硅烷偶联剂复合改性蒙脱土制备NR/OMMT纳米复合材料

采用硅烷偶联剂和十六烷基三甲基溴化铵(CTAB)作为复合改性剂制备有机蒙脱土,使有机蒙脱土的结构发生了改变.其中采用硅烷偶联剂KH570与CTAB复合改性的效果较好,得到了插层效果较好的NR/OMMT纳米复合材料.     

有机改性蒙脱土制备聚酰胺6/蒙脱土复合材料

采用有机复合改性的方法制备了改性蒙脱土,并采用原位聚合方法制备了尼龙-6/蒙脱土复合材料,利用FTIR、TG-DTA、XRD对有机蒙脱土进行了表征。结果表明,有机插层剂已进入蒙脱土的层间,使蒙脱土的层间距由原来的1.39 nm增大到2.32 nm,从而改善了它的分散性以及与尼龙-6之间的粘结作用,二者构成的纳米复合材料具有很好的力学性能。当加入2%的有机蒙脱土时,拉伸强度提高16%,冲击强度提高5%。     

双子阳离子表面活性剂改性蒙脱土的制备与表征

合成了新型双子阳离子表面活性剂Gemini-16,并用其对钠基蒙脱土进行改性。红外光谱(FTIR)、热重(TGA)分析表明,Gemini-16已插层到蒙脱土片层间。X射线衍射(XRD)表明,改性后蒙脱土层间距从1.47 nm增加到3.48 nm。分散性实验表明,经Gemini-16改性的蒙脱土在液体石蜡中表现出很好的相容性和分散性,改性效果优于目前常用的CTAB处理效果,更有利于聚合物单体进入蒙脱土层间形成聚合物/蒙脱土纳米复合材料。     

硅烷偶联剂对OMMT/NR纳米复合材料结构与性能的影响

采用混炼插层法制备有机蒙脱土(OMMT)/NR纳米复合材料,研究硅烷偶联剂对其结构和性能的影响.结果表明,与NR相比,OMMT/NR纳米复合材料的物理性能,热稳定性和动态力学性能均有所提高;采用硅烷偶联剂KH-560改性的OMMT制备的纳米复合材料各项性能均优于采用硅烷偶联剂KH-550改性的OMMT制备的纳米复合材料.     

硅烷偶联剂接枝改性蒙脱土对PBT性能的影响

选用硅烷偶联剂(KH560)对钠基蒙脱土进行改性。采用熔融共混法制备了不同类型的蒙脱土/聚对苯二甲酸丁二醇酯(PBT)纳米复合材料,通过X射线衍射、透射电镜、动态热力学测试等手段考察了不同类型的蒙脱土对复合材料结构和性能的影响。硅烷偶联剂接枝改性蒙脱土后,蒙脱土/PBT复合材料中蒙脱土层间距从1.26 nm增加到1.42 nm,且蒙脱土在聚合物基体中的团聚现象明显改善。与未改性蒙脱土和商品化有机改性蒙脱土相比较,硅烷偶联剂改性蒙脱土/PBT复合材料的拉伸强度和缺口冲击强度提高。     

二聚阳离子表面活性剂改性蒙脱土的制备和表征

合成了二聚阳离子表面活性剂GeminiC12,用核磁共振氢谱(1HNMR)表征了它的结构,并用它作为有机插层剂应用于蒙脱土的改性处理。红外光谱(FTIR)、热重分析(TGA)表明,GeminiC12已插层到蒙脱土片层间。X射线粉末衍射(XRD)表明,插层后蒙脱土层间距从1 19nm增加到3 8nm,是十六烷基三甲基溴化铵(CTAB)处理效果的两倍。沉降实验表明,改性后蒙脱土在苯乙烯和石蜡中形成凝胶体系,表现出很好的相容性和分散性,这种改性效果优于目前常用的CTAB处理效果,更有利于聚合物或其单体进入蒙脱土层间形成纳米复合材料。     

新型超分散有机蒙脱土的制备和表征

采用十六烷基三甲基溴化铵为插层剂,通过先机械搅拌后超声振荡的复合工艺对钠基蒙脱土进行了有机改性,制备了超分散蒙脱土并对其进行了表征.FTIR表明有机插层剂进入蒙脱土层间;XRD结果表明超分散蒙脱土层间距由改性前的1.01 nm增加到3.13 nm;SEM和TEM表明蒙脱土已被剥离成单个片层.粒径分析表明超分散蒙脱土有很好的亲油性和分散性;沉降对比实验说明超分散蒙脱土分散性好,可长时间悬浮在熔融己内酰胺中.     

复合插层有机蒙脱土的制备及表征

以钠基蒙脱土、十六烷基三甲基溴化铵(CTAB)和己内酰胺为原料,制备了复合插层有机蒙脱土。红外光谱分析(IR)、热重分析(TGA)和X-射线衍射分析(XRD)表明,有机插层剂已进入蒙脱土的层间,CTAB/己内酰胺复合插层有机蒙脱土的层间距大于单阳离子CTAB插层有机蒙脱土的层间距。Molau实验结果表明,这种有机蒙脱土在有机介质中表现出很好的分散性。     

不同钠盐改性蒙脱土的制备及表征

为了后期制备有机改性蒙脱土,利用离子交换法将氯化钠、硫酸钠和碳酸钠三种钠盐表面活性剂插入到天然蒙脱土(MMT)层间,对其进行钠基化处理,并对改性后的蒙脱土结构和性能进行了表征。热重分析(TGA)结果表明,钠盐已成功插层到蒙脱土层间,改性后的蒙脱土热稳定性增强;X-射线衍射分析(XRD)结果表明,改性后的蒙脱土层间距增大,平均层间距分别从0.99 nm增大到1.25、1.23、1.21 nm,其中氯化钠改性效果最好。     

天然钙蒙脱土的钠化改型和有机化改性

用碳酸钠作为钠化剂对天然钙蒙脱土进行了钠化改型,用CTAC、CTAB、C18三种插层剂分别对钠蒙脱土进行了有机插层改性。对钠化改型前后的蒙脱土进行了XRD、FTIR分析,对有机改性前后的蒙脱土用XRD、SEM、FTIR和TG-DTA等进行了表征和分析。结果表明:钙蒙脱土经钠化改型后,层间距增大,结晶度变差,活性增强;CTAC、CTAB、C18三种改性剂都能使蒙脱土的晶层间距有较大提高,其中,尤以C18改性剂的有机化效果最为显著;蒙脱土有机改性前后外观变化十分显著;有机改性蒙脱土的结构水无明显变化,层间吸附水显著减少,疏水的有机插层剂主要进入蒙脱土层间,大量脱去层间吸附的水分子,对晶体结构本身并无影响。有机改性后,蒙脱土的吸附水与层间水的脱水温度与脱水量均显著降低,有机插层剂的大量插入,改变了原土的亲水性使之变为疏水,并提高了其热稳定性。     

γ-氨丙基二甲基乙氧基硅烷修饰蒙脱土及硅烷化蒙脱土的性能

用单官能团硅烷偶联剂γ-氨丙基二甲基乙氧基硅烷（APMS）修饰蒙脱土（MMT）, IR 分析表明APMS通过化学键与蒙脱土键合。利用偶联剂上的氨基与水杨醛显色生成黄色希夫碱对404 nm处可见光的吸收特性进行定量测试,确定了蒙脱土可和偶联剂反应的活性硅羟基数目为29.6 mmol/(100gMMT),最佳烘干温度为120 ℃。XRD结果说明蒙脱土的活性硅羟基分布在其端面不是在层间。推断出蒙脱土和单官能团硅烷偶联剂的反应分两步进行：偶联剂的烷氧基先在水醇溶液中水解生成硅醇,然后和蒙脱土端面上的硅羟基高温干燥脱水形成硅烷化蒙脱土。偶联剂修饰蒙脱土后其阳离子交换容量（CEC）不变,分散性实验显示硅烷化蒙脱土在水中的分散性变差,在甲苯和乙醇中的分散性提高,说明偶联剂的修饰提高了MMT在有机溶剂中的分散性。     

Characteristics of nitrile–butadiene rubber layered silicate nanocomposites with silane coupling agent

Nanocomposites of organophilic montmorillonite (C18‐MMT), nitrile–butadiene rubber (NBR), and a coupling agent were produced during a melt compounding process at room temperature. During the process, it was clearly observed that organo‐MMT particles were exfoliated into nanoscale layers of approximately 1–30 nm thickness, in addition to their original 40 μm thickness. These MMT layers were uniformly dispersed in the NBR matrix. The effects of a coupling agent such as 3‐(mercaptopropyl)trimethoxy silane in C18‐MMT/NBR nanocomposites were studied. The C18‐MMT/NBR nanocomposites in the presence of the coupling agent were identified and characterized by X‐ray diffraction, transmission electron microscopy, a universal testing machine, thermogravimetric analysis, and IR spectroscopy. It was observed that an additional silane coupling agent, 3‐(mercaptopropyl)trimethoxy silane, enhanced the chemical interaction and was accompanied by the formation of Si? O? Si coupling bonds between C18‐MMT and the coupling agent and Si? C coupling bonds between NBR and the coupling agent. This work resulted in improved properties of organo‐MMT/NBR nanocomposites because of the nanoscale effects and strong interaction of the coupling bonds between NBR and organo‐MMT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2633–2640, 2003     

蒙脱土有机插层改性及其插层性能

以十六烷基溴化铵（CTAB）和十八烷基胺（ODA）为有机改性剂制备了有机蒙脱土,研究了反应时间、反应温度、改性剂的用量对蒙托土插层性能的影响,通过傅里叶变换红外光谱图仪（FTIR）、X-射线衍射仪（XRD）和综合热分析（TG-DTA）对其结构和形貌进行表征。结果表明,以十六烷基三甲基溴化铵为改性剂,反应温度为80℃,反...     

废弃椰壳粉/PVC复合材料结构和性能的研究

研究了偶联剂改性椰壳粉的种类及用量、椰壳粉的质量分数对椰壳粉/PVC复合材料性能的影响,并用扫描电镜(SEM)观察了其两相结构和断面形貌.结果表明:硅烷偶联剂KH-550在用量为2%时效果较好,拉伸强度提高了12.6%,冲击强度提高了31%;经过硅烷偶联剂KH-550改性后椰壳粉填充质量分数增大,且降低趋势较小,有效降低复合材料的成本;经过KH-550改性能较大幅度的增大复合材料的耐热变形性能;KH-550改性改善了椰壳粉纤维在PVC基体中分散性和相容性.     

Effect of melt processing conditions on mechanical properties of polyvinylchloride/organoclay nanocomposites

Abstract

Polyvinylchloride compositions have been prepared by the melt intercalation method using a single screw extruder. Different types of nanofiller based on natural sodium montmorillonite were tested. In particular, intercalating agents containing amine groups combined with co-intercalating agent (low or high molecular weight plasticiser) were examined to determine which is the most suitable not only for producing the largest basal spacing and subsequently the best exfoliation of clay tactoids in polymer matrix, but also for the highest beneficial influence on mechanical properties. In the case of improved exfoliation, the effect of compounding was investigated. Therefore, three values of screw speed were studied and some blends were compounded twice to study the retention time in a single screw extruder and the influence on orientation, dispersion and exfoliation of clay particles in the PVC matrix. Moreover, the effect of different types of plasticiser on mechanical properties was also studied. Bis(2-ethylhexyl) phthalate, Bis(2-ethylhexyl) adipate and Lankroflex epoxy plasticiser were tested. Dynamical thermo-mechanical properties were examined and the tensile properties of thin PVC sheets prepared by calendaring. Using X-ray diffraction and transmission electron microscopy, it was found that partially intercalated and disordered structures arose in polyvinylchloride composites containing sodium montmorillonite, while a fine dispersion of partial exfoliation of individual montmorillonite layers in polyvinylchloride matrix was observed when this clay was organically modified. Finally, the value of the tensile modulus for PVC nanocomposites containing as little as 5 wt-% montmorillonite was increased three times provided that the optimum melt processing conditions were used.     

偶联剂对 PPS/PA66/T-ZnOw 复合材料力学性能的影响

采用硅烷偶联剂KH-560和钛酸酯偶联剂TM-38S对四针状氧化锌晶须(T-ZnOw)进行表面改性,制备了相应的聚苯硫醚(PPS)尼/龙(PA)66/T-ZnOw复合材料,研究了两种偶联剂及其复合体系对T-ZnOw表面改性效果和相应复合材料力学性能的影响,并利用扫描电子显微镜对复合材料的断面形态进行了观察。结果表明,钛酸酯偶联剂TM-38S对T-ZnOw的表面改性效果要优于硅烷偶联剂KH-560;两种偶联剂均提高了复合材料的拉伸强度、断裂伸长率和缺口冲击强度,但对复合材料的弯曲强度影响不大。其中TM-38S改性T-ZnOw与PPS/PA66复合后所得材料的力学性能优于KH-560改性T-ZnOw的材料。两种偶联剂的复合体系虽然可以弥补KH-560副反应对T-ZnOw表面改性的不利影响,但对改善复合材料力学性能的协同作用不明显。