• Textile Coloration and Finishing
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• v.30 no.2
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• pp.107-116
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• 2018

Simplification of the manufacturing process in shoe making is essential to improve productivity and reduce production costs. To improve the adhesion of EVA foam used as a midsole, EVA/itaconated EPDM(EPDM-g-IA)(80/20wt%) blend was prepared using Torque Rheometer-Plasti-Corder, and 1,6-hexamethylenediamine/crosslinking agent/foaming agent/additive were mixed, followed by amidation reaction and foaming to prepare EVA/EPDM-g-IA foam for shoe midsole. In this study, we investigate the effect of the content of 1,6-hexamethylenediamine(0, 0.5, 1.0, 2.0, 3.0) on the mechanical properties, water-contact angle and adhesion of EVA/itaconated EPDM foam. As the content of 1,6-hexamethylenediamine increased, mechanical properties such as tensile strength, tear strength, tensile elastic modulus, hardness, and water-contact angle were lowered, but elongation at break and compression set(%) were increased. Both normal type and non-UV type adhesive strength increased with increasing diamine content. In particular, it was found that the adhesion strength of the non-UV type adhesion increased sharply with increasing diamine content. As a result, an adherend rupture occurs in a foam sample having a content of 1,6-hexamethylenediamine of 3phr. From this, it can be seen that the EVA/itaconated EPDM foam for shoe midsoles, which can be used for non-UV adhesion without primer and UV treatments, have been developed.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.121-129
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• 2008

Environmental friendly UV-curable coatings, having excellent hardness, gloss, mar and chemical resistance, are commonly used for the wooden flooring coatings. Especially epoxy acrylate oligomers are chosen for the wooden flooring coatings, due to their thermal stability and fast curing. In this study, we investigated the effect of the acrylate functionality on the thermal stability and surface hardness. The thermal degradations of monomers, oligomer, photoinitiator and formulated coatings with different acrylate functionality were measured using a thermogravimetric analysis (TGA). And the surface hardness was also measured with a pendulum hardness tester to compare relationship between the thermal stability and the physical property. The cured coatings became thermally stable by crosslinking during UV-curing. Both the thermal stability and surface hardness of cured coatings were improved with increasing acrylate functionality.

• Polymer(Korea)
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• v.31 no.1
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• pp.53-57
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• 2007

In this study, the flame retardancy and tensile properties of epoxy acrylate resin containing flame retardants based on phosphorous, bromine or metal hydroxide are investigated. It was found that the enhancement in flame retardancy of epoxy acrylate with decabromodiphenyl oxide (DECA) addition was better than the addition of 2,2,2-trichloroethyl dichlorophosphate (TCEDP). It seems that the high loading of TCEDP may delay the formation of crosslinking network and consequently decreases the conversion of epoxy acrylate. It was found that magnesium hydroxide ($Mg(OH)_2$) does not improve the flame retardancy of epoxy acrylate after added up to 40 wt%. The synergic effects were clearly observed for epoxy acrylate containing DECA/TCEDP combined flame retardants.

• Carbon letters
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• v.12 no.3
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• pp.138-142
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• 2011

Poly(vinyl alcohol) (PVA) composites with various graphite oxide (GO) contents (0 to 10 wt%) were prepared by sonicating the mixture of PVA and GO, followed by crosslinking with glutaraldehyde. GO was pre-treated with oxyfluorination ($O_2:F_2$ = 8:2) in order to modify the surface of GO to allow it to carry hydrophilic functional groups. PVA/GO composite hydrogels were characterized by scanning electron microscopy and Fourier-transform infrared spectrometer (FT-IR). The morphology of the PVA/GO composite hydrogels and the variations in soluble gel portion were investigated under various GO contents and UV irradiation doses. The variation in the chemical structure of photo degraded PVA/GO composite hydrogels was studied by FT-IR. The photochemical stability of PVA/GO composite hydrogels under UV irradiation was found to improve noticeably with increasing content of uniformly dispersed GO.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.857-861
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• 1994

UV curable hybrid systems have been investigated in the urethane acrylate based formulations where potentially irritant acrylate monomers have been substituted by vinyl ethers. Generally, among the systems studied, coating properties of hybrid system are superior to those of free radical hut inferior to those of cationic systems. When the content of acrylic oligomer is above 70%, however, hybrid system could render an excellent combination of coating and curing properties which outperforms both cationic and free radical systems. Photo-DSC has been used to follow the progress of crosslinking of various coating systems. Results imply that the critical factors in determining the curing rates of coating formulations are different depending upon the formulation characteristics. In the same type of hybrid formulations, the monomer/oligomer ratio rather than photoinitiator efficiency is the critical factor determining the curing rate of the systems.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.16 no.2_3
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• pp.59-65
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• 2010

Starch was modified with epichlorohydrin(ECH) to improve the miscibility with LDPE and LLDPE. Native starch or epichlorohydrin treated starch was mixed with grycerol and LDPE/LLDPE resin using a kneader and extruded using a single screw extruder to make pallets. The pallets were compression-molded at 145 into composite boards to evaluate their color, oxygen permeation, mechanical and thermal properties, and degradability under UV irradiation. Sheets with epichlorohydrin treated starch generally showed higher L-value than that of native starch blend sheets. The hunter b-values in both native starch blends and epichlorohydrin treated starch blends increased with Increasing starch contents. Tensile strength and percent elongation of sheets decreased with increasing starch contents. Tensile strength and percent elongation of sheets decreased with increasing starch contents. The degradability of blends under UV radiation increased with increasing starch contents in both blend types. The results represents that crosslinking of starch with epichlorohydrin may be a good method to improve miscibility of starch with petroleum-based materials.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1128-1134
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• 2012

We investigated a new method for patterning organic field-effect transistors (OFETs) using a photopatternable conducting polymer nanocomposite, consisting of poly(3-hexylthiophene) (P3HT)-coated gold nanoparticles (AuNPs) that had been modified with a photoreactive cinnamate group, to form P3HT-AuNP-CI. We found that the addition of the cinnamate group to the nanoparticle surface assisted the preparation of a solvent-resistive semiconducting film and preserved the P3HT ordering, which was interrupted by Au-P3HT interactions, as well as provided UV-controllable electrical properties. The P3HT-AuNPs-CI films could be microscale-patterned via a UV crosslinking photoreaction, represented as a promising photopatternable semiconductor material for use in advanced applications, with tunable electrical properties for fabrication of sub-micron and microscale electronic devices.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.112-117
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• 2021

In this study, a method of self-assembly of peptides based on irreversible covalent bonds was studied by mimicking a biological covalent bond, dityrosine bond. A tyrosine-rich short peptide monomer having the sequence of Tyr-Tyr-Leu-Tyr-Tyr (YYLYY) was selected to achieve a high-density of dityrosine bond. The peptide nanoparticles covalently self-assembled with dityrosine bonds were synthesized by one-step photo-crosslinking of a peptide using a ruthenium catalyst under visible light. The effect of the concentration of each component for the size of the peptide nanoparticle was studied using dynamic light scattering, UV-Vis spectroscopy, and transmission electron microscopy. As a result, the synthesis conditions for size of the peptide nanoparticles ranging from 130 nm to 350 nm were optimized.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.115-117
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• 1998

생물 발효 공정에 의해 생산된 부탄올 수용액은 농도가 희박하여 농축 공정이 필요하다. 기존의 농축 공정 중 투과증발공정은 공비혼합물이나 비점이 근접한 혼합물등을 분리하는데 에너지가 적게 들고, 분리 효과가 뛰어나며, 조업이 용이하고, 공정이 차지하는 공간이 적다는 장점을 가지고 있다. 산업적으로 관심을 갖는 5 wt% 이하의 부탄올 수용액을 효과적으로 농축시키기 위해 투과증발공정이 사용된다. 현재 투과증발공정에 사용되는 막에는 elastomeric membrane, plasma treated membrane, UV-grafted membrane, polymer blend membrane이 연구 개발되어 사용되고 있는데, 이중 플라즈마 처리방법을 통해 막을 제조 할 경우, 플라즈마 대상 물질의 선택 폭이 넓고, 분리물과 막간의 친화력을 향상 시키기 위해 분리물과 유사한 화학구조를 갖게 할 수 있으며, 형성된 코팅 층이 crosslinking되어 안정성을 갖는 장점이 있다. 따라서 본 연구에서는 플라즈마 처리법을 통해 투과증발막을 제조하고 제조된 막을 부탄올 농축에 사용하여 막의 성능을 조사하였고, 막의 성능과 접촉 각, sorption, heat of mixing간의 상관 관계에 대해 살펴 보았다.

• Journal of Periodontal and Implant Science
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• v.50 no.1
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• pp.14-27
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• 2020

Purpose: To overcome several drawbacks of chemically-crosslinked collagen membranes, modification processes such as ultraviolet (UV) crosslinking and the addition of biphasic calcium phosphate (BCP) to collagen membranes have been introduced. This study evaluated the efficacy and biocompatibility of BCP-supplemented UV-crosslinked collagen membrane for guided bone regeneration (GBR) in a rabbit calvarial model. Methods: Four circular bone defects (diameter, 8 mm) were created in the calvarium of 10 rabbits. Each defect was randomly allocated to one of the following groups: 1) the sham control group (spontaneous healing); 2) the M group (defect coverage with a BCP-supplemented UV-crosslinked collagen membrane and no graft material); 3) the BG (defects filled with BCP particles without membrane coverage); and 4) the BG+M group (defects filled with BCP particles and covered with a BCP-supplemented UV-crosslinked collagen membrane in a conventional GBR procedure). At 2 and 8 weeks, rabbits were sacrificed, and experimental defects were investigated histologically and by micro-computed tomography (micro-CT). Results: In both micro-CT and histometric analyses, the BG and BG+M groups at both 2 and 8 weeks showed significantly higher new bone formation than the control group. On micro-CT, the new bone volume of the BG+M group (48.39±5.47 ㎣) was larger than that of the BG group (38.71±2.24 ㎣, P=0.032) at 8 weeks. Histologically, greater new bone area was observed in the BG+M group than in the BG or M groups. BCP-supplemented UV-crosslinked collagen membrane did not cause an abnormal cellular reaction and was stable until 8 weeks. Conclusions: Enhanced new bone formation in GBR can be achieved by simultaneously using bone graft material and a BCP-supplemented UV-crosslinked collagen membrane, which showed high biocompatibility and resistance to degradation, making it a biocompatible alternative to chemically-crosslinked collagen membranes.