Guni Kim

Synthesis and properties of styrene-EPDM-vinyl acetate graft polymer

The styrene–EPDM–vinylacetate (SEV) graft polymer, which linked respectively the styrene (St) unit and vinylacetate the (VAc) unit to the ethylene–propylene–diene terpolymer (EPDM) backbone was synthesized by two-step graft polymerizations: First the graft polymerization of VAc onto EPDM was carried out, and then St was added successively in the prepolymerized solution and further polymerized for a given period to obtain SEV. The effects of concentration of EPDM and an initiator, mole ratio of VAc to St, polymerization time, temperature, and solvent were examined on the graft polymerizations. The synthesized graft polymers (SEVs) that have different contents of St or VAc were identified by Fourier transform IR spectrum. The highest graft ratio has been obtained by 10 wt % of EPDM, 1.0 mole ratio of VAc to St, and 1.0 wt % of BPO in toluene for 48 h at 70°C. The glass transition temperature of SEV is lower than that of poly(vinyl acetate) (PVAc) and polystyrene (PS). The thermal stability of SEV is higher than that of PVAc, PS, and the acrylonitrile–butadiene–styrene (ABS) resin. The tensile strength of SEV was improved as compared with that of EPDM. The light resistance and weatherability of SEV were better than those of ABS.

Dismantlement studies of dismantlable polyurethane adhesive by controlling thermal property

This paper investigated the design of dismantlable polyurethane adhesives and dismantling method. To study the dismantlement property of dismantlable polyurethane adhesive by controlling thermal property, we synthesized polyurethane adhesive with various hard segment contents and used thermally expansive microcapsules. The dismantlement of bonded adherend was caused by the expansion of the adhesive layer with the expansion of the thermally expansive microcapsule and softening of the adhesive. For the dismantlement of bonded adherend, the adhesive is needed to have low storage modulus at the expansion temperature of thermally expansive microcapsule. High storage modulus of the adhesive was good for the bonding strength but not for dismantlability. In our study, the dismantlability became better as the hard segment content of adhesive decreased and the bonding strength and heat-resistance were excellent when the hard segment content was more than 25% because of high storage modulus and physical property. Consequently, optimum hard segment content was 25%, which showed excellent adhesion strength and dismantlement of bonded adherend was possible with microwave treatment for 4 min. Using zinc oxide with high dielectric constant could shorten microwave treatment time needed for the dismantlement of the bonded adherend to 3 min by enhancing the heating efficiency of the adhesive.

Study on Mechanical and Thermal Properties of Fiber-Reinforced Epoxy/Hybrid-silica Composite

Recently, carbon fiber composites have been widely used as structural reinforcement materials of buildings, replacing reinforcing bars or concrete. And the increase in use of super fibers such as aramid and high strength PE, which is aimed at improving the reinforcement properties, has resulted in a demand for a resin system with excellent mechanical and thermal properties. In this research, a fiber-reinforced composite has been produced by using the super fibers such as carbon fiber or aramid fiber, reinforcement resin and the silica hybrid compound containing epoxy group. This study was carried out to confirm the effect of the silica hybrid on mechanical properties, heat resistance and adhesion strength of a fiber-reinforced epoxy composite, which was produced by blending silica or introducing silica hybrid through covalent bonds. And the silica hybrid containing epoxy group, which may be introduced to the structure of fiber-reinforced epoxy composite through covalent bonds caused by reaction with a hardener, has been used, so that the heat resistance and adhesion strength could be improved.

Viscoelastic, Mechanical and Recycling Properties of Grafted EPDM Containing Organic Salt Group

The effects of the functionality and the single or combination of secondary bonding on the mechanical and thermo-reversible properties of the grafted ethylene propylene diene rubber (EPDM) modified with acrylic monomers including organic salt were investigated. The storage modulus of grafted EPDM containing organic salt was maintained higher than that of cross-linked EPDM by sulfur at specific temperature, but it was observed that the secondary bonding was weakened and the storage modulus was decreased sharply at elevated temperature. When the functional group for inducing secondary bonding was introduced in EPDM, it had excellent mechanical properties by formation of aggregates between grafted EPDM molecules. For those with both ionic interaction by organic salt group and the hydrogen bonding by amide group, the recycle properties were excellent maintaining 90% of their initial mechanical properties even after 5 times recycling processes.

Melt Grafting of Citraconic Acid onto an Ethylene-Propylene-Diene Terpolymer (EPDM) -Effect of Reaction Conditions and Initiator Type on the Melt Grafting of Citraconic Acid onto EPDM-

Melt grafting of citraconic acid (CCA) onto an ethylene-propylene-diene terpolymer (EPDM) with various peroxide initiators was performed using a Haake Rheocorder. Finding the optimum running condition and concentration is critical for effective grafting and performance of grafted material. Therefore, this study focused on the effects of mixing (reaction) condition and monomer/initiator dosages on the grafting degree, grafting efficiency and crosslinking degree (gel content), melt flow index and mechanical properties of CCA-g-EPDM. As the grafting degree/crosslinking degrees increased, the tensile strength increased significantly, but elongation at break and melt flow index decreased. The initiator 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101) appeared to meet for the best grafting(2.31%). The grafting degree increased markedly with increasing monomer CCA/initiator T-101 contents. The grafting degree also increased with increasing mixing temperature/time, and then leveled off or decreased/increased a little. The optimum monomer/initiator dosages and reaction temperature/time were found to be about 5/0.05 wt% and 180 °C/15min, respectively. 요 약:Haake Rheocorder로 각종 과산화물 개시제를 사용하여 ethylene-propylene-diene terpolymer (EPDM) 에 단량체 citraconic acid (CCA)을 용융 그라프트 중합을 하여 그라프트 중합물 CCA-g-EPDM을 얻었으며, 이 때 효율적인 그라프트 정도와 우수한 성능을 지닌 그라프트 중합물을 얻기 위해서 최적의 반응조건과 최적의 단량체/개 시제 농도를 찾는 것은 매우 중요하다. 따라서 본 연구에서는 반응조건과 단량체 및 개시제 함량이 CCA-g-EPDM의 그라프트 정도, 그라프트 효율, 가교정도 (겔화도), 용융흐름지수(MI) 및 기계적 물성 등에 미치는 영향에 초점을 맞추었다. 그라프트 정도와 가교도가 증가함에 따라서 인장강도는 상당히 증가한 반면, 파괴신도 및 MI는 감소하였다. 개시제 중에서 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101)가 가장 우수한 그라프트 정도 (2.31 %)를 나타내었으며, CCA와 T-101의 함량이 증가함에 따라 그라프트 정도가 크게 증가하였다. 그리고 그라프트 정도는 반응(혼합)온도 및 반응시간이 증가함에 따라 역시 증가하다가 어느 온도/시간 이상에서는 안정화 혹은 약간 감소하는 경향을 나타내었다. 이러한 영향으로 결과로부터 최적의 단량체/개시제 농도는 5/0.05 wt%이었으며, 최적 의 반응온도/시간은 180 C/15분인 것을 알 수 있었다.

Graft Copolymerization of Acrylic Monomer Containing Aromatic Carboxylic Acid Group onto EPDM and Their Mechanical Properties

ABSTRACT ：In this study, p -acryloyloxybenzoic acid(ABA) was synthesized with p -hydroxybenzoic acid(HBA) and acryloylchloride(AC). The synthesized ABA monomer was grafted onto ethylene-propylene-diene rubber(EPDM) in toluene usingbenzoyl peroxide(BPO) as an initiator. The structures of ABA and EPDM- g -ABA were characterized by FT-IR, 1 H-NMR,and 13 C-NMR spectrometer. The graft ratio of EPDM-g-ABA increased with increasing the concentration of the initiatorand the monomer. Mechanical properties such as tensile strength and compression set of the EPDM- g -ABA were improvedwith increasing the graft ratio. The T g and initial decomposition temperature were also increased with increasing the graftratio. Keywords ： graft copolymerization, EPDM, graft ratio, p-acryloyloxybenzoic acid, thermoplastic elastomer † Corresponding Author. E-mail: stoh@kiflt.re.kr Ⅰ. 서 론 에틸렌-프로필렌-디엔 고무(EPDM)은 에틸렌과 프로필렌으로 이루어진 랜덤 공중합체에 제3성분으로 디엔 단량체를 도입한 올레핀계 열가소성 탄성체로 주 사슬에 소량의 이중결합을 지니는 디엔 단량체가 결합되어 있으며 이들 이중결합은 가교에 의하여 포화되기 때문에 내후성, 내오존성, 내산화성 및 내열성이 뛰어나 자동차 에어백 커버 , 인테리어 스킨, 인스트루먼트 패널, 튜브, 파이프, 필름 PVC 대체재로서 사용되고 있으나 낮은 탄성 및 내스크래치성 , 취약한 내열성, 낮은 점착성 및 도장성, 실온에서의 플라스틱 거동 등의 단점이 있다. 합성 고무로 대표되는 열경화성 탄성체가 화학적 공유결합 즉 비가역적인 가교결합을 가지는 반면에 EPDM의 연질상은 열가소성 탄성체 특유의 고무 탄성을 발현하고 , 경질상이 용융/가소화하여 독특한 성형 가공성을 발현한 후 다시 경화함으로써 소성 변형을 방지하는 기능을 나타낸다.

Mechanical and dismantlement adhesion properties of grafted EPDM-silica hybrid

This study was carried out to confirm the effects of functional groups that could derive secondary bonding and silica contents on mechanical properties and thermo-reversible characteristics of grafted EPDM-silica composites, which was produced by blending silica or introducing silica hybrid through ionic bonding after grafting methacrylic acid onto EPDM. The storage modulus of graft copolymer had appeared to be higher than cross-linked EPDM vulcanizate at room temperature, and decreased by a gentle slope as temperature increased, and then began to decrease more sharply as secondary bonding force became weaker at higher temperature. When silica hybrid was introduced through ionic interaction, storage modulus and mechanical properties were found to be higher due to not only hydrogen and ionic bonding, but also nanosized silica particles, which were bonded to the elastomer structure in uniformed distribution. When the graft copolymer had only hydrogen bonding, recycling of the elastomer caused mechanical properties to be reduced by 20–30%. However, the recycling characteristics of elastomers having both hydrogen and ionic bonding were excellent as more than 90% of their initial mechanical properties were maintained even after five times of reprocessing. Graft copolymer composite had better adhesion strength with other rubber due to increased polarity than EPDM, and dismantlement of bonded adherends was possible by applying heat treatment of microwave.

Induction heating of adhesive for shoe manufacturing

This paper describes the induction heating of adhesive containing conductive fine particles for shoe assembly. The particles are heated on the principle of induction heating to increase the adhesive temperature. To do this, a 5kW induction heater is constructed and several experiments are conducted to design working coil. Finite Element Analysis is also conducted and the analytical and experimental results are compared to find optimal coil shape. From this study, we can develop a prototype of the induction heater for shoe manufacturing.

Dismantlment Adhesion Properties of Dismantlable Polyurethane-Silica Hybrid Adhesive

In order to determine the dismantlement property of dismantlable polyurethane adhesive by controlling thermal property, polyurethane (PU)-silica hybrid adhesives with softening properties at a certain temperature were synthesized and used to fabricate dismantlable polyurethane adhesive by mixing with thermally expansive microcapsule. Their thermal properties were characterized by DSC and DMTA, and bonding strength as well as dismantlement properties were also evaluated depending on the type of PU, heating triggers, and treatment conditions. The specimens adhered by dismantlable PU adhesive were readily peeled off after the treatment of microwave irradiation, and those by PU-silica hybrid resin were much more easily peeled off after microwave irradiation for 2 min. This result was attributed to the softening of adhesive and volumetric expansion of thermally expansive microcapsule. In addition, the dismantlable adhesive should have low storage modulus at the expansion temperature of thermally expansive microcapsule to have dismantle adhesion properties.

Melt Grafting of EPDM and Itaconic Acid: Effect of Reaction Conditions and Initiator Type/Concentration

Innovation Material Research Group, Korea Institute of Footwear and Leather Technology, Busan 614-100, Korea(Received April 30, 2014, Revised June 30, 2014, July 16, Accepted July 18, 2014)요 약：유기과산화물 개시제를 사용하여 ethylene-propylene-diene terpolymer (EPDM)에 단량체 itaconic acid (IA)를 용융 그라프트시켜 그라프트 중합물 EPDM-g-IA을 얻었다. 이 과정에서 효율적인 그라프트 율과 인장강도 특성이 우수한 그라프트 중합물을 얻기 위한 최적의 반응조건과 단량체 및 개시제 농도를 구하는 것은 매우 중요하다. 따라서 본 연구에서는 그라프트 온도 및 시간 등의 반응조건, 개시제 종류 및 함량, 모노머 함량이 EPDM-g-IA의 그라프트 율, 그라프트 효율, 용융흐름지수(MI) 및 겔 함량 등에 미치는 영향을 고찰하였다. 개시제 중에서 2,5-di-methyl-2,5-di(tert-butyl peroxy)-hexane (T-101)가 가장 우수한 그라프트 정도 (1.91 %)를 나타내었으며, IA와 T-101의 함량이 증가함에 따라 그라프트 율은 증가하였다. 또한 그라프트 율은 반응(혼합)온도 및 반응시간이 증가함에 따라 역시 증가하다가 특정 온도/시간 이상에서는 안정화 혹은 약간 감소하는 경향을 나타내었다. 이러한 결과들로부터 최적의 단량체와 개시제 농도는 5wt%와 0.05 wt%이었으며, 최적의 반응온도와 시간은 160℃와 15 분인 것을 알 수 있었다. 이타콘산 그라프트 EPDM은 미반응 EPDM에 비해 인장강도 등의 기계적 물성이 증가함을 확인할 수 있었다.ABSTRACTMelt grafting of itaconic acid (IA) onto an ethylene-propylene-diene terpolymer (EPDM) with various organic peroxide initiators was performed. Finding the optimum mixing conditions and concentration of ingredients is critical for effective grafting and optimum properties of grafted materials. This study focused on the effects of mixing conditions (temperature and time), initiator type/concentration and monomer concentration on the grafting degree and efficiency, melt flow index, and gel content of EPDM-g-IA. The initiator, 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101), appeared to meet for the best grafting degree (1.91%). The grafting degree increased markedly by increasing the amounts of monomer IA and initiator T-101. The grafting degree also increased by increasing mixing temperature and time. The optimum monomer and initiator concentrations and reaction temperature and time were found to be about 5wt%/0.05wt% and 160°C/15min, respectively. It was found that the physical properties of EPDM-g-IA were higher than those of the pristine EPDM.Keywordsmelt grafting, itaconic acid, ethylene-propylene-dieneterpolymer (EPDM), initiator