聚丙烯/聚(丙烯-g-马来酸酐)/蒙脱土纳米复合材料结晶动力学研究

非等温结晶动力学;聚丙烯/聚(丙烯-g-马来酸酐)/蒙脱土纳米复合材料结晶动力学研究     

聚丙烯/蒙脱土纳米复合材料非等温结晶动力学的研究

用熔融插层法制备聚丙烯 蒙脱土纳米复合材料 ,用DSC手段研究了其非等温结晶行为 ,并与聚丙烯进行了对比 .对所得数据分别用修正Avrami方程的Jeziorny法、Ozawa法和Mo法进行处理 .结果表明 ,用Jeziorny法和Mo法处理非等温结晶过程比较理想 ,而用Ozawa法处理则不太适用 .用Jeziorny法求出的参数Zc和n随冷却速率的增加而增加 ,但复合材料的Zc 和n略大于聚丙烯的Zc 和n ,用Mo法求出的参数F(T)随结晶度的增加而略有增加 ,a几乎未变 ,复合材料的F(T)略小于聚丙烯的F(T) ,复合材料的a约为 1.40略大于聚丙烯的a(其值约为 1.0 4) .按Kissinger方法计算出聚丙烯及聚丙烯 蒙脱土纳米复合材料的结晶活化能分别为 189.37kJ mol,15 5 .6 9kJ mol,说明有机蒙脱土的加入 ,降低了聚丙烯的结晶活化能 ,起到了异相成核的作用     

β-羟基丁酸与β-羟基戊酸共聚物 (PHBV)/蒙脱土纳米复合材料的等温结晶动力学

用差热量热分析（DSC）方法研究了β－羟基丁酸与β－羟基戊酸共聚物（PHBV）／蒙脱土纳米复合材料的等温结晶行为。结果表明，PHBV的Avrami方程指数n、成核机理、结晶生长方式基本不受蒙脱土的影响，加入少量的蒙脱土可明显降低PHBV结晶成核自由能，使其结晶速率增大。     

尼龙66/蒙脱土复合材料结晶行为的研究

在密炼机中采用熔融共混法制备蒙脱土重量分数为 2 5 %、4 5 %的尼龙 6 6 /蒙脱土复合材料 .通过DSC法对非等温结晶行为及在 2 2 8～ 2 4 0℃范围内的等温结晶行为进行研究 ,并与纯尼龙 6 6进行比较 .从其等温和非等温结晶行为的研究表明 ,蒙脱土起成核剂的作用 ,它的填入使尼龙 6 6结晶速率提高 ,但填料与基体间的相互作用使其链段运动困难 ,结晶活化能提高 ;在研究的填料含量变化范围内 ,结晶行为变化不大 ,并且找到该复合材料在 2 2 8～ 2 34℃范围结晶对温度的不敏感区 ;对非等温结晶过程分析 ,刘结平 莫志深方程是适用的 ,而Ozawa方程则是不适用的 .     

尼龙6/蒙脱土纳米复合材料的等温结晶动力学研究

用ＤＳＣ法研究了熔体插层制备的尼龙６／蒙脱土纳米复合材料的等温结晶行为．结果表明,加入少量的蒙脱土可明显提高尼龙６的结晶速率,降低球晶径向生长的单位面积表面自由能．从Ａｖｒａｍｉ方程和Ｈｏｆｍａｎ理论出发,得出蒙脱土纳米粒子的存在可明显改变尼龙６的结晶行为     

聚甲醛/蒙脱土纳米复合材料非等温结晶动力学研究

聚甲醛/蒙脱土纳米复合材料非等温结晶动力学研究     

聚甲醛/蒙脱土纳米复合材料非等温结晶动力学研究

聚甲醛/蒙脱土纳米复合材料非等温结晶动力学研究     

尼龙6/蒙脱土纳米复合材料非等温结晶动力学和透明性研究

将有机化的蒙脱土与尼龙6(PA6)在Haake共混机中共混,制备出尼龙6/蒙脱土纳米复合材料(PA6N);对尼龙6/蒙脱土纳米复合材料和纯尼龙6分别进行差示扫描量热法非等温结晶试验,以了解蒙脱土在尼龙6/蒙脱土纳米复合材料中的成核作用、扩大尼龙6在包装领域的应用范围.与此同时,采用偏光显微镜测定了样品的结晶形态;采用紫...     

尼龙6/蒙脱土纳米复合材料的结晶行为

用广角Ｘ 射线衍射（ＷＡＸＤ）、差示扫描量热仪（ＤＳＣ）、小角激光散射（ＳＡＬＳ）等手段研究了尼龙６／蒙脱土纳米复合材料的结晶行为．结果表明分散在尼龙６基体中的蒙脱土纳米粒子起成核剂的作用．蒙脱土的表面改性增加了蒙脱土和尼龙６分子之间的界面粘接，它具有阻碍尼龙６结晶的作用，使结晶活化能增加     

聚丙烯/蒙脱土纳米复合材料的等温结晶研究

采用差示扫描量热法 (DSC)对插层聚合法制备的聚丙烯 /蒙脱土纳米复合材料 (PP MMT)的等温结晶过程进行了研究 .引入蒙脱土 (MMT)后 ,PP MMT的结晶速率大幅度提高 ,相对结晶度略有下降 .采用Avrami方程对结晶动力学进行研究 ,Avrami指数n≈ 3 .0 ,半结晶时间t1 2 大幅度降低 .采用Hoffman理论计算了PP MMT的球晶生长的单位面积表面自由能σe,结果表明σe 随MMT含量的增加逐渐降低     

聚丙烯-g-聚氨酯共聚物的非等温结晶动力学研究

用DSC法研究了聚丙烯 (PP)和聚丙烯接枝聚氨酯的共聚物 (PP g PU)在不同冷却速率下的非等温结晶动力学 .用Avrami方程和莫志深改进法对DSC测定结果进行了处理 ,结果表明 ,PP g PU的动力学参数能很好的符合Avrami方程和莫志深改进方程 .PP接枝了聚氨酯支链后 ,结晶速率增大 ,球晶的生长和成核机制也相应发生改变 ,而其变化规律与接枝物的组成和结构密切相关     

Non‐isothermal crystallization kinetics and spherulitic morphology of nucleated poly(lactic acid): effect of dilithium cis‐4‐cyclohexene‐1,2‐dicarboxylate as a novel and efficient nucleating agent

The effect of dilithium cis‐4‐cyclohexene‐1,2‐dicarboxylate (CHDA‐Li) as a novel and efficient nucleating agent on the crystallization behaviors and spherulitic morphology of poly(lactic acid) (PLA) as well as non‐isothermal crystallization kinetics of the nucleated PLA was studied by means of differential scanning calorimetry and polarized light microscopy. The results show that CHDA‐Li serves as a good nucleating agent to accelerate the crystallization rate of PLA. The nucleation ability of CHDA‐Li is superior to octamethylenedicarboxylic dibenzoylhydrazide. With the incorporation of CHDA‐Li, the number of the spherulites increases, and the size decreases significantly. The non‐isothermal crystallization kinetics of the nucleated PLA can be well described by Jeziorny's and Mo's models. The activation energies (ΔE) of non‐isothermal crystallization were calculated by Kissinger's and Friedman's methods. The crystallization rate of PLA/0.5 wt% CHDA‐Li sample is faster than that of PLA/0.2 wt% CHDA‐Li sample, while the ΔE of the former is lower than that of the latter. Copyright © 2015 John Wiley & Sons, Ltd.     

茂金属聚乙烯的非等温结晶行为及其动力学研究

为探索分子量和支链含量对聚乙烯非等温结晶过程的影响,选用3组样品:(1)不同分子量的无支链线形聚乙烯;(2)低分子量的支链含量不同的试样;(3)高分子量的支链含量不同的试样.用DSC研究了这3组样品的非等温结晶动力学.结果表明:(1)与支链含量相比,分子量大小对结晶的影响是次要的,但高分子量样品的结晶度比低分子量样品低;(2)支链对聚乙烯的非等温结晶有重要影响,在支化聚乙烯中起决定作用;(3)无论是高分子量试样还是低分子量试样,支化含量增加,聚乙烯的结晶温度、结晶度、结晶动力学以及晶体的熔点等显著降低.     

反式-/顺式-1,4-聚异戊二烯共混体系的结晶动力学

采用差示扫描量热(DSC)法对反式-/顺式-1,4-聚异戊二烯共混体系的等温及非等温结晶动力学进行了研究,分别采用Avrami方程和莫志深法对其动力学参数进行了解析.研究结果表明,在反式-/顺式-1,4-聚异戊二烯共混体系的等温及非等温结晶过程中,顺式-1,4-聚异戊二烯(CPI)组分的存在会降低反式-1,4-聚异戊二烯(TPI)组分的结晶速率;在等温结晶过程中,CPI组分会提高TPI组分自身的结晶度;而非等温结晶过程中,CPI则提高了共混物中β晶型的相对含量.     

Isothermal crystallization kinetics of PP in PP/Mg(OH)2 composites

The crystallization and melting behavior of PP/Mg(OH)₂ composites was investigated, and the crystallization kinetic parameters and thermal characteristics were investigated according to the Avrami method. Optical polarizing microscope (POM) analysis suggested that the presence of Mg(OH)₂ particles gave rise to an increase in the number of nuclei and a decrease in PP spherulitic size. The Avrami exponent n of the PP and composites increased with increasing crystallization temperature, and markedly deceased with the addition of low Mg(OH)₂ content. A significant increase in crystallization kinetic constant, and a decrease in crystallization half time of PP were observed in the presence of Mg(OH)₂ particles, indicating a heterogeneous nucleating effect of Mg(OH)₂ upon crystallization of PP. The melting temperature and equilibrium melting temperature of PP in the composites decreased with increasing the Mg(OH)₂ content, which is directly related to the size of the PP crystals. The difference of PP melting enthalpies in the PP and composites demonstrated that the presence of Mg(OH)₂ can effectively enhance the crystalline of PP. The crystallization thermodynamics of PP and composites were studied according to the Hoffman theory. Surface free energy of PP chain folding for crystallization of PP/Mg(OH)₂ composites was lower than that of PP, confirming the heterogeneous nucleation effect of Mg(OH)₂. However, the evaluation of the nucleation activation energy of PP suggested the presence of a large amount of Mg(OH)₂ particles in the PP matrix reduced the mobility of PP segments and restricted the development of PP nucleation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1914–1923, 2005     

Studies on the Crystallization Behavior of Polypropylene Solid Phase Grafted Maleic Anhydride

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分子量对聚丙烯等温结晶的影响

<正> 在高聚物结晶动力学的研究中,分子量对结晶速率的影响是一个有实际意义和理论兴趣的研究课题,由于聚烯烃可以得到分子量变化范围相当宽(MW从10~3到10~6)的试样,因而它是研究结晶速率分子量依赖性较合适的对象,其中研究最多的是聚乙烯和聚丙烯。从前入的研究报道看来,影响聚丙烯结晶速率的因素比聚乙烯要复杂。除了聚丙烯可生成多种晶型结构,会影响其结晶速率以外,用不同聚合方法制备的试样,由于其链结     

Kinetics of Nonisothermal and Isothermal Crystallization of Metallocene Polyethylene

Thedevelopmentofmetallocenecatalystsundoubtedlyrepresentsarevolutioninthepolyolefinbusiness.MetallocenePE(MPE)coverspolyethyleneswhichareproducedbymetallocenecatalysttechnology.EXXONChemicalCo.developedanewmeta-llocenepolyethylene-EXCEED'"PEin1991.Nowmoreandmoreeffortsarespentonthisinterestingproject.Uniformmolecularstructureandnarrowmoleculardistribution,makeMPEbetterphysicalpropertiesthanthoseofconventionalPE,andalsomakeitlowmeltstrengthandbadprocessability.Sotherelationshipbetween…     

Crystallization behavior of polypropylene with or without sodium benzoate as a nucleating agent

The crystallization kinetics of polypropylene (PP) with or without sodium benzoate as a nucleating agent were investigated by means of DSC and polarized optical microscopy in isothermal and nonisothermal modes. A modified Avrami equation was applied to the kinetic analysis of isothermal crystallization. The addition of the nucleating agent up to its saturation concentration increased the crystallization temperature by 15 °C and shortened both the isothermal and nonisothermal crystallization half‐times. It was concluded that the sodium benzoate acted as a good nucleating agent for α‐form PP. By adding the nuclefier to PP, adequately controlled spherulites increased the mechanical properties including especially the Izod impact strength and shortened cycle time of PP. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1001–1016, 2001