Biobased vinyl levulinate as styrene replacement for unsaturated polyester resins

Abstract

Vinyl levulinate (VL) is used as a biobased reactive diluent in styrene (St)-free unsaturated polyester resins (UPR). The reactivity ratios for the radical copolymerization of VL with diethyl fumarate (DEF) are determined by the Jaacks method (r VL 5 0.01 and r DEF 5 0.81 at 60 C in DMSO-d 6 ). The properties of UPRs having a stoichiometric ratio between unsaturated groups from the UPR and either St or VL are compared. Defect-free, slightly yellow, transparent, and rigid thermosets are obtained after a mild curing cycle. Due to unfavorable reactivity ratios about 5.5 wt % of unpolymerized VL remains inside the network and acts as plasticizer. Consequently, compared with St-based ones, VL-based UPRs exhibit lower a relaxation (T a 5 180 and 100 C, respectively), lower elastic moduli at the rubbery plateau (G 0 5 10 8 and 10 7 Pa) and lower mechanical properties as measured by three points bending tests. Strain at break (e f 5 1.8 6 0.2%) and Charpy impact strength (2.7 6 0.3 kJ m 22 ) are comparable independently of the RD chemical nature.

Toward replacement of styrene by bio-based methacrylates in unsaturated polyester resins

“…We recently reported on the use of vinyl levulinate (VL), derived from levulic acid that belongs to the TOP12 list of the most promising renewable building blocks, 21 , 22 as a RD for UPRs. 23 The reactivity ratios that were experimentally determined (with r F = 0.81 and r VL = 0.01) confirmed the previous statements: around 5.5 wt% of unpolymerized VL remained inside the prepared UPR network and acts as plasticizer. As illustrated by the two previous situations, it is of high importance that the RD readily reacts in the curing conditions (by copolymerization and/or homopolymerization) such that no residual remains in the obtained thermoset.…”

Replacement of styrene with acrylated epoxidized soybean oil in an unsaturated polyester resin from propylene glycol and maleic anhydride

“…However, the flexural strength of the styrene‐free resins was 20% to 50% lower than that of the styrene‐containing resins . Vinyl levulinate has also been studied as a styrene replacement in UPE resins . It was found that the flexural strength and flexural modulus of the cured styrene‐free resins were 35% lower than those of the styrene‐containing resins .…”

Syntheses of donor acceptor biobased photocurable water‐soluble resins based on poly‐l‐lysine

“…16 A new trend in the polymerization field is the use of radiation as a source of energy. For instance, this technique has been used for the formation of hydrogels, mainly with polysaccharides.…”