Plastic composition and formulation
Plastic is a polymer material composed of multiple components, primarily synthetic resins, along with various additives. These components work together to give plastics their diverse properties and uses. Synthetic resins are the plastic’s matrix, determining their basic properties, such as plasticity, strength, and heat resistance. Common synthetic resins include polyethylene, polypropylene, polyvinyl chloride, and polystyrene. Different synthetic resins have varying molecular structures and properties, giving plastics a diverse range of characteristics. For example, polyethylene, with its excellent flexibility and chemical resistance, is commonly used in the production of plastic films and containers; while polyvinyl chloride, with its high hardness and flame retardancy, is widely used in the production of pipes and sheets.
In addition to synthetic resins, plastics also contain fillers, whose primary function is to improve the plastic’s performance and reduce its cost. Fillers can be categorized as organic and inorganic. Inorganic fillers, such as calcium carbonate, talc, and glass fiber, are more widely used. Calcium carbonate improves the hardness and wear resistance of plastics while reducing production costs; talc improves their processing properties and heat resistance; and glass fiber significantly enhances their strength and rigidity, enabling their use in applications requiring high strength, such as automotive parts and building materials.
Plasticizers are also one of the common additives in plastics. Their main function is to increase the flexibility and plasticity of plastics and reduce the hardness and brittleness of plastics. Plasticizers are usually used in plastics such as polyvinyl chloride, because polyvinyl chloride without plasticizers is hard and difficult to process into products with a certain degree of flexibility. For example, when making plastic films, artificial leather and other products, it is necessary to add an appropriate amount of plasticizer to give the plastic good ductility and elasticity. Commonly used plasticizers include phthalates, aliphatic dibasic acid esters, etc., but it should be noted that some plasticizers may pose potential hazards to human health and the environment, so their amount and type need to be strictly controlled during use.
Stabilizers play a crucial role in the processing and use of plastics. They prevent degradation and aging under conditions such as high temperatures, light, and oxidation, thereby extending the plastic’s service life. Stabilizers can be categorized as heat stabilizers, light stabilizers, and antioxidants, depending on their mechanism of action. Heat stabilizers are primarily used to prevent plastics from decomposing due to high temperatures during processing. For example, polyvinyl chloride (PVC) is susceptible to thermal decomposition during processing, necessitating the addition of heat stabilizers such as lead salts and metal soaps. Light stabilizers absorb ultraviolet light, protecting plastics from aging caused by UV radiation, and are commonly used in plastic products used outdoors. Antioxidants inhibit plastic oxidation reactions, slowing the aging process.
The preparation of plastics is a complex process that requires mixing, stirring, and processing various ingredients in certain proportions based on the performance requirements of the desired plastic. First, the type of synthetic resin and the type and amount of various additives need to be determined based on the use and performance indicators of the plastic. Then, the synthetic resin, filler, plasticizer, stabilizer and other ingredients are placed in a mixing device and fully mixed to ensure that the various ingredients are evenly dispersed. The mixed material also needs to undergo processes such as plasticization and granulation to make granular plastic raw materials for subsequent molding processes such as injection molding and extrusion. During the preparation process, the proportion of each ingredient and the mixing process parameters need to be strictly controlled to ensure that the performance of the plastic meets the design requirements. Different plastic preparation formulas and processes will produce plastic products with different performance to meet the application needs of different fields.
