• Korea-Australia Rheology Journal
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• 제19권3호
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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.

• Korean Journal of Materials Research
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• 제30권12호
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• pp.650-654
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• 2020

A combination of Polycarbonate (PC) material and Polymethylmethacrylate (PMMA), fabricated using an injection molding machine, has been investigated to determine its advantages, as studied in Ref. 1). This paper aims to investigate the optimization of PMMA/PC blend for both tensile yield strength and impact strength. Furthermore, interaction effects of process conditions on mechanical properties including tensile yield strength and impact strength of PMMA/PC blend by injection molding process are interpreted in this study. Tensile and impact specimens are designed following ASTM, type V, and are fabricated by injection molding process. The processing conditions such as melt temperature, mold temperature, packing pressure, and cooling time are applied; each factor has three levels. As a result, in comparison with optimization of separated responses, mechanical properties of PMMA/PC are found to decrease when optimizing both tensile and impact strengths simultaneously. The melt temperature is found to be the most significant interaction parameter with the mold temperature and packing pressure. In addition, there is more interaction between the mold temperature and cooling time. This investigation provides a useful understanding of the control of injection molding processing of polymer blends in optical application.

• Membrane Journal
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• 제28권2호
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• pp.113-120
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• 2018

Global warming due to indiscriminate carbon dioxide emissions has a profound impact on human life by causing abnormal climate change and ecosystem destruction. As a way to reduce carbon dioxide emissions, in this study, we presented a polymeric membrane prepared by blending a self-crosslinkable P(GMA-g-PPG)-co-POEM (SP) copolymer and commercial polymer polyvinylpyrrolidone (PVP). As the content of PVP increased, it was observed that the gas permeance decreased and $CO_2/N_2$ selectivity increased. At 30 wt% PVP content, the $CO_2$ permeance of the membrane decreased from 72.9 GPU of pure SP polymer to 12.6 GPU, while $CO_2/N_2$ selectivity improved by 79% from 28.1 to 50.4. It results from the hydrogen bonding between the SP copolymer and PVP, leading to more compact structure of the polymer chains, which was confirmed by FT-IR, TGA, XRD and SEM analysis. Therefore, we suggest that the permeance and selectivity of the membranes can be easily adjusted as desired by controlling the PVP content in the SP/PVP polymer blend.

• Membrane Journal
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• 제25권6호
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• pp.496-502
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• 2015

Facilitated transport is one of the possible solutions to simultaneously improve permeability and selectivity, which is challenging in conventional polymer-based membranes. Olefin/paraffin separation using facilitated transport membrane has received much attention as an alternative solution to the conventional distillation process. Herein, we report olefin separation composite membranes based on the polymer blends containing $AgBF_4/Al(NO_3)_3$ mixed salts. Free radical polymerization process was used to synthesize an amphiphilic graft copolymer of poly(dimethyl siloxane)-graft- poly(ethylene glycol) methyl ether methacrylate (PDMS-g-POEM). In addition, poly(ethylene oxide) (PEO) was introduced to the PDMS-g-POEM graft copolymer to form polymer blends with various ratios. The propylene/propane mixed-gas selectivity and permeance reached up to 5.6 and 10.05 GPU, respectively, when the PEO loading was 70 wt% in polymer blend. The improvement of olefin separation performance was attributed to the olefin facilitating silver ions as well as the highly permeable blend matrix. The stabilization of silver ions in the composite membrane was achieved through the introduction of $Al(NO_3)_3$ which suppressed the reduction of silver ions to silver particles.

• Polymer(Korea)
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• 제24권1호
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• pp.82-89
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• 2000

The blood compatibilities of PU/PVA polymer blends with different mixing ratios were evaluated using various methods, such as fibrinogen adsorption, plasma recalcification time, platelet adhesion, whole blood clotting time, and complement activation. In addition, PVA on the surface of the polymer blends was crosslinked by glutaraldehyde to restrain the mobility of PVA molecules for characterizing the effect of PVA in the polymer blends on blood compatibility. The fibrinogen adsorption on the polymer blends decreased with the increase of PVA amount in the polymer blends. The plasma recalcification times of the polymer blends with 10-50 wt% PVA were longer than those of PU, PVA, and polymer blends with higher amount of PVA. The morphological changes and adhesion of platelets on the polymer blends with 30-50 wt% PVA were less than those on the other materials. The blood clotting times and complement activation on the polymer blends with 30-50 wt% PVA were reduced, compared to the other materials. On the other hand, the blood compatibility of the crosslinked polymer blends was relatively decreased, compared to the non-crosslinked ones. According to these experimental results, the blood compatibility of the polymer blends with 30-50 wt% PVA was better than that of the other materials and such a blood compatibility of the polymer blends might be related to the mobility of PVA molecules on the surface.

• Polymer(Korea)
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• 제32권3호
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• pp.251-255
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• 2008

This study suggested antistatic material which can increase anti-static properties and mechanical strength by mixing polystyrene for conveying electronic stuffs with metal salt and ester compound as a anti-static agent. We studied about mechanical, thermal and electrical characteristics by changing the contents of MAH of poly(styrene-co-maleic anhydride), compatibilizer. As the result of measuring residue space charge of the blends of HIPS(75)/TPU(25)/poly(styrene-co-maleic anhydride)(MAH weight ratio : 25, 32, 43.5 wt%), we could find small residue charge in the blend which MAH(25 wt%) was added and it showed the highest values in tensile strength. Additionally we found out the material to which compatibilizer was added kept better anti-static properties than one to which compatibilizer was not added. In the event we could confirm that the adding of PS-co-MAH enables two polymers were mixed well when HIPS/TPU was blended and anti-static agent made easier dissipative in the blend.

• Polymer(Korea)
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• 제26권3호
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• pp.316-325
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• 2002

The deformation and coalescence behaviors of immiscible LDPE/PS blends (86.5/13.5 vol%) prepared by internal mixer were studied using rheometer and scanning electron microscope. The fine droplets coagulated at initial stage of mixing, and deformed fiber at large strain. The critical capillary number was calculated according to the empirical equation of De Bruijn and it was 0.95, the local capillary number was 3.867. The polymer blends were annealed at $200^{\circ}C$ for various time to investigate morphological change of polymer blends. The maximum size of droplet after annealing at $200^{\circ}C$ was found at ${\gamma}$=1798, and there was destruction of the morphology at 15 minutes of annealing time. The viscosity of matrix was critical to determine a coalescence of droplet.

• Polymer(Korea)
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• 제34권3호
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• pp.237-241
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• 2010

Mechanical characteristics and chemical resistance have been investigated for PC/PBT blends. The changes in mechanical performance of PC/PBT blends was monitored during the treatment with both the PC thinner and general-purpose thinner to figure out the chemical resistance. The PC thinner greatly affected the mechanical properties of PC/PBT blends compared with general-purpose thinner. In the case of PC thinner treatment, the mechanical performance was improved with increased PC content at lower PC content ranges, say below 50%. However the mechanical performance was dropped rapidly at higher PC content ranges due to poor chemical resistance of PC. Transparent pure PC specimen became opaque after chemical treatment with PC thinner, and this can be interpreted by solvent-induced crystallization.

• Polymer(Korea)
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• 제24권6호
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• pp.810-819
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• 2000

Poly(p-hydroxybenzoate) (PHB)/poly(ethylene terephthalate) (PET) 8/2 thermotropic liquid crystalline copolyester, poly(ethylene 2,6-naphthalate) (PEN), and PET ternary blend was spun to fiber by melt spinninB process, and tensile properties of the fibers were measured. The matrix of the fibers, PET and PEN, were dissolved in ο-chlorophenol at 55$^{\circ}C$ for 2 hours, and the liquid crystalline polymer fibrils were observed using a scanning electron microscope. Halpin-Tsai equation for modulus calculation of short fiber reinforced composite and the rule of mixture for continuous reinforcement composite were modified, and the tensile modulus were calculated and compared with experimental modulus. To minimize difference between the theoretical and the experimental moduli, dimensionless viscosity constant (K) was given and used to modify two equations. The theoretical tensile modulus using the newly modified equations presentel a similar to the experimental tensile modulus of composite, and the modified equations presented a unique way to determine the tensile modulus of the liquid crystalline polymer reinforced thermoplastic composites.

• Applied Chemistry for Engineering
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• 제24권1호
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• pp.104-111
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• 2013

Poymer blends of two degradable aliphatic polyesters, relatively expensive material polylactic acid (PLA) and relatively inexpensive material poly(butylene adipate-co-terephthalate) (PBAT), were used in this study. Three different kinds of modifiers were used with various amounts. Diisocyanate type methylenediphenyl 4,4'-diisocyanate (MDI) and hexamethylene diisocyanate (HDI) were used as modifiers and epoxy type coupling agents also used. The melt flow index (MFI) and dynamic viscoelasticity of various compositions of PLA/PBAT blends were studied. The mechanical property and morphology with respect to the fracture surface of PLA/PBAT blends were also investigated using tensile test and field emission scanning electronic microscopy, respectively. These tests were also used to verify the compatibility of PLA/PBAT and the effect of mechanical properties due to the use of modifiers. Tensile properties of PLA/PBAT blends modified with HDI were improved remarkably.