Search for: thermoplastics
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    Development of biodegradable food packaging plastic films

    , Article Iranian Journal of Science and Technology, Transaction B: Technology ; Volume 27, Issue 2 , 2003 , Pages 299-304 ; 03601307 (ISSN) Frounchi, M ; Dadbin, S ; Karimi, S ; Sharif University of Technology
    Biodegradable thermoplastic films suitable for use in food packaging were produced. These films were mainly based on thermoplastic starch. The major task included research into thermal conversion of starch in a compression molding process and also under high shear conditions in an extruder in the presence of suitable plasticizers. The destruction of crystalline structure resulted in amorphous structure with thermoplastic properties. Films were rather transparent but slightly brown in color and had a specific smell. The films showed sufficient plasticity and acceptable tensile strength and elongation. The effect of plasticizer content on the final properties of the film was investigated. The... 

    Development of co-continuous morphology in epoxy poly(methyl methacrylate) (PMMA) blends cured by mixtures of phase-separating and non-phase-separating curing agents

    , Article Colloid and Polymer Science ; Volume 283, Issue 2 , 2004 , Pages 145-153 ; 0303402X (ISSN) Rastegar, S ; Mohammadi, N ; Bagheri, R ; Sharif University of Technology
    The morphology of a quaternary blend containing a diglycidyl ether of bisphenol-A (DGEBA), a thermoplastic modifier (PMMA), a phase-separating curing agent (diaminodiphenylmethane, DDM), and a non-phase-separating curing agent (methylenebis(3-chloro-2,6-diethylaniline, MCDEA) was studied as a function of volume fraction of the thermoplastic modifier and fractional concentration of the curing agents in their mixture. It was found that using mixtures of curing agents a co-continuous morphology could be obtained at PMMA concentrations as low as 2.5 volume percent. Using FTIR spectroscopy it was proved that specific interactions are present between PMMA and individual amine curing agents. On the... 

    Preparation and Investigation of Behavior of Silica Nano Composites with TPU/PP

    , M.Sc. Thesis Sharif University of Technology Meshkati, Erfan (Author) ; Ramazani Saadatabadi, Ahmand (Supervisor)
    Blending can be used as one of the ways of producing materials with appropriate properties, which have many relative advantages in comparison with other methods like polymerization. Among the existing blends in the market and scientific areas, blends of polyurethane thermoplastic and polypropylene have been also studied because of its commercial importance and scientific interest. This blending can improve the mechanical properties, friction resistance, improvement of impact strength at low temperatures and improvement of plasticity properties. In this research, blends with different ratios of TPU/PP is produced by melt mixing, and for improving properties of blends, two kinds of nano fumed ... 

    Preparation and Investigation of Behavior of PLA/TPS Nanocomposite

    , M.Sc. Thesis Sharif University of Technology Akbari, Mohammad Amin (Author) ; Ramazani Saadat Abadi, Ahmad (Supervisor)
    With the environmental concerns and scarce supply of the crude oil, a revival in the development of bio-based and compostable materials is coming. They are in general being called the ''green'' materials, among which poly(lactic acid) (PLA) got the most extensive attention due to its good combined properties, including the renewable feedstock, the compostability, and its good mechanical properties, especially the young's modulus and stiffness. PLA has found numerous applications. It is considered having the highest potential to replace some regular petroleum based plastics. However PLA has its own shortcomings, its brittleness, low heat distortion temperature and relatively high cost witch... 

    Processing and Modification of Structure and Properties of Biodegradable Alloy based on Starch and Poly Lactic Acid

    , M.Sc. Thesis Sharif University of Technology Esmaeili, Mohsen (Author) ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
    In the recent years, the enhancing of utilization of polymeric materials, especially in packaging application, became the serious concern because of the problems of their recycling. One of efficient ways for solving this problem is usage of biodegradable polymers. Thermoplastic starch (TPS) is one the alternative materials which is produced in gelatinization process by plasticizers. However, using of TPS because of its low mechanical properties, poor processability and high water absorption is not applicable and it is necessary to improve that. One of the strategy in order to improving the TPS properties is blending with other polymers, such as polylactic acid (PLA) which the biodegradable... 

    Investigation and modeling of the thermal conductivity of PP/clay nanocomposites and PP/MWCNT nanocomposites

    , Article E-Polymers ; Dec , 2010 ; 16187229 (ISSN) Shahryar Nejad, S ; Golzary, A ; Sharif University of Technology
    In this study, polypropylene/clay nanocomposites were prepared by melt blending method and their thermal conductivity and the thermal conductivity of polypropylene/multi-wall carbon nanotube (MWCNT) nanocomposites were investigated and modeled. It is found that the thermal conductivity of the PP/Clay and PP/MWCNT nanocomposites is increased with increasing temperature. The thermal conductivity of the nanocomposites is improved due to incorporation of nanoclay and MWCNT compared with pure PP matrix  

    Fabrication and Characterization of Nanocomposite Bone Scaffold with Gradient Structure Based on Thermoplastic Starch

    , M.Sc. Thesis Sharif University of Technology Mirab, Fereshteh (Author) ; Bagheri, Reza (Supervisor)
    Tissue regeneration by bio-compatible/degradable scaffolds is one of the widely used approaches in the field of tissue engineering. In this study, a thermoplastic starch based nanocomposite scaffold with gradient structure was fabricated by unidirectional freeze drying method. To increase the stability of the scaffold in the aqueous media, PVA was added to starch solution. Then, the PVA and starch molecules were cross-linked by adding citric acid to the mixture. On the one hand, to improve the mechanical properties of the scaffold, and control its bio-degradability on the other, cellulose nano-fibers were employed. Also, the bioactivity of the scaffold was induced by using hydroxyapatite... 

    Study on Effects of Short Wood Fibers on Physical and Mechanical Properties of Biodegradable Composite Based on Thermoplastic Starch

    , M.Sc. Thesis Sharif University of Technology Pesaran Haji Abbas, Ehsan (Author) ; Bagheri, Reza (Supervisor) ; Sayyed Reihani, Morteza (Supervisor)
    Due to the negative effects of conventional plastics on the enviroment, especially in the packaging sector, extensive efforts have been put to replace these polymers with biodegradable polymers. Starch is one of the biodegradable polymers which has attracted a lot of attentions because of low cost and good processability. Native starch has the form of granule and can be processed to a continuous phase after gelatinization in the presence of a plasticizer. The resulting material is a biodegradable plastic-like material called thermoplastic starch (TPS) which is processed using conventional technologies, but suffers from low mechanical properties and high hydrophilicity. Addition of natural... 

    Preparation and Study of parameters of Biodegradable Starch/PLA Composite Reinforced with Nano Graphen Particles

    , M.Sc. Thesis Sharif University of Technology Abbasyan, Payam (Author) ; Ramezani Saadat, Ahmad (Supervisor) ; Shojaei, Akbar (Supervisor)
    There are so many problems in using of petroleum-based polymers such as their stability in the environment. According to the research carried out on this problem, one of the best ways to overcome this hardship is using of bio-based polymers. The most important bio-based polymer is polylactic acid. The very polymer enjoys the best mechanical properties but it is so expensive that make it impossible to afford. Therefore, in this project, a nano-composite structure of polylactic acid with thermoplastic starch reinforced with nano-particles was produced. After manufacturing, the process of mixture and the best percent for the very mixture for its use in packaging industry were investigated  

    Evaluation of Nanobiocomposite Based on Thermoplastic Starch for Bone Tissue Engineering Applications

    , M.Sc. Thesis Sharif University of Technology Taherimehr, Marzieh (Author) ; Bagheri, Reza (Supervisor) ; Maddah Hosseini, Hamid Reza (Supervisor)
    Development of new engineered materials for bone tissue engineering applications is rapidly growing. The most important characteristics of materials, which can be used for bone tissue engineering applications, are appropriate mechanical properties, degradation rate, swelling behavior, and bioactivity. The goal of the current investigation is to study the feasibility of incorporating a modified nano-biocomposite based on biodegradable thermoplastic starch for bone tissue engineering. Nano particles of ?-tricalcium phosphate and hydroxyapatite were incorporated for reinforcing the matrix as well as improving the bioactivity. A second biodegradable polymer, i.e. polycaprolactone, was used... 

    Push-out tests on polypropylene concrete

    , Article 11th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC-11, Taipei, 19 November 2008 through 21 November 2008 ; 2008 Maleki, S ; Mahoutian, M ; Sharif University of Technology
    The results of several monotonioc push-out tests on polypropylene concrete with channel shear connectors are presented in this research. The results are compared with ordinary concrete specimens with the same test setup. The effect of confining reinforcement on the shear capacity and ductility of polypropylene concrete composite system is investigated  

    Study on Effect of Chemical Parameters on Mechanical and Morphological Properties of Biodegradable wo Phase Propylene/Starch Blends

    , M.Sc. Thesis Sharif University of Technology Dorri Moghadam, Afsaneh (Author) ; Bagheri, Reza (Supervisor)
    In recent years the rapid rise of polymer consumption especially in the form of packaging materials became a real menace for the environment. Polyolefin are some of the most dominant packaging materials and responsible by part of the problems in the disposal of one-trip packaging. One of the possible ways of solving this problem is the introduction of additives increasing their susceptibility to environmental degradation into non-biodegradable polymers. One such additive is starch- the natural, cheap, and easily biodegradable polymer. Starch was already used as a filler or as a blend with polyolefin. Addition of dry starch granules to polyolefin follows the general trend of filler effects on... 

    Fabrication and Assessment of Physical and Mechanical Properties of Thermoplastic Starch/ Cellulose Nanofibers Biocomposites

    , M.Sc. Thesis Sharif University of Technology Ghasemi, Amir (Author) ; Bagheri, Reza (Supervisor)
    Due to the negative effects of conventional plastics on the environment, especially in the packaging sector, extensive efforts have been put to replace these polymers with biodegradable polymers. Starch is one of the biodegradable polymers which has attracted a lot of attentions because of low cost and good process ability. Native starch has the form of granule and can be processed to a continuous phase after gelatinization in the presence of a plasticizer. The resulting material is a biodegradable plastic-like material called thermoplastic starch (TPS) which is processed using conventional technologies, but suffers from low mechanical properties and high hydrophilicity. Addition of... 

    The study of Structure and Mechanical Properties of Thermopelastic Starch/Polyethylene alloy Nanocomposite Reinforced by Nanoclay

    , M.Sc. Thesis Sharif University of Technology Amiri, Mohammad (Author) ; Bagheri, Reza (Supervisor) ; Faghihi Sani, Mohammad Ali (Supervisor)
    Recently, due to the increase of environmental concerns, a significant raise in applying films and packaging containers, pollution produced from petroleum-based plastics packaging and problems arising from the various methods of waste disposal, the researchers have concentrate to replace these materials with biodegradable ones. In this study, a nanocomposite based on alloy matrix of thermoplastic starch and polyethylene which is reinforced with different amounts of Montmorillonitenanoclay has been constructed by the extrusion process. Furthermore, in order to increase the compatibility between the polar and non-polar components in the group of samples, compatibilizer was used and its... 

    Study on the Exfoliation of Graphite into Graphene by Electrochemical Method and Its Application in Thermoplastic Polyurethane Nanocomposite

    , M.Sc. Thesis Sharif University of Technology Razeghi, Mohammad Ali (Author) ; Pircheraghi, Gholamreza (Supervisor)
    Graphene is two dimensional nanomaterial, single layer of carbon atoms that exhibited excellent properties like high electrical conductivity and stiffness, but producing graphene and obtaining a good dispersion of graphene in a polymer matrix is still a major challenge. In this study by using the electrochemical route several graphene with different degree of oxidation produced in different electrolyte medium. According to XRD data, product of electrochemical exfoliation in dilute HNO3 medium includes 50% few-layer graphene (5 layers) and 25% GO and the rest are multi-layer graphene. Nonsolvent induced phase separation method were used to prepare TPU/Graphene nanocomposite. Different methods... 

    Wall thickness optimization of thick-walled spherical vessel using thermo-elasto-plastic concept

    , Article International Journal of Pressure Vessels and Piping ; Volume 82, Issue 5 , 2005 , Pages 379-385 ; 03080161 (ISSN) Kargarnovin, M. H ; Rezai Zarei, A ; Darijani, H ; Sharif University of Technology
    A study of thick-walled spherical vessels under steady-state radial temperature gradients using elasto-plastic analysis is reported. By considering a maximum plastic radius and using the thermal autofrettage method for the strengthening mechanism, the optimum wall thickness of the vessel for a given temperature gradient across the vessel is obtained. Finally, in the case of thermal loading on a vessel, the effect of convective heat transfer on the optimum thickness is considered, and a general formula for the optimum thickness and design graphs for several different cases are presented. © 2004 Elsevier Ltd. All rights reserved  

    Melt compounding of thermoplastic polyurethanes incorporating 1D and 2D carbon nanofillers

    , Article Polymer - Plastics Technology and Engineering ; Volume 56, Issue 7 , 2017 , Pages 732-743 ; 03602559 (ISSN) Yuan, D ; Pedrazzoli, D ; Pircheraghi, G ; Manas Zloczower, I ; Sharif University of Technology
    Taylor and Francis Inc  2017
    Thermoplastic polyurethane nanocomposites incorporating carbon nanotubes and graphene nanoplatelets were prepared through melt blending and compression molding, and the compounding process was optimized taking into account the different physical properties of one-dimensional carbon nanotubes and two-dimensional graphene nanoplatelets. Filler dispersion was further improved in the case of carbon nanotubes by noncovalent surface modification using a specific surfactant. The well-dispersed nanofillers favored enhanced phase separation in the thermoplastic polyurethane, leading to a better microstructure, which is able to improve the load transfer and maximize the tensile and viscoelastic... 

    Poly(lactic acid)/coplasticized thermoplastic starch blend: Effect of plasticizer migration on rheological and mechanical properties

    , Article Polymers for Advanced Technologies ; Volume 30, Issue 4 , 2019 , Pages 839-851 ; 10427147 (ISSN) Esmaeili, M ; Pircheraghi, G ; Bagheri, R ; Altstädt, V ; Sharif University of Technology
    John Wiley and Sons Ltd  2019
    Polylactic acid (PLA) and thermoplastic starch (TPS) are known as bio-based and biodegradable thermoplastic polymers that can be used in different applications owing to their inherent physical and mechanical properties. In order to reduce the higher costs of PLA and tuning its physical and mechanical properties suitable for short life packaging applications, blending of PLA with the TPS, more economical biodegradable polymer, has been considered in academic and industrial researches. However, melt blending of PLA with TPS without compatibilization process caused some drawbacks such as coarsening morphology and declining mechanical properties and ductility because of thermodynamic... 

    Fabrication and Characterization of Thermoplastic Starch Based Nanocomposite for Bone Scaffold

    , M.Sc. Thesis Sharif University of Technology Mahdieh, Zahra (Author) ; Bagheri, Reza (Supervisor)
    This project aimed to fabricate the bone scaffolds with applying thermoplastic starch-based nano-biocomposites. The starting materials for this scaffold are as follows: thermoplastic starch, ethylene vinyl alcohol as the polymer matrix and nanoforsterite as the ceramic reinforcing phase. Furthermore, vitamin E was used as antioxidant for preserving starch against thermo-mechanical degradations. Likewise, 3D pore structure was developed using azo-dicarbonamide and water in injection moulding process. With blending thermoplastic starch and ethylene vinyl alcohol, some thermoplastic starch’s properties including degradation rate and water absorption were modified. In addition, having... 

    Fabrication and Characterization of Polyethylene/Thermoplastic Starch Nanocomposite Films Containing Ethylene Adsorbent Nanostructures for Atmosphere-Controlled Packaging

    , M.Sc. Thesis Sharif University of Technology Sharifi, Mina (Author) ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
    In this research, a polyethylene / thermoplastic film containing ethylene adsorbent nanostructure was fabricated to package agricultural products and increase the shelf life of fruits and vegetables. The thermoplastic starch containing 60 wt% starch and 40 wt% plasticizers with weight ratios of 5: 1, 4: 1, and 3: 1 sorbitol to glycerol was added to the polyethylene film to determine the composition of the final film. The film was prepared by a combination of low-density polyethylene with 10wt % linear low-density polyethylene, 30 wt% thermoplastic starch (4: 1 sorbitol to glycerol ratio), and 3wt% PE-g-MA as compatibilizer. Then, halloysite nanotubes were added to the film as ethylene...