Poly(vinyl chloride) (PVC) which has chlorine was blended with acrylonitrile-butadiene-styrene (ABS) terpolymer in different ratios by a melt blending technique to give flame retardancy of ABS resin without bromine type flame retardants. ABS powders containing three different levels of butadiene content were used. The weight ratio of PVC in ABS/PVC blends should be higher than 60wt% to prove UL 94 V-0 grade flame retardancy. The initial thermal degradation behavior of ABS/PVC blends was similar with PVC resin. As a result, when the processing temperature is lower than 210℃, the problem of thermal degradation during compounding will be settled. When the contents of butadiene in ABS/PVC blends were 16∼18wt%, maximum impact strength of ABS/PVC blends was obtained which is higher than that of ABS itself. Impact strength of (ABS+SAN)/PVC(4/6) blend was reduced greatly when the contents of butadiene in (ABS+SAN) was 29∼25.6 wt%. According to SEM photographs, fine and harsh fractured surface of ABS/PVC blends showed high impact strength. Flowability of (ABS+SAN)/PVC(4/6) blend was increased linearly according to the contents of SAN when the butadiene contents in (ABS+SAN) was lower than 32 wt%. (ABS+SAN)/PVC(4/6) blends in which 29 wt% of butadiene contents in (ABS+SAN) phase are attractive not only due to their high impact strength but also offer "built in" flame retardancy, moderate cost, good processability, etc.

고가인 브롬 타입의 난연제 첨가없이, ABS 수지에 난연성을 부여하기 위하여 염소를 함유하고 있는 PVC를 ABS와 비율을 달리하면서 용융 블렌딩 하였다. ABS 분말은 부타디엔 함량이 다른 3종을 사용하였다. ABS/PVC 블렌드에 UL 94 V-0급 난연성을 부여하기 위해서는 60wt% 이상의 PVC를 사용하여야만 하였다. ABS/PVC 블렌드의 초기 열분해 거동은 PVC 수지와 유사하였다. 가공온도가 210℃ 이하이면 컴파운딩 과정에서 열분해에 의한 문제점은 해소되었다. ABS/PVC 블렌드에서 부타디엔 함량이 16∼l8wt%일 때 ABS 수지 자체의 충격강도보다 높은 최대 충격강도를 얻을 수 있었다. (ABS+SAN)/PVC(4/6) 블렌드의 충격강도는 (ABS+SAN)의 부타디엔 함량이 29∼25.6 wt% 사이에서 현저하게 감소하였으며 유동성은 부타디엔 함량 32wt% 이하에서 SAN 투입량에 비례하여 증가하였다. (ABS+SAN)의 부타디엔 함량 29wt%인 (ABS (powder A)+SAN)/PVC(4/6) 블렌드가 충격강도, 유동성, 인장특성, 굴곡특성에서 기존의 ABS 난연 grade보다 우수한 특성을 나타내어 최적화된 조성물로 평가되었다.

Keywords: ABS/PVC blends; flame retardancy; impact strength; butadiene contents