• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.78-83
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• 2012

In this study, some experimental results of the peroxide-degradation process of polypropylene(PP) in a co-rotating twin-screw extruder to produce controlled rheology polypropylene(CRPP) are presented. The peroxide was dicumyl peroxide(DCP) and the concentration of DCP was in the range 0-0.3 wt%. It was found that the rheological properties of PP change significantly during reactive extrusion. Melt flow index(MFI) increased with DCP concentration. Intrinsic viscosity decreases with increasing DCP concentration. From dynamic rheological data, number average molecular weight(Mn), weight average molecular weight(Mn) and molecular weight distribution(MWD) were calculated. Results indicated that Mw decreases and MWD becomes narrower with increasing peroxide concentration. Especially, particle size distribution of CRPP decreases with increasing DCP concentration by chemical powdering process, and anti-slip floor paint, CRPP(DCP 0.2 wt%) powder by 10phr was friction coefficient 2.15 ${\mu}$, abrasion resistance 511.18%.

• Polymer(Korea)
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• v.33 no.4
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• pp.358-363
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• 2009

Maleic anhydride-grafted polypropylene has been widely used to improve the interfacial interaction between the components in PP/polar polymer blends and PP/filler composites and to maximize the physical properties and thermal properties. In this paper. the maleic anhydride (MAH)-grafted polypropylene (co-PP) was fabricated through reactive extrusion process with di-cumyl peroxide (DCP) as an initiator. The grafting degree of MAH depending on the contents of DCP and MAH was investigated by FT-IR spectra and chemical titration. The grafting degree increased with increasing MAH concentration and also showed maximum value at 0.06 wt% of DCP concentration. Melt flow index (MFI) of the grafted copolymer was increased with increasing the contents of MAH. The DSC and TGA analysis data indicate the melting temperature and thermal degradation of PP depending on the grafting degree of MAH.

• Food Engineering Progress
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• v.15 no.4
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• pp.404-412
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• 2011

The purpose of this study is to prepare extruded rice flours suitable for baking rice cookies. The extruded rice flours were prepared at 100 and 130$^{\circ}C$ temperature and 25 and 27% moisture content in a co-rotating twin screw extruder. The rice extrudates were dried at 100$^{\circ}C$ for 18 hr and subsequently ground into the fine flour. Characteristics of the extruded rice flours were examined by rapid visco analysis, hydration property analysis, differential scanning calorimetry (DSC), and in vitro digestion test. Water absorption, solubility, and swelling power of all extruded rice flours were higher than those of native rice flour. DSC analysis showed that native rice flour had a peak at about 65$^{\circ}C$ while all extruded rice flours did not show any peaks since they were already gelatinized during the extrusion proess. Viscosity of the extruded rice flours decreased with increasing temperature and lowering moisture content in the extrusion proess. The extruded rice flours prepared at 130$^{\circ}C$ exhibited lower viscosity than those prepared at 100$^{\circ}C$. The operating temperature of the extrusion proess was critical for the starch digestion in vitro. The extruded rice flours prepared at 130$^{\circ}C$ showed a rapid decrease in digestible starch content while an increased level of slowly digestible starch content was observed compared to those treated at 100$^{\circ}C$ in the extruder. Cookies were prepared with a mixture of wheat flour and extruded rice flours at the ratio of 7 to 3. The cookies made with the extruded rice flours had lower spread factor and darker yellow color than those prepared with wheat flour only. Hardness of the extruded rice flour-added cookies was similar to that of the wheat flour cookie whereas their overall acceptance was better. Therefore the rice cookies partially supplemented with extruded rice flours may have a potential as early childhood foods which require soft texture and allergy reduction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.228-234
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• 2016

The aim of this study was to develop pharmaceutical dosage forms with a bi-phasic drug using a double extrusion approach. Hot melt extrusion was performed using a co-rotating twin-screw extruder. The. 1st melt extrusion was performed using polymer with a relatively higher Tg, such as HPMC and the 2nd melt extrudate was obtained using the 1st extrudate and polymers with a lower Tg, such as HPMC-AS and PEO. In addition, the formulation with all the content in the same proportion as the double extudate was produced using single extrusion for comparison. Physical characterization was performed on the formulations employing differential scanning calorimetry (DSC). In vitro release tests were studied using a USP Type-I apparatus at $37{\pm}0.5^{\circ}C$ and 100 rpm. The similarity factor (f2) was also used to check the difference statistically. The DSC results indicated that the crystallinity of ibuprofen was changed to an amorphous state after extrusion in both double and single melt extrusion. Double melt extrudate with ibuprofen showed the desired release in acidic media (pH 1.2) in the first two hours and basic (pH 6.8) during six hours. Double melt extrudate with glimepiride showed faster release in 60 min of over 80%, whereas the single extrudate with glimepiride showed retarded release due to the interaction with HPMC. The similarity factor(f2) value was 28.5, which demonstrates that there were different drug release behavior between the double and single extrusion. Consequently, the double melt extrudated formulation was robust and gave the desired drug release pattern.