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Item type:Publication, Access status: with files , Bio-based poly(furfuryl alcohol) resin as a sustainable matrix alternative for prepregsDespite their ecological superiority and competitive thermo-mechanical performance compared to petrochemical matrices, furan resins based on poly(furfuryl alcohol) (PFA) have so far played a minor role in composite applications. This is due to a demanding manufacturing process, which involves long curing cycles and specialized equipment for removing water from polycondensation to produce low-porosity parts. This work employs resin pre-curing (B-staging) to tailor PFA bio-resin properties for prepreg applications, while reducing the porosity in a fully cured state. A PFA prepolymer with a bio-content of 98 wt% was synthesized before heat treatments were applied for B-staging and final curing of the acid-catalyzed prepreg resin. The influences on viscosity, resin reactivity and chemistry, molecular weight, volatile separation, density, and porosity were investigated. It was found that an isothermal 120-minute B-staging procedure at 60 °C resulted in rheological behavior matching the processing properties of commercial, aerospace-grade epoxy prepregs. It was demonstrated that B-staging reduces volatile separation and associated void formation in the final curing step. Fully cured PFA samples with a porosity of less than 3 % could be produced employing short curing cycles. The findings advance the understanding of sustainable lightweight materials by tailoring PFA resins as potential polymer matrices for bio-prepregs.Publicationtype: Journal Article80 26 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A review on aging effects of thermoset prepregsThermoset prepreg materials have emerged as the composite material of choice for demanding structural applications due to their easy processability and attainable superior part quality. However, the one-part nature of common precured thermoset resins renders prepregs susceptible to undesired premature curing, which may entail deterioration of properties. This article reviews the current state of literature on thermoset prepregs with regard to aging effects that originate before the final cure cycle of composite parts, i.e., during freezer storage and upon temporary storage or processing at room temperature. Therefore, the aging-related evolution of the physio-chemical prepreg state (conversion, Tg, water uptake, viscosity) is examined in terms of its impact on processing (forming properties, tack), applied cure cycles (temperature, dwell time, pressure) and post-cure laminate quality (porosity, mechanical performance). The economic and ecological implications of prepreg aging are discussed in conjunction with recycling strategies for out-of-spec material. Finally, approaches proposed to mitigate out-time effects of prepregs (latent curing agents, cure cycle modification, vitrimer matrices) are presented.Publicationtype: Review Article47 48