PHA/PAA 블렌드 제조 및 특성에 관한 연구

Abstract

ABSTRACT

Study on the Preparation and Characterization of PHA/PAA Blends

Duyoung Wee Advisor : Prof. Choi, Jae-Kon, Ph. D. Department of Advanced Parts and Materials Engineering, Graduate School of Chosun University

To enhance the compatibility of polyhydroxyamide (PHA) and poly(amic acid) (PAA) blends, we introduced imide ring into PHA using a direct polymerization method. Then, we prepared the resulting polymer blends and characterized them using FT-IR, 1H-NMR and XRD methods. The thermal properties of the blends were also studied using DSC and TGA; the dynamic mechanical properties were investigated using DMA and UTM. In addition, we also employed an LOI method to study the flame retardancy of the blends. The SEM technique was used to understand the morphology of the blends. The solubility study revealed that the PHA and PAA were soluble in aprotic solvents such as DMAc, DMF, DMSO, and NMP; the inherent viscosities of the PHA and PAA at 35 ℃ in DMAc were in the range of 1.62－2.31 dL/g. It was also found that the PHA and PAA were converted to polybenzoxazole (PBO) and polyimide (PI) by a thermal cyclization reaction at 150－305 ℃. In DSC thermograms, the PHA and PAA showed one endothermic peak at 305 ℃ and 150 ℃, respectively. On the other hand, the blends showed two endothermic peaks in the temperature range of 150－305 ℃. It was also observed that the char yields of the polymer blends were in the range of 32－49 %; the char yield of 2:8 (PHA/PAA) blend was 10 % higher than that of pure PAA. The initial storage moduli of polymer blends measured by DMA were in the range of 9.13－9.71 MPa, and the modulus value increased with increasing PHA content. It was also observed that the initial storage modulus of PHA was 1.1 times higher than that of pure PAA. The initial modulus and tensile strength of polymer blends were in the ranges of 1.00－2.61 MPa, and 46.72－73.21 MPa, respectively; the elongation of the blends increased from 3.9% to 23.6% with increasing PAA content. The 2:8 blend showed higher initial modulus and tensile strength than the pure PAA. The SEM study revealed that the domain size of PHA was 0.03－0.05㎛, and the domains were well dispersed throughout the polymer, which indicated that the interfacial compatibility of the two polymers were improved. It was found that the LOI values of polymer blends were increased with increasing PHA content.