A study on free-volume properties of styrene-acrylic ester type copolymers

✍ Scribed by Chenze Qi; Shuihe Zhang; Yanjie Wu; Huamei Li; Ge Wang; Gao Huai; Tianmin Wang; Jiantai Ma

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 189 KB
• Volume: 37
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19990901)37:17<2476::aid-polb19>3.0.co;2-4

✦ Synopsis

The positron annihilation lifetime measurements have been performed on a number of amorphous styrene-methyl acrylate copolymers and styrene-butyl methacrylate copolymers. The densities of copolymers were obtained with immersion method by using a capillary pycnometer and the average molecular weights were determined by gel chromatography. The lifetime 3 of ortho-positronium (o-Ps) pick-off annihilation have been found to correlate with side group volume and polarity of macromolecular chains in the copolymers, and relative intensity I 3 is attributed mainly to the electron-attracting groups trapping the spur electrons and positrons. The experimental results have been discussed on the basis of the structural variation of macromolecular chains. In addition, the PALS measurement as a function of time for polystyrene and several styrene-methyl acrylate copolymers has also been performed. The result shows that an electric field is built in polymers during extended positron annihilation spectroscopy measurement, and the field effect is a main factor which causes the decrease in I 3 with time.