Kuo-Shien Huang

Ultradrawing properties of ultrahigh molecular weight polyethylenes/functionalized activated nanocarbon as-prepared fibers

The improvement of the ultradrawing and ultimate tensile properties of high performance fibers is the most critical and challenging for applications of high performance fibers, such as ultra high molecular weight polyethylene (UHMWPE) fibers. This paper aims to improve the ultradrawing and ultimate tensile properties of UHMWPE fibers by incorporating very small amounts of nanofillers during the gel spinning process of UHMWPE fibers. Activated nanocarbon (ANC), acid treated activated nanocarbon (ATANC) and functionalized activated nanocarbon (FANC) prepared by grafting maleic anhydride polyethylene onto ATANC, were added into the UHMWPE fibers as effective nucleation nanofillers with specific surface areas higher than 1000 m2 g−1. This is the first work where ANC, ATANC and FANC were used as reinforced or functional additives in UHMWPE composite fibers to enhance their ultradrawing and/or ultimate tensile properties. The experimental results show that the maximum achievable draw ratio obtained for the best prepared UHMWPE/FANC fiber reaches 398 and the ultimate tensile strength (σf) of the best prepared UHMWPE/FANC drawn fiber reaches around 7.8 GPa, when the mass fraction of FANC is 0.075 phr. They are the highest draw ratios and σf values obtained so far for UHMWPE/nanofiller composite fibers reported in the literature.

Mechanical Retention and Waterproof Properties of Bacterial Cellulose-Reinforced Thermoplastic Starch Biocomposites Modified with Sodium Hexametaphosphate

The waterproof and strength retention properties of bacterial cellulose (BC)-reinforced thermoplastic starch (TPS) resins were successfully improved by reacting with sodium hexametaphosphate (SHMP). After modification with SHMP, the tensile strength (σf) and impact strength (Is) values of initial and conditioned BC-reinforced TPS, modified with varying amounts of SHMP(TPS100BC0.02SHMPx), and their blends with poly(lactic acid)((TPS100BC0.02SHMPx)75PLA25) specimens improved significantly and reached a maximal value as SHMP content approached 10 parts per hundred parts of TPS resin (phr), while their moisture content and elongation at break (ɛf) was reduced to a minimal value as SHMP contents approached 10 phr. The σf, Is and ɛf retention values of a (TPS100BC0.02SHMP10)75PLA25 specimen conditioned for 56 days are 52%, 50% and 3 times its initial σf, Is and ɛf values, respectively, which are 32.5 times, 8.9 times and 40% of those of a corresponding conditioned TPS100BC0.02 specimen, respectively. As evidenced by FTIR analyses of TPS100BC0.02SHMPx specimens, hydroxyl groups of TPS100BC0.02 resins were successfully reacted with the phosphate groups of SHMP molecules. New melting endotherms and diffraction peaks of VH-type crystals were found on DSC thermograms and WAXD patterns of TPS or TPS100BC0.02 specimens conditioned for 7 days, while no new melting endotherm or diffraction peak was found for TPS100BC0.02SHMPx and/or (TPS100BC0.02SHMPx)75PLA25 specimens conditioned for less than 14 and 28 days, respectively.