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In this work, an antimicrobial guanidine polymer (PHGH) was grafted onto starch as a carrier to form branched or grafted chains along the starch backbone. This grafting improved the antimicrobial properties and the adsorption of the starch on recycled cellulose fibers. Similar work was also conducted on bleached sulfite fibers for comparison. The results showed that the starch, grafted with 12 wt% PHGH, adsorbed more on recycled fibers than on sulfite fibers. By applying the antimicrobial-modified starch to recycled or sulfite pulps up to 20 mg/g, both antimicrobial and antimold performances of the papers were improved substantially. Additionally, the PHGH-modified starch increased the tensile index of papers, but decreased the tear index slightly. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to investigate the morphologic changes of Escherichia coli bacteria and Chaetomium globosum fungi upon exposure to the PHGH-modified starch, thus demonstrating that the antimicrobial mechanism is based on the damage of bacterial membrane. [ABSTRACT FROM AUTHOR]

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]

Antimicrobial packaging films havebeen widely used in variousapplications. However, because of concerns regarding safe food andconsumer demands for preservative-free products, the antimicrobialagents applied to packaging have to be highly effective and the leachingeffect is not allowed. In the present work, the antimicrobial agentpolyhexamethylene guanidine hydrochloride was compounded with starchto prepare antimicrobial thermoplastic starch (ATPS). ATPS was thenmelt-blended with linear low-density polyethylene (LLDPE) to preparethe novel antimicrobial packaging film. The resultant LLDPE/ATPS filmsexhibited excellent antimicrobial properties against Escherichiacoliin the shaking-flask test. The ring-diffusion test furtherconfirmed the nonleaching effect of the films. However, the additionof ATPS decreased the crystallinity of LLDPE. Both rheological analysisand scanning electron microscopy images indicated that a high ATPScontent might result in poor compatibility even in the presence ofa compatibilizer. [ABSTRACT FROM AUTHOR]

A series of comb-like ionenes (C-ionenes) with aliphatic side chains were prepared via the Menschutkin reaction from amine, epichlorohydrin, and N, N, N′, N′-tetramethyl-1,6-hexanediamine. The structures of the resulting ionenes were characterized by means of charge density, H-NMR, and C-NMR. The antimicrobial properties of the ionenes were also investigated by measuring the minimum inhibition concentration (MIC) against Escherichia coli ( E. coli). The corresponding antimicrobial dynamics were studied by detecting the UV absorbance of the E. coli suspension. It was found that in comparison to the linear ionenes (L-ionenes), C-ionenes exhibited lower MIC values and faster antimicrobial effect influenced by the side chains. In particular, C-ionene with 4-carbon side chains showed MIC at 7.8 μg/mL and its aqueous solution (31.2 μg/mL) inhibited 99.9 % E. coli within 2 min. The morphologies of C-ionenes in aqueous solution were investigated by measuring their particle sizes and zeta potentials. In addition, the anti-mold tests against Aspergillus niger and Chaetomium globosum suggested that the comb-like ionenes were effective at inhibiting the growth of the fungi. [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]

Abstract: In this work, the diffusion of cationic poly (vinyl alcohol) (CPVA) with well-defined structures into the pores of bleached kraft fibers was investigated at equilibrium level of adsorption by means of adsorption, solute exclusion technique (SET), and nuclear magnetic resonance (NMR) relaxation method. The results showed that the interaction between CPVA and dextran polymers was weak, which allowed us to use the SET method to investigate the variation in the pore size of fibers upon diffusing CPVAs. Both adsorption and SET methods confirmed the diffusion of CPVA polymers into the fiber pores. However, the NMR technique was unable to reflect the pore size changes. The main reason for such results was probably the error that occurred in removing water between fibers via applying the water retention value (WRV) test prior to the NMR analysis. In fact, not all of the water on the fiber surface, especially on the surface of CPVA-modified fibers, could be removed by the WRV, introducing some error in the NMR analysis. [Copyright &y& Elsevier]