• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.4
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• pp.8-14
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• 2009

Characteristics of biodegradable polymers for mulching mat for seedling were investigated. The solvent solubility of polymers is highest in methylene chloride and chloroform. Tensile strength and breaking elongation of polymer dipped paper were increased to the 0.43-1.46 kN/m and the 0.03-0.26%, respectively. PLAs had showed lower glass transition temperature and melting point than those of polyester. As a result, PLA should be most suitable polymer for mulching mat manufacturing. After biodegradation of polymers by lipase, surface of polymers was change to more flat due to enzymatic degradation.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.643-649
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• 2017

Biodegradable enzymes such as lipase and proteinase can hydrolyze not only fatty acid esters and triglycerides, but also aliphatic polyesters. We measured the biodegradability that biodegradable enzymes have an important role in the degradation of natural aliphatic poly material such as PLA, corn starch, and polyethylene glycol in the natural environment. However, we investigated on the biodegradability of PLA, PLA and Polyethylene acrylate blended, and PLAcoPolyethylene polymerized with PLA graft copolymer Polyethylene glycol acrylate. When prepared biodegradable polymers. the Mechanical properties of them were measured on Biodegradability, thermal properties, real time in-situ electrical monitoring of polymers resin. Therefore BOD and biodegradation of PLAcoPolyethylene was graft copolymerized with PLA and polyethylene acrylate were measured at a lower rate than the other samples.

• Polymer(Korea)
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• v.26 no.2
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• pp.174-178
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• 2002

PLLA-POE-PLLA block copolymers were prepared using PLLA and POE with different compositions. Copolymers were obtained in high yield and the polydispersity of the copolymers was very narrow. A dispersed solution of 0.1 g/mL of PLLA-POE-PLLA copolymer was mixed with a dispersed solution of 0.1 g/mL of PDLA-POE-PDLA copolymer. Gel formation was observed from the mixed product obtained at the human body temperature of $37^{\circ}C$. The mixed product comprising PDLA-POE-PDLA and PLLA-POE-PLLA was found to have higher cloud points than that of PLLA-POE-PLLA copolymer. The cloud points decreased with increasing the concentration of the mixed copolymer dispersed solution.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.753-758
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• 2013

Molecular dynamics (MD) simulations have been used to study the diffusion behavior of small gas molecules ($CO_2$) in polyethylene terephthalate (PET)/polylactide (PLA) blends. The Flory-Huggins interaction parameters (${\chi}$) determined from the cohesive energy densities are smaller than the critical value of Flory-Huggins interaction parameters (${\chi}_{critical}$), and that indicates the good compatibility of PET/PLA blends. The diffusion coefficients of $CO_2$ are determined via MD simulations at 298 K. That the order of diffusion coefficients is correlated with the availably fractional free volume (FFV) of $CO_2$ in the PET/PLA blends means that the FFV plays a vital role in the diffusion behavior of $CO_2$ molecules in PET/PLA blends. The slopes of the log (MSD) as a function of log (t) are close to unity over the entire composition range of PET/PLA blends, which confirmes the feasibility of MD approach reaches the normal diffusion regime of $CO_2$ in PET/PLA blends.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.395-400
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• 2006

Polylactic acids polymer (PLA) was applied as an additive to improve the strength properties of handsheets prepared from three unbleached southern pine kraft pulps with different kappa number and an aspen bleached chemithermomechanical pulp (BCTMP). The results showed that PLA could greatly improve the tensile and burst strength of the pulp handsheets. Heat pressing effect was also important to enhance the strength properties. For unbleached kraft pulps, it was found that an appropriate amount of residual lignin in pulps had a positive effect on the handsheets strength improvement when adding PLA. The thickness of the handsheet did not change the PLA strengthening effect. In general, PLA effect on tear strength improvement could be neglected. However, it had a significant effect on the improvement of tear strength for the aspen BCTMP handsheets not containing sufficient amount of fines.

• Mycobiology
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• v.49 no.3
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• pp.285-293
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• 2021

Polylactic acid (PLA) and polycaprolactone (PCL) are commercially available bioplastics that are exploited worldwide, and both are biodegradable. The PLA and PCL polymer-degrading activity of 30 fungal strains that were isolated from terrestrial environments were screened based on the formation of a clear zone around fungal colonies on agar plates containing emulsified PLA or PCL. Among them, five strains yielded positive results of biodegradation. Strains Korean Agricultural Culture Collection (KACC) 83034BP and KNUF-20-PPH03 exhibited PCL degradation; two other strains, KACC 83035BP and KNUF-20-PDG05, degraded PLA; and the fifth strain, KACC 83036BP, biodegraded both tested plastics. Based on phylogenetic analyses using various combinations of the sequences of internal transcribed spacer (ITS) regions, RPB2, LSU, CAL, and b-TUB genes, the above-mentioned strains were identified as Apiotrichum porosum, Penicillium samsonianum, Talaromyces pinophilus, Purpureocillium lilacinum, and Fusicolla acetilerea, respectively. Based on our knowledge, this is the first report on (i) plastic biodegraders among Apiotrichum and Fusicolla species, (ii) the capability of T. pinophilus to degrade biodegradable plastics, (iii) the biodegradative activity of P. samsonianum against PCL, and (iv) the accurate identification of P. lilacinum as a PLA biodegrader. Further studies should be conducted to determine how the fungal species can be utilized in Korea.

• Korea-Australia Rheology Journal
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• v.19 no.3
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• pp.125-131
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• 2007

Biodegradable polymeric blends are expected to be widely used by industry due to their environmental friendliness and comparable mechanical and thermal properties. Poly (lactic acid) (PLA) and poly (butylene succinate) (PBS) are such biodegradable polymers which aim to replace commodity polymers in future applications. Since cost and brittleness of PLA is quite high, it is not economically feasible to use it alone for day to day use as a packaging material without blending. In this study, blends of PLA and PBS with various compositions were prepared by using a laboratory-scale twin-screw extruder at $180^{\circ}C$. Morphological, thermal, rheological and mechanical properties were investigated on the samples obtained by compression molding to explore suitability of these compositions for packaging applications. Morphology of the blends was investigated by scanning electron microscopy (SEM). Morphology showed a clear phase difference trend depending on blend composition. Modulated differential scanning calorimetry (MDSC) thermograms of the blends indicated that the glass transition temperature ($T_g$) of PLA did not change much with the addition of PBS, but analysis showed that for PLA/PBS blend of up to 80/20 composition there is partial miscibility between the two polymers. The tensile strength and modulus were measured by the Instron Universal Testing Machine. Tensile strength, modulus and percentage (%) elongation at break of the blends decreased with PBS content. However, tensile strength and modulus values of PLA/PBS blend for up to 80/20 composition nearly follow the mixing rule. Rheological results also show miscibility between the two polymers for PBS composition less than 20% by weight. PBS reduced the brittleness of PLA, thus making it a contender to replace plastics for packaging applications. This work found a partial miscibility between PBS and PLA by investigating thermal, mechanical and morphological properties.

• Journal of the Korean Wood Science and Technology
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• v.37 no.2
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• pp.155-163
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• 2009

This study examined the thermal stability of PLA-WF bio-composites. Wood flour (WF)-filled PLA bio-composites were reinforced with the flame retardants, Melamine pyrophosphate (MPP), resorcinol bis (diphenyl phosphate) (RDP) and zinc borate (ZB). The flame retardant was compounded with PLA and natural biodegradable filler. The thermal properties of the biodegradable polymer and bio-composites reinforced with the flame retardant were measured and analyzed by DSC, DMA and TGA. The results showed that the flame retardant-reinforced biodegradable bio-composite exhibited improved thermal properties.

• Korea-Australia Rheology Journal
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• v.17 no.2
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• pp.71-77
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• 2005

We investigated thermal, rheological, morphological and mechanical properties of a binary blend of poly(lactic acid) (PLA) and poly(butylene succinate adipate) (PBSA). The blends were extruded and their molded properties were examined. DSC thermograms of blends indicated that the thermal properties of PLA did not change noticeably with the amount of PBSA, but thermogravimetric analysis showed that thermal stability of the blends was lower than that of pure PLA and PBSA. Immiscibility was checked with thermal data. The rheological properties of the blends changed remarkably with composition. The tensile strength and modulus of blends decreased with PBSA content. Interestingly, however, the impact strength of PLA/PBSA (80/20) blend was seriously increased higher than the rule of mixture. Morphology of the blends showed a typical sea and island structure of immiscible blend. The effect of the blend composition on the biodegradation was also investigated. In the early stage of the degradation test, the highest rate was observed for the blend containing $80wt\%$ PBSA.

• Journal of Adhesion and Interface
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• v.9 no.4
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• pp.1-11
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• 2008

In the present study, kenaf fibers were treated with sodium hydroxide using soaking and ultrasonic methods prior to biocomposite processing, respectively. The effect of alkali treatment on the kenaf-PLA interfacial adhesion and mechanical and thermal characteristics of kenaf/poly(lactic acid) biocomposites was investigated in terms of their interfacial shear strength, flexural properties, dynamic mechanical properties and thermal stability and also microscopic observations of kenaf fibers and the composite fracture surfaces. As a result, use of both soaking and ultrasonic methods for treating kenaf fiber surfaces played a role in increasing the fiber-matrix adhesion and the mechanical properties of the biocomposites. Their characteristics depended not only on the fiber surface treatment method but also on the treatment condition like alkali concentration and treatment time.