Addition‐curable propargyl‐containing novolac‐type phenolic resin: Its synthesis, characterization, cure, and thermal properties

Abstract

ABSTRACT:In this article, propargyl functionalized novolac resins (PN resins), with varying propargyl contents and varying molecular weights, were synthesized conveniently. The structural characteristics were determined by 1 HNMR and FTIR methods. Thermal cure studies revealed that the uncatalyzed thermal cure was remarkably affected by propargyl extent, while it was hardly affected by molecular weight. The processability of the as-prepared PN resins was excellent as matrix of composite materials. The cure mechanism was complicated; postcure at high temperature was required to achieve entire crosslink formation. Both dynamic mechanical analysis and thermogravimetric analysis showed that the cured PN resins had substantially improved thermal mechanical properties and thermal stability in comparison to conventional cured phenolics. High propargyl extent was preferred for high thermal stability. The results show that PN resin is one of the ideal candidates for advanced composites matrices in thermostructural and ablative applications.

Propargylated novolac resins for fibre‐reinforced plastics: Processing aspects

“…This result is in close accordance with the results of the Reghunadhan Nair study where the maximum etherification achieved was 82 %. While using alcohols as reaction media, KOH as a base, and phenolic resins with low molecular masses (< 1000 g/mol), a high etherification degree (close to 100 %) could be achieved …”

Syntactic Foams

“…In the last decade, PN resins and their blends have been explored as candidate matrices for advanced composites in thermostructural and thermal shielding applications [23,26,27]. Similar addition-curable phenolic resins functionalized with respect to groups such as allyl groups [28], phenyl maleimide [29], acetylene [24], phenyl ethynyl [18], etc., have been reported. Figure 13.3 Synthesis and curing of PN resin [25].…”

Ethynyl aromatic siliconhybridized resin: Synthesis, characterizations, and thermal properties

“…For example, phenolic resins are considered to have several desirable characteristics, such as thermal resistance, flame retardance, and superior ablative properties. However, the shortcomings originating from their brittle structure and volatile emitting cure mechanism dispel their application as a high temperature resin for advanced engineering materials 2. Polyimides have been extensively used as structural or substructural materials in aeronautic and astronautic industry for their good thermal and dimensional stability, but they are still limited due to difficulties in processability and solubility in common organic solvents 3.…”