Jun-Seok Yeo

Preparation and characteristics of polypropylene-graft-maleic anhydride anchored micro-fibriled cellulose: its composites with polypropylene

The surface modification of micro-fibriled cellulose (MFC) was carried out through the hydrolysis–condensation reaction using (3-aminopropyl)triethoxysilane (APS) and then was subsequently treated with polypropylene-graft-maleic anhydride (MAPP) to give desired MAPP-anchored MFC (MAPP-a-MFC). The confirmation of surface modification for the pristine MFCs was characterized by FTIR, EDX, and XPS measurements. The polypropylene (PP) composites with MAPP-a-MFC were prepared via typical melt-mixing method. The effects of MAPP-a-MFC on the physical properties of the PP composites were investigated. From the results of mechanical properties, thermal behaviors, and the morphology of the composites, it was found that there was an improved interfacial adhesion between the MAPP-a-MFC and PP matrix in the composites.

Preparation and Physical Properties of Poly(lactic acid) Bio-Composites using Surface Modified Microfibriled Celluloses

The surface modification of microfibriled cellulose (MFC) was carried out through the hydrolysis–condensation reaction using (3-aminopropyl)triethoxysilane (APS) and 3-glycidyloxypropyltriethoxysilane (GPS) and then the modified cellulose was compounded with bio-degradable poly(lactic acid) (PLA). Also, pristine MFC was compounded with PLA as a control groups. The confirmation of surface modification for the pristine MFC was characterized by FT-IR and SEM/ EDX. The thermal and mechanical properties of the PLA/MFC composites depended on the content of MFC and the type of silane coupling agents. From the thermal, morphological and mechanical behaviors of the PLA/MFC composites, it was found that GPS-MFC was more successful to improve the interface adhesion between PLA matrix and the surface of MFC than that of APS-MFC.

Effects of Chemically Surface Modified Lignin on Flexural Strength and Fracture Toughness for Lignin/Unsaturated Polyester Resin Composites

The lignin granule modified by allyltrimethoxy silane (VPS) was used to fabricate unsaturated polyester resin (UPR) composites as a reinforcing filler. The chemical surface modification of the pristine lignin granule was analyzed by FTIR and SEM/EDX. UPR composites reinforced by pristine lignin granule were prepared as the control samples and UPR composites reinforced by VPS-Lignin were prepared to study their flexural strength and fracture toughness behavior depending on the filler content. VPS-Lignin/UPR composites showed the better performance than of the pristine Lignin/ UPR composites in the mechanical properties (flexural strength and flexural modulus). And, the high values of the critical stress intensity factor (KIC) and the critical strain energy release rate (GIC) for VPS-Lignin/UPR composites implied the enhanced interfacial adhesion between UPR matrix and VPS-Lignin filler in the composites, which induced their enhanced fracture toughness.

Synthesis of UV-Curable PDMS-Modified Urethane Acrylate Oligomer and Physical Properties of the Cured Film

Hydroxypropyl terminated PDMS was synthesized by the hydrosilylation reaction with allyl alcohol in the presence of Karstedts catalyst. And them, an one-pot reaction with HDI isocyanurate trimer and hydroxyethyl methacrylate was conducted to give a silicone-modified urethane acrylate oligomer (PUA oligomer) having 9000 g/mol, weight average molecular weight. The synthesized PUA oligomer was characterized by using FT-IR and GPC. The UV-curable coatings were prepared by PUA oligomer blending with a reactive monomer (phenylthioethyl acrylate) under the different mole ratios. It was found that the refractive index of cured film increased when the reactive monomer was added but there was no relationship between the refractive index and amount of reactive monomer. Also, their transmittance for cured films was not change as increasing the content of reactive monomer.