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本文研究工作表明,聚乙二醇作为聚对苯二甲酸乙二酯(PET)/聚对苯二甲酸丁二酯(PBT)共混体系的结晶促进剂,不仅使聚合物分子链运动容易而有利于结晶时定向排列,晶体生成速度加快,而且使成核的成效率提高,晶核生成速度加快,晶核数目增多而晶体尺寸减小,此外,PEG还部分参与了聚酯的酯交换反应,在低用量时有利于聚合物特性粘数提高,而且量增大则引起聚酯降解。由于PEG的这些作用,共混体系在PEG为6.0% 相似文献
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本文研究工作表明,聚乙二醇(PEG)作为聚对苯二甲酸乙二酯(PET)/聚对苯二甲酸丁二酯(PBT)共混体系的结晶促进剂.不仅使聚合物分子链运动容易而有利于结晶时定向排列,晶体生成速度加快.而且使成核剂的成核效率提高,晶核生成速度加快,晶核数目增多而晶体尺寸减小.此外,PEG还部分参与了聚酯的酯交换反应,在低用量时有利于聚合物特性粘数提高,而用量增大则引起聚酯降解.由于PEG的这些作用,共混体系在PEG为6.0%时的模量及γ-衰减强度最大.动态力学性能最好. 相似文献
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聚对苯二甲酸乙二酯的非等温结晶行为 总被引:2,自引:0,他引:2
用付里叶变换红外光谱法、示差扫描量热、广角X 射线衍射和密度法等手段,研究了聚对苯二甲酸乙二酯(PET)的非等温结晶行为.在110℃以上,PET的结晶度随温度的升高而增加;在160~230℃温度区间,PET的结晶度随温度的升高变化不大.但在其后的降温过程中,其结晶度显著增加.从高温缓冷试样的结晶度明显地比淬火试样的高.实验结果有力地支持了高聚物在结晶前链的折叠就已经形成的观点. 相似文献
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用直接酯化法合成了聚对苯二甲酸乙二酯(PET)。对缩聚反应温度、真空度及稳定剂等合条件对产物结晶速率的影响进行了研究。以ΔTc=Tc-Tg和ΔTco=Tco-Tg表征样品的结晶速率。结果表明,真空度一定,反应温度高则样品结晶速率慢;温度一定,真空度高样品结晶速率也慢。这两个因素的影响均是不可忽视的。 相似文献
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Jong Kwan Lee Hyo Jae Bang Kwang Hee Lee 《Journal of Polymer Science.Polymer Physics》2002,40(4):317-324
The lamellar‐level morphology of an extruded poly(ethylene terephthalate) (PET)/poly(ethylene‐2,6‐naphthalate) (PEN) blend was investigated with small‐angle X‐ray scattering (SAXS). Measurements were made as a function of the annealing time in the melt and the crystallization temperature. The characteristic morphological parameters at the lamellar level were determined by correlation function analysis of the SAXS data. At a low crystallization temperature of 120 °C, the increased amorphous layer thickness was identified in the blend, indicating that some PEN was incorporated into the interlamellar regions of PET during crystallization. The blend also showed a larger lamellar thickness than pure PET. A reason for the increase in the lamellar thickness might be that the formation of thinner lamellar stacks by secondary crystallization was significantly restricted because of the increased glass‐transition temperature. At high crystallization temperatures above 200 °C, the diffusion rates of noncrystallizable components were faster than the growth rates of crystals, with most of the noncrystallizable components escaping from the lamellar stacks. As a result, the blend showed an interfibrillar or interspherulitic morphology. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 317–324, 2002 相似文献
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PA6/PET共混体系的X射线衍射分析 总被引:2,自引:0,他引:2
用宽角X射线衍射分析,考察尼龙6/PET共混体系的结晶态,表明在共混物中尼龙6和PET是各自结晶的,即晶相分离的。研究了结晶条件,组份比等对晶态结构的影响,发现共混体系相对结晶度低于纯组份的算术加和,说明共混体系的结晶相分离过程中,由于存在相互作用导致的干扰,使结晶度下降。 相似文献
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Hyo Jae Bang Jong Kwan Lee Kwang Hee Lee 《Journal of Polymer Science.Polymer Physics》2000,38(20):2625-2633
Liquid–liquid phase separation and subsequent homogenization during annealing in an extruded poly(ethylene terephthalate) (PET)/poly(ethylene‐2,6‐naphthalate) (PEN) blend were investigated with time‐resolved light scattering and optical microscopy. In the initial stage, the domain structure was developed by demixing via spinodal decomposition. In the later stage, the blend was homogenized by transesterification between the two polyesters. The crystallization rate depended on the sequence distribution of polymer chains, which was determined by the level of transesterification rather than the composition change of separated phases. When the crystallization of PEN preceded that of PET, PEN showed a higher melting point. However, when the crystallization rate of PEN was slower than that of PET, the previously formed PET crystals suppressed the crystallization of PEN, causing the coarse crystalline structure of PEN to have a lower melting point. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2625–2633, 2000 相似文献
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本文用解偏振光法与DSC法分别测定并研究了PC/PET/EPDM共混体系的结晶速度、结晶度、Avrami指数(n)和熔融温度及其影响因素,共混物中PET的结晶速度、结晶度均随PC含量增加而下降;EPDM用量不超过10%时,可提高PET的结晶速度,但不影响结晶度和成核与增长方式,n值不变。当EPDM为5%时,结晶速度呈现极大值。经退火处理的共混物呈现熔融双峰,PC量增加,高温熔融峰略移向高温方向;热处理温度升高或时间延长,则低温熔融峰移向高温方向。 相似文献
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Zhong‐Ming Li Wei Yang Liang‐Bin Li Bang‐Hu Xie Rui Huang Ming‐Bo Yang 《Journal of Polymer Science.Polymer Physics》2004,42(3):374-385
This study describes the morphology and nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET)/isotactic polypropylene (iPP) in situ micro‐fiber‐reinforced blends (MRB) obtained via slit‐extrusion, hot‐stretching quenching. For comparison purposes, neat PP and PET/PP common blends are also included. Morphological observation indicated that the well‐defined microfibers are in situ generated by the slit‐extrusion, hot‐stretching quenching process. Neat iPP and PET/iPP common blends showed the normal spherulite morphology, whereas the PET/iPP microfibrillar blend had typical transcrystallites at 1 wt % PET concentration. The nonisothermal crystallization kinetics of three samples were investigated with differential scanning calorimetry (DSC). Applying the theories proposed by Jeziorny, Ozawa, and Liu to analyze the crystallization kinetics of neat PP and PET/PP common and microfibrillar blends, agreement was found between our experimental results and Liu's prediction. The increases of crystallization temperature and crystallization rate during the nonisothermal crystallization process indicated that PET in situ microfibers have significant nucleation ability for the crystallization of a PP matrix phase. The crystallization peaks in the DSC curves of the three materials examined widened and shifted to lower temperature when the cooling rate was increased. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 374–385, 2004 相似文献
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Chunguang Wang Zishou Zhang Kancheng Mai 《Journal of Thermal Analysis and Calorimetry》2011,106(3):895-903
β-nucleated PP/PET blends were prepared using nano-CaCO3 supported β-nucleating agent (β-NA), PP as matrix, and PET as dispersion phase. The effects of preparation methods, PET content, and melting temperature
on the non-isothermal crystallization behavior and the melting characteristic and polymorphic composition of PP in the blends
were investigated by differential scanning calorimeter (DSC) and wide angle X-ray diffraction (WAXD). The results indicated
that the PP crystallized predominantly in β-modification in the presence of β-NA. However, efficiency of β-NA for PP crystallization decreased with addition of PET and increasing PET contents. The β-nucleation of β-NA for PP crystallization in the blends was dependant on the preparation methods. The high β-nucleation and high β-PP content were obtained for PP/PET blend prepared at the temperature of 265 °C and added the β-NA into the blend at the temperature of 180 °C. However, the addition of β-PP or β-NA into blends at 265 °C decreased the β-nucleation, and no β-PP was formed because the β-NA mainly dispersed on the PET dispersion phase or at the interface between PP and PET. 相似文献
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E.El Shafee 《European Polymer Journal》2002,38(3):413-421
Binary blends of atactic poly(epichlorohydrin) (aPECH) and poly(3-hydroxybutyrate) (PHB) were investigated as a function of blend composition and crystallization conditions by dielectric relaxation spectroscopy. The quenched samples were found to be miscible in the whole composition range by detecting only one glass transition relaxation, for each composition, which could be closely described by the Gorden-Taylor equation. The cold-crystallized blends displayed two glass transition relaxations at all blend ratios indicating the coexisting of two amorphous populations: a pure aPECH phase dispersed mainly in the interfibrillar zones and a mixed amorphous phase held between crystal lamellae. The interlamellar trapping of aPECH was small and decreases with increasing the overall PHB content in the blend. At high crystallization temperatures the aPECH molecules was found to reside mainly in the interfibrillar regions due to its high mobility relative to the crystal growth rate of PHB. Our results suggest that because the intersegmental interaction in aPECH/PHB blends is weak, the mobility of the amorphous component at a given crystallization temperature decides diluent segregation. 相似文献
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Pitt Supaphol Nujalee Dangseeyun Pakin Thanomkiat Manit Nithitanakul 《Journal of Polymer Science.Polymer Physics》2004,42(4):676-686
Blends of poly(trimethylene terephthalate) (PTT) and poly(ethylene terephthalate) in the amorphous state were miscible in all of the blend compositions studied, as evidenced by a single, composition‐dependent glass‐transition temperature observed for each blend composition. The variation in the glass‐transition temperature with the blend composition was well predicted by the Gordon–Taylor equation, with the fitting parameter being 0.91. The cold‐crystallization (peak) temperature decreased with an increasing PTT content, whereas the melt‐crystallization (peak) temperature decreased with an increasing amount of the minor component. The subsequent melting behavior after both cold and melt crystallizations exhibited melting point depression behavior in which the observed melting temperatures decreased with an increasing amount of the minor component of the blends. During crystallization, the pure components crystallized simultaneously just to form their own crystals. The blend having 50 wt % of PTT showed the lowest apparent degree of crystallinity and the lowest tensile‐strength values. The steady shear viscosity values for the pure components and the blends decreased slightly with an increasing shear rate (within the shear rate range of 0.25–25 s?1); those of the blends were lower than those of the pure components. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 676–686, 2004 相似文献
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Morphology development and crystallization behavior of poly(ethylene terephthalate)/poly(trimethylene terephthalate) blends 总被引:1,自引:0,他引:1
Geon Seok Kim 《European Polymer Journal》2010,46(8):1696-3261
The spherulite morphology and crystallization behavior of poly(ethylene terephthalate) (PET)/poly(trimethylene terephthalate) (PTT) blends were investigated with optical microscopy (OM), small-angle light scattering (SALS), and small-angle X-ray scattering (SAXS). The thermal analysis showed that PET and PTT were miscible in the melt over the entire composition range. The rejected distance of non-crystallizable species, which was represented in terms of the parameter δ, played an important role in determining the morphological patterns of the blends at a specific crystallization temperature regime. The parameter δ could be controlled by variation of the composition, the crystallization temperature, and the level of transesterification. In the case of two-step crystallization, the crystallization of PTT commenced in the interspherulitic region between the grown PET crystals and proceeded until the interspherulitic space was filled with PTT crystals. The spherulitic surface of the PET crystals acted as nucleation sites where PTT preferentially crystallized, leading to the formation of non-spherulitic crystalline texture. The SALS results suggested that the growth pattern of the PET crystals was significantly changed by the presence of the PTT molecules. The lamellar morphology parameters were evaluated by a one-dimensional correlation function analysis. The blends that crystallized above the melting point of PTT showed a larger amorphous layer thickness than the pure PET, indicating that the non-crystallizable PTT component might be incorporated into the interlamellar region of the PET crystals. With an increased level of transesterification, the exclusion of non-crystallizable species from the lamellar stacks was favorable due to the lower crystal growth rates. As a result, the amorphous layer thickness of the PET crystals decreased as the annealing time in the melt state was increased. 相似文献