Vinyl Ester Polymer Research Articles

Investigation of the effects of scale and cure environment on the properties of vinyl ester polymer

This work involves the study of the cure kinetics of a commercial bisphenol-epoxy vinyl ester resin as a function of sample thickness and environment atmosphere. It has been previously suggested that cured vinyl ester polymer is a diphasic material consisting of a lower Tg styrene phase and a higher Tg vinyl ester phase. The cure kinetics of each phase have been observed to have a significant effect on the thermal properties of the system, such as the degree of crosslinking, glass transition temperature and final conversion. DSC, DMA and FTIR were employed to characterize two vinyl ester resin systems and study the material property transferability from macroscale to microscale. The effect of reduced styrene content on resin curing and polymer thermal behaviour was studied. The effect of oxygen interaction during initial cure was investigated at both microscale and macroscale and found to have a significant effect on final polymer performance.

A Study of the Moisture Absorption Characteristics of Vinyl Ester Polymer and Unidirectional Glass Fibre Vinyl Ester Laminates

A Study of the Moisture Absorption Characteristics of Vinyl Ester Polymer and Unidirectional Glass Fibre Vinyl Ester Laminates

Investigation of Mechanical and Thermal Stabilities of Tamarind Seed- and Peanut Shell Powder-Reinforced Vinyl Ester Composite

Efficient exploitation of agricultural waste results in a more sustainable and ecofriendly environment since it lessens the burden of their disposal, which has become increasingly important in recent times. Due to their high mechanical strength and high thermal stability, these biodegradable low-value agrosolid wastes have the potential to successfully replace synthetic fibers and fillers in polymer matrices in the form of reinforcements. This work deals with the addition of low-cost and renewable hybrid natural fillers, tamarind seed filler (TMS), and peanut shell powder (PNS) as particulate reinforcements to the vinyl ester (VE) resin. Traditional compression molding creates TMS/PNS-VE hybrid composites with filler loadings ranging from 5% to 30%. After the composites were fabricated, they were tested for strength properties and heat deflection temperature. A detailed experimental analysis of the mechanical properties was conducted. According to the findings, 20 wt.% hybrid filler loading to the vinyl ester polymer exhibited peak tensile, flexural, and impact strengths of 40.3 MPa, 142 MPa, and 16 kJ/m2, respectively, which is 1.52, 1.69, and 1.29 times the properties of the virgin polymer. However, the peak elongation at break 3.9% was obtained at 30 wt.%. Similarly, the heat deflection temperature (HDT) test of TMS/PNS-VE composites showed a maximum rise of 50.91% at 25 wt.% of filler loading. This is 1.51 times greater than the heat deflection temperature of the pure vinyl ester resin. The findings made it quite clear that adding 20 wt.% biosolid waste hybrid particulate fillers made out of tamarind seed and peanut shell to vinyl ester is the optimum weight, which improves the mechanical and thermal properties of the TMS/PNS-VE composite, making it suitable for making cost-effective materials for lightweight applications. This study also utilizes scanning electron microscopy (SEM) to investigate the microstructural characteristics of the composites, correlating these features with their mechanical performance.

Influence of twin-screw elements on dispersion of nano-clay in vinyl ester polymer composites using Taguchi’s orthogonal array technique

This work aims to experimentally investigate the influence of screw elements on the dispersion of Cloisite-15A in vinyl ester based on the design of experiments using MINITAB-V16 software. Experiments were designed considering two main factors such as Cloisite-15A loading (1, 2, 3, and 4 wt%) and type of screw elements with a varying number of kneading elements (type 1 with 55 mm, kneading elements and type 2 with 90 mm, kneading elements). The dispersion procedure of Cloisite-15A in vinyl ester was carried out by a combination of both ultrasonication and then twin-screw extrusion. The influence of these factors on the tensile strength and hardness was studied using an experimental layout possessing Taguchi’s L8 Orthogonal Array technique. ANOVA of the experimental results revealed the dispersion of Cloisite-15A with vinyl ester proved to be better when processed with type 2 screw elements having more kneading screws. The S/N ratio study showed that the Cloisite-15A loading had the greatest impact on the type 2 screw's tensile and hardness values for the Cloisite-15A/vinyl ester gel coats when treated at 230 rpm with 10 passes. The probability graphs led to the conclusion that, with a 95% confidence interval, all response values were distributed equally along the normal probability plot's trend. In order to achieve the best response in terms of mechanical strength, the Grey Relational Analysis (GRA) helped identify the best combination of process variables. This combination was known to be 4 wt% Cloisite-15A loading, with type 2 screw processed at 230 rpm with 10 passes. The SEM and XRD showed the absence of agglomeration and better exfoliation of Cloisite-15A in the gel coats with 4 wt% of clay loading.

The performance of novel polymer mortar containing vinyl ester resin reinforced by fly ash and iron sand under compressive, tensile, dan flexural test

Polymer concrete is a type of advanced concrete widely used globally in the last few decades. It is suitable for a variety of applications such as in pipes, roadway pavements, and bridge decks. Concrete can also be used sustainably to mitigate CO2 emissions due to the partial or total replacement of cement normally used as a binder with polymer. Several studies have explored polymer concrete materials and their applications but only a very few references were made to the mechanical properties and utilization of polymer mortar. One of the polymers most widely used is vinyl ester due to some advantages such as excellent corrosion and chemical resistance. Therefore, this study focused on examining the materials and compositions used in vinyl ester polymer mortar mixtures as well as their compressive, tensile, and flexural strength. The process involved conducting a preliminary test to assess the materials used in order to have an optimal composition. This was followed by the combination of the vinyl ester (VE) and its catalyst hardeners, mepoxe (ME) and cobalt (CO), fly ash (FA), and Lumajang iron sand (LIS) to determine compression strength, density, and cost with due consideration for the workability. Moreover, tensile and three-point bending tests were also applied to the materials. The results showed that the optimal content for the VE:ME:CO:FA:LIS was 42,2:2,9:0,63:18,1:36 with a compressive, tensile, and bending strengths of 92.64 MPa, 12.19 MPa, and 106.18 MPa, respectively. It was concluded that the novel polymer mortar has excellent mechanical properties and can be further implemented into structural elements such as pipes, beam-columns, slabs, walls, and others.

Mechanical and thermal characteristics of steam‐exploded silane grafted Kigelia Pinnata fruit (KPF) fiber reinforced vinyl ester polymer composites

AbstractThe cellulose‐rich Kigelia pinnata aqueous fruit (KPF) fiber is a valuable natural biomass and has drawn attention as a renewable resource. Vinyl ester polymer matrix composites with better interfacial properties can have higher mechanical and energy dissipation properties. It can be obtained by the use of steam‐exploded silane‐grafted KP fibers with various fractions incorporated in the polymer matrix. KPF fiber grafting was maximized at 5% concentration after a steam explosion, removing hemicelluloses and lignin, thereby enriching a 23% crystallinity index (CI), leading to rich cellulose fiber. Steam explosion along with silane grafting increases the interfacial adhesion of the KPF fibers and the matrix through the interfacial bonding structure of Si–O–Si bonds, as confirmed by FTIR. A fiber with greater tensile strength was used to fabricate the vinyl ester composites. The highest tensile value of the steam‐exploded silane surface‐modified 30% KPF fiber‐reinforced composite was 125 MPa compared to the unmodified one due to increased stress distribution and restricted polymer chain movements. Compared to the untreated 30% KPF fruit fiber composite, steam‐exploded silane‐treated fiber showed a 12% higher impact energy due to faster load transfer, causing more impact energy absorption. A relatively higher interlaminar shear strength was shown for 30% treated KPF composites than for 30% untreated KPF composites. The steam‐exploded silane‐treated fiber (30%) composite shows the greatest thermal decomposition temperature of 399 °C because silane‐surface‐treated fibers contact the organo‐functional silane group in the polymer matrix. As a result, it obstructs polymer chain motions at higher temperatures, causing increased bonding strength.

High Performance Carbon Fiber Structural Batteries Using Cellulose Nanocrystal Reinforced Polymer Electrolyte.

In recent years, structural batteries have received great attention for future automotive application in which a load-bearing car panel is used as an energy storage. However, based on the current advances, achieving both high ionic conductivity and mechanical performance has remained a challenge. To address this challenge, this study introduces a cellulose nanocrystal (CNC) reinforced structural battery electrolyte (CSBE) consisting of CNC, triethylene glycol dimethyl ether (TriG) electrolyte containing a quasi-solid additive, e.g., cyclohexanedimethanol (CHDM), in a vinyl ester polymer. This green and renewable CSBE electrolyte system was in situ polymerized via reaction induced phase transition to form a high performance multidimensional channel electrolyte to be used in structural carbon fiber-based battery fabrication. The effect of various concentrations of CNC on the electrolyte ionic conductivity and mechanical properties was obtained in their relation to intermolecular interactions, interpreted by FTIR, Raman, Li NMR results. Compared to the neat SBE system, the optimized CSBE nanocomposite containing 2 wt % CNC shows a remarkable ionic conductivity of 1.1 × 10-3 S cm-1 at 30 °C, which reveals ∼300% improvement, alongside higher thermal stability. Based on the FTIR, Raman, Li NMR results, the content of CNC in the CSBE structure plays a crucial role not only in the formation of cellulose network skeleton but also in physical interaction with polymer matrix, providing an efficient Li+ pathway through the electrolyte matrix. The carbon fiber composite was fabricated by 2 wt % CNC reinforced SBE electrolyte to evaluate as a battery half-cell. The results demonstrated that by addition of 2 wt % CNC into SBE system, 7.6% and 33.9% improvements were achieved in specific capacity at 0.33 C and tensile strength, respectively, implying outstanding potential of ion conduction and mechanical load transfer between the carbon fibers and the electrolyte.

The effect of environmental ageing on the interphase in glass fibre – vinyl ester composites

ABSTRACT The results of a study of environmental ageing on the apparent interfacial shear strength of glass fibre–vinyl ester microbond samples are presented. The scale related issues of estimating water absorption levels in microbond samples are reviewed and discussed and a solution based on Fickian diffusion is given. Interphase strength of microdroplets aged in water at 23°C was relatively stable up to 6 days exposure after which strength degradation was fairly rapid. Immersion in water at 50°C resulted in an immediate 20–30% irreversible loss of strength. Further exposure beyond 2 days led to total loss of integrity of the microbond samples. Electron microscope images of aged microdroplets appeared to show the development of a bi-phasic microstructure. The presence of two phases in small scale vinyl ester polymer samples was confirmed by DMA on thin films.

Untreated and chemically treated Pennisetum orientale grass fiber filled vinyl ester composites: Physical, mechanical, and thermal properties analysis

AbstractThe utilization of natural fibers rather than engineered filaments has turned into a subject of conversation in the composite industries. In this research, one of the natural fibers was synthesized from Pennisetum orientale grass and the surfaces were modified using sodium hydroxide (NaOH) chemically. Then they were used as reinforcement in vinyl ester polymer by different weight percentage (0, 5, 10, 15, 20, 25, and 30 wt%) for fabrication of composites. At different filler loading various mechanical properties were evaluated and discussed. The mechanical properties of the composites were observed to increase at beginning phase with increase in filler content till optimum (25 wt%) fiber loading and from there on declines. The composite at optimum fiber loading were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis and compared with untreated composites. The findings give manufactures and engineer a general idea to use this composite for weight reduction especially in automotive applications.

A spatial distribution effect of almond shell bio filler on physical, mechanical, thermal deflection and water absorption properties of vinyl ester polymer composite

AbstractThe present work deals with the effective utilization of almond shell bio‐waste fillers in the production of vinyl ester polymer composites. The almond shell particle surface was chemically modified by alkaline treatment. The almond shell particles with varying weight percentages of 5%–30% were used to prepare the vinyl ester polymer composite. The experimental results show that a 25% addition of alkaline‐treated almond shell particles significantly improved the mechanical properties of the composite when compared to pure vinyl ester and untreated almond‐filled composite samples. The highest tensile, flexural, impact strength, and Shore D hardness of the 25% alkaline‐treated almond shell composite were 54, 142 MPa, 31, and 79 kJ/m2, respectively. This was due to the alkaline treatment of almond shell particles, which improved the interfacial adhesion between the vinyl ester matrix and almond particles. The heat deflection temperature of the 25% alkaline treated almond shell particle‐filled vinyl ester matrix composite was 72°C. The thermal insulating characteristics of alkali‐treated almond shells were improved due to the reduction of quickly thermal degradable materials such as hemicelluloses and lignin, as indicated by Fourier transform infrared spectroscopic data, and more exposure of minerals to the surface, as confirmed by energy dispersive X‐ray analysis. The addition of alkaline‐treated almond shell particles improves the characteristics of the vinyl ester matrix and allows the development of biocomposites.

Failure analysis of basalt bidirectional mat reinforced micro/nano Sic particle filled vinyl ester polymer composites

Natural fiber reinforced polymer composites are increasingly used in composites industry to propel towards sustainable and environmentally friendly materials. Basalt fibers have superior mechanical and thermal properties, but are brittle by nature. However, appropriate filler materials were ingeniously utilized to subdue this impediment. Moreover, optimizing the content and appropriating the combination of micro and nano size filler particle addition has significant effects on the final mechanical properties of the composite. The failure pattern of bidirectional basalt fiber mat (67 wt%) vinyl ester composite with SiC filler of micro and nano size added independently as well as in combination at various proportion ranging from 2 wt% to 10 wt% was analysed using fractographic images. Highest tensile strength, flexural strength, impact strength, hardness and specific wear rate of 204.33 MPa, 525.33 MPa, 3.55 J/mm, 43.87 VHN and 5 × 10–7 mm3/Nm respectively was obtained for the optimized composite sample. The fractured scanning electron microscopy (SEM) images taken at different stress conditions reveal failure patterns, such as fiber–matrix delamination, matrix cracking, matrix deformation, matrix pores, fiber breakage, etc to correlate with the mechanical strength and wear resistance. The degree of damage is very well associated to the percentage content, size and combination of the filler material in the composite along with the fiber mat.

Mechanical, thermogravimetric, and dynamic mechanical analysis of basalt and flax fibers intertwined vinyl ester polymer composites

AbstractThe selection of fibers and their stacking sequence, which affect structural integrity and functional properties, are critical parts of polymer composite design. In this work, the influence of various stacking sequences made of basalt and flax fiber layers on the mechanical, thermal, and dynamic mechanical analyses of vinyl ester polymer composites was investigated. The stacking sequence designed by alternate basalt and flax layers showed higher tensile and flexural strengths, with basalt layers in the outer positions. The high‐strength basalt fiber retains considerable stress, particularly in the outer layer, reducing stress transfer to the remaining core layers. The basalt and flax fiber alternative layered sequence with outer basalt layers shows a slightly lower thermal degradation temperature (467°C) than the only basalt layered sequence composite (474°C). Because of the high thermal resistance of the outer basalt layers, heat flow to the next fiber layers is reduced. The dynamic mechanical analysis reveals that the polymer composite intertwined with only basalt fiber was found to have a higher storage modulus. On the other hand, the outer basalt layers intertwined with the core flax layers composite showed a 122% higher damping value than the stacking sequence made of only basalt fiber due to the porous structure of flax fibers dissipating more vibration energy.

Numerical characterization of the humidity effect on the fiber-matrix interface damage of hybrid composite material based on vinyl ester polymer matrix for engineering applications

Numerical characterization of the humidity effect on the fiber-matrix interface damage of hybrid composite material based on vinyl ester polymer matrix for engineering applications

Mechanical and drilling process characterisation of herringbone sisal fabric reinforced vinyl ester sandwich composites

ABSTRACT In the modern trend of industrial progress and technological development a natural fibre polymer composite plays a great demand in many of the structural applications. However, the problems associated with the machining of these composites lead to slowdown the consummations. Out of many machining methods, drilling is one among most repetitively used in the field of composites while joining. This work focused on drilling process optimisation using three different parameters, such as feed rate (mm/min), speed of spindle (rpm), drill diameter (mm). The sisal fibre herringbone pattern reinforced with vinyl ester polymer composite prepared using a conventional compression moulding technique. The results reveal that delamination factor at entry increases at lower (450rpm) and higher (1860,2700) spindle speed for 4 and 12 mm bit diameter, but feed rate various. The delamination factor at exit can be controlled at higher spindle speed (2700 rpm) with lower feed rate (30 mm/min) for 12 mm bit diameter. The drill diameter is having a significant effect on the delamination factor, both the entry and exit of the hole. Result reveals that for 2700 rpm spindle speed, 70 mm/min feed and 10 mm diameter exhibit minimum effort based on grey regression analysis.

Influence of environmental factors on the processes of biodegradation of vinylester composites

Polymer composite materials based on various binders are widely used in the construction industry. Polymer composites are characterized by high performance. Of great interest is the study of more economical compared to other polymers vinylester composites. They are successfully used in the US and European countries. In Russia, the use of polyester resin as a binder is not as common as abroad. At the same time, the influence of environmental factors on the biodegradation of vinyl ester polymer composites has not been sufficiently studied to date. This study is devoted to the study of the biostability of vinyl-ether composites under the influence of environmental factors. The most significant are the processes of atmospheric aging of materials, which include a complex effect of climatic and environmental factors. The study of changes in the species composition of microflora and indicators of resistance of composites, depending on their composition and operating conditions in the conditions of the seacoast.

Prediction of Structural Performance of Vinyl Ester Polymer Concrete Using FEM Elasto-Plastic Model.

This paper presents the methodology for predicting the mechanical performance of structural elements made of polymer concrete (PC). A vinyl ester polymer concrete composition and the results of experimental studies to determine the basic mechanical properties of the material are presented. Following the strategy for sustainable development in the building industry, the material cost of polymer concrete was lowered by reducing the consumption of raw materials and the partial replacing of the microfiller fraction with recycled waste products—calcium fly ash. An accurate computational model enabling stress analysis is a convenient way to verify the suitability of PC as a construction material in structural applications. Due to difficulty in deriving an accurate analytical formula, numerical approximation (finite element method) was used as a method for solving the problem. Constitutive modeling of PC is a very important aspect of the strength calculations and here it was done within the framework of elasto-plasticity. Numerical evaluation of the static bearing capacity of PC manhole covers is shown as an example of the proposed FEM methodology. The results of computer simulations were compared with laboratory tests. Finally, the adequacy of the numerical modeling for testing new construction and material improvements is discussed. The study showed that the concrete damaged plasticity material model can be effectively used for the description of PC mechanical behavior.

The effect of chestnut wood flour size on the mechanical properties of vinyl ester composites

Green composites are a special class of composites in which at least one of the components is obtained from natural resources. They are an alternative to traditional composites because of their useful properties such as biodegradability, low cost, easy processability, sound insulation and recycling. Green composites, which emerge as environmentally friendly polymeric composite materials, offer techno-economic advantages in commercial and engineering applications and are among the widely dealt subjects due to the very high demand from the global market. The aim of this study is to investigate the effect of chestnut wood flour size on the mechanical properties of chestnut-wood-flour-filled vinyl ester composites. With this aim, composite specimens were produced by using vinyl ester polymer as the matrix material and chestnut wood flour in three different sizes (0–150, 150–315 and 315–400 μm) as the natural filler. In each size combination, four different matrix/filler ratios (5, 10, 15 and 20% by weight) were adopted. These mixtures were then poured into Teflon moulds to produce the test specimens. Izod impact, three-point bending, hardness and tensile strength tests were performed on the composite specimens. In addition, morphological investigations were performed on the fractured surfaces of the specimens by using scanning electron microscopy. It is concluded that composites with a small-sized chestnut wood flour as the filler have superior properties for composite applications.

Raw and chemically treated bio‐waste filled (Limonia acidissima shell powder) vinyl ester composites: Physical, mechanical, moisture absorption properties, and microstructure analysis

AbstractThe rapid growth of environmentally sustainable and eco‐friendly materials tends to the utilization of biowastes as filler in polymer matrix composites. The particulate composite with improved wettability of fillers and advanced approach can evolve polymer composites that exhibit promising applications in packaging, automobile, marine, construction, and aerospace. In the present work, one of the biowaste fillers were synthesized from Limonia acidissima shells via a top‐down approach (pulverizing) and the surfaces were chemically modified using sodium hydroxide (NaOH) before they were used as fillers in vinyl ester polymer composites by different weight percentage (0, 5, 10, 15, and 20 wt%). The prepared particulate composites were characterized by mechanical properties, moisture absorption behavior, and morphology. At different filler loading the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, hardness, density, and moisture intake tests were performed. The results reveal that the properties increased for composites filled with alkaline treated fillers for the same filler loading and found to be higher at filler loading of 15 wt%. The morphological analysis confirms the better interfacial bonding between alkali‐treated particles and matrix due to the removal of non‐cellulose materials from the surface of the particles.

Cyclic Thermoresistivity of Freestanding and Polymer Embedded Carbon Nanotube Yarns

Carbon nanotube yarns (CNTYs) are hierarchical fibers with outstanding electrical properties, and understating the temperature‐dependence of their electrical resistance (thermoresistivity) is essential for sensing applications and development of self‐sensing polymer composites. The cyclic thermoresistive response of individual CNTYs and the effect of embedding the yarn into a polymer are experimentally investigated herein. The effect of confining the CNTY by a thermosetting polymer is addressed by studying the thermoresistive response of CNTY/vinyl ester single‐fiber composites. Heating–cooling cycles ranging from 25 (room temperature [RT]) to 100 °C and 25 to −30 °C are applied to individual CNTYs and to CNTYs embedded into a vinyl ester polymer, while their electrical resistance is simultaneously recorded. Both the CNTY and its single‐fiber composite show a negative dependence of electrical resistance with temperature. For both temperature ranges (above and below RT), the average temperature coefficient of resistance found for individual CNTYs is ≈−9.5 × 10−4 K−1, and its magnitude decreases about ≈30% when the yarn is embedded into the vinyl ester polymer. The hysteresis rendered by the different heating and cooling pathways is small for individual CNTYs, and largely increases when the CNTY is embedded into the polymer.

Static and dynamic behavior of micrometric agro Prunus amygdalus particulate distributed interpolymer layer‐kenaf composite

AbstractNatural fibers and fillers are playing a predominant role in enlightening the damping and mechanical properties of polymer material. The hybrid kenaf polymer composite was prepared using compression molding technique with the micrometric sized Prunus amygdalus fillers of 0, 5, 10, and 15 vol%, evenly distributed in the vinyl ester polymer interlayers. This work deals with the effect of variation in P. amygdalus content and the effect of chemical treatments like silane and alkaline treatment on the dynamic characteristics of fabricated composites. The kenaf woven fabric and P. amygdalus fillers were chemically treated using tri vinyl ethoxy silane and sodium hydroxide (NaOH) solution to modify their surface characteristics. The effect of chemical treatment on the kenaf fiber and P. amygdalus filler was characterized using Fourier transform infrared spectroscopy. From experiments, it is observed that chemical treatment removes the strength reducing substances like lignin, hemicellulose and wax from the kenaf fiber and P. amygdalus filler surfaces. The addition of filler and chemical treatment increase the tensile strength to 56 MPa and flexural strength to 89 MPa. Silane‐treatedP. amygdalus filler with 10% composite, reveals higher storage modulus of 4.71 GPa than the alkaline and untreated composites in all tested frequencies. This may be due to enhanced tensile modulus and better interfacial bonding between P. amygdalus filler and vinyl ester matrix. Fractography was studied using micrographs of the scanning electron microscope. The result shows the predominance of brittle mode of failure in all types of fabricated composites. This kind of industrial agro waste hybrid composite can be considered as an effective damping material.