In-situ microfibrillar PET/iPP blend via slit die extrusion, hot stretching, and quenching:: Influence of hot stretch ratio on morphology, crystallization, and crystal structure of iPP at a fixed PET concentratior
In-situ microfibrillar PET/iPP blend via slit die extrusion, hot stretching, and quenching:: Influence of hot stretch ratio on morphology, crystallization, and crystal structure of iPP at a fixed PET concentratior
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DOI：
10.1002/polb.20262
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发表时间：
2004-11-15
影响因子：
--
通讯作者：
Huang, R
中科院分区：
文献类型：
--
作者：
Li, ZM;Li, LB;Huang, R
采用狭缝模挤压、热拉伸和淬火工艺制备了聚对苯二甲酸乙酯(PET)/等规聚丙烯（iPP）原位微纤维共混物。形态学观察表明，虽然未拉伸共混物似乎是一种常见的不相容形态，但热拉伸共混物存在PET原位纤维，其特征，如直径和长径比，取决于热拉伸比（HSR）。当高铁比较低时，拉长的分散相颗粒不均匀。当HSR增加到16.1时，原位生成了定义明确的PET微纤维，其直径相当均匀，约为0.6，与0.9 mum相似。PET相的存在对iPP的结晶具有显著的成核能力。HSR越高，iPP基体的结晶速度越快，当HSR高到一定程度时，其变化对熔体冷却过程中iPP基体的开始结晶温度和最高结晶温度影响不大。光学显微镜观察发现，在微纤维共混物中形成跨晶层，其中PET微纤维为中心排核。在拉伸后的微纤维共混物中，小角度x射线散射测量表明，基体iPP片层晶体的取向与PET片层晶体相同。iPP片层晶体的长周期不受PET微纤维存在的影响。广角x射线散射表明，拉伸共混物中存在β相iPP，其浓度随高噪比的增加而增加。这表明更细的PET微纤维可以促进β相的发生。(C) 2004 Wiley期刊有限公司
The in situ microfibrillar blend of poly(ethylene terephthalate) (PET)/isotactic polypropylene (iPP) was fabricated through a slit die extrusion, hot stretch, and quenching process. The morphological observation indicates that while the unstretched blend appears to be a common incompatible morphology, the hot stretched blends present PET in situ fibers whose characteristics, such as diameter and aspect ratio, are dependent on the hot stretching ratio (HSR). When the HSR is low, the elongated dispersed phase particles are not uniform at all. As the HSR is increased to 16.1, well-defined PET microfibers were generated in situ, whose diameter is rather uniform and is around 0.6 similar to 0.9 mum. The presence of the PET phase shows significant nucleation ability for crystallization of iPP. Higher HSR corresponds to faster crystallization of the iPP matrix, while as HSR is high up to a certain level, its variation has little influence on the onset and maximum crystallization temperatures of the iPP matrix during cooling from melt. Optical microscopy observation reveals that transcrystalline layers form in the microfibrillar blend, in which the PET microfibers play as the center row nuclei. In the as-stretched microfibrillar blends, small-angle X-ray scattering measurements show that matrix iPP lamellar crystals halve the same orientation as PET lamella. The long period of lamellar crystals of iPP is not affected by the presence of PET micofibers. Wide-angle X-ray scattering reveals that the beta phase of iPP is obtained in the as-stretched blends, whose concentration increases with the increase of the HSR. This suggests that finer PET microfibers can promote the occurrence of the beta phase. (C) 2004 Wiley Periodicals, Inc.