• Advances in materials Research
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• v.6 no.4
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• pp.329-341
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• 2017

The challenge of replacing conventional plastics with biodegradable composite materials has attracted much attention in product design, particularly in the tensile-related areas of application. In this study, fibres extracted from oil palm empty fruit bunch (EFB) were treated and utilized in reinforcing polyester matrix by hand lay-up technique. The effect of fibre loading and combined influence of alkali and silane treatments on porosity and water absorption parameters, and its correlation with the tensile behaviour of composites was analyzed. The results showed that tensile strength decreased whilst modulus of elasticity, water absorption and porosity parameters increased with increasing fibre loading. The composites of treated oil palm EFB fibre exhibited improved values of 2.47 MPa to 3.78 MPa for tensile strength; 1.75 MPa to 2.04 MPa for modulus of elasticity; 3.43% to 1.68% for porosity and 3.51% to 3.12% for water absorption at respective 10 wt.% fibre loadings. A correlation between porosity and water absorption with tensile behavior of composites of oil palm EFB fibre and positive effect of fibre treatment was established, which clearly demonstrate a connection between processing and physical properties with tensile behavior of fibre composites. Accordingly, a further exploitation of economic significance of oil palm EFB fibres composites in areas of low-to-medium tensile strength application is inferred.

• Polymer(Korea)
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• v.34 no.4
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• pp.381-385
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• 2010

Aiphatic diester monomer, 3-[(benzyloxycarbonylamino)butyl]-1,4-dioxane-2,5-dione (BABD), was synthesized with the N-$\varepsilon$-benzyloxy-carbonyl-L-lysine as starting material. This monomer was synthesized to add the functionality to poly(lactic acid)s. BABD unit was successfully incorporated into the PLLA chain which was confirmed by $^1H$ NMR. The copolymer composition could be controlled by the feed ratios of monomer. The $M_n$ of this resultant polymer is expected to reach high molecular weight after the purification of monomer and optimization of polymerization time, though the polymer showed relatively low degree of polymerization ($M_n$＝3300). The copolymer is expected to possess the enhanced hydrophilicity and the possibility of chemical modification on amino group.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.263-263
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• 2006

Poly (ethylene glycol)(PEG) - Poly (${\varepsilon}-caprolactone(CL)$) - Poly (D,L lactide(LA) (PCLA-PEG-PCLA) was synthesized by ring-opening polymerization to form temperature sensitive hydrogel triblock copolymer. The triblock copolymer was acrylated by acryloyl chloride. ${\beta}-amino$ ester was used as a pH sensitive moiety, in this study ${\beta}$- amino ester obtained from 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine, it have pKb around 6.6. pH/temperature sensitive penta-block copolymer (PAE-PCL-PEG-PCL-PAE) was synthesized by addition polymerization from acrylated triblock copolymer, 1,4-butandiol diacrylate, and 4, 4' trimethylene dipiperidine. Their physicochemical properties of triblock and penta-block copolymers were characterized by $^1H-NMR$ spectroscopy and gel permeation spectroscopy. Sol-gel phase transition behavior of PAE-PCL-PEG-PCL-PAE block copolymers were investigated by remains stable method. Aqueous media of the penta-block copolymer (at 20 wt%) changed from a sol phase at pH 6.4 and $10^{\circ}C$ to a gel phase at pH 7.4 and $37^{\circ}C$. The sol-gel transition properties of these block copolymers are influenced by the hydrophobic/hydrophilic balance of the copolymers, block length, hydrophobicity, stereo-regularity of the hydrophobic of the block copolymer, and the ionization of the pH function groups in the copolymer depended on the changing of environmental pH, respectively. The degradation and the stabilization at pH 7.4 and $37^{\circ}C$, and the stabilization at pH 6.4 and $10^{\circ}C,\;5^{\circ}C,\;0^{\circ}C$, of the gel were determined. The results of toxicity experiment show that the penta block copolymer can be used for injection drug delivery system. The sol?gel transition of this block copolymer also study by in vitro test ($200{\mu}l$ aqueous solution at 20wt% polymer was injected to mouse). Insulin loading and releasing by in vitro test was investigated, the results showed that insulin can loading easily into polymer matrix and release time is around 14-16days. The PAE-PCL-PEG-PCL-PAE can be used as biomaterial for drug, protein, gene loading and delivery.

• Polymer(Korea)
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• v.38 no.6
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• pp.815-819
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• 2014

Scaffolds of tissue engineering should be biocompatible and biodegradable for cell attachment, proliferation and differentiation. In the various scaffold fabrication, 3D printing technique can make the three dimensional scaffold with interconnected pores for cell ingrowth. Polycaprolactone (PCL) is biodegradable polyester with a low melting temperature and has been approved by the Food and Drug Administration (FDA). In this study, PCL scaffold was fabricated by 3D bioprinting system and surface modification of PCL scaffold was controlled by NaOH treatment. Morphological change and wetability of NaOH-treated scaffold were observed by SEM and contact angle measurement system. The remnant of PCL treated with NaOH was measured by ATR-FTIR. In vitro study of scaffolds was evaluated with WST-1 and ALP activity assay. NaOH treatment of PCL scaffolds increased surface roughness, hydrophilicity, cell proliferation and osteogenic differentiation. These results indicate that NaOH-treated PCL scaffold made by 3D bioprinting has tissue engineered potential for the development of biocompatible material.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.889-898
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• 1994

Melt blends of copolyesterethylene(CPEE) and ethylene vinylacetate copolymer(EVA) with 15% vinylacetate content were prepared in the ratio of 0 to 100% CPEE with 10% interval for the purpose of obtaining useful biodegradable polymer system. Miscibility behavior of melt blend samples has been studied by observing the melting temperature change and cold crystallization temperature with differential scanning calorimetry. From the results of thermal analysis, it was shown that each 10% blend composition of CPEE and EVA had the partially miscibility. Useful compatibility has been observed in all blend composition except the samples of 50~80 % CPEE composition from the mechanical property study. Compatibility of these blend has been also observed with scanning electron microscopy. Biodegradability of CPEE/EVA blends has been evaluated by observing the change of specimen with Image analyzer before and after the inoculation with specific microorganism.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.399-404
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• 2003

Aliphatic polyester, especially poly(butylene adipate)(PBA), is quite biodegradable and one of the most promising polymer materials to be commercialized. Bis(4-hydroxybutyl) adipate (BHBA) formation stage is the first principal process in the production of PBA from adipic acid (AA) and 1,4-butane diol (BD). In this study, we investigated for the effective production of Bis(4-hydroxybutyl) adipate (BHBA), effects of molar ratio of adipic acid (AA) to 1,4-butane diol (BD), catalyst (tetrabutyl titanate, TBT) concentration, and temperature on the reaction rate of esterification between AA and BD were investigated. Initial reaction rate of the esterification decreased with increasing molar ratio of AA to BD and reaction temperature, whereas reaction constant increased with increase in catalyst-concentration. Activation energy values for catalyzed and uncatalyzed esterifications were 198.5 and 94.8 kJ/mol, respectively.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.970-976
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• 1996

An ester-carbonate copolymer was synthesized, in which carbonate was inserted into a biodegradable aliphatic polyester, poly(butylene succinate) (PBS), to modify its mechanical properties. The synthesis was carried out by condensation reactions in two steps. In the first step, oligo(butylene succinate) was prepared by the reaction of succinic acid with 1,4-butanediol (BD). In the second step, it was reacted with oligohexamethylenecarbonate diol (OHMCG) to prepare the ester-carbonate copolymer. Titanium(IV) isopropoxide (TIP) was used as a catalyst for the reaction. The structure of the copolymer was confirmed by FT-IR and $^1H$-NMR and the thermal behavior and mechanical properties were investigated by differential scanning calorimetry (DSC) and universal testing machine (UTM), respectively. It was found that optimum amount of the catalyst for the formation of high molecular weight copolymer was 1wt% for succinic acid. When the BD:OHMCG is in the range 149:1~249:1, the copolymer with high viscosity was obtained. As the OHMCG content was increased, melting temperature ($T_m$) of the copolymer was decreased. When BD:OHMCG is 149:1, the copolymer showed a increase in ultimate strain by two times and the slight decrease in modulus compared to those of PBS.