蒙脱土/硅烷改性木粉/PVC复合材料

用硅烷YH-62 对木粉(WF) 和插层蒙脱土(OMMT) 进行表面改性, 熔融共混挤出制备了OMMT/ 硅烷改性木粉(STWF) / 聚氯乙烯( PVC) 复合材料。分析了硅烷改性和添加蒙脱土含量对材料力学性能的影响。用X射线衍射(XRD) 、透射电镜( TEM) 和扫描电镜(SEM) 观察了蒙脱土的插层和分散效果, 用傅立叶红外光谱( FTIR) 、X 射线光电子能谱(XPS) 研究了硅烷改性效果, 分析了表面接枝反应机理。结果表明, 硅烷偶联剂与木粉形成了有效的化学键, 并能够与OMMT 表面产生化学连接, 改善木粉与PVC 及蒙脱土间的界面相容性, 提高了木塑材料的力学性能。在适量加入OMMT 后, 木塑材料的力学性能得到了进一步改善。但含量过高, 会形成厚界面层, 甚至使OMMT 和木粉团聚, 分布不均匀, 引起性能降低。      

硅烷修饰对环氧树脂/纳米介孔MCM-41复合材料性能的影响

用偶联剂将纳米介孔MCM-41粉体修饰后与环氧树脂溶液共混,制备出环氧树脂/MCM-41纳米复合材料.研究了偶联剂的含量和不同溶剂的修饰对纳米介孔MCM-41粉体分散性和复合材料力学性能的影响.结果表明,加入适量的偶联剂和在极性较小的介质中修饰,可制备出单分散的纳米介孔MCM-41颗粒增强的新型网络复合材料.偶联剂中的有机基团-(CH2)3-NH2不仅进入孔道、修饰了MCM-41的孔壁,而且使介孔分子筛保持了有序的孔道结构.环氧树脂高分子链与偶联修饰后的MCM-41颗粒的内、外表面以强烈的化学键结合,使MCM-41颗粒均匀分散在聚合物基体中,提高了材料的力学性能,其拉伸强度比基体树脂提高了69%,杨氏模量提高了90%.     

亲水性聚氨酯复合材料的制备与表征

选用湿态纳米羟基磷灰石（HA）与脂肪族聚氨酯（PU）为原料,采用溶液共混法和溶剂挥发法制备了亲水性羟基磷灰石/聚氨酯（HA/PU）纳米复合材料,并采用SEM、吸水实验和力学实验等方法对该复合材料的形貌和性能进行了研究。结果表明磷灰石晶体以纳米状态均匀地分布在PU基质中,过高含量的纳米HA易使纳米粒子团聚,不利于其在PU基体中的均匀分散;在制备PU的多元醇原料中引入亲水性较强的聚乙二醇,可提高PU表面和整体的亲水性;随着硬段含量的增加,复合材料的拉伸强度和弹性模量呈上升趋势,断裂伸长率下降;随着软段中聚乙二醇含量的升高,弹性模量大幅下降,拉伸强度和断裂伸长率先升高后下降;纳米HA的添加可同时提高复合材料的拉伸强度和断裂伸长率,当纳米HA的质量分数为30%时,复合材料的综合力学性能达到最佳。     

稀土改性磨碎玻璃纤维对磨碎玻璃纤维/聚四氟乙烯复合材料性能的影响

采用三种表面改性剂,即硅烷偶联剂（PTMS）、含PTMS的稀土改性剂（PTMS-RES）和稀土改性剂（RES）,对磨碎玻璃纤维表面处理,探讨了不同表面处理剂对磨碎玻璃纤维/聚四氟乙烯（MGF/PTFE）复合材料介电性能、热膨胀系数和热导率的影响。测试了RES、未改性的磨碎玻璃纤维和PTMS-RES改性的MGF的FTIR谱图,并采用SEM对MGF/PTFE复合材料的断口形貌进行分析。结果表明：与未经表面改性的MGF/PTFE复合材料相比,经表面改性的MGF/PTFE复合材料的介电性能、热膨胀系数、热导率都得到改善。由于RES特殊的电子层结构以及对阴离子有强吸引作用,RES改性效果比PTMS更好。由于RES与PTMS共同的作用,PTMS-RES比RES能更好地改善MGF与PTFE的界面,促进MGF与PTFE的界面粘结。     

n-HA/PA系列生物复合材料的结晶行为研究

利用多种手段分析新工艺制备的n-HA/PA系列医用复合材料的结晶行为,结果表明,n-HA纳米粒子在n-HA/PA复合材料的结晶过程中起着重要作用,n-HA的加入在形成新键引起PA高聚物基发生晶型转化的同时导致其结晶度的降低.     

复配稀土改性剂对MGF/PTFE复合材料性能的影响

采用稀土改性剂(RES)与硅烷偶联剂(PTMS)按不同组分配比对磨碎玻璃纤维(MGF)表面进行改性处理,将改性后的磨碎玻璃纤维粉末与聚四氟乙烯分散液机械混合,然后热压制得复合材料。探讨了复配稀土改性剂对MGF/PTFE复合材料介电性能、热膨胀系数(CTE)、热导率的影响。采用FTIR手段对稀土改性剂未改性的磨碎玻璃纤维和改性后的磨碎玻璃纤维的结构进行了测试,并用扫描电子显微镜(SEM)对复合材料的断口形貌进行分析。结果表明,复配改性剂能很好地促进MGF与PTFE之间的界面粘结,提高MGF/PTFE复合材料的性能。当RES、PTMS的含量分别为0.3%(质量分数)、1.7%(质量分数)时,MGF/PTFE复合材料的性能最好。     

APS对PPy/ SiO2纳米导电复合材料的界面改性研究

首先用不同百分含量的氨丙基三乙氧基硅烷(APS)处理SiO2，然后以水为反应介质．通过化学氧化聚合法合成PPy／APS-SiO2纳米复合材料．并利用热失重和四探针对复合材料进行表征和测试。结果表明用APS处理过的SiO2合成的复合材料的电导率和稳定性都有很大提高．其中用1％APS-SiO2合成的复合材料电导率最高，为38．46S／cm。     

n-HA/PA系列生物医用复合材料的制备与表征

设计了一种新工艺方法制备n-HA／PA系列生物医用复合材料．利用各种检测手段分析复合材料的物相结构和性能．提出了复合材料两相间的化学键合方式和聚酰胺基体所发生的晶型转化。     

硅烷化多壁碳纳米管/硅橡胶复合材料的制备和介电性能

采用三种不同官能度的硅烷偶联剂(甲基三乙氧基硅烷(MTES）、二甲基二乙氧基硅烷(DMDES)及三甲基乙氧基硅烷(TMES))在有水条件下对多壁碳纳米管(MWCNTs)进行表面改性,通过FTIR、XPS、TG及SEM表征了MWCNTs改性前和改性后的化学结构。采用机械共混法制备了MWCNTs/硅橡胶(SR)复合材料。SEM结果表明,将不同质量分数的MWCNTs、MWCNTs-MTES、MWCNTs-DMDES和MWCNTs-TMES填充到SR中,硅烷改性可以降低MWCNTs间的相互作用,改善其在SR中的分散性。拉伸试验结果表明,改性MWCNTs与SR之间的相互作用增强,二者的相容性得到改善。当改性MWCNTs含量≤2wt%时,MWCNTs/SR复合材料的弹性模量无明显变化。介电性能测试结果表明,当MWCNTs-MTES质量分数为2wt% 时,MWCNTs-MTES/SR复合材料在104 Hz时介电常数达到5.02,较纯硅橡胶提高了57%,而介电损耗仍低于0.01,保持在极低水平。      

偶联剂改性废纸/PETG生物复合材料

目的制备可生物降解的偶联剂改性废纸/PETG木塑复合材料,并检测其各方面的性能。方法分别采用偶联剂KH550,KH560和KH570对废纸粉进行改性处理,并与PETG制备木塑生物复合材料,通过傅里叶变换红外光谱、力学性能检测、吸水性能分析、扫描电镜和热重分析,研究偶联剂的加入对材料结构、力学性能、吸水性、微观形貌和热稳定性的影响。结果 KH550对复合材料性能的增强效果最好,当KH550质量分数为1%时,复合材料的拉伸强度和弯曲强度达到峰值,分别提高了32.8%和13.7%。结论偶联剂能明显改善复合材料的力学性能和热稳定性,降低其吸水率,在包装领域具有很好的应用前景。     

Highly filled particulate composites enhancement of performances by using compound coupling agents

The compressive and bending strength of epoxy and unsaturated polyester resins composites containing high volume of particulate silicas have been studied. Different coupling agents were tested, whose formulation was tailored to allow the creation of chemical bonding between filler and matrix. Fracture surfaces were analysed by scanning electron microscopy, and a qualitative correlation was found between increasing strength and interfacial adhesion.     

Grafting of cellulose by fluorine-bearing silane coupling agents

The surface of model cellulose fibres, Avicell (AV), as well as that of Whatman paper (WP) was chemically modified with two fluorine-bearing alkoxysilane coupling agents, namely: 3,3,3-trifluoropropyl trimethoxysilane (TFPS) and 1H,1H,2H,2H,perfluorooctyl trimethoxysilane (PFOS). The occurrence of the grafting of soxhlet extracted modified cellulose was confirmed by the presence of silicon and fluorine atoms detected by elemental analysis, X-ray photoelectron spectroscopy and Electron Dispersion Energy/Scanning Electron Microscopy (EDS/SEM). The contact angle measurements showed that, after grafting, the surface of AV and WP samples became totally highly hydrophobic with a contact angle of 140°. Thus, the polar contribution to the surface energy of the modified substrates was found to be close to zero. These modified substrate could be interesting for application such as self-cleaning surface, wipes paper, grease barrier paper or for biocomposite with a polar matrix.     

硅烷类偶联剂对蓄光性荧光粉的表面处理

采用硅烷类偶联剂对蓄光性荧光粉YLAG进行了表面处理,并将荧光粉与尼龙66(PA66)进行熔融共混,利用散射式浊度仪、透射电镜、红外光谱、扫描电镜分别研究了表面处理前后荧光粉的沉降性、微观形貌及化学结构的变化,以及荧光粉/聚合物共混体系的形态结构.结果表明,经硅烷偶联剂进行表面处理后,荧光粉与偶联剂有一定键合作用,表面处理后荧光粉的沉降速度明显减小,在PA66中的分散性得以改善.     

硅烷偶联剂改性聚氨酯的研究

从原料和工艺两方面出发,对以γ-氨丙基三乙氧基硅烷(KH550)为基础的硅烷改性聚氨酯(SPU)进行了改善.原料方面,改性后的KH550由伯氨基转化为仲氨基,反应活性降低;工艺方面,将KH550加料顺序提前.试验结果表明:这两种方法均有利于降低SPU树脂的黏度和提高反应平稳性;较好解决了由于黏度上升太快引起的KH550自聚凝团问题.     

两步法合成酰亚胺环改性硅烷偶联剂

以苯酐、联苯二酐、降冰片烯单酐、烯丙基胺和三乙氧基硅烷为反应物,通过酰亚胺化反应和硅氢加成反应的两步法合成了3种含酰亚胺环的新型硅烷偶联剂,并对其结构和性能进行了研究.红外光谱(FT-IR)、核磁共振(1HNMR)和元素分析表明,酰亚胺环被成功引入到了硅烷偶联剂中.热失重(TGA)结果表明,3种改性硅烷具有良好的热稳定...     

硅烷偶联剂修饰下SiO2-甲基乙烯基硅橡胶分子界面的粘结性

纳米SiO₂掺杂已经成为提升甲基乙烯基硅橡胶(MVSR)性能的有效方法,但是纳米SiO₂容易发生团聚现象,将其直接掺到MVSR基体中时,纳米SiO₂难以在MVSR基体中分散,从而造成SiO₂-MVSR分子界面粘结效果不佳、分子界面存在缺陷等不利影响,进而无法实现提升MVSR性能的目的。为了提升SiO₂-MVSR分子界面的粘结性,使纳米SiO₂在MVSR基体中更易分散,本文构建了未修饰和KH550、KH560、KH570、KH792四种硅烷偶联剂修饰下的SiO₂-MVSR分子界面模型,并对模型进行结构优化和分子动力学计算。通过比较不同模型中分子界面的结合能、粘结深度和粘结热稳定性的变化规律,从分子结构角度分析硅烷偶联剂修饰下SiO₂-MVSR分子界面粘结性提升的原因。研究表明:提升SiO₂-MVSR分子界面粘结性的关键在于优选硅烷偶联剂的非水解基团,当非水解基团中与MVSR分子链相同的化学键占比越大,包含电负性较强原子的数量越多时,修饰后SiO₂-MVSR分子界面粘结性的提升效果就越好,同时,硅烷偶联剂较长的链长与较大的相对分子质量也会对粘结性的提升起到一定帮助。      

Studies on polypropylene composites filled with talc particles

Tensile and impact properties of talc-filled isotactic polypropylene composites are investigated at 0–60 wt% filler contents. Tensile modulus registered an increase whereas tensile yield strength and strain-at-break decreased with increasing filler content. Mechanical restraint imposed by the talc particles on the molecular mobility or deformability of polypropylene explained the increase in modulus and decrease in strain-at-break while decrease in tensile yield strength was attributed to decreased crystallinity and formation of stress concentration points around the filler particles. Izod impact strength decreased with increased talc content. Surface modification of talc with a titanate coupling agent LICA 38 enhanced the filler-polymer interaction, further modifying the composite properties consequent upon significant decrease in the stress concentration. Scanning electron microscopic studies revealed better dispersion of surface-modified filler particles in the polymer matrix.     

Interfacial crystalline behavior in glass-fiber/polypropylene composites modified by block copolymer coupling agents

A kind of di-block copolymer polystyrene-block-poly(γ-methacryloxy-propyltrimethoxysilane) (PS-b-PMPS) with different PS block length and a kind of tri-block copolymer polystyrene-block-poly(n-butylacrylate)-block-poly(γ-methacryloxypropyltrimethoxysilane) (PS-b-PnBA-b-PMPS) with different PnBA block length were synthesized by atom transfer radical polymerization (ATRP), in which PS was a ‘hard’ block and PnBA was a ‘soft’ block. The interfacial crystallization behaviors of glass fiber/polypropylene systems modified with different coupling agents MPS, PS-b-PMPS, and PS-b-PnBA-b-PMPS were investigated on different crystallization conditions. Transcrystallinity could not be induced on non-isothermal crystallization or without maleic anhydride (10%) in polypropylene, but it appeared when glass fibers were treated with common silane coupling agent γ-methacryloxypropyltrimethoxysilane (MPS) and di-block copolymer coupling agent PS-b-PMPS in 135 °C isothermal crystallization without shear and 150 °C isothermal crystallization with shear. However, it disappeared at the interface when the samples were treated with tri-block copolymer coupling agent (PS-b-PnBA-b-PMPS) either under static or shear-induced condition. It might be that the flexible interlayer formed by the flexible block PnBA of PS-b-PnBA-b-PMPS could relax not only the thermal stress resulted from interface temperature gradient arising from sample cooling for crystallization, but also the shear stress induced by fiber/matrix interface shear.     

The effect of silane coupling agents on radiata pine fibre for use in thermoplastic matrix composites

Gamma-aminopropyltriethoxysilane (GS) and dichlorodiethylsilane (DCS) were employed for surface modification of radiata pine (Pinus radiata) wood fibre. Levels of fibre moisture were carefully controlled to optimise chemical and hydrogen bonding with these silane coupling agents. The effect of pre-treatment using 2% sodium hydroxide, shown to be effective in assisting silane coupling for other natural fibres [Composites, Part B: Engng 30 (1999) 321], was also investigated. X-ray photoelectron spectroscopy and nuclear magnetic resonance (NMR) were used to characterise modification of the wood fibre. Concentrations of up to 3.2 wt% Si were obtained on the fibre surface due to silane coupling, however, pre-treatment was found to dramatically reduce this value. NMR provided evidence that coupling had occurred between the fibre and DCS by reaction producing ether linkages between the hydroxyl groups on the wood fibre and silane. Pre-treatment and treatment were found to have an insignificant effect on fibre strength. Composite sheets were produced by blending fibre (5, 10 and 20 wt%) with polyethylene followed by extrusion. An increase in strength was obtained at fibre contents of 5 wt% for all treatments compared to composites with untreated fibre. This is believed to be mainly due to increased compatibility of the fibre surface to polyethylene. However, there was no such improvement obtained at higher fibre contents. Evidence suggests that the production of voids is limiting composite strength.