Study on in situ reinforced composites of thermoplastic resins

Abstract

Typical crystalline thermoplastic resin polypropylene (PP) and amorphous thermoplastic copolymer acrylonitrile-butadiene-styrene (ABS) were respectively blended with selfmade novel low-melting point thermotropic liquid crystalline polyester (TLCP) that contained phosphorus and nitrogen elements (PN-TLCP). Then, the PP/PN-TLCP and ABS/ PN-TLCP in situ-reinforced composites were prepared. The effects of PN-TLCP on mechanical property, microstructure, processability, and thermal stability of these two composites were investigated. The results showed that the strength and rigidity of matrix were improved, indicating that PN-TLCP played a role of enhancement. Meanwhile, PN-TLCP could form microfibrillar structure in PP and ABS matrix, which was the main reason of the formation of in situ composites. In the forming process, PN-TLCP could induce PP resin to form -crystal, which was why the toughness of PP was improved. In addition, PP and ABS exhibited better processing flowability and their melt flow rates were respectively increased 18% and 56% after blending with PN-TLCP. Besides, PN-TLCP was highly beneficial to improving the thermal stabilities of matrix. Various tests showed that this kind of TLCP was suitable for crystalline thermoplastic resin PP and its composites would have more outstanding comprehensive properties.

Design and Synthesis of Polysiloxane Based Side Chain Liquid Crystal Polymer for Improving the Processability and Toughness of Magnesium Hydrate/Linear Low-Density Polyethylene Composites

“…It is deduced that the molecules of PSCTLCP are oriented in the shear direction during the melt processing when the enough shear force exists. The larger the shear force, the easier the orientation of PSCTLCP and the better the processability [21][22][23]. Figure 6b shows the balance torque vs. temperature curves for MH/LLDPE and PSCTLCP-1.0 at 50 rpm.…”

“…During the melting process, the rigid TLCP macromolecules are easily oriented and arranged along the flow direction under the action of shear or tensile force, and ultimately improve the processability of thermoplastic composites [17][18][19][20].However, for TLCP, the prerequisite for improving the processability of thermoplastic composites is that the liquid crystal phase transition temperature range is consistent with the processing temperature of thermoplastics [21]. Unfortunately, at present, the melting temperature of most main chain thermotropic liquid crystal polymers is quite high and is just comparable to that of the engineering plastics with high processing temperature [22], but is not well matched with the polyolefins with lower processing temperature [23]. Therefore, it has attracted more and more attention to reduce the melting point of the thermotropic liquid crystal polymer and further to expand its application in polyolefin-based thermoplastic composites with lower processing temperature [24].…”

Aging Mechanism and Lifetime Prediction of Glass Fiber Reinforced Liquid Crystal Polymer Composite under Thermal and Oxidative Conditions

“…LCP can also be processed into sheets with a proper coefficient of thermal expansion (CTE), providing resistance to chemicals, lower moisture absorption, surface roughness for copper lamination adhesion, mechanical flexibility, and availability in various thicknesses (25-180 μm). [15,[24][25][26][27][28][29] With these properties, LCP is an ideal material for electronic components such as micro-connectors, integrated circuit (IC) devices, and conformal antennas used in high-frequency applications. [30][31][32] In particular, in the flexible board process, LCP is expected to replace polyimide (PI) as the next-generation dominant product for high-frequency applications (above 5 GHz).…”

Grafting of thermotropic fluorinated mesogens on polysiloxane to improve the processability of linear low-density polyethylene

“…16 Therefore, reducing the melting point of TLCPs is highly desirable to broaden their application. 17 On the other hand, ameliorating the melt fracture and reducing the extruder head pressure are also crucial to improve the polyolefins production efficiency. These improvements can be potentially achieved by integrating fluorinated compounds on TLCPs due to their excellent lubricating properties for processing thermoplastic materials.…”