Effect of chemical modification of poly(butylene terephthalate) on flexible properties
Polimery 2003, No 11-12, 784
Poly(butylene terephthalate) (PBT) modification consisted in preparing the copolymers in which dimethyl isophthalate (DMI) and/or oligo(oxytetramethylerie)diol (PTMOG) of molecular weight 1000 g/mol (Table 1) were used as modifying comonomers. DM1, disturbing the chain structure regularity, decreased the crystallinity degree of PBT, while PTMOG increased the chain flexibility. Mechanical properties (static and dynamic ones) as well as thermal properties of modified PBT were tested (Table 2). The effect of polycondensation duration on limiting viscosity number (Fig. 1) and the effect of modified PBT composition on its melting point (Fig. 2) and yield point (Fig. 3) were presented. Glass transition temperature, melting point and entalphy of melting (Fig. 4) were determined using DSC method. The effect of a temperature on dynamic properties of modified PBT (Figs. 5 and 6) was described. It was found that using of cheap and easily ayailable comonomers let improye PBT flexibility (including impact strength). Their optimal parts in the products of modifications have been found (either 6 wt. % of DMI or a system: 6 wt. % of DMI +6 wt. % of PTMOG or 20 wt. % of PTMOG).
Keywords: poly(butylene terephthalate), chemical modification, dimethyl isophthalate, oligo(oxytetramethylene)diol, flexibility