Reinforced Vinyl Ester Resin Composites Research Articles

Phosphorus-containing reactive compounds to prepare fire-resistant vinyl resin for composites: Effects of flame retardant structures on properties and mechanisms

The traditional flame-retardant method for carbon fiber reinforced vinyl ester resin composites is to add a large amount of solid flame retardants, which not only leads to the deterioration of the material's mechanical properties, but also increases the resin viscosity and affects the molding process of composites. In addressing this issue, this work adopts a liquid reactive flame retardant strategy and synthesizes six novel liquid phosphorus-containing reactive compounds as flame retardants. A comparative study is conducted on the effects of the structure of compounds (valence and group of phosphorus and number of reaction groups) on the properties of materials. The results demonstrate significantly improved flame retardancy and toughness, as well as unaffected viscosity and strength of the resin. When the phosphorus content does not exceed 3 wt%, the limiting oxygen index (LOI) of the resin can reach over 30% and UL-94 passes the V-0 rating. The structure of compounds significantly affects their flame retardancy mechanism. Especially, compounds rich in P-O-C structure have more outstanding condensed phase flame retardancy (promoting charring) and are more favorable for improving the LOI; Compounds rich in P-Ph and P-C structures have higher thermal stability and mainly exert gas phase flame retardancy, which is more beneficial for improving the self-extinguishing properties of materials. Furthermore, a synergistic flame retardant effect is observed between carbon fiber and compounds rich in P-Ph.

Mechanical properties of Nomex honeycombs filled with tubes of carbon fibre reinforced vinyl ester resin composites

The Nomex honeycomb structures filled with carbon fibre reinforced vinyl ester resin composite tubes (NHFCT) were proposed to improve the energy absorption capacity of Nomex honeycombs. Thereafter, the mechanical properties of the NHFCT structures were explored based on the quasi-static pressure test, finite element simulation, and a theoretical model. The test result showed that the NHFCT structures enable increased SEA while retaining the energy absorption performance of Nomex honeycombs. When applying a certain load on the NHFCT structures, the Nomex honeycombs are folded; the CFRP tubes are torn and expanded, and the embedded cells bulge. The established finite element simulation model was used to simulate the deformation of NHFCT structures and the theoretical model was employed to predict their energy absorption performance. Tests applicable to the practical application revealed that NHFCT structures of a large area present more stable performance and the superimposed NHFCT structures are subjected to step-wise gradient deformation. The CFRP tubes suffer slight indentation on the panel between layers and they are torn in a funnel shape under the effect of the panel stiffness. The research provides reference for improving the mechanical properties of Nomex honeycomb structures and broadening their range of application.

Enhancement of interface performance between shape memory alloy fiber and polymer matrix using silane coupling agent KH550 and Al2O3 nanoparticles

The interface performance of nickel‐titanium (Ni‐Ti) shape memory alloy (SMA) fiber reinforced vinyl ester resin composites was investigated in this work. All the SMA fibers were pre‐treated with H2SO4 and NaOH solution. The fiber surfaces were coated with Al2O3 nanoparticles and silane coupling agent KH550. For comparison, two groups of SMA fibers were coated only with the silane coupling agent or the nanoparticles. Furthermore, the effect of the nanoparticle content on the interface performance of the composites was investigated for Al2O3 nanoparticle contents ranging from 1 wt% to 4 wt%. Scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDX) were used to study the effect of the surface modifications. The results demonstrate that all the modified methods enhance the interface strength of the SMA/vinyl ester resin, but samples with SMA fibers coated with both the silane coupling agent and 3 wt% Al2O3 nanoparticles have the best interface performance. SEM observations show that the dispersion of nanoparticles increases when the silane coupling agent is added to the composites. POLYM. COMPOS., 39:3040–3047, 2018. © 2017 Society of Plastics Engineers

Improving the interfacial properties of carbon fibers/vinyl ester composites by vinyl functionalization on the carbon fiber surface

APMA functionalized CFs can significantly improve the interfacial adhesion properties of the carbon fiber reinforced vinyl ester resin composites.

PROCESSING AND CHARACTERIZATION OF GLASS FIBER AND CARBON FIBER REINFORCED VINYL ESTER BASED COMPOSITES

Composites materials are used in almost all aspects of the industrial and commercial fields in aircraft, ships, common vehicles, etc. Their most attractive properties are the high strength-to-weight ratio.Polymer composites are used because overall properties of the composites are superior to those of the individual polymers. The aim of this experimental study has targeted to investigate the mechanical strength of glass fiber & carbon fiber reinforced vinyl ester resin composites. The laminated specimens were fabricate using Hand lay-up technique. and the specimens are subjected to the investigated as per the ASTM standards. The tensile tests, compression tests, flexural tests were carried out on the laminated specimen for the determination of its mechanical properties.

The Mechanical Properties of Jute Fiber Mats Reinforced Vinyl Ester Resin Composites

Surfaces of jute fiber needled mats were treated by alkali, potassium permanganate and A-151 silane coupling respectively, and those reinforced vinyl resin composites were made by VARTM method . The changes of the surface energy of the jute fiber mats were analyzed basing on the dynamic contact angle, and the surface of the jute fiber and the interface morphology of the composites were observed by SEM. The results showed that interface compatibility and the comprehensive properties of the composites were improved evidently, because the surface energy of the jute fiber was lowered and the surface micro-structures of the fiber were changed. Especially, the tensile strength and flexural strength of the composites treated by A-151 silane coupling increased by 63.08% and 94.79% respectively.

Viscoelastic interpretations of erosion performance of short aramid fibre reinforced vinyl ester resin composites

Short aramid fibre reinforced vinyl ester resin based isotropic composites are fabricated with varying fibre weight fractions (20–50 wt%). The composites were evaluated for their erosion performance under a dynamic set of variables such as impingement angle (30°–90°), impact velocity (43–76 m/s), erodent size (250–600 μm) and stand-off distance (55–85 mm) following design of experiments (DOE) based on Taguchi analysis approach. The thermo-mechanical attributes such as storage modulus, loss modulus and damping properties as viscoelastic responses of the composites were investigated in the temperature range of 0–180 °C for their possible interpretations regarding reinforcement efficiency and energy dissipation aspects relevant to erosion process. An interrelation between the full-width half-maxima (FWHM) of loss modulus peak and erosion rate has emerged indicating the erosion to be mainly controlled by the fibre–matrix interfacial characteristics. The eroded surface morphology investigation by scanning electron microscopy (SEM) revealed the nature of wear-craters, material damage mode and other qualitative attributes responsible in facilitating erosion of the composites.

Influence of Carbon Nanotubes on Mechanical and Thermal Properties of Glass Fiber Reinforced Vinyl Ester Resin Composites

Carbon nanotubes (CNTs) were incorporated into glass fiber/ vinyl ester resins composites to improve their mechanical and thermal properties, especially the interlaminar shear and longitudinal compressive strengths which are belong to the matrix-dominanted properties and much weaker than the fiber-dominated properties. In this study, a higher temperature initiator was added to improve the polymerization degree and raise the transition temperature (Tg). Mechanical testing indicated that by adding 0.4 wt% CNTs, the nano-filled composites attributed to 21%, 16%, 10%, and 8% improvement in interlaminar shear strength, compressive strength, tensile strength and flexural strength with respect to their counterparts without CNTs, respectively. Moreover, Thermogravimetric analysis (TGA) also exhibits approximately 14°C higher decomposition temperature than those of conventional composites.

Thermal properties of sawdust reinforced vinyl ester composites post-cured in microwaves: A pilot study

The mechanical properties of sawdust reinforced vinyl ester resin composites post-cured in microwaves have been measured and evaluated in earlier studies. This basic but critical and important data have caused interests in the relevant industry in Australia. This study is therefore carried out to measure and evaluate the thermal properties of the composites with a view to benefit the civil and construction industry as the materials are used in the industry. The original contributions of this paper are that samples post-cured in microwaves, irrespective of the percentage by weight and particle size of sawdust, have higher glass transition temperatures than their counterparts post-cured in an oven; these imply that the stiffness of the samples post-cured in microwaves are higher than their peers. From previous study, it was discovered that the fracture toughness increased with increasing particulate loading. These properties are vital in civil engineering applications because civil structures need composites with high rigidity and fracture toughness. It is hoped that the discussions and results in this work would not only contribute towards the development of sawdust reinforced vinyl ester composites with better material properties, but also useful for the investigations of thermal and mechanical properties in other composites.

Thermo-mechanical correlations to erosion performance of short carbon fibre reinforced vinyl ester resin composites

Thermo-mechanical properties and erosion performance of short carbon fibre reinforced vinyl ester resin based isotropic polymer composites with four different fibre weight fractions have been investigated. The storage, loss and damping characteristics were analysed to assess the energy absorption/viscous recoverable energy dissipation and reinforcement efficiency of the composites as a function of fibre content in the temperature range of 0–140°C. The composite with 30wt.% of short carbon fibres has been observed to exhibit superior thermo-mechanical response with highest energy dissipation/damping ability accompanied with a constant storage modulus without any substantial decay till 60°C. The erosion rates (Er) of these composites are evaluated at different impingement angles (30–90°), fibre loadings (20–50wt.%), impact velocities (43–76m/s), stand-off distances (55–85mm) and erodent sizes (250–600μm) following the erosion test schedule in an air jet type test rig. An optimal parameter combination is determined and subsequently validated for erosion rate minimization following Taguchi method and by conducting confirmation experiments. A correlation between the loss-modulus inverse and the erosion rate has been observed which conceptually establishes a possible mechanistic equivalence between erosion and dynamic mechanical loading modes. The morphologies of eroded surface are examined by the scanning electron microscopy to investigate the nature of wear-craters, material damage mode and other qualitative attributes responsible for promoting erosion.

Mechanical and Wear Characterization of GF Reinforced Vinyl Ester Resin Composites with Different Co-Monomers

This article reports the mechanical characterization and sliding wear behavior of glass fiber-reinforced vinyl ester resins of varying acid values, based on epoxy-novalocs in the presence of three different comonomers (styrene, methyl acrylate and butyl acrylate) as reactive diluents. It presents a special account of the optimization of fabrication techniques of glass fiber-reinforced vinyl ester resin composites. It outlines optimum reaction conditions such as temperature, time, monomer type and initiator concentration. The experimental plan consisted of preparation of vinyl ester resin followed by the composite samples. Mechanical characterization was done and a comparison was made between the different samples. It was found that these composites have fairly good tensile and flexural properties. The composites with styrene and butyl acrylate as co-monomers had similar tensile strength which was higher than that of the composite with methyl acrylate. Hardness values of the three composites were almost the same without any significant effect of the comonomer type. Volumetric wear rate was estimated for these samples under various test conditions. A steady wear rate regime after certain amount of sliding was observed all the three cases.

Impact fatigue behaviour of carbon fibre-reinforced vinylester resin composites

Two types of unidirectional carbon fibre, one of high strength (DHMS) and another of medium strength (VLMS) reinforced vinylester resin composites have been examined for their impact fatigue behaviour over 104 impact cycles for the first time. The study was conducted using a pendulum type repeated impact apparatus specially designed and constructed for the purpose. A well-defined impact fatigue behaviour (S-N type curve) curve has been demonstrated. It showed a plateau region of 10–102 cycles immediately below the single cycle impact strength, followed by progressive endurance with decreasing impact loads, culminating in an endurance limit at about 71% and 85% of the single impact strength for DHMS-48 and VLMS-48, respectively. Analysis of the fractured surfaces revealed primary debonding, fibre breakage and pull-out at the tensile zone of the samples and a shear mode of fracture with breakage of fibre bundles at the compressive zone of the samples. The occurrence of a few major macrocracks in the matrix with fibre breakage at the high load-low endurance region and development of multiple microcracks in the matrix, coalescing and fibre breakage at the low-load-high endurance region have been inferred to explain the fatigue behaviour of the composites examined.