Low Heat Release Capacity Research Articles

Bisphenol-1,2,3-triazole (BPT) Epoxies and Cyanate Esters: Synthesis and Self-Catalyzed Curing

Novel bisphenol-1,2,3-triazole (BPT) resins, including epoxy (DGE-BPT) and cyanate ester (BPTCE) systems, were prepared and used in curing chemistry with no added reagents or catalysts. The materials were characterized relative to conventional epoxies and cyanate esters, in terms of curing and thermal properties, and the curing process and products were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), pyrolysis combustion flow calorimetry (PCFC), and small scale flame tests. These novel BPT-based resins cure in the absence of added catalysts and exhibit exceptionally low heat release and high char residue. Despite the absence of antiflammable additives (either halogenated or inorganic compounds), BPTCE itself was found to be nonignitable, with extremely high char residue value (67%) and extraordinarily low heat release capacity (HRC of ∼10 J/(g K)).

A renewable waste material for the synthesis of a novel non-halogenated flame retardant polymer

The recognition of toxicity and environmental persistence of halogenated flame retardant (FR) materials has prompted the reduction in their usage across the globe. There is an immediate need for new types of non-toxic and effective FR produced preferably through sustainable routes. Here we report the synthesis and characterization of a new polyphenolic FR material based on a renewable and biodegradable starting material, cardanol (a byproduct of cashew nut processing). Cardanol was polymerized in aqueous media using various types of oxidants. The thermal properties of the resulting polymers were investigated. Polycardanol synthesized using a specific type of oxidant exhibited good thermal stability and low heat release capacity. Preliminary results obtained from this study are quite promising and indicate the possibility of synthesizing new types of FR materials from bio-based phenols.

Halogen-free, low flammability polyurethanes derived from deoxybenzoin-based monomers

Two novel deoxybenzoin-containing monomers, a diisocyanate and a diol, were synthesized and used to prepare polyurethane materials and foams. 4,4′-Diaminodeoxybenzoin was prepared by Ullmann coupling of 4,4′-dibromobenzil with tert-butyl carbamate. Reduction of one of the carbonyl groups, and t-Boc deprotection, gave the aromatic diamine, which was converted to 4,4′-deoxybenzoin diisocyanate (DBDI) with triphosgene. DBDI was then used to prepare two different polyurethanes, one by reaction with 1,3-propanediol, and the other by reaction with deoxybenzoin diol. The polyurethanes obtained from these reactions displayed low heat release capacity (HRC) values relative to conventional polyurethanes prepared from 4,4′-methyldiphenyl diisocyanate (MDI) and 2,4-toluene diisocyanate (TDI). Polyurethanes prepared in this study displayed HRC values as low as ∼130 J g−1 K−1, and char yields as high as ∼40%. In addition, deoxybenzoin-based oligomers containing hydroxyl end groups were also synthesized and used to prepare polyurethane foams that displayed markedly lower HRC values, and higher char yields, than conventional polyurethane foams, which burn readily and drip. Taken together, the integration of deoxybenzoin moieties into the diisocyanate or polyol component of the polymer structure is found to lower heat release rates and reduce flammability in the absence of any added flame retardant, such as halogenated compounds that represent health and environmental hazards.

Poly(arylate‐phosphonate) copolymers with deoxybenzoin in the backbone: Synthesis, characterization, and thermal properties

AbstractDeoxybenzoin‐based copolymers containing various relative ratios of arylate and phosphonate units in the backbone were synthesized by solution polycondensation. These copolymers were characterized by gel permeation chromatography, Fourier Transform infrared spectrometry, and proton, carbon, and phosphorous nuclear magnetic resonance spectroscopy (1H, 13C, and 31P NMR). Pyrolysis combustion flow calorimetry (PCFC) performed on these copolymers revealed their very low heat release capacity, making them attractive for applications in which halogen‐free, low flammability materials are desired. Integration of phosphonate units into the polymer backbone is advantageous for achieving high molecular weight polymers with solution processbility while retaining the low flammability inherent to deoxybenzoin‐based polymers. Char yields greater than 50% and heat release capacities of 40–60 J/g K, were observed for these copolymers by PCFC. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4573–4580, 2007