umesh makwana - Academia.edu (original) (raw)

Papers by umesh makwana

Three MgCl₂ supported TiCl₄ pro-catalysts; Cat-A, C... more Three MgCl₂ supported TiCl₄ pro-catalysts; Cat-A, Cat-B and Cat-C were synthesized. Cat-A was synthesized without any internal Lewis base (ILB); while Cat-B and Cat-C were synthesized using diisobutyl phthalate and ethyl benzoate as ILBs respectively. The effect of ILBs on stereoregularity and the microstructure of polybutadiene (PBD) was investigated. The vast differences in the amount of <i>trans-</i>1,4-structure of PBD by Cat-A, Cat-B and Cat-C systems were correlated with the nature of ILBs used by studying their polymerization kinetics. The energy barriers for polymerization reactions were calculated for all three catalysts systems using Arrhenius equation. Cat-B, has shown the highest energy barrier (23 kJ/mol) due to DIBP as ILB in its structure. Cat-A has given the lowest <i>trans</i>-1,4-PBD as it does not contain any ILB and has the minimum energy barrier (12 kJ/mol) while Cat-C has shown medium energy ...

This paper presents mathematical modelling and FEM analysis of PMBLDC motor. The machine paramete... more This paper presents mathematical modelling and FEM analysis of PMBLDC motor. The machine parameter of stator and rotor parts including torque speed characteristics and magnetic analysis are investigate by FEM analysis and analytically. The mathematical modelling of PMBLDC is carried out by the MATLAB software and FEM analysis is carried out by the ANSOFT MAXWELL software. Parameter of machine is calculated with high accuracy and precision. Perfect analysis can be achieved by comparing the results from above both processes of motor design. The analysis demonstrates the effectiveness of the proposed machines design methodology. PMBLDC motor with 550 Watt rating and 1500 rpm rated speed has been designed and the result of efficiency torque and cogging torque has been generated

Journal of emerging technologies and innovative research, 2019

L'invention concerne un procede de synthese d'alcoxyde de magnesium sous forme spheroide ... more L'invention concerne un procede de synthese d'alcoxyde de magnesium sous forme spheroide dote d'une resistance mecanique amelioree et d'une distribution etroite de tailles de particules, le procede comprenant la reaction de magnesium metallique, en presence d'iode, avec un melange d'alcools en chauffant par etapes, en premier lieu dans la plage de 40 °C a 65 °C pendant une duree de 2 heures, puis dans la plage de 65 °C a 80 °C pendant une duree de 1 heure, puis en maintenant la temperature de reaction a 80 °C pendant une duree de 6 a 10 heures. Les vapeurs du melange produites pendant la reaction sont condensees dans un condenseur de tete, l'hydrogene gazeux produit pendant la reaction est evacue et le melange d'alcools qui reste apres la reaction est filtre et reutilise. L'invention concerne egalement des particules spheroides d'alcoxyde de magnesium synthetisees par le procede, le procatalyseur Ziegler-Natta synthetise en utilisant l'alc...

We report the synthesis of hydroxyapatite nanoparticles by using calcium nitrate and orthophospho... more We report the synthesis of hydroxyapatite nanoparticles by using calcium nitrate and orthophosphoric acid. Pluronics (F127) was used as a templating agent. The HA prepared was characterized using TEM, SEM, X-ray diffraction and surface area. Mainly, the concentration of surfactants and reaction temperature was varied for morphological development of nanoparticles. By template assisted method, it was possible to synthesize HA nanorods with very high aspect ratio and mesoporosity. At higher concentrations and higher temperatures Nanorods were formed and lower concentrations and lower temperatures, nanospheres were formed. X-ray diffraction showed that the crystallite size increased with decrease in surfactant concentration. Additionally, apatite layer was formed of surface of HA when immersed in simulated body fluid. Layer of apatite in the form of nano roots sprouted from the HA surface after one day immersion time. Nanofibers were fabricated using synthesized nanoparticles and with PHB as polymer matrix by using electrospinning technique.

Journal of Macromolecular Science, Part A

Three MgCl2 supported TiCl4 pro-catalysts; Cat-A, Cat-B and Cat-C were synthesized. Cat-A was syn... more Three MgCl2 supported TiCl4 pro-catalysts; Cat-A, Cat-B and Cat-C were synthesized. Cat-A was synthesized without any internal Lewis base (ILB); while Cat-B and Cat-C were synthesized using diisobu...

Macromolecular Chemistry and Physics

An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal do... more An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal donors, differing in coordination nature on the structural aspects of MgCl2 matrix in high-performance MgCl2- supported titanium catalysts was developed using FTIR spectroscopy and WAXD studies. The analysis of the >C=0 stretching IR band of internal donors showed their coordination to (104) and (110) lateral cuts of MgCl2 matrix. Transformation of magnesium ethoxide {Mg(OEt)2} to MgCl2 during catalyst preparation resulted in different MgCl2 phases, namely the α-form, β-form, and the disordered δ5-form, which were analyzed by WAXD studies. The results from WAXD showed the relative preference of α-form over β-form in case of DIBP-based catalysts, which might be due to interlayer bridging between adjacent layers due to the bidendate nature of DIBP. This can be one of the reasons for the high productivity of dialkylphthalate-based catalysts in comparison to ethyl-benzoate-based catalyst sy...

Http Dx Doi Org 10 1080 15685551 2014 907611, Apr 16, 2014

ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst syst... more ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst system in presence of phenols. The effect of phenolic compounds such as 2,2′-methylenebis(4-tert-butyl-6-methylphenol) (PH1) and 4,4′-methylenebis(2,6- di-tert-butylphenol) (PH2) is studied on the productivity and stereospecificity of catalyst system as well as on molecular weight characteristics. The extent of stabilization of PP resin by phenolic compounds for oxidative degradation is determined by measurement of oxygen induction time. Molecular weight and b color change are also investigated before and after thermal aging. The catalyst productivity was found to be unaffected by the concentration of phenolic compounds in the studied range. The thermal stability of the polymer resin is, however, found to be dependent on the nature of phenolic compound. The masked PH1 phenolic compound showed better antioxidant characteristic as compared to PH2.

Catalysis Lett, 2009

TiCl 4 immobilization on different compositions of mixed support of MgCl 2 Á xEB and poly(methyl ... more TiCl 4 immobilization on different compositions of mixed support of MgCl 2 Á xEB and poly(methyl acrylate-co-1-octene) (PMO; synthesized through ARGET ATRP) resulted in the formation of solid catalysts having variation in incorporation of titanium. The effect of mixed support composition onto the titanium immobilization, catalyst morphology and performance for ethylene polymerizations has been evaluated. The polyethylenes synthesized showed broad to bimodal MWD in GPC and DSC where the broadness was found to be dependent upon the ratio of mixed support MgCl 2 Á xEB/PMO. The morphological features of PE as elucidated using SEM lead to postulation of polymer formation mechanism.

Catalysis Lett, 2009

High performance MgCl 2 supported titanium catalyst having diisobutyl phthalate (DIBP) as interna... more High performance MgCl 2 supported titanium catalyst having diisobutyl phthalate (DIBP) as internal donor has been synthesized. The organic components present in the catalyst have been studied through FTIR, 1D and 2D NMR spectroscopy. The results indicate presence of diethyl phthalate also in addition to DIBP. WAXD analysis has been done to study the features of MgCl 2 crystallites. Impact of donor components on the catalyst preparation leading to reaction pathways and performance for propylene polymerization has been evaluated.

invention relates to a process for the synthesis of spheroidal magnesium alkoxide having improved... more invention relates to a process for the synthesis of spheroidal magnesium alkoxide having improved mechanical strength and narrow particle size distribution, the process comprising reacting magnesium metal, in the presence of iodine, with a mixture of alcohols by step-wise heating first in the range of 40° C. to 65° C. for a period of 2 hours and then in the range of 65° C. to 80° C. for a period of 1 hour, further by maintaining reaction temperature at 80° C. for a period of 6-10 hours, the vapors of the mixture produced during the reaction being condensed in an overhead condenser, hydrogen gas produced during the reaction being vented off and the mixture of alcohols left after the reaction being filtered and reused. The invention also relates to spheroidal magnesium alkoxide particles synthesized by the method, to the Ziegler natta procatalyst synthesized by using the alkoxide and to the polymer resin synthesized using the procatalyst.

e-Polymers, 2012

Long chain aliphatic ester, isopropyl myristate, was synthesized using energy efficient microwave... more Long chain aliphatic ester, isopropyl myristate, was synthesized using energy efficient microwave irradiation technique. The iso propyl myristate forms complexes with titanium tetrachloride in different mole ratios. The nature of chemical bonding between the titanium and the ester functionality was investigated by FTIR and NMR spectroscopy. The performance of synthesized complexes with methylalumoxane as co-catalyst for ethylene polymerization was found to depend on the nature of complex and polymerization parameters. Molecular weight and thermal characteristics of polyethylene was also investigated.

Designed Monomers and Polymers, 2013

ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst syst... more ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst system in presence of phenols. The effect of phenolic compounds such as 2,2′-methylenebis(4-tert-butyl-6-methylphenol) (PH1) and 4,4′-methylenebis(2,6- di-tert-butylphenol) (PH2) is studied on the productivity and stereospecificity of catalyst system as well as on molecular weight characteristics. The extent of stabilization of PP resin by phenolic compounds for oxidative degradation is determined by measurement of oxygen induction time. Molecular weight and b color change are also investigated before and after thermal aging. The catalyst productivity was found to be unaffected by the concentration of phenolic compounds in the studied range. The thermal stability of the polymer resin is, however, found to be dependent on the nature of phenolic compound. The masked PH1 phenolic compound showed better antioxidant characteristic as compared to PH2.

Macromolecular Chemistry and Physics, 2009

An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal do... more An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal donors, differing in coordination nature on the structural aspects of MgCl 2 matrix in high-performance MgCl 2 -supported titanium catalysts was developed using FTIR spectroscopy and WAXD ...

Liquid Crystals, 2013

ABSTRACT Novel liquid crystals, including 2-[4-(4 ′ -n-alkoxybenzoyloxy)phenylazo]-6-fluorobenzot... more ABSTRACT Novel liquid crystals, including 2-[4-(4 ′ -n-alkoxybenzoyloxy)phenylazo]-6-fluorobenzothiazoles (Series E) and 2-[4-(4 ′ -n-alkoxybenzoyloxy)naphtha-1-ylazo]-6-fluorobenzothiazoles (Series F), have been synthesised and characterised. Each series contains 13 homologous members differing by the length of the alkoxy chain. In series E the derivative with C1 to C7 chain length were found to exhibit enantiotropic smectic C (SmC) and nematic (N) mesophases. The C8 homologue possessed enantiotropic SmC, smectic A (SmA) and N mesophases, while the longer chain homologues (C10 to C14) showed enantiotropic SmC and SmA mesophases. The C16 and C18 homologues possessed only SmA mesophases. In Series F all the compounds (C1 to C18) exhibited only the enantiotropic nematic mesophase.

Journal of Molecular Liquids, 2010

Journal of Applied Polymer Science, 2012

Magnesium dichloride supported titanium catalyst incorporated with varying concentration of ethyl... more Magnesium dichloride supported titanium catalyst incorporated with varying concentration of ethylbenzoate and diisobutyl phthalate together as internal donor are synthesized. The synthesized catalysts are characterized and compared with respect to composition, phase characteristics, crystallite size, and particle morphology. Performance of catalysts containing mixed donors is compared with the conventional single donor-based catalysts. The polymerization studies of the catalysts for propylene polymerization show dependence of polymerization kinetics on relative concentration of diisobutyl phthalate and ethylbenzoate. Molecular weight characteristics of polypropylene obtained from these catalysts are studied and correlated with the nature and concentration of donors present in the catalyst. Morphology replication from catalyst precursor to polymer is observed irrespective of the nature of donor being incorporated in the synthesized catalyst.

Three MgCl₂ supported TiCl₄ pro-catalysts; Cat-A, C... more Three MgCl₂ supported TiCl₄ pro-catalysts; Cat-A, Cat-B and Cat-C were synthesized. Cat-A was synthesized without any internal Lewis base (ILB); while Cat-B and Cat-C were synthesized using diisobutyl phthalate and ethyl benzoate as ILBs respectively. The effect of ILBs on stereoregularity and the microstructure of polybutadiene (PBD) was investigated. The vast differences in the amount of <i>trans-</i>1,4-structure of PBD by Cat-A, Cat-B and Cat-C systems were correlated with the nature of ILBs used by studying their polymerization kinetics. The energy barriers for polymerization reactions were calculated for all three catalysts systems using Arrhenius equation. Cat-B, has shown the highest energy barrier (23 kJ/mol) due to DIBP as ILB in its structure. Cat-A has given the lowest <i>trans</i>-1,4-PBD as it does not contain any ILB and has the minimum energy barrier (12 kJ/mol) while Cat-C has shown medium energy ...

This paper presents mathematical modelling and FEM analysis of PMBLDC motor. The machine paramete... more This paper presents mathematical modelling and FEM analysis of PMBLDC motor. The machine parameter of stator and rotor parts including torque speed characteristics and magnetic analysis are investigate by FEM analysis and analytically. The mathematical modelling of PMBLDC is carried out by the MATLAB software and FEM analysis is carried out by the ANSOFT MAXWELL software. Parameter of machine is calculated with high accuracy and precision. Perfect analysis can be achieved by comparing the results from above both processes of motor design. The analysis demonstrates the effectiveness of the proposed machines design methodology. PMBLDC motor with 550 Watt rating and 1500 rpm rated speed has been designed and the result of efficiency torque and cogging torque has been generated

Journal of emerging technologies and innovative research, 2019

L'invention concerne un procede de synthese d'alcoxyde de magnesium sous forme spheroide ... more L'invention concerne un procede de synthese d'alcoxyde de magnesium sous forme spheroide dote d'une resistance mecanique amelioree et d'une distribution etroite de tailles de particules, le procede comprenant la reaction de magnesium metallique, en presence d'iode, avec un melange d'alcools en chauffant par etapes, en premier lieu dans la plage de 40 °C a 65 °C pendant une duree de 2 heures, puis dans la plage de 65 °C a 80 °C pendant une duree de 1 heure, puis en maintenant la temperature de reaction a 80 °C pendant une duree de 6 a 10 heures. Les vapeurs du melange produites pendant la reaction sont condensees dans un condenseur de tete, l'hydrogene gazeux produit pendant la reaction est evacue et le melange d'alcools qui reste apres la reaction est filtre et reutilise. L'invention concerne egalement des particules spheroides d'alcoxyde de magnesium synthetisees par le procede, le procatalyseur Ziegler-Natta synthetise en utilisant l'alc...

We report the synthesis of hydroxyapatite nanoparticles by using calcium nitrate and orthophospho... more We report the synthesis of hydroxyapatite nanoparticles by using calcium nitrate and orthophosphoric acid. Pluronics (F127) was used as a templating agent. The HA prepared was characterized using TEM, SEM, X-ray diffraction and surface area. Mainly, the concentration of surfactants and reaction temperature was varied for morphological development of nanoparticles. By template assisted method, it was possible to synthesize HA nanorods with very high aspect ratio and mesoporosity. At higher concentrations and higher temperatures Nanorods were formed and lower concentrations and lower temperatures, nanospheres were formed. X-ray diffraction showed that the crystallite size increased with decrease in surfactant concentration. Additionally, apatite layer was formed of surface of HA when immersed in simulated body fluid. Layer of apatite in the form of nano roots sprouted from the HA surface after one day immersion time. Nanofibers were fabricated using synthesized nanoparticles and with PHB as polymer matrix by using electrospinning technique.

Journal of Macromolecular Science, Part A

Three MgCl2 supported TiCl4 pro-catalysts; Cat-A, Cat-B and Cat-C were synthesized. Cat-A was syn... more Three MgCl2 supported TiCl4 pro-catalysts; Cat-A, Cat-B and Cat-C were synthesized. Cat-A was synthesized without any internal Lewis base (ILB); while Cat-B and Cat-C were synthesized using diisobu...

Macromolecular Chemistry and Physics

An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal do... more An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal donors, differing in coordination nature on the structural aspects of MgCl2 matrix in high-performance MgCl2- supported titanium catalysts was developed using FTIR spectroscopy and WAXD studies. The analysis of the >C=0 stretching IR band of internal donors showed their coordination to (104) and (110) lateral cuts of MgCl2 matrix. Transformation of magnesium ethoxide {Mg(OEt)2} to MgCl2 during catalyst preparation resulted in different MgCl2 phases, namely the α-form, β-form, and the disordered δ5-form, which were analyzed by WAXD studies. The results from WAXD showed the relative preference of α-form over β-form in case of DIBP-based catalysts, which might be due to interlayer bridging between adjacent layers due to the bidendate nature of DIBP. This can be one of the reasons for the high productivity of dialkylphthalate-based catalysts in comparison to ethyl-benzoate-based catalyst sy...

Http Dx Doi Org 10 1080 15685551 2014 907611, Apr 16, 2014

ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst syst... more ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst system in presence of phenols. The effect of phenolic compounds such as 2,2′-methylenebis(4-tert-butyl-6-methylphenol) (PH1) and 4,4′-methylenebis(2,6- di-tert-butylphenol) (PH2) is studied on the productivity and stereospecificity of catalyst system as well as on molecular weight characteristics. The extent of stabilization of PP resin by phenolic compounds for oxidative degradation is determined by measurement of oxygen induction time. Molecular weight and b color change are also investigated before and after thermal aging. The catalyst productivity was found to be unaffected by the concentration of phenolic compounds in the studied range. The thermal stability of the polymer resin is, however, found to be dependent on the nature of phenolic compound. The masked PH1 phenolic compound showed better antioxidant characteristic as compared to PH2.

Catalysis Lett, 2009

TiCl 4 immobilization on different compositions of mixed support of MgCl 2 Á xEB and poly(methyl ... more TiCl 4 immobilization on different compositions of mixed support of MgCl 2 Á xEB and poly(methyl acrylate-co-1-octene) (PMO; synthesized through ARGET ATRP) resulted in the formation of solid catalysts having variation in incorporation of titanium. The effect of mixed support composition onto the titanium immobilization, catalyst morphology and performance for ethylene polymerizations has been evaluated. The polyethylenes synthesized showed broad to bimodal MWD in GPC and DSC where the broadness was found to be dependent upon the ratio of mixed support MgCl 2 Á xEB/PMO. The morphological features of PE as elucidated using SEM lead to postulation of polymer formation mechanism.

Catalysis Lett, 2009

High performance MgCl 2 supported titanium catalyst having diisobutyl phthalate (DIBP) as interna... more High performance MgCl 2 supported titanium catalyst having diisobutyl phthalate (DIBP) as internal donor has been synthesized. The organic components present in the catalyst have been studied through FTIR, 1D and 2D NMR spectroscopy. The results indicate presence of diethyl phthalate also in addition to DIBP. WAXD analysis has been done to study the features of MgCl 2 crystallites. Impact of donor components on the catalyst preparation leading to reaction pathways and performance for propylene polymerization has been evaluated.

invention relates to a process for the synthesis of spheroidal magnesium alkoxide having improved... more invention relates to a process for the synthesis of spheroidal magnesium alkoxide having improved mechanical strength and narrow particle size distribution, the process comprising reacting magnesium metal, in the presence of iodine, with a mixture of alcohols by step-wise heating first in the range of 40° C. to 65° C. for a period of 2 hours and then in the range of 65° C. to 80° C. for a period of 1 hour, further by maintaining reaction temperature at 80° C. for a period of 6-10 hours, the vapors of the mixture produced during the reaction being condensed in an overhead condenser, hydrogen gas produced during the reaction being vented off and the mixture of alcohols left after the reaction being filtered and reused. The invention also relates to spheroidal magnesium alkoxide particles synthesized by the method, to the Ziegler natta procatalyst synthesized by using the alkoxide and to the polymer resin synthesized using the procatalyst.

e-Polymers, 2012

Long chain aliphatic ester, isopropyl myristate, was synthesized using energy efficient microwave... more Long chain aliphatic ester, isopropyl myristate, was synthesized using energy efficient microwave irradiation technique. The iso propyl myristate forms complexes with titanium tetrachloride in different mole ratios. The nature of chemical bonding between the titanium and the ester functionality was investigated by FTIR and NMR spectroscopy. The performance of synthesized complexes with methylalumoxane as co-catalyst for ethylene polymerization was found to depend on the nature of complex and polymerization parameters. Molecular weight and thermal characteristics of polyethylene was also investigated.

Designed Monomers and Polymers, 2013

ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst syst... more ABSTRACT Stabilized polypropylene synthesis is carried out using supported titanium catalyst system in presence of phenols. The effect of phenolic compounds such as 2,2′-methylenebis(4-tert-butyl-6-methylphenol) (PH1) and 4,4′-methylenebis(2,6- di-tert-butylphenol) (PH2) is studied on the productivity and stereospecificity of catalyst system as well as on molecular weight characteristics. The extent of stabilization of PP resin by phenolic compounds for oxidative degradation is determined by measurement of oxygen induction time. Molecular weight and b color change are also investigated before and after thermal aging. The catalyst productivity was found to be unaffected by the concentration of phenolic compounds in the studied range. The thermal stability of the polymer resin is, however, found to be dependent on the nature of phenolic compound. The masked PH1 phenolic compound showed better antioxidant characteristic as compared to PH2.

Macromolecular Chemistry and Physics, 2009

An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal do... more An insight on the influence of ethyl benzoate (EB) and diisobutyl phthalate (DIBP) as internal donors, differing in coordination nature on the structural aspects of MgCl 2 matrix in high-performance MgCl 2 -supported titanium catalysts was developed using FTIR spectroscopy and WAXD ...

Liquid Crystals, 2013

ABSTRACT Novel liquid crystals, including 2-[4-(4 ′ -n-alkoxybenzoyloxy)phenylazo]-6-fluorobenzot... more ABSTRACT Novel liquid crystals, including 2-[4-(4 ′ -n-alkoxybenzoyloxy)phenylazo]-6-fluorobenzothiazoles (Series E) and 2-[4-(4 ′ -n-alkoxybenzoyloxy)naphtha-1-ylazo]-6-fluorobenzothiazoles (Series F), have been synthesised and characterised. Each series contains 13 homologous members differing by the length of the alkoxy chain. In series E the derivative with C1 to C7 chain length were found to exhibit enantiotropic smectic C (SmC) and nematic (N) mesophases. The C8 homologue possessed enantiotropic SmC, smectic A (SmA) and N mesophases, while the longer chain homologues (C10 to C14) showed enantiotropic SmC and SmA mesophases. The C16 and C18 homologues possessed only SmA mesophases. In Series F all the compounds (C1 to C18) exhibited only the enantiotropic nematic mesophase.

Journal of Molecular Liquids, 2010

Journal of Applied Polymer Science, 2012

Magnesium dichloride supported titanium catalyst incorporated with varying concentration of ethyl... more Magnesium dichloride supported titanium catalyst incorporated with varying concentration of ethylbenzoate and diisobutyl phthalate together as internal donor are synthesized. The synthesized catalysts are characterized and compared with respect to composition, phase characteristics, crystallite size, and particle morphology. Performance of catalysts containing mixed donors is compared with the conventional single donor-based catalysts. The polymerization studies of the catalysts for propylene polymerization show dependence of polymerization kinetics on relative concentration of diisobutyl phthalate and ethylbenzoate. Molecular weight characteristics of polypropylene obtained from these catalysts are studied and correlated with the nature and concentration of donors present in the catalyst. Morphology replication from catalyst precursor to polymer is observed irrespective of the nature of donor being incorporated in the synthesized catalyst.