• Sim-seong Yeon-gu
• /
• v.38 no.2
• /
• pp.305-307
• /
• 2023

• Sim-seong Yeon-gu
• /
• v.38 no.2
• /
• pp.308-310
• /
• 2023

• Polymer(Korea)
• /
• v.38 no.5
• /
• pp.613-619
• /
• 2014

The polypropylene/polyamide elastomer (PP/PAE) blends were prepared by melt mixing. PP and PAE in PP/ PAE were immiscible completely. The size of PAE domains was large and the clear gap in the interface between PP and PAE existed, which did not meet the conditions enhancing toughness of polymers by elastomer. Therefore, maleic anhydride grafted polypropylene (MP) was used to improve the miscibility between PP and PAE. The miscibility between PP and PAE was improved and the size of dispersed phase PAE decreased by introducing MP. The crystallization of PP became easier by introducing PAE as a nucleating agent. With the increase of PAE content, the melt-crystallization temperatures of PP components in PP/PAE/MP blends increased gradually. The melt-crystallization of the polytetramethylene oxide segment of PAE component in PP/PAE blends were hampered by PP component. In addition, PAE can enhance significantly the toughness of PP, and the tensile strength and modulus did not decrease.

• Polymer(Korea)
• /
• v.38 no.5
• /
• pp.566-572
• /
• 2014

Maleic anhydride (MAH) grafted polypropylenes (PP) (MAH-g-PP) were prepared by changing MAH content and styrene monomer (SM)/MAH mole ratio with different type PP, using a twin screw extruder. The types of PP were isotatic PP (iPP), block PP (bPP), and random PP (rPP) and dicumyl peroxide (DCP) was used as an initiator. The graft degree of MAH was confirmed by the existence of carbonyl group (C=O) stretching peak at $3100cm^{-1}$ of FTIR spectrum. Thermal properties of MAH-g-PP and PP/MAH-g-PP/pulp composites were investigated by DSC and TGA. There was no district change in thermal properties of PP/MAH-g-PP/pulp composites. Based on tensile properties and SEM pictures for fractured surface of PP/MAH-g-PP/pulp composites, MAH-g-rPP was the best as the compatibilizer and optimum formulation was MAH content of 1.0 wt%, SM/MAH mole ratio of 1.0, and melt index (MI) of 25 g/10 min. The rheological properties of the composites were investigated by a dynamic rheometer. The complex viscosity, shear thinning effect, and water uptake incresed with pulp content.

• Proceedings of the Korean Fiber Society Conference
• /
• 1996.04a
• /
• pp.64-68
• /
• 1996

PP-EVOH(poly(vinyl alchol-co-ethylene)) blends were prepared by the mixing of polypropylene and poly(vinyl alcohol-co-ethylene) containing 38mol% of ethylene units (EVOH38) at melt state above PP melting temperature. The materials were characterized by using dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and contact angle measurement to detemine the glass transition, meltin, decomposition temperatures, and wettability respectively. From the results, PP-EVOH(poly(vinyl alcohol-co-ethylene)) blends exgibits partial miscibility.

• BMB Reports
• /
• v.39 no.6
• /
• pp.671-676
• /
• 2006

The holoenzyme of protein phosphatase (PP) from tulip petals was purified by using hydrophobic interaction, anion exchange and microcystin affinity chromatography to analyze activity towards p-nitrophenyl phosphate (p-NPP). The catalytic subunit of PP was released from its endogenous regulatory subunits by ethanol precipitation and further purified. Both preparations were characterized by immunological and biochemical approaches to be PP2A. On SDS-PAGE, the final purified holoenzyme preparation showed three protein bands estimated at 38, 65, and 75 kDa while the free catalytic subunit preparation showed only the 38 kDa protein. In both preparations, the 38 kDa protein was identified immunologically as the catalytic subunit of PP2A by using a monoclonal antibody against the PP2A catalytic subunit. The final 623- and 748-fold purified holoenzyme and the free catalytic preparations, respectively, exhibited high sensitivity to inhibition by 1 nM okadaic acid when activity was measured with p-NPP. The holoenzyme displayed higher stimulation in the presence of ammonium sulfate than the free catalytic subunit did by protamine, thereby suggesting different enzymatic behaviors.

• Polymer(Korea)
• /
• v.38 no.2
• /
• pp.129-137
• /
• 2014

In this study, the melt-mixing condition was optimized first to maximize the physical properties of a wood plastic composite (WPC) with recycled polypropylene (PP) and the effects of recycled PP content on the physical properties of the WPC were investigated. Mechanical properties of the WPC were measured by UTM and an izod impact tester and thermal properties were investigated by DSC, TGA and DMA. Fracture surfaces of the WPC were investigated by SEM. The optimized mixing condition of WPC with 50 wt% recycled PP of total PP was melt-mixing at $170^{\circ}C$ for 15 min at 60 rpm. With increasing the content of the recycled PP, the water absorption characteristics of the WPC increased and the thermal and mechanical properties decreased. However, the following was concluded from the analysis of all the physical properties; it was possible adding the recycled PP up to 50 wt% of total PP without a significant decrease in the performance of the WPC.

• The Korea Journal of Herbology
• /
• v.38 no.1
• /
• pp.31-43
• /
• 2023

Objective : Alcoholic liver disease (ALD) is caused by excess alcohol intake. In the liver, alcohol breakdown results formation of toxic byproducts that lead to damage to tissue. This study is to investigate the therapeutic effects of Paeoniae Radix Alba and Puerariae Radix combination (PP) on ALD. Methods : PP was analyzed for polyphenolic compounds and free radical scavenging activity. ALD mouse model was induced by feeding ethanol and water (Control), silymarin (50 mg/kg), low-dose (PP: 100 mg/kg) or high-dose (PP: 200 mg/kg) was orally administrated to ALD mice for 14 days. The serum was assessed with levels of AST, ALT, total bilirubin, total cholesterol, and triglyceride. Liver tissues were evaluated for ROS levels, degree of liver damage and protein expression. Results : The 3:1 (Paeoniae Radix Alba:Puerariae Radix) ratio showed the best antioxidant values for the experiment. In ALD model, levels of AST, ALT, total bilirubin, total cholesterol, and triglyceride were significantly increased in the Control and the levels were decreased by treatment of PP. In addition, increased ROS, ONOO^- and MDA levels in the Control were reduced in the PP groups. Western blot analysis figured out that proteins related to ROS and cholesterol metabolism were higher in ALD than in PP-treated ALD. Antioxidant enzyme expression was low in the control group and increased by PP treatment. Conclusion : Our results suggest that PP has the potential to be a medicine in ALD in terms of regulating oxidative stress and adjusting lipid metabolism.

• Journal of Korean Society for Quality Management
• /
• v.38 no.2
• /
• pp.171-179
• /
• 2010

Pearn et al.(2002) supposed the $C_{pp}$ multiple process performance analysis chart. This chart displays multiple processes with the process variation and process departure on one single chart. But, this chart can not display the distribution of the process variation and process departure and is inappropriate for processes with non-normal distributions. With bootstrapping method, we can display the distribution of the process variation and process departure on the $C_{pp}$ multiple process performance analysis chart.

• Elastomers and Composites
• /
• v.38 no.2
• /
• pp.122-127
• /
• 2003

Compounding, using such thermoplastic elastomer as styrene-ethylene-butadiene-styrene (SEBS) blended with polypropylene(PP), oil, and other ingredients, was studied to develop a new material with excellent impact resistance and resilience for the replacement of environmentally toxic PVC sheet. Hardness decreased linearly with oil content in the SEBS/oil blend, and the tensile strength increased with PP content whereas elongation showed no effects over 50 phr of PP in SEBS/oil/PP blend. In the practical SEBS composition, proposed to replace the PVC sheet material, tensile and tear strength, as well as hardness, increased proportionally with PP content, while melt index decreased.