전자선 조사에 따른 Polyolefin Elastomer의 특성 변화 분석

염제성,주형태,한형순,김정철 한국고분자학회 2008 한국고분자학회 학술대회 연구논문 초록집 Vol.33 No.2

Effects of the Shape and Surface Treatment of Clay on the Process of Uniaxially Drawn Low-Density Polyethylene/Clay Composites Films

염제성,반하람,장정호,김정철 한국고분자학회 2020 Macromolecular Research Vol.28 No.4

Fabricating composite films by dispersing clay in a polymer can provide functionalities such as antibiotic action and chemical adsorption. In this study, the effects of the shape and surface treatment of clay on the gas barrier properties, mechanical properties, thermal properties, and processing characteristics of polymer/ clay composite films were investigated. Halloysites (HNTs) and vermiculites (VMTs), which are popular clays of the nanotube and nanoplate types, respectively, that are often employed to achieve functionality as they facilitate the carrying of chemicals, were incorporated into low-density polyethylene (LDPE). The effects of chemical treatment of the clay surface on the dispersibility of the clays in the polymer composites and on their properties were examined. Furthermore, the effects of the shapes and surface treatment of the clays on the drawabilities of the composite films, as well as the mechanical properties of the composite films according to the draw ratio were investigated. In the manufactured LDPE/clay composite films, the HNTs showed better dispersibility than the VMTs. After surface treatment with hydrochloric acid, the dispersibility improved relative to that before chemical treatment. With increasing clay content, the initial moduli of the composite sheets improved, but the tensile strengths and strains decreased. When VMTs were used, the gas barrier property of the composite film improved as the clay content increased; however, when HNTs were used, the gas barrier property decreased with increasing clay content. When the clay surface was chemically treated, the drawabilities of the LDPE composites improved compared to those prior to surface treatment, and the drawabilities of the HNT composites were greater than those of the VMT composite. The maximum draw ratio of the surface-treated HNT composite film was the highest at 4.0, and the tensile strength increased by up to ~3 times compared to that of the undrawn film. As the draw ratio increased, the gas barrier property, crystallinity, and the degree of orientation also increased.

Effect of Electron Beam Irradiation on Gas-barrier Property of Biaxially Drawn Nylon/Montmorillonite Nanocomposite Films

염제성,박종진,김정철 한국고분자학회 2020 Macromolecular Research Vol.28 No.10

This study aimed to improve the properties, such as tensile strength and gas barrier properties, of nylon/montmorillonite nanocomposite films for them to be better suited for packaging applications. In this study, organic/inorganic nanocomposite films were fabricated by melt compounding with a twin-screw extruder using a polyamide (m-xylene diamine 6 nylon; MXD6) as the polymer matrix and organic nanoclay (montmorillonite; MMT) as a filler. An electron beam (EB) was irradiated onto the fabricated nanocomposite film and its effects on the film properties were examined. Biaxial drawing and annealing were conducted after EB irradiation to investigate the orientation of molecular chains and crystallization. Transmission electron microscopy revealed that the clay nanoparticles were finely dispersed in the polymer matrix. Furthermore, the EB irradiation-induced polymer crosslinking was verified by measuring the gel content in the films. Finally, the thermal properties of the film were verified by differential scanning colorimetry (DSC), and the light transmittance was examined using a UV-visible spectrophotometer. Application of the sequential process of EB irradiation, biaxial drawing, and annealing on the MXD6/MMT-5 wt% nanocomposite films increased their tensile strength by 56% and decreased thermal shrinkage by 26%, with a minimal loss of the optical transparency. Increasing both nanoclay contents and draw ratios resulted in improved oxygen-gas barrier properties. In particular, the gas barrier property of the MXD6/ MMT-5 wt% film approximately doubled compared with that of the untreated specimen. The thermal analysis by DSC revealed that the crystallinity decreased because of the addition of MMT and the EB irradiation.

Influence of Surface Treatment of CaSO4 on the Drawability and Physical Properties of the PBAT/PLA/CaSO4 Composite Sheet

공영준,염제성,공태웅,허양일,김정철 한국고분자학회 2022 Macromolecular Research Vol.30 No.9

This study investigated the effect of surface treatment of CaSO4 on the physical properties of the composite film manufactured using an inorganic additive CaSO4 and the biodegradable polymers, poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA). Using a twin-screw extruder, the CaSO4 content of the PBAT/CaSO4 composite was prepared to be 1, 5, and 10 wt%, and the surface treatment of CaSO4 with stearic acid was studied for changes in mechanical properties and dispersibility of the composite. The surface-treated CaSO4 showed improved dispersion in the matrix polymer and improved strength and elongation compared to before surface treatment at all contents of the PBAT/CaSO4 composite. In addition, using a small amount of PLA, PBAT/PLA/CaSO4 composite sheets were prepared and biaxially stretched. The draw ratio of the PBAT/PLA/CaSO4 composite sheet was increased by CaSO4 surface treatment with stearic acid, and the mechanical properties of the stretched film were improved.

Effect of Dimethyl 1,4-Cyclohexane Dicarboxylate on Mechanical Properties and Crystallization Behavior of Polytrimethylene Terephthalate Co-Polymer

김한나,박대선,염제성,장부경,김정철 한국고분자학회 2019 Macromolecular Research Vol.27 No.2

Dimethyl 1,4-cyclohexane dicarboxylate (DMCD) is formed as an impurity when dimethyl terephthalate (DMT) is manufactured from biomass. Because the boiling point of DMCD is similar to that of DMT, DMCD is known to add considerable cost to the separation and refinement. This prompted us to investigate the effect of the presence of varying amounts of DMCD on the physical properties of poly(trimethylene terephthalate) (PTT), which is manufactured from DMT. In the present study, a small amount of DMCD (1-5 mol% of DMT) was added when manufacturing PTT through the polycondensation of DMT and propanediol (PDO). The results of the analysis of the thermal properties indicated that the glass transition temperature and melting temperature showed a decreasing tendency as the DMCD content increased. The thermal stability increased by 25 °C compared to that of virgin PTT. The iso-thermal scanning analysis showed that the crystallization rate with 1 mol% of DMCD increased compared to that of virgin PTT, whereas the crystallization rate decreased with a higher DMCD content. The mechanical properties are noteworthy. The tensile strength and the tensile strain were simultaneously improved with the addition of DMCD, and the initial modulus remained nearly constant within the range of this experiment. Particularly, the tensile strength increased by a maximum of 15% (76.5 MPa) compared to that of virgin PTT. The physical properties of the PTT co-polyester significantly changed when the DMCD content was 2 mol%. Overall, the thermal properties remained similar, the crystallization rate increased, and the thermal stability and mechanical properties were significantly improved up to 2 mol%. Furthermore, the viscosity and crystal structure were examined by capillary rheometry and X-ray diffraction (XRD) to investigate the changes in these two properties. We concluded that the presence of bio-byproducts such as DMCD enhances the mechanical properties of PTT, such as the tensile strength and strain.