• Elastomers and Composites
• /
• v.41 no.2
• /
• pp.79-87
• /
• 2006

This study are conducted for the purpose of developing rubber material with noise and crack resistance. Cure characteristics, physical properties, thermal resistance, fuel resistance, abrasion resistance, crack resistance and noise resistance of NBR compounds with the various amounts of oleamide and aramid chip were investigated. From the measurements of cure characteristics and Mooney viscosities, cure characteristics of uncured rubber showed that a torque was decreased as the amount of oleamide increased. Hardness, modulus and elongation of rubber specimens tended to be reduced gradually, however, tensile strength remained unchanged as the amount of the oleamide increased. As a testing results of heat resistance for 70 hours at $120^{\circ}C$ and oil resistance far 70 hours at $40^{\circ}C$, tensile strength and elongation were all reduced. From the TGA/DSC analysis, there was no such a change observed in thermal characteristics of rubber materials. As a result of testing basic physical properties, abrasion resistance, noise resistance and crack resistance, the optimum ratio of oleamide to NBR was found to be 3 phr, while that of aramid to NBR 227001 was 1 phr.

• Polymer(Korea)
• /
• v.36 no.2
• /
• pp.235-244
• /
• 2012

A thiazole type accelerator MBT (2-mercapto benzothiazole) was added into silica filled natural rubber (NR) compound with various concentrations (0, 1, 2, 3, 4 phr). The effects of MBT on the cure rate, mechanical property, degree of rubber-filler interaction (${\alpha}_F$), crosslinking density, and viscoelastic property ($tan{\delta}$) were investigated. As accelerator concentration increased, the $t_{s2}$ and $t_{90}$ decreased and the crosslinking density and modulus at 300% elongation increased. The tensile strength and elongation increased up to 3 phr and no further increased at 4 phr. The $tan{\delta}$ value measured at room temperature was higher than that of the $70^{\circ}C$. The ${\alpha}_F$ value was not affected by the addition of MBT. The mechanisms for the vulcanization rate were reviewed.

• The Journal of Pediatrics of Korean Medicine
• /
• v.35 no.1
• /
• pp.63-75
• /
• 2021

Objectives The purpose of this study is to identify the characteristics of atopic dermatitis patients based on the personal health records (PHR) according to age and Sasang Constitution, and to find basic data for daily life management using the personal health record. Methods We analyzed the characteristics of atopic dermatitis patients based on PHR (symptoms, emotional state, SCORAD Index, five viscera weakness questionnaire, etc.), and Sasang Constitution collected for 6 weeks in 34 patients (or guardians). Results Each item of the SCORAD Index score in children and adolescents showed that children and adolescents have significantly higher edema than adults. However, repeated measurement of the SCORAD Index showed a significant positive improvement over time regardless of age and constitution. In terms of the symptoms of atopic dermatitis, there was a significant correlation between age and swelling, quality of life and effusion, pruritus (itch) and sleep disturbance in relation to the general characteristics of the subject. In the five visceral weakness scores, adults had significantly higher spleen weakness, liver weakness, kidney weakness scores than in children and adolescents. All results showed a high tendency to have a high lung weakness score, which was more pronounced in children and adolescents. Conclusion This study is meaningful to confirm the correlation between SCORAD Index items related to the symptoms of atopic dermatitis, and to identify trends for specific items by ages and Sasang Constitution.

• Polymer(Korea)
• /
• v.31 no.4
• /
• pp.283-288
• /
• 2007

Polymer blends containing poly(acrylonitrile-butadiene-styrene) (ABS) and polycarbonate(PC) (70/30, wt%) with compatibilizer were prepared using twin screw extruder. Compatibilizers were prepared by reactive extrusion with the ABS, maleic anhydride(MAH) and dicumyl peroxide(DCP) using twin screw extruder In the ABS/PC (70/30) blends, tensile strength did not change significantly, but increased from 52.25 to 55.03 MPa when the ABS-g-MAH was added in the amount of 5 phr. From the results of rheological properties, storage modulus of the ABS/PC/ABS-g-MAH blends at low frequencies showed lager value than that of the ABS/PC(70/30) blend. From the results of the morphological properties of the ABS/PC(70/30) blend, it was observed that the drop size of the PC ranged from 1.2 to $1.5\;{\mu}m$ and did not change significantly with the addition of the ABS-g-MAH($1{\sim}10\;phr$). From the results of the storage modulus, complex viscosity, and tensile strength of the ABS/PC (70/30) blends, it is found that the ABS-g-MAH is an effective compatibilizer in the ABS/PC (70/30) blends when the ABS-g-MAH is added in the amount of 5 phr.

• Elastomers and Composites
• /
• v.37 no.4
• /
• pp.224-233
• /
• 2002

This study has investigated the flame retardant properties of EPDM rubber with the addition of various flame retardants. Carbon black, stearic acid, zinc oxide cross-linking agent were mixed with EPDM rubber to produce the base rubber E0 without the addition of flame retardants. Phosphorus flame retardant Tricrecyl phosphate(TCP) was added to E0 in 0.5, 1, 1.5, 2 phr to make E1~E4 samples and red phosphorus was added in 3, 6, 9, 12 phr to make E5~E8 samples. A flame retardant of the bromine family Decabromodiphenyloxide(DBDPO), and a chlorinated paraffin retardant of the chlorine family was added to E0 in 3, 6, 9, 12 phr to make E9~E12 and E13~E16 samples, repectively. Basic physical properties such as tensile strength, tear strength and hardness were measured for all the rubber samples with various flame retardant additions. There was no substantial differences. On the other hand, Oxygen index and UL94 were measured to study flame retardant properties. From oxygen index measurements E0 sample showed a value of 23.5%, indicating the improvement of flame retardant properties. Also from UL94 measurements, it was found that addition of red phosphorus resulted in maximum flame retardant effect. It was found that increasing the amount of addition resulted in decreasing combustion rate and improving flame retardant effect regardless of the kind of flame retardant.

• Journal of Society of Preventive Korean Medicine
• /
• v.24 no.2
• /
• pp.71-82
• /
• 2020

Objectives : The purpose of this study is to evaluate clinical utilization by measuring compliance with the use of mobile health applications (AtopyPHR developed in a previous study) for patients with atopic dermatitis. Methods : Based on the AtopyPHR and the input period and frequency survey results for each symptom item, a scenario for measuring compliance was derived. The study period was 4 weeks. Participants installed AtopyPHR app and Telegram app on their smartphones, conducted user training on the app, and recorded symptoms using the app for 4 weeks. At the 2nd and 4th week visits, the AtopyPHR data recorded by the user can be viewed on the web page and used for medical decision. Compliance was analyzed by the date the symptoms were recorded. Results : There were 28 participants, all (100%) were compliant, and the compliance was 96.8. The patients were 1 to 18 years old, and the average age was 8.2±5.7 years, 10 males and 18 females. The actual date of participation in recording symptoms was 28.6±0.56 on average. Compared to Week 1, compliance decreased at Week 2, and Week 4 had the highest compliance. Daily check, daily emotion, stool/urine/sleep, and meal management showed high compliance, SCORAD and quality of life were higher than required to record. Conclusions : AtopyPHR was effective in compliance. The results of this study could be used to collect personal health data in daily life through the AtopyPHR, improving participant compliance. It is considered to be meaningful because it measured the compliance with the symptom record actually recorded using the mobile app rather than a questionnaire. This study may be useful not only for personal health care but also for medical decisions, as opinions are given by experts who treat atopic dermatitis.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1988-1990
• /
• 2004

In this paper, we investigated electrical property of epoxy resin which includes elastomers to improve electrical and mechanical property, as varied to additive elastomer contents. There are four samples with 5[phr], 10[phr], 15[phr] and 20[phr]. We meIt was experimented with changing temperature($-80^{\circ}C{\sim}50^{\circ}C$) and frequency (10Hz, 60Hz, 1kHz, 10kHz) According to the experimental results, when the additive elastomer contents are increasing, the permittivity and tan${\delta}$ has very high value in particular at low frequency and high temperature. It also appears that those increasing rates relate to additive elastomer contents. That is to say, even though epoxy resin are improved in mechanical property according to elastomer contents, the elastic epoxy can has bad dielectric characteristics for electrical power application.

• Elastomers and Composites
• /
• v.36 no.1
• /
• pp.37-43
• /
• 2001

Influence of the filler composition ratio on cure characteristics and bound rubber content of the compounds and on physical properties of the vulcanizates were studied using both silica and carbon black-filled styrene-butadiene rubber (SBR) compounds with the total filler content of 80.0 phr. The bound rubber content increased slightly with increase of the silica content ratio. The viscosity also increased with increasing the silica content ratio, especially increased steeply after the silica content of 60.0 phr. The cure times obtained with a rheometer, t2, t40, and t90, are increased by increasing the silica content ratio and the cure rate decreased. The delta torque increased with the increased silica content ratio. Variation or the modulus with the silica content ratio showed a decreased trend though the delta torque increased. The tan ${\delta}$ at $60^{\circ}C$ decreased with increased of the silica content ratio.

• Elastomers and Composites
• /
• v.6 no.2
• /
• pp.47-63
• /
• 1971

We have studied the blending effects of Diene 33R and styrenebutadiene rubber at various blending ratios of 100/0, 70/30, 50/50, 30/70, 0/100, and of carbon black HAF and ISAF at various compounding ratios of 55 PHR, 65 PHR, 75 PHR for tyre tread rubber. As the results, it was found that ; 1. For tyre tread rubber, when the blending ratio, Diene NF 35R/SBR 1778, indicated 30/70, the physical properties we examined were most excellent. 2. Excellent result was obtained in case of carbon black compounding ratio of 65 PHR. The compounding of ISAF made better result than that of HAF for abrasion quantity, tearing strength, and tensile strength. 3. Heat buildup obtained from compounding carbon black HAF indicated low temperature than that from compounding carbon black ISAF. As the compounding amount of carbon black increased, the heat buildup improved. And as the blending amount of Diene NF 35R decreased, the heat buildup dropped. 4. Carbon black was more efficient to SBR than to Diene Rubber. 5. It is a shortage that elongation revealed low price.

• Composites Research
• /
• v.36 no.5
• /
• pp.355-360
• /
• 2023

Epoxy-based carbon fibers reinforced plastic (CFRP) exhibit limitations in their suitability for industrial applications due to high brittleness characteristics. To address this challenge, extensive investigations are underway to enhance their toughness properties. This research focuses on evaluating the toughening mechanisms achieved by Polyamide 6 particles(p-PA6) and Carboxyl-Terminated Butadiene-Acrylonitrile (CTBN) elastomer, with a specific emphasis on utilizing minimal additive quantities. The study explores the impact of varying concentrations of p-PA6 and CTBN additives, namely 0.5, 1, 2.5, and 5 phr, through comprehensive Mode I fracture toughness and tensile strength analyses. The inclusion of p-PA6 demonstrated improvements in toughness when introduced at a relatively low content of 1phr. This improvement manifested as a sustained fracture behavior, contributing to enhanced toughness, while simultaneously maintaining the material's tensile strength. Furthermore, the investigation revealed that the incorporation of p-PA6 affected in particle aggregation, thus influencing the overall toughening mechanism. Incorporation of CTBN, an elastomeric modifier, exhibited a pronounced increase in fracture toughness at higher concentrations of 2.5 phr and beyond. However, this increase in toughness was accompanied by a reduction in tensile strength, resulting in fracture behavior similar to conventional CFRP exhibiting brittleness. The synergy between pPA6, CTBN and CFRP appeared to marginally enhance tensile strength under specific content conditions. As a result of this study, optimized conditions for the application of the p-PA6, CTBN toughening technology have been identified and established.