Poly(p-hydroxybenzoate)(PHB)/poly(ethylene terephthalate)(PET) 8/2 thermotropic liquid crystalline copolyester, poly(ethylene 2,6-naphthalate)(PEN), and PET ternary blend was spun to fiber by melt spinning process, and tensile properties of the fibers were measured. The matrix of the fibers, PET and PEN, were dissolved in o-chlorophenol at 55 ℃ for 2 hours, and the liquid crystalline polymer fibrils were observed using a scanning electron microscope. Halpin-Tsai equation for modulus calculation of short fiber reinforced composite and the rule of mixture for continuous reinforcement composite were modified, and the tensile modulus were calculated and compared with experimental modulus. To minimize difference between the theoretical and the experimental moduli, dimensionless viscosity constant(K) was given and used to modify two equations. The theoretical tensile modulus using the newly modified equations presentel a similar to the experimental tensile modulus of composite, and the modified equations presented a unique way to determine the tensile modulus of the liquid crystalline polymer reinforced thermoplastic composites.

Poly(p-hydroxybenzoate)(PHB)/poly(ethylene terephthalate)(PET) 8/2 공중합 폴리에스터 액정고분자와 poly(ethlylene 2,6-naphthalate(PEN), PET를 용융방사하여 인장탄성률을 측정하고, 55℃ o-chlorophenol에서 2시간 동안 모재인 PEN/PET 부분을 용출시킨 후, 용출되지 않은 PHB 피브릴을 전자현미경으로 조사하였다. 모재고분자 속에 존재하는 피브릴이 단섬유일 때 적용하는 Halpin-Tsai식과 피브릴이 연속상일 경우 적용하는 혼합의 법칙을 사용하여 이론적인 탄성률을 계산하고, 측정된 탄성률과 비교하였다. 이론적 탄성률과 축정된 탄성률의 차이를 보정하기 위하여 무차원 점도비 상수(K)를 정의하고, K를 적용하여 기존의 식을 변형하였다. 변형된 Halpin-Tsai식과 혼합의 법칙을 통해 계산된 이론적인 탄성률은 용융방사를 통해 제조된 복합재료의 탄성률 계산에 더 적합함을 확인하였다.

Keywords: liquid crystal polymer; PEN; PET; Halpin-Tsai equation; rule of mixture