• Macromolecular Research
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• v.10 no.3
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• pp.135-139
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• 2002

Blends of the linear bisphenol-A polycarbonate (L-PC) and randomly branched bisphenol-A polycarbonate (Br-PC), prepared by co-rotating twin screw extrusion, were investigated using differential scanning calorimetry (DSC), sag resistance time tester, extensional rheometry, and advanced rheometric expansion system (ARES). From the DSC results, the glass transition temperature (T$_{g}$) of the L-PC/Br-PC blend was increased with the increase of Br-PC in the blend, and the blend showed a single T$_{g}$, which suggests a miscible blend. The sag resistance time of the L-PC/Br-PC blend was increased with the increase of Br-PC in the blends. From the results of rheological measurements of the L-PC/Br-PC blends, the extensional viscosity and the complex viscosity of the blends were found to increase with the increase of Br-PC in the blends. The increase of extensional viscosity and complex viscosity was related with the increase of sag resistance time with the Br-PC in the L-PC/Br-PC blends.nds.

• Macromolecular Research
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• v.17 no.6
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• pp.417-423
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• 2009

The effects of maleic anhydride-grafted polypropylene (PP-g-MAH) addition on polypropylene (PP) and poly(acrylonitrile-butadiene-styrene) (ABS) blends were studied. Blends of PP/ABS (70/30, wt%) with PP-g-MAH were prepared by a twin-screw extruder. From the results of mechanical testing, the impact, tensile and flexural strengths of the blends were maximized at a PP-g-MAH content 3 phr. The increased mechanical strength of the blends with the PP-g-MAH addition was attributed to the compatibilizing effect of the PP and ABS blends. In the morphological studies, the droplet size of ABS was minimized (6.6 ${\mu}m$) at a PP-g-MAH content of 3 phr. From the rheological examination, the complex viscosity was maximized at a PP-g-MAH content of 3 phr. These mechanical, morphological and rheological results indicated that the compatibility of the PP/ABS (70/30) blends is increased with PP-g-MAH addition to an optimum blend at a PP-g-MAH content of 3 phr.

• Macromolecular Research
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• v.11 no.5
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• pp.357-367
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• 2003

The linear low density polyethylene (LLDPE)/zeolite composite using novel inorganic filler, zeolite, is prepared by a conventional compounding procedure using a twin-screw extruder. The observed scanning electron microscopic (SEM) morphology shows a good dispersion and adhesion of zeolite in the LLDPE matrix. The mechanical properties in terms of the Young's modulus, the yield stress, the impact strength, and the elongation at break were enhanced with a successive increment of zeolite content up to 40 wt%. The X-ray diffraction measurement is of supportive for the improved mechanical properties and the complex melt viscosity is as well. Upon applying a certain level of strain on the composites, the dewetting, the air hole formation and its growth are characterized. The dewetting originates around the filler particles at low strain and induces elliptical micropores upon further stretching. The microporosity such as the aspect ratio, the number and the total area of the air holes is also characterized. Thus, the composites loaded 40 % zeolite and 300 % elongation may be applicable for breathable microporous films with improved modulus, impact and yield stress, elongation at break, microporosity and air hole properties.

• Advances in materials Research
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• v.5 no.2
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• pp.121-130
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• 2016

In an attempt to reach a balance of performances in homo-polypropylene based system, the effects of single and hybrid reinforcements inclusions comprising calcium carbonate nanoparticles (2, 4 and 6 phc) and glass fibers (10 wt.%) on the mechanical and thermal properties were investigated. Different samples were prepared by employing twin-screw extruder and injection molding machine. In morphological studies, the uniform distribution of glass fibers in PP matrix, relative adhesion between glass fibers and polymer, and existence of nanoparticles in polymer matrix were observed. $PP/CaCO_3$ (6 phc) as compared to pure PP and PP/GF had superior tensile and flexural strengths, impact resistance and deformation temperature under load (DTUL). $PP/GF/CaCO_3$ (6 phc) composite displayed comparable tensile and flexural strengths and impact resistance to neat PP, while its tensile and flexural moduli and deformation temperature under load (DTUL) were 436%, 99% and $26^{\circ}C$greater respectively. The maximum impact resistance was observed in $PP/CaCO_3$(6 phc). The highest DTUL was perceived in PP hybrid nanocomposite containing 10 wt.% glass fiber and 4 phc $CaCO_3$ nanoparticle.

• Polymer(Korea)
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• v.24 no.3
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• pp.366-373
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• 2000

In this study, the PPS/ABS blend system was investigated in order to collectively identify the relationship among blend morphology, chemical compatibilization and thermal property. ABS resin was chemically modified by the incorporation of maleic anhydride through reactive extrusion for enhanced compatibilization, and PPS, ABS and the modified ABS were blend by a sing twin screw extruder. The effect of chemical modification of ABS on the morphological, mechanical, and thermal properities of the resulting blend was examined. A strong interaction was observed between PPS and MABS by optical microsopy as well as scanning electron microscopy, exhibiting a well-dispersed morphological feature. The PPS/MABS blend showing a single glass transition temperature was observed in dynamic mechanical analysis, demonstrating a pseudo-homogeneous phase morphology induced by chemical compatibilization. PPS/MABS blend also exhibited an enhanced thermal stability and heat distortion temperature compared with modified PPS/ABS blend.

• Macromolecular Research
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• v.8 no.2
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• pp.95-101
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• 2000

Clay/poly(styrene-co-acrylonitrile) copolymer (SAN) hybrids have been prepared by simple meltmixing of two components, SAN and organophilic clays with a twin screw extruder. Effects of intercalant on the dispersibility of silicate layers in clay-dispersed nanocomposite were studied by using five different organophilic clays modified with the intercalants of different chemical structures and different fractions of intercalant. The dispersibility of 10-$\AA$-thick silicate layers of clay in the hybrid was investigated by using an X-ray diffractometer and a transmission electron microscope. It was found that if the fraction of intercalant in the organophilic clay becomes too high, SAN is difficult to intercalate into the inter-gallery of silicate layers in the hybrid prepared at 180$\^{C}$, and thus the hybrid shows poor dispersibility of silicate layers. The flexural modulus of the hybrid increases as the dispersibility of silicate layers in the hybrid increases.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.284-288
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• 2022

Polypropylene (PP) powder/cellulose nanofibers (CNF) 1 wt% slurry composites were prepared by filtering their suspension under reduced pressure and dried them in an oven followed by the use of a twin screw extruder. PP modified with side branches and polar groups was used. The side branches and polar groups were introduced into PP by using divinylbenzene and maleic anhydride (MAH), respectively. As a result of examining the dispersibility of CNF and the physical properties of the composite, it was confirmed that the composite prepared from PP powder/CNF 1 wt% slurry showed equal or higher levels in tensile and flexural strength as compared with those using the composite prepared from CNF powder.

• Composites Research
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• v.19 no.3
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• pp.15-22
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• 2006

In this study, we prepared glass fiber reinforced polypropylene composites using Brabender twin-screw extruder. Compatibilizer, polypropylene-based maleic anhydride (PP-g-MAH), was used to increase the molecular interaction between polypropylene matrix and glass fiber and to enhance melt processability. We also measured the shear and uniaxial elongational behaviors of glass-fiber reinforced composites in the absence or presence of compatibilizer. The effects of compatibilizer and fiber loading on the viscoelastic behaviors were examined. It was fuund that the PP-g-MAH compatibilizer improved the fluidity and increased the molecular bonding of composite melts in shear flow. Transient elongational viscosity was increased with fiber loadings in uniaxial elongational flow However, it was decreased with increasing elongational rates because of microscale shear flow between fibers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.306-310
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• 2005

The comparison in release rate constant and properties of extracts from extruded raw ginseng and extruded white ginseng was conducted to apply extrusion process for manufacturing of released ginseng tea bag. Dry raw ginseng and white ginseng powder were extruded at 20∼30% moisture content and 200∼300 rpm by using an experimental twin-screw extruder. Browness and redness (both indicated the releasing of saponin and ginsenosides) were increased with the increase in the screw speed and the decrease of moisture content. Crude saponin and water solubility index (WSI) of both ginseng also share the same behaviour against the level of screw speed and moisture content, as well as browness and redness. The particle size effects of extruded raw ginseng at 20% and 28% moisture content on absorbance of released extract at 260 up to 560 nm, WSI, and water absorption index were determined. While particle size decreased from 800∼1000 nm to 200∼500 nm, absorbance and WSI are decreased. Absorbance and WSI shown increasing level while moisture content was decreased. In conclusion, the formation of pores by expansion and disruption of cell wall in extrusion cooking were obviously responsible to increase the amount of released extract of extruded ginseng and its WSI as well. The extrusion process turns out be the efficient process for manufacturing of commercial ginseng tea product than those of other thermal processes.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.1
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• pp.34-46
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• 2019

This paper provides the numerical results for the self-propulsion performance in waves of a car ferry vessel with damage in one of its twin-screw propulsion systems without flooding the engine room. The numerical simulations were carried out according to the Safe Return to Port (SRtP) regulation made by the Lloyd's register, where the regulation requires that damaged passenger ships should have an ability to return to port with a speed of 6 knots in a Beaufort 8 sea condition. For the validation of the present numerical analysis study, the resistance performance and the self-propulsion performance of the car ferry in intact and damaged conditions in calm water were calculated, which showed a satisfactory agreement with the model test results of Korea Research Institute of Ship and Ocean engineering (KRISO). Finally, the numerical simulation of self-propulsion performance in waves of the damaged car ferry ship was carried out for a normal sea state and for a Beaufort 8 sea state, respectively. The estimated average Brake Horse Power (BHP) for keeping the damaged car ferry ship advancing at a speed of 6 knots in a Beaufort 8 sea state reached about 47% of BHP at MCR condition or about 56% of BHP at NCR condition of the engine determined at the design state. In conclusion, it can be noted that the engine power of the damaged car ferry ship in single propulsion condition is sufficient to satisfy the SRtP requirement.