碳纳米管径对MWCNTs／PMMA复合物耐磨损性的影响

研究了具有四种不同碳纳米管径的MWCNTs/PMMA复合物系的耐磨损性.对MWC-NTs进行酸化处理,采用原位本体聚合方法制备复合板,用砝码质量法评价复合板的耐磨损性.研究结果表明：混酸处理后,MWCNTs在MMA中的分散稳定性得到明显提高,L-MWNTs-4060在PM-MA中分散得最好,L-MWNTs-60100分散得最差;L-MWNTs-4060型碳纳米管复合板的耐磨损性最好,L-MWNTs-60100型的最差;而L-MWNTs-1030和L-MWNTs-2040型的介于其两者中间.     

纳米SiO2表面高聚物接枝改性的研究

介绍了利用硅烷偶联剂KH-570对纳米SiO2进行表面处理的方法;研究了利用悬浮聚合法在改性纳米SiO2 表面自由基接枝PMMA的途径。并对PMMA的接枝率及接枝效率随引发剂用量的变化关系进行了研究。     

The influence of matrix modification on fracture mechanisms in rubber toughened polymethylmethacrylate

The fracture behavior of composite rubber particle-toughened polymethylmethacrylate has been investigated over a wide range of test speeds, encompassing impact conditions. When the entanglement density of the matrix was increased and its glass transition temperature reduced by copolymerization, there were significant increases in the crack initiation and propagation resistance of the particle-toughened materials at low to intermediate speeds. At impact speeds, on the other hand, where crazing became the dominant matrix microdeformation mechanism in all the materials investigated, the fracture response of the copolymer matrix was closer to that of the polymethylmethacrylate homopolymer, and the toughening effect of the rubber particles was no longer effective in either case. This is discussed in terms of the onset of the matrix β transition, associated with the transition from shear to crazing, and the α transition of the rubber domains, both of which occurred in the temperature range immediately below room temperature in low frequency dynamic torsion measurements.     

热老化对PMMA塑料光纤损耗的影响

主要研究了热老化对PMMA塑料光纤损耗的影响及其影响机理.发现热物理老化减少了PMMA聚合物中的局部取向,使其形成少量的半结晶或结晶区,增加了其散射损耗;而热化学老化导致PMMA聚合物的氧化降解,严重增加了其在短波长的电子转移吸收损耗.     

Measurement approaches to develop a fundamental understanding of scratch and mar resistance

Instrumented indentation and confocal microscopy were used to characterize the surface mechanical response of polymeric materials. Viscoelastic behavior was measured using instrumented indentation. A model based on the contact between a rigid probe and a viscoelastic material was used to calculate values for the creep compliance and stress relaxation modulus for two polymeric materials, epoxy and poly(methyl methacrylate) or PMMA. Scratch testing was performed on these materials with various probes under a variety of conditions, and confocal microscopy was used to characterize the resulting deformation. Relationships among viscoelastic behavior, scratch damage, and appearance are currently being explored using these methods along with finite element modeling. Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 13–14, 2004, in Philadelphia, PA.     

Study on the suppression mechanism of water mist on poly(methyl methacrylate) and poly(vinyl chloride) flames

In this study, the action of water mists on poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC) in a confined space under different external radiant heat fluxes was studied. Water mist was generated by a downward‐directed single pressure nozzle. Physical characteristics of the water mist were measured by laser doppler velocimetry and the adaptive phase doppler velocimetry system. The heat release rate, oxygen, carbon dioxide, and carbon monoxide concentrations, and other important parameters of the interaction under various experimental conditions were measured with cone calorimeter. To explain experimental results, the chemical suppression mechanisms of water mist extinguishing PMMA and PVC flames are investigated from literatures, and the corresponding proposed chemical reactions with water mist are presented. The investigation shows that aromatic compounds are formed by light hydrocarbon products with water mist for PMMA flame. Otherwise, for PVC flame, the decrease of temperature with water mist prevents aromatic compounds from oxidation and degradation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1130–1139, 2006     

连续反应制备聚合物光纤用PMMA芯颗粒料

详细介绍了连续反应法制备聚合物光纤用PMMA芯颗粒料的工艺流程及生产设备总体结构，采用该法可大幅缩短生产时间，可制备出纯度达到95％以上的PMMA颗粒料。     

Polymer–organoclay hybrids by polymerization into montmorillonite‐vinyl monomer interlayers

A different series of polymer–clay hybrid materials have been prepared by modification of the clay with different vinyl monomers, followed by polymerization of different ratios of vinyl monomers–clay with the monomers, such as methyl methacrylate, hydroxyethyl methacrylate, and styrene‐maleic anhydride. The materials were investigated by IR, which confirmed the intercalation of vinyl‐cation within the clay interlayers, and by TGA, which illustrated that phosphonium cation has high thermal stability than ammonium cation. Swelling studies of these materials in different organic solvents showed that the swelling degree increases as clay ratio decrease, and also showed higher swelling relative to vinyl–clay. X‐ray diffraction illustrated that the nanocomposites were exfoliated up to a 25 wt % content of organoclay relative to the amount of polymer. SEM and TEM examined the micrograph, which showed a good dispersion of the polymers into clay galleries, and formation of nanosize particles ranged 150–300 Å. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Graded‐index plastic optical fiber with high mechanical properties enabling easy network installations. II

It was shown how high mechanical strength should be provided in the high numerical aperture (NA) graded‐index plastic optical fiber (GI POF). In this newly developed GI POF, a copolymer of methyl methacrylate (MMA) and 2,2,2‐trifluoroethyl methacrylate (3FMA) was used to increase the NA. The GI POF we proposed previously was composed of a PMMA homopolymer cladding and a doped PMMA core. It was previously shown that substituting the copolymer P(MMA–3FMA) for the PMMA as the cladding material made little change in the fiber's light‐transmission characteristics. This study focused on mechanical flexibility, which is one of the most important advantages of the POF. It was found that the P(MMA–3FMA)‐clad GI POF had almost the same or superior mechanical strength in addition to the excellent light‐propagation characteristics. It was also found that such excellent mechanical properties were achieved using a small dopant concentration and optimum heat‐drawing conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 410–416, 2004     

Strength of Adhesive Joints Immersed in Different Solutions

Polymethyl methacrylate/epoxy/polymethyl methacrylate (PMMA/epoxy/PMMA) and aluminium/ epoxy/aluminium joints were immersed in different reagents including saline water, distilled water, sodium hydroxide solution, and sulphur dioxide solution. The joints were immersed in the reagents with and without a constant tensile load. The joints were also tested in air. Four loading periods were selected. At the end of each loading period, the joints were loaded in a tensile testing machine until failure. The results of the tests showed that the tensile strength of the aluminium joints was reduced, while that of polymethyl methacrylate was increased after immersion. The same results were obtained regardless of whether the submerged joint was loaded or not. Moreover, corrosion was found on the aluminium joints immersed in the sodium chloride solution and sulphur dioxide solution.