Saovanee Kovuttikulrangsie and Taweesak Khongkot

pp. 577 - 593

Abstract

Deproteinized natural rubber latex (DPNR) was prepared using KAO protease enzyme to digest
proteins from natural rubber low ammonia concentrated latex (NR-LA). Polystyrene latex (PS) was synthesized by emulsion polymerization technique for blending with natural rubber. The maximum fraction of PS
blended NR-LA or DPNR used to obtain a homogenous film was 20% w/w. The 300% modulus of PS blended
NR film was increased before and after aging at 100ºC for 22 hrs. The tensile strength and elongation at
break were increased at NR/PS = 95/5 w/w and tended to decrease as PS blended fraction increased. DPNR
films had a lower friction coefficient than NR-LA films. PS blended NR-LA or DPNR would decrease the
friction coefficient of films. The rubber-surfaced friction is reduced. The extractable protein of NR-LA film
was higher than 200 µg/g whereas that of DPNR film was lower than 50 µg/g. PS blended NR-LA and DPNR
could reduce the extractable protein to less than 60 µg/g and 30µg/g, respectively. The physical properties of PS blended NR-LA met ASTM D3577 and ASTM D3578 standards for dipping products of surgical gloves
and examination gloves at the maximum fraction of PS 15% w/w and 20% w/w, respectively, whereas PS
blended DPNR only met ASTM D3577 standard at the maximum fraction of PS ≤ 5% w/w.