Preparation and Properties of Composite Materials Composed of Hyperbranched Aromatic Polyamide and Vinyl Polymers

Abstract

End amino functional groups of the hyperbranched aromatic polyamide were chemically modified with acryloyl chloride or methacryloyl chloride. Self-crosslinking reactions of the acryloyl and methacryloyl functionalized hyperbranched aromatic polyamides were carried out in the DMF solution containing AIBN at 100 'C for 24 h. IR spectra of the crosslinked films suggested the conversion of the vinyl groups in the functionalized polymers. The conversion was improved by the addition of methacrylic acid (MA) as a comonomer to form composite materials. The solubility of the crosslinked and composite materials decreased significantly in comparison with the starting frnctionalized polymers. The ratio of MA and the vinyl groups in the fmnctionalized hyperbranched polymers affected the quality of the composite films. Transparent yellow films were obtained when the ratio was lower than 110. The transparent films showed regular small domains observed by transmission electron microscope, while irregular coagulates of the hyperbranched polyamide were observed for opaque films. Thermogravimetric analysis (TGA) revealed that the decomposition temperatures (Td) for all of the composites were lower than the Td (296° C) of the hyperbranched polymer prepared from the AB2 monomer. Glass transition temperatures (T9) of the composites were lower than that of the original hyperbranched polyamide, when the composite was composed of a large amount of MA. Softening points (Ta) of the composite materials are dependent on the feed ratio of MA and the terminal vinyl groups of the functionalized hyperbranched polymers. In the presence of small amount of MA, T, increased to about 190° C. After the increase, T, decreased gradually to about 155 'C with increasing amount of MA.