• Polymer(Korea)
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• v.39 no.1
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• pp.64-70
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• 2015

Thermally expandable microcapsules (TEMs) can be expanded upon heating since the activation energy of liquid hydrocarbon at the core of the TEMs increased at high temperature. Due to this property, TEMs are widely used in the industry as blowing agents or light-weight fillers. In this article, chemical blowing agent and TEM were used for making polypropylene (PP) foams, and their mechanical properties were compared. Physical properties (tensile strength, impact strength etc.) of PP foams decreased with increasing the amount of blowing agents while weight of specimen decreased. However, PP foam produced with TEMs showed higher impact strength than the one with a chemical blowing agent. In order to figure out the difference of impact strength, the morphology of PP foamed was investigated. Expanding properties of TEM can be controlled by changing core back distance.

• 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.

• Journal of Adhesion and Interface
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• v.3 no.4
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• pp.1-9
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• 2002

The main goal of this study was to analyze the effect of process additives, i.e. maleated polypropylene (MAPP), and nucleating agent on the viscoelastic properties of different types of extruded polypropylene-wood plastic composites manufactured from either PP homopolymer, high crystallinity PP or PP impact copolymer using dynamic mechanical thermal analysis. And also, the esterification reaction between wood flour and maleated polypropylene, and its role in determining the mechanical properties of wood flour-polypropylene composites was investigated. The wood plastic composites were manufactured using 60% pine wood flour and 40% polypropylene on a Davis-Standard $Woodtruder^{TM}$. Dynamic mechanical thermal properties, polymer damping peaks(than ${\delta}$), storage modulus (E') and loss modulus (E") were measured using a dynamic mechanical thermal analyzer. XPS (X-ray Photoelectron Spectroscopy), also known as ESCA (Electron Spectroscopy for Chemical Analysis) study of wood flour treated with MAPP was performed to obtain information on the chemical nature of wood fiber before and after treatment. To analyze the effect of frequency on the dynamic mechanical properties of the various composites, DMA tests were performed over a temperature range of -20 to $100^{\circ}C$, at four different frequencies (1, 5, 10 and 25 Hz), and at a heating rate of $5^{\circ}C/min$. From these results, the activation energy of the various composite was measured using an Arrhenius relationship to investigate the effect of maleated PP and nucleating agent on the measurement of the interphase between the wood and plastic of the extruded polypropylene wood plastic composites.

• Journal of Environmental Science International
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• v.17 no.11
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• pp.1255-1263
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• 2008

The efficiency of PP-g-AA and PP-g-St nonwoven fabric synthesized by photoinduced polymerization as an adsorbent for removal $NH_3-N$ from waste water was evaluated. The results evidently indicate that the adsorption capacities of $NH_3-N$ onto PP-g-AA nonwoven fabric were extremely superior to those onto sulfonated PP-g-St nonwoven fabric, PK and zeolite. PP-g-AA nonwoven fabric showed the maximum adsorption capacity of $NH_3-N$ at the degree of grafting of 80 wt.%. The adsorption behaviour of $NH_3-N$ onto PP-g-AA and sulfonated PP-g-St nonwoven fabric was controlled by an ion exchange reaction, and tended to be similar to both trends of Langmiur and Freundlish isotherm. Futhermore, PP-g-AA non-woven fabric could be regenerated more than 5 times by a simple washing with 0.1N HCl with no decrease of adsorption capacity and no degradation of physical properties. Also sulfonated PP-g-St nonwoven fabric could be regenerated by washing with 0.1N ${H_2}{O_4}$. However, their regeneration efficiency was significantly low because grafting layer acted as functional radical for adsorption was continuously desquamated in the adsorption or regeneration processes, which resulted in decrease of adsorption capacity and weight of adsorbent. All results obtained from this study indicate that the $NH_3-N$ removal capacity of PP-g-AA non-woven fabric was extremely superior to those of PP-g-St non-woven fabric, PK and zeolite.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.138-145
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• 1998

Synergistic effect and characteristics of coliquefaction with Alaskan subbituminous coal and polypropylene (PP) were investigated in a tubing-bomb reactor. Coliquefaction results showed considerable synergistic effect on conversions for various coal/PP compositions and tetralin addition. Therefore, coliquefactions conversions at 430$^{\circ}$C and 450$^{\circ}$C with (coal 2 g+PP 2g) and 4 ml tetralin appeared 20.0 and 11.6 per cent higher respectively compared to the conversion of (coal+tetralin) and (PP+tetralin) liquefactions. According to gas chromatographic analyses, hydrogen was not needed during PP liquefactions. On the other hand, 0.70~0.83 part of tetralin per part of coal was converted into naphthalene by donoring hydrogen to free radicals during liquefaction. Also, extraction results by decalin proved that synergistic effect of coliquefaction were mainly due to PP decomposition catalysed be coal.

• Composites Research
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• v.26 no.1
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• pp.1-6
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• 2013

CNT-polypropylene (PP) composites were compounded by solvent dispersion method with uniform dispersion by using twin screw extruder. Damage sensing effects based on conductive carbon nanotubes (CNT) were evaluated to monitor the internal damage of CNT-PP composites using electrical resistance measurement. Mechanical and interfacial properties of CNT-PP composites were investigated and compared with neat PP. The mechanical properties of PP matrix were improved after adding CNT, because of the reinforcing effect of CNT fillers. In order to monitor the internal damage of CNT-PP composite, the change in electrical resistance of the composites was measured under fatigue loading and bending tests. CNT fillers exhibited good sensing under electrical resistance measurements. It is shown that CNT-PP composites with low CNT contents allow identifying critical cyclic loading, which are found to be accompanied with the internal failure.

• Polymer(Korea)
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• v.38 no.2
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• pp.250-256
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• 2014

Polypropylene (PP) composites containing conductive multi-walled carbon nanotube (MWNT) and stainless steel short fiber (SSF) were manufactured using a twin screw extruder and characterized their surface resistivity and mechanical properties in this work. Surface resistivity measurements showed that the percolation threshold appeared at a lower MWNT loading when a small amount of SSF was added to PP/MWNT composites. Tensile modulus and strength of the composites increased but elongation-at-break decreased greatly compared to pure PP. Also, the effects of MWNT and SSF on storage modulus and tan ${\delta}$ from dynamic mechanical analysis for the composites were examined, and the morphologies of fractured surface and the fillers were observed using a scanning electron microscope.

• Textile Coloration and Finishing
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• v.28 no.2
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• pp.101-108
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• 2016

Polypropylene(PP)/multiwalled carbon nanotubes(MWCNT) nanocomposites films and PP/poly(vinyl alcohol)/CNT nanocomposites films were prepared through melt mixing method by the extruder. The PP/CNT nanocomposites films, which contain CNT of a variable content, were prepared for the first time and research on a appropriate content of the CNT on the PP/CNT nanocomposites films was conducted. The effects of take-up speed of the extruder on the mechanical and chemical properties of the PP/CNT and PP/PVA/CNT nanocomposites film were studied. Field emission scanning electron microscope(FE-SEM) was used to examine the surface morphology and the DSC measurement and tensile test were conducted. It was found that the properties decreased when take-up speed was increased.

• Polymer(Korea)
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• v.26 no.4
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• pp.508-515
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• 2002

The effects of the crosslinking caused by irradiation dose, molecular weights of the foaming materials, and various foaming processes on the foam structure of the polypropylene (PP) were investigated. The maximum gel content of the PP was 48% when the sheet was irradiated with 3.2 Mrad. This high gel content improved the cell structures by providing high thermal stability. The increase of both the gel content and structural development were stopped at the irradiation dose exceeding 3.2 Mrad. The increase of the molecular weights served to help produce a foam with particularly fine and even cell structures, along with improved thermal stability as well.

• Nuclear Engineering and Technology
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• v.45 no.2
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• pp.223-236
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• 2013

In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber.