Polymorphism of isotactic poly(butene-1)

Abstract

The amorphous polymer surfaces of polystyrene (PS, Mn 1⁄4 200 kg/mol, Mw/Mn 1⁄4 1.05) and poly(methyl methacrylate) (PMMA, Mn 1⁄4 51.9 kg/mol, Mw/Mn 1.07) were brought into contact at 21°C to form PS-PS (for 54 days) and PMMA-PMMA auto-adhesive joints (for 11 days). After contact at that temperature corresponding to Tg-bulk 281°C for PS and to Tg-bulk – 88°C for PMMA, where Tg-bulk is the calorimetric glass transition temperature of the bulk sample, the bonded interfaces were fractured and their surfaces were analyzed by atomic force microscopy (AFM). The surface roughness, Rq, of the fractured interfaces was larger by a factor of 3 – 4 than was that of the free PS and PMMA surfaces aged for the same period of time. A similar increase in Rq was found by comparison of the free PS surface aged at Tg-bulk þ 15°C for 1 h and of the surface of the PS-PS interface fractured after healing at Tg-bulk þ 15°C for 1 h. These observations, indicative of the deformation of the fractured interfaces, suggest the occurrence of some mass transfer across the interface even below Tg-bulk 280°C.