For the first time ever, a styrene-free, biobased formulation suitable for infusion processing of thermoplastic composites is reported. Biobased polylactide (PLA) is soluble in methyl methacrylate (MMA) and this new styrene free system is suitable for fabricating composite parts. Rheology is critically important in transfer molding; therefore, single chain properties are related to concentrated solutions of PLA in MMA. Multiple angle laser light scattering (MALLS) provides molecular weights, radii of gyration, and second virial coefficients for PLAs of varying molecular weight dissolved in MMA. The Flory interaction parameter is described by χ = 0.40 ± 0.04. Dilute solution viscometry (DSV) gives the Mark–Houwink relationship at 30 °C as [η] = 0.017Mη 0.73. The expansion factors calculated from DSV and MALLS agree reasonably well (α = 1.45 ± 0.25). The values of a, χ, and α indicate that MMA is a good solvent for PLA. The Carreau–Yasuda viscosity and Andrade–Eyring temperature models enable a quantitative description of the specific viscosity, ηsp, as a function of the intrinsic viscosity normalized concentration, c[η]. The quantitative description provides a powerful and generally applicable approach to formulating resins useful for composite fabrication. A new environmentally superior resin system is used to fabricate a composite panel using vacuum-assisted resin transfer molding.

Infusible liquid resins that polymerize into a thermoplastic are desirable for many applications. Similar to unsaturated and vinylester thermosetting systems, they consist of polymers dissolved in reactive monomer. This work presents a method to decrease cycle time by tuning the molecular weight and concentration of the predissolved polymer in the resin. Variation of these properties allows precise control of the viscosity which in turn controls the time at which peak exotherm is reached, the maximum temperature for a given part thickness, and cure time. Predictive models for the viscosity dependence on molecular weight, polymer concentration, shear rate, and temperature are developed. Two fiberglass panels are fabricated and tested; one with a lower molecular weight (Mw~30 kg mol−1) poly(methyl methacrylate) dissolved in methyl methacrylate and the second with higher molecular weight (Mw~500 kg mol−1) predissolved polymer in the resin. Mechanical properties are indistinguishable but the lower molecular weight panel cures up to three times faster. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48006.

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