Designed and tailor-made double hydrophilic block copolymer-graphene nanoplatelet hybrids for reinforcing epoxy thermosets

Because of their propensity to build micellar nanostructures, amphiphilic block copolymers (ABCs) are an appropriate and unique toughening agent for epoxy systems individually on their own and in grafted form. The presence of epoxiphilic and phobic ends in ABCs is responsible for the self-assembly and the micellar structure. Nanofiller-grafted ABCs can effectively enhance the toughness of epoxy via the synergistic interaction of nanofillers and the ABCs. Even though there is sound literature supporting the effect of ABCs in epoxy, the action of double hydrophilic block copolymers (DHBC) in the epoxy matrix is less handled. Hence, the grafting of nanofillers in DHBCs and their subsequent role in tuning the properties of epoxy is a new concept. Hence this paper tries to bridge the gap via studying the effect of grafted fillers based on DHBCs in epoxy matrix. As a result, the current study focuses on the synthesis of double hydrophilic graphene nanoplatelets (rGO-g-DHBC) via nitrogen oxide-mediated polymerization for epoxy toughening application. The prepared rGO-g-DHBC was effectively utilized for epoxy toughening applications, resulting in a 457% improvement in toughness without compromising its inherent tensile strength. The mechanism behind the improved toughness was elucidated with the help of a scanning electron microscope, and the thermal, and rheological characteristics were studied.

Nano-modified epoxy: the effect of GO-based complex structures on mechanical performance

The application of nanofillers (NFs) in multicomponent polymer systems is accompanied by important structure-directing effects that are more marked in partially miscible systems, such as polymer-modified epoxy. This study deals with rubber-modified epoxy using different combinations of GO and amine-terminated butadiene-acrylonitrile copolymer (ATBN), including in situ and pre-made grafting. Moreover, GO grafted via planar epoxy groups or solely edge-localized carboxyls was used. It is shown that the grafted ATBN chains promote the assembly of GO-g-ATBN into nacre-mimicking lamellar structures instead of usual exfoliation in thermoplastics. This complex structure of elastically embedded GO leads to the best mechanical performance. It is obvious that a small concentration of the grafted polymer exceeds the contribution of a higher concentration of separately added ATBN. The results highlight the important effect of the degree of grafted chains and geometry of the internal structure of the self-assembled arrays and their effect on the mechanical performance.

ATBN-grafted GO forms nacre-mimicking lamellar structures in epoxy; the effect of grafting geometry on the structure/property relationship is highlighted.

Synthesis of Benzene Tetracarboxamide Polyamine and Its Effect on Epoxy Resin Properties

Epoxy resins have found various industrial applications in high-performance thermosetting resins, high-performance composites, electronic-packaging materials, adhesives, protective coatings, etc., due to their outstanding performance, including high toughness, high-temperature performance, chemical and environmental resistance, versatile processability and adhesive properties. However, cured epoxy resins are very brittle, which limits their applications. In this work, we attempted to enhance the toughness of cured epoxy resins by introducing benzene tetracarboxamide polyamine (BTCP), synthesized from pyromellitic dianhydride (PMDA) and diamines in N-methyl-2-pyrrolidone (NMP) solvent. During this reaction, increased viscosity and formation of amic acid could be confirmed. The chemical reactions were monitored and evidenced using ¹H-NMR spectroscopy, FT-IR spectroscopy, water gel-phase chromatography (GPC) analysis, amine value determination and acid value determination. We also studied the effect of additives on thermomechanical properties using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamical mechanical analysis (DMA), thermomechanical analysis (TMA) and by measuring mechanical properties. The BTCP-containing epoxy resin exhibited high mechanical strength and adhesion strength proportional to the amount of BTCP. Furthermore, field-emission scanning electron microscopy images were obtained for examining the cross-sectional morphology changes of the epoxy resin specimens with varying amounts of BTCP.

Blocked isocyanate silane modified Al2O3/polyamide 6 thermally conductive and electrical insulation composites with outstanding mechanical properties

When the content of Al₂O₃ was higher than 50 wt%, the tensile strength of KH-331 modified Al₂O₃/PA6 composites decreased, but the tensile strength of MEKO blocked isocyanate-propyltriethoxy silane modified Al₂O₃/PA6 composites increased.

Effect of side-wall functionalisation of multi-walled carbon nanotubes on the thermo-mechanical properties of epoxy composites

Sidewall functionalisation of multi-walled carbon nanotubes using liquid rubber results in enhancement in thermo-mechanical properties of epoxy composites.

Toughening of an epoxy thermoset with poly[styrene-alt-(maleic acid)]-block-polystyrene-block-poly(n-butyl acrylate) reactive core–shell particles

Reactive core–shell particles for epoxy toughening were synthesized via reversible addition–fragmentation chain transfer emulsion polymerization mediated by an amphiphilic macro-RAFT agent followed by core-crosslinking to increase stability.

Effect of grafted amine groups on in-plane tensile properties and high temperature structural stability of borophene nanoribbons

The effects of grafted amine groups on in-plane tensile properties and structural stability of armchair and zigzag borophene nanoribbons (ABNRs and ZBNRs) are investigated by using molecular dynamics.