• Polymer(Korea)
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• v.36 no.5
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• pp.617-621
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• 2012

PHEAs [${\alpha}$,${\beta}$-poly(2-hydroxyethyl-DL-aspartamides)], a class of poly(amino acid), have been widely studied as biodegradable and biocompatible polymers for potential biomedical and pharmaceutical applications. In this study, we investigated a homogeneous blend of PHEA with poly(N-vinyl pyrrolidone) (PNVP) and its semi-IPN (semi-interpenetrating polymer network) gels. Blend films were prepared by a solution casting method. The resulting blends were totally transparent over the whole composition ranges and the single $T_g$, changing monotonously with composition, was observed by DSC to confirm the miscibility between these two polymers. FTIR was used to discuss the possible hydrogen-bonding interaction between polymers. In addition, semi-IPN type gels were prepared by chemical crosslinking of PHEA/PNVP blend solution using hexamethylene diisocyanate (HMDI) as a crosslinking reagent. The prepared gel was characterized by their swelling property and morphology.

• Macromolecular Research
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• v.8 no.2
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• pp.89-94
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• 2000

A semi-interpenetrating network (IPN) was prepared for a temperature-sensitive polymer system composed of sodium alginate and poly (N, N-dimethylaminoethyl methacrylate (DMAEMA)-co-ethyl acrylamide (EAAm)). The role of sodium alginate is to provide crosslinked network and that of poly(DMAEMA-co-EAAm) is to provide temperature responsiveness to the polymer system. Semi-IPN gel shows temperature-induced swelling transition at the same temperature of the lower critical solution temperature of poly(DMAEMA-co-EAAm) and its swelling kinetics is manipulated by the control of crosslinking densitv.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.11
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• pp.994-1000
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• 2003

In this study, gel polymer electrolytes (GPE) with semi-interpenerating network of poly (methyl methacrylate) and hexanediol dimethacrylate were synthesized and their electrochemical performances were evaluated. LiCoO$_2$/GPE/graphite cells were prepared and their performances depending on discharge currents and temperatures were evaluated. The precursor containing 5 vol% curable mixture had a low viscosity relatively. GPE showed good electrochemical stability up to potential of 4.8 V vs. Li/Li$\^$+/. Ionic conductivity of the gel polymer electrolyte at room temperature and -20$^{\circ}C$ was ca. 5.9 and 1.4${\times}$10$\^$-3/ Scm$\^$-1/, respectively. LiCoO$_2$/GPE/graphite cells showed good rate capability, low-temperature performance and cycleability.

• Polymer(Korea)
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• v.26 no.6
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• pp.767-777
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• 2002

In this work, biodegradable modified aliphatic polyester (MAP) in tetrafunctional epoxy (4EP) resin was investigated in terms of cure kinetics, thermal stabilities, rheological properties, and mechanical interfacial properties. DSC results of the blends show that the cure activation energies (E$\_$a/) were increased in 10 wt% of MAP compared with neat 4EP, due to the increasing intermolecular interaction between 4EP and MAP. The decomposed activation energies (E$\_$t/) derived from Coats-Redfern method, were increased within the 10∼30 wt% composition range of MAP contents, resulting from increasing the cross-linking density of the blend system. Rheological properties of the blend system were investigated under isothermal condition using a rheometer. Cross-linking activation energies (E$\_$c/) were determined from the Arrhenius equation based on gel time and curing temperature. As a result, the E$\_$c/ showed a similar behavior with E$\_$a/. The fracture toughness (K$\_$IC/) of the mechanical interfacial properties was discussed in semi-IPN behaviors of the casting specimen.

• Polymer(Korea)
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• v.33 no.1
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• pp.39-44
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• 2009

Polymer substrates were fabricated by using poly (phenylene ether) as a base resin, N,N'-m-phenylenedimaleimide (PDMI) as a crosslinking agent and decabromodiphenylethane as a flame retardant. The effects of crosslinking agent and flame retardant on physical properties such as dielectric property of the substrate were investigated. Thermal curing feature of PDMI with or without an initiator was analyzed by DSC, and then, PPE-PDMI test compositions were designed based on this result. Composite sheets were cast by film coater, laminated under vacuum and pressure, and then, the changes of dielectric constant, dielectric loss, peel strength, solder heat resistance and inflammability according to increasing amount of PDMI and flame retardant were evaluated, Dielectric constant and dielectric loss showed increasing trend with increasing amount of PDMI and flame retardant, but solder heat resistance and inflammability were improved. Peel strength was obtained higher than 1 kN/m when PDMI above 10 wt% was added, but slightly decreased as the amount of flame retardant increased. From the measured gel contents, the reaction mechanism of PPE-PDMI system was deduced to the formation of network structure by crosslinking PDMI with PPE rather than the formation of semi-IPN structure. In conclusion, the polymer composite substrate materials with dielectric constant of 2.52$\sim$2.65 and dielectric loss below 0.002 at 1 GHz were obtained and they will be proper for high frequency applications.

• Journal of the Korean Wood Science and Technology
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• v.41 no.2
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• pp.134-140
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• 2013

UV curing was introduced via a chemical treatment by adding small amounts of a hexafunctional acrylic monomer and a photoinitiator to improve the mechanical properties of PLA. This study also employed a semi-interpenetrated structured polymer network through the process of UV-curing. The UV curing behaviors were investigated using FTIR-ATR spectroscopy and gel fraction determination. Also, the tensile strength was investigated with different hexafunctional acrylic monomer contents and UV doses. The results showed that the crosslinking of UV-induced chemically treated PLA started at a low content of hexafunctional acrylic monomer, resulting in a significant improvement of the mechanical properties compared to those of neat PLA due to crosslinking.