PP/PP-g-NH2/纳米SiO2复合材料的非等温结晶

采用示差扫描量热法（DSC）研究了聚丙烯/氨基化聚丙烯/纳米二氧化硅（PP/PP-g-NH₂/SiO₂）复合材料的非等温结晶行为。利用Caze法对结晶动力学进行了分析,Avrami指数n表明纳米SiO₂和PP-g-NH₂的加入改变了PP的结晶成核和生长机理;运用Dobreva法研究了纳米粒子的成核活性,结果表明纳米SiO₂成核活性差,增容剂PP-g-NH₂明显增强其成核活性;采用Friedman法分析了复合材料的结晶有效能垒,研究表明加入纳米SiO₂使PP的结晶有效能垒降低,添加PP-g-NH₂则进一步降低复合体系的结晶有效能垒;当纳米粒子含量为3%时,添加5% PP-g-NH₂能有效提高纳米粒子成核活性,降低复合材料结晶有效能垒。     

PP/纳米SiO2复合材料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）/纳米SiO2复合材料的非等温结晶动力学,研究了纳米粒子的成核活性及复合材料的结晶有效能垒。研究结果表明,纳米SiO2起到异相成核的作用,使PP的结晶峰温升高,结晶总速率增大;增容剂马来酸酐接枝聚丙烯(PP-g-MAH)提高了纳米SiO2的成核活性;添加纳米SiO2使复合材料的结晶有效能垒降低,PP-g-MAH使复合材料的结晶有效能垒增大,但低于纯PP的结晶有效能垒。     

SiO2-g-PS纳米微球的制备及其在增韧PP中的应用

采用乳液聚合方法在纳米SiO₂粒子表面接枝苯乙烯（St）单体,制备了具有核/壳结构的SiO₂-g-PS纳米微球,用FTIR、TEM、XPS和TG分析了SiO₂-g-PS的结构。结果表明,乳液聚合产物基本呈球形、SiO₂为核、PS为壳的核壳结构。通过熔融共混工艺制备聚丙烯（PP）基复合材料,并对其力学性能进行了分析,结果表明,当SiO₂-g-PS填充量较低［4%～6％（质量）］时,SiO₂-g-PS/PP复合材料的冲击强度和拉伸强度明显提高,并对PP的结晶有明显的异相成核作用。     

PBT /纳米SiO2非等温结晶动力学研究

熔融制备了PBT/纳米SiO₂复合材料,用DSC分别研究了SiO₂在低含量(0.3%质量分数)和高含量(3%)时的非等温结晶行为;并分析了PBT/纳米SiO₂复合材料的结晶动力学。结果表明,纳米SiO₂对PBT有异相成核作用,加入纳米SiO₂后,显著提高了PBT结晶温度,加快了其结晶速率。结晶动力学表明,莫志深法很好的吻合了PBT/纳米SiO₂复合材料体系,而Ozawa方法并不太适合。通过结晶活化能的计算,表明在低含量(0.3%)时有更好的结晶能力。     

PP/纳米Dy_2O_3复合材料的非等温结晶

用溶液法制备了聚丙烯(PP)/纳米三氧化二镝(Dy_2O_3)复合材料,用差示扫描量热法研究了PP/纳米Dy_2O_3复合材料的非等温结晶行为,采用Caze法和莫志深法对其结晶动力学进行了分析,研究了纳米粒子的成核效率和成核活性。结果表明:纳米Dy_2O_3提高了PP的结晶峰温和结晶速率,使结晶活化能增大;w(Dy_2O_3)为2%的纳米粒子成核效率最高,w(Dy_2O_3)为5%的纳米粒子成核活性最低。     

原位聚合制备SiO2高含量PA6/SiO2母料及其复合材料

采用溶剂转移法对二氧化硅(SiO₂)进行改性处理,并通过原位聚合方法制备了高含量聚酰胺6(PA6)/ SiO₂母料,并通过母料与外购纯PA6共混制备了纳米复合材料。通过X-射线衍射、透射电镜(TEM)等仪器分别对PA6/SiO₂纳米复合材料的结晶及晶型结构、微观分散形态进行了表征;并对纳米复合材料的力学性能等进行了测试。结果表明,改性后的SiO₂在PA6原位聚合体系中分散均匀且能够达到纳米级的分散效果,并会起到异相成核剂的作用。通过母料与纯PA6共混制备的SiO₂纳米复合材料与传统熔融法相比拉伸强度提高了12.17%,断裂伸长率提高了37.30%,缺口冲击强度提高了37.25%。     

PP-g-MAH对PP/纳米SiO_2复合材料性能的影响

采用熔融共混法制备了聚丙烯(PP)/纳米SiO2复合材料,研究了相容剂马来酸酐接枝聚丙烯(PP-g-MAH)对复合材料力学性能、结晶性能及界面作用的影响。结果表明:PP-g-MAH能有效地增强纳米SiO2与PP基体间的界面作用,提高复合材料的力学性能;同时,PP-g-MAH增强了纳米SiO2的成核活性,使PP的结晶温度升高,球晶细化。     

反应性增容对PP/纳米SiO2中填料成核活性的影响

采用示差扫描量热法研究PP/纳米二氧化硅(SiO2)复合材料的非等温结晶动力学.研究结果表明:纳米SiO2起到异相成核的作用,使PP的结晶峰温升高;反应性增容增强了纳米SiO2的威核活性;添加纳米SiO2使PP的结晶活化能增大,反应性增容使复合材料的结晶活化能减小,与纯PP的结晶活化能相近;但反应性增容使PP的结晶总速率小于未增容填充体系.     

聚丙烯/石墨烯纳米复合材料的非等温结晶动力学研究

通过液相共混法制备了聚丙烯/石墨烯(PP/RGO)纳米复合材料,利用差示扫描量热仪(DSC)探讨了非等温条件下的PP/RGO复合材料的结晶动力学。结果表明:快速冷却以及引入RGO均能促进复合材料的结晶;RGO的加入同时提高了复合材料中PP的结晶速率和绝对结晶度,并降低了PP的结晶活化能,这说明RGO起到了成核剂的作用,促进了PP的结晶;另外,采用Ozawa法和莫志深(Mo)法修正的Avrami方程均可较好地描述纯PP和PP/RGO的非等温结晶过程。     

PP/POE-g-GMA/纳米SiO2复合材料性能研究

采用熔融共混法制备了聚丙烯/甲基丙烯酸缩水甘油酯接枝POE/纳米二氧化硅(PP/POE-g-GMA/纳米SiO2)复合材料,研究了材料的力学性能、动态力学性能与结晶性能.结果表明:5%的POE-g-GMA和3%的氨基功能化纳米SiO2(SiO2-g-NH2)具有明显的协同增韧效应,冲击强度提高157%,使PP出现较大的低温损耗模量峰和内耗峰;POE-g-GMA和纳米SiO2对PP的结晶均有促进作用,SiO2-g-NH2的异相成核作用更明显;POE-g-GMA能诱导PPβ晶的形成,添加纳米SiO2使β晶含量降低.     

NONISOTHERMAL CRYSTALLIZATION KINETICS AND MECHANICAL PROPERTIES OF PP/NANO-SiO2 COMPOSITES

The nonisothermal crystallization kinetics of polypropylene (PP)/nano-SiO₂ composites was studied by means of differential scanning calorimetry (DSC). The modified Avrami theories by Jeziorny, Ozawa, and Mo were used to analyze the data of DSC. The results showed that both the Jeziorny and Mo methods could describe this system very well, but the Ozawa analysis failed. The activation energy was evaluated by the Kissinger method. It was found that the crystallization activation energy of PP was higher than that of PP/nano-SiO₂ composites. The determined results of mechanical properties showed that the addition of nano-SiO₂ increased the mechanical properties of the PP. Micrographs of Polarized optical micrograph (POM) further demonstrated that nano-SiO₂ could toughen the PP.     

纳米二氧化硅复合涂料的制备及其性能

通过表面改性技术制备了疏水性的纳米二氧化硅粒子,粒径约50 nm.在机械搅拌和超声场共同作用下,将纳米二氧化硅均匀分散到聚氨酯清漆中,制得纳米二氧化硅复合涂料,考察了纳米二氧化硅复合量对复合涂料性能的影响.直接腐蚀实验、阳极极化和交流阻抗测试结果表明,加入偶联剂改性的纳米二氧化硅后,复合聚氨酯清漆在氯化钠溶液中的抗腐蚀能力明显提高,浸泡腐蚀失重量减小约20％～70％,阳极腐蚀电流降低1个数量级以上,低频区涂层阻抗值增大2个数量级以上.油漆剪切强度和剥离强度实验显示,纳米复合漆膜的附着力增加.     

溶胶-凝胶法制备PET/SiO2纳米复合材料及其TG、DSC分析

采用溶胶-凝胶（sol-gel）法，将正硅酸乙酯和水加入到制备聚对苯二甲酸乙二酯（PET）的中间产物对苯二甲酸双羟乙酯(BHET)中,在液态下均匀混合，高温下快速发生溶胶-凝胶反应，再按PET缩聚反应制得PET/SiO₂纳米复合材料。通过TEM、TG、DSC对材料进行了表征和研究。结果表明，SiO₂在PET中均匀分散，其尺寸在10～100 nm之间，PET/SiO₂纳米复合材料的热降解活化能较普通PET有明显提高，但初始降解温度和结晶性能均有所降低。     

Nonisothermal crystallization of PP/nano‐SiO2 composites

The kinetics of nonisothermal crystallization of polypropylene (PP) containing nanoparticles of silicon dioxide (SiO₂) were investigated by differential scanning calorimetry (DSC) at various cooling rates. Several different analysis methods were used to describe the process of nonisothermal crystallization. The results showed that the Ozawa equation and Mo's treatment could describe the nonisothermal crystallization of the composites very well. The nano‐SiO₂ particles have a remarkable heterogeneous nucleation effect in the PP matrix. The rate of crystallization of PP/nano‐SiO₂ is higher than that of pure PP. By using a method proposed by Kissinger, activation energies have been evaluated to be 262.1, 226.5, 249.5, and 250.1 kJ/mol for nonisothermal crystallization of pure PP and PP/nano‐SiO₂ composites with various SiO₂ loadings of 1, 3, and 5%, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1013–1019, 2004     

Nonisothermal crystallization behavior of highly exfoliated polypropylene/clay nanocomposites prepared by in situ polymerization

Polypropylene/clay nanocomposites (PPCNs) were prepared via an in situ polymerization method with a Ziegler–Natta/clay compound catalyst in which the MgCl₂/TiCl₄ catalyst was embedded in the clay galleries. The wide‐angle X‐ray diffraction and transmission electron microscopy results showed that the clay particles were highly exfoliated in the polypropylene (PP) matrix. The nonisothermal crystallization kinetics of these PPCNs were investigated by differential scanning calorimetry at various cooling rates. The nucleation activity were calculated by Dobreva's method to demonstrate that the highly dispersed silicate layers acted as effective nucleating agents. The Avrami, Jeziorny, Ozawa, and Mo methods were used to describe the nonisothermal crystallization behavior of the PP and PPCNs. Various parameters of nonisothermal crystallization, such as the crystallization half‐time, crystallization rate constant, and the kinetic parameter F(t), reflected that the highly exfoliated silicate layers significantly accelerated the crystallization process because of its outstanding nucleation effect. The activation energy values of the PP and PPCNs determined by the Kissinger method increased with the addition of the nanosilicate layers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

火焰喷涂聚酰胺12/n-SiO2复合涂层工艺及性能

采用火焰喷涂法制备了聚酰胺12 (PA12)及聚酰胺12/纳米SiO₂ (n-SiO₂)复合涂层,并利用电子拉力机、摩擦磨损试验机、红外光谱仪（FTIR）和示差扫描量热仪（DSC）等对涂层的结构与性能进行了研究。红外光谱分析表明PA12及PA12/ n-SiO₂粉末在火焰喷涂过程中没有发生氧化或降解反应,表明火焰喷涂法适宜制备PA12及PA12/n-SiO2复合涂层;DSC分析结果表明n-SiO₂具有成核剂作用,能提高PA12大分子的结晶速度及结晶度;涂层力学性能及摩擦磨损性能分析表明n-SiO₂能提高涂层的力学性能,改善涂层的耐老化性能和摩擦磨损性能。当n-SiO₂添加量为1.5%（质量）时,涂层综合性能最佳。