Synthesis and Characterization of a Bio‐Based Resin from Linseed Oil

Abstract

Summary: The use of renewable raw materials in the polymer industries is becoming increasingly popular because of environmental concerns and the need to substitute fossil resources. Plant oils with triglyceride backbones can be chemically modified and used to synthesize polymers from renewable resources (biopolymers). In the present study, linseed oil was epoxidized using a chemo‐enzymatic method based on Candida Antarctica lipase B (CALB) as a biocatalyst and the modified linseed oil was cured using maleinated linseed oil and a commercial polyamide resin. The amount of epoxidation achieved depended on the amount of lipase used and was determined by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies. With 20% (weight per weight) catalyst concentration based on the wt % of oil a degree of epoxidation of > 90% was achieved. The cross‐linking reaction of epoxidized linseed oil with the maleinated linseed oil and the polyamide resin was studied using differential scanning calorimetry (DSC). DSC traces showed that an increase in epoxidation degree lead to larger values for the exothermic enthalpy integrals of the curing reactions and hence to a higher reactivity of the linseed oil towards the cross‐linking agents.

Development of toughened bio‐based epoxy with epoxidized linseed oil as reactive diluent and cured with bio‐renewable crosslinker

“…The disappearance of the olefinic proton (―CH═CH―) signals in the region between δ = 5.34 to 5.43 further confirmed the epoxidation. Similar spectra were noticed for synthesized ELO by Kim et al and Mahendran et al 13 C NMR spectra are provided in supplementary file (Figure S2) for further confirmation of epoxidation.…”

“…The characteristic C―O―C stretching band from the oxirane vibration appears within the range 820 to 843 cm −1 . The most significant signal at 825 cm −1 reveals the epoxy group of ELO as reported by Kim et al and Mahendran et al…”

“…Among the non‐edible oils, linseed oil is the most ideal candidate for such application because of its distinctive structure. Further, its high degree of unsaturation or reactive sites (6.6 double bonds per triglyceride chain) has attracted the researchers exploring bio‐based or sustainable polymers with higher performance . To achieve improved mechanical and thermal properties, the curing agent also plays an important role while it crosslinks the bio‐resins via polyaddition or copolymerization reactions to form rigid, dimensionally, and thermally stable networks.…”

Development of completely bio‐based epoxy networks derived from epoxidized linseed and castor oil cured with citric acid

“…However, there is a great demand of large‐scale usage of nonedible renewable resources by the industries to form resins and polymers. Linseed oil (LO) is the most ideal alternative to petroleum‐based resources on account of its unique composition (56% linolenic content) . Its high degree of unsaturation (6.6 double bonds per triglyceride) receives greater importance as a biorenewable raw material to form prepolymers or even polymers.…”

Selected biotrends in development of epoxy resins and their composites

“…The literature contains many studies focused on epoxidation conditions of different vegetable oils-e.g. soybean [26][27][28][29][30][31][32], linseed [33], rapeseed [34] [41,42] oil. Epoxidized soybean oil (ESO) is of a particular interest to researchers.…”