The lowering of melt viscosity has been investigated to achieve the processability enhancement in poly(ethylene naphthalate) (PEN) melt processing by the reactive melt blending with poly(ethylene terephthalate) (PET) and introducing lubricant as well. CaST lubricant resulted in the lowering of PEN melt viscosity but noticeable mechanical property drop was found in PEN with more than 2 wt% of lubricant due to the acceleration of thermal degradation by excess lubricant. PEN/PET (90/10) blend has less melt viscosity than PEN and transesterification between two polymers caused the additional viscosity depression. Further viscosity lowering was found in PEN/PET blend with CaST since CaST is acting as the catalyst of transesterification as well as a lubricant in PEN/PET blend.

폴리(에틸렌 나프탈레이트)(PEN)의 가공 특성 향상을 위하여 윤활제 첨가와 폴리(에틸렌 테레프탈레이트)(PET)와의 블렌딩에 의한 상호에스테르 교환반응 유발에 따른 용융 점도 변화에 대하여 고찰하여 보았다. PEN에 윤활제로 calcium stearate(CaST)를 첨가한 결과, 점도를 낮출 수 있었으나 2 wt% 이상의 CaST 첨가는 PEN의 열분해를 촉진하여 기계적 물성이 현저히 감소됨을 확인하였따. PEN에 PET를 10 wt% 첨가하여 상호에스테르 교환반응을 유발시킨 PEN/PET 블렌드는 PEN보다 낮은 점도를 가지며 이에 1 wt%의 CaST 윤활제를 같이 첨가하면 CaST가 윤활제 역할을 하는 동시에 상호에스테르 교환반응 촉진제로 작용하여 추가적인 점도 감소가 일어남을 확인하였다.

Keywords: poly(ethylene naphthalate); rheological property; calcium stearate; blends; transesterificcation