Rheological properties, cure characteristics, and morphology of acrylonitrile‐based nanorubber modified epoxy

Abstract

This article investigates the effects of nano carboxylic acrylonitrile butadiene rubber (CNBR-NP) and nano acrylonitrile butadiene rubber (NBR-NP) on the rheological properties and cure characteristics of epoxy. Dynamic mechanical behavior of carbon fiber reinforced polymer composites (CFRP) with the nanorubber-modified matrices was also studied. Rheological study showed that NBR-NP blends attained lower viscosity in comparison to CNBR-NP blends and both systems exhibited shear-thinning behavior. Scanning electron microscopy (SEM) images revealed that CNBR-NP could be dispersed evenly within the epoxy matrix using industrial mixing process whereas partial agglomeration was observed in NBR-NP blends. The dynamic mechanical analysis (DMA) data showed that the addition of nanorubber has negligible effect on the glass transition temperature of the epoxy. The difference in the dispersion ability of these two nanorubbers in epoxy is related to the difference in van der Waals forces between single nanoparticles, the chemical formula and the polarity of the systems.

Toughening of carbon fibre reinforced polymer composites with rubber nanoparticles for advanced industrial applications

“…The morphology and the change in stoichiometry of the matrix with the nanorubber dispersion can affect the interlaminar shear stiffness and strength properties. However, we have proved with dynamic mechanical analysis that the change in the degree of crosslinking with the nanorubber modification is insignificant [14]. To summarise, the consistent decrease of the APS value with the nanorubber concentration may be explained by the lower quality of the laminates with high void content, and by the low stiffness of the nanorubber particles that cause a reduction in the stiffness of the resin.…”

“…In our previous work, the effect of acrylonitrilebased nanorubbers on the cure kinetics, physical properties and the processing of epoxy resin were studied. We have showed that the acrylonitrile based nanorubber materials do not increase the viscosity of the specific epoxy resin beyond its processing limits; neither do they affect the T g of the system [14]. Hence, previous work deals with the properties of the nanorubber-toughened matrix resin only, and the current work represents a continuation, studying the mechanical properties of the CFRP composites with the nanorubber toughened epoxy resin matrices.…”

“…This is due to the carboxyl group of CNBR-NP, helping with better dispersion in the matrix [25]. Further details on the morphology of these blends can be found in [14]. The toughening mechanisms of both systems were identified as crack front pinning, crack path deflection, crack bridging and nano rubber debonding, the latter followed by plastic void growth of the epoxy (Figure 3).…”

“…The curing agent and the accelerator were added and the final mixture was speed-mixed at 2100 rpm for 6 minutes. Further details on the manufacturing techniques adopted can be found in [14]. A hand lay-up technique was used to produce the CFRP laminates.…”

“…In general, a significant improvement in the fracture toughness of the composites with the addition of nanorubber to their matrices is usually accompanied by a modification of the glass transition temperature (T g ) [16]. The work proposed in this paper is novel because it presents for the first time -to the best of the Authors' knowledge -a class of composites for which none of the intrinsic properties are deteriorated by the dispersion of nanorubber into their matrices [14]. The composites we present in this work feature a significant improvement in the delamination fracture toughness without any noticeable change in the T g .…”