The rising concern towards the reduction in the use of petroleum-based, non-renewable resources and the need for more versatile polymer-based composite materials have led to increasing interests on natural polymer composites filled with natural organic fillers, i.e. coming from renewable and biodegradable sources. This paper reviews wood flour and other lignocellulosic fibres filled rubber composites, including cellulosic rubber composites, cellulosic thermoplastic elastomers, nanocellulose based rubber nanocomposites, with the aims at providing the most state of the art information for directing further scientific research, possible commercialization and design of cellulosic rubber composites. It has been found that 1) the surface properties of natural cellulose, hence the compatibility and interface of the natural cellulose and matrix rubber/plastics, are crucial for the successful development of the composites, such, physical and chemical modification and additives have been widely attempted to improve the incompatibility and poor interfacial adhesion between the filler and matrix; 2) the curing characteristics, mechanical properties, thermal stability and morphologies of the composites are complex but closely related to not only the interfacial properties, but also the compositions (e.g. the concentration of cellulosic materials) and other processing parameters; 3) the nature of hydrophilic cellulosic and hydrophobic matrix rubber and/or plastics requires an accurate introduction of coupling agent, one end of its structure shall be compatible to hydrophilic and the other to hydrophobic. The reviews on the main paths and results of study on the advanced nanocellulose reinforced rubber nanocomposites and sandwiches indicate much potentials and needs for further in-depth studies.

Lignocellulosic fibre mediated rubber composites: An overview

This review paper aims at reporting some of the notable works carried out concerning the use of nanoparticles (NPs) as a means of improving the resistance of fiber-reinforced polymer composite materials (FRPs) and adhesively bonded joints (ABJs) to delamination initiation and propagation. Applications of various nanoparticles, such as carbon-based, ceramic-based and mineral-based are discussed. The main properties that have been considered for improving the delamination and fatigue resistance of FRPs are the interlaminar shear strength, fracture toughness, and fracture energy. On the other hand, cohesive and interfacial strengths have been the focused parameters in the works that considered enhancement of ABJs. The reported results indicate that inclusion of NPs in polymeric matrices leads to improvement of various material properties, even though some discrepancies in the results have been noted. Notwithstanding, additional research is required to address some of the issues that have not yet been tackled, some of which will be identified throughout this review article.

Use of Nanoparticles for Enhancing the Interlaminar Properties of Fiber-Reinforced Composites and Adhesively Bonded Joints-A Review.

The use of fiber reinforced polymer (FRP) composites for the rehabilitation of buildings or other infrastructure is increasingly becoming an effective and popular solution, being able to overcome some of the drawbacks experienced with traditional interventions and/or traditional materials. The knowledge of long-term performance and of durability behavior of FRP, in terms of their degradation/aging causes and mechanisms taking place in common as well as in harsh environmental conditions, still represents a critical issue for a safe and advantageous implementation of such advanced materials. The research of new and better performing materials in such fields is somewhat limited by practical and economical constrains and, as a matter of fact, is confined to an academic argument.

https://www.mdpi.com/2073-4360/10/3/247/pdf

Durability Issues and Challenges for Material Advancements in FRP Employed in the Construction Industry.

Epoxy (EP) modified with nonpolar rubbers have the potential to achieve a concurrent improvement in mechanical and dielectric properties, when the EP-rubber interface is properly manipulated. Here we investigate rubber toughened EP based on a non-polar hydroxyl terminated polybutadiene (HTPB), and a coupling agent, dimer fatty acid diisocyanate (DDI), in which the rubber is covalently bonded to the epoxy. The mechanical and dielectric properties can be improved with the addition of HTPB and are maximized at 15 phr of elastomer inclusion. The enhanced mechanical toughness is attributed to the extensive shear yielding induced by a large amount of uniformly dispersed rubber particles; the same morphology can also combine the good insulating properties of HTPB and dielectrically favorable interfaces. These facts along with the reduced dielectric constant and loss for the modified EP suggest that the HTPB-DDI-EP can be used as a promising insulating packaging material for microelectronic applications.

Enhanced mechanical and dielectric properties of an epoxy resin modified with hydroxyl-terminated polybutadiene

Hybrid and hierarchical nanoreinforced polymer composites: Computational modelling of structure-properties relationships

Enhanced Fatigue Behavior of a Glass Fiber Reinforced Hybrid Particles Modified Epoxy Nanocomposite under WISPERX Spectrum Load Sequence

Fatigue life of a carbon fiber composite T-joint under a standard fighter aircraft spectrum load sequence

A thermosetting epoxy polymer was hybrid-modified by the addition of 9 wt.% of rubber microparticles and 10 wt.% of
silica nanoparticles. The GFRP composite laminates employing the unmodified epoxy matrix (GFRP-neat), and the hybrid epoxy matrix (GFRP-hybrid), were produced by a resin-infusion technique. The experimental fatigue lives of both GFRP composites under three different variable-amplitude load sequences, namely (a) a three-step increasing block (IB), (b) a three-step decreasing block (DB), and (c) a random block (RB) load sequence derived from a three-step load block, were determined. The fatigue life of the GFRP-hybrid composite was higher than that of the GFRP-neat composite under all
the three load sequence blocks investigated, by about�2.6 to�4.0 times. The matrix crack density and the stiffness
reduction rate were both lower in the GFRP-hybrid composite compared to the GFRP-neat composite material. The
suppressed matrix cracking and reduced delamination growth rates in the hybrid-modified epoxy matrix enhanced the
fatigue life of the corresponding GFRP-hybrid composite. Using the constant-amplitude fatigue data generated at various stress ratios, the fatigue lives under these variable-amplitude load sequence blocks were predicted using empirical models. The predicted fatigue lives, although conservative, were in reasonably good agreement with the experimental results.

Improved variable-amplitude fatigue behavior of a glass-fiber-reinforced hybrid-toughened epoxy composite

A thermosetting epoxy polymer was hybrid-modified by incorporating 9 wt.% of CTBN rubber micro particles and 10 wt.% of silica nano-particles. The unmodified and the hybrid-modified resins were poured into steel moulds and cured to produce bulk epoxy polymer sheets from which standard compact tension test specimens were machined. Fatigue crack growth tests were conducted using a 50 kN servo-hydraulic test machine, with the following test parameters: stress ratio, R = σmin/σmax = 0.1, sinusoidal waveform and frequency, ν = 3 Hz. The crack length was monitored by a compliance technique. The fracture surfaces were observed in a high resolution scanning electron microscope. The fatigue crack growth rate of the hybrid epoxy polymer was observed to be significantly lower than that of the unmodified epoxy polymer. The threshold stress intensity factor range, ΔKth, of the epoxy polymer was observed to increase by the addition of micron-rubber and nano-silica particles. The energy dissipating mechanisms viz, (i) cavitation of the rubber microparticles followed by plastic-deformation and void growth of the epoxy and, (ii) silica nanoparticle debonding followed by plastic-deformation and void growth of the epoxy, were observed to be operative and contribute for the reduced crack growth rate in the hybrid epoxy polymer.

/pdf/the-effect-of-micron-rubber-and-nano-silica-particles-on-the-12wmttrsec.pdf

The effect of micron-rubber and nano-silica particles on the fatigue crack growth behavior of an epoxy polymer

Carbon fiber composite laminate containing symmetric internal ply-drop simulating thickness variation was fabricated and tested to determine fatigue life under a standard mini-FALSTAFF spectrum load sequence. The fatigue life of ply-drop composite was significantly lower than that of plain composite due mainly to initiation and growth of delamination near the ply-drop location. The spectrum fatigue life was also predicted by empirical method. For this purpose, static and constant amplitude fatigue data was generated to construct constant life diagrams (CLDs). The spectrum fatigue life predicted using CLDs was in good agreement with experimental results for both plain and ply-drop composites.

N. Jagannathan

Papers

Enhanced Fatigue Behavior of a Glass Fiber Reinforced Hybrid Particles Modified Epoxy Nanocomposite under WISPERX Spectrum Load Sequence

Fatigue life of a carbon fiber composite T-joint under a standard fighter aircraft spectrum load sequence

Improved variable-amplitude fatigue behavior of a glass-fiber-reinforced hybrid-toughened epoxy composite

The effect of micron-rubber and nano-silica particles on the fatigue crack growth behavior of an epoxy polymer

Effect of ply-drop on fatigue life of a carbon fiber composite under a fighter aircraft spectrum load sequence