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首页> 外文期刊>Journal of Applied Polymer Science >Influences of copolymer polyol on structural and viscoelastic properties in molded flexible polyurethane foams
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Influences of copolymer polyol on structural and viscoelastic properties in molded flexible polyurethane foams

机译：共聚物多元醇对模塑软质聚氨酯泡沫塑料结构和粘弹性的影响

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In this study, the viscoelastic and morphological properties of molded foams were investigated to determine the influence of the presence or absence of reinforcing particulate copolymer polyols (CPP). The molded foams were based on toluene diisocyanate (TDI) and glycerol-initiated ethylene-oxide endcapped polypropylene oxide and, in most samples, some amount of copolymer polyol. Two series of foams were studied. In Series 1, as CPP is added to the formulation, the amount of TDI fed is kept constant. This results in a constant amount of hard-segment content as the filler in the system displaces, by weight, the polyether polyol in the foam, and it increases the hard segment to soft segment ratio (HS/SS). In Series 2, the amount of hard-segment material is proportionally decreased as CPP is added, resulting in a constant HS/SS ratio. Structural investigations of the foams displayed rather similar textures. The cellular structures of a CPP-containing foam was very similar to a foam lacking the copolymer polyols, Transmission electron microscopy revealed that the CPP particles were well dispersed and that they possessed significant rigidity even at high temperature and under high compression. Although all of the foams were microphase-separated, they varied slightly in that the copolymer polyol containing foams exhibited higher weight fractions of extractables in both Series 1 and Series 2. This suggests that not all of the CPP material is covalently bonded into the polyol matrix. It; was found that temperatures above ambient as well as humidity plasticized the viscoelastic behavior of all the molded foams evaluated. It was also found that the copolymer polyol particles, as added to the molded foams of Series 1, increased load-bearing capabilities but had a negative effect on the stress relaxation, creep, and compression set properties. In particular, the viscoelastic properties of the CPP-containing foam were distinctly more time-dependent than those of the foam lacking these particles. However, the Series 2 foams show that most of these effects are a result of the increased HS/SS ratio and not a result of the CPP particulate. It was shown that adding CPP while maintaining a constant; HS/SS ratio improves percent load loss and load bearing under high-humidity conditions, two important properties in flexible polyurethane foams, Finally, it was shown that at high temperatures (ca. 100 degrees C), an additional relaxation mechanism occurs which cannot be attributed to changes in the HS/SS ratio, but must be a result of the CPP components themselves. This additional mechanism results in higher rates of load relaxation and creep in foams containing CPP at high temperatures for foams of both series. (C) 2000 John Wiley & Sons, inc. [References: 12]
机译：在这项研究中，研究了模制泡沫的粘弹性和形态学特性，以确定是否存在增强颗粒状共聚物多元醇（CPP）的影响。模制泡沫基于甲苯二异氰酸酯（TDI）和甘油引发的环氧乙烷封端的聚环氧丙烷，并且在大多数样品中基于一定量的共聚物多元醇。研究了两个系列的泡沫。在系列1中，由于将CPP添加到配方中，因此TDI的添加量保持恒定。当体系中的填料按重量置换泡沫中的聚醚多元醇时，这会导致恒定量的硬段含量，并且会增加硬段与软段的比率（HS / SS）。在系列2中，随着添加CPP，硬段材料的数量成比例地减少，从而导致恒定的HS / SS比。泡沫的结构研究显示出相当相似的质地。含CPP的泡沫的孔结构与缺少共聚物多元醇的泡沫非常相似。透射电子显微镜显示CPP颗粒分散良好，即使在高温和高压下也具有显着的刚性。尽管所有泡沫都是微相分离的，但它们的变化很小，因为在系列1和系列2中，含共聚物多元醇的泡沫均显示出较高的可萃取物重量分数。这表明并非所有的CPP材料都共价键合到多元醇基质中。它;发现高于环境温度和湿度可塑化所有评估的模塑泡沫的粘弹性行为。还发现，添加到系列1的模塑泡沫中的共聚物多元醇颗粒增加了承载能力，但是对应力松弛，蠕变和压缩形变性质具有负面影响。特别地，与不含这些颗粒的泡沫相比，含CPP的泡沫的粘弹性特性明显更具时间依赖性。但是，系列2泡沫表明，这些影响中的大多数是HS / SS比增加的结果，而不是CPP颗粒的结果。结果表明，在保持恒定的同时添加CPP; HS / SS比改善了高湿条件下的百分比负荷损失和负荷承受能力，这是软质聚氨酯泡沫的两个重要特性。最后，结果表明，在高温（约100摄氏度）下，会出现另外的松弛机制，这是无法避免的归因于HS / SS比率的变化，但必须是CPP组件本身的结果。对于这两个系列的泡沫，这种附加的机理导致在高温下含有CPP的泡沫的载荷松弛和蠕变速率更高。 （C）2000 John Wiley＆Sons，inc。 [参考：12]

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