• Elastomers and Composites
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• v.46 no.4
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• pp.335-342
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• 2011

The virgin and recycled polyethylene composites with various ratio of fly ash were manufactured by using a fully intermeshing co-rotating twin screw extruder for the reuse of fly ash from power plant and post-consumed polyethylene. Fly ash were blended with virgin HDPE and recycled polyethylene at the weight fraction of 0 to 40 wt.%. Mechanical properties such as yield strength, abrasion resistance, and slow crack resistance were measured with ISO and ASTM standards. The experimental results for the various composites showed that the elongation at break and the yield stress of the composites decreased with increasing fly ash contents. Generally, the abrasion resistance of PEs decreased with increasing sandpaper grits but the abrasion resistance of the composites increased with fly ash content at finer abrasive surface. The slow crack growth resistance of virgin HDPE, recycled JRPE and the JRPE composite showed higher slow crack growth resistance up to 50% of load at notch depth of 20% and 30%, but KRPE and the KRPE composite showed much lower resistance than virgin HDPE, JRPE and the JRPE composite. Time to break, measured with NCLS test method, of all PEs and the composites satisfies the regulation of Korean Industrial Specification for sewer pipe and support application.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.497-501
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• 1999

The changes of properties were studied for the polypropylene(PP)/Nylon6 blends containing different kinds of compatibilizer made by either reactive extrusion of solution reaction. The compatibilizers were PP grafted with maleic anhydride (MAH) made by reactive extrusion and solution reaction. The grafted MAH contents were 0.3 wt %, and 2.7 wt %, respectively. The composition of the PP/nylon6 blend was fixed at 75/25 by weight. Blending was carried out with twin-screw extruder (L/D=30, ${\psi}=30$) at 300 rpm. As the content of PP-g-MAH was increased, the crystallization peak of Nylon6 decreased gradually then finally disappeared. Disappearance of crystallization peak of Nylon6 was mostly affected by grafted MAH content rather than the preparation method and the amount of compatibilizer. The portion of Nylon6 that could not crystallize in its normal crystallization temperature crystallized together with PP at the crystallization temperature of PP. So called concurrent crystallization was observed. Meanwhile two more peaks were observed during heating cycle. One was exothermic peak at $193^{\circ}C$ near to crystallization temperature of Nylon6, the other was endothermic peak at $215^{\circ}C$ that was $5^{\circ}C$ lower than normal endothermic peak of Nylon6. To analyze the peaks, nylon6 was annealed in the differential scanning calorimeter. As a result, the peak at $193^{\circ}C$ was crystallization peak of imperfect crystalline of Nylon6 and the other peak at $215^{\circ}C$ was melting peak of imperfect crystalline of nylon6.

• Analytical Science and Technology
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• v.25 no.5
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• pp.273-283
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• 2012

Phthalate plasticizers are regulated by RoHS, REACH and CPSC as hazardous substances. Responding to these international environmental restrictions, we developed ABS certified reference material (CRM) for determination of phthalate plasticizers such as DMP, DEP, DBP, BBP, DEHP and DnOP. The candidate material has been made with ABS resin widely used in electric and electronic products and 6 kinds of phthalate plasticizers. The making of the material involved a series of processes like extruding, cooling, pelletizing, and drying using twin screw extruder. Then it has been certified according to ISO Guide 35. Using isotope dilution-gas chromatography/mass spectrometry (ID-GC/MS), homogeneity, short-term stability, and long-term stability were evaluated. The certified values were determined by using primary reference material (PRM) of KRISS for traceability. From now on, we will provide ABS CRM to national and international companies and research institutes after certification as certified reference material and registering on COMAR (code of reference material).

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.73-79
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• 2017

Maleic anhydride (MAH) grafted polypropylene (PP-g-MAH) copolymers were prepared by changing MAH and styrene monomer (SM) content, using a twin screw extruder at $190^{\circ}C$. The grafting degree was measured by non-aqueous back titration method. The grafting degree of PP-g-MAH-SM copolymer was higher than that of PP-g-MAH at the same MAH content. PP-g-MAH-SM/kenaf fiber (KF) composites were also prepared by using a PP-g-MAH as a matrix at $200^{\circ}C$ and the KF content was fixed at 20 wt%. Based on the degradation temperature investigated by TGA, the thermal stability of PP-g-MAH-SM/KF composites was more enhanced than that of PP-g-MAH only. Mechanical properties of the composites were also improved when MAH and SM applied together. The adhesion degree between the copolymer and KF was confirmed by both SEM pictures of the fractured surface and contact angles.

• Clean Technology
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• v.19 no.4
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• pp.401-409
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• 2013

BBiodegradable polymers have attracted great attention because of the increased environmental pollution by waste plastics. In this study, PLA (polylactic acid)/Clay-20 (Cloisite 20) and PLA (polylactic acid)/PBS (poly(butylene succinate)/Clay-20 (Cloisite 20) nanocomposites were manufactured in a twin-screw extruder. Specimens for mechanical properties of PLA/Clay-20 and PLA/PBS (90/10)/Clay-20 nanocomposites were prepared by injection molding. Thermal, mechanical, morphological and raman spectral properties of two nanocomposites were investigated by differential scanning calorimetry (DSC), tensile tester, scanning electron microscopy (SEM) and raman-microscope spectrophotometer, respectively. In addition, hydrolytic degradation properties of two nanocomposites were investigated by hydrolytic degradation test. It was confirmed that the crystallinity of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposite was increased with increasing Clay-20 content and the Clay-20 is miscible with PLA and PLA/PBS resin from DSC and SEM results. Tensile strength of two nanocomposites was decreased, but thier elongation, impact strength, tensile modulus and flexural modulus were increased with an increase of Clay-20 content. The impact strength of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposites with 5 wt% of Clay-20 content was increased above twice than that of pure PLA and PLA/PBS (90/10). The hydrolytic degradation rate of PLA/Clay-20 nanocomposite with 3 wt% of Clay-20 content was accelerated about twice than that of pure PLA. The reason is that degradation may occur in the PLA and Clay-20 interface easily because of hydrophilic property of organic Clay-20. It was confirmed that a proper amount of Clay-20 can improve the mechanical properties of PLA and can control biodegradable property of PLA.

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

• Resources Recycling
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• v.24 no.2
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• pp.36-45
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• 2015

In this study, various sizes of waste ground rubber tire (WGRT) were devulcanized by a single screw extruder equipped with a sonicator in front of the die, and waste PP and devulcanized waste ground rubber tire (DWGRT) composites were prepared by an intermeshing co-rotating twin screw extruder. The crosslink density and percent devulcanization of WGRT and DWGRT for 40, 80 and 140 meshes were calculated. The mechanical properties of the composites were compared with each other. The effect of SEBS-g-MA as a compatibilizer was investigated on mechanical properties of both waste PP/WGRT and waste PP/DWGRT composites. The crosslink density was decreased with decreasing the WGRT size. On the other hand, the percent devulcanization was increased by adding the smaller size of WGRT. Also, tensile strength, impact strength and elongation at break of the composite with DWGRT were higher than those with WGRT. Especially, mechanical properties of the composites were significantly increased by adding the smaller size of WGRT and DWGRT. Addition of SEBS-g-MA into both waste PP/(D)WGRT composites exhibited better impact strength and elongation at break than the composites themselves.

• Elastomers and Composites
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• v.41 no.2
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• pp.97-107
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• 2006

The recycled polyethylene composites with various ratio of ground waste tire powder were manufactured by using a fully intermeshing co-rotating twin screw extruder for the reuse of waste tire scrap. In this investigation, the ground waste tire powders (GWTP) were blended with virgin HDPE and recycled polyethylene in the weight ratio of 0 to 50 wt.%. Mechanical properties such as tensile strength, elongation at break and impact strength were measured by using ASTM standard. The experimental results for the various composite showed that the tensile strength of composites decreased with increasing GWTP ratio, while elongation at break increased with the amounts of GWTP. On the other hand, the impact strength for the three kinds of composites showed maximum at the 30 wt.% of GWTP and then decreased. Morphology of the fracture surface tends to be rough with increasing waste tire powder content. Rheological properties were investigated by measuring the shear viscosity against shear rates and softening temperatures. They showed that melt viscosity of rubber composites in this study subsequently increased with increasing GWTP content as a result of increase of flow resistance against external stress and followed a Power-law behavior.

• Polymer(Korea)
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• v.37 no.4
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• pp.494-499
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• 2013

Modified polypropylene (m-PP) was fabricated by furfuryl sulphide (FS) as branching agent and m-PP/nano-filler composites were prepared with silicate and multi-walled carbon nanotube (MWCNT), using a twin screw extruder. The chemical structures and thermal properties of the m-PP were investigated by FTIR and DSC. The chemical structure of the m-PP was confirmed by the existence of =C-H stretching peak of the branching agent at 3100 $cm^{-1}$. There was no district change in melting temperature in case of m-PP, but a certain increase in crystallization temperature was notified and the increase was in the range of $10-20^{\circ}C$. The rheological properties, filler dispersion and foaming behaviors of the m-PP/nano-filler composites were investigated by dynamic rheometer, X-ray diffractometer (XRD) and scanning/transmission electron microscope (SEM/TEM). m-PP/nano-filler composites showed a high complex viscosity at a low frequency, an increase in melt elasticity, and a high shear thinning effect. Compared to pure PP, m-PP and m-PP/nano-filler composites were sufficient to enhance the foaming behavior.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.90-95
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• 2014

Nylon66 extrudates as a function of the extrusion number were prepared by a twin screw extruder. Chemical structures, thermal properties, melt index, crystal structures, mechanical properties such as the tensile strength, elongation at break and impact strength, and rheological property were measured by FT-IR, $^1H$-NMR, melt indexer, DSC, TGA, XRD, universal tensile tester, Izod impact tester, and rheometer. FT-IR and $^1H$-NMR characterizations indicated that the number of extrusions did not affect the chemical structure. The decrease in the molecular weight was checked by the melt index of extrudates. There were no effects of the thermal history on the melting and degradation temperature. The tensile and impact strength and modulus were found to be similar, regardless of the number of extrusions, but the elongation decreased significantly. The complex viscosity of extrudates at low frequencies decreased with the extrusion number. No structural changes after extrusion were confirmed from the fact that there was no change in the slope and shape of G'-G" plot.