Pub Date : 2017-10-04DOI: 10.6000/1929-5995.2017.06.03.2
M. Rajab, T. Hamieh, A. Airoudj, K. Mougin, Kamal Hariri, W. Rammal, Houssein Mortada, M. Akil, A. Kassas, J. Toufaily
A linear diblock copolymer [Polystyrene-b-Poly(4-vinyl-pyridine)] (PS-b-P4VP) was successfully prepared through Atom Transfer Radical Polymerization (ATRP). This synthesis is performed in two successive steps: using the (1-bromoethyl) benzene as initiatorand and Hexamethyl tris [2(dimethylamino)ethyl] amine as ligands in a protic solvent. The first step of the synthesis allows the realization of block polystyrene having a terminal function; however, Bromine (Br) permits the grafting of the second successive block P4VP. RMN -1H demonstrates that the P4VP block has been grafted onto the PS block. The molecular weight of PS-b-P4VP is determined by size exclusion chromatography, and its thermal stability is examined by TGA. The surface and the thermodynamic properties of this copolymer are studied by inverse gas chromatography (IGC). The new Hamieh Model shows that the synthesized copolymer PS-P4VP has an amphoteric behavior with rather very basic character that is six times stronger than acidic character (in Lewis terms), reflected the presence of acidic and basic groups in the structure of the PS-P4VP copolymer, more particularly the presence of benzenic, methyl and vinylpyridine groups.
{"title":"Synthesis by ATRP of Polystyrene-b-Poly(4-vinylpyridine) and Characterization by Inverse Gas Chromatography","authors":"M. Rajab, T. Hamieh, A. Airoudj, K. Mougin, Kamal Hariri, W. Rammal, Houssein Mortada, M. Akil, A. Kassas, J. Toufaily","doi":"10.6000/1929-5995.2017.06.03.2","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.03.2","url":null,"abstract":"A linear diblock copolymer [Polystyrene-b-Poly(4-vinyl-pyridine)] (PS-b-P4VP) was successfully prepared through Atom Transfer Radical Polymerization (ATRP). This synthesis is performed in two successive steps: using the (1-bromoethyl) benzene as initiatorand and Hexamethyl tris [2(dimethylamino)ethyl] amine as ligands in a protic solvent. The first step of the synthesis allows the realization of block polystyrene having a terminal function; however, Bromine (Br) permits the grafting of the second successive block P4VP. RMN -1H demonstrates that the P4VP block has been grafted onto the PS block. The molecular weight of PS-b-P4VP is determined by size exclusion chromatography, and its thermal stability is examined by TGA. The surface and the thermodynamic properties of this copolymer are studied by inverse gas chromatography (IGC). The new Hamieh Model shows that the synthesized copolymer PS-P4VP has an amphoteric behavior with rather very basic character that is six times stronger than acidic character (in Lewis terms), reflected the presence of acidic and basic groups in the structure of the PS-P4VP copolymer, more particularly the presence of benzenic, methyl and vinylpyridine groups.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"51 1","pages":"76-89"},"PeriodicalIF":0.0,"publicationDate":"2017-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89480386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-16DOI: 10.6000/1929-5995.2017.06.02.1
N. Nassif
Stretchable fabrics have gained much interest in the last few years because their higher comforts and aesthetic properties. The main parameters which control the stretchable fabric properties were found to be spandex linear density and draft ratio. In this research paper, the influences of these variables on color properties of stretchable fabrics were investigated. Color properties of the stretchable fabrics were characterized by whiteness index, K/S values, and colorfastness to washing, rubbing and perspiration. The results of this work showed that color properties of the stretchable woven fabrics were affected by independent variables. Generally, impact of spandex draft ratio on color properties was more pronounced than the effects of spandex linear density.
{"title":"Color and Fastness Properties of Woven Stretchable Fabrics","authors":"N. Nassif","doi":"10.6000/1929-5995.2017.06.02.1","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.02.1","url":null,"abstract":"Stretchable fabrics have gained much interest in the last few years because their higher comforts and aesthetic properties. The main parameters which control the stretchable fabric properties were found to be spandex linear density and draft ratio. In this research paper, the influences of these variables on color properties of stretchable fabrics were investigated. Color properties of the stretchable fabrics were characterized by whiteness index, K/S values, and colorfastness to washing, rubbing and perspiration. The results of this work showed that color properties of the stretchable woven fabrics were affected by independent variables. Generally, impact of spandex draft ratio on color properties was more pronounced than the effects of spandex linear density.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"18 1","pages":"33-38"},"PeriodicalIF":0.0,"publicationDate":"2017-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81699643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-16DOI: 10.6000/1929-5995.2017.06.02.2
V. Ryzhov
Polarization far-IR spectroscopy has been used to carry out a comparative study of the spectra of granules and fibers of completely aromatic thermotropic liquid-crystal copolymer Vectra A950. The analysis of terahertz polarization IR spectra Vectra A950 showed that in contrast to the mid-IR, dichroic ratio of the absorption bands in the spectra of fibers and granules, substantially different. It is shown that the difference between the value and the orientation order parameter in the samples is determined by and correlated with the intensity of the local dynamics of polymer chains, such as the librational mobility of phenylene and naphthalene rings of the copolymer mesogens. The results suggest the possibility carrying out an independent evaluation of the spectroscopic parameters reflecting the properties of intermolecular interactions in oriented the liquid-crystalline polymers for their low-frequency spectra.
{"title":"Peculiarities of The Orientational State of Liquid-Crystal Completely Aromatic Thermotropic Copolymer","authors":"V. Ryzhov","doi":"10.6000/1929-5995.2017.06.02.2","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.02.2","url":null,"abstract":"Polarization far-IR spectroscopy has been used to carry out a comparative study of the spectra of granules and fibers of completely aromatic thermotropic liquid-crystal copolymer Vectra A950. The analysis of terahertz polarization IR spectra Vectra A950 showed that in contrast to the mid-IR, dichroic ratio of the absorption bands in the spectra of fibers and granules, substantially different. It is shown that the difference between the value and the orientation order parameter in the samples is determined by and correlated with the intensity of the local dynamics of polymer chains, such as the librational mobility of phenylene and naphthalene rings of the copolymer mesogens. The results suggest the possibility carrying out an independent evaluation of the spectroscopic parameters reflecting the properties of intermolecular interactions in oriented the liquid-crystalline polymers for their low-frequency spectra.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"36 1","pages":"39-44"},"PeriodicalIF":0.0,"publicationDate":"2017-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88440553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-16DOI: 10.6000/1929-5995.2017.06.02.3
E. M. Abdelrazek, A. Abdelghany, S. I. Badr, M. Morsi
Gold nanoparticles (Au NPs) have been successfully biosynthesized by Chenopodium murale ( C. murale ) leaf extract. Au NPs were incorporated within polyethylene oxide (PEO)/polyvinyl pyrrolidone (PVP) polymer blend by casting method. Scanning electron microscope (SEM), Differential scanning calorimetry (DSC), and DC electrical resistivity were used to investigate the morphological, thermal, and electrical properties of blend/Au nanocomposite before and after gamma-irradiation at different doses (1, 2, 3, 4 and 5 MR).SEM micrographs confirmed the dispersion of Au NPs within the polymeric matrix due to effect of irradiation process. DSC analysis showed that the thermal stability for irradiated samples was improved as compared with pure blend and its nanocomposite. DC measurements revealed nonlinear behavior for electrical resistivity versus temperature. The electrical resistivity values for blend/Au nanocopmosite and its high irradiated samples were less compared to pure blend.
{"title":"Morphological, Thermal and Electrical Properties of (PEO/PVP)/ Au Nanocomposite Before and After Gamma-Irradiation","authors":"E. M. Abdelrazek, A. Abdelghany, S. I. Badr, M. Morsi","doi":"10.6000/1929-5995.2017.06.02.3","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.02.3","url":null,"abstract":"Gold nanoparticles (Au NPs) have been successfully biosynthesized by Chenopodium murale ( C. murale ) leaf extract. Au NPs were incorporated within polyethylene oxide (PEO)/polyvinyl pyrrolidone (PVP) polymer blend by casting method. Scanning electron microscope (SEM), Differential scanning calorimetry (DSC), and DC electrical resistivity were used to investigate the morphological, thermal, and electrical properties of blend/Au nanocomposite before and after gamma-irradiation at different doses (1, 2, 3, 4 and 5 MR).SEM micrographs confirmed the dispersion of Au NPs within the polymeric matrix due to effect of irradiation process. DSC analysis showed that the thermal stability for irradiated samples was improved as compared with pure blend and its nanocomposite. DC measurements revealed nonlinear behavior for electrical resistivity versus temperature. The electrical resistivity values for blend/Au nanocopmosite and its high irradiated samples were less compared to pure blend.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"44 1","pages":"45-54"},"PeriodicalIF":0.0,"publicationDate":"2017-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82260387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-16DOI: 10.6000/1929-5995.2017.06.02.4
F. Benmouna, M. Benmouna
Phase separated blends of polymers and low molecular weight liquid crystals, commonly known as polymer dispersed liquid crystals in short PDLCs, are investigated. These materials offer a realm of applications in modern technologies, including sensors, commutable windows, display devices and telecommunication systems. A particular attention is given to the effects of anisotropy of the liquid crystal on the phase behavior under equilibrium and non equilibrium conditions. The theoretical formalism used is based on the lattice model of isotropic mixing, combined with standards theories of nematic and smectic-A orders. Considering the equilibrium phase behavior, we find that the nematic order enhances the polymer / solvent phase separation, and that the osmotic pressure shows substantial changes for relatively small polymer volume fractions. We find that the anisotropy enhanced phase separation is more pronounced for a smectic-A liquid crystal, and the miscibility gap is widened. The kinetics of swelling by nematic LCs is examined using a linear solvent diffusion process, with a rate of swelling directly related to the derivative of the osmotic pressure. An abrupt swelling / de-swelling transition is found, due to overwhelming effects of the anisotropic interaction beyond the threshold LC concentration. Anisotropy enhanced phase separation is also investigated in the method of synthesis based on the polymerization induced phase separation mechanism. We find that the kinetics of separation during early stages of polymerization is faster, due to the anisotropic interaction of the low molecular weight solvent. The kinetics speed up is favored by the long range viscous flow effects due to hydrodynamic interactions. A limited selection of experimental data in the literature is chosen to validate some theoretical predictions obtained from the present formalisms.
{"title":"Anisotropy Enhanced Phase Separation in Polymer Dispersed Liquid Crystals","authors":"F. Benmouna, M. Benmouna","doi":"10.6000/1929-5995.2017.06.02.4","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.02.4","url":null,"abstract":"Phase separated blends of polymers and low molecular weight liquid crystals, commonly known as polymer dispersed liquid crystals in short PDLCs, are investigated. These materials offer a realm of applications in modern technologies, including sensors, commutable windows, display devices and telecommunication systems. A particular attention is given to the effects of anisotropy of the liquid crystal on the phase behavior under equilibrium and non equilibrium conditions. The theoretical formalism used is based on the lattice model of isotropic mixing, combined with standards theories of nematic and smectic-A orders. Considering the equilibrium phase behavior, we find that the nematic order enhances the polymer / solvent phase separation, and that the osmotic pressure shows substantial changes for relatively small polymer volume fractions. We find that the anisotropy enhanced phase separation is more pronounced for a smectic-A liquid crystal, and the miscibility gap is widened. The kinetics of swelling by nematic LCs is examined using a linear solvent diffusion process, with a rate of swelling directly related to the derivative of the osmotic pressure. An abrupt swelling / de-swelling transition is found, due to overwhelming effects of the anisotropic interaction beyond the threshold LC concentration. Anisotropy enhanced phase separation is also investigated in the method of synthesis based on the polymerization induced phase separation mechanism. We find that the kinetics of separation during early stages of polymerization is faster, due to the anisotropic interaction of the low molecular weight solvent. The kinetics speed up is favored by the long range viscous flow effects due to hydrodynamic interactions. A limited selection of experimental data in the literature is chosen to validate some theoretical predictions obtained from the present formalisms.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"37 1","pages":"55-67"},"PeriodicalIF":0.0,"publicationDate":"2017-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85874693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-04-06DOI: 10.6000/1929-5995.2017.06.01.1
K. Benini, H. Voorwald, M. Cioffi
Natural fibers obtained from sugarcane bagasse were used as reinforcement for high impact polystyrene (HIPS) composites. Fibers were chemically treated with an alkaline solution and then bleached with sodium chlorite and acetic acid, in order to remove amorphous constituents and improve adhesion with polimeric matrix.The alkali-treated and bleached fibers over a range of 10-30 wt% were mixed with HIPS and placed in an injector chamber in order to obtain tensile and flexural test specimens. Chemical treatment effects on composites properties were evaluated through mechanical tests and thermal and microscopy analysis. Experimental results show that composites with 30 wt% of alkali-treated fibers present an improvement in the tensile strength (17%), tensile modulus (96%) and flexural modulus (34%) with a consequent decrease in the ductility and in the thermal properties in comparisson to pure HIPS. An huge increase of 191% in the flexural modulus for composites with 30 wt% of bleached fibers was obtained compared to pure HIPS.
{"title":"Manufacturing and Characterization of High Impact Polystyrene (HIPS) Reinforced with Treated Sugarcane Bagasse","authors":"K. Benini, H. Voorwald, M. Cioffi","doi":"10.6000/1929-5995.2017.06.01.1","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.01.1","url":null,"abstract":"Natural fibers obtained from sugarcane bagasse were used as reinforcement for high impact polystyrene (HIPS) composites. Fibers were chemically treated with an alkaline solution and then bleached with sodium chlorite and acetic acid, in order to remove amorphous constituents and improve adhesion with polimeric matrix.The alkali-treated and bleached fibers over a range of 10-30 wt% were mixed with HIPS and placed in an injector chamber in order to obtain tensile and flexural test specimens. Chemical treatment effects on composites properties were evaluated through mechanical tests and thermal and microscopy analysis. Experimental results show that composites with 30 wt% of alkali-treated fibers present an improvement in the tensile strength (17%), tensile modulus (96%) and flexural modulus (34%) with a consequent decrease in the ductility and in the thermal properties in comparisson to pure HIPS. An huge increase of 191% in the flexural modulus for composites with 30 wt% of bleached fibers was obtained compared to pure HIPS.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"8 1","pages":"2-11"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77253976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-04-06DOI: 10.6000/1929-5995.2017.06.01.3
G. B. Pereira, Glayce Cassaro Pereira, Márcio Lima, B. J. S. Jesus, E. Silva, K. Benini, C. F. Bandeira, S. R. Montoro
Studies focused on generating products able to reduce environmental impact have been put in place, and those aiming at finding polymeric composites strengthened with natural fibers stand out among them. A composite was strengthened with coconut fibers in the present study, since the generation of coconut residues has increased in Brazil due to coconut water industrialization. The aim of the present study is to process a high impact polystyrene (HIPS) composite strengthened with coconut fiber and to verify its possible application in the automotive industry. Strengthened samples were prepared using coconut fibers in the proportions 10, 20 and 30% fiber to develop such HIPS composite. Analyses were performed in order to set the density, Shore A hardness and impact resistance of the processed composites. It was found that the density and Shore A hardness results in the HIPS did not change due to the addition of coconut fibers. However, it was observed that the impact resistance was reduced because of it. It was noteworthy that the decreased impact resistance did not preclude the use of the HIPS/coconut fiber composite, since it showed that such material can be used in parts free from strong mechanical stress such as those inside the automobiles. The use of coir HIPS also aimed at reducing costs related to the polymer’s consumption and at reusing the waste (coconut husk) from coconut water industries.
{"title":"Featuring High Impact Polystyrene Composites Strengthened with Green Coconut Fiber Developed for Automotive Industry Application","authors":"G. B. Pereira, Glayce Cassaro Pereira, Márcio Lima, B. J. S. Jesus, E. Silva, K. Benini, C. F. Bandeira, S. R. Montoro","doi":"10.6000/1929-5995.2017.06.01.3","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.01.3","url":null,"abstract":"Studies focused on generating products able to reduce environmental impact have been put in place, and those aiming at finding polymeric composites strengthened with natural fibers stand out among them. A composite was strengthened with coconut fibers in the present study, since the generation of coconut residues has increased in Brazil due to coconut water industrialization. The aim of the present study is to process a high impact polystyrene (HIPS) composite strengthened with coconut fiber and to verify its possible application in the automotive industry. Strengthened samples were prepared using coconut fibers in the proportions 10, 20 and 30% fiber to develop such HIPS composite. Analyses were performed in order to set the density, Shore A hardness and impact resistance of the processed composites. It was found that the density and Shore A hardness results in the HIPS did not change due to the addition of coconut fibers. However, it was observed that the impact resistance was reduced because of it. It was noteworthy that the decreased impact resistance did not preclude the use of the HIPS/coconut fiber composite, since it showed that such material can be used in parts free from strong mechanical stress such as those inside the automobiles. The use of coir HIPS also aimed at reducing costs related to the polymer’s consumption and at reusing the waste (coconut husk) from coconut water industries.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"14 1","pages":"17-20"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88088374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-04-06DOI: 10.6000/1929-5995.2017.06.01.4
Z. Salleh, Mainul Islam, J. Epaarachchi
This paper presented the stress concentration factor (SCF) around the half circular edge of tensile specimens made of syntactic foam using finite element software Strand7 software. The study is a preliminary effort, which investigates the effect of variations of crack geometry on the stress concentration factor on a tensile specimen subjected to a constant, uniform, uniaxial tensile load. The material property is graded for varying Young’s Modulus and Poisson’s Ratio with different composition of glass microballoons. Finally, a uniform pressure is applied at the top and the model is constrained with symmetric boundary conditions at the left and bottom. As the result, these numerical results for both SCF experimental and simulation model are compared to those obtained from analytic fracture mechanics procedures and are found to be varied. In addition, the SCF is sensitive to the modulus of elasticity, particularly for lower composition weight percentage (wt.%), while it is also varied with the different weight percentage (wt.%) of glass microballoons, which is led by 2 wt.% specimen.
{"title":"Analysis of stress concentration factor for tensile characteristics of syntactic foam using finite element method","authors":"Z. Salleh, Mainul Islam, J. Epaarachchi","doi":"10.6000/1929-5995.2017.06.01.4","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.01.4","url":null,"abstract":"This paper presented the stress concentration factor (SCF) around the half circular edge of tensile specimens \u0000made of syntactic foam using finite element software Strand7 software. The study is a preliminary effort, which investigates the effect of variations of crack geometry on the stress concentration factor on a tensile specimen subjected to a constant, uniform, uniaxial tensile load. The material property is graded for varying Young’s Modulus and Poisson’s Ratio with different composition of glass microballoons. Finally, a uniform pressure is applied at the top and the model is constrained with symmetric boundary conditions at the left and bottom. As the result, these numerical results for both SCF experimental and simulation model are compared to those obtained from analytic fracture mechanics procedures and are found to be varied. In addition, the SCF is sensitive to the modulus of elasticity, particularly for lower composition weight percentage (wt.%), while it is also varied with the different weight percentage (wt.%) of glass microballoons, which is led by 2 wt.% specimen.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"10 1","pages":"21-32"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79610125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-04-06DOI: 10.6000/1929-5995.2017.06.01.2
C. F. Bandeira, S. R. Montoro, S. T. Faria, P.R.S. Moreira, A. Pereira, L. Oliveira, A. Milanese
The increase in the disposal of new polymeric materials is growing considerably in recent years, causing a major environmental impact. In view of this factor, many researchers have been studying and producing biodegradable composites whose shorter time to degradation reduces the volume of waste in landfills. Reinforcements made from natural fibers, especially sisal, has been much used in these new composites due to their low density, because they are derived from renewable source, are not toxic and their low cost compared to synthetic fibers. In view of this need, this study evaluated an epoxy/sisal composite via TGA (Thermogravimetric Analysis), DSC (Differential Scanning Calorimetry), the impact resistance and the mass variation evaluation before and after exposure in simulated soil for a period of 8 weeks.
{"title":"Degradability of Epoxy/Sisal Fiber Composites via Simulated Soil","authors":"C. F. Bandeira, S. R. Montoro, S. T. Faria, P.R.S. Moreira, A. Pereira, L. Oliveira, A. Milanese","doi":"10.6000/1929-5995.2017.06.01.2","DOIUrl":"https://doi.org/10.6000/1929-5995.2017.06.01.2","url":null,"abstract":"The increase in the disposal of new polymeric materials is growing considerably in recent years, causing a major environmental impact. In view of this factor, many researchers have been studying and producing biodegradable composites whose shorter time to degradation reduces the volume of waste in landfills. Reinforcements made from natural fibers, especially sisal, has been much used in these new composites due to their low density, because they are derived from renewable source, are not toxic and their low cost compared to synthetic fibers. In view of this need, this study evaluated an epoxy/sisal composite via TGA (Thermogravimetric Analysis), DSC (Differential Scanning Calorimetry), the impact resistance and the mass variation evaluation before and after exposure in simulated soil for a period of 8 weeks.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"78 1","pages":"12-16"},"PeriodicalIF":0.0,"publicationDate":"2017-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80054668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-23DOI: 10.6000/1929-5995.2016.05.04.3
Mingsen Chen, H. Zhou, Xiaofang Li, Li Zhou, Faai Zhang
In this study, we used ethyl 2-bromopropionate (EBrP) as an initiator of activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) of methyl methacrylate (MMA). We investigated in detail the effect on polymerization of different kinds of reducing agents and ligands, the amounts of the reducing agent and catalyst, and reaction temperature. We determined the molecular weight and dispersity of the polymers by gel permeation chromatography (GPC). The results reveal glucose to be the best reducing agent for this system. The monomer conversion increased with increases in the reaction temperature and in the feeding amounts of the reducing agent and catalyst. The optimum amount of the reducing agent and minimal amount of catalyst required depend on the particular system. For example, we polymerized MMA with 200 ppm of catalyst and 15-fold of glucose/CuCl 2 resulting in a PMMA with high M n ( M n,GPC = 48 700, M n,theo = 48 500) and low dispersity (1.27). The first-order kinetics show that the molecular weights increased linearly with the monomer conversion and are consistent with the theoretical values, the chain extension reaction and end group analysis results also demonstrate that the characteristics of polymerization process belong to a typical “livingâ€/controlled radical polymerization. Moreover, 1 H-NMR analysis results indicate the stereoregularity of the polymer is given priority over syndiotactic architecture and the effect of the type of ligand on the stereoregularity is very slight.
{"title":"Optimizing Activators Regenerated by Electron Transfer for Atom Transfer Radical Polymerization of Methyl Methacrylate Initiated by Ethyl 2-bromopropionate","authors":"Mingsen Chen, H. Zhou, Xiaofang Li, Li Zhou, Faai Zhang","doi":"10.6000/1929-5995.2016.05.04.3","DOIUrl":"https://doi.org/10.6000/1929-5995.2016.05.04.3","url":null,"abstract":"In this study, we used ethyl 2-bromopropionate (EBrP) as an initiator of activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) of methyl methacrylate (MMA). We investigated in detail the effect on polymerization of different kinds of reducing agents and ligands, the amounts of the reducing agent and catalyst, and reaction temperature. We determined the molecular weight and dispersity of the polymers by gel permeation chromatography (GPC). The results reveal glucose to be the best reducing agent for this system. The monomer conversion increased with increases in the reaction temperature and in the feeding amounts of the reducing agent and catalyst. The optimum amount of the reducing agent and minimal amount of catalyst required depend on the particular system. For example, we polymerized MMA with 200 ppm of catalyst and 15-fold of glucose/CuCl 2 resulting in a PMMA with high M n ( M n,GPC = 48 700, M n,theo = 48 500) and low dispersity (1.27). The first-order kinetics show that the molecular weights increased linearly with the monomer conversion and are consistent with the theoretical values, the chain extension reaction and end group analysis results also demonstrate that the characteristics of polymerization process belong to a typical “livingâ€/controlled radical polymerization. Moreover, 1 H-NMR analysis results indicate the stereoregularity of the polymer is given priority over syndiotactic architecture and the effect of the type of ligand on the stereoregularity is very slight.","PeriodicalId":16998,"journal":{"name":"Journal of Research Updates in Polymer Science","volume":"10 1","pages":"149-157"},"PeriodicalIF":0.0,"publicationDate":"2017-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87556240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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