| The effects of ultrasound on polymer solution have been widely studied.When polymer solutions are subjected to prolonged exposure of high-intensityultrasound waves, stresses induced by cavitation cause homolytic cleavage ofpolymer chains, and consequently cause the molecular weight to decrease. Thebreakage of the C-C bond by ultrasound usually leads to the formation oflong-chain radicals in polymer solutions, which can result in the formation ofcopolymers by coupling with long-chain radicals from different polymers. Thefree radicals formed by the irradiation of a polymer solution can also startpolymerization reactions. It is also known that long-chain polymer moleculescan be ruptured by high-intensity ultrasound during melt extrusion. For polymerblends, during ultrasonic irradiation, long-chain radicals from differentpolymers may also combine and form copolymers. It was found that forimmiscible polymers, ultrasonic treatment during mixing can improveinterfacial adhesion and compatibilization between different phases, which isalso attributed to the formation of a copolymer at the interface by the long-chainradicals generated during ultrasonic treatment.Although the effects of high-intensity ultrasound on polymer have beenwidely studied, it was seldom reported that application of ultrasound on thepolymer nanocomposites prepared with melt dispersion technology. Usingultrasonic mixer that we designed, the key problems of HDPE/nano-SiO2 werestudied in detail on the paper, including the design of ultrasonic mixer,dispersion law of nano-SiO2 in polymeric melt base in the presence ofultrasound and the rheological and crystallization behaviors ofHDPE/nano-SiO2 blends. The goal of the paper was to find why of theseproblems and how to solve these problems, in order to promote development ofnano materiel industry in the field of theory and practice, the key works andconclusions were listed as follows:...
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