Sharif Digital Repository

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... 

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... 

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... 

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... 

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  

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... 

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... 

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... 

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... 

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... 

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...