热塑性聚氨酯与三元乙丙橡胶双连续相共混体系的结构与性能的研究

【作者】 苏玉峰；

【导师】 汪晓东；

【作者基本信息】 北京化工大学 ， 材料学， 2003， 硕士

【摘要】 本研究将聚酯型热塑性聚氨酯(thermoplastic polyurethane, TPU)与三元乙丙橡胶(ethylene propylene terpolymer, EPDM)共混,在双螺杆挤出机上制备了TPU/EPDM共混体系,并对共混物的亚微相态、热性能、动态力学性能及力学性能进行了考察。扫描电镜观察发现,TPU/EPDM共混体系在较大的比例范围内,形成了具有网化结构的聚合物共混物,其中,EPDM以连续的网化结构分布于TPU基体中,随EPDM含量的不同,所形成网化结构的尺寸及规整性也明显不同,当TPU/EPDM的比例为92/8时,网化结构最为完善。拉伸实验表明,随EPDM含量的不同,即随共混物网化结构的变化,共混体系的力学性能也产生显著改变,当TPU/EPDM=92/8时,拉伸强度和断裂伸长率等均获得最大值。 用傅立叶变换红外光谱法(FTIR)分析了共混前后TPU体系中氢键的分布情况。TPU硬段中含有可提供质子的亚甲基N-H和可提供电子的C=O基,软段中也含有可提供电子的酯基-COO-,因此在TPU的硬-硬段、硬-软段之间广泛分布着氢键作用。通过FTIR测试,可以清楚地观察到共混前后TPU体系中氢键分布的变化情况。结果表明,TPU的硬段与EPDM不相容。 分别用差示扫描量热法(DSC)、动态力学分析法(DMA)研究了TPU的软段与EPDM的相容性。结果表明,TPU软段的玻璃化转变温度Tg约为-46～-45℃,EPDM的Tg约为-50℃,其共混物只存在一个较宽的Tg温度转变区,且介于两纯组分的Tg之间。说明TPU的软段与EPDM之间具有一定的相容性。 用万能力学测试机对TPU/EPDM共混体系进行拉伸实验,结果表明,随EPDM含量的不同,TPU/EPDM共混体系的力学性能也产生与网化结构相应的变化,其拉伸强度、断裂伸长率等呈现出先升高后降低的变化趋势,当TPU/EPDM=92/8时,获得最大值,与亚微相态观察的结果完全吻合。 用毛细管流变仪研究了TPU及TPU/EPDM共混体系的流变特性。表明EPDM的加入在一定程度上加宽了TPU的加工温度范围,改善了TPU的“温敏性”和成型加工性。 <WP=4> 研究了增容剂对TPU/EPDM共混体系亚微相态和力学性能的影响。结果表明,POE-g-MA和SEBS-g-MA的加入,有效改善了TPU与EPDM之间的相容性,如TPU/EPDM/POE-g-MA=80/20/3的共混体系比TPU/EPDM=90/10的共混体系的网化结构更加完整化和规则化。此时的拉伸强度和断裂伸长率比增容剂用量为1%和5%的体系大。更多还原

【Abstract】 In this study, thermoplastic polyurethane (TPU) and ethylene propylene terpolymer (EPDM) blends were prepared by melt blending through a twin-screw extruder. Morphology, thermal properties, dynamic mechanical properties, mechanical properties, and rheological behavior were investigated. Scanning electronic microscope (SEM) observation showed that TPU/EPDM blends exhibited a co-continuous phase structure in a wide range of blending ratio, where EPDM formed a network in TPU matrix. The morphology of TPU/EPDM blends demonstrates a different network size with the change of EPDM content. A fine and complete network structure of EPDM in TPU matrix was achieved at the ratio of 92/8 (TPU/EPDM). The tensile strength and elongation at break of TPU/EPDM blends increased with the increasing of EPDM content. The mechanical properties reached maximal values at the ratio of 92/8 (TPU/EPDM). Continual increasing of EPDM resulted in a decreasing of the mechanical properties. Fourier transform infra-red spectroscopy (FTIR) determination of TPU/EPDM blends showed that the hard segments of TPU and EPDM was incompatible. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) investigations of TPU/EPDM blends showed that the soft segments of TPU and EPDM were compatible to some extent. Characterization of rheological behavior indicated that the process ability of TPU was increased after it was mixed with EPDM. The mixing of compatibilizer with TPU/EPDM blends increased the compatibilization of TPU and EPDM to some extent. For the blend at the ratio of 80/20 (TPU/EPDM), when 3 percent POE-g-MA was added, the morphology exhibited a most perfect network structure than the blend at the ratio of TPU/EPDM (90/10).更多还原