Studying structure-property relationships in oligomeric engineering thermoplastics by controlled preparation of low molecular weight polymers

摘要

The preparation of a series of oligomeric engineering thermoplastics (PS, PES, PEI and PAI) is reported. ~1H and ~(13)C NMR and FT-IR/ATR spectroscopic techniques are combined to determine the chemical structure of the synthetic polymers, which are produced in good yield and purity. GPC measurements show the weight average molecular weight (M_w) of the synthesised thermoplastics fall in the range 5454-33,866 gmor~(-1) and display polydispersity indices in the range 1.33-1.82. Glass transition temperatures (T_g) values measured by DSC, occur between 107 and 257 ℃ and fall in the pattern PS ＜ PES ＜ PEI ＜ PAI. Molecular simulation is used to probe the structure property relationships displayed by PS and PES and reproduces the elastic properties of PS well within the range of the literature; while the values of PES are less well reproduced. The simulated T_g values of both oligomers agree well with those obtained empirically using DSC.