Surface mobility and diffusion at interfaces of polystyrene in the vicinity of the glass transition

✍ Scribed by Yuri M. Boiko; Robert E. Prud'homme

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 136 KB
• Volume: 36
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199803)36:4<567::aid-polb3>3.0.co;2-m

✦ Synopsis

Symmetric polydisperse ( M w Å 23 1 10 4 , M w /M n Å 2.84) and monodisperse (M w Å 21 1 10 4 , M w /M n õ 1.05) polystyrene (PS), and asymmetric polydisperse PS/ poly(2,6-dimethyl 1,4-phenylene oxide) (PPO) interfaces have been bonded in the vicinity of the glass transition temperature ( T g ) of PS. In a lap-shear joint geometry, strength develops in all cases with time to the fourth power, which indicates that it is diffusion controlled. Strength developing at short times at the polydisperse PS/PS interface, at 90ЊC, is higher than that at the monodisperse interface, at 92ЊC (at T g 0 13ЊC in both cases), presumably due to the contribution of the low molecular weight species. The decrease of strength at the PS/PPO interface when the bonding temperature decreases from 113 to 70ЊC, i.e., from T g / 10ЊC to T g 0 33ЊC of the bulk PS, indicates a high molecular mobility at the surface as compared to that in the bulk, and can be expressed by a classical diffusion equation, which is valid above T g (of the surface layer).