The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
A S Luyt - One of the best experts on this subject based on the ideXlab platform.
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thermal and mechanical properties of pp hdpe wood powder and mapp hdpe wood powder polymer blend composites
Thermochimica Acta, 2017Co-Authors: D G Dikobe, A S LuytAbstract:The morphology and properties of blends of PP/HDPE and MAPP/HDPE blends, and their composites with wood powder, were investigated in this paper. The blends showed two-phase morphologies, and MAPP interacted better than PP with HDPE, while the WP interacted more strongly with MAPP. Although the different components in the blends were immiscible, they showed one crystallization peak. MAPP and HDPE showed separate crystallization peaks in the composites, and this separation of the crystallization became more resolved with increasing WP content and at lower cooling rates. This was also observed for PP and HDPE in their composites, but to a lesser extent. Young’s modulus increased and the stress at break decreased with increasing WP content, and these were more pronounced in the PP/HDPE/WP composites. Interaction between WP and MAPP also had an influence on elongation at break. The presence of WP increased the thermal stability of the MAPP/HDPE and PP/HDPE.
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comparative study of the morphology and properties of pp lldpe wood powder and mapp lldpe wood powder polymer blend composites
Express Polymer Letters, 2010Co-Authors: D G Dikobe, A S LuytAbstract:In this study, polypropylene (PP)/linear low-density polyethylene (LLDPE) and maleic anhydride grafted polypropylene (MAPP)/LLDPE blend systems were comparatively investigated. The blends and composites contained equal amounts of the two polymers, and the compatibility and miscibility between the two polymers were investigated. Composites with 10, 20 and 30 wt% wood powder (WP), but still with equal amounts of the two polymers, were prepared and investigated. The morphologies, as well as mechanical and thermal properties, of the blends and the blend composites were investigated. The MAPP/LLDPE blend and composites showed better properties than the PP/LLDPE blend and com- posites as a result of the stronger interfacial interaction between MAPP, LLDPE and WP. The SEM and DSC results of the PP/LLDPE/WP blend composites showed that WP located itself more in the LLDPE phase. In the MAPP/LLDPE/WP composites the WP was in contact with both polymers, although it had a greater affinity for MAPP. The TGA results show that the MAPP/LLDPE blend and composites are more thermally stable than the PP/LLDPE blend and composites.
D G Dikobe - One of the best experts on this subject based on the ideXlab platform.
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thermal and mechanical properties of pp hdpe wood powder and mapp hdpe wood powder polymer blend composites
Thermochimica Acta, 2017Co-Authors: D G Dikobe, A S LuytAbstract:The morphology and properties of blends of PP/HDPE and MAPP/HDPE blends, and their composites with wood powder, were investigated in this paper. The blends showed two-phase morphologies, and MAPP interacted better than PP with HDPE, while the WP interacted more strongly with MAPP. Although the different components in the blends were immiscible, they showed one crystallization peak. MAPP and HDPE showed separate crystallization peaks in the composites, and this separation of the crystallization became more resolved with increasing WP content and at lower cooling rates. This was also observed for PP and HDPE in their composites, but to a lesser extent. Young’s modulus increased and the stress at break decreased with increasing WP content, and these were more pronounced in the PP/HDPE/WP composites. Interaction between WP and MAPP also had an influence on elongation at break. The presence of WP increased the thermal stability of the MAPP/HDPE and PP/HDPE.
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comparative study of the morphology and properties of pp lldpe wood powder and mapp lldpe wood powder polymer blend composites
Express Polymer Letters, 2010Co-Authors: D G Dikobe, A S LuytAbstract:In this study, polypropylene (PP)/linear low-density polyethylene (LLDPE) and maleic anhydride grafted polypropylene (MAPP)/LLDPE blend systems were comparatively investigated. The blends and composites contained equal amounts of the two polymers, and the compatibility and miscibility between the two polymers were investigated. Composites with 10, 20 and 30 wt% wood powder (WP), but still with equal amounts of the two polymers, were prepared and investigated. The morphologies, as well as mechanical and thermal properties, of the blends and the blend composites were investigated. The MAPP/LLDPE blend and composites showed better properties than the PP/LLDPE blend and com- posites as a result of the stronger interfacial interaction between MAPP, LLDPE and WP. The SEM and DSC results of the PP/LLDPE/WP blend composites showed that WP located itself more in the LLDPE phase. In the MAPP/LLDPE/WP composites the WP was in contact with both polymers, although it had a greater affinity for MAPP. The TGA results show that the MAPP/LLDPE blend and composites are more thermally stable than the PP/LLDPE blend and composites.
A Elsabbagh - One of the best experts on this subject based on the ideXlab platform.
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effect of coupling agent on natural fibre in natural fibre polypropylene composites on mechanical and thermal behaviour
Composites Part B-engineering, 2014Co-Authors: A ElsabbaghAbstract:Abstract To enhance the adhesion between the natural fibre and the thermoplastic matrix, a coupling agent of maleic anhydride grafted polypropylene MAPP is applied. In literature, there are different guidelines of the optimum percentage required of MAPP. Therefore, a systematic work is carried out to optimise the MAPP percent with respect to the type of the natural fibre. Different parameters are investigated namely; Coupling agent ratio to the fibre (0%, 6.67%, 10%, 13.3%, 16.67%), coupling agent source, fibre type (flax, hemp, sisal), and fibre content (30%, 50%). Composite is produced using a kneader and the resulting material is assessed mechanically, thermally, microscopically and for water absorption. For different MAPP source and the natural fibre type, optimum MAPP to fibre ratio is found in average to range between 10% and 13.3% according to the investigated property (stiffness, strength and impact). Increase of MAPP is found to decrease the melting temperature. The thermal behaviour is also linked to the copolymer molecular weight.
Hyunjoong Kim - One of the best experts on this subject based on the ideXlab platform.
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the effect of types of maleic anhydride grafted polypropylene mapp on the interfacial adhesion properties of bio flour filled polypropylene composites
Composites Part A-applied Science and Manufacturing, 2007Co-Authors: Heesoo Kim, Youngho Lee, Seungwoo Choi, Sumi Kim, Hyunjoong KimAbstract:The effect of processing temperature on the interfacial adhesion, mechanical properties and thermal stability of bio-flour-filled, polypropylene (PP) composites was examined as a function of five different maleic anhydride-grafted PP (MAPP) types. To investigate the effect on the interfacial adhesion of the composites, the five MAPP types were subjected to characterization tests. The MAPP-treated composites with sufficient molecular weight and maleic anhydride (MA) graft (%) showed improved mechanical and thermal stability. The enhanced interfacial adhesion, and mechanical and thermal stability of the MAPP-treated composites was strongly dependent on the amount of MA graft (%) and the MAPP molecular weight. The morphological properties of the MAPP-treated composites showed strong bonding and a paucity of pulled-out traces from the matrix in the two phases. In addition, the improved interfacial adhesion of the MAPP-treated composites was confirmed by spectral analysis of the chemical structure using attenuated total reflectance (FTIR-ATR). The crystallinity of PP, MAPP, MAPP-treated composites and non-treated composites was investigated using wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC).
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thermal properties of bio flour filled polyolefin composites with different compatibilizing agent type and content
Thermochimica Acta, 2006Co-Authors: Heesoo Kim, Hyunjoong Kim, Sumin Kim, Hanseung YangAbstract:Abstract The main objective of this research was to investigate the effect on thermal properties of the addition of two different compatibilizing agents, maleic anhydride (MA)-grafted polypropylene (MAPP) and MA-grafted polyethylene (MAPE), to bio-flour-filled, Polypropylene (PP) and low-density polyethylene (LDPE) composites. The effect of two different types of MAPE polymer, MA-grafted high-density polyethylene (HDPE-MA) and MA-grafted linear LDPE (LLDPE-MA), was also examined. With increasing MAPP and MAPE content, the thermal stability, storage modulus (E′), tan δmax peak temperature (glass transition temperature: Tg) and loss modulus ( E ″ max ) peak temperature (β relaxation) were slightly increased. The thermal stability, E′ and E″ of MAPE-treated composites were not significantly affected by the two different MAPE polymers. The melting temperature (Tm) of the composites was not significantly changed but the crystallinity (Xc) of MAPP- and MAPE-treated composites was slightly increased with increasing MAPP and MAPE content. This enhancement of thermal stability and properties could be attributed to an improvement in the interfacial adhesion and compatibility between the rice husk flour (RHF) and matrix due to the treatment of compatibilizing agent. Attenuated total reflectance (FTIR-ATR) analysis confirmed this result by demonstrating the changed chemical structures of the composites following MAPP and MAPE addition.
Socrates E. Papapoulos - One of the best experts on this subject based on the ideXlab platform.
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farnesyl pyrophosphate synthase is the molecular target of nitrogen containing bisphosphonates
Biochemical and Biophysical Research Communications, 1999Co-Authors: E Van Beek, Louis H Cohen, Elsbet J Pieterman, Clemens W.g.m. Löwik, Socrates E. PapapoulosAbstract:Bisphosphonates (Bps), inhibitors of osteoclastic bone resorption, are used in the treatment of skeletal disorders. Recent evidence indicated that farnesyl pyrophosphate (FPP) synthase and/or isopentenyl pyrophosphate (IPP) isomerase is the intracellular target(s) of bisphosphonate action. To examine which enzyme is specifically affected, we determined the effect of different Bps on incorporation of [14C]mevalonate (MVA), [14C]IPP, and [14C]dimethylallyl pyrophosphate (DMAPP) into polyisoprenyl pyrophosphates in a homogenate of bovine brain. HPLC analysis revealed that the three intermediates were incorporated into FPP and geranylgeranyl pyrophosphate (GGPP). In contrast to clodronate, the nitrogen-containing Bps (NBps), alendronate, risedronate, olpadronate, and ibandronate, completely blocked FPP and GGPP formation and induced in incubations with [14C]MVA a 3- to 5-fold increase in incorporation of label into IPP and/or DMAPP. Using a method that could distinguish DMAPP from IPP on basis of their difference in stability in acid, we found that none of the NBps affected the conversion of [14C]IPP into DMAPP, catalyzed by IPP isomerase, excluding this enzyme as target of NBp action. On the basis of these and our previous findings, we conclude that none of the enzymes up- or downstream of FPP synthase are affected by NBps, and FPP synthase is, therefore, the exclusive molecular target of NBp action. Chemicals/CAS: Carbon Radioisotopes; Carbon-Carbon Double Bond Isomerases, EC 5.3.3.-; Dimethylallyltranstransferase, EC 2.5.1.1; Diphosphonates; Enzyme Inhibitors; indolepropanol phosphate, 40716-80-1; Indoles; isopentenyldiphosphate delta-isomerase, EC 5.3.3.2; Mevalonic Acid, 150-97-0
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farnesyl pyrophosphate synthase is the molecular target of nitrogen containing bisphosphonates
Biochemical and Biophysical Research Communications, 1999Co-Authors: E Van Beek, Louis H Cohen, Elsbet J Pieterman, Clemens W.g.m. Löwik, Socrates E. PapapoulosAbstract:Bisphosphonates (Bps), inhibitors of osteoclastic bone resorption, are used in the treatment of skeletal disorders. Recent evidence indicated that farnesyl pyrophosphate (FPP) synthase and/or isopentenyl pyrophosphate (IPP) isomerase is the intracellular target(s) of bisphosphonate action. To examine which enzyme is specifically affected, we determined the effect of different Bps on incorporation of [(14)C]mevalonate (MVA), [(14)C]IPP, and [(14)C]dimethylallyl pyrophosphate (DMAPP) into polyisoprenyl pyrophosphates in a homogenate of bovine brain. HPLC analysis revealed that the three intermediates were incorporated into FPP and geranylgeranyl pyrophosphate (GGPP). In contrast to clodronate, the nitrogen-containing Bps (NBps), alendronate, risedronate, olpadronate, and ibandronate, completely blocked FPP and GGPP formation and induced in incubations with [(14)C]MVA a 3- to 5-fold increase in incorporation of label into IPP and/or DMAPP. Using a method that could distinguish DMAPP from IPP on basis of their difference in stability in acid, we found that none of the NBps affected the conversion of [(14)C]IPP into DMAPP, catalyzed by IPP isomerase, excluding this enzyme as target of NBp action. On the basis of these and our previous findings, we conclude that none of the enzymes up- or downstream of FPP synthase are affected by NBps, and FPP synthase is, therefore, the exclusive molecular target of NBp action.
