• Journal of the Korean Society of Safety
• /
• v.32 no.3
• /
• pp.1-7
• /
• 2017

Particle reinforced composites are materials that have enhanced physical properties by adding particle reinforcements to polymer materials and have been applied to a wide range of fields such as the aerospace, bio-technology and automative industry. In this study, particle reinforced composites were prepared by mixing $SiC/Al_2O_3$ to the vinyl ester as the thermoset resin. The purpose of this study is to evaluate mechanical properties and fracture behavior by the tensile test and single edge notch specimen according to the addition ratio of reinforcement. Addition of 1 and 2 wt% of the particle reinforcement to the vinyl-ester resin was effective for the strength improvement. However, when it was more than 3 wt%, its strength was decreased. Also the highest elastic modulus obtained as 3.19 GPa was found at the 2 wt% addition of reinforcement. Futhermore the fracture toughness was evaluated by the energy release rate and the maximum critical energy release rate was obtained when 1 wt% reinforcement. The results show that the limit of adding of $SiC/Al_2O_3$ for improvement of the mechanical and fracture performance is 2 wt% reinforcement particles.

• Polymer(Korea)
• /
• v.27 no.2
• /
• pp.120-128
• /
• 2003

The effects of catalyst, accelerator and blend composition on the cure behavior of unsaturated polyester resin (UPE), vinyl ester resin (VE) and their blends were studied using differential scanning calorimetry(DSC). The DSC thermograms strongly depend on each variable. The result shows that the small exothermic peak at 115$^{\circ}C$ is due mainly to the UPE component in the UPE/VE blends and the large one at 134~138 $^{\circ}C$ is due mainly to the VE component. The results also indicate that the change of the DSC thermogram measured after each blend was exposed to high temperature 18$0^{\circ}C$ and the fast curing conditions of a few tens seconds provide useful information on understanding the thermal processing of a blend at high speed. The measurements of resin flow time represent that there are three distinct stages of cure in the UPE/VE blends: induction, transition and macro-gelation stages, as similarly reported for UPE by others earlier. The thermal stability and flexural properties of the cured UPE are significantly improved by blending it with the VE, depending on the composition.

• Composites Research
• /
• v.35 no.6
• /
• pp.412-418
• /
• 2022

Flame-retardant vinyl ester (VE) resin films were developed from the mixtures of brominated and non-brominated epoxy resins via esterification with methacrylic acid without reactive diluents. The films were used to fabricate carbon fiber (CF) prepregs via a hot melt impregnation process. The viscosity of VE resins suitable for film production was optimized by mixing low-viscosity bisphenol-A and high-viscosity brominated bisphenol-A epoxy precursors. Increasing the bromine content of the cured VE resin further increased the limited oxygen index (LOI) (39%), storage modulus (2.4 GPa) at 25℃ and residual carbonization (16.1%) values compared to non-brominated VE. Manual layup of as-prepared VE prepregs with subsequent curing led to the successful fabrication of CF-reinforced composites with high tensile and flexural strength. The results from the study hold high promise for a styrene-free, environmentally friendly VE composite process in the future.

• Journal of Adhesion and Interface
• /
• v.19 no.1
• /
• pp.5-12
• /
• 2018

The purpose of this study is to evaluate the adhesive properties of polyurethane mixed aqueous dispersions by omitting the primer, dealing with the preparation of skins for synthetic leather with excellent adhesion by omitting the pre-treatment process. The two-component mixed polyurethane water dispersion was prepared by synthesizing an ester-based polyurethane resin (PU-T) and a carbonate-based polyurethane resin (PU-C) to obtain the final resin. As a result of measuring the peel strength of the adhesive specimens omitting the pre-treatment agent, it was confirmed that the state adhesive strength (ethylene vinyl acetate (middle): $4.2kg_f/cm$ and rubber (outsole): $4.4kg_f/cm$) there was. This makes it possible to omit the pre-treatment process which has been indispensably used in the shoe manufacturing process, thereby reducing the process time and reducing the amount of volatile organic compounds (VOCs) generated in the pre-treatment product, resulting in environmentally advantageous.

• International Journal of Aerospace System Engineering
• /
• v.4 no.1
• /
• pp.9-12
• /
• 2017

In this study, an investigation on mechanical properties of flax natural fiber composite is performed as a precedent study on the design of eco-friendly structure using flax natural fiber composite. The Vacuum Assisted Resin Transfer Molding-Light (VARTML) manufacturing method is adopted for manufacturing the flax fiber composite panel. The VARTML is a manufacturing process that the resin is injected into the dry layered-up fibers enclosed by a rigid mold tool under vacuum. In this work, the resin flow analysis of VARTM manufacturing method is performed. A series of flax composite panels are manufactured, and several kinds of specimens cut out from the panels are tested to obtain mechanical performance data. Based on this, structural design of chemical storage tank for agricultural vehicle was performed using flax/vinyl ester. After structural design and analysis, the resin flow analysis of VARTM manufacturing method was performed.

• International Journal of Aerospace System Engineering
• /
• v.1 no.1
• /
• pp.21-28
• /
• 2014

In this study, an investigation on mechanical properties of flax natural fiber composite is performed as a precedent study on the design of eco-friendly structure using flax natural fiber composite. The Vacuum Assisted Resin Transfer Molding-Light (VARTML) manufacturing method is adopted for manufacturing the flax fiber composite panel. The VARTML is a manufacturing process that the resin is injected into the dry layered -up fibers enclosed by a rigid mold tool under vacuum. In this work, the resin flow analysis of VARTM manufacturing method is performed. A series of flax composite panels are manufactured, and several kinds of specimens cut out from the panels are tested to obtain mechanical performance data. Based on this, structural design of chemical storage tank for agricultural vehicle was performed using flax/vinyl ester. After structural design and analysis, the resin flow analysis of VARTM manufacturing method was performed.

• Composites Research
• /
• v.28 no.2
• /
• pp.46-51
• /
• 2015

In this study, structural design and analysis of the automobile bonnet is performed. The flax/vinly ester composite material is applied for structural design. The Vacuum Assisted Resin Transfer Molding-Light (VARTML) manufacturing method is adopted for manufacturing the flax fiber composite bonnet. The VARTML is a manufacturing process that the resin is injected into the fly layered-up fibers enclosed by a rigid mold tool under vacuum. A series of flax/vinyl ester composite panels are manufactured, and several kinds of specimens cut out from the panels are tested to obtain mechanical performance data. Based on this, structural design of the automobile bonnet is performed.

• Composite Materials and Engineering
• /
• v.3 no.3
• /
• pp.167-178
• /
• 2021

In the present paper, the destructive behavior of distilled water, salty water, sulfuric acid, and heat on glass/vinyl ester composites was investigated by experimental methods. Hetron 922 vinyl ester resin and two types of mat and woven glass fibers as the reinforcements were used to fabricate composite test samples. All samples were immersed in distilled water, salty water, and sulfuric acid with three different concentrations. The tests were performed at 20℃ and 70℃ for the exposure duration of 1, 2, 4, and 8 weeks. Bending tests were performed after aging for all composite samples to check the degradation of the bending modulus and strength. The results show that the effect of distilled water, in comparison with salty water, on the degradation of composite samples was significant. On the other hand, almost non-sensitivity of concentrations of salty water on the weight gain of specimens has been observed. In addition, it was also observed that the degradation of samples at 70℃ temperature is much more than that of at 20℃. Also, it was observed that the flexural modulus of virgin specimens exposed to salty water (2% concentration) has been recovered just after two weeks of immersion. Furthermore, in some cases, composite samples under the sulfuric acid solution have lost almost 80% of their mechanical properties.

• Carbon letters
• /
• v.22
• /
• pp.101-104
• /
• 2017

• Journal of Aerospace System Engineering
• /
• v.10 no.3
• /
• pp.59-62
• /
• 2016

In this study, an investigation was performed on the mechanical properties of the natural-fiber-composite structure. The specimen was manufactured using the Vacuum Assisted Resin Transfer Molding (VARTM) method. The flax-fiber materials were adopted for the natural fiber composite, and vinyl-ester resin was also adopted. After a manufactured specimen was obtained, a mechanical test was carried out. The mechanical properties of the experiment results were compared with those of the natural-composite data cited from a number of other references.