Thermosetting polymers have been widely used in many industrial applications as adhesives, coatings and laminated materials, among others. Recently, bisphenol A (BPA) has been banned as raw material for polymeric products, due to its harmful impact on human health. On the other hand, the use of aromatic amines as curing agents confers excellent thermal, mechanical and flame retardant properties to the final product, although they are toxic and subject to governmental restrictions. In this context, sugar-derived diepoxy monomers and anhydrides represent a sustainable greener alternative to BPA and aromatic amines. Herein, we report an "in-situ" sol-gel synthesis, using as precursors tetraethylorthosilicate (TEOS) and aminopropyl triethoxysilane (APTS) to obtain bio-based epoxy/silica composites; in a first step, the APTS was left to react with 2,5-bis[(oxyran-2-ylmethoxy)methyl]furan (BOMF) or diglycidyl ether of bisphenol A (DGEBA)monomers, and silica particles were generated in the epoxy in a second step; both systems were cured with methyl nadic anhydride (MNA). Morphological investigation of the composites through transmission electron microscopy (TEM) demonstrated that the hybrid strategy allows a very fine distribution of silica nanoparticles (at nanometric level) to be achieved within a hybrid network structure for both the diepoxy monomers. Concerning the fire behavior, as assessed in vertical flame spread tests, the use of anhydride curing agent prevented melt dripping phenomena and provided high char-forming character to the bio-based epoxy systems and their phenyl analog. In addition, forced combustion tests showed that the use of anhydride hardener instead of aliphatic polyamine results in a remarkable decrease of heat release rate. An overall decrease of the smoke parameters, which is highly desirable in a context of greater fire safety was observed in the case of BOMF/MNA system. The experimental results suggest that the effect of silica nanoparticles on fire behavior appears to be related to their dispersion degree.

Thermal and Fire Behavior of a Bio-Based Epoxy/Silica Hybrid Cured with Methyl Nadic Anhydride.

1.

We synthesized the esters of some peroxydicarboxylic acids\({\text{CH}}_{\text{3}} {\text{OOC(CH}}_{\text{2}} {\text{)}}_n \mathop {\text{C}}\limits^{\mathop {{\text{||}}}\limits^{\text{O}} } {\text{OO}}\mathop {\text{C}}\limits^{\mathop {{\text{||}}}\limits^{\text{O}} } {\text{(CH}}_{\text{2}} {\text{)}}_n {\text{COOCH}}_{\text{3}} \), and determined the kinetic parameters of the reaction for their thermal decomposition in CH3COOH and benzene. The predominant generation of CH3OOC(CH2). n radicals occurs in the decomposition of the lower homologs (n=2,3), while the\({\text{CH}}_{\text{3}} {\text{OOC(CH}}_{\text{2}} {\text{)}}_n \mathop {\text{C}}\limits^{\mathop {{\text{||}}}\limits^{\text{O}} } {\text{O}}\) radicals are obtained mainly from the higher homologs (n=6,8).




2.

A new homolytic cyclization reaction was discovered, namely the formation ofγ-butyrolactone from theγ-carbomethoxypropyl radicals that are obtained during the decomposition of the dimethyl ester of peroxydiglutaric acid.

Thermal decomposition of esters of peroxydicarboxylic acids

1

The 1,2,4-butane- and 1,2,5-pentanetricarboxylic acids were obtained via the addition of theβ-carboxyethyl andγ-carboxypropyl radicals to maleic acid




2

Some g10 and C14 unsaturated dicarboxylic acids were synthesized by the addition ofβ-carboxyethyl radicals to butadiene The relation between the yield of the products and the ratio of the reactants was determined

Addition of ω-Carboxyalkyl radicals to olefins, synthesis of DI- and trigarboxylic acids

A study was made of the effect of the salts FeSO4, MnSO4, and CoSO4 on the decomposition of peroxydisuccinic acid in aqueous medium. Both the composition and the yield of the reaction products are determined to a large degree by the nature of the metal ion.

Reaction of peroxydisuccinic acid with salts of metals of variable valence

https://link.springer.com/content/pdf/10.1007/BF00860055.pdf

Cyclization reaction of γ-carbomethoxypropyl radical toγ-butyrolactone

1.

New cyclic peroxydiacids were synthesized: peroxydi-cis-hexahydrophthalic, peroxydi-cis-Δ4-tetrahydrophthalic, and peroxydi-cis-endomethylene-Δ4-tetrahydrophthalic.




2.

The thermal decomposition of peroxydiacids in acetic acid obeys a first-order equation with respect to the peroxide. As a result of the decomposition of the peroxydiacids, anhydrides are formed. A mechanism was proposed for their formation by cyclization of acyloxy radicals.

B. A. Golovin

Papers

Thermal decomposition of esters of peroxydicarboxylic acids

Addition of ω-Carboxyalkyl radicals to olefins, synthesis of DI- and trigarboxylic acids

Reaction of peroxydisuccinic acid with salts of metals of variable valence

Cyclization reaction of γ-carbomethoxypropyl radical toγ-butyrolactone

Thermal decomposition of cyclic peroxydiacids