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Abstract: Non-isothermal melt- and cold-crystallization and subsequent melting behavior of poly(3-hydroxybutyrate) (PHB) have been investigated by differential scanning calorimetry (DSC). The crystallization kinetics was studied by a direct fitting of the experimental data to various macrokinetic models, namely Avrami, Tobin and Ozawa models. All of the macrokinetic models were found to describe the experimental data for both the melt- and the cold-crystallization processes fairly well. For both the melt- and the cold-crystallization processes, the inversed half-time of crystallization and both the Avrami and the Tobin rate constants were all found to increase with increasing cooling or heating rate. For the melt-crystallization process, the Ozawa rate constant was found to decrease, while, for the cold-crystallization process, it was found to increase, with increasing temperature. Finally, the effective energy barrier for both the melt- and the cold-crystallization processes was found to decrease in its magnitude with increasing relative crystallinity. [Copyright &y& Elsevier]

The antimicrobial thermoplastic starch (ATPS) containing guanidine-based polymers was obtained using a twin-screw extrusion with potato starch and polyhexamethylene guanidine hydrochloride (PHGH). Furthermore, the non-leaching antimicrobial biodegradable poly(butylene adipate-co-terephthalate) (PBAT) was prepared through reactive extrusion with PBAT and ATPS in the presence of the coupling agent, 2,2′-(1,3-phenylene)-bis (2-oxazoline) (PBO). Finally, the antimicrobial PBAT films were obtained by using a blown film extrusion system. The mechanical properties of the antimicrobial PBAT films varied with the contents of ATPS and thermoplastic starch (TPS). According to the test results of shaking flask method, the prepared antimicrobial PBAT films showed excellent antimicrobial activities (antimicrobial rate > 99.99%) and rapid pathogen deactivation efficiency (antimicrobial rate > 99.99% even within 15 s of contact time). The water washing and ring diffusion tests demonstrated that the antimicrobial film was a non-leaching product. Inspiringly, the antimicrobial PBAT films with an excellent antimicrobial activity can be obtained even at a very low dosage of PHGH (1.0 mg/g PBAT film). [ABSTRACT FROM AUTHOR]

Abstract: The cationization of polymers has been regarded as an effective method to improve their performance for various applications. In this work, the cationization of poly vinyl alcohol (PVA) was investigated under different conditions, i.e., various glycidyl-trimethylammonium chloride (GTMAC) to PVA ratios, reaction temperatures, times, PVA and NaOH concentrations and solvent compositions. The results showed that the overall efficiency of the cationic modification was rather low, which was due to the hydrolysis of both GTMAC and cationic-modified PVA (CPVA) under the strong alkaline conditions employed. The results also showed that the optimum GTMAC/PVA ratio depended on the solvent composition. The cationization was confirmed by means of 1H NMR and FTIR analyses. The maximum efficiency in water was obtained under the conditions of 95°C, 1h, 0.5 (mol) GTMAC/PVA ratio, and 5% (mol) NaOH concentration, while that in the ethanol/DMSO mixture (1.25v/v) was obtained under the conditions of 70°C, 1h, 0.5 (mol) GTMAC/PVA ratio, and 5% (mol) NaOH concentration. Additionally, the interaction of CPVAs with a silicon wafer (as a substrate) was determined by employing an atomic force microscope (AFM) in water and air. [Copyright &y& Elsevier]