• Polymer(Korea)
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• v.39 no.1
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• pp.130-135
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• 2015

Cellulose has attracted much attention as potential reinforcements in green composites. In this study, polypropylene (PP)/cellulose composites were prepared by melt-blending followed by compression molding. To improve interfacial bonding between PP and cellulose, maleic anhydride-grafted polypropylene (MAPP) was used. Mechanical properties of the PP/cellulose composites were investigated by UTM and izod impact tester. Thermal properties of the PP/cellulose composites were investigated by TGA and DSC. SEM images for the fracture surfaces of the composites showed that the MAPP was effective in improving PP/cellulose interfacial bonding. Tensile strength and modulus of the composite were maxima when MAPP content, based on cellulose content, was 3 wt%. With increasing cellulose content, the impact strength of the composites decreased but the tensile strength and modulus increased.

• Polymer(Korea)
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• v.29 no.3
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• pp.248-252
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• 2005

PP/MMT nanocomposites having a various compositions were prepared by melt blending with a twin screw extruder. In this study, maleic anhydride-grafted PP (MAH-g-PP) was used as a compatibilizer in order to assist the exfoliation or hen in the pp matrix. from the results or x-ray diffraction (XRD) and transmission electron microscope (TEM) measurements for the nanocomposites, we confirmed that MMT was exfoliated. PPM nanocomposites have shown good flame retardancy by synergistic effect between MMT and flame retardant. The mechanical and thermal properties of the nanocomposites showed significant enhancement compared with those of neat PP, The excellent flame retardancy of the PP/MMT nanocomposites, UL94 V-0 value, was successfully obtained with reduced amount of the flame retardant.

• Korea-Australia Rheology Journal
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• v.11 no.3
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• pp.255-263
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• 1999

Blends of two thermotropic liquid crystalline polymers, HX2000 and Vectra A950, were prepared by melt blending. Effects of transesterification on these blends are investigated by comparing properties of the blends with and without the addition of an inhibitor, in terms of blend miscibility and rheology. Both the uninhibited and inhibited blends are found to be largely immiscible with very limited miscibility in HX2000-rich phase. No strong evidence indicates the occurrence of transesterification in the blends in the solid state. Dynamic rheological behaviour, such as shear storage modulus (G') and shear loss modulus (G") as a function of frequency, of the blends are interpreted by a three-zone model. HX2000 shows terminal-zone and plateau-zone behaviour, whilst Vectra A950 shows plateau-zone and transition-zone behaviour. The un- inhibited blends show plateau-zone behaviour up to 50% Vectra A950 content and the inhibited blends show plateau-zone behaviour up to 60% Vectra A950 content. Compositional dependence of the complex viscosities of the uninhibited and inhibited blends displayed positive deviations from additivity, which is a characteristic feature for the immiscible thermoplastic blends. When under steady shear, both the uninhibited and inhibited blends show shear thinning behaviour and their viscosities decrease monotonically with the addition of Vectra A950. Compositional dependence of the steady shear viscosities of the two sets of blends displayed negative deviations from additivity and the uninhibited blends were more viscous than the inhibited blends for the full composition range. Although limited agreement with the Cox-Merz rule is found for the inhibited blends, these two sets of blends, in general, do not follow the rule due to their liquid crystalline order and two-phase morphology. Despite being immiscible blends, transesterification, such as polymerization, in the blends might occur during the rheological characterization, supported by the facts that uninhibited blends show HX2000-dominant behaviour at lower Vectra A950 content and are more viscous than the inhibited blends. The addition of transesterification inhibitor in such blends is advised if only physical mixing is desired.ired.

• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.278-286
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• 2007

As a part of enhancing the performance of wood-plastic composites (WPC), polypropylene (PP)/ nanoclay (NC)/ wood flour (WF) nanocomposites were prepared using melt blending and injection molding process to evaluate their thermal stability. Thermogravimetric analysis (TGA) was employed to investigate thermal degradation kinetics of the nanocomposites both dynamic and isothermal conditions. Dynamic scans of the TGA showed an increased thermal stability of the nanocomposites at moderate wood flour concentrations (up to 20 phr, percentage based on hundred percent resin) while it decreased with the addition of 30 phr wood flour. The activation energy $(E_a)$ of thermal degradation of nanocomposites increased when nanoclay was added and the concentration of wood flour increased. Different equations were used to evaluate isothermal degradation kinetics using the rate of thermal degradation of the composites, expressed as weight loss (%) from their isothermal TGA curves. Degradation occurred at faster rate in the initial stages of about 60 min., and then proceeded in a gradual manner. However, nanocomposites with wood flour of 30 phr heated at $300^{\circ}C$ showed a drastic difference in their degradation behavior, and reached almost a complete decomposition after 40 min. of the isothermal heating. The degree of decomposition was greater at higher temperatures, and the residual weight of isothermal degradation of nanocomposites greatly varied from about 10 to 90%, depending on isothermal temperatures. The isothermal degradation of nanocomposites also increased their thermal stability with the addition of 1 phr nanoclay and of wood flour up to 20 phr. But, the degradation of PP100/NC1/MAPP3/WF30 nanocomposites with 30 phr wood flour occurs at a faster rate compared to those of the others, indicating a decrease in their thermal stability.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.379-383
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• 1977

Since the organophilic bentonite disperses well in polymer matrix, a composite material of polymer and bentonite was studied for its mechanical properties. To increase the degree of dispersion and the bond in forces to the polymer matrix, bentonite, encapsulated by imidazoline, was used as a filler. Polyethylene powder of particle size of 100 mesh was used, and organophilic bentonite, so-called bentone, whose particle size was 250 mesh was also used in this experiment. V-type mixer was used for mixing and Banbury mixer was used for melt-blending. The sample specimen were made by heating the mixture in the plate press, and the specimen were formed as a sheet, exactly the same as the mold on the plate. Tensile strength, bending strength and compressive strength were studied specially. Tensile strength, elongation rate, bending strength and bending rate at constant pressure were decreased as the filler content increased. Compressive strength was increased as the filler content increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4673-4678
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• 2011

In this paper, studies on a mixing characteristic and viscosity measurement of polymer/graphite composites for a bipolar plate of the polymer electrolyte membrane fuel cell were presented. Since the materials for the bipolar plate should be electrically conductive, contents of solid graphite in the composite are very high. As a consequence, a viscosity of the polymer/graphite composite used for the bipolar plate is very high and the measurement of the viscosity is difficult. Viscosity measurements of the polymer/graphite composites were not possible because pressure drops were continuously fluctuated during the viscosity measurements when a conventional capillary die was used. After the die design was optimized, the steady state pressure drop could be achieved, but the viscosity thus measured was not reproducible. After many trials with different experimental techniques, it was found that melt blending of the grinded powder mixtures of both PET and graphite provides reproducible viscosity measurements and electric conductivities of the polymer/graphite composites.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1136-1140
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• 1999

Melt blends of polymide 6(PA6) and polypropylene grafted maleic anhydride(PP-g-MA) were prepared to study the influence of chemical reaction between the two polymer components. The tensile, flexural, izod impact, dynamic mechanical properties and phase structure were investigated for this blend system. Tensile strength and modulus of the blends showed synergetic effect upon blending of two polymer components. Flexural properties maintained the value of numerical mean calculated from the weight ratio of two components. Also, notched izod impact strengths showed maximum in th PA6/PP-g-MA 50/50 wt % blend. From the change of tan ${\delta}$ observed, we confirmed the increase of miscibility in this blend system by chemical reaction between PA6 and PP-g-MA. Blends of good impact resistance could be obtained when the PP-g-MA particles of $2{\mu}m$ was dispersed in the PA6 matrix.

• Polymer(Korea)
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• v.36 no.5
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• pp.573-578
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• 2012

In general, most physical properties of wood/polyvinyl chloride (PVC) composites are lower than those of corresponding neat PVC resin because of poor interfacial adhesion between the hydrophilic wood flour and hydrophobic PVC. Therefore, in this study, we treated wood flour with three aminosilanes to improve wood/PVC interfacial adhesion strength, and eco-friendly wood/PVC/nanoclay composites were prepared by melt blending the aminosilane-treated wood flour, a heavy metal free PVC compound, and a type of nanoclay. The effects of treating wood flour with the aminosilanes and adding the nanoclay on the mechanical properties of the composites were investigated. Mechanical properties of the composites were investigated by universal testing machine (UTM), izod impact tester, dynamic mechanical analyzer (DMA), and thermomechanical analyzer (TMA). The tensile properties of the composites with the aminosilane-treated wood flour were considerably higher than those of the composites with neat wood flour. Furthermore, a small amount of the nanoclay improved mechanical properties of the composites. The performance of the wood/PVC composites was considerably improved by using the aminosilane-treated wood flour and the nanoclay.

• Polymer(Korea)
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• v.35 no.2
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• pp.124-129
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• 2011

Wood plastic composites (WPCs) are attracting a lot of interest recently. In this study, wood flour/polyethylene (PE) composites panels comprised of a coupling agent and nanoclay were prepared by melt-blending followed by compression molding. Five maleic anhydride grafted polyethylene (MAPE) coupling agents were tested, and the best choice and its optimum content were determined. The mechanical properties of the WPCs were measured by UTM, and the thermal properties were measured by TGA, DMA, DSC, and TMA. Adding just a small amount (1 phr) of organoclay made the tensile and flexural strength and the crystallinity of the WPC somewhat increase and the storage modulus and dimensional stability of the WPC largely increase. SEM images showed that the coupling agent drastically improved wood flour/PE interfacial bonding. Selecting the best coupling agent optimized content and adding a small amount of organoclay resulted in a high performance wood flour/PE composite.

• Elastomers and Composites
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• v.45 no.2
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• pp.129-136
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• 2010

In this work, PLLA/EGMA blends were prepared by melt blending of biodegradable Poly-L-lactic acid(PLLA) with Poly(ethylene-co-glycidyl methacrylate)(EGMA) and Engage as impact modifiers by twin screw extruder. Blend compositions of PLLA/Impact modifier blends were 100/0, 75/25, 50/50, 25/75 and 0/100, respectively. Also, Talc was added to 3 PLLA rich phases on PLLA/EGMA blends. The morphology, viscoelastic/mechanical properties were characterized by FESEM, DMA, UTM and Izod impact tester. DMA and Izod impact test data showed that storage modulus at room temperature with increasing EGMA and Engage contents decreased, and impact strength increased. However, storage modulus at room temperature increased by adding talc. From FESEM image, we observed that domain phase was well dispersed into matrix. Although the tensile strength and flexural modulus were decreased with increasing the content of EGMA and Engage in them, they could be supplemented by adding talc.