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Inverse gas chromatography (IGC) has been used to investigate the surface properties of calcined kaolins and the effect on the mechanical properties of a Nylon-6 composite containing the clay. Modification of the kaolin with an aminosilane coupling agent lowered its surface energy so that it was comparable with that of the polymer matrix and changed the surface from being acidic to being predominantly...
Inverse gas chromatography (IGC) has been used to investigate the surface properties of two calcined kaolins and of polyethylene composites containing calcined kaolin. The results reveal differences in the two kaolins that were not found in XPS spectra nor in their influence on the melting behaviour of the polymer. The kaolin that had a markedly higher surface energy and stronger Lewis acid behaviour...
Inverse gas chromatographic (IGC) measurements are reported for 17 hydrocarbon probes on a low molar mass hexyloxycyanobiphenyl liquid crystal (LC) mixed with linear poly(dimethyl siloxane) (PDMS). The retention properties are compared with a side-chain liquid crystalline bearing the same mesogen. The results show that the retention of the LC polymer is significantly different from a mixture with...
The use of high-intensity ultrasound for forming copolymers by sonication of mixtures of homopolymers is discussed. It is shown that the block copolymers formed in situ by this method can be used to compatibilize blends of immiscible polymers. The mixtures used in this preliminary study were polystyrene with either poly(cis-butadiene) or poly(methyl phenyl silane). The sonochemical method was found...
The decomposition kinetics of potassium persulfate in aqueous solution have been investigated using a radical trapping method. The use of ultrasound was found to markedly accelerate the decomposition so that the sonochemical process at 25 o C occurs at the same rate as the purely thermal reaction at 55 o C. The effect of ultrasound intensity has also been studied and can be used...
The effect of ultrasound on the ring opening polymerization of octamethylcyclotetrasiloxane to give poly(dimethyl siloxane), PDMS, is described. Sonication was found to increase the rate of polymerization over conventional stirring and to give higher molecular weights with lower polydispersities. The results are explained in terms of the efficient mixing and dispersal of acid catalyst given by sonication...
The ultrasonically enhanced oxidation of polyethylene surfaces by potassium and ammonium persulfates is described. The use of ultrasound allows significant levels of surface modification to be achieved using these oxidizing agents under mild conditions. Changes in the water contact angle and attenuated total reflection infra-red spectra were used to follow the changes in surface chemistry. Variation...
Powders of polyethylene, polypropylene, poly(vinyl chloride) and poly(methyl methacrylate) have been subjected to irradiation with high-intensity ultrasound while suspended in water. Changes in the particle sizes and the surface morphology were noted and the pattern of the results was correlated with the physical properties of the materials. In anticipation of sonochemically enhanced reactions at...
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