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首页> 外文会议>Thermoplastic Elastomers Topical Conference(TPE TopCon); 20070917-19; Akron,OH(US) >Morphology Development of (Sub)Micrometer Thermoplastic Vulcanisates
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Morphology Development of (Sub)Micrometer Thermoplastic Vulcanisates

机译：（亚）微米热塑性硫化橡胶的形态学发展

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Thermoplastic elastomers (TPEs) combine the elastic properties of thermoset cross-linked elastomers with the melt processability of thermoplastics (1,2). The strong growth of TPEs in the last decade is mainly related to the relatively low total-system-costs of end products produced via extrusion or injection moulding of TPEs, the possibility to recycle production scrap and after-use waste and, in some cases, an unique combination of physical properties. Thermoplastic vulcanisates (TPVs) are a particular class of TPEs, which are prepared via selective cross-linking of the rubber during mixing of a non-miscible blend of a semi-crystalline thermoplastic with a rubber (dynamic vulcanisation).Most commercial TPVs are based on blends of polypropylene (PP) andethylene/propylene/diene (EPDM) rubber, cross-linked with activated resol (1,2,3). In hindsight this can be explained by a combination of facts: ⅰ) PP has a high melting point, allowing relatively high-temperature applications, ⅱ) EPDM has a saturated main chain, resulting in a high resistance against ogygen, ozone, heat and light, ⅲ) PP and EPDM are compatible polymers, i.e. expensive compatibilisers are not required, and ⅳ) both polymers are relatively low cost. Resol cross-linking results in TPVs with a good balance of solid-state and melt properties. CommercialTPVs are produced on continuous extruders, which allow ⅰ) simple feeding of the various ingredients, ⅱ) have a high mixing efficiency, required for both dispersion of the two compatible polymers and of the resol cross-linker, and ⅲ) enable a high melt temperature, needed for the actual cross-linking.The final morphology of TPVs consists of a continuous thermoplastic phase with a cross-linked rubber dispersion (Fig. 1). This morphology explains the characteristic TPV properties. The elastic properties are related to the large quantity of cross-linked rubber particles, which are "connected" by the thermoplastic matrix (4,5). Melt processing is possible when the TPV is heated above the melting point of the semi-crystalline, thermoplastic, continuous phase; sufficient shear stress will enable flow (6). It has been shown that reduction of the dispersed rubber particles results in enhanced TPV tensile properties. Typical rubber domain sizes in commercial TPVs are in the 1 - 5 μm range. Smaller rubber particles can simply not be achieved on an extruder, because the shear forces are not large enough to overcome the large increase of interfacial tension upon further reduction of the particle size.
机译：热塑性弹性体（TPE）将热固性交联弹性体的弹性与热塑性塑料（1,2）的熔融加工性能结合在一起。在过去十年中，TPE的强劲增长主要与通过TPE的挤出或注射成型生产的最终产品的总系统成本相对较低，回收生产废料和使用后的废料以及在某些情况下可回收利用的可能性有关。物理特性的独特组合。热塑性硫化橡胶（TPV）是一类特殊的TPE，它是通过在半结晶热塑性塑料与橡胶的不可混溶混合过程中通过橡胶的选择性交联而制备的（动态硫化）。聚丙烯（PP）和乙烯/丙烯/二烯（EPDM）橡胶的混合物，并与活性甲阶酚醛树脂（1,2,3）交联。在事后看来，这可以通过以下事实加以解释：ⅰ）PP具有较高的熔点，可以在相对较高的温度下使用；ⅱ）EPDM的主链饱和，因此对氧气，臭氧，热和光的抵抗力很高，ⅲ）PP和EPDM是相容的聚合物，即不需要昂贵的相容剂，并且ⅳ）两种聚合物的成本都相对较低。甲阶酚醛树脂的交联导致TPV具有良好的固态和熔融性能平衡。商业TPV在连续挤出机上生产，这使得：ⅰ）简单添加各种成分；ⅱ）具有高混合效率；两种相容性聚合物的分散和可熔酚醛交联剂都需要； and）能够实现高熔融度TPV的最终形态是由连续的热塑性相和交联的橡胶分散体组成（图1）。这种形态解释了特征性的TPV特性。弹性特性与大量交联的橡胶颗粒有关，这些颗粒被热塑性基质（4，5）“连接”。当将TPV加热到半结晶，热塑性连续相的熔点以上时，可以进行熔融加工。足够的剪切应力将使流动（6）。已经表明，减少分散的橡胶颗粒导致增强的TPV拉伸性能。商业TPV中典型的橡胶畴尺寸在1-5微米范围内。较小的橡胶颗粒根本无法在挤出机上实现，因为剪切力不足以克服粒径进一步减小时界面张力的大幅增加。

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