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Glass fiber reinforced polymer-based composites prepared by photocuring technology offer notable advantages. However, the traditional UV curing technology faces challenges in balancing curing efficiency, penetration depth, and mechanical properties when producing high-thickness fiber-reinforced composites. This study introduced a new method for crafting thick glass fiber reinforced composites via upconversion particle-assisted near-infrared photopolymerization (UCAP). Near-infrared (NIR) radiation had superior penetration in glass fiber composites system, effectively curing of specimens exceeding 20 mm in thickness. Through micro-CT and atomic force microscopy, it was verified that UCAP specimens had fewer interfacial defects and a wider interphase, making contribution to enhanced interlaminar and interfacial shear strength. Additionally, uniform curing effectively alleviated stress concentration under external forces, resulting in a 78.5 % increase in flexural strength and a 32.1 % increase in impact toughness for UCAP specimens compared to UV-cured ones. This approach facilitated rapid outdoor curing of large-sized glass fiber composites with sustained structural stability, showcasing the potential application of UCAP in high-performance glass fiber composites rapid prototyping. • Photo curing of high-thickness glass fiber composite using high penetration NIR. • NIR cured composites exhibit enhanced interfacial performance and reduced internal defects compared to UV curing ones. • NIR cured specimens exhibit uniform stress distribution compared to UV curing specimens. • Composites cured by NIR demonstrate higher flexural strength compared to those cured using UV. [ABSTRACT FROM AUTHOR]

Aiming for obtaining flame-retardant vinyl ester resins (VER) and the composite, a kind of liquid 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-containing 1-vinylimidazole salt (called VIDOP) was conveniently synthesized through the neutralization of the DOPO-derived acid and 1-vinylimidazole to be applied as flame-retardant crosslinking agents of VER. Curing behaviors, flame retardancy, thermal decomposition behaviors, thermal-mechanical properties, and mechanical performance of VER materials were investigated. With 25 wt% addition of VIDOP, the modified resin (VIDOP25/VER) and their glass fiber reinforced composites (VIDOP25/VER/GF) achieved UL 94 V-0 rating with a limiting oxygen index value of 32.1% and 38.3%, respectively. Both heat release and smoke release of VIDOP25/VER and VIDOP25/VER/GF decreased compared to those of the reference sample in the cone calorimetry test. VIDOP showed flame-retardant activities in both gaseous and condensed phases for the resin, while they didn't work well in the condensed phase for the composite. VIDOP/VER presented a little lower a glass transition temperature than VER with a relatively low crosslinking density, in which 1-vinylimidazoles covalently linked with the VER chain and the DOPO-derived group attached to the resin via ionic bonds. VIDOP/VER and the composite had better mechanical properties than the unmodified sample and outperform other systems in well-balanced performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Polymer matrix composites have established themselves in the materials family due to their improved properties like high specific stiffness and strength, durability etc. Recycled polyethylene terephthalate (RPET) is being used as matrix material in a variety of polymer matrix composites. Composite materials based on RPET matrix, in addition to being cost effective, are also environment friendly. Use of RPET as matrix material not only reduces the consumption of virgin materials, but it also simultaneously addresses the concern regarding environmental pollution due to post consumer PET waste. This review compiles and critically analyses the efforts of various researchers regarding the influence of; different types of reinforcing materials such as synthetic and natural fibers, micro and nano fillers, blending of RPET with various virgin polymers, on the properties of composite materials based on RPET. [ABSTRACT FROM AUTHOR]