Study on Relationship between Molecular Orientation and Dynamic Viscoelasticity of Polycarbonate

doi:10.19491/j.issn.1001-9278.2021.09.013

Abstract

Abstract:

Bisphenol?A polycarbonate （PC） plates were prepared through precision injection molding. Based on the relationship between residual flow?induced stresses and molecular orientation， an optical birefringence method was used to investigate the average molecular orientation of the PC plates， and their dynamic mechanical properties were also studied. The experimental results indicated that the plate samples near the gate had a larger molecular orientation than those far from the gate. There is a certain relationship between the orientation and dynamic viscoelasticity. When the loss modulus （tan δ） was selected to be 1， the larger the birefringence， the smaller the dynamic viscosity. This means that the samples with large orientation have small viscosity. When the storage modulus at the end of the glassy platform was selected， the elasticity of the PC plates increased with an increase in orientation， although the dependency was not obvious due to the interference from free volume.

Key words: polycarbonate, molecular orientation, viscoelasticity, storage modulus, loss modulus

CLC Number:

TQ323.4⁺1

LUO Fei, LI Cuijuan, LIU Zhuojia, LIU Yuxin, SHI Suyu, DANG Xudan, LIU Chuntai, ZHAO Yongtao. Study on Relationship between Molecular Orientation and Dynamic Viscoelasticity of Polycarbonate[J]. China Plastics, 2021, 35(9): 81-86.

Figures/Tables 9

Fig.1. Schematic diagram of the PC samples for DMA and birefringence measurement.

Fig.2. The typical birefringence image of PC molded plates

Fig.3. The planar birefringence of PC molded plates

Fig.4. The planar birefringence of PC molded plates

Fig.5. The temperature dependent of loss modulus and tanδ curves of PC samples

Fig.6. Typical tanδ?temperature curve and the threshold point of PC

Fig.7. The relationship between birefringence and loss modulus of PC molded samples

Fig.8. The temperature dependent of storage modulus curves of PC samples

Fig.9. The relationship between birefringence and storage modulus of PC molded sample

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