Dilute solution and thermal behaviour of random poly(butylene isophthalate/terephthalate) copolymers

✍ Scribed by M Bandiera; A Munari; P Manaresi; M Pizzoli

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 450 KB
• Volume: 30
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(94)90052-3

✦ Synopsis

Random poly(butylene isophthalate/terephthalate) (PBI/PBT) copolymers of various compositions and different molecular weights were synthesized and characterized by vapour pressure osmometry and viscosity measurements in CHCI 3. The Stockmayer-Fixman procedure was applied to viscometric data in order to obtain information on the composition dependence of the unperturbed dimensions. The extrapolated K o values were found to decrease with increasing content of isophthalate units. Thermal characterization in the solid state was carried out by means of a differential scanning calorimeter on PBI/PBT copolymers as well as on PBI and PBT homopolymers. Minima for melting temperature and heat of fusion were observed for the copolymer with 60/40 PBI/PBT molar composition. Amorphous samples in the 40-100% PBI concentration range were obtained by quenching from the melt, characterized by a monotonic decrease of the glass transition temperature 7"8 and by a constant value of the specific heat increment ACp. The Fox equation was found to describe quite well the TB-composition data and permitted calculation of the T s of wholly amorphous PBT.