石墨烯/聚丙烯复合材料的等温结晶动力学研究

采用差示扫描量热仪(DSC)研究了石墨烯(RGO)/聚丙烯(PP)复合材料的等温结晶行为。结果表明:对于纯PP和RGO/PP复合材料,结晶温度(Tc)的提高将导致结晶速率(G1/2)变慢、绝对结晶度(Xc)提高;PP和RGO/PP复合材料的等温结晶在相当大的范围内符合Avrami方程;同纯PP相比,RGO/PP复合材料的G1/2相对增加,而结晶活化能相对减小,这意味着RGO对PP起到了外加成核剂的作用,促进了PP的结晶。     

低密度聚乙烯/石墨烯纳米复合材料非等温结晶动力学

采用差示扫描量热仪研究了不同石墨烯(GP)含量的低密度聚乙烯(PE–LD)纳米复合材料在不同降温速率下的非等温结晶行为。结果表明,不同含量GP填料的加入均导致PE–LD结晶温度提高,表明GP填料对PE–LD基体起到异相成核作用;莫志深法能很好地描述纳米复合材料的动态结晶行为。动力学数据显示,当GP质量分数为0.5%和2%时,PE–LD复合材料的整体结晶速率、活化能、成核常数和生长晶面的表面自由能均比纯PE–LD低,而含量为5%时其值均比纯PE–LD高,因此适量的GP有利于PE–LD的结晶。由成核常数、表面自由能值可看出低含量GP促进PE–LD晶粒的二次成核、生长,而高含量GP则抑制晶粒二次成核、生长。     

赤泥/聚丙烯复合材料非等温结晶动力学研究

采用DSC研究了聚丙烯(PP)及聚丙烯/赤泥复合材料的非等温结晶动力学,对所得的数据采用了Avrami方程的Jeziorny法及Mo法进行处理.结果表明:赤泥的加入提高了PP的结晶温度和结晶速率,PP的结晶活化能降低,赤泥成核活性高于改性的赤泥.在同样含量下,经钛酸酯偶联剂改性的赤泥使PP结晶温度增加,结晶活化能与赤泥/聚丙烯复合材料相比有小幅的增加.赤泥具有异相成核作用,经表面修饰的赤泥异相成核效果降低.     

聚丙烯/氢氧化镁复合材料非等温结晶动力学的研究

通过差示扫描量热仪,采用修正的Avrami方程研究了硅烷改性氢氧化镁对聚丙烯非等温结晶行为的影响,并采用Kissinger方法比较了复合材料和聚丙烯的结晶活化能。结果表明,氢氧化镁在聚丙烯非等温结晶过程中起到异相成核作用,提高了聚丙烯的结晶速率,并降低了材料的结晶活化能。     

聚乙二醇对聚丙烯复合材料非等温结晶动力学的影响

利用差示扫描量热仪(DSC)研究了聚乙二醇(PEG)对聚丙烯复合材料非等温结晶行为的影响,并采用Jeziorny法和Mo法分析了复合材料的非等温结晶曲线。结果表明:PEG的添加降低了聚丙烯复合材料的结晶温度,对聚丙烯结晶的成核及晶体生长均产生一定影响。当PEG用量由0增至5份时,复合材料的结晶峰温度和初始结晶温度降低,结晶速率增大。     

PP/CNTs复合材料的非等温结晶动力学研究

对碳纳米管进行表面处理,利用熔融共混法制备聚丙烯/碳纳米管复合材料,经过粉碎压片后,得到样品.通过SEM观察聚丙烯/碳纳米管复合材料的断面结构.通过DSC研究聚丙烯/碳纳米管复合材料的非等温结晶过程.结果表明,经表面修饰的碳纳米管能够均匀分散于聚丙烯基体中,二者界面结合紧密;加入微量的碳纳米管就可以明显地提高复合材料的结晶温度和结晶速率.     

聚丙烯／滑石粉复合材料的等温结晶动力学

用差示扫描量热法(DSC)研究聚丙烯(PP)及PP／滑石粉复合材料的等温结晶过程。用Avrami方程全面分析PP／滑石粉的等温结晶动力学，并由此获得相关的动力学参数；用Kissinger方程研究滑石粉对PP／滑石粉复合材料结晶活化能的影响。研究表明：加入滑石粉后明显提高PP／滑石粉复合材料的结晶速率和结晶度；证明滑石粉能促进PP材料的结晶，并在PP结晶过程中起到异相成核作用。PP／滑石粉复合材料的等温结晶过程属于典型的异相成核机理。     

纳米Al2O3改性聚丙烯的非等温结晶动力学

采用差示扫描量热法研究了聚丙烯(PP)及PP/纳米Al_2O_3复合材料的非等温结晶动力学。结果表明:纳米Al_2O_3有异相成核的作用,使PP的结晶峰温升高;PP的半结晶时间随纳米Al_2O_3含量增大而减小;纳米粒子的填充使PP的结晶活化能(△E)增大,含纳米Al_2O_3质量分数为2%的PP的△E最大。     

β晶聚丙烯非等温结晶动力学的研究

利用差示扫描量热法（DSC）研究了聚丙烯在加入稀土类β晶成核剂前后形成的α晶聚丙烯和β晶聚丙烯的非等温结晶行为，发现该成核剂能诱导生成高含量β晶型，当其含量为0．1％（质量分数，下同）时，β晶型含量大于90％。采用Jeziorny法和莫志深法对DSC数据进行处理后发现，该成核剂的加入虽然降低了结晶速率，但使结晶温度得到大幅度提高，是一种有效的成核剂。     

无规抗冲共聚聚丙烯的非等温结晶动力学

在Spheripol工艺中试装置上制备了丙丁无规抗冲共聚聚丙烯（记作PP-1）和乙丙丁无规抗冲共聚聚丙烯（记作PP-2）,对两种聚丙烯的非等温结晶行为进行了研究,针对无规抗冲共聚聚丙烯实际生产过程中的结晶特点,分别结合Caze法和Mo法提出的理论对非等温结晶动力学Ozawa模型进行了修正。结果表明：采用修正过的两种方法更加符合无规抗冲共聚聚丙烯实际生产过程中的非等温结晶行为。采用Caze法修正Ozawa模型后求出的PP-1和PP-2的Avrami指数分别为2.44,2.37,说明乙烯单体的引入并不会使PP-1的成核机理和生长方式发生改变。采用Mo法修正Ozawa模型后求出的动力学参数F(T)在同一相对结晶度下PP-1小于PP-2,表明在同一时间内PP-2要达到某一结晶度所需冷却速率更大;采用Kissinger法计算的PP-1和PP-2的结晶活化能分别为11.12,14.14 kJ/mol,进一步证实了上述结果。     

PP/碳纳米管复合材料的结晶动力学研究

采用原子转移自由基(ATRP)活性聚合方法在多壁碳纳米管(MWNT)表面接枝丙烯酸丁酯聚合物(PBA),并以接枝聚合物MWNT-PBA对聚丙烯(PP)进行改性。红外光谱(FT-IR)及透射电子显微镜(TEM)测试结果表明,采用ATRP法成功地将PBA接枝到MWNT表面上。利用差示扫描量热仪(DSC)对PP/MWNT复合材料的非等温结晶动力学进行了研究。结果表明,PP/MWNT复合材料中由于MWNT的加入明显地提高了复合材料的结晶温度和结晶速率,并降低了结晶活化能。MWNT-PBA和MWNT-COOH(酸化MWNT)加入PP都有异相成核的作用,而MWNT-PBA比MWNT-COOH的作用更加明显。     

聚酰胺11/白炭黑纳米复合材料的非等温结晶动力学研究

采用原位聚合法制备了聚酰胺11（PA11）及PA11/白炭黑纳米复合材料,利用差示扫描量热仪研究了PA11及其纳米复合材料的非等温结晶过程,用经Jeziorny修正的Avrami方程、Mo法对其非等温结晶动力学进行了研究,计算并得到了非等温结晶动力学参数。结果表明,Avrami方程和Mo法都适用于处理PA11及其纳米复合材料的非等温结晶过程;在其非等温结晶过程中,PA11及其纳米复合材料都包括初期结晶和二次结晶两个阶段;Mo法表明,复合材料的结晶速率比PA11的小。此外,用Huffman-Lauritzen理论计算了PA11及其纳米复合材料非等温结晶的结晶活化能,结果表明,纳米复合材料的结晶活化能的绝对值小于PA11。     

Nonisothermal Crystallization and Melting Behaviors of PP/PA6/TiO2 Nanocomposites

Titanium dioxide nanoparticles were functionalized with toluene-2,4-diisocyanate and then polypropylene/polyamide 6 blends containing functionalized titanium dioxide were prepared using a twin-screw extruder. The nonisothermal crystallization and melting behaviors of the as-prepared nanocomposites were investigated using differential scanning calorimetry. The nonisothermal crystallization differential scanning calorimetry data were analyzed by the modified-Avrami (Jeziorny) and combination of Ozawa and Avrami (Mo) methods. It can be found that the Jeziorny method can be used to describe the main crystallization process, and the Mo method can better deal with nonisothermal crystallization kinetics of the polypropylene and polyamide 6 phase in polypropylene/polyamide 6-based nanocomposites. The nonisothermal crystallization analysis shows that the titanium dioxide nanoparticles have two effects on polypropylene/polyamide 6 blends, i.e., it can favor the improvement of crystallization ability and decrease the crystallization rate of the polypropylene and polyamide 6 phase in polypropylene/polyamide 6-based nanocomposites. For one thing, the functionalized titanium dioxide nanoparticles in the polypropylene/polyamide 6-based nanocomposites act as effective nucleation agents and result in higher crystallization temperature (T₀) than that of the polypropylene and polyamide 6 in pure polypropylene/polyamide 6 blends, which indicated titanium dioxide nanoparticles favor the improvement of crystallization ability of the polypropylene and polyamide 6 phase. For another, the existence of functionalized titanium dioxide nanoparticles hinders the free movement of polymer chains and results in lower crystallinity than that of the polypropylene and polyamide 6 in pure polypropylene/polyamide 6 blends, which indicated titanium dioxide nanoparticles decrease the crystallization rate of the polypropylene and polyamide 6 phase in polypropylene/polyamide 6-based nanocomposites. The nonisothermal crystallization melting behaviors show that there is single or double melting peak, which varies with different cooling rates for the polyamide 6 phase in polypropylene/polyamide 6-based nanocomposites. Multiple melting peak is mainly caused by the different crystalline structure of the polyamide 6 phase, the melting peak I is mainly caused by γ crystal of the polyamide 6 phase, while the melting peak II corresponds to the thermodynamic stability of α crystal. Besides, the recrystallization of the polyamide 6 phase in the heating process, and the effect of the incorporation of the titanium dioxide nanoparticles may have some contributions to the appeared multiple melting peak of the polyamide 6 phase in the polypropylene/polyamide 6-based nanocomposites.     

PP/PP-g-MAH/HGB复合材料非等温结晶行为研究

采用熔融法制备了聚丙烯/马来酸酐接枝聚丙烯/空心玻璃微珠（PP/PP-g-MAH/HGB）复合材料,采用差示扫描量热仪研究了PP、PP/HGB、PP/PP-g-MAH/HGB复合材料的非等温结晶过程,并通过Jeziorny法和Mo法研究了3种材料的非等温结晶动力学。结果表明,随着降温速率的增大,3种材料的结晶峰温、结晶起始温度和结晶度均减小,结晶速率增大;HGB抑制了PP的结晶行为,降低了结晶速率;PP-g-MAH对PP结晶速率的影响较小,HGB和PP-g-MAH都会改变PP的结晶成核和生长机理。     

聚丙烯/碱式硫酸镁晶须复合材料等温结晶动力学研究

采用月桂酸(LA)对碱式硫酸镁晶须(MOSw)进行改性,将改性产物LA-MOSw与聚丙烯(PP)熔融共混制成复合材料。利用差示扫描量热法(DSC)考察了纯PP及PP/MOSw、PP/LA-MOSw复合材料的等温结晶行为,并进一步通过Avrami方程计算得到相关等温结晶动力学参数。结果表明:在相同结晶温度下,PP/LAMOSw复合材料具有较短的半结晶时间(t_(1/2))及较小的Avrami指数(n),说明加入LA-MOSw能促进PP基体结晶,生成更多二维盘状结晶;但MOSw的加入则会抑制PP的结晶,而诱导生成更多的三维球状结晶。Arrhenius方程及Hoffman-Lauritzen模型分析结果表明,LA-MOSw促进PP结晶的原因主要在于LAMOSw的引入降低了PP基体的结晶活化能(ΔE)与成核参数(K_t),使PP基体成核结晶变得更加容易。     

Nonisothermal Crystallization Kinetics of Polypropylene/Polyethersulfone Blend

The nonisothermal crystallization kinetics of PP and PP/PES (80/20 wt%) blend was investigated by using differential scanning calorimetry (DSC). It was observed that the crystallization peak temperature (T_p) and the half time (t _1/2) of crystallization of PP/PES blend are slightly but consistently lower than those of PP at various cooling rates. The nonisothermal crystallization data were analyzed by using Avrami equation, Ozawa and Mo method. The validity of the different kinetics models to the nonisothermal crystallization process of two samples is discussed. The Mo method can successfully explain the overall nonisothermal crystallization process of PP and PP/PES blend. The activation energy (ΔE) for nonisothermal crystallization of PP and PP/PES blend is determined by using the Kissinger method. The result shows that the ΔE value of PP is slightly higher than that of PP/PES blend.     

Nonisothermal Crystallization and Melting Behavior of EVA/OMWNTs Nanocomposites

EVA/OMWNTs nanocomposites have been successfully prepared by a simple melt compounding method. The nonisothermal crystallization behaviors of the EVA/OMWNTs nanocomposites are strongly dependent on the degree of crystallinity (X_c), peak crystallization temperature (T_p), half-time of crystallization (t_1/2), and Avrami exponent (n) on the OMWNTs content and cooling rate. The dependence of the crystallization activity energy on the extent of relative crystallization for the plain EVA and the EVA/OMWNTs nanocomposites shows that ΔE increases with the increase in the relative degree of crystallinity below about 5%, and the ΔE decreased when the relative degree of crystallinity was greater than about 5%.     

HDPE/GF的力学性能及非等温结晶行为研究

采用双螺杆挤出机制备了高密度聚乙烯（HDPE）／玻纤（GF）复合材料,并对HDPE／GF复合材料的力学性能和非等温结晶行为进行了研究。结果表明．MAH-g-POE可以提高复合材料的冲击强度,复合材料中玻纤与HDPE的界面粘结状况良好;复合材料的Avrami指数（n）不随冷却速率改变而改变。     

TPV及其微发泡复合材料的非等温结晶动力学研究

以热膨胀发泡微球为发泡剂,采用双螺杆挤出机及模压法制备了微发泡三元乙丙橡胶(EPDM)/聚丙烯(PP)复合材料。利用差示扫描量热法(DSC)研究了该热塑性硫化胶(TPV)及其微发泡复合材料的非等温结晶动力学。结果表明:TPV及其发泡复合材料的非等温结晶过程与Ozawa动力学方程不符,但可用Jeziorny和莫志深(Mo)动力学方程描述。微发泡复合材料的起始结晶温度、最大结晶温度在同一降温速率下均比相应的TPV高,这表明发泡微球具有一定的成核作用;另外,表征结晶速率的半结晶时间(t1/2)明显延长,说明发泡微球的加入对TPV结晶有一定的延缓作用,而复合物较大的空间体积结构所导致的位阻效应是延缓TPV结晶的主要原因。