosslinking with TDI index. The initial load in load relaxation experiments at 65% strain systematically increased with increasing TDI while the percent decay in a 3-h period decreased. Temperature and/or humidity ''plasticized'' the load relaxation behavior in all the foams studied, indicating that the hard segment domain physical ''crosslinks'' play a significant role in the properties of these materials. Interestingly, compression set measurements appeared to be independent of the index, likely due to some level of hard segment continuity, but the induced recovery of the compression set at elevated temperatures was indeed sensitive to the index. The amount of recovery systematically increased with increasing TDI index due to the more enhanced ''recoverable'' covalent network. Scanning electron microscopy (SEM) studies of the foams showed that the cellular structure was not significantly affected by the index. However, SEM also showed that the structure of the high index foam was not greatly altered by the extraction process while the lowest index foam's cellular structure was severely disfigured. The fine structure of the foams was found to be influenced by the TDI index. Small angle X-ray scattering, differential scanning calorimetry, and dynamic mechanical analysis all provided evidence that an increase in the TDI index promoted some phase mixing of the soft and hard segments. FTIR showed that the short-range ordering within the hard segment domains displayed a maximum at an index of 100. This was attributed to the concentration of hard segment domains being lower at a lower index and their ordering being disrupted at higher indexes due to more extensive covalent crosslinking prior to completion of phase separation. Wide angle X-ray scattering results also confirmed that for the highest index level, the short-range ordering of the TDI moieties was decreased. (C) 1997 John Wiley & Sons, Inc. [References: 11]
机译：研究了甲苯二异氰酸酯（TDI）指数对柔性块状聚氨酯泡沫的物理性质，结构和形态的影响。使用多种物理性质和形态学测量方法，对基于2700分子量三醇，6 pph水和2,4-和2,6-TDI的80/20混合物的变化量的泡沫进行了表征。使用二甲基甲酰胺（DMF）进行的萃取实验表明，增加指数会增加共价交联的水平，可能在指数ca达到最大值。 100.粘弹性测量也支持增加TDI指数交联的说法。在载荷松弛实验中，在65％应变下的初始载荷随着TDI的增加而系统地增加，而在3小时内的衰减百分比降低了。温度和/或湿度“塑化”了所有研究泡沫中的载荷松弛行为，表明硬链段域的物理“交联”在这些材料的性能中起着重要作用。有趣的是，压缩永久变形的测量值似乎与指标无关，这可能是由于一定程度的硬段连续性所致，但是在高温下诱导的压缩永久变形的恢复确实对指标敏感。随着“可恢复”共价网络的增强，随着TDI指数的增加，恢复量会系统地增加。泡沫的扫描电子显微镜（SEM）研究表明，泡孔结构不受该指数的显着影响。然而，SEM还表明，高折射率泡沫的结构并未因萃取过程而发生很大变化，而最低折射率泡沫的孔结构被严重破坏。发现泡沫的精细结构受TDI指数的影响。小角度X射线散射，差示扫描量热法和动态力学分析都提供了证据，表明TDI指数的增加促进了软链段和硬链段的某些相混合。 FTIR显示，硬段域内的短程排序在索引为100时显示最大值。这归因于硬段域的浓度在较低索引下较低，并且由于范围更广，它们在较高索引下的排列被打乱了。在完成相分离之前进行共价交联。广角X射线散射结果还证实，对于最高的指数水平，TDI部分的短程有序性降低了。 （C）1997 John Wiley＆Sons，Inc. [参考：11]

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