Epoxy–Amine Based Nanocomposites Reinforced by Silica Nanoparticles. Relationships between Morphologic Aspects, Cure Kinetics, and Thermal Properties

In general, the incorporation of nanoparticles into polymers shows an increase of the materials performances, but the effect of the nanosized objects is still not well understood. In this study, we have investigated the impact of incorporation of silica nanoparticles in an epoxy/amine (DGEBA/<i>m</i>PDA) system. Naked silica nanoparticles (SiNP) were synthesized via a sol–gel technique. To evaluate the interfacial effect on properties of nanocomposites, the surface of the nanoparticles was modified by substituting silanol groups into epoxide functions (SiNPEp). A new method was elaborated for obtaining different organic–inorganic nanocomposites with a very good dispersion without any aggregation according to transmission electron microscopy (TEM) analyses. The influence of the different silica nanoparticles (SiNP or SiNPEp) on the mechanisms of the reaction between epoxy and amine groups is highlighted. Important new inputs on the cure kinetics of the epoxy/amine mixture are given. The glass transition temperatures and thermal properties of nanocomposites have been examined, and relationships have been established

Effects of Incorporation of Organically Modified Montmorillonite on the Reaction Mechanism of Epoxy/Amine Cure

The aim of this study is to understand the effect of nonmodified or different organically modified montmorillonites on the reaction mechanism of epoxy/amine cure. The reference material consists of diglycidyl ether of bisphenol A (DGEBA) and 1,3-phenylene diamine (<i>m</i>PDA) in stoichiometric proportions. The reaction with various organically modified montmorillonites (I28E, I34TCN, and MMTm) is compared to highlight the catalytic effect of MMT water content and of the alkylammonium cations on the epoxy/amine reaction mechanism. In the absence of <i>m</i>PDA curing agent, DGEBA develops homopolymerization reactions with I28E, I34TCN, and MMTm. Chemorheological kinetics and advanced isoconversional analysis of epoxy cure are studied by rheometrical measurements and differential scanning calorimetry (DSC). Molecular mobility of the system under curing is modified in the presence of montmorillonites. Finally, the study underlines the role of montmorillonites and the influence of the change in reaction mechanisms on glass transition of the nanocomposites

Recyclable, Repairable, and Fire-Resistant High-Performance Carbon Fiber Biobased Epoxy

Due to the global environmental concerns caused by the ever-increasing environmental impact, landfill materials, and CO2 emission, there is a critical need in the elaboration of sustainable composite materials. Advanced material composites used in the production of high-performance products to solve some of the most difficult engineering challenges are having a key role in decarbonization by their light weight, higher performance, and increasing durability. In this work, sustainable carbon fiber reinforced composites (CFRCs) have been engineered with an environmentally friendly epoxy resin derived from natural and renewable compounds employing an industrial feasible manufacturing protocol. The thermosetting resin with a biobased organic carbon content (BOC) of ∼77% was synthesized by combining a renewable based monomer, the triglycidyl ether of phloroglucinol (TGPh), with hexahydro-4-methylphthalic anhydride (HMPA). The developed CFRCs show high performance with high glass transitions Tg > 350 °C, a high storage modulus ∼42 GPa, a high interlaminar shear strength ∼63 MPa, and a compressive strength ∼400 MPa. In addition, the outgassing tests show that both the resin and the CFRCs are compliant for space application. Moreover, the biobased CFRCs exhibit chemical recyclability, reprocessability, and excellent intrinsic flame resistance

Valorization of Biorefinery Side-Stream Products: Combination of Humins with Polyfurfuryl Alcohol for Composite Elaboration

A challenge of today’s industry is to transform low-value side products into more value-added materials. Humins, a byproduct derived from sugar conversion processes, can be transformed into high value-added products. Thermosetting furanic composites were elaborated with cellulose filters. Large quantities of humins were included into a polyfuranic thermosetting network. Comparisons were made with composites generated with polyfurfuryl alcohol (PFA) and with PFA/lignin. It was concluded that new chemical interactions were created between the side-chain oxygen groups of the humins and the PFA network. Analysis of the fracture surface of the composites containing humins lead to the conclusion that higher interfacial bonding and more efficient stress transfer between the matrix and the fibers is present. The higher ductility of the humins-based matrix allows for a two-fold higher tensile strength in comparison with other composites tested. Incorporation of humins decreases the brittleness of the furanic composites, which is one major drawback of the pure PFA composites