Behavior Of Unsaturated Polyester Resin Research Articles

Unravelling the thermal behavior and kinetics of unsaturated polyester resin supplemented with organo-nanoclay.

The integration of nanoclays within polymeric systems to develop high-performance materials is an emerging research field that has garnered significant attention. In this context, an organically modified montmorillonite (OMMT) is utilized as a reinforcing agent for unsaturated polyester resin (UPR) with loads of 1%, 3%, and 5 wt%. The modification of montmorillonite nanoclay (MMT) using a quaternary ammonium compound is performed through an effective repetitive modification process under reflux conditions. The curing behavior of the unsaturated polyester resin containing organically modified clay catalyzed with methyl ethyl ketone peroxide (MEKP) initiator and promoted by cobalt naphthenate accelerator is investigated using dynamic differential scanning calorimetry (DSC) followed by kinetic analysis using isoconversional methods. The dynamic DSC curing curves showed a bimodal exothermic peak, where two independent reactions, namely, redox and thermal decomposition of the initiator occurred. In this study, novel insights into the curing reaction of the studied UPR and UPR/OMMT systems have been revealed through the application of the Trache-Abdelaziz-Siwani (TAS) and Sbirrazzuoli (VYA/CE) isoconversional methods. These methods have enabled the elucidation of the intricate mechanisms and phenomena that impact the curing reaction, including the dilution effect in the redox reaction and the diffusion phenomenon at the end of the thermal decomposition reaction. The incorporation of nanoclay into unsaturated polyester resin (UPR) resulted in a reduction in the activation energy for both the redox and thermal reactions. Specifically, the energetic barrier decreased from 93.85 and 101.58 kJ mol-1 for pristine UPR to 60.71 and 72.93 kJ mol-1 for UPR/OMMT-5 in the redox and thermal reactions, respectively. The addition of OMMT caused a significant decrease in the pre-exponential factor. The values of UPR/OMMT-5 were 2.75 × 105 and 5.50 × 106 for the redox and thermal decomposition reactions, respectively, compared to 1.41 × 1012 and 5.13 × 1013 for UPR. The thermogravimetric analysis demonstrated that UPR/OMMT systems were more stable than UPR.

Moisture Resistance, Thermal Stability and Fire Behavior of Unsaturated Polyester Resin Modified with L-histidinium Dihydrogen Phosphate-Phosphoric Acid.

In this paper, the fire behavior of unsaturated polyester resin (UP) modified with L-histidinium dihydrogen phosphate-phosphoric acid (LHP), being a novel intumescent fire retardant (IFR), was investigated. Thermal and thermomechanical properties of the UP with different amounts of LHP (from 10 to 30 wt. %) were determined by thermogravimetric analysis (TG) as well as dynamic mechanical thermal analysis (DMTA). Reaction to small flames was studied by horizontal burning (HB) test, while fire behavior and smoke emission were investigated with the cone calorimeter (CC) and smoke density chamber. Further, the analysis of volatile products was conducted (TGA/FT-IR). It was observed that the addition of LHP resulted in the formation of carbonaceous char inhibiting the thermal decomposition, burning rate and smoke emission. The most promising results were obtained for the UP containing 30 wt. % of LHP, for which the highest reduction in maximum values of heat release rate (200 kW/m2) and total smoke release (3535 m2/m2) compared to unmodified polymer (792 kW/m2 and 6895 m2/m2) were recorded. However, some important disadvantage with respect to water resistance was observed.

Evaluation of tensile and flexural properties of foundry slag reinforced particulate polymer composite

Mechanical behaviour of unsaturated polyester resin reinforced with foundry slag is used for the composite materials has been studied to determine various important parameters, such as tensile and flexural properties by using moulding process. 75 µm level particle sizes of fine powdered foundry slag are used for sample preparation. Concentration of powdered slag is varied from 5%, 7.5%, 15% by weight in the polyester resin. The composite test specimens are prepared using moulding process as per ASTM D638 for tensile test and ASTM D 790 for Flexural test.

Wear Behavior Performance of Polymeric Matrix Composites Using Taguchi Experiments

This research estimates the effect of independent factors like filler (3%, 6%, 9%, 11% weight fraction), normal load (5N, 10N, 15N), and time sliding (5,7 , 9 minutes) on wear behavior of unsaturated polyester resin reinforced with jute fiber and waste eggshell and, rice husk powder composites by utilizing a statistical approach. The specimens polymeric composite prepared from resin unsaturated polyester filled with (4% weight fraction) jute fiber, and (3%, 6%, 9%, 11% weight fraction) eggshell, and rice husk by utilizing (hand lay-up) molding. Dry sliding wear experiments were carried utilizing a standard (pin on disc test setup) following a well designed empirical schedule that depends on Taguchi’s experimental design L9 (MINITAB 16) with the determined (S/N) ratio and analysis of different (ANOVA) optimal factors to minimize the wear rate. Results exhibit that the presence the of 11% weight fraction eggshell and rice husk powder with 4% weight fraction jute fiber improves the wear resistance of unsaturated polyester composite materials significantly. The filler content was observed to be the major significant factor influencing the wear rate followed by time sliding and normal load. From the results of the S/N ratio, the optimization of wear parameters is obtained at specimens A3, A6, A7, and A10 as to minimize wear rate.

The Effect of Glass and Carbon Fibers and Powders Addition on the Sliding Wear Behavior of Unsaturated Polyester Resin

The Effect of Glass and Carbon Fibers and Powders Addition on the Sliding Wear Behavior of Unsaturated Polyester Resin

Curing behaviour of unsaturated polyester resin and interfacial shear stress of sugar palm fibre

Studies on the effect of cobalt of unsaturated polyester resin and the effect of treated sugar palm fibre with sodium hydroxide on single fibre strength and interfacial shear strength (IFSS) are presented in this paper. 1% of methyl ethyl ketone peroxide was used as the initiator, while cobalt of variable percentages (0.05%, 0.1%, 0.2%, 0.4 %,0.6%, 0.8% and 1%)was used as the hardener. The effects on glass transition and exothermic reaction of unsaturated polyester were studied for post curing temperature determination using differential scanning calorimetry by heating the samples at 10oC/min heating rate from 30oC to 120oC with flowing of purge nitrogen gas atmosphere . For the single fibre test and IFSS, the treatment was carried out using sodium hydroxide solution with 1% concentration for one hour soaking time. Based on the optimisation percentage of cobalt, it was found that the higher the percentage of cobalt, the faster the sample tested to gel and cured. Treated sugar palm fibre exhibited better single fibre strength and IFSS between the matrices compared to untreated fibre due to the effectiveness of the alkali treatment. This can be attributed to the rearrangement of fibrils along the direction of tensile force and the removal of the coating layer and impurities after the alkaline treatment.

Optimizing cure cycle of nanoclay-reinforced unsaturated polyester resins considering various curing kinetic models

In this research, a method has been presented for optimizing cure cycle of neat unsaturated polyester resin and polyester resin containing 3 wt% nanoclay Cloisite® 10 A (UP/10 A) and nanoclay Cloisite® 30B (UP/30B) in thin components. We refer to this optimization method as the directed grid search method. To model cure behaviour of unsaturated polyester resin, four different kinetic models were considered, including advanced iso-conversional method, Kamal method, Kamal method with Chern diffusion factor, and Kamal method with Sbirrazzuoli diffusion factor. The comparison of our proposed optimized cure cycles indicates that addition of nanoclay to the resin causes the cure cycle duration and also the maximum temperature during the cure to decrease. In addition, by adding nanoclay to the resin, the optimal cure cycle is transformed from a five-stage cure cycle to a four-stage one. Our investigations indicate that optimal cure cycles for the UP/10 A and UP/30B systems do not significantly differ. This is because the pre-exponential factor can influence the optimal cure cycle as much as the activation energy. Our results show that the optimal cure cycle obtained from the Kamal model is much shorter than the optimal cure cycle obtained from the advanced iso-conversional method, while the optimal cure cycle obtained from the Kamal model with Chern diffusion factor is very similar to the cure cycle resulting from the advanced iso-conversional method.

The effect of defect-rich molybdenum disulfide nanosheets with phosphorus, nitrogen and silicon elements on mechanical, thermal, and fire behaviors of unsaturated polyester composites

The article demonstrates the method of engineering defects into molybdenum disulfide surface to facilitate dithioglycol conjugation. The molybdenum disulfide (MoS2) nanosheets containing phosphorus, nitrogen and silicon elements were successfully synthesized by a “thiol-ene” click reaction between defect-rich MoS2 nanosheets with sulfydryl groups and ene-terminated hyperbranched polyphosphate acrylate (HPA) and characterized by FTIR and XPS to confirm covalent functionalization through C–S bond. The influence of MoS2-HPA on combustion behavior of unsaturated polyester resin (UPR) composites was investigated by cone calorimeter, demonstrating the obvious reduction of 43.2% and 39.6% in Peak Heat Release Rate and Total Heat Release. TG-IR-MS coupling technique was utilized to reveal thermal degradation and identify toxic volatiles such as CO, benzene, methylbenzene. Based on gaseous and condensed phase, we reasonably proposed the flame-retardant mechanism of MoS2-HPA/UPR composites. Moreover, mechanical properties and thermal stability of UPR matrix have significantly improved, due to the incorporation of MoS2-HPA hybrids. It is anticipated to exploit covalent functionalization of MoS2 nanosheets and MoS2-based composites with high performance.

DSC Cure Kinetics of an Unsaturated Polyester Resin Using Empirical Kinetic Model

In this paper, the kinetics of curing of unsaturated polyester resin initiated with benzoyl peroxide was studied. In case of unsaturated polyester (UP) resin, isothermal test alone could not predict correctly the curing time of UP resin. Therefore, isothermal kinetic analysis through isoconventional adjustment was used to correctly predict the curing time and temperature of UP resin. Isothermal kinetic analysis through isoconversional adjustment indicated that 97% of UP resin cures in 33 min at 120 °C. Curing of UP resin through microwaves was also studied and found that 67% of UP resin cures in 1 min at 120 °C. The crosslinking reaction of UP resin is so fast at 120 °C that it becomes impossible to predict correctly the curing time of UP resin using isothermal test and the burial of C=C bonds in microgels makes it impossible to be fully cured by microwaves at 120 °C. The rheological behaviour of unsaturated polyester resin was also studied to observe the change in viscosity with respect to time and temperature.

Prediction of Long – Term Creep Properties of Kenaf Fiber Unsaturated Polyester Composites

This research focuses on predicting long-term behavior of unsaturated polyester resin (UP) and kenaf unsaturated polyester composite. The objectives of these tests are to establish a relationship between stress, strain and time at constant loading and temperature. The results obtained from these tests are used in predicting the life and strength of the polymer material. Based on the 1,000 hours experimental data, curve fitting and Findley Power Law models are employed to predict long-term behavior of the material. The results showed that curve fitting model accurately predicted the non-linear time dependent creep deformation of these materials with acceptable accuracy.

The Effect of (E-glass) Fibers and Glass Powder Addition on the Alternating Fatigue Behavior of Unsaturated Polyester Resin

In this research, our concentration was directed to study the effect of weight fraction of the reinforcement materials (E-Glass) chopped strand laminates fibers, (E-Glass) continuous fibers and Glass powder, on the alternating bending fatigue behavior of the unsaturated polyester matrix (polymeric composite). The result of this study reveals that the variation of the weight fraction percentage of the reinforcement materials could affect the fatigue resistance of the produced composite. It has been noticed that the increase in the weight percentage fraction of both, glass laminates fibers (No. of laminates) and the glass continuous fibers, contributed effectively to improve the fatigue resistance, this reflects the longer fatigue life of the composites, that increase in the fatigue life could approach to more than hundred times, in the case of using glass laminate fibers and to more than twenty four times, in the case of using glass continuous fibers, at the same stress levels (9MPa), and the same percentage of weight fraction (6wt%). The result obtained of fatigue test in the case of using glass powder, suggests that the fatigue life depends on the percentage of weight fraction. The results also reveal an improvement in fatigue life three times longer for the weight fraction (2.5wt%), of glass powder, but the higher weight fraction (6wt%), reduced the fatigue life to a third compared to unreinforced base matrix.

Thermal degradation and fire behavior of thermoset resins modified with phosphorus containing styrene

In order to improve the fire behavior of unsaturated polyester resins (UPR) a phosphorus containing monomer, dimethyl-vinylbenzyl phosphonate (or S1), was used to replace a part of the reactive diluent (styrene). UPR with various phosphorus contents were prepared. Thermal degradation was studied using thermogravimetric analysis (TGA) and pyrolysis combustion flow microcalorimeter (PCFC), while fire behavior was investigated by cone calorimeter. The phosphorus yield in the residue was determined using energy-dispersive X-ray (EDX).TGA pointed out a decrease in thermal stability with increasing S1 content but also an important increase in char formation. Cone calorimetry highlighted pHRR decrease, and from 50% of styrene substitution a barrier effect was evidenced. Residue analysis enabled to determine the partition of phosphorus between vapor and condensed phase. It was shown that this partition depends on the degree of styrene substitution. At high S1 content, interactions between phosphonate groups enable a very efficient condensed phase action by creation of a charred protective barrier. This strategy was also successfully transposed to a vinyl ester resin (VER).

Investigation on mechanical and tribological behavior of naturally woven coconut sheath‐reinforced polymer composites

AbstractThe article presents the results of experimental investigation on mechanical and dry sliding wear behavior of unsaturated polyester resin (USP), reinforced with naturally woven coconut sheath and glass fibers. The mechanical properties of coconut sheath (N) and glass fiber (G) reinforced polyester composites were studied, and the tribological behaviors were tested on pin‐on‐disc sliding wear tester. Mass loss was determined as a function of sliding distance for a sliding velocity of 3.5 m/s and an applied normal load of 40 N. The experimental result revealed that the mechanical properties and wear resistance of the composites depend on the wt% reinforcement of coconut sheath/glass fiber and sliding distance. The hybrid reinforcement (GGN) greatly increased the mechanical properties of USP. At lower sliding distance, the N‐reinforced USP had lower wear loss, whereas at higher sliding distance, the hybrid fiber‐reinforced (GGN) USP composite had lower wear loss. Furthermore, the work showed that the higher sliding distance bring about changes in the worn surface features such as interface separation, inclined fracture of fibers, loss of matrix, and the appearance of debris with the two different fibers. The worn surfaces were also examined by scanning electron microscopy. The study showed differing trends with load for the two types of reinforcements. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Modeling and simulation of photofabrication processes using unsaturated polyester resins

AbstractSeveral kinetic models have been proposed to simulate thermosetting cure reactions. The most complex models, based on a mechanistic approach of cure reactions, are developed based on the concepts of free radical polymerization and the mechanism of reactions with diffusion. However, mechanistic models are usually quite impractical for engineering purposes because of the difficulty in obtaining the model parameters. An alternative to these mechanistic models are the phenomenological models, formulated in terms of the degree of cure and much easier to apply. Phenomenological models have been largely used to study thermal‐initiated cure reactions, although only few works used them to model the kinetics of ultraviolet‐initiated cure reaction. This work proposes a photo‐thermal‐kinetic model to study the behavior of unsaturated polyester resins during ultraviolet‐initiated cure reactions. The model considers samples with different amounts of initiator concentration and cure reactions performed under different ultraviolet light intensities. The model has been numerically solved using the finite element technique. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Modification of the Dynamic Damping Behavior of Unsaturated Polyester Resin

Unsaturated polyester resin is extensively used in the fiber reinforced composite industry and very often, their failure starts from the microcracking of the matrix resin. UPE resin, being a thermoset material, becomes very rigid after crosslinking and has poor energy absorption characteristics. To enhance its stress absorbing behavior in dynamic conditions, an attempt was made by blending it with SBR latex in three proportions (1, 5, and 10%). The three sets of samples were subjected to flexural testing and dynamic mechanical analysis. A 50% and 22% increase in modulus were observed in case of 1% and 5% latex added samples respectively. This indicates a strong intercomponent bonding in these samples. In the 10% latex added blend, the latex particles were evident as discrete phases in the continuous resin matrix. The flexurally fractured surfaces were examined under a scanning electron microscope. Their static and dynamic mechanical properties were correlated with their microstructure.

Synthesis and Characterization of Bismaleimide (1,3-bismaleimido benzene) – Vinyl Ester Oligomer Modified Unsaturated Polyester Interpenetrating Matrices

Bismaleimide - vinyl ester oligomer modified unsaturated polyester interpenetrating network systems were developed. Unsaturated polyester was modified with 10%, 20%, 30% (by wt) of vinyl ester oligomer with benzoyl peroxide as curing agents. The vinyl ester oligomer toughened unsaturated polyester matrix systems were further modified with 5%, 10% and 15% (by wt.) of 1,3-bismaleimido benzene. Thermal behaviour of the matrices were characterised by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and heat deflection temperature analysis. Mechanical properties were studied by ASTM methods. Data obtained from mechanical and thermal studies indicated that the introduction of vinyl ester oligomer into unsaturated polyester improves the fracture toughness with marginal reduction in the values of heat deflection temperature, and glass transition temperature. However, the introduction of BMI into VEO incorporated unsaturated polyester resin enhanced both thermal and mechanical behaviour of unsaturated polyester resin.

A Statistic Model of Mold Filling through Fibrous Structures

Ising’s model, incorporated with Monte Carlo simulation, is applied to the investigation of the mold filling processes. The behavior of a fluid flowing through fibrous structures is determined by both the fiber–fluid interaction within the system and the applied pressure. When the pressure is comparatively small, interaction within the system is found to dominate the flowing behavior, as shown in the behavior of water flowing through the PET fiber mat in the first part of the study. Then, when the applied pressure increases, it produces an effect that exceeds, little by little, that of the interaction within the system, and becomes dominant in determining the flowing behavior of the fluid. And this applies to the behavior of unsaturated polyester resin flowing through glass fiber-woven fabrics, as described in the second part of the study.

The effect of cure history on the fluorescence behavior of an unsaturated polyester resin with a fluorescence probe

Abstract: We have extensively characterized the fluorescence behavior of unsaturated polyester (UP) resin in the absence and presence of a 1,3-bis-(1-pyrenyl)propane (BPP) fluorescent probe at various dynamic and isothermal cure histories by means of a steady-state fluorescence technique using a front-face illumination equipment. In addition, we explored the effect of the fluorescence intensity on the relaxation of the fluorescent probe in the UP resin by resting the dynamically and isothermally cured resin at ambient temperature and pressure for 24 h. The monomer fluorescence intensity, which has two characteristic peaks at 376 and 396 nm, changed noticeably depending on the cure temperature and time and provided important information with respect to the molecular and photophysical responses upon curing. The result of the fluorescence study indicates that the increased local viscosity and restricted molecular mobility of the UP resin surrounding the BPP probe after curing are both responsible for the enhancement of the monomer fluorescence intensity. Our results also demonstrate that once the BPP probe has enough time to rearrange and become isolated prior to fluorescence, a sufficient amount of fluorescence is emitted. Therefore, we note that the fluorescence behavior of this UP resin system is influenced strongly by the relaxation process of the fluorescent probe in the resin as well as process used to cure the resin.

The effect of the addition of a low profile additive on the curing shrinkage of an unsaturated polyester resin

Composites made of glass fibers and unsaturated polyester resins are widely applied for various products. The failure processes of such composites are insufficiently understood. Fracture of the resin often initiates bulk composite fracture. Residual stresses occur during the curing of the resin due to the resin volumetric shrinkage. These unfavorable stresses may enhance resin fracture. Moreover, resin shrinkage may decrease the surface quality of the product. The addition of Low Profile Additives (LPA) to the resin may decrease or even remove these problems. The shrinkage behavior of unsaturated polyester resin with varying amounts of LPA is investigated in this work. The emphasis is on the development of curing shrinkage occurring after the gel point of the resin and on accompanying shirnkage stresses. These stresses can be reduced and even reversed by the addition of LPA.

Curing behavior of an unsaturated polyester system analyzed by Avrami equation

The isothermal cure behavior of an unsaturated polyester resin system is studied by differential scanning calorimetry. The reaction heats (at different curing temperatures) are presented and compared to the results of the previous studies. Various kinetic parameters as well as details of the curing process can be obtained and elucidated, based on the Avrami theory. The experimental results reveal that this analytical method is valid for describing the curing behavior of unsaturated polyester resins.