共查询到17条相似文献,搜索用时 218 毫秒
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单轴取向聚对苯二甲酸乙二酯非等温结晶动力学研究 总被引:2,自引:0,他引:2
采用等速升温DSC方法对单轴取向聚对苯二甲酸乙二酯 (PET)的结晶过程进行了研究 ,发现单轴取向PET的冷结晶峰表现为多重结晶峰 .等温DSC方法的研究结果进一步证实结晶重峰的存在 .为此 ,本文提出了一种依据非等温DSC曲线解析高聚物结晶动力学参数的新方法 .对单轴取向PET的研究结果表明 ,与其他方法相比较 ,由新方法计算出的理论曲线与实验数据能更好地吻合 .单轴取向PET的总的结晶过程由三个子结晶过程组成 .根据不同拉伸比 ,各个子过程的Avrami指数和质量分数的变化 ,对结晶机理进行了解释 .与各向同性PET样品相比 ,单轴取向PET在低温部分的结晶速率明显增快 相似文献
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采用DSC方法研究了聚对苯二甲酸乙二酯 (PET)和热致性液晶共聚酯 6 0PHB PET (LCP)体系在少量扩链剂双 (2 唑啉 ) (BOZ)存在下形成的反应性共混物的非等温结晶动力学 .结果表明反应性共混物的Avrami指数均在 3 0~ 4 5之间 ,BOZ的加入使反应共混物中PET组分的结晶速率降低 ;表明BOZ对酯交换的促进作用 ,使所生成的共聚酯中PET嵌段的数均序列长度变短 ,而使结晶在某种程度上较为困难 ,但对体系的成核和结晶生长机理无明显影响 .结果还表明 ,随冷却速率的增大结晶峰向低温方向移动 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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PET/PC共混体系的酯交换反应对其高压结晶行为的影响 总被引:1,自引:1,他引:0
利用转矩流变仪、DSC、SEM及WAXD等表征手段研究了PET/PC共混体系的酯交换反应对其高压结晶行为的影响.SEM观察表明,PET和PC熔混时的酯交换反应有利于PET/PC体系在高压结晶时生成厚度较大的伸直链晶体,且可以促进其高压下酯交换反应的发生.楔形伸直链晶体和弯曲伸直链晶体的存在证明链滑移扩散和酯交换反应两种机制对体系中聚酯伸直链晶体的增厚有贡献.拟合分峰法和War-ren-Averbach傅里叶分析法的计算结果表明,随PET/PC体系熔混时酯交换反应程度的增加,高压结晶共混物的结晶度降低,PET的平均微晶尺寸增大,点阵畸变平均值则减小,而微晶尺寸分布变宽.提出了在共聚物组分都具备结晶能力时,结晶诱导化学反应和化学反应诱导结晶两种过程在一定条件下可同时发生的观点. 相似文献
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PTT/PET共混体系晶体形态与结晶性能的研究 总被引:1,自引:0,他引:1
用差示扫描量热仪(DSC)、广角X射线衍射(WAXD)和正交偏光显微镜研究了聚对苯二甲酸丙二酯(PTT)和聚对苯二甲酸乙二酯(PET)共混体系的晶体形态与结晶性能.结果表明,共混体系结晶性能与PTT的含量有关.PET的加入,使共混体系的球晶尺寸减小.球晶完善性降低.当PTT含量为40wt%~60wt%时,共混物分别出现了双重熔融峰和双重结晶峰.双重熔融峰是加热过程中熔融重结晶造成的,双重结晶峰说明不完善的晶体产生的次级结晶. 相似文献
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用DSC研究阻燃PET的结晶性和结晶动力学 总被引:2,自引:0,他引:2
<正> 聚对苯二甲酸乙二酯(PET)是一种熔点较高的结晶性聚合物,其结晶性和结晶动力学已得到了广泛的研究。我们最近合成的一种含磷聚合物(或齐聚物)聚苯基磷酸二苯砜酯(PSPPP),可作为PET纺丝较为理想的阻燃剂。当PET中添加5wt%的这种阻燃剂时,其极限氧指数可达到30。然而,有关这种阻燃剂的加入对PET结晶特性的影响方面的研究鲜见报道。本文用DSC方法研究了阻燃剂添加量的多少对PET结晶程度的影响,并且对纺制阻燃PET纤维的实用添加量5wt%的试样进行了结晶动力学研究。 相似文献
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采用冷冻萃取聚对苯二甲酸乙二酯(PET)溶液(0.1~10g/dL7种不同浓度,3种不同性能溶剂)的方法制备了解缠结PET试样.与链相互穿透且缠结的熔体骤冷试样相比,解缠结PET试样的结晶能力明显增强,且随着制样溶液浓度的降低,链间解缠结程度增加,PET的结晶能力逐渐增强,有序结构含量明显增加,但是如果制样溶液浓度太低,溶液中链间距离太大,则又不利于萃取过程中链间的有序堆砌而结晶.采用接触浓度c*附近的溶液,既可确保链间的有效解缠结又有利于链间的有序堆砌而结晶.PET的结晶能力甚至还受制样所用溶剂性能的影响,这是因为溶剂性能影响了溶液中链间的相互作用以及链的解缠结程度. 相似文献
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Thermal analysis techniques were performed to reveal ‘crystalline solvate’ behavior between organic compounds and polar solvents.
Diimide-dicarboxylic acid (DIDA) was formed by reacting 3,3'-diaminodiphenylsulfone (3,3'-DPS) or 4,4'-diaminodiphenylsulfone
(4,4'-DPS) with trimellitic anhydride (TMA) in some polar solvents (PSv). The products could crystallize upon cooling in a
polar solvent media to form a solvate containing a finite quantity of solvents, leading to what can be termed as ‘crystalline
solvates’ (CS). This study has demonstrated that sampling techniques in TG and DSC must be kept to be as similar as possible,
which is a critical point in practices of thermal analysis techniques. DSC analysis revealed that there are two endothermic
peaks in the CS, with the lower one being the de-solvate temperature of CS (T
d) at which the solvated solvent molecules were removed, and the higher peak being the melting point of the de-solvated DIDA
(T
m). T
d was found to vary with the types of polar solvents and structures of DIDA. The TG result indicated that most of the sulfone-based
DIDA-CS contained 2 moles of solvent per mole of solvate. X-ray analysis revealed that different crystalline structures were
found for DIDA-CS solvated with different solvent molecules, but all de-solvated DIDA possessed the same crystal unit.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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THE DOUBLE MELTING PEAKS OF POLY(ETHYLENE TEREPHTHALATE) 总被引:2,自引:0,他引:2
Three sets of PET samples, comprising original (undrawn), uniaxially drawn and biaxially ones, after annealed at 230°, 240°and 250℃respectively, were subjected to DSC thermal analysis, X-ray diffraction analysis and IR analysis. The results indicate that the phenomenon of double melting peaks during DSC analysis is due to the partial melting and recrystallization of the crystallite at the moment of thermal scanning. The lower temperature peak, which varies slightly according to annealing condition, corresponds to the melting of imperfect crystallite, and the higher temperature peak corresponds to the melting of better organized crystallite. In the course of temperature scanning, the unit cell parameters of PET remains unchanged while the crystals turn to better crystal lattice, greater crystal size and more regular folding.We also found that there is a slight reduction in crystal size between the two melting peaks, and an explanation is suggested for this phenomenon. 相似文献
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This work describes the investigation of complex peaks observed during the cold crystallisation of polyethylene terephthalate (PET) blended with polystyrene (PS). Blends of PET with 1% to 15% PS content were compounded in a laboratory internal mixer and quenched from the melt to produce substantially amorphous samples. The cold crystallisation behaviour was studied using differential scanning calorimetry (DSC) conducted at 10 °C/min. The complex peaks of the PET/PS blends were resolved as the sum of two simple peaks, and the component peak characteristics were determined. While the total crystallinity was found to be independent of the PS content, the areas under the component peaks depend on the amorphous component content. A simple model based on partial dissolution and micro-segregation of PS is proposed to qualitatively explain the presence of the double cold crystallisation peaks. 相似文献
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