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The objective of this paper is to research fiber distribution and mechanical behavior (tensile, flexural, and Charpy impact properties) of long fiber reinforced thermoplastic (LFT) plates made by injection molding. The plates were made of long glass fiber reinforced polyamide 6,6 granules and injected using two types of molds, including center‐gated and end‐gated injecting modes, to obtain different fiber orientation state. In addition, end‐gated plate was cut along three directions (0°/45°/90°) to main flow path, in order to experimentally investigate the effects of fiber orientation on mechanical properties. It is found that there is skin‐shell‐transition‐core structure across thickness of plate, resulted from different fiber orientation. Furthermore, end‐gated plate has more obvious fiber orientation at shell and core regions than center‐gated plate. The experimental results demonstrate that fiber orientation has significant effects on modulus, strength, toughness, and full‐field strain evolution. Tensile and flexural properties decrease by over 50%, as the cutting angle with respect to flow direction changes from 0° to 90° in end‐gated plate. Moreover, unnotched and notched strength drops by 66% and 33%, respectively, from 0° to 90° off‐axis angle. These results show apparent mechanical anisotropy of LFT. Shell‐core structure also significantly influences strain distribution and fracture morphology. [ABSTRACT FROM AUTHOR]

For hollow composite with complex shape, thermal expansion process is usually used to ensure uniform compaction pressure and excellent processing quality. This study focused on compaction of carbon fiber/epoxy matrix composite joint with variable cross‐section using thermal expansion process. Three kinds of silicone rubber core molds were adopted and experiments were performed to study the effect of elastomer core mold on resin pressure distribution inside prepreg stack during process and processing quality of composite joint. Moreover, based on numerical analysis, thermal expansion behaviors of different core molds and compaction pressure on prepreg stack were studied. The results indicate that material properties and geometric structure of core mold significantly influence thermal expansion behavior of core mold and compaction pressure distribution on prepreg stack. Due to irregular shape of core mold, thermal expansion of core mold at the regions with different cross‐sections is obviously uneven. And core mold with large coefficient of thermal expansion and small compressive modulus is more likely to fill process gap and achieve uniform compaction pressure distribution on prepreg stack. Therefore, controlling thermal expansion behavior of core mold to improve processing quality of composite involves reasonable material properties of core mold and adjusting process gap at different cross‐sections of composite. POLYM. COMPOS., 40:E1057–E1074, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Continuous basalt fiber (BF) reinforced epoxy matrix composites with different contents of micro‐tungsten powder were fabricated by hot‐press process with prospective of combined radiation shielding and mechanical functions. Gamma photon shielding and mechanical properties of the composites were evaluated. The measured mass attenuation coefficient shows that tungsten filler significantly improves the radiation shielding property of BF composite, especially for low and moderate photon energies of 80 and 356 keV. Flexural strength of BF composite decreases along with increasing tungsten concentration, while flexural modulus and interlaminar shear strength are not obviously affected by tungsten content. Given the advantages of lightweight, high mechanical property and good radiation shielding performance, the studied BF/tungsten composite is promising material with integrated shielding and structural properties for use in nuclear industry. POLYM. COMPOS., 39:E2106–E2115, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A strong and tough carbon nanotube (CNT)/epoxy composite was fabricated by resin solution impregnation process based on floating catalyst chemical vapor deposition (CVD)-growth CNT films, which had a tensile strength and toughness of 405 MPa and 122 J/g, respectively, and good damping properties as well. Evolution of the composite structure revealed that the CNTs aligned along the tension direction with decreasing orientation angle, and the CNT bundle size enlarged during the tensile test process, which contributed to efficient load transfer among the composite network. Results showed that the proper resin content could bring benefit for strong connections and dense packing of CNTs/bundles, but excessive resin content was unfavorable for improving mechanical properties and conductivities of the nanocomposite. In addition, the resin in CNT film/epoxy composites had a lower crosslink density than that in a neat epoxy system, which endowed the CNT composites with large deformation capability. POLYM. COMPOS., 38:588-596, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The influence of sizing agent on interfacial shear strength (IFSS) of carbon fiber/epoxy (CF/EP) and carbon fiber/bismaleimide (CF/BMI) was investigated. Since sizing agent can alter physicochemical properties of CF surface, possible affecting factors, including sizing reactivity, chemical reactions between sizing and resin, wettability of fiber with resin, fiber surface roughness, and chemical composition of fiber surface, were discussed. It is found that contact angle of fiber with resin and sufficient chemical reactions between sizing and resin reveal strong correlation with the interfacial adhesion of CF/EP and CF/BMI, while the effect of surface roughness and the amount of oxygen on the fiber surface are relatively weak. Due to EP type of the composition, the sizing agent tends to improve the wettability of CF with EP, while goes against for the fiber with BMI. [ABSTRACT FROM AUTHOR]