Characterization of a fiber reinforced semirigid liquid crystalline polymer

Abstract

Semirigid liquid crystalline polymers (LCPs) show some advantages with respect to rigid LCPs: in particular lower processing temperatures, and better compatibility with flexible thermoplastics, but also some disadvantages: lower mechanical properties and poor thermomechanical resistance. Both properties can be improved by adding inorganic fillers. In this work, samples of a semirigid liquid crystalline polymer reinforced with carbon and glass fibers has been characterized. Although elastic modulus and tensile strength of the glass fiber filled LCP improve remarkably with increasing the filler content, the same properties for the carbon fiber‐filled samples do not increase with increasing the content of the fiber; rather a maximum tensile strength is observed at about 20% of carbon fibers. The thermomechanical and the creep behavior are also drastically improved by adding the fibers. In particular, the creep curve is shifted by several decades toward longer times, and the heat distortion temperature increases about 60°C by adding 20% of carbon fibers. The processability is, on the other hand, significantly worsened. By comparing the results for the carbon fiber‐filled samples with those obtained for the same polymer reinforced with glass fibers, it is worth noting that the properties are similar, but lower amounts of carbon fibers are needed to obtain the same mechanical and thermomechanical properties. © 1997 John Wiley & Sons, Inc. Adv in Polym Techn 16: 227–236, 1997

Influence of fillers on the mechanical response of an amorphous liquid‐crystalline polymer

“…An increase in HDT or other properties, used to measure the temperature resistance, is usually seen in semicrystalline polymers with the addition of fillers. However, amorphous and semirigid LCPs, such as filled amorphous thermoplastics, 18 are much less affected, showing slight increases 11,17 comparable to those of the nonfibrous fillers of this work.…”

Processability and mechanical performance of hybrid composites based on poly(ether sulfone) modified with a glass fiber–reinforced liquid crystalline polymer

“…Their behavior did not depend on the nature of the filler, and the reinforcement was better with fibers than with particulates because of the higher aspect ratio of the former 3. No significant differences were obtained between the properties of LCPs filled with glass or carbon fibers 4, 22…”

“…However, they have some disadvantages,2 such as poor weld strength, weak surface (creating fibrils by rubbing), and strong anisotropy in mechanical properties. The use of fillers in LCPs increases the viscosity3, 4 and decreases the tensile strength 2, 5, 6. However, the filled LCPs show increases in the flexural and tensile modulus, and in thermal endurance associated with incorporation of inorganic fillers, and the required properties of the LCP materials can be promoted while minimizing the unwanted ones 2, 3…”

“…3 No significant differences were obtained between the properties of LCPs filled with glass or carbon fibers. 4,22 Fillers have also been used to reinforce thermoplastic/LCP blends. In most studies, the inorganic reinforcement was added as a third component, [23][24][25][26][27][28][29][30][31][32] but fiber-reinforced matrices, such as glass fiber-reinforced poly(ether imide) (PEI) 33 or PES, 34 have also been used.…”

“…In most studies, the inorganic reinforcement was added as a third component,23–32 but fiber‐reinforced matrices, such as glass fiber–reinforced poly(ether imide) (PEI)33 or PES,34 have also been used. There are many studies of filled LCPs2–6, 22, 35–37 and filled thermoplastic/LCP blends23–33; however, to our knowledge there is no study of thermoplastic/filled LCP composites.…”