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In recent years, the growing environmental awareness has prompted increased attention towards the substitution of nonrecyclable thermosetting epoxy resin composite materials with recyclable thermoplastic composite materials. The objective of this study is to utilize a laboratory‐made polymethyl methacrylate (PMMA)/methyl methacrylate (MMA) binary liquid resin (PMBLR) to prepare thermoplastic resin/glass fiber (GF) composite materials using the vacuum‐assisted perfusion method. These composites are then compared with GF‐reinforced thermosetting epoxy resin composites. The investigation reveals a significant influence of benzoyl peroxide (BPO) content on the mechanical properties of pure MMA and PMBLR casting resins, which also incorporate N‐methyl‐N‐((1‐methyl‐1H‐indol‐3‐yl) methyl) aniline (DMA) as redox composite initiators. The optimal mechanical properties for both types of casting resins are achieved at a DMA:BPO:MMA ratio of 0.5:1.2:100. Additionally, at a PMMA concentration of 24 wt% in PMBLR under this specific initiator ratio, the composites demonstrate the most desirable properties. Furthermore, a comparative analysis of PMBLR/GF composites and epoxy/GF composites indicates that the former exhibit superior 90° tensile strength, bending strength, and short beam shear strength. The fracture morphology analysis highlights discernible micro‐ductile fracture characteristics in PMBLR/GF composites, distinguishing them from epoxy/GF composites. Dynamic thermomechanical analysis (DMA) results further reveal a higher storage modulus and loss factor in PMBLR/GF composites when compared to epoxy/GF composites. Highlights: Glass fiber‐reinforced composites were fabricated at ambient temperature.A degradable PMMA/MMA binary thermoplastic resin (PMBLR) was developed as a replacement for non‐degradable epoxy.PMBLR composites exhibit enhanced strength compared to epoxy: tensile (+18.8%), bending (+27.4%), and short beam shear (+34.3%). [ABSTRACT FROM AUTHOR]

Background and purpose: This study was conducted with the aim of investigating parallel strand lumber (PSL) made from reed residue and laminated veneer lumber (LVL) obtained from poplar wood reinforced with glass fiber reinforced polymer (FRP) using epoxy resin. Materials and methods: The independent variable was FRP reinforcement for either LVL or PSL and control sample either LVL or LSL without FRP. The mechanical properties of the manufactured boards including bending strength (MOR) and modulus of elasticity (MOE) in the width and edge of the test sample, shear strength, compression strength parallel to the grain, internal bonding and screw withdrawal strengths were investigated as dependent variables. The obtained results were analyzed using completely randomized design and SPSS software. Results: Results showed that for all studied mechanical properties, the use of FRP increased the strength the PSL and LVL panels. For LVL, the effect of strengthening the samples with FRP was significant at the level of 1% and also for the modulus of rupture of the width and edge samples showed an increase of 93% and 59%, respectively. The value of MOE for samples reinforced with FRP showed an increase of 89.6 and 132% for the width and length of the PSL samples, respectively. For LVL, the MOE value of the width and edge of the samples increased by 54 and 95.5% with reinforcement. Reinforced PSL samples have improved shear strength by 31%, while this value was only 2.5% for LVL. In case of internal bonding, reinforcement with FRP improved the internal bonding strength of the samples by 92%. Screw withdrawal strengths improved by 27% due to the strengthening of the test samples by FRP. Conclusion: According to the results, it can be stated that the use of glass fibers and epoxy resin has a significant positive effect on the mechanical strength of PSL made of reed and LVL and it is possible to use low quality raw materials such as reed and low quality poplar wood layers. [ABSTRACT FROM AUTHOR]

The pull-out method was used to study the adhesive strength τ of "fiber–thermoset" systems with wide variations in area. Studied binders were based on resins that had different chemical natures (epoxy, epoxy phenol, orthophthalic, polyphenylsiloxane, and phenol–formaldehyde). Shear adhesive strength was determined for systems with two fiber types (glass and steel fibers). It was shown that strength τ depended on scale (area). Formation of τ occurred during the curing process and the system's subsequent cooling to the measurement temperature T. It was found that interface strength depended on measurement temperature across a wide temperature range that covered the highly elastic and the glassy state of the adhesive. The influence of residual stresses τres, acting at the "binder–fiber" interface, on the nature of the curves describing the dependence of the adhesive strength on the studied factor was experimentally shown. A qualitative explanation of the observed regularities is proposed. [ABSTRACT FROM AUTHOR]

Glass fibers (GFs) are frequently employed as reinforcement fibers for polymer resins such as epoxy and polyester. The mechanical behaviors of GFs polymer composites are nevertheless constrained by weak interfacial adhesion between polymer matrix and GFs. Herein, we invented a cross‐linking modified sizing agent using polyethyleneimine and bisphenol A epoxy emulsion, and studied the effect of cross‐linking extent on GF surface characteristics and GF/epoxy interfacial adhesion. The treatment of GFs with cross‐linking modified sizing agent facilitated the formation of interpenetrating polymer networks in composites for strengthening interface interaction. The results show that the modified GFs have a rough surface and improved interfacial adhesion with epoxy matrix. When sizing agents with cross‐linking extent of the 23.0%, the GF/epoxy composites show advanced interfacial shear strength (IFSS) and transverse fiber bundle tension (TFBT) strength. This work demonstrates that the cross‐linking extent of sizing agent could regulate interfacial adhesion, which is a facile and promising strategy in reinforcing glass fiber polymer composites. Highlights: Crosslink the sizing agent to enhance GF mechanical properties was reported.GF surface energy was enhanced and thickness of GF/epoxy interphase increased.IFSS and TFBT strength of the GF/resin composites increased by 23.65% and 30.54%, respectively. [ABSTRACT FROM AUTHOR]