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Free radical polymerization of captodative substituted methyl 2-methoxyacrylate (MMOA) was carried out in bulk with or without azo initiators at 90–130 °C. At higher temperatures, bimodal molecular weight distribution polymer was obtained by the polymerization of MMOA irrespective of the presence of initiator in contrast to the polymerization at 90 °C where unimodal polymer was produced. In addition, block copolymers were conveniently obtained by heating the comonomers including vinyl acetate and acrylonitrile at 130 °C in the presence of poly(MMOA) without any initiator. These unique reactions were reasonably explained by the cleavage of captodative substituted carbon–carbon single bond at head-to-head structure in polymer chain, which was produced by recombination termination. [ABSTRACT FROM PUBLISHER]

Network homo- and copolymers were prepared by photo- and thermal radical polymerizations of urethane dimethacrylate bearing photo-initiating Irgacure unit (IrDM) at the same molecule, and their thermal, optical, and mechanical properties were investigated. In the photopolymerization, the resulting IrDM homopolymer indicated the highest glass transition temperature and thermal stability among homo- and copolymers of IrDM and MMA studied. In particular, IrDM homopolymer has the excellent environmental stability, and the coloration of IrDM copolymers and poly(MMA) observed by, heating seems to arise from the additional reactions of free initiator fragment and monomer remained unreacted in the system. For optical properties, all their polymers represented high transparency and refractive index (RI), but the mechanical properties much depended on the contents of IrDM unit in the copolymer. In the thermal copolymerization of IrDM and MMA using benzoyl peroxide (BPO) as an initiator, the resulting copolymers have still a photo-initiating unit at the bridge in the network structure, and post photo-irradiation to the polymer changed the mechanical performances. In addition, the copolymers of IrDM with 2-hydroxy methacrylate and acrylic acid (AA) were also prepared and their unique functionalities were investigated. [ABSTRACT FROM PUBLISHER]

A poly(phenylene sulfide) (PPS)-based nanocomposite (PPSNC) filled with titanate layers was used as a matrix polymer in a PPS/maleic anhydride ethylene butadiene co-polymer (MA-EBR) blend. The toughness of the PPS was increased significantly, because the inorganic titanate layers behaved as an effective compatibilizer to enhance the blending effect of MA-EBR. Scanning electron microscopy analysis confirmed that MA-EBR domains were finer and uniformly dispersed with a small particle size in the PPS matrix. In addition, transmission electron microscopy analysis proved that titanate layers aggregated at the interface between the PPS and MA-EBR. On the other hand, the initial morphology of the titanate layer in the PPSNC was maintained when untreated EBR was used as the domain polymer. The morphologies of titanate layers in the three types of polymers blended with this nanocomposite technique, including PPSNC/PA6, were investigated to discuss the factor which titanate layers affect the morphology of domain polymers, and it was indicated that the behavior of titanate layers was governed by an affinity between polymers and titanate layer surface. [ABSTRACT FROM AUTHOR]

Organically-modified layered titanates (OMLTs) were used as new layered fillers to prepare poly(p-phenylenesulfide) (PPS)-based nanocomposites. The melt mixing of PPS with any OMLT led to the delamination of stacked titanate layers, regardless of the miscibility between intercalants of OMLTs and PPS, and attained a nanoscale dispersion of titanate layers which is an exfoliation structure in the PPS matrix. Transmission electron microscopy (TEM) analysis and X-ray diffraction (XRD) measurement confirmed that titanate layers were successfully dispersed in the PPS matrix. OMLTs had a specific delamination mechanism, which is governed by melt mixing temperatures. In the melt processing at high temperature, the delamination of stacked-layers in OMLTs was facilitated by retaining an initial interlayer spacing of the layered structure and decreasing the surface charge density of the titanate crystal. [ABSTRACT FROM AUTHOR]

Interpenetrating polymer networks (IPNs) were prepared by photo and thermal polymerizations of diacrylate, diepoxide and hybrid monomer mixtures, in which the functional groups in each monomer were linked by bisphenol A hard segment. Dynamic mechanical analysis, tensile tests, thermogravimetric analysis, hardness analysis and visible spectrometry were performed to evaluate the properties of the IPNs and their precursors. The IPNs obtained, containing a small amount of diepoxide, indicated the highest mechanical properties at a ratio of hybrid/diacrylate of around 1:2. This composition also agreed with the composition showing highest surface hardness and transparency. In addition, the influence of microwave irradiation on curing time was also studied. [ABSTRACT FROM AUTHOR]