Plastic specific gravity meter manufacturers analyze that due to the poor thermal conductivity of plastic, the inner layer of the plastic part slowly cools, forming a high-density solid layer with large shrinkage. So those with thick walls, slow cooling, and high-density layers will shrink more. In addition, the presence or absence of inserts, as well as the layout and quantity of inserts, directly affect the direction of material flow, density distribution, and shrinkage resistance. Therefore, the characteristics of plastic parts have a significant impact on the size and directionality of shrinkage. The highest temperature at which no flow occurs under a certain pressure.

1. Synthetic resin is the most important component of plastics, and its content in plastics is generally between 40% and 100%. Due to its high content and the fact that the properties of resin often determine the properties of plastic, people often consider resin as synonymous with plastic.

2. Fillers, also known as fillers, can improve the strength and heat resistance of plastics and reduce costs. Fillers can be divided into two types: organic fillers and inorganic fillers. The former, such as wood powder, shredded cloth, paper, and various textile fibers, while the latter, such as glass fiber, diatomaceous earth, asbestos, carbon black, etc.

3. Plasticizers can increase the plasticity and flexibility of plastics, reduce brittleness, and make plastics easier to process and shape. Plasticizers are generally high boiling organic compounds that are miscible with resins, non-toxic, odorless, and stable to light and heat. Phthalates are the most commonly used.

4. Stabilizers are added to plastics to prevent the decomposition and damage of synthetic resins caused by light and heat during processing and use, and to extend their service life. Commonly used ones include stearic acid salts, epoxy resins, etc.

5. Colorants can give plastics various bright and beautiful colors. Organic dyes and inorganic pigments are commonly used as coloring agents.

6. The function of lubricants is to prevent plastics from sticking to metal molds during molding, while also making the surface of plastics smooth and aesthetically pleasing. Common lubricants include stearic acid and its calcium magnesium salts.

7. Antioxidants prevent plastics from turning yellow or cracking due to thermal oxidation during heating molding or high-temperature use. In addition to the above-mentioned additives, flame retardants, foaming agents, anti-static agents, etc. can also be added to the plastics measured by the plastic densitometer to meet different usage requirements.