• Journal of the Korean Wood Science and Technology
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• v.26 no.1
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• pp.70-75
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• 1998

In this paper, the relationships between volumetric mixing ratio of rubber chip and physical and mechanical properties of wood/rubber composite panel was examined in order to investigate the mixture characteristics of wood and rubber chip. Because of the specific gravity of rubber differed from wood chip, physical properties of wood/rubber composite panel was shown very different values by mixing rate of chip element. Specific gravity in air-dry of composite panel was increased rapidly as volumetric percent of rubber chip was increased. Moisture content of composite panel was decreased as volumetric percent of rubber chip element was increased. This results was considered that wood weight is light and porosity material for moisture absorption. Compressive strength and modulus of rupture in bending test were decreased as volumetric percent of rubber chip increased. By mixing ratio control of chip elements, various wood/rubber composite panel can be applicable to every interior materials such as subfloor, playground, and exterior materials such as road blocks for recreational facilities in garden and forest and city parks.

• Journal of the Korean Wood Science and Technology
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• v.25 no.4
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• pp.29-38
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• 1997

The effect and control of wood property of reconstituted composite panels for improved board properties by wood-waste materials and development of combination method for heterogeneous materials have been of interest to the wood science researchers. The purpose of this study is to consider the properties in relation to hot pressing conditions and to develope the optimum hot pressing condition with waste wood and waste tire for the manufacturing of composite boards. The study of composite boards for recycling of wood and waste tire is nothing up to the present. Physical and mechanical properties such as specific gravity, moisture content, swelling coefficient, modulus of rupture and modulus of elasticity in bending test were studied. The condition of 3-stage press time for the lowest moisture content of composite board was $4{\rightarrow}3{\rightarrow}3$ minutes. Specific gravity of composite panels was affected mainly by the amount of rubber chip. Because of the low rigidity and high elasticity in rubber chip, it is considered the composite panel was adequate material in the place of compression load, but not bending load. Therefore, it was concluded that a use of rubber-based wood composite panel is proper to the interior materials such as floor a room than exterior materials. From the test results, the most optimum hot pressing conditions were $4{\rightarrow}3{\rightarrow}3$ minutes for 3-stage press time and $45{\rightarrow}20{\rightarrow}5kg/cm^2$ for 3-stage press pressure. The rubber-based wood composite panel was very excellent in elasticity by combination of rubber chip in comparison with existing other wood-based materials. Therefore, it was considered that rubber-based wood composites can be applicable to every interior materials such as floor a room and will be expected to effective reuse and recycle of waste tires and wood-waste materials, and will be contribute to protection of environment pollution in earth.

• Elastomers and Composites
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• v.29 no.5
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• pp.436-443
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• 1994

Melamine resin was mixed with polybutadiene rubber or wood flour in the ranges of $5{\sim}75%(wt.%)$. For mixtures, physical and thermal properties were tested experimentally. Physical properties were mainly influenced on the dispersed states of rubber or wood flour. The highest flexural and impact strength were obtained at wood flour content $65{\times}67%$. Rubber was homopolymerized by hardner, or partially copolymerized with melamine resin. At rubber content $3{\sim}6%$, cured products represented lower modulus without decreasing mechanical strength.

• Journal of the Korean Wood Science and Technology
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• v.42 no.5
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• pp.605-614
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• 2014

This study investigated microstructural changes of cured urea-formaldehyde (UF) resins mixed with aqueous rubber latex emulsion after intentional acid etching. Transmission electron microscopy (TEM) was used in order to better understand a hydrolytic degradation process of cured UF resins responsible for the formaldehyde emission from wood-based composite panels. A liquid UF resin with a formaldehyde to urea (F/U) molar ratio 1.0 was mixed with a rubber latex emulsion at three different mixing mass ratios (UF resin to latex = 30:70, 50:50, and 70:30). The rate of curing of the liquid modified UF resins decreased with an increase of the rubber latex proportion as determined by differential scanning calorimetry (DSC) measurement. Ultrathin sections of modified and cured UF resin films were exposed to hydrochloric acid etching in order to mimic a certain hydrolytic degradation. TEM observation showed spherical particles and various cavities in the cured UF resins after the acid etching, indicating that the acid etching had hydrolytically degraded some part of the cured UF resin by acid hydrolysis, also showing spherical particles of cured UF resin dispersed in the latex matrix. These results suggested that spherical structures of cured UF resin might play an important role in hindering the hydrolysis degradation of cured UF resin.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.527-530
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• 2007

The binary liquid type fire retardant paint of polyurethane (alkyd resin) lacquer is developed to cover the defect of one liquid type white paint of chlorinated rubber used generally but which has weak surface and poor adhesive strength to the wood as well as generating much black smoke when it is firing. The properties of the composition of binary liquid type of white paint of polyurethane lacquer developed in this study for using to wood has shown that the better suppressed smoke generation and enhanced the adhesive strength to the wood than that of fire retardant white paint used.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.38-45
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• 2005

This research was investigated on the increase in strength capacity among different five wood-to-wood connections. Group using small diameter bolts with equal area loss has the highest increase in strength capacity, secondly the group inserted plywood, thirdly the group used glued bolt, and lastly the group inserted rubber plate. These groups showed at least 10% increase in strength capacity more than existing connection groups. Therefore, these results can be applied to develop the new highly efficient connection. To select suitable connection configuration and materials, however, economical advantage and increase in strength capacity and the difficulty should be considered by the additional works.

• Journal of Environmental Science International
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• v.14 no.6
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• pp.521-524
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• 2005

We introduce a simplified crossing wood drain disperses rain water concentration and is used to protect the road surface from erosion due to flooding over the unpaved road. The efficiency of a simplified crossing wood drain was also investigated. A structure of simplified crossing wood drain can be produced within 10 minutes and installed within 18 minutes. The cost of the this product is 1/5 of that of the existing crossing drain product. The production and installation cost can be reduced according to dexterity. In the context of such applications, the degrees of damage for a rubber pad, which preventing the rain overflow, were varied according to their materials. A type of 8.2mm thick fabric rubber was the most suitable in this study.

• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.164-169
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• 1998

Vulcanized rubber containing three kinds of oligomeric resins such as cashew resin, t-octylphenol formaldehyde resin and terpene modified wood rosin has been characterized by simultaneous pyrolysis methylation-gas chromatography/mass spectrometry (SPM-GC/MS). After methylation by the SPM method using tetramethylammonium hydroxide, the methylated pyrolyzates of the corresponding resins were detected with higher sensitivity than underivatized pyrolyzates without any interferences from other ingredients of vulcanized rubber.

• Safety and Health at Work
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• v.5 no.2
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• pp.86-90
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• 2014

Background: Urinary 1-hydroxypyrene (1-OHP) was selected as a biomarker of polycyclic aromatic hydrocarbons (PAHs) to explore the accumulation level in the bodies of workers at rubber smoke sheet factories in southern Thailand. Methods: Spot urine samples were taken from four groups of workers from June 2006 to November 2007. The nonexposure or control groups included habitual cigarette smokers and nonsmokers. The other two groups were workers exposed to particle-bound PAHs from rubber wood smoke and they were nonsmokers. All spot urine samples were analyzed for 1-OHP and creatinine levels. Results: The mean${\pm}$standard deviation urinary 1-OHP in the control group of habitual smokers and the nonsmokers was $0.24{\pm}0.16{\mu}mol/mol$ creatinine and not-detected to $0.14{\mu}mol/mol$ creatinine, respectively. In the workers, the 1-OHP levels on workdays had no significant difference from the 1-OHP levels on the days off. The yearly average 1-OHP level was $0.76{\pm}0.41{\mu}mol/mol$ creatinine whereas the average 1-OHP level during 10 consecutive workdays was $1.06{\pm}0.29{\mu}mol/mol$ creatinine (p > 0.05). Conclusion: The urinary 1-OHP levels of workers exposed to PAHs were high. The accumulation of 1-OHP in the body was not clear although the workers had long working hours with few days off during their working experience. Therefore, a regular day off schedule and rotation shift work during high productive RSS should be set for RSS workers.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.66-71
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• 2015

Safety, resilience and comfort of pedestrian were assessed by the British Pendulum Test and SB/GB factor test at 8 kinds of sidewalk pavement. Sidewalk paving materials were normal concrete, porous concrete, concrete block, soil concrete, asphalt, rubber chip/resin mixture, wood chip/resin mixture and floor tile. In addition, a survey was conducted to investigate the perception of pedestrians on the sidewalk paving material. As a result, while the skid resistance value was measured in the most 60BPN above, the floor tile showed a low value of about 30BPN. The ratios of SB factor to GB factor of the elastic pavements(rubber/resin mixture and wood chip/resin mixture) appeared to be relatively large when compared with those of the conventional sidewalks. The survey showed that respondents perceived as more safe and comfortable elastic pavements compared to conventional pavements. Approximately 50% of respondents answered that hardened soil pavement was the most environmentally friendly.