Diffusion of butanediol in poly(butylene terephthalate) (PBT) melt and analysis of pbt polymerization reactor with surface renewal

Abstract

A reactor with surface renewal, originally designed for poly(ethylene terephthalate) (PET) polymerization, was applied for poly(butylene terephthalate) (PBT) polymerization. A comprehensive model including side reactions was developed and compared with the experimental results. The diffusivity of butanediol (BD) in PBT melt was measured separately by desorption experiments (Db − 1.08 × 106 exp(−32600 / RT) (m2/min)). Optimum operating temperature for PBT polymerization was found to be around 250°C in order to avoid degradation.

Chain extension of poly(butylene terephthalate) by reactive extrusion

“…It has been produced by transesterifying and then polycondensing a mixture of dimethyl terephthalate and 1,4-butanediol in the presence of catalysts at a high temperature and in a vacuum. [1][2] However, the general grades of PBT with a relatively low molecular weight have inferior mechanical properties and do not meet the requirements of some of the applications. The standard industrial polymerization processes are efficient only in producing PBTs with a MFI higher than 20 g/10 min because the high viscosity makes it very difficult for small molecules, such as water or methanol, to escape.…”

“…The carboxyl content could increase with an increase in the reaction time, leading to less thermal and hydrolytic stability. 1 To overcome the limitation of the above-mentioned reaction, a post-polycondensation method in solid phase has been developed. 3 A highermolecular-weight PBT can be obtained by this method.…”

Molecular structure influence on bending behavior of polyester filaments examined using a modified cantilever bending test

“…Exemplary the fiber-fiber compound tests on cantilever after Fischer et al, 5 the balanced fiber method of Scott and Robins 1,6 or resonance methods, like the method of Guthrie et al can be stated. [23][24][25][26][27][28] The result is a low melt strength, limiting the use for several processes. Other tests, in particular presented in newer publications show more comparable results but have setups requiring long measurement times, high effort for sample preparation and/or expensive devices.…”

“…7 The loop test of Fukuda 8 or Zhou and Gosh 9 or the bending test of Matthewson, 1,10 with simple setups give relative values, which can only be referenced to the respective method and are based on the assumption of pure linear-elastic material behavior. 20,21,26 High molecular grades can be gained by solid-state polycondensation, which needs high reaction times (of several hours) and high costs in large-scale production [28][29][30][31][32] or by adding reactive bifunctional acid derivatives to the polymerization process accompanied by a decrease in reaction control. These include bending stiffness measurements via Laser Doppler vibrometry 11 or dynamic vibroscope measurements 12,13 based on resonance frequency methods, 14 as well as three-point bending via atomic force microscopy.…”

“…[18][19][20][21][22] This is reasoned in the polycondensation process of polyesters, where degradation dominates the polymerization reaction at high molecular weights. [23][24][25][26][27][28] The result is a low melt strength, limiting the use for several processes. 20,21,26 High molecular grades can be gained by solid-state polycondensation, which needs high reaction times (of several hours) and high costs in large-scale production [28][29][30][31][32] or by adding reactive bifunctional acid derivatives to the polymerization process accompanied by a decrease in reaction control.…”