In this work, the innovative starch microcapsules enclosed with hydrophobic carnauba wax were developed, which were applied to the modification of cellulose fibers, thus increasing the water resistance of paper by reducing water vapor transmission rate (WVTR). Carnauba wax being encapsulated by crosslinking starch was confirmed by thermogravimetric analysis. The sizes of carnauba wax-starch microcapsules depended on the weight ratio (R) of starch to carnauba wax and concentration of crosslinker. The best performance on water vapor barrier of the paper was achieved by the fibers treated with the microcapsules of larger size. The lowest WVTR was given by the handsheet treated by wet-end addition with carnauba wax-starch microcapsules at Rstarch/ carnauba wax=5%, and R crosslinker/ carnauba wax=50%, and had a value of 348 g/m2day, a 70% drop from untreated original paper which has a WVTR value of 1176 g/m2day.

Poly (butylenesadipate-co-terephalate) (PBAT) was modified by melt grafting glycidyl methacrylate (GMA) in the presence of benzoyl peroxide (BPO) in a Haake mixer; and the various properties of blends of PBAT/thermoplastic starch (TPS) using GMA-grafted PBAT (PBAT-g-GMA) as compatibilizer were investigated. The blends comprising TPS content ranged from 20wt% to 50wt%. Thermal properties and thermal stability were characterized with DSC and TGA, respectively. The morphologic results indicated that the interfacial adhesion of PBAT/TPS blends was improved by PBAT-g-GMA. In comparison with the uncompatibilized blends, the tensile properties of compatibilized blends were significantly enhanced, particularly at a high content of TPS (i.e., 40wt% and 50wt%).

A thermal-responsive polymer was prepared by partially acetalyzing poly(vinyl alcohol) (PVA). The completely reversible polymer aggregation and dissolution occur above and below a low critical solution temperature (LCST) for the aqueous solution of the modified PVA. The partially acetalized PVA (APVA) with higher molecular weight and higher degree of acetalysis exhibited a lower LCST transition and was used as an anionic polymer for polymer complexation. Water-soluble polymer, cationic polyhexamethylene guanidine hydrochloride (CPHGH) with antimicrobial property, was also prepared. In conjunction with APVA, CPHGH created the unique antimicrobial polymer multilayers on the surfaces of rayon fibres via layer by layer (LbL) assembly. AFM images revealed that the particles generated by multilayers became larger after the material was treated at 60°C; while the roughness of the surfaces was increased as the layer number increased and then decreased. Moreover, antimicrobial tests also demonstrated that the rayon fiber assembled with (CPHGH/APVA) multilayers exhibited higher antimicrobial activity against E. coli and s. aureus.

Two approaches of improving the toughness of polypropylene (PP)-based composites reinforced by natural cellulose fibers were developed. The surface modification of cellulose fibrils (CMF) or fiber by either in-situ grafting polymerization of butyl acrylate (BA) on CMF surface via an atom transfer radical polymerization (ATRP) or adsorbing the cationic polymeric latex with core-shell structure on fiber surfaces was performed; and resulting fibers or CMF were used as reinforments in an attempt to enhance the toughness of the PP-based composites. The results of mechanical properties indicated that the flexure, tensile, and impact strengths of the CMF-g-PBA reinforced composites were all improved. The cellulose fibres treated by cationic latex also showed the same trend. The optimal dosage of latex for hydrophobic-modifying fibers was also identified.

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