• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.493-494
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• 2006

Chip breaker of cutting tool is an important feature to enhance cutting performance. Powder injection molding process was used to produce a triangular-shape cermet grooving insert which has three chip breakers. Attrition milled cermet powders were mixed with wax-based binder system in continuous twin screw extruder. Three-plate injection mold with slide cores was used to produce injection-molded parts. After molding, solvent and thermal debinding was carried out. Sintering was conducted in a batch furnace with a graphite heater. The sintered parts satisfy the requirements of dimensional tolerances and material properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.55-58
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• 1999

Crosslinked polyethylene/silane crosslinked polyethylene (XLPE/SXLPE) blends were prepared by a twin screw extruder and their water tree growing and electrical breakdown characteristics of XLPE were improved by the addition of SXLPE, when samples were crosslinked only by the thermorolysis of DCP (dicumyl perosxide). However, steam curing process was not good for water tree characteristics. It was also found that the rate of water tree growing of XLPE/SXLPE blend increased when the content of SXLPE was 50 %. AC breadown strength slightly increased by the addition of SXLPE to XLPE when samples were crosslinked only by the thermorolysis of DCP.

• The Korean Journal of Rheology
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• v.10 no.2
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• pp.57-64
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• 1998

A pultrusion resin impregnation (PRI) die, which has been developed recently in our laboratory, was used to pre-pare various composite system. The continuous fiber reinforced composites of glass fiber/polypropylene(GFPP) and glass fiber/polyamide 6 (GFPA) were first manufactured by means of the PRI die and then cut into chopped pellets of predet-ermined length. These pellets and either virgin or modified thermoplastic resin were melt-mixed by a twin screw extruder to prepare GF/PA/PP and GF/PA/PPMA system. The mechanical properties of these blends were investigated and discussed in terms of their morphological observations. These preliminary results revealed that this new impregnation die could be suc-cessfully applied to produce prepregs suitavle for the final shaping process.

• Journal of the Korean Society of Industry Convergence
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• v.13 no.2
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• pp.93-98
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• 2010

Polypropylene / montmorillonite / wood flour nanocomposites are melt-mixed by using a twin screw extruder. The montmorillonite is intercalated by the wood flour and the basal spacing of montmorillonite is increased with increasing the content of wood flour. The exfoliation constantly occurs by adding more than 10 wt.% of maleic anhydride-grafted polypropylene as the compatibilizer, which is used for improving the interfacial adhesion between matrix and filler. Also, the maleic anhydride-grafted polypropylene enhances the mechanical properties of the nanocomposites.

• Preventive Nutrition and Food Science
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• v.4 no.3
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• pp.159-162
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• 1999

The purpose of this research was to study the effects of initial moisture levels and extrusion temperatures on dietary fiber, nitrogen solubility index, available lysine, and the in vitro protein digestibility of extruded oat productes. The dehulled grains were ground in a Brabender quadrumat Senior mill and the coarse fraction, with higher crude protein, lipids and dietary fiber were conditioned on various mositre levels (15.5~25.5%) and extruded in a Brabender single-screw laboratory extruder. The extrudates showed a higher amount of soluble dietary fiber (8.14%) than in the raw material . However, the extrusion process affected the nutritional value of the protein due to a decrease in available lysine with increased temperature . The in vitro protein digestibility was unaffected by initial moisture levels and the extrusion temperatures examined.

• Elastomers and Composites
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• v.56 no.4
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• pp.217-222
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• 2021

In this study, random polypropylene (rPP) was compounded with two of monoglycerides, namely, glyceryl monolaurate (GML) and glyceryl monostearate (GMS), as antifogging agents to improve its antifogging performance. rPP film samples were prepared by a film-casting method using a three-roll casting machine after melt blending through a twin screw extruder. With an increase in the monoglyceride content, the melt flow index for rPP films with GML and GMS increased, and their yield strength decreased. The incorporation of GMS in rPP was proven to be more effective in improving its physical properties than was rPP with GML. When GML and GMS were separately added to the rPP film at contents of more than 1 phr and more than 5 phr, respectively, the film exhibited antifogging performance.

• Steel and Composite Structures
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• v.38 no.2
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• pp.177-187
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• 2021

The effect of nanoparticle volume fraction on the elastic properties of a polymer-based nanocomposite was experimentally investigated and the obtained results were compared with various existing theoretical models. The nanocomposite was consisted of high density polyethylene (HDPE) as polymeric matrix and 0, 0.5, 1 and 1.5 wt.% multi walled carbon nanotubes (MWCNTs) prepared using twin screw extruder and injection molding technique. Nanocomposite samples were molded in injection apparatus according to ASTM-D638 standard. Therefore, in addition to morphological investigations of the samples, tensile tests at ambient temperature were performed on each sample and stress-strain plots, elastic moduli, Poisson's ratios, and strain energies of volume units were extracted from primary strain test results. Tensile test results demonstrated that 1 wt.% nanoparticles presented the best reinforcement behavior in HDPE-MWCNT nanocomposites. Due to the agglomeration of nanoparticles at above 1 wt.%, Young's modulus, yielding stress, fracture stress, and fracture energy were decreased and Poisson's ratio and failure strain were increased.

• Elastomers and Composites
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• v.57 no.4
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• pp.147-156
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• 2022

In this study, we chose a flat die to optimize a general die geometry. The optimization was aimed at obtaining a uniform velocity distribution across the exit of the die. For the optimization, the input and output design parameters were randomly computed, and response surfaces were generated to obtain statistical data for the minimum and maximum sensitivities computed during optimization. Subsequently, object functions with constraints were numerically computed to obtain the minimum errors in the velocity difference (i.e., variable "Outp" in this study). Finally, we obtained the candidate optimized dataset. Note that the current numerical computations were simultaneously conducted for an entire extruder, i.e., screw plus die. The numerical outlet velocity distributions in the modified die geometry tended to be much more uniform than the conventional distributions in the current optimization processes for this specific flat die.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1128-1133
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• 1998

Extrusion cooking treatment was compared with autoclaving/cooling treatment for formation of enzyme resistant starch of high amylose corn starch (HACS). Effects of barrel temperature $(100^{\circ}C,\;120^{\circ}C,\;140^{\circ}C)$ and feed moisture content (25%, 35%, 45%) on extrusion processing in a co-rotating twin-screw extruder under fixed screw speed (100 rpm) were investigated by measuring enzyme resistant starch (RS) yield. RS yield were estimated by in-vitro pancreatin digestion method and enzymatic-gravimetric method using termamyl. Barrel temperature and yield of RS were negatively correlated and feed moisture content and yield of RS was positively correlated as determined by in-vitro pancreatin method. The highest yield (38.4%) of RS was obtained from HACS extrudate processed at the barrel temperature of $100^{\circ}C$ and the feed moisture content of 45%, while the yield of RS by 5 times of autoclaving/cooling was 25%. The yield of RS by in vitro pancreatin digestion method was 20.7% with high amylose corn starch and 8.2% with ordinary corn starch (CS), respectively, under the same extrusion condition (barrel temperature $120^{\circ}C$, feed moisture content 35%). At the same condition, the yields of RS by enzyme-gravimetric method were 14.6% with HACS and 6.8% with CS, respectively. The yield of RS increased during the storage at $4^{\circ}C$ for 4 weeks and the highest yield (60%) was obtained by the storage of HACS extrudates extruded at $100^{\circ}C$ and 45% feed moisture content.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.23-28
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• 2015

Lacquer sap extracted from lacquer trees exhibits good thermal stabilities and antimicrobial properties. To apply these superior properties to functional packaging, polyurushiol (YPUOH) powders were prepared and blended into LDPE (low density polyethylene) to prepare three different LDPE/YPUOH composite films via a twin screw extruder system. Their morphology, thermal and antimicrobial properties as well as barrier properties of the LDPE/YPUOH composite films were thoroughly investigated to find out applicablities of the films as functional packaging materials. Although the interfacial interaction between LDPE and YPUOH was relatively weak, LDPE/YPUOH composite films exhibited good dispersion of YPUOH in LDPE, resulting in the enhanced thermal stability with YPUOH loading. Due to the good antibacterial property of as-prepared YPUOH, LDPE/YUOH composite films also showed an excellent antibacterial activity (R) of 99.9% against E. coli. Furthermore, the moisture barrier property of LDPE/YPUOH composite films increased with increasing YPUOH contents. Incorporating the relatively low amount of YPUOH in LDPE resulted in the apparent enhancement in thermal stabilities, antibacterial and moisture barrier properties, which made them promising candidates as a functional filler for packaging materials.