Effects of SBA-15 and its content on MMA solution polymerization and PMMA composites

An ordered mesoporous material, such as SBA-15 was considered as a promising reinforcement agent for polymeric materials due to its large surface area and uniform pore structure. In this paper, poly(methyl methacrylate) (PMMA)/SBA-15 composites were prepared by in situ free-radical solution polymerization of MMA in the presence of SBA-15. The effects of SBA-15 content on solution polymerization and the properties of the final polymer composite were investigated. The PMMA molecular weight and its distribution in PMMA/SBA-15 composites were determined by gel permeation chromatography. Fourier-transform infrared spectra, X-ray diffraction, thermal gravimetric analysis (TGA), differential scanning calorimeter and dynamic mechanical analysis were used to characterize the structure and properties of the composites. The morphology of the composites was observed by scanning electric microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the monomer conversion dropped off, but the polymer average molecular weight increased upon the introduction of SBA-15 into solution polymerization process. When compared with pure PMMA, the storage modulus of the composites was improved and the highest improvement was acquired at 1 wt% of SBA-15, based on the monomer feed content. The glass transition temperatures of the composites were increased slightly. TGA results confirmed that the thermal stability of the composite was not influenced much and a higher degree of terminal vinyl groups was formed in the product of polymerization. SEM and TEM images indicated that SBA-15 particles were incorporated into the polymer matrix.     

Effects of mesoporous SBA-15 contents on the properties of polystyrene composites via in-situ emulsion polymerization

Different loading of mesoporous molecular sieve SBA-15 was used to prepare polystyrene (PS)/SBA-15 composite materials via in-situ emulsion polymerization. The influence of SBA-15 silica on the styrene emulsion polymerization was studied regarding to the monomer conversion, particle size and particle size distribution, stability and viscosity of the resulting emulsion. The structure and properties of the composites were investigated by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and gel permeation chromatography (GPC). In addition, the glass transition temperature (T_g), thermal mechanical property and thermal stability of the composite film were measured by differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. The results indicated that the composite emulsion showed high monomer conversion, thick viscosity, low coagulum, uniform particle size and broad size distribution. Molecular weight of the polymer decreased with the increase of mesoporous silica. SBA-15 silica was dispersed evenly in PS matrix at a loading of 5 %. The PS/SBA-15 composite material containing 10 % silica maintained a certain ordered structure. DMA results demonstrated that PS/SBA-15 composite exhibited greater storage modulus and high T_g compared to pure PS. The improved thermal stability and T_g of the composite were also confirmed by the TGA and DSC.     

SBA-15／PMMA杂化材料力学性能及热性能研究

采用溶胶一凝胶法制备了二维六方介孔结构的SBA-15,利用原位分散聚合法制备（SBA-15／0wt％DBP／PMMA,SBA-15／15wt％DBP／PMMA和SBA—15,25wt％DBP／PMMA）三种三维纳米网络结构的杂化材料。通过FT—IR、XRD、TEM、DSC和SEM等方法对SBA-15／DBP／PMMA杂化材料进行了表征。结果表明：DBP和SBA-15的加入对PMMA分子链的化学结构未造成任何影响,且SBA-15在PMMA基体中仍能保持介观有序结构;SBA-15对脆性PMMA具有较好的增强增刚作用,且DBP的含量越高,杂化材料拉伸强度和模量提高程度相对减小;三种杂化材料的rrg均随SBA-15含量的增加而提高,且DBP的含量越高,杂化材料的Tg提高幅度越小。     

SBA-15/UP原位复合材料摩擦性能的研究

采用KH570对介孔二氧化硅SBA-15进行表面处理,通过原位聚合方法合成SBA-15/不饱和聚酯(UP)复合树脂,后再通过共混、辊炼、模压成型制备了SBA-15/UP复合材料。研究了加入SBA-15对SBA-15/UP复合材料的摩擦磨损性能、硬度、动态力学性能的影响,通过扫描电子显微镜(SEM)对复合材料的磨损表面形貌进行观察。结果表明,经改性后的SBA-15加入使复合材料的体积磨损率降低了26%,玻璃化温度提高了16℃。     

原位聚合法制备高透光率韧性PMMA复合树脂的研究

采用原位聚合法制备PMMA/P(BA-St)/PMMA三层韧性有机玻璃复合树脂,分子设计方法的使用,保持了材料的透明性。考察了韧性粒子粒径、橡胶相组成以及橡胶含量对材料力学和光学性能的影响。借助透射电镜、扫描电镜和动态光散射方法对复合胶乳粒子以及所制材料的形态结构进行了表征。结果表明:橡胶相的折光指数对材料的透光率有明显影响,橡胶相玻璃化温度越低,越有利于增韧。     

Effect of talc/MMA in situ polymerization on mechanical properties of PVC‐matrix composites

In this study, polymethyl methacrylate (PMMA)‐coated talc was produced by the in situ polymerization of methyl methacrylate on the talc surface. The polymerization reaction was performed by both batch and semicontinuous emulsion processes. The polymerization kinetics, particle size and distribution, grafting efficiency, and coated‐talc morphology were systematically investigated. It was found that the talc particles have no effect on the polymerization of PMMA. The PMMA produced was found to cover the talc surface well. However, only a small amount can be grafted onto the talc. The size distribution of talc particles treated by semicontinuous emulsion polymerization is more uniform than by batch polymerization. The treated talc was subsequently used as filler in a poly(vinyl chloride) (PVC) matrix, and mechanical properties of the PMMA‐coated‐talc/PVC composites were studied. Morphological structure of PVC‐matrix composites revealed that the PMMA coating on talc improved the dispersion of talc in the PVC matrix and enhanced the interfacial adhesion between the talc and PVC. The mechanical properties of the composites, especially the impact strength, were found to be improved. There appears to be a critical covering thickness of PMMA on the talc surface for optimum toughening. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2105–2112, 2001     

纳米CaCO_3的接枝改性及其填充PVC复合材料的性能

采用表面原位接枝聚合在纳米CaCO3颗粒表面引入聚甲基丙烯酸甲酯(PMMA)或聚丙烯酸丁酯(PBA),用共混法制备了纳米CaC03/PVC复合材料,研究了不同界面特性时纳米CaCO,/PVC复合材料的力学性能.研究结果表明:通过表面原位接枝聚合反应可以在纳米CaCO3颗粒表面接枝PMMA和PBA;表面接枝聚合改性大大促进了纳米CaCO3粒子在PVC基体中的分散行为,增加了复合材料的拉伸强度以及与聚合物的界面粘接强度,但复合材料的冲击强度有所下降.     

A study on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization

A number of batch polymerizations were performed to study the effect of pristine nanoparticle loading on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization. In order to improve the dispersion of silica nanoparticles in PMMA matrix, the silanol groups of the silica are functionalized with methyl methacrylate groups and modified nanoparticles were used to synthesize PMMA/modified silica nanocomposites via RAFT polymerization. Prepared samples were characterized by thermogravimetric analysis (TGA), dynamic light scattering (DLS), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). According to results, introduction of modified nanoparticles results in better thermal and mechanical properties than those of pristine nanoparticles. Also, surface modification and increasing silica nanoparticles result in variation of thermal degradation behavior of nanocomposites. The best improvement of mechanical and thermophysical properties is achieved for nanocomposites containing 7 wt. % silica nanoparticles.     

PMMA-mesocellular foam silica nanocomposites prepared through batch emulsion polymerization and compression molding

PMMA-mesoporous silica nanocomposites were prepared for the first time through in situ batch emulsion polymerization of methyl methacrylate in the presence of large pore MSU-F silica with a mesocellular foam structure (24.8 nm average cavity size) and subsequent compression molding of the polymer-silica nanoparticle mixtures. For composites containing 5.0 wt % silica, the onset decomposition temperature and the temperature at 10% weight loss for the nanocomposite increased 41 °C and 50 °C, respectively, in comparison to pure PMMA. The glass transition temperature of the nanocomposite increased 9.3 °C, as determined by differential scanning calorimetry. In addition, the storage modulus determined by dynamic mechanical analysis increased 17% and 80% at 50 °C and 100 °C, respectively. Substantial improvements in tensile strength (+50%) and modulus (+72%), were achieve at 10 wt % nanoparticle loading. Composites made by compression molding of physical mixtures of PMMA and MSU-F silica powders provide less improvement in thermal stability, glass transition temperature and mechanical properties in comparison to the composites made through in situ batch emulsion polymerization. Unlike previously reported composites made from nanoclays, the silica composites reported here show improvements in both thermal stability and mechanical reinforcement.     

丁苯橡胶/纳米硅铝管复合材料的制备工艺与性能

分别采用直接共混法、填料预处理法、原位改性分散法、乳液法制备了丁苯橡胶/纳米硅铝管（SBR/SANT）复合材料,并对其结构和性能进行了表征。结果表明：采用原位改性分散的方法能够有效改善填料与橡胶间的界面强度,制备得到力学性能优异的SBR/SANT复合材料。采用乳液法制得复合材料的填料分散较好,扫描电子显微镜观察到SANT基本以单管分散,其导热性能明显优于干法混合。随着纳米硅铝管用量增大,SBR/SANT复合材料的硬度、定伸应力、拉伸强度、撕裂强度和导热系数提高,拉断伸长率下降。     

氧化石墨烯对RDX/PMMA安全性能及力学性能影响

为改善RDX的安全性能和力学性能,采用乳液聚合法制备RDX/聚甲基丙烯酸甲酯/氧化石墨烯(RDX/PMMA/GO)微球,并用相同方法制备了RDX/PMMA复合粒子进行对比;通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)和差示扫描热量仪(DSC)对样品进行表征,并测试其撞击感度和药柱的静态力学性能。结果表明,包覆后RDX/PMMA微球形貌趋于球形,RDX/PMMA/GO粒子存在明显的层状皱褶;RDX晶型均未发生改变;与原料RDX和RDX/PMMA相比,RDX/PMMA/GO微球的表观活化能分别提高22.16kJ/mol和15.17kJ/mol,升温速率趋近于0时的峰温和热爆炸临界温度与原料RDX相比分别提升6.45℃和6.23℃;特性落高由包覆前的26.74cm分别提至62.95cm和78.52cm,撞击感度明显降低。RDX/PMMA/GO抗压强度比RDX/PMMA增加了7.5MPa,表明GO的加入对复合材料的力学性能提升明显。     

PMMA／凹凸棒粘土复合材料的制备及其性能研究

以有机改性凹凸棒粘土为填料,采用原位聚合法制备了聚甲基丙烯酸甲酯（PMMA）／凹凸棒粘土（ATP）复合材料,通过红外光谱（FTIR）、扫描电镜（SEM）、热重（TG）、力学性能测试等方法对复合材料进行分析和表征。结果表明,改性凹凸棒粘土与PMMA的相容性良好,在PMMA中分散均匀。而其独特的一维纤维棒状结构也可以对PMMA在一定程度上起到补强、增韧作用,当凹凸棒粘土的加入量在1．5％时,其综合力学性能较佳。     

纳米二氧化硅增强增韧环氧树脂的研究

通过原位分散聚合法制得了环氧树脂 /纳米二氧化硅 ( nm Si O2 )复合材料。利用拉伸试验、冲击试验、扫描电镜、热重分析等方法研究了该复合材料的结构和性能。结果表明 nm Si O2 均匀地分散在环氧树脂基体中 ,有效地改善了环氧树脂的力学性能 ,并且材料的耐热性也有所提高。     

原位聚合PLA/HA复合材料的性能研究

采用原位聚合法和超声波辅助分散溶液共混法，分别制备了羟基磷灰石质量分数为30％的聚乳酸（PLA）／羟基磷灰石（HA）生物可降解复合材料，对其结构与力学性能进行了研究。结果表明，HA的存在对乳酸的聚合有一定的影响，使其摩尔质量降低、分布变宽。与共混法相比，原位聚合法改善了HA在复合材料中的分散性，在PLA与HA之间形成了较强的结合界面，从而提高了PLA玻璃化温度和力学性能。     

Production of leather-like composites using short leather fibers. II. Mechanical characterization

Leather-like composites were prepared by addition of chemically modified short leather fibers (SLF) into a plasticized polyvinyl chloride (pPVC) matrix. The fibers were subjected to chemical modification by emulsion polymerization to achieve good interfacial adhesion between SLF and the pPVC matrix. The SLF with chemical modification were obtained from three different reaction conditions where these SLF have different percentages of grafted and deposited PMMA polymer onto the fiber surface. The incorporation of the SLF into the thermoplastic matrix was carried out using a torque-rheometer and the composites obtained were molded by compression. Tensile and tear mechanical tests were performed on composite samples, and the morphology of the fractured surfaces was analyzed using scanning electron microscopy (SEM). The results show that the incorporation by grafting of polymethyl metacrylate (PMMA) onto the fibers produced a significant improvement of their interfacial adhesion to pPVC, promoting the compatibilization between the fiber surface and matrix. The findings are discussed and interpreted in terms of enhanced adhesion at phase boundaries. Overall, the results confirm that it is possible to produce modified leather composites based on a pPVC matrix, which exhibit relatively high tensile strength, tear resistance and flexibility. These composites are very suitable candidate materials for applications in the footwear industry.     

Study on the structure and properties of Poly(methylmethacrylate)/Polypyrrole-Graphene Oxide nanocomposites

In this paper Poly(methylmethacrylate)/Polypyrrole-Graphene Oxide (PMMA/PPy-GO) nanocomposites were prepared using in-situ chemical polymerization method and its structure and properties were studied. Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis confirmed that PPy nanopraticles covered the GO nanosheets surface and PMMA/PPy-GO nanocomposite were prepared successfully. The mechanical, electrical and thermal stability of the PMMA nanocomposites were also investigated using Tensile, Impact, Thermogravimetric analysis (TGA) and four-point probe methods. Correlation between direct morphological observation and final properties demonstrated that network structure formed by PPy-GOs in PMMA matrix. Tensile analysis showed that the addition of 0.4 wt % PPy-GO hybrids lead to 24.4 % enhancement in the Young’s modulus of PMMA compared to 5.0 % improvement that achieved at the same loading level of GO. Electrical conductivity measurement showed that dispersion of PPy-GO in PMMA matrix increased AC conductivity in the range of 8 orders of magnitude compared to PMMA. TGA analysis showed that the thermal stability of the PMMA nanocomposites improved over 20 ?C.     

PVC/竹粉复合材料制备

在固相反应器中对竹粉进行机械活化乙酰化改性,将改性竹粉与聚氯乙烯(PVC)混合均匀,热压成型制备PVC/竹粉复合材料.考察催化剂浓硫酸用量、乙酸酐用量、机械活化时间和温度对复合材料力学性能的影响,并对改性前后的竹粉及其复合材料断面进行表征.结果表明,当乙酸酐与改性竹粉的物质的量之比为3.5︰1、机械活化温度为80℃、机...     

水性环氧树脂包覆有机蒙脱土制备木材胶粘剂

摘要：水性环氧树脂通常含有水溶性分子或分子链，导致在高温和潮湿条件下作为木材胶粘剂时耐水性及力学性能较差。采用有机改性的纳米蒙脱土改性水性环氧树脂增强水性环氧树脂胶粘剂的耐水性及力学性能。并通过乳液包覆蒙脱土的方法与直接共混的方法对比，研究了不同添加量有机蒙脱土（0%，3%，6%，9%）对胶粘剂性能的影响。胶粘剂的耐水性及力学性能通过测量胶粘剂在干燥及潮湿条件下的剪切强度来表示。通过TGA、SEM、TEM、DSC研究了复合胶粘剂的热稳定性和结构。结果表明，在水性环氧树脂中添加有机改性的纳米蒙脱土，可以有效地提高胶粘剂的粘结强度，此外，采用乳液包有机覆蒙脱土的方法比直接共混的方法制备得到胶粘剂，有机蒙脱土在胶粘剂中分布更均匀，具有更优异的力学性能，说明有机蒙脱土在复合材料中的分散质量是影响复合胶粘剂性能的主要原因。     

原位聚合制备碳纳米管/PMMA复合材料的研究

采用原位聚合的方法，制备了多壁碳纳米管／聚甲基丙烯酸甲酯复合材料。多壁碳纳米管经过强酸氧化处理。表面具有有机活性。碳纳米管的加入并未使聚合诱导期延长，但令体系粘度增加，自加速现象提早出现。DMA和TGA的研究表明，碳纳米管用量少于1．0％的复合物玻璃化温度降低，分解温度无显著变化。加入1．0％的碳纳米管可以使PMMA复合材料冲击强度提高80％以上。断面扫描电镜表明，碳纳米管呈单管分散于基体中。     

Effect of Micro- and Nano-Particle Fillers at Low Percolation Threshold on the Dielectric and Mechanical Properties of Polyurethane/Copper Composites

Polymeric composites based on polyurethane (PU) as the matrix and copper (Cu) particles as the filler were prepared by using solution casting. The effects of micro- and nano-particles size and content on the dielectric and mechanical properties depend upon the interface between metal filler and polymeric matrix. The dispersion of the fillers within the polymeric matrix was investigated by scanning electron microscopy (SEM). The SEM results showed a relatively homogeneous dispersion for the micro-particle size and the existence of the aggregation and poor compatibility for the nano-particle size. Differential scanning calorimetric measurements showed that the glass transition temperature (Tg) in case of micro-particles is quite similar to that of the neat PU, but the increase in Tg was observed when nano-particles were used. The dielectric properties of the composites as a function of the filler concentration and filler size was investigated in the frequency range of 100?Hz–10?kHz, showing an increase in dielectric constant with increasing filler content. This increase was more significant when using the nano-particles. The mechanical properties of the composites were obtained by using a tensile tester (ASTM D412). The tensile modulus generally increased with increasing Cu content, but the extent of increase was lower in case of micro-particles. The tensile strength of composite filled with nano-particle slowly decreased when filler content increased, while there was a significant in case of micro-particle as fillers. In addition, the elongation at break decreased with increasing Cu content, but the effect was more significant when micro-particle were employed. AFM image was used to investigate a topology of the tensile fractured surface, showing the mechanism of failure of the composites.