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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Elastomers and Composites
Journal Basic Information
Journal DOI :
The Rubber Society of Korea
Editor in Chief :
Volume & Issues
Volume 44, Issue 4 - Dec 2009
Volume 44, Issue 3 - Sep 2009
Volume 44, Issue 2 - Jun 2009
Volume 44, Issue 1 - Mar 2009
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An Investigation of Surface Appearance of an Injection-Molded Plastic Part with Various Induction Heating Conditions
Sohn, Dong-Hwi ; Seo, Young-Soo ; Park, Keun ; Lee, Kwang-Woo ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 358~365
High-frequency induction is an efficient way to rapidly heat mold surface by electromagnetic induction. In the present work, high-frequency induction heating is applied to injection molding of a mobile phone cover in order to eliminate weldlines by efficiently raising the mold temperature. Through the induction heating experiments, the maximum temperature of
is obtained on the mold surface in 3s of heating, which is higher than the glass transition temperature of the resin material. An injection molding experiment is then performed with the aid of induction heating, from which we can successfully remove all the weldlines of the mobile phone cover. The effect of induction heating conditions such as the heating power and the heating time on the surface appearance is experimentally investigated.
Improvement of Assembly Characteristics of a Lens Module in a Mobile Phone Camera using Finite Element Analysis
Moon, Yang-Ho ; Moon, Jae-Ho ; Lyu, Min-Young ; Park, Keun ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 366~372
The present study covers the optimal design for a lens module in a mobile phone camera by using the design of experiments (DOE) and finite element (FE) analysis. FE analyses are performed to investigate the effect of design parameters on the amount of torque required to assemble a barrel and a housing part. The DOE approach is then performed to optimize the design parameters in order to maintain an appropriate torque with less variations.
A Study on the Warpage in Injection Molded Part for Various Part Designs and Non Reinforced Resins
Lee, M. ; Kim, J.H. ; Park, S.R. ; Lyu, M.Y. ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 373~377
Most of the plastics products are being manufactured by injection molding. Warpage in injection molded affects the product dimension and it causes assembling problem. In this study, warpages in the injection molded part been studied. Specimens are rectangular flat shapes with and without ribs. Amorphous polymers (PC and ABS) and crystalline polymers (PP and PA66) were used for material. Flat shape with ribs showed higher warpage than flat shape without ribs by 6 to 9%. The specimens with ribs that are located parallel to the flow direction has higher warpage than specimens with ribs that are located perpendicular to the flow direction by 25 to 39%. Crystalline polymers have higher warpage than amorphous polymers by 23 to 67%. Warpage decreases as packing time increases and it increases as injection temperature increases.
Forming Analysis of L-type Bending of Sandwich Sheet with Pyramid Core
Lim, Sung-Jin ; Chung, Wan-Jin ; Kim, Jong-Ho ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 378~383
In this study, the use of a condensed model is proposed for the simulation of forming of sandwich sheet with pyramid core. A corresponding finite element analysis for L-type bending is carried out to prove the accuracy and the effectiveness. In order to improve the accuracy of forming analysis, more precise modeling of core shape and consideration of work-hardening of previous core forming are carried out. Simulation results are compared with those of experiment. Deformation shape and post-buckling behavior by simulation are in good agreement with those of experiment for the considerable range of deformation. From the comparison of force-displacement curve, it is shown that the proposed model shows good prediction of post-buckling behavior.
An Analysis of Formability of Micro Pattern Forming on the Thin Sheet Metal
Cha, Sung-Hoon ; Shin, Myung-Soo ; Kim, Jong-Ho ; Lee, Hye-Jin ; Kim, Jong-Bong ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 384~390
Roll-to-roll forming process is one of important metal processing technology because the process is simple and economical. These days, with these merits, roll-to-roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate. The solar cell plate may have millions of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll-to-roll forming process. Also formability is analysed for various number of mesh, protrusion shapes and forming temperature.
Thread Rolling Analysis for Lead Screw Process Design
Shin, Myoung-Soo ; Cha, Sung-Hoon ; Kim, Jong-Bong ; Kim, Jong-Ho ; Ra, Seung-Woo ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 391~396
This paper presents the numerical analysis of thread rolling. Firstly, the analysis is focused on the effective analysis conditions that guarantee the reliability of the analysis results. The investigated parameters are the number of teeth and the number of elements. Using the analysis results, the number of elements and the number of teeth that guarantee the results are found. And then, the effects of the process parameters such as tool shape and temperature on the thread rolling are investigated. The analysis is carried out using DEFORM-3D. The results show that the flank angle and crest round have an effect on the thread rolling load. It is also shown that temperature have significant effects on the effective strain distribution, rolling load, and crack initiation. The crack initiation is predicted using the Cockcroft-Latham criterion.
Influence of Wax Molecular Weights on Wax Migration and Evaporation of Rubber Vulcanizates at Room Temperature
Im, Song-Hee ; Choi, Sung-Seen ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 397~400
Ozone caused the crack on the surface of a rubber article by oxidation of double bond at room temperature. Wax migrates to the surface of a rubber article and makes a physical barrier to prevent process of ozonation. We investigated change of molecular weight distribution of waxes in unfilled NR, SBR, and BR vulcanizates before and after aging at room temperature for 6 months. Migration and evaporation behaviors of wax in a rubber article at ambient conditions help understand a role of wax as an antidegradant and appearance contamination of a rubber article. The relative intensity distribution of n-alkanes of the NR specimen after the aging was shifted to higher molecular weight compared with the relative intensity distribution before the aging, while those of the SBR specimen before and after the aging did not show a big difference.
Crack Growth and Wear Properties of Silica-reinforced Styrene-butadiene Rubber Compounds: Effect of Processing Oil Type
Kang, S.L. ; Lee, J.Y. ; Go, J.Y. ; Go, Y.H. ; Kaang, S. ; Nah, C. ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 401~407
Commercial grades of solution styrene-butadiene rubbers extended with high aromatic oils having high polycyclic aromatic compounds (PCA) and low PCA oils were used to study the effect of the processing oil particularly on the crack propagation resistance and frictional wear resistance of the vulcanizates. The aromatic oil based vulcanizates exhibited superior fracture behavior over the low PCA oil extended vulcanizates based on tensile and trouser tear tests. Compounds with aromatic oil showed superior crack propagation resistance compared with those containing low PCA oil, especially at the lower ranges of tearing energy. In terms of frictional wear resistance, the aromatic oil extended compounds showed superior performance particularly in the lower frictional work (
) range but in the higher
range the low PCA oil extended vulcanizates performed better.
pH Dependence on the Degradation of Rhodamine B by Fe-ACF/
Composites and Effect of Different Fe Precursors
Zhang, Kan ; Oh, Won-Chun ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 408~415
Iron-loaded activated carbon fibers (Fe-ACF) supported titanium dioxide (
) photocatalyst (Fe-ACF/
) was synthesized using a sol-gel method. Three different types of Fe-ACF/
were obtained by treatment with different precursor of Fe, and characterized using BET, SEM, XRD and EDX analysis. The photocatalytic activity of Fe-ACF/
was investigated by the degradation of Rhodamine B (Rh.B) solution under UV irradiation. From the experimental results, it was revealed that Fe-ACF/
composites show considerable photocatalytic ability for the removal of Rh.B by comparing non-treated ACF/
composites. And photo-Fenton reaction with Fe element was incoordinately influenced due to different precursor of Fe. It clearly indicates that Fe-ACF/
composites prepared using
provided the highest photo-Fenton activity, then, which was affected by pH changes on the degradation of Rh.B.
Synthesis and Characterization of New Main Chain Liquid Crystalline Coumarin Compound with Ester Moiety
Lee, Jong-Back ; Kang, Byung-Chul ; Lee, Gang-Choon ; Lee, Dong-Jin ; Hideyuki, Kihara ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 416~422
4-(6-bromohexyloxy)benzoic acid was synthesized from benzyl 4-Hydroxybenzoate and 1,6-dibromohexane. It was reacted with hydroquinone to obtain a new mesogenic ester having an bromine group. One kind of new photoresponsive coumarin compound was prepared by the reaction of mesogenic ester with coumarin sensitive to the ultraviolet. Structures of the compound were identified by FT-IR and
-NMR spectroscopies. Their phase transition temperatures and thermal stability were also investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and x-ray diffraction analysis. From optical polarizing microscopy, the prepared compound was found to show enantiotropic liquid crystallinity with smectic and nematic textures.
The Non Newtonian Flow Mechanism and Rheological Properties of Polyurethane Melts
Kim, Nam-Jeong ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 423~428
The non-Newtonian flow curves of polyurethane melts were obtained by using a Physica cone-plate rheometer at various temperatures. The rheological parameters were obtained by applying non-Newtonian flow equation to the flow curves for polyurethane samples. When the polyurethane samples are under increasing-decreasing shear rate modes, the hysteresis loop and thixotropic behavior were shown. Polyurethane melts behave as strong gels when they are subjected to shear flow, but when the applied stress surpasses the yield stress, they exhibit non-linear viscoelasticity. Upon decreasing shear rate, its shear stress remains smaller than the values measured in the increasing shear rate mode, because of broken of its structure.
A Study on Synthesis of Starch-acryl Pressure Sensitive Adhesive by Soap-free Emulsion Polymerization
Song, Su-Hyun ; Kim, Young-Seok ; Cho, Ur-Ryong ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 429~435
The pressure sensitive adhesives (PSA) were synthesized by soap-free emulsion polymerization of acrylic monomers such as butyl acrylate, 2-ethyl hexyl acrylate, and acrylic acid in the presence of starch as a protective colloid and copolymer. The peel strength and holding power of PSA were increased with starch contents due to the enhancement of gel content, But the initial tackiness of PSA was decreased with starch contents. The contact angle analysis of PSA indicated that the wettability was increased with starch contents owing to the increase of polarity by hydroxy group in starch. In the pH measurement of emulsion with time for biodegradability, the starch in the PSA accelerated the lowering of pH due to the formation of organic acids followed by decomposition of starch.
Synthesis and Properties of Semi-Flexible Aromatic Polyesters Containing Pentamethylene Group in Main Chain
Bang, Moon-Soo ; Yoon, Doo-Soo ; Choi, Jae-Kon ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 436~441
Semi flexible polyesters containing aromatic rings and pentamethylene groups in the main chain were synthesized by direct polycondensation reaction. The structures of these polymers were investigated by
-NMR and FT-IR and the phase transition behavior was characterized with DSC, TGA and crossed polarizing microscope. Inherent viscosities (
) of polymers measured in phenol/p-chlorophenol/1,1,2,2-tetrachloroethane were between 0.46 and 1.30 dL/g. As increasing the linearlity of rigid moieties in polyster, melting transition temperatures (
) increased and solubilities in organic solvents decreased. P-H, P-mH and P-4H of the polymers formed turbid melts that showed stir-opalescence and nematic phase at the broad anisotropic region, However, P-R, P-C and P-2B did not exhibit any textures related to the liquid crystallinity.
Recovery Behaviors of NR, SBR and BR Vulcanizates from Circular Deformation
Jang, Joong-Hee ; Choi, Sung-Seen ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 442~446
Recovery behaviors of unfilled NR, BR, and SBR vulcanizates after aging with a circular deformation were compared to prevent the influence of reinforcing agent. Samples were aged at room temperature, 50, 70, and
for 10 days. Recovery increased by increasing the measurement time. Instantaneous recoveries less than 1.0 sec were obtained using the recovery variations with the measurement time. For aging at room temperature, difference in the recoveries of the rubber samples was not significant because the aging time was too short. However, for accelerated thermal aging at 50, 70, and
, difference in the recoveries of the rubber samples was significant. Degree of recovery of BR specimen was higher than those of the others, while that of SBR was lowest. However, for accelerated thermal aging at
, recovery of the NR sample was higher than that of the BR one. The initial recovery decreased by increasing the aging temperature and the decrement of SBR was larger than the others. The experimental results were explained with the resilience properties of rubbers and the crosslink density changes by thermal aging.
Synthesis of Polyester-diol and Exfoliation of Nanoclay through Esterification between Adipic Acid and Diethylene Glycol
Kim, Byung-Ju ; Lee, Sang-Ho ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 447~454
We synthesized polyester-diol containing Cloisite 30B which is exfoliated during the synthesis. First, esterification was conducted with excess adipic acids and two 2-hydroxyethyl groups of the tertiary ammonium tethered to Cloisite 30B silicate layer. Due to the small molecular size of adipic acid (
), it penetrated into the interlayer of Cloisite 30B, reacted with the 2-hydroxyethyl groups, and produced the tertiary ammonium that has the two ethyl-ester adipic acid groups, one methyl group, and one hydrogenated alkyl group. Through the esterification, the molecular size of the tertiary ammonium increased and as the result, the basal space of Cloisite 30B increased from
to more than
. The produced ethyl-ester adipic acid and unreacted adipic acid reacted with excess diethylene glycol ([COOH]/[OH]
) to be polyester-diol. The COOH conversion calculated from the acid value of the reactant mixture was 94%. The number average molecular weight and PDI of the produced polyester-diol were 830 g/mol and 1.2, respectively.
A Study on the Mechanical Properties of Organo-clay Filled NR/MMT Nanocomposites
Oh, Woo-Taek ; Lee, Eun-Kyoung ; Choi, Sei-Young ;
Elastomers and Composites, volume 44, issue 4, 2009, Pages 455~465
In this study, Organo-montmorillonite(MMT) was synthesized by intercalation of various amine(Octylamine, Dodecylamine, Dimethyldodecylamine, Octadecylamine) compounds into layered silicate. Natural Rubber(NR)/MMT nanocomposites were prepared by reinforcement of Organo-MMT. X-ray diffraction(XRD) and Scanning electron microscope(SEM) were employed to characterize the layer distance of Organo-MMT and the morphology of the NR/MMT nanocomposites. The structures of the synthesized Organo-MMTs were analyzed by the measurement of FT-IR. Cure characteristics, surface free energy and mechanical properties such as tensile strength, modulus and hardness of NR/MMT nanocomposites were carefully studied by contact angle meter, ODR, UTM, and hardness tester. FT-IR analysis showed a insertion of the alkyl and amine chains into the interlayers of the MMT. It was shown that the cure time of the organo-MMT was more decreased than that of
-MMT. Surface free energy and tensile strength of the NR/DDA-MMT nanocomposite were the highest. NR/ODA-MMT nanocomposite was the highest in hardness.