A number of urethane acrylate nano- and micro-composites have been developed using both ion exchange and silane grafting chemistry. The organically modified clays which were used contained either methacrylate or acrylate functionalities which were capable of reacting with the acrylate groups in the urethane acrylate matrix. [2-(Acryloyloxy)ethyl]trimethyl-ammonium ion (AOETMA) or [2-(methacryloyloxy)ethyl]trimethylammonium ion (MAOTMA) were exchanged onto montmorillonite (MMT) as shown by an increase in the inter-gallery spacing of the MMT. Silane grafting was undertaken using [3-(acryloxy)propyl]dimethylmethoxysilane (APDMMS) or [3-(methacryloxy)propyl]dimethylmethoxysilane (MAPDMMS) and also showed an increase in inter-gallery spacing. The structures of the resulting urethane acrylate composites were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM) and showed predominantly intercalated structures with some exfoliation (more evident in the silane-grafted systems). Dynamical mechanical thermal analysis (DMTA) showed a more significant increase in effective crosslink density (as measured from the plateau of the rubbery modulus) in the composites containing the reactive clays as compared to the unmodified clay, supporting the concept that the acrylate and methacrylate functionalities of the modified clays had reacted with the matrix. Other thermal and mechanical properties were also evaluated. 相似文献
Summary: A new technique, ultrasonically initiated in situ emulsion polymerization, was employed to prepare intercalated polystyrene/Na+‐MMT nanocomposites. FTIR, XRD, and TEM results confirm that the hydrophobic PS can easily intercalate into the galleries of hydrophilic montmorillonite via ultrasonically initiated in situ emulsion polymerization, taking advantages of the multi‐effects of ultrasonic irradiation, such as dispersion, pulverization, activation, and initiation. Properly reducing SDS concentration is beneficial to widen the d‐spacing between clay layers. However, the Na+‐MMT amount has little effect on the d‐spacing of nanocomposites. The glass transition temperature of nanocomposites increased as the percentage of clay increased, although the average molecular weight of PS decreased, and the decomposition temperature of the 1obtained nanocomposites moves to higher temperature.
TEM of PS/Na+‐MMT nanocomposite prepared by ultrasonically initiated in situ emulsion polymerization. 相似文献
Degradation of 4-chloro-2-methylphenol (PCOC), a refractory toxic chemical emitted to the environment from the industrial production of phenoxy herbicides was studied in aqueous solution. Electro-Fenton and photoelectro-Fenton processes were used as the degradation methods. H2O2, produced by the reduction of oxygen at carbon cathode reacted with dissolved metal ions to form hydroxyl radicals, which in turn reacted with PCOC sequentially to degrade the aromatic ring. The effects of using different [Fe2+]/[PCOC]0 and the effect of replacing Fe2+ by Mn2+ ion have been examined. It was found that degradation rate was increased with increasing [Fe2+]/[PCOC]0 ratio from 2 to 4. However, the total charge utilized during the treatment was also increased. The efficiency of PCOC degradation was observed to be higher when Mn2+ was used as the catalyst. The mineralization of aqueous solutions of PCOC, withdrawn from the reactor at certain time interval, has been followed by total organic carbon (TOC) decay and dechlorination. A fast and complete degradation of the aromatic ring was achieved in photoelectro-Fenton system. 41.7% TOC decay and complete dechlorination were observed by consuming only 141.4 C electrical charge during a 300 min photoelectron-Fenton treatment. In the case of electro-Fenton system, 280.7 C electrical charge was consumed during 450 min of electrolysis to attain a similar degradation of PCOC. 14.9% TOC removal and 89.3% dechlorination have been obtained in this system under the applied conditions. 相似文献