Properties Of Vinyl Ester Resins Research Articles

A novel phosphorus/nitrogen-containing vinyl imidazolium ionic liquid for improving flame retardancy and mechanical properties of vinyl ester resin, and its carbon fiber composites

In daily life, the application of vinyl ester resin (VER) and its carbon fiber composites is limited by their flame retardancy and mechanical properties. In this work, we synthesized an ionic liquid, VIDHP, from diethyl hydroxymethyl phosphate (DHP) and 1-vinylimidazole (VIM). VIDHP can not only cross-links with VER but also enhances the interaction between the resin and the carbon fiber. The flame retardancy and mechanical properties of VER and its carbon fiber composites were effectively improved by the addition of VIDHP. In particular, the addition of 15 wt% VIDHP increased the flexural strength and flexural modulus of the carbon fiber composites by 29.3 % and 42.4 %, while reducing the total heat release and total smoke release by 15.4 % and 18.4 %. The flame retardant mechanism of VIDHP was also investigated. This approach provides a new idea to improve the flame retardant and mechanical properties of VER and its carbon fiber composites.

An intrinsic flame‐retardant and heat‐resistant vinyl ester resin by crosslinking with diisocyanate, styrene and phosphorus‐containing hydroxyl compound

AbstractIn this work, 2‐(6‐oxido‐6H‐dibenz<c,e><1,2>oxaphosphorin‐6‐yl)‐methanol (ODOPM) was synthesized, and covalently introduced into vinyl ester resin (VER) by combining with 4,4′‐diphenylmethane diisocyanate (MDI). The influences of ODOPM and MDI on the thermal properties, flame retardancy, and flame‐retardant mode‐of‐action of the resin were investigated. When the phosphorus addition reaches 1.3 wt%, the limiting oxygen index (LOI) of VER/ODOPM‐1.3 boosts to 30.3% and vertical burning (UL‐94) rating increases to V‐0. Compared with the virgin VER, the peak heat release rate (PHRR) and total heat release (THR) of VER/ODOPM‐1.3 are significantly reduced by 64.2% and 35.1%, respectively. The introduction of ODOPM and MDI significantly enhances the flame retardancy of VER. ODOPM and MDI are chemically linked to the polymer network of VER, which increases the glass transition temperature (Tg) and rigidity. This work offers a facile method for improving both thermal and flame‐retardant properties of vinyl ester resin.

Effect of colemanite mineral on gamma radiation attenuation properties of vinyl ester resin

In this study, it is aimed to experimentally and theoretically obtain the gamma radiation attenuation properties of vinyl ester resin (VE) containing different rates of colemanite (CO) mineral and to compare these results. In the first stage, experimental measurements were performed using a gamma spectroscopy system containing a NaI(Tl) detector at three different gamma energies (511, 835 and 1275 keV) emitted from two different radioactive sources (22Na and 54Mn). As a result of the experiments, linear attenuation coefficients (LACs) of VE samples were obtained. The variation of LACs according to the density of the samples were investigated. The obtained results showed that LACs increased the density of the VE samples increased. Using the experimental LAC results, the half (HVL) and tenth (TVL) value layer thickness, mean free path (MFP) and transmission rate values were calculated. In the second stage of the study, LACs were calculated theoretically with the help of XCOM code using the chemical contents of VE samples. As a result of the comparison of the LACs obtained experimentally and using the XCOM code, it was observed that they were in good agreement. In addition, the results obtained with the XCOM code gave information about the variation of the attenuation coefficient in different energy regions. Based on all these data, it was concluded that as the amount of colemanite in the vinyl ester resin examined in the study increased, the gamma radiation shielding performance increased.

Achieving superior anti-corrosion properties of vinyl ester resin coatings via compositing with 3-methacryloxy propyl trimethoxysilane functionalized MXene nanosheets

Exposure of steel to harsh marine environment can cause serious corrosion, which significantly affects its durability. In this study, a novel two-dimensional MXene nanosheets were functionalized with 3-methacryloxy propyl trimethoxysilane (γ-MPS@MXene) followed by introducing into the vinyl ester resin (VER) through solution blending method to enhance the anti-corrosion properties of the coatings. The effects of γ-MPS@MXene incorporation on the mechanical properties, thermal stability, dynamic thermo-mechanical properties, UV aging resistance, anti-corrosion properties of the VER nanocomposites were systematically investigated. The optimum tensile strength, elastic modulus, hardness, thermal stability and UV aging resistance of γ-MPS@MXene VER nanocomposites can be achieved when composited with 0.08 wt% γ-MPS@MXene. The electrochemical impedance spectroscopy(EIS) results demonstrate the introduction of γ-MPS@MXene nanosheets into the VER enhanced the anti-corrosion properties of the composites coating remarkablely and the anti-corrosion mechanism was also revealed. The favourable interfacial interaction between γ-MPS@MXene and VER matrix through covalent cross-linking diminished interfacial defects of the composite coating and was also beneficial to enhancement of the compatibility, the well-dispersed γ-MPS@MXene in VER created a “labyrinth effect”, which prolonged the diffusion path of corrosive medium to the carbon steel substrate. This research provides a promising strategy for the fabrication of heavy anti-corrosion nanocomposite resin coatings, which can realize long-term corrosion protection of metal substrates.

Effect of Nanofillers on the Mechanical Properties of Vinyl Ester Resin Used as a Carbon Fiber Reinforced Polymer Matrix

Effect of Nanofillers on the Mechanical Properties of Vinyl Ester Resin Used as a Carbon Fiber Reinforced Polymer Matrix

Improved mechanical and flame resistance properties of vinyl ester resin composites by lithium containing polyhedral oligomeric phenyl silsesquioxane

AbstractThe mechanical and flame retardancy properties of vinyl ester resin (VER) composites containing lithium containing polyhedral oligomeric phenyl silsesquioxane (Li‐Ph‐POSS) are investigated. The bending test suggests that Li‐Ph‐POSS improves the mechanical property of the matrix. Compared with the pure VER, the bending strength and flexural modulus are improved by 42.9% and 18.9% with the addition of 3 wt% Li‐Ph‐POSS, respectively. And cone calorimeter test results indicate that Li‐Ph‐POSS endows the matrix good fire resistance. Three weight percent Li‐Ph‐POSS makes the heat release rate (HRR) decline by 32.4% compared with the pure VER. Besides, 3 wt% Li‐Ph‐POSS performs best on smoke suppression and declines the release of CO due to good char‐forming effect of Li‐Ph‐POSS. The improvement of mechanical property and the slightly improved glass transition temperature (Tg) of VER composites confirmed the excellent compatibility between Li‐Ph‐POSS and the matrix. The flame retardant mechanism is revealed by Thermogravimetric coupled with Fourier transform infrared analysis, scanning electron microscopy, and X‐ray photoelectron spectroscopy analysis in detail. The work provides an optional method to prepare flame retarded VER with excellent mechanical properties.

The effect of impurities in reactive diluents prepared from lignin model compounds on the properties of vinyl ester resins

ABSTRACTVinyl ester resins (VERs) often contain high concentrations of a petroleum‐based reactive diluent, such as styrene. Reactive diluents that can be derived from lignin, including phenyl methacrylate (PM), 2‐methoxyphenyl methacrylate (MG), and 4‐propyl‐2‐methoxyphenyl methacrylate (M4PG), were synthesized and investigated as potential styrene replacements. A commercial VER was blended with each lignin‐derived reactive diluent, and styrene, in 7:3 and 1:1 weight ratios and cured to ≥ 94%, based on near‐IR spectral analysis. The substituents on the aromatic ring of the lignin‐derived reactive diluent are shown to have small effects on viscosity, thermogravimetric, and thermomechanical properties of the cured resins, where, in general, the smaller the reactive diluent, the greater the glass‐transition temperature (Tg) and the lower the viscosity. Increasing purity of the reactive diluents through chromatographic separations substantially increases the Tg and degradation temperatures of the resins. The results suggest that PM, MG, and M4PG are effective bio‐based reactive diluent replacements for styrene. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43817.

Assessment Effect of Surface Modification of Nano Alumina with Vinyl Trimethoxy Silane to Mechanical Properties of Vinyl Ester Resin

This paper reports Surface treatment of nano alumina with vinyl silane coupling agents was performed. Modification with silane coupling agents is commonly method by which the interfacial interaction of particles can be enhanced with resin. Surface treatment of nano alumina was implement under hydrolysis and condensation condition at different silane concentration. The surface characteristics of the unmodified and modified aluminum pigments were investigated by means of CH and FTIR analyses. The Mechanical properties of vinyl ester resin was investigated by the Dynamic mechanical thermal Analysis (DMTA). Results revealed that vinyl silane adsorbed on the surface of alumina under sol-gel reaction. Also, the mechanical properties of the vinyl ester composite was significantly enhanced with surface treated particles.

Studies on thermal and viscoelastic properties of vinyl ester resin and its composites with glass fiber

Vinyl ester resins are widely used in sandwich composite structures. Because of their good resistance to chemicals, flexibility and easy processing, these sandwich are extensively applied in the marine sector. These composites are typically manufactured by liquid molding processes, especially infusion. In this study, RTM light was used to inject the polymeric resin into the mold cavity, flowing in the space between the impermeable core and the mold walls, where the fibrous medium was. In this process, viscosity, gel time and curing time of the resin are very important parameters. This work addressed the curing and post-curing characteristics of a vinyl ester resin, and also the characteristics of neat and reinforced vinyl ester using dynamic mechanical analysis (DMA). The increase in shear rate did not significantly influence resin viscosity within the studied range. Differential scanning calorimetry showed the efficiency of the post-curing stage, with the decrease in residual enthalpy. With DMA, it was possible to determine gel time and gel temperature, which yielded similar values to those found by the SPI (Society of the Plastics Industry) method, indicating that the simpler SPI method can be reliably used for that.

Influence of post-curing temperature on the structure, properties, and adhesion of vinyl ester adhesive

Vinyl ester (VE) resins are widely used as thermoset adhesives in structural joints and composites, but complete curing under environmental conditions is not produced. The existing literature dealing with the effect of post-curing on the structure, viscoelastic, mechanical, and adhesion properties of VE resin is scarce. Therefore, in this study, VE resin was subjected to different post-curing temperatures (50–140 °C) for one hour, and the changes in structure and properties were assessed. The degree of cross-linking of the VE resin depended on the post-curing temperature and cure started to be completed above 100 °C, a temperature close to the glass transition temperature (115 °C) of the completely cross-linked polymer. Furthermore, gel formation in VE resin was evidenced for post-curing temperature below 100 °C. In order to fully cross-link the VE resin, post-curing at 140 °C for one hour was necessary, and it was evidenced by an increase in the glass transition temperature and in the mechanical properties; an increase in adhesion to cold rolled steel was obtained although the shear strength was lower than in the joint produced with the non-post-cured VE resin.

Vinyl ester resin: Rheological behaviors, curing kinetics, thermomechanical, and tensile properties

The effects of isothermal temperature on the curing extent, gel time, dynamic rheological behaviors, and mechanical properties of vinyl ester resins (VERs) were systematically studied. Although, the curing extent was observed increase with increasing the operating temperature, the study of residual heat of cured VERs indicated that the final curing extent depended on the postcuring process. The values of shear storage and loss modulii at gel point were observed to decrease with increasing both the isothermal temperature and heating rate, which were associated with the formation of microgels during the gelation process. With increasing isothermal temperature and heating rate, the microgel did not have enough time to grow well, causing a reduced shear storage and loss modulii at the gel time. The storage and loss modulii of the cured VERs were also studied and shown that with temperature increased to the glass transition, both modulii were first decreased and then increased. © 2013 American Institute of Chemical Engineers AIChE J, 60: 266–274, 2014

Structure and properties of vinyl ester resins modified with organophilic synthetic layered silicates bearing non- and co-reactive intercalants

OLS were incorporated in various amounts (0.1 to 5 wt.%) in VE. The intercalants of synthetic fluorohectorite were TMDA and OAE, respectively. The latter quaternary amine was expected to support the intercalation/exfoliation of the silicate by participating in the crosslinking reactions. Both OLS types became intercalated based on X-ray diffractograms. DMTA displayed a slight increase in the stiffness by adding OLS. The glass transition temperature did not change practically with the OLS type and content. Fracture mechanical tests were performed on CT specimens. Both the fracture toughness (Kc,maximum improvement ca. 45%) and fracture energy (Gc, maximum improvement ca. 100%) increased with increasing OLS content. As expected, OAE proved to be a more suitable intercalant than TMDA in respect to the overall property profile. The failure mode of the specimens was studied in a SEM and discussed. The fractographic inspection revealed that the composites contained abundant OLS microparticles triggering crack pinning and crack bifurcations.

Contrasts on Fracture Toughness and Flexural Strength of Varying Percentages of SLG-reinforced Phenolic Composites

Many previous studies had reported the improvement in the mechanical properties of vinyl ester resin reinforced with SLG. Among these material properties, fracture toughness and flexural properties are important material characteristics. This article investigates the relationship between these two sets of material properties in envirospheres (SLG)-reinforced phenolic composites. The material properties of the phenolic resin composites containing different percentage by weight of SLG are experimentally measured using the short bar method and the three-point test. The findings indicated that the PF/E-SPHERES (30%) constitute the best compromise with respect to cost, fracture toughness, and flexural strength. It is hoped that the discussion and results in this work would not only contribute towards the development of SLG-reinforced phenolic composites with better material properties, but also be useful for the investigations of fracture toughness and flexural strength in other composites.

Contrasts on Fracture Toughness and Flexural Strength of Varying Percentages of SLG-reinforced Phenolic Composites

Many previous studies had reported the improvement in the mechanical properties of vinyl ester resin reinforced with SLG. Among these material properties, fracture toughness and flexural properties are important material characteristics. This article investigates the relationship between these two sets of material properties in envirospheres (SLG)-reinforced phenolic composites. The material properties of the phenolic resin composites containing different percentage by weight of SLG are experimentally measured using the short bar method and the three-point test. The findings indicated that the PF/E-SPHERES (30%) constitute the best compromise with respect to cost, fracture toughness, and flexural strength. It is hoped that the discussion and results in this work would not only contribute towards the development of SLG-reinforced phenolic composites with better material properties, but also be useful for the investigations of fracture toughness and flexural strength in other composites.

Effect of the degree of cure on the viscoelastic properties of vinyl ester resins

Dynamic mechanical thermal analysis (DMTA) was performed on model vinyl ester resin (VER) samples prepared from bisGMA and styrene, partially cured using either benzoin ethyl ether (BEE) as a conventional photoinitiator or p-xylylene bis-( N, N-diethyldithiocarbamate) (XDT) as a photoiniferter, and on fully cured samples using benzoyl peroxide as a thermal initiator. Thermogravimetric studies showed that minimal styrene monomer was lost during the DMTA experiments. The DMTA experiments for the samples partially cured using BEE revealed two plateaus in the storage modulus and two peaks in the tan δ curves, attributed to trapped radicals gaining mobility and continuing polymerization after the samples were heated beyond their initial T g. Only a single transition was observed for samples cured using XDT because this system did not contain trapped radicals. Performing photopolymerizations with XDT thus allowed us to probe the effect of cure conditions on the glass transition temperature, rubber modulus and relaxational behaviour of partially cured resins. The breadth of the glass transition was characterized in the temperature and frequency domains (obtained by time–temperature superposition). Partially cured bisGMA/styrene blends showed a narrowing of the transition in the frequency domain with increased cure but the bisGMA system showed no variation. When partially and fully cured bisGMA/styrene blends were studied, the breadths of the frequency domains showed opposite trends as the styrene concentration was varied. Thus, the breadth of the transition could not be interpreted as a simple measure of the network heterogeneity but is believed to be related to the distribution of mobilities in the network structure which determine the distribution of relaxation times. Time–temperature superposition yielded shift factors which, when fitted to the WLF equation, indicated that the free volume at the glass transition temperature ( T g) and the free volume expansion coefficient depended on both crosslink density and also the ability of the monomer units to pack into the network.

Effects of initiators on the cure kinetics and mechanical properties of vinyl ester resins

AbstractInitiators play an important role in the curing of vinyl ester resins. In this study, two kinds of initiators were used to investigate the effects of initiator systems on the cure kinetics, microstructure, and mechanical properties of vinyl ester resins. The reaction kinetics, investigated with isothermal differential scanning calorimetry (DSC), showed that the combination of different kinds of initiators could significantly decrease the induction times and exothermal peak times and increase the amount of isothermal reaction heat in comparison with a single‐initiator system. The residual heat of the isothermal cure of vinyl ester resins, obtained by DSC, demonstrated the existence of microheterogeneity in the cured resins. The DSC data also showed that the highly crosslinked phase (the microgel phase) was more perfect for the resins cured with an initiator‐combination system. No significant difference was observed in the mechanical properties of resins cured under different conditions, whereas the cure temperature had a great effect on the mechanical properties of cured resins. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of structure on mechanical properties of vinyl ester resins and their glass fiber-reinforced composites

The article describes the effect of structure of vinyl ester resins (VE) on the mechanical properties of neat sheets as well as glass fabric-reinforced composites. Different samples of VE were prepared by reacting ester of hexahydrophthalic anhydride (ER) and methacrylic acid (MAA) (1 : 1 molar ratio) followed by reaction of monomethacrylate terminated epoxy resin with glutaric (E) or adipic (F) or sebacic acid (G) (2 : 1 molar ratio). The neat VE were diluted with styrene and sheets were fabricated by using a glass mold. A significant reduction in the mechanical properties was observed by increasing the methylene content of resin backbone (i.e., sample E to G). Glass fabric-reinforced composites were fabricated by vacuum assisted resin transfer molding (VARTM) technique. Resin content in the laminates was 50 ± 5 wt %. Increase in the number of methylene groups in the vinyl ester resin (i.e., increasing the bridge length) did not show any significant effect on limiting oxygen index (LOI) value (21 ± 1) of the laminates but tensile strength, tensile modulus, flexural strength, and flexural modulus all increased though these values are significantly lower than observed in laminates based on resin B. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Wetting behavior of modified vinylester resins on the surface of UHMWPE materials

A new testing method was used to observe on-line the dynamic wetting course of liquid resins on PE fabric. The measure procedures and data processing were introduced in detail. To aim at some applications of vinylester resins/polyethylene fiber composites, vinylester resins (VRs) were at first modified by three kinds of additives, including elastomer, liquid rubber and isocyanate-terminated prepolymer. Then the wetting behaviors of these modified resins on the surface polyethylene (PE) materials were observed. After they were modified by six kinds of elastomers, the infiltrate-steady-times of these resins on the surface of PE fabric all increased; only the contact angle of natural rubber-modified VR on the surface of PE film decreased. After VRs were toughened by three kinds of liquid rubbers, their wetting velocities all became slower and the contact angles on the surface of PE film all decreased. In addition, VRs were also modified by three kinds of isocyanate-terminated prepolymers, which were the products of different hydroxyl-terminated polymers reacted with methylene bisphenyl isocyanate and whose structures were characterized by means of GPC, DSC and FT-IR, respectively. The wetting state of these modified resins on the surface of PE materials suggested that the interfacial compatibility of modified VRs and PE fabric did not decrease at the same time when the other properties of vinylester resins changed.

Properties of vinyl ester resins containing methacrylated fatty acid comonomer: the effect of fatty acid chain length

AbstractThis paper reports the formulation of a low‐cost vinyl ester‐based composite resin suitable for liquid molding, which has significantly lower volatile organic compound emission associated with it. Methacrylated fatty acid comonomers were used to replace the conventional yet environmentally hazardous reactive diluent, styrene. The chain length of these fatty acids played a key role in obtaining better viscosity, as it was proved to affect two interplaying factors: intermolecular friction and hydrogen bonding. The thermomechanical performance was greatly affected by the chain length of the fatty acids as well as the crosslink density of the polymer networks. A carbon number of 6 to 8 was good enough in optimizing the viscosity parameter suitable for handling; the dynamic mechanical analysis values, namely glass transition temperature and storage modulus, were in the range 66–121 °C and 0.97–2.8 GPa, respectively, as the carbon number was varied from 4 to 16, making the material suitable for various applications. Microstructures obtained from scanning electron microscopy results were correlated with polymer properties to obtain a better insight into these polymer networks. Copyright © 2007 Society of Chemical Industry

The influence of silane coupling agents on the polymer mortar

The aim of this work is to investigate the influence of silane coupling agents on the properties of vinylester resin and vinylester mortar. Research work is focused on two methods of modification: direct silane addition to the resin binder and the use of silane pre-treated silica flour as a filler. The results of such modification are described, taking into consideration mixture viscosity, curing conditions, mechanical strength and fracture process. The test results indicated that silane coupling agent can decrease the viscosity of the mortar mixture, extend its pot life, enhance its mechanical strength and resistance for fracture. However, changes in the curing process, which may be disadvantageous and the increase of composite brittleness were noticed and stressed.