• Elastomers and Composites
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• v.38 no.3
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• pp.227-234
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• 2003

Silicone composites for high voltage insulator (HVI SC) were prepared by adding aluminum trihydrate(ATH) treated by surface treatment agent to base silicone compound at the ratio oi 100:20, 100:40, 100:60, 100:80, and 100:100, respectively And also, ATH was treated by various surface treatment agents, such as stearic arid, acryl silane, and vinyl silane under compounding process. Mechanical properties and electrical properties were investigated for the various contents of ATH and surface-treatment agents. Mechanical properties such as tensile strength, elongation, and tear strength decreased as the load of ATH increased. Volume resistivity, AC break down strength, and tracking resistance for HVI SC containing ATH treated by vinyl silane were better than those for HVI SC containing ATH treated by other surface treatment agents, such as stearic acid and acryl silane. Polymer-filler interaction of silicone composites according to surface treatment agents was studied by measuring bound rubber contend(BR). From the experimental results, BR of silicone composite containing ATH treated with vinyl silane was higher than that of the others. The degree of rule for silicone composite was investigated using Rheometer. Maximum torque of silicone composites contaning ATH treated with vinyl silane was higher than that of silicone composite contaning ATH treated with other surface agents.

• Journal of Pharmacopuncture
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• v.13 no.3
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• pp.47-62
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• 2010

Objectives: Colitis is an inflammatory bowel disease characterized by colonic mucosal inflammation and chronic relapsing events represents. The purpose of this study is to evaluate effects of pharmacopuncture of anti-inflammatory herbal compound (AiC) applied to the different acupoints in the acute colitis induced by trinitrobenzenesulphonic acid (TNBS) intracolonic injection in rats. Methods: In Male Sprague - Dawley rats, weighing 250~400g, TNBS (5 mg/kg) was infused intrarectally through a silicon rubber catheter into the anus under isoflurane anaesthesia. Acupoints of LI4 (Hapkok), ST25 (Cheonchu), ST36 (Joksamni), and BL25 (Daejangsu) were intramuscularly injected by AiC, respectively (injection volume & times: 0.2 ml / acupoint, twice times on the 2nd & 3rd day). Expressions of cFos protein in the periaqueductal gray (PAG), locus coeruleus (LC), nucleus of solitary tract (Sol), and the 6th lumbar spinal cord (L6 s.c.) were observed at 24 hr after TNBS induced colitis by immunohistochemistry. Results: The expression of c-Fos protein in the L6 s.c., Sol, LC and PAG increased 24 hr after TNBS injection into colorectum as compared to normal and 50% ethanol treated group. AiC to LI4 inhibited the expression of c-Fos protein in Sol and PAG but not L6 s.c. and LC. AiC to ST36 showed significant inhibition the c-Fos expression in L6 s.c., Sol and PAG. AiC to ST25 only showed the effects in L6 s.c. and PAG. AiC to BL25 inhibited significantly the expression of c-Fos protein all over the areas. To investigate whether or not endogenous opioids are involved, intrathecal injection of naltrexone (30ug/30ul) was applied before the 2nd pharmacopuncture treatment 24 hr after TNBS-induced colitis in rat. Naltrexone reversed the inhibition of c-Fos protein expression in the spinal cord and brainstem. Conclusions: These data show that pharmacopuncture of Aic potently inhibits signal pathways ascending hypersensitivity of colorectum after TNBS induced colitis and depends on the endogenous opioids according to acupoints.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.310-316
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• 2020

Terpene-modified phenolic resins were used to improve the tires wet traction related to the driving safety and also rolling resistance related to fuel efficiency. In this work, alpha-pinene, beta pinene, and delta limonene resins, which constitute different basic structures of terpene-modified phenolic resins, were individually added to the tread compounds of tires and their physical properties were compared with those of the alkyl phenol resin compounds. Alkyl phenolic resins showed no significant difference in tangent delta from terpene-modified phenolic resins at 0 ℃, which is related to wet traction, but showed higher tangent delta at 80 ℃, which is related to rolling resistance, indicating smaller fuel efficiency improvement effects. Among the terpene-modified phenolic resins, beta pinene one showed improved wet traction and fuel efficiency compared to those of other resins. Delta limonene resin showed the best wet traction improvement effect, and alkyl phenolic resins showed relatively high tensile strength and abrasion property. All terpene-modified resins exhibited better rolling resistance than those of alkyl phenolic ones so that they can be said to have better fuel efficiency improvement effects and also to improve other properties compared to those of blanks. Terpene-modified phenolic resins could be used when mixing tire compounds referring to the properties of the phenolic resins revealed in this work, which could result in preparing compounds with improved wet traction and rolling resistance.

• Elastomers and Composites
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• v.39 no.2
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• pp.131-141
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• 2004

The recycling of waste XLPE(crosslinked polyethylene), which is a major source of scraps from high voltage power transmission cables, has been discussed. The waste XLPE scraps were ground into fine powder with various sizes from less than $100{\mu}m$ up to about $1000{\mu}m$ using two types of tailor-made pulverizers. The compounds were prepared in a modular intermeshing co-rotating twin screw extruder at various conditions such as different compositions, types and powder sizes of waste XLPE, screw configurations and various polymer matrices (LDPE, HDPE, PP, PS). The mechanical and rheological properties and the fracture surface or the compounds were investigated. It was found that an improved impact strength was obtained from the compound with white XLPE powder pulverized from the scraps without outer/inner semi-conductive layers. Generally, the impact strength increases with the content of XLPE but decreases with the size of XLPE. Especially for LDPE, the extrusion was possible up to 80 wt% loading of XLPE. Also, the impact strength increases with the number of kneading disc blocks in the given screw configurations. The melt viscosity of the compounds increases with increasing XLPE loading. However, the higher shear thinning behavior of the compounds at common shear rates implies proper processibility of the compounds. In addition, the impact strength for other polymer matrices used increases with XLPE and it is noticeable that the impact strength of PS/XLPE (80/20 wt%) compound was improved twice that of pure PS.

• Elastomers and Composites
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• v.43 no.3
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• pp.183-190
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• 2008

In this study, we have investigated mechanical properties and scratch resistance of polypropylene compounds by two types of masterbatch with different molecular weight of PP. Masterbatches were prepared with polypropylene(PP) and polydimethylsiloxane(PDMS) by melt mixing. Mechanical properties and scratch behavior were examined with UTM and polarizing microscope. The morphology surface of grain pattern was investigated Color 3D Laser Scanning Microscope. Mechanical properties of two masterbatches containing PP compounds showed a little bit difference in accordance with amount of M/B. Scratch resistance was much improved by adding masterbatches used high-molecular weight PP. Scratch resistance was excellent when grain pattern of the surface is deep, large, round and irregular.

• Elastomers and Composites
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• v.38 no.4
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• pp.342-353
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• 2003

This work is about the development of jet-fuel resistant PVC sealant using a polyester plasticizer. PVC copolymer was compounded with adipic acid glycol(Songcizer P-3000) or DOP plasticizers. Fuel-immersed and non-immersed penetration, solubility, flow, and elongation by tensile adhesion of PVC compounds were measured. Penetration increase by fuel immersion and solubility of PVC compounds with adipic acid glycol polyester plasticizer were smaller than those of PVC compounds with DOP plasticizer. Elongation by tensile adhesion test of PVC compound containing 500 phr of Songcizer P-3000 decreased proportionally to the content of DCDP (dicyclopentadiene) base petroleum resin adhesion promoter. Calcium carbonate($CaCO_3$) filler inhibited the diffusion of fuel in all the PVC compounds and decreased the solubility of PVC compounds containing Songcizer P-3000.

• Elastomers and Composites
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• v.22 no.3
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• pp.195-203
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• 1987

In this study, as one of the developing ways of the functional elastomer, improvement of the functionality of CB-BR was attempted through moisture curing reaction. The curing reaction of CB-BR was determined with an use of 3-aminopropyltriethoxysilane(APS) as a crosslinking agent, also a solution reaction with an active chlorine of CB-BR was elucidated by using a reaction kinetics theory and a study of physical property was made through moisture curing on the compound of 3-aminopropyltriethoxysilane and CB-BR The results of this study obtained are as follows : 1) CB-BR reacted easily with APS in the liquid state and the reaction rate coefficient and activation energy were as follows : 2) Optimum pressure condition of moisture cured elastomer(CB-BR+APS) was 20 minutes at $150^{\circ}C$, and the crosslinked elastomer was close to the theoretical value (q=1) for Flory's equation($\frac{\alpha}{\alpha-1}=q{\nu}RT$)

• Elastomers and Composites
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• v.47 no.3
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• pp.231-237
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• 2012

This study measured the mechanical and damping properties of EPDM compounds including fillers. Semi-reinforcing furnace black (SRF), high abrasion furnace black (HAF) and acetylene black were used as fillers. Dicumyl peroxide (DCP) were used as curing agents. The measurements were conducted using a moving die rheometer (MDR), durometer, universal testing machine (UTM), compression set and dynamic mechanical analysis (DMA). The tensile strength and elongation at break increased with increasing SRF contents in EPDM compounds. However, they decreased with increasing the amount of acetylene black. In the inspecting temperature range, EPDM compound filled acetylene black had stable storage modulus. Furthermore, the tan ${\delta}$ of the EPDM compounds obtained was enhanced by compounding with acetylene black.

• Elastomers and Composites
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• v.44 no.3
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• pp.290-298
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• 2009

In this paper, the Fe-activated carbon fiber (ACF)/$TiO_2$ composite catalysts were prepared by a sol-gel method. The synthesized photocatalysts were used for the photo degradation of Methylene blue solution under UV light. From Brunauer-Emmett-Teller measurements (BET) data, it was shown the blocking of the micropores on the surface of ACF by treatment of Fe and Ti compound. As shown in SEM images, the ferric compounds and titanium dioxides were fixed onto the ACF surfaces. The result of X-ray powder diffraction showed that the crystal phase contained a mixing anatase and rutile structure and the 'FeO+$TiO_2$' from the composites. The EDX spectra for the elemental analysis showed the presence of C, O, and Ti with Fe peaks. Degradation activity of MB could be attributed to +OH radicals derived from electron/hole pair's reactions due to photolysis of $TiO_2$ and photo-Fenton effect of Fe.

• Elastomers and Composites
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• v.59 no.2
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• pp.73-81
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• 2024

In the field of electronic components, the potting material, which is a part of the electronic circuit package, plays a significant role in protecting circuits from the external environment and reducing signal interference among electronic devices during operation. This significantly affects the reliability of the components. Therefore, the accurate prediction and assessment of the lifespan of a material are of paramount importance in the electronics industry. We conducted an accelerated thermal aging evaluation using the Arrhenius technique on elastic potting material developed in-house, focusing on its insulation, waterproofing, and contraction properties. Through a comprehensive analysis of these properties and their interrelations, we confirmed the primary factors influencing molding material failure, as increased hardness is related to aggregation, adhesion, and post-hardening or thermal-aging-induced contraction. Furthermore, when plotting failure times against temperature, we observed that the hardness, adhesive strength, and water absorption rate were the predominant factors up to 120 ℃. Beyond this temperature, the tensile properties were the primary contributing factors. In contrast, the dielectric constant and loss tangent, which are vital for reducing signal interference in electric devices, exhibited positive changes(decreases) with aging and could be excluded as failure factors. Our findings establish valuable correlations between physical properties and techniques for the accurate prediction of failure time, with broad implications for future product lifespans. This study is particularly advantageous for advancing elastic potting materials to satisfy the stringent requirements of reliable environments.