Modification of graphene with silica nanoparticles for use in hybrid network formation from epoxy, novolac, and epoxidized novolac resins by sol-gel method: Investigation of thermal properties

Polystyrene‐modified novolac epoxy resin/clay nanocomposite: Synthesis, and characterization

“…This degradation step (290 to 440°C, 43 wt.%) is related to methylene bridges decomposition into methyl, phenol, and cresol groups. Degradation of phenol units are observed in the next stage . The residue at 600°C for this sample is about 36 wt.%.…”

“…The FTIR and 1 H NMR spectroscopies were employed for the characterization of the synthesized ENR as illustrated in Figures and . The FTIR spectrum of the NR exhibited the stretching vibrations of aliphatic and aromatic CH at 3020 to 2850 cm −1 region, the bending vibrations of CH at 1442 and 1351 cm −1 , the stretching vibrations of aromatic carbon‐carbon double band at 1602 and 1503 cm −1 , the stretching vibration of CO at 1226 cm −1 , the characteristic of ortho ‐ and para ‐substituted phenolic groups at 823 and 762 cm −1 , and the broad and strong band at about 3400 cm −1 is related to the stretching vibration of hydroxyl group …”

“…However, the curing of novolacs using HMTA generate volatile by‐products such as formaldehyde and ammonia, which resulted to voids in the networks. Therefore, HMTA‐cured novolacs are generally brittle in nature and have low fracture energies and impact strengths because of the voids combined and high crosslinking density, which limited their application ranges . In recent years, there have been many research efforts devoted to the design of new processes approaches or modification strategies toward the novolacs with enhanced physicochemical features in order to expand their application ranges .…”

“…[1][2][3][4] Novolacs are useful in a wide range of industrial applications including, coatings, molded pieces and articles, composite matrices, foam material, and electronic industries mainly because of their superior features such as good chemical and corrosion resistance, excellent hardness, solvent and moisture resistances, excellent thermal behavior (eg, heat resistance, low flammability, and slow heat release), and extremely low generation of toxic gases that stimulate their contribution to further market growth. [5][6][7] In general, hexamethylenetetraamine (HMTA) is the most widely used curing agent, along with heating to produce highly crosslinked novolacs. However, the curing of novolacs using HMTA generate volatile by-products such as formaldehyde and ammonia, which resulted to voids in the networks.…”

Preparation of Furfuryl Alcohol‐Functionalized Carbon Nanotube and Epoxidized Novolac Resin Composites with High Char Yield

“…It seems that incorporation of CNT or graphene into the curing reaction of phenolic resin can result in their better dispersion and therefore higher thermal properties. In the case of epoxidized novolac resin (ENR), modified graphene with silica nanoparticles were used for hybrid composite formation using sol‐gel method . However, incorporation of CNT or graphene into the matrix of ENR can be achieved by modification of CNT or graphene without using sol‐gel method and incorporation of silica/siloxane networks into the final thermoset product.…”