Thermoplastic starch is a biodegradable and environmentally friendly alternative to petroleum-based plastics. It can be produced from a renewable resource (starch) and can decompose into water and carbon dioxide after use. The use of thermoplastic starch reduces the amount of non-biodegradable plastic waste in the environment, which can have a positive impact on the environment.
What is thermoplastic starch?
Thermoplastic starch is a modified form of starch that has been chemically or physically modified to exhibit thermoplastic behavior. It is a low-cost, biodegradable, and renewable alternative to synthetic thermoplastics, and can be used in a variety of applications, including food packaging, agriculture, and biomedical devices. The thermoplasticity of starch is achieved by altering its molecular structure, typically through cross-linking or the addition of plasticizers, which increases its viscosity and reduces its tendency to retrograde. This allows thermoplastic starch to be processed and molded at high temperatures, giving it properties similar to those of traditional petroleum-based plastics.
Thermoplastic starch production
Thermoplastic starch (TPS) is produced by heating and plasticizing starch granules in the presence of water, a plasticizer, and a small amount of an enzyme that enhances molecular bonding. This process results in a thermoplastic material that can be molded, extruded, or cast into various shapes and products. TPS production is considered environmentally friendly due to its biodegradability, compostability, and the use of renewable resources. Additionally, TPS production typically consumes less energy compared to synthetic plastic production and generates less waste and emissions.
Microstructure
The microstructure of thermoplastic starch (TPS) refers to the organization and arrangement of its constituent molecules and particles at a microscopic scale. The TPS microstructure can be influenced by several factors, including processing conditions, raw materials, and additives. The TPS microstructure affects its mechanical, thermal, and rheological properties, and therefore influences its potential applications and performance in various industries, such as packaging and biodegradable materials.
Morphology of TPS films
The morphology of thermoplastic starch films is characterized by its physical structure, including its grain size, porosity, orientation, and crystal structure. The properties of the film are influenced by factors such as the processing conditions, the type of starch used, and the presence of any additives. In general, the microstructure of thermoplastic starch films is highly dependent on the processing conditions, with the degree of crystallinity, orientation, and porosity affecting the properties such as tensile strength, elasticity, and barrier properties.
Crystallinity
Crystallinity refers to the degree of the ordered arrangement of the molecules in a material. In thermoplastic starch, the crystalline regions are composed of tightly packed starch molecules, while the amorphous regions consist of less ordered molecules. The extent of crystallinity in thermoplastic starch can affect its physical and mechanical properties, such as its strength, toughness, and transparency. The high crystallinity in thermoplastic starch is generally desirable for applications where good mechanical properties are required.
Mechanical properties
Thermoplastic starch has mechanical properties such as tensile strength, modulus of elasticity, toughness, and elongation at break. These properties are affected by the processing conditions, such as heating and cooling rate, and by the addition of plasticizers or other components. The mechanical properties of thermoplastic starch can be improved by blending with other polymers or by adding reinforcing agents, such as fillers or fibers. The resulting composite materials have potential applications in packaging, biodegradable products, and biomedical materials.
Aging
Thermoplastic starch (TPS) is a type of starch that has been modified to have thermoplastic properties, meaning it can be melted and molded when heated and solidifies when cooled. Aging can affect the mechanical properties of TPS, such as tensile strength, toughness, and elasticity, as well as its thermal properties, such as melting temperature and crystallinity. The aging process can cause changes in the molecular structure of TPS, which can lead to a decline in its properties. The exact changes that occur during aging depend on several factors, such as temperature, humidity, and the type of TPS. To maintain the desired properties of TPS, it is important to store it in a controlled environment and to use it within a specified shelf life.