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PVDF Nano Composite Coatings Resistant to Ionizing Radiation
, M.Sc. Thesis Sharif University of Technology ; Forounchi, Massoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Poly (vinylidene Fluoride) (PVDF)/organoclay nanocomposite films were prepared via melt mixing, solution casting and Co-precipitation techniques. The effects of different kinds of nanoclay, sample preparation techniques and electron beam irradiation on PVDF/Nanoclay nanocomposite are reported in this research project. Differential scanning calorimetry was used to study thermal properties and crystallinity of the PVDF and its nanocomposites. The chemical and crystalline structure of the samples was analysed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) and the mechanical properties of the PVDF nanocomposite were characterized by stress strain test. The degree of...
Improve Performance of Polyamide Reverse Osmosis Membranes by Crosslinking Treatments
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Abbas (Supervisor)
Abstract
Reverse osmosis membranes are one of the most common methods of desalination of water in the world today. In the meantime, aromatic polyamide thin-film composite reverse osmosis membranes have one of the best performances and can be widely used in industry. This project aims to make surface modifications on the made raw membranes and increase the degree of crosslinking to improve the functional properties of the membrane, such as the percentage of salt rejection and the flux of permeate, and the reduction of fouling. For this purpose, polyvinyl alcohol and l-arginine along with maleic anhydride as the crosslinking agent and hexamethylene diisocyanate were used for surface modification of the...
Gelatin-g-poly(sodiumAcrylate-co-acrylamide)/kaolin superabsorbent hydrogel composites: Synthesis, characterisation and swelling behaviour
, Article Polymers and Polymer Composites ; Volume 15, Issue 5 , 2007 , Pages 395-402 ; 09673911 (ISSN) ; Hosseinzadeh, H ; Sharif University of Technology
Rapra Technology Ltd
2007
Abstract
A novel superabsorbent hydrogel composite based on gelatin has been prepared by graft copolymerisation of acrylic acid and acrylamide in the presence of kaolin powder, using methylene-bisacrylamide (MBA) as a crosslinking agent and ammonium persulfate as an initiator. The synthetic variables affecting the water absorbency of the resulting superabsorbent composite were studied and the composite structure was confirmed using FT-IR spectroscopy. A new absorption band at 1728 cm-1 in the composite spectrum confirmed the presence of a kaolin-organic polymer linkage. The effect of kaolin content and MBA concentration showed that increasing these parameters decreased the water absorbency of the...
MBA-crosslinked Na-Alg/CMC as a smart full-polysaccharide superabsorbent hydrogels
, Article Carbohydrate Polymers ; Volume 66, Issue 3 , 2006 , Pages 386-395 ; 01448617 (ISSN) ; Barzegar, Sh ; Mahdavinia, G. R ; Sharif University of Technology
2006
Abstract
A novel superabsorbent hydrogel composed of carboxymethylcellulose (CMC) and sodium alginate (Na-Alg) was prepared by using methylenebisacrylamide (MBA) as a crosslinking agent. Ammonium persulfate (APS) was used as an initiator. For investigation of the effect of reaction variables on water absorbency of the hydrogels, the synthetic conditions were systematically optimized through studying the influential factors, including temperature, Na-Alg/CMC weight ratio and concentration of MBA and APS. Increase in MBA and APS concentration results in the decrease in water absorbency of the hydrogels. The water absorbency of the hydrogels increased with increasing of reaction temperature and...
A convenient one-step preparation of chitosan-poly(sodium acrylate-co-acrylamide) hydrogel hybrids with super-swelling properties
, Article Journal of Applied Polymer Science ; Volume 99, Issue 4 , 2006 , Pages 1615-1619 ; 00218995 (ISSN) ; Pourjavadi, A ; Zohuriaan Mehr, M. J ; Sharif University of Technology
2006
Abstract
Hydrogel hybrids were conveniently prepared from alkaline hydrolysis of chitosan-poly(acrylonitrile) mixture under highly practical conditions. The reaction of chitosan alkoxide anions with nitrile groups of poly(acrylonitrile) (PAN) forms crosslinking points and results in a three-dimensional network with superswelling ability in aqueous media. The hydrogel hybrid was identified using FTIR spectroscopy. The PAN content of the hydrolyzing feed affects proportionally the swelling capacity of the hydrogel hybrid. The swelling properties (capacity and rate) of the ampholytic hydrogel were investigated preliminarily. © 2005 Wiley Periodicals, Inc
Chitosan-g-poly(acrylic acid)/kaolin superabsorbent composite: Synthesis and characterization
, Article Polymers and Polymer Composites ; Volume 14, Issue 2 , 2006 , Pages 203-211 ; 09673911 (ISSN) ; Mahdavinia, G. R ; Sharif University of Technology
Rapra Technology Ltd
2006
Abstract
A novel superabsorbent composite based on chitosan was prepared by graft copolymerization of acrylic acid (AA) in the presence of kaolin powder using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The synthetic variables (i.e. AA, MBA, and APS concentration, and the kaolin amount) affecting the water absorbency of the resulting superabsorbent composite were studied. Evidence of grafting and kaolin interaction was obtained by comparing the FTIR spectra of the initial substrates with that of the superabsorbent composite. A new absorption band at 1722 cm-1 in the composite spectrum confirmed the kaolin-organic polymer linkage. The effect of...
Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked ΚC-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties
, Article Journal of Applied Polymer Science ; Volume 98, Issue 1 , 2005 , Pages 255-263 ; 00218995 (ISSN) ; Hosseinzadeh, H ; Mazidi, R ; Sharif University of Technology
2005
Abstract
To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (ΚC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N′,N′-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N′-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for ΚC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,...
Effect of organoclay loading and electron beam irradiation on the physico-mechanical properties of low-density polyethylene/ethylene-vinyl acetate blend
, Article Polymers for Advanced Technologies ; Volume 22, Issue 12 , 2011 , Pages 2352-2359 ; 10427147 (ISSN) ; Behradfar, A ; Sheikh, N ; Sharif University of Technology
2011
Abstract
The influence of electron beam (EB) irradiation and organoclay (OC) loading on the properties of low-density polyethylene (LDPE)/ethylene-vinyl acetate (EVA) blends was investigated. The samples were subjected to the EB irradiation with the dose values of 50 and 250kGy. X-ray diffraction (XRD), gel content, mechanical, thermal, and electrical properties were utilized to analyze the characteristics of the LDPE/EVA blends with and without OC at different irradiation dosages. Gel content analysis showed that the OC promotes considerably the insoluble part so that the LDPE/EVA blends filled with OC become fully crosslinked at 250kGy; possibly through the formation of further crosslinks between...
Production of uniform size cell-enclosing silk derivative vehicles through coaxial microfluidic device and horseradish crosslinking reaction
, Article European Polymer Journal ; Volume 172 , 2022 ; 00143057 (ISSN) ; Hosseini, M ; Varaa, N ; Mahmoodi, N ; Goodarzi, A ; Taghdiri Nooshabadi, V ; Hassanzadeh, S ; Arabpour, Z ; Khanmohammadi, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Silk fibroin (SF) as a natural biopolymer holds great potential in biomedical research because of its biocompatibility, easy processability and high strength properties. However, slow gelation time has narrowed its applications, specifically in cell-laden microparticle production due to insufficient crosslinkable moieties. This study aimed to develop cell-laden silk fibroin-phenol (SF-Ph) microparticle through co-flow microfluidic system using SF conjugated Ph moieties whereas covalent crosslinking is mediated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H2O2). For this, the SF-Ph was synthesized through carbodiimide condensation crosslinking reaction. Aqueous...
Comparative Examination and Preparation of Polymeric Hydrogels in Order to use as Cellular Scaffold
, M.Sc. Thesis Sharif University of Technology ; Alemzadeh, Iran (Supervisor) ; Sharifi Aghdas, Farzane (Supervisor) ; Mashayekhan, Shohre (Supervisor)Three dimensional modeling of axonal microtubules
, Article 2014 21st Iranian Conference on Biomedical Engineering, ICBME 2014, 26 November 2014 through 28 November 2014 ; November , 2014 , Pages 298-302 ; 9781479974177 (ISBN) ; Shamloo, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2014
Abstract
Axon is a filament in neuronal system and axonal microtubules are bundles in axons. In axons, microtubules are coated with microtubule-associated protein tau, a natively unfolded profuse filamentous protein in the central nervous system. These proteins are responsible for the cross-linked structure of the axonal microtubule bundles. Through complimentary dimerization with other tau proteins, bridges are formed to nearby microtubules to create bundles. The transverse reinforcement of microtubules by cross-linking to the cytoskeleton has been shown to enhance their ability to bear compressive loads. Though microtubules are conventionally regarded as bearing compressive loads, in certain...
Pervaporation of toluene and iso-octane through poly(vinyl alcohol)/graphene oxide nanoplate mixed matrix membranes: Comparison of crosslinked and noncrosslinked membranes
, Article Journal of Applied Polymer Science ; Volume 135, Issue 7 , 2018 ; 00218995 (ISSN) ; Mohebbi, V ; Behbahani, R. M ; Ramazani S. A., A ; Sharif University of Technology
John Wiley and Sons Inc
2018
Abstract
Removal of aromatic compounds from fuel is an essential requirement in new environmental policies. In the present study, poly(vinyl alcohol)/graphene oxide (GO) mixed matrix membranes were prepared and applied to the separation of toluene from iso-octane by pervaporation, considering the similarity and interaction between graphene and aromatics. The effects of crosslinking and GO content on separation efficiency have been investigated in detail. Owing to the high affinity of GO with toluene through s and π bonds, the selectivity of the membranes was increased by incorporating a low amount of GO. The results also indicated that noncrosslinked membranes have higher selectivity and permeation...
Synthesis and properties of highly swelling PAAm/chitosan semi-IPN hydrogels
, Article Macromolecular Symposia ; Volume 274, Issue 1 , 2008 , Pages 171-176 ; 10221360 (ISSN) ; Pourjavadi, A ; Zohuriaan Mehr, M. J ; Sharif University of Technology
2008
Abstract
A semi-interpenetrating polymer network (semi-IPN) hydrogel composed of crosslinked chitosan and Polyacrylamide (PAAm) was prepared in the presence of formaldehyde as a crosslinker. The swelling capacity of hydrogel was shown to be affected by the crosslinker and the PAAm/chitosan ratio. The PAAm/chitosan semiIPN hydrogels are swelled at low pHs that attributed to both osmotic pressure and repulsion of -NH3+ groups on chitosan backbones. The swelling of hydrogel in acidic pHs showed that with increasing of chitosan content in the hydrogel, the swelling capacity was increased. But the swelling capacity of hydrogel in neutral pH is reversed, i.e. the higher the PAAm/chitosan ratio, the higher...
Synthesis, characterization, and swelling behavior of alginate-g- poly(sodium acrylate)/kaolin superabsorbent hydrogel composites
, Article Journal of Applied Polymer Science ; Volume 105, Issue 5 , 2007 , Pages 2631-2639 ; 00218995 (ISSN) ; Ghasemzadeh, H ; Soleyman, R ; Sharif University of Technology
2007
Abstract
A novel superabsorbent composite based on sodium alginate and the inorganic clay kaolin was synthesized via the graft copolymerization of acrylic acid (AA) in an aqueous medium with methylene bisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The effects of reaction variables, such as the MBA, AA, and APS concentrations and the alginate/kaolin weight ratio, on the water absorbency of the composite were systematically optimized. Evidence of grafting and kaolin interactions was obtained by a comparison of the Fourier transform infrared spectra of the initial substrates with that of the superabsorbent composite, and the hydrogel structure was confirmed...
Optimized synthesis of carrageenan-graft-poly(sodium acrylate) superabsorbent hydrogel using the Taguchi method and investigation of its metal ion absorption
, Article Polymer International ; Volume 56, Issue 2 , 2007 , Pages 283-289 ; 09598103 (ISSN) ; Amini Fazl, M. S ; Sharif University of Technology
2007
Abstract
The Taguchi method, a robust experimental design, was used for the optimization of the synthesis of a novel biopolymer-based superabsorbent hydrogel, carrageenan-graft-poly(sodium acrylate). The Taguchi method was applied for the experiment and standard 16 orthogonal arrays with five factors and four levels for each factor were used. In the synthesis of the superabsorbent hydrogel, N,N′-methylene bisacrylamide (MBA) was used as crosslinker, ammonium persulfate as initiator, and acrylic acid as monomer. Neutralization percent and reaction temperature were used as important factors. The analysis of variance results showed that the most important factor in this synthesis was MBA concentration....
Immobilization of cellulase on non-porous ultrafine silica particles
, Article Scientia Iranica ; Volume 14, Issue 4 , 2007 , Pages 379-383 ; 10263098 (ISSN) ; Kazemi, A ; Kheirolomoom, A ; Nejati, S ; Sharif University of Technology
Sharif University of Technology
2007
Abstract
The immobilization of cellulase onto non-porous ultrafine silica particles was studied. Cellulase was extracted from a Trichoderma reesei culture after partial purification with ammonium sulfate (pH = 5.0), which was then immobilized onto non-porous ultrafine silica particles, with or without the use of glutaraldehyde as a crosslinking agent. Cellulase was immobilized by adsorption onto ultrafine silica particles efficiently, as well as by covalent cross-linking with glutaraldehysde. Increasing the concentration of the free form of enzyme increased the amount of immobilized cellulase. The maximum enzyme immobilization happened at the free enzyme concentration of 0.48 mg/ml. In general, the...
Carrageenan-g-poly(sodium acrylate)/kaolin superabsorbent hydrogel composites: Synthesis, characterisation and swelling behaviour
, Article Polymers and Polymer Composites ; Volume 15, Issue 1 , 2007 , Pages 43-51 ; 09673911 (ISSN) ; Hosseinzadeh, H ; Mahdavinia, G. R ; Zohuriaan Mehr, M. J ; Sharif University of Technology
Rapra Technology Ltd
2007
Abstract
A novel superabsorbent hydrogel composite based on kappa-carrageenan (κC) was prepared by graft copolymerisation of acrylic acid (AA) in the presence of kaolin using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The synthetic variables (i.e. AA, MBA and APS concentration, and the amount of kaolin) affecting the water absorbency of the resulting superabsorbent composite were studied. Evidence of grafting and kaolin interaction was obtained by comparing the FTIR spectra of the initial substrates and of the superabsorbent composite. A new absorption band at 1722 cm-1 in the composite spectrum confirmed the kaolin-organic polymer linkage....
Optimization of synthetic conditions of a novel collagen-based superabsorbent hydrogel by Taguchi method and investigation of its metal ions adsorption
, Article Journal of Applied Polymer Science ; Volume 102, Issue 5 , 2006 , Pages 4878-4885 ; 00218995 (ISSN) ; Salimi, H ; Amini Fazl, M. S ; Kurdtabar, M ; Amini Fazl, A. R ; Sharif University of Technology
2006
Abstract
A novel biopolymer-based superabsorbent hydrogel was synthesized through chemical crosslinking by graft copolymerization of partially neutralized acrylic acid onto the hydrolyzed collagen, in the presence of a crosslinking agent and a free radical initiator. The Taguchi method, a robust experimental design, was employed for the optimization of the synthesis reaction based on the swelling capacity of the hydrogels. This method was applied for the experiments and standard L16 orthogonal array with three factors and four levels were chosen. The critical parameters that have been selected for this study are crosslinker (N,N′-methylene bisacrylamide), initiator (potassium persulfate), and monomer...
Electron beam induced crosslinking of nylon 6 with and without the presence of TAC
, Article Polymer Degradation and Stability ; Volume 89, Issue 3 , 2005 , Pages 436-441 ; 01413910 (ISSN) ; Frounchi, M ; Goudarzi, D ; Sharif University of Technology
2005
Abstract
The influence of electron beam irradiation on neat nylon 6 was manifested by formation of molecular branches deduced from increase in melt flow index and intrinsic viscosity. Crosslinking of nylon 6 was carried out using electron beam irradiation in presence of triallyl cyanurate (TAC). The crosslinked samples showed a high level of gel content. At a given dose, increasing the TAC level from 1% to 3% increased the gel content of the samples slightly and correspondingly decreased the percent of water absorption. The melting temperature decreased with increasing the dose and the TAC level. All samples containing TAC showed some decrease in crystallinity under exposure to electron beam. The...
Improvement in oil absorbency by using modified carbon nanotubes in preparation of oil sorbents
, Article Advances in Polymer Technology ; Volume 32, Issue 1 , 2013 ; 07306679 (ISSN) ; Doulabi, M ; Sharif University of Technology
2013
Abstract
This article reports the first oil-absorbent cross-linked copolymer consisting of modified multiwalled carbon nanotube (MWCNT) and showing high oil absorbency. Also, to investigate and evaluate the effective parameters on oil absorbency, cross-linked dodecyl methacrylate (DDMA)-diphenylacrylamide (DPAA) and DDMA-butyl acrylate (BA) copolymers were synthesized. DDMA was copolymerized with different mol% of DPAA or BA and cross-linked using azobisisobutyronitrile as the initiator and various weight percentages of 1,4-butandiol dimethacrylate, methylene bisacrylamide, or vinyl group-modified MWCNT cross-linkers. The effects of monomer feed composition, cross-linker concentration, and the...