Bio-Based Flame-Retardant Epoxy Resins

Bio-Based Flame-Retardant Epoxy Resins The non-renewable nature of petroleum and petroleum-derived resources, their environmental harm and limited availability have recently increased interest in polymer material production from renewable natural sources. Flame retardants are largely toxic to both the environment and humans, causing endocrine disruption, infertility, cancer, neurobehavioural problems, and embryotoxic and teratogenic effects. Inhalation of toxic volatile products generated during fires (e.g. carbon monoxide, hydrogen cyanide, hydrocarbons, dioxins, acrolein, formaldehyde, etc.) can be fatal. Until recently, organophosphorus compound-based flame retardants were considered safe, but recent research has found them to be persistent in the atmosphere, soil, water and biological samples. Bio-based flame retardant additives can be applied by mixing with the base material through physical methods. This method does not affect the material manufacturing process and is easy and inexpensive to apply. For this reason, it is frequently preferred in industrial applications. Inorganic flame retardant additives are frequently preferred for reasons such as low cost, low toxicity, low wear and low smoke generation. Metal hydroxides and metal hydroxycarbonatss are among the most important inorganic flame retardants, constituting approximately 50% of flame retardants worldwide. Phytic acid, a naturally occurring compound, is considered a green macromolecule and one of the main storage forms of phosphorus-containing compounds; it is abundant in plant tissues such as soybeans, grain kernels and oilseeds. Phytic acid (PA) is a plant-derived and phosphorus-rich compound for protecting polymeric materials against flame. PA also contains functional hydroxyl and phosphate groups, exhibiting attractive feasibility and functionality when applied to different types of materials. Epoxy resin refers to a type of reactive prepolymer and polymer containing epoxide groups. These resins react either with themselves in the presence of catalysts or with numerous auxiliary reactants such as amines, phenols, thiols, etc. Epoxy resin has many industrial applications for various purposes. It has higher mechanical properties compared to other resin types and greater thermal and chemical resistance. For this reason, it has special use in the manufacture of aircraft components [1]. Another way to effectively improve the flame retardancy of epoxy resin is to reinforce it with nano-sized inorganic particles. Using this approach, improvements in flame retardancy and the preservation or enhancement of mechanical properties is effective even at relatively low filler content. BADGE is frequently used in epoxy resin manufacturing. However, BADGE is known as an endocrine-disrupting chemical (EDC) due to its oestrogenic properties. For these reasons, interest in bio-based epoxy resins has increased. Vegetable oils are an important bio-renewable resource for bio-based polymers due to their availability and competitively low price [2]. Cardanol and cardanol derivatives extracted from cashew nut shell liquid (CNSL), a new by-product in industry, are produced in large quantities and are used particularly in the coatings sector due to their harmlessness to the environment and human health [3]. Sol-gel processing is a common method used in obtaining organic/inorganic, nanocomposite or hybrid thin films. Bio-based epoxy resin synthesis is being successfully carried out at İzel Kimya R&D Centre. Project work is ongoing on bio-based epoxy resins utilizing the flame-retardant properties of phytic acid. References 1. Bray, PG., (1999) Epoxy Resins. Europe PMC, 14, 743-758. 2. Kathalewar, M., and Sabnis, A., (2014) Epoxy resin from cardanol as partial replacement of bisphenol-A based Epoxy for coating application. Journal of Coatings Technology and Research, 11, 601-618. 3. Wazarkar, K., and Sabnis, A., (2018) Cardanol based anhydride curing agent for Epoxy coatings. Progress in Organic Coatings, 118, 9-21.   Dr. Cemil Dizman - R&D Manager İzel Kimya Semiha Eral - R&D Researcher İzel Kimya