Suitable semi-batch reaction conditions are determined to maximize the fraction of acrylate chains with TDBs while also achieved a target polymer molar mass.

In the present study poly (butylene sebacate-co-terephthalate)s having different compositions were synthesized with a high yield and a random distribution by thermal transesterification of poly (butylene sebacate) and poly (butylene terephthalate) homopolymers. The copolymer with the highest comonomer ratio was the least crystalline sample, although the melting peaks corresponding to both, sebacate and terephthalate-rich phases were still observable in calorimetric heating runs. This copolymer was associated with interesting thermal and mechanical properties, as the maximum melting point was higher than 100 °C and the storage modulus was also high (i.e. 1.1 × 109 N/m2 and 1.7 108 N/m2 were determined just before and after the main glass transition temperature of -12 °C).\ud \ud As all studied samples were thermally stable up to temperatures clearly higher than the fusion temperature, they could be easily processed. Increasing the terephthalate content of the copolymers resulted in higher hydrophobicity, which had a minor influence on cell adhesion and proliferation of both fibroblast-like and epithelial-like cells. Hydrolytic and enzymatic degradability were assessed and the effect of composition and crystallinity on the degradation rate was investigated. Molecular weight measurements during exposure to a hydrolytic media indicated a first order kinetic mechanism during the initial stages of degradation before reaching a limiting molecular size, which was indicative of solubilization. The most amorphous sample appears as a highly promising biodegradable material since it showed a significant weight loss during exposure to all selected degradation media, but also exhibited good performance and properties that were comparable to those characteristic of polyethylenePeer ReviewedPostprint (author's final draft

Secondary reactions significantly affect acrylate polymerization rates as well as the architecture of polymer produced by high‐temperature solution radical polymerization. This impact is amplified under the semi‐batch starved‐feed policy used to keep monomer concentration low. Thus, the importance of intramolecular chain transfer (backbiting) is significantly increased, generating a tertiary radical center capable of termination, propagation, and scission. In this investigation, a comprehensive stochastic model is formulated to represent results from an experimental study designed to increase the fraction of reactive terminal double bonds (TDB) in the poly(butyl acrylate) product. Model predictions generated using three sets of literature kinetic parameters for backbiting and scission are compared. While each provides reasonable predictions of some reaction characteristics (e.g., free monomer levels, polymer molecular weights, polymer TDB content), none provide an adequate representation of all aspects of the polymerization. It is concluded that other reaction pathways might be needed to represent the system under semi‐batch conditions, thus explaining the discrepancies seen among the current parameter estimates.

Nanocomposites of poly(butylene terephthalate) (PBT)/modified montmorillonite organoclay were prepared via in-situ polymerization of terephthalic acid and butanediol in the presence of different clay content. Cloisite 30B, a commercially available amino modified montmorillonite, was modified with 3-aminopropytriethoxysilane (APS) through a silylation reaction. Morphology and properties of all samples were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ( 1 HNMR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The extent of clay layers in samples was confirmed by XRD. Results of XRD and TEM showed that an exfoliation structure was produced in nanocomposites. Studies of crystallization showed that the presence of nanoclay leads to an increase in the crystallization rate and enhances the thermal stability of nanocomposites. Crystallization kinetics were described by the Avrami equation. Crystal growth was spherulitic. According to dynamic mechanical analysis (DMA), storage modulus of nanocomposites was remarkably improved compared with homo PBT. Moreover, a shrinkage test was carried out. Results showed a reduction in shrinkages along and across the flow direction that means a decrease in free volume. Flammability based on the UL-94 test was applied to study the flame retardancy effect of nanoclay on the samples.

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