Studies on the mechanical and dynamic mechanical properties of thermotropic liquid crystalline polymer/unsaturated polyester/glass fiber in situ hybrid composites

Abstract

In situ hybrid composites of thermotropic liquid-crystalline polymer (TLCP), unsaturated polyester (UP) and glass fiber (GF) have been successfully prepared by melt mixing technology. The mechanical properties and dynamic mechanical properties and the morphologies of these in situ hybrid composites have been studied by static mechanics analysis, dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The static mechanical test results showed that the impact strength and the bending strength, bending modulus, specific strength and specific modulus of the in situ hybrid composites tend to increase with the increase of TLCP content for the composites containing TLCP content below 5%. DMA results indicate that the microstructure of curing network, glass transition temperature and obdurability of composites with TLCP content below 5% have been improved. Scanning electron microscope observations revealed that the interfacial adhesion between matrix and fiber had been improved with the addition of TLCP.

Static and dynamic mechanical properties of flame‐retardant copolyester/nano‐ZnCO3 Composites

“…This phenomenon might be attributed to the introduction of CEPPA, which catalyzed char formation; the char in turn inhibited the combustion and decomposition of PET, and this enhanced the LOI value and UL-94 rating. 17 The LOI values of the PET/nano-ZnCO 3 composites slightly increased with the nano-ZnCO 3 content increasing up to 3 wt %; when 3 wt % nano-ZnCO 3 was added to the PET matrix, the LOI value increased from 23 to 25%. The LOI values of the PET/nano-ZnCO 3 composites were nearly the same as the value of pure PET.…”

“…Pure PET had an LOI value of only 23% and a V2 rating according to the UL‐94 test, whereas PET60, which contained 0.6 wt % phosphorus, had a much higher LOI value (29%) and reached a V0 rating; this indicated that phosphorus had a significant effect on the improvement of the flame retardancy of PET. This phenomenon might be attributed to the introduction of CEPPA, which catalyzed char formation; the char in turn inhibited the combustion and decomposition of PET, and this enhanced the LOI value and UL‐94 rating 17. The LOI values of the PET/nano‐ZnCO 3 composites slightly increased with the nano‐ZnCO 3 content increasing up to 3 wt %; when 3 wt % nano‐ZnCO 3 was added to the PET matrix, the LOI value increased from 23 to 25%.…”

“…Many studies of thermoplastic nanocomposites have revealed that the interfacial adhesion and dispersion characteristics of nanoparticles in composites are greatly responsible for the reinforcement effect of polymer nanocomposites, and they also significantly affect the final mechanical properties (e.g., the modulus and strength). 13,17,19 To determine the relationship between the morphology of PET/nano-ZnCO 3 composites and their mechanical properties, we studied the morphology and nano-ZnCO 3 distribution in the PET and phosphorus-containing copolyester matrix with SEM. Figure 5(a) shows the morphology of nano-ZnCO 3 , and Figure 5(b-f) shows the morphology of pure PET and PET/nano-ZnCO 3 composites.…”

“…6,7,12,13 Dynamic mechanical test methods have been widely employed for investigating the structures and viscoelastic behavior of polymeric materials to determine their relevant stiffness and damping characteristics for some kinds of applications. [14][15][16][17][18][19] The introduction of phosphorus-containing flame retardants and reinforcing fillers into polymers probably affects the storage modulus (E 0 ), loss modulus (E 00 ), and glass-transition temperature (T g ). Therefore, it is necessary to evaluate the effects of nanofillers on the dynamic mechanical properties of polymer composites.…”

Liquid Crystal Polymers

“…37 In addition, the mechanical properties are enhanced. 37 In addition, the mechanical properties are enhanced.…”