Tailoring the Hydroxyl Density of Glass Surface for Anionic Ring-Opening Polymerization of Polyamide 6 to Manufacture Thermoplastic Composites

Abstract

Reactive thermoplastics matrices offer ease of processing using well-known molding techniques (such as Resin Transfer Molding) due to their initially low viscosity. For Polyamide 6 (PA6)/glass composites, the hydroxyl groups on the glass surface slow down the anionic ring-opening polymerization (AROP) reaction, and can ultimately inhibit it. This work aims to thoroughly control the hydroxyl groups and the surface chemistry of glass particulates to facilitate in situ AROP-an aspect that has been barely explored until now. A model system composed of a PA6 matrix synthesized by AROP is reinforced with calcinated and silanized glass microparticles. We systematically quantify, by TGA and FTIR, the complete particle surface modification sequence, from the dehydration, dehydroxylation and rehydroxylation processes, to the silanization step. Finally, the impact of the particle surface chemistry on the polymerization and crystallization of the PA6/glass composites was quantified by DSC. The results confirm that a careful balance is required between the dehydroxylation process, the simultaneous rehydroxylation and silane grafting, and the residual hydroxyl groups, in order to maintain fast polymerization and crystallization kinetics and to prevent reaction inhibition. Specifically, a hydroxyl concentration above 0.2 mmol OH·g−1 leads to a slowdown of the PA6 polymerization reaction. This reaction can be completely inhibited when the hydroxyl concentration reaches 0.77 mmol OH·g−1 as in the case of fully rehydroxylated particles or pristine raw particles. Furthermore, both the rehydroxylation and silanization processes can be realized simultaneously without any negative impact on the polymerization. This can be achieved with a silanization time of 2 h under the treatment conditions of the study. In this case, the silane agent gradually replaces the regenerated hydroxyls. This work provides a roadmap for the preparation of reinforced reactive thermoplastic materials.

Significant enhancement of mechanical properties for glass fiber fabric‐reinforced polyamide 6 composites by improving interfacial bonding

“…[7][8][9][10] However, most fiber surfaces have fewer surface active functional groups. [11][12][13][14] Therefore, various modification techniques were adopted to enhance the interfacial bonding between the polymer matrix and fibers. These technologies include chemical modification methods such as coupling and grafting, [15][16][17][18][19] surface irradiation methods, [20][21][22][23][24] incorporation of nanomaterials, [25][26][27][28][29] and plasma treatment.…”

“…The main focus of fiber‐reinforced composites is to achieve good interfacial bonding, as it plays a crucial role in determining the mechanical properties of composite materials 7–10 . However, most fiber surfaces have fewer surface active functional groups 11–14 . Therefore, various modification techniques were adopted to enhance the interfacial bonding between the polymer matrix and fibers.…”

Structure–Property Performance of Irradiated Sponge Rubber Blend Nanocomposites Containing h‐BN, GO, V2O5, and Adhesion on Cotton Fabric for Positive Electrode in Flexible Supercapacitors

“…The addition of BN or GO or V 2 O 5 to sponge NR and EPDM on cotton shows enhanced mechanical, thermal, and electrical properties of the final product by adding the silane agent ascribed to adhesion between the nanofiber and rubber interface leading to the hydrogen bonds formation between the nanofillers‐the silane‐the rubber matrix. [ 15 ] However, there is no report on the potential application of N or GO or V 2 O 5 to sponge NR and EPDM nanocomposite as electrodes in energy storage devices. Studies have been limited to the thermal, mechanical, and electrical enhancements of BN or GO or V 2 O 5 to sponge NR and EPDM nanocomposite.…”