Preparation of alginate flame retardant containing P and Si and its flame retardancy in epoxy resin

Abstract

In the present paper, a novel biomass flame retardant based on alginic acid was synthesized through chemical combination with a reactive P-Si compound. Compared with alginates, the modified alginate showed obviously increased thermal stability and water resisting property, as well as better compatibility with epoxy resin, which can satisfy the requirements of a flame-retardant additive in the polymer. The flame-retardant properties were evaluated by vertical burning tests, limiting oxygen index, and microscale combustion calorimetry. Due to the self-charring capacity of alginate combined with the charring catalyst from P and the charring reinforcer from Si, the modified alginate exhibited much better flame retardancy, taking advantage of the formation of a more continuous, denser, and strengthened char layer than either individual alginate or P-Si flame retardant. The corresponding flameretardant mechanisms were investigated and discussed.

Molecular Dynamics Simulation and Experimental Studies on the Thermomechanical Properties of Epoxy Resin with Different Anhydride Curing Agents

“…The commonly accepted epoxy-anhydride reaction mechanism suggests that the reaction is an alternate ring-opening polymerization of anhydrides and epoxies [26]. Researches have shown that at high temperatures, in the presence of catalysts or with an excess of epoxy, homopolymerization of epoxy groups also occurs [19,27,28].…”

“…The curing reaction mechanism of epoxy-anhydride is shown in Figure 1. Without an accelerating agent, the main reactions between anhydride and epoxy resin were as follows: (1) micro-water opened the epoxy group to form a hydroxyl group, (2) hydroxyl and anhydride group produced monoester, (3) carboxyl and epoxy group formed diesters and (4) etherification of hydroxyl and epoxy groups was conducted [5,26]. Though the above main reactions, the epoxy resin 3D crosslinked network was finally formed.…”

Simple and green synthesis of calcium alginate/hydroxyapatite hybrid material without high temperature treatment and its flame retardancy

“…The synergistic effect between natural biomacromolecules and inorganic compounds has been a hot research direction for scientists recently. Compared with the complex and even harmful doping process of organics (Sun et al 2021b), inorganics doping is simpler and more environmentally friendly (Chen et al 2017). In our previous works, the ame retardant properties of CaAlg doped with inorganic substances such as calcium borate (Liu et Hydroxyapatite (Ca 10 (OH) 2 (PO 4 ) 6 , HAP), as an inorganic phosphate, may be effectively improve the ame retardancy of alginate for it possesses a very high decomposition temperature (above 1000 ℃) (Yang et al 2018).…”

Synthesis of a bio‐based piperazine phytate flame retardant for epoxy resin with improved flame retardancy and smoke suppression

“…On the basis of the reported studies, most bio‐sourced materials are a category of organic compounds with carbon backbone, for example algal acid, cyclodextrin, chitosan, lignin, dopamine, 19–23 etc., which are usually applied as carbon sources in some intumescent flame retardant systems. For example, Chen et al 24 synthesized an algal acid‐based P‐Si containing flame retardant from calcium alginate (CA) and γ‐(2,3‐epoxypropoxy) propytrimethosysilane (DPP), called CADPP for EP, and results exhibited that sample EP/30 wt% CADPP passed a V0 rate in UL‐94 standard tests with a LOI raising to 29.3%, and the total heat release was lowered by 31.6% than that of pure EP. In another study, Chen et al 25 reported synthesis of a flame retardant from chitosan, cinnamaldehyde and DOPO (namely CCD), and found that the EP composite with 10 wt% CCD reached a LOI of 31.6% with V0 UL‐94 rate.…”