• Polymer(Korea)
• /
• v.29 no.2
• /
• pp.161-165
• /
• 2005

$\alpha,\omega-Vinyl$ poly(dimethyl-methylphenyl) siloxane propelymer (VPMPS ) was prepared by the equilibrium polymerization of octamethylcyclotetrasiloxane $(D_4)$, 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane $(D_3^{MePh})$, and 1,1,3,3-tetramethyl-1,3-divinylsiloxane (MVS) as end-blocker. And also, $\alpha,\omega-hydrogen$ poly(dimethyl-methyltrifluoropropyl)siloxane prepolymer (HPDMFS) was prepared from $D_4$, 1,3,5-trimethyl-1,3.5-trifluoropropylcyclotrisiloxane $(D_3^{MeF3P})$, and 1,1,3,3-tetramethyldisiloxane. Poly(organosiloxane) rubber composite containing high thermal conductive filler was prepared by compounding VPMPS, HPDMFS, spherical alumina, and catalyst in high speed dissolver. The crosslinking density of poly (organosiloxane) composite was measured by oscillation rheometer. Poly(organosiloxane) composites of TC-POXR-2 and TC-POXR-4 prepared by controlling average diameters of thermal conductive filler, spherical alumina according to Horsfield's packing model were shown to 1.13 W/mK for TC-POXR-2 and 1.19 W/mK for TC-POXR-4.

• Polymer(Korea)
• /
• v.35 no.4
• /
• pp.342-349
• /
• 2011

The effect of the amount of vinyltriethoxysilane (VTEOS) in precipitated silica filled silicone rubbers was extensively investigated in terms of the change of mechanical properties, heat resistance, oil resistance, compression set, resilience, and curing characteristics. As the content of VTEOS increased from 0 to 2.0 phr, the hardness of the silicone rubber increased, however, tensile strength, elongation at break, and tear strength decreased. From heat resistance test, the change of mechanical properties was pronounced for silicone rubber treated with more VTOES. The best heat resistance was achieved at 2.0 phr VTOES. In addition, oil resistance was proportionally improved with VTEOS content. From oil resistance test. it was found that the decrease in hardness and maximum elongation was reduced for VTEOS-added systems. Finally, resilience, compression set, degree of cure and crosslink density were significantly enhanced with the amount of VTEOS.

• Elastomers and Composites
• /
• v.49 no.2
• /
• pp.117-126
• /
• 2014

Methylene diisocyanate (MDI) was investigated as a novel interfacial modifier to enhance the performances of poly(methyl methacrylate)-modified starch/styrene-butadiene rubber (PMMA-modified starch/SBR) composites. Owing to the formation urethane linkage on one side and ${\pi}-{\pi}$ adhesion on the other side, MDI acted as an intermediated linkage role in the PMMA-modified starch/SBR interfaces, which was evidenced by the morphological, mechanical, dynamic mechanical and thermal decomposition studies. As a result, the presence of MDI significantly improved the mechanical properties and thermal stability of PMMA-modified starch/SBR composites. In addition, the effect of starch concentration on the various performances of the resulted MDI/PMMA-modified starch/SBR composites, such as morphology, vulcanization characteristics, mechanical properties, toluene swelling behavior, and thermal stability were investigated and discussed in detail. The obtained MDI/PMMA-modified starch/SBR composites exhibited superior mechanical properties to carbon black/SBR (CB/SBR) composites, demonstrating the potential use of the renewable starch as a substitute for CB in the rubber compounds.

• Elastomers and Composites
• /
• v.56 no.4
• /
• pp.243-249
• /
• 2021

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, we investigated the effect of varying the content of butadiene rubber (BR) on the properties of the rubber compounds and the amount of particulate matter in the TBR tire tread compound. Furthermore, we utilized carbon black in the NR/BR blend compounds owing to its excellent compatibility, and we used silica in the ENR-25/BR blend compounds because it can interact chemically with epoxide groups. The NR/BR blend compounds and the ENR-25/BR blend compounds were evaluated by varying their BR content between 20 phr and 30 phr. The results showed that the ENR-25/BR blend compounds had superior wear resistance than the NR/BR blend compounds. This was caused by the interaction between silica and ENR. In addition, it was confirmed that the increased wear resistance as the BR content increased. Furthermore, compared to the NR/BR blend compounds, ENR-25/BR blend compounds exhibited a lower tan 𝛿 value at 60℃ because silica was used as filler. This indicates a higher fuel efficiency. The measurement results for wear particulate matter showed that as increasing the BR content resulted in generation of less wear particulate matter. This was caused by the increased wear resistance. Moreover, the ENR-25/BR blend compounds with excellent filler-rubber interaction exhibited lower quantities of generated wear particulate matters as compared to the NR/BR blend compounds.

• Elastomers and Composites
• /
• v.59 no.2
• /
• pp.64-72
• /
• 2024

As air pollution continues to increase owing to increasing traffic centered in urban areas, the tire industry is researching methods to reduce particulate matter. In this study, functionalized lithium butadiene rubber (F-LiBR) was applied to a natural rubber (NR)/butadiene rubber (BR) blend compound often used in truck bus radial (TBR) tire treads. The effect of the functional group that can react with carbon black (CB) in BR was investigated in terms of the dispersion of CB and the compound performance, including the generation of particulate matter. Compounds that were substituted with F-LiBR exhibited enhanced interaction with CB, resulting in excellent filler dispersion. Although F-LiBR exhibited lower crosslinking density and inferior abrasion resistance due to its high vinyl content, the compound with 30 phr of F-LiBR was advantageous in terms of its rolling resistance due to the excellent filler dispersion, which was also effective in reducing the amount of generated particulate matter (up to 56% reduction for PM_2.5, and 67% reduction for PM₁₀). The results confirmed the benefits of the introduction of functional groups into TBR tire tread compounds, which can aid in improving the fuel efficiency and reducing particulate matter generation.

• The Journal of Korean Academy of Prosthodontics
• /
• v.30 no.2
• /
• pp.233-245
• /
• 1992

The purpose of this study was to evaluate the demensioal stability and wettability of several rubber impression materials. Impressions were made from a metal master die machined to stimulate five full veneer crown preparations symmetrically placed in an arch form. Cast from impressions were measured about ; 1) intrapreparation distance 2) lower base diameter 3) length. For comparing materials were formed against a smooth surface. The advancing contact angle of a saturated aqueous solution of $CaSO_4$ on the impression materials was measured after 1 minute. Mean contact angle were calculated and results were analyzed. Results were as follows : 1. As the intrapreparation distance, hydrophilic addition-cured silicone had the smallest change and condensation-cured silicone had the largest one. 2. As the lower base diameter, traditional addition-cured silicone had the smallest change and polyether had the largest one. 3. As the height, traditional addition-cured silicone had the smallest change and polyether had the largest one. 4. As the contact angle, polyether had the smallest change and condensation-cured silicone had the largest one.

• The Journal of Korean Academy of Prosthodontics
• /
• v.27 no.2
• /
• pp.249-259
• /
• 1989

Dental impression materials often become contaminated with patients' saliva and blood which creates the potential for cross-infection. It was the purpose of this study to investigate the effects of disinfection of three different rubber impression materials with four different disinfecting solutions. Polysulfide, vinyl polysiloxane and polyether impression materials were mixed according to the manufacturer's directions and samples were formed on a stainless steel model. On removal from the standard model, impressions were immersed in a disinfectant (acid-potentiated glutaraldehyde, phenollic compound, chlorine compound, iodophor) at room tempera tures for ten minutes. After disinfection, the distance between reference points(linear dimension) was measured using the non-contact automatic cordinate measuring projector(MZ-1, Nikon). Through statistical analyses on the data from this study,. the following conclusions were obtained. 1. Polysulfide, vinyl polysiloxane impressions were disinfected without dimensional change.(p>0.05) 2. Polyether impressions which were immersed in acid-potentiated glutaraldehyde were statistically different from control group.(p<0.05) But the amount of shrinkage(0.04%) would not be clinically significant. 3. By immersion of polysulfide, vinyl polysiloxane, polyether impressions in Banicide, Biocide, Multicide plus, sodium hypochlorite for ten minutes, clinically accurate impressions were obtained without dimensional change.

• Tribology and Lubricants
• /
• v.33 no.1
• /
• pp.31-35
• /
• 2017

Recently, international attention has been focused on the development of non-traditional energy resources such as shale gas and oil sands, due to the steep increase in the demand for natural resources. The materials incorporated in an oil gas plant module experience extreme environments, and are prone to various problem such as fracture, corrosion and abrasion due to low-temperature brittleness. In order to improve the plant life, it is necessary to perform characteristics study and performance evaluation of the materials. In particular, this paper explains the main set of materials which are most frequently used in oil sands plant project. In order to investigate wear characteristics, the authors carried out abrasive wear tests of TP 316, stainless steel and SS 400, structural rolled steel. For the analysis of the abrasive wear resistance of an oil sands plant, the authors carried out the test according to ASTM G 105 "Standard Test Method for Conducting Wet Sand/Rubber Wheel Abrasion Test" standard guidelines. The authors have derived the results from the data associated with the loss of mass with respect to wear rate. During the test, for a given wear length for 10,000 revolutions, the rotational speed and applied force of the rubber wheel were varied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.495-496
• /
• 2008

This paper describes the influence of Ultra-violet irradiation on time to tracking resistance of epoxy insulating materials by use of the inclined plane test. And, the influence of surface degradation was evaluated through several method such as measurement of contact angle, surface roughness, using a scanning electron microscopy. As the 1000 hours of the surface degradation with UV-CON, the flashover time decreases at different rates depending on epoxy resin and silicone rubber specimen. As the duration of the surface degradation with UV-CON is prolonged, the contact angle of epoxy resin decreases at the rate of degradation time, while that of silicone rubber was not exchanged. It is assumed that this phenomenon is related to the decrease in hydrophobicity of the surface of the materials. Also, as to epoxy resin, the decrease of hydrophobicity due to surface degradation with UV-CON is greater than that resulting from surface degradation with WOM. The UV radiation produced chalking and crazing on the surface of the insulating materials specimen.

• Elastomers and Composites
• /
• v.45 no.4
• /
• pp.245-249
• /
• 2010

Much interest on the thermoplastic elastomers (TPEs) has recently been attracted in commercial fields as well as scientific and applied research. The TPEs have their own characteristic area especially in relation with block copolymers as well as many other polymeric materials, since they show interesting features displayed by the conventional vulcanized rubber, and at the same time, by the thermoplastics. In addition, they are characterized by a set of interesting properties inherent to block and graft copolymers, variety of blends and vulcanized materials. The importance of TPE as organic materials can be evaluated by the number of published reports (papers, patents, technical reports, etc). For the suitable introduction of the TPE, historic, scientific, technical and commercial considerations should be taken into account. This review article starts with a brief discussion on historical considerations, followed by a introduction of the main preparations and analytical techniques utilized in chemical, structural, and morphological studies. The properties, processing tools, the position among organic materials, and applications of TPEs are also briefly reviewed. Finally, the most probable trends of their future development are discussed in a short final remarks.