The quality of plastic products mainly refers to the appearance and physical and mechanical properties of the products, and the chemical properties or hygienic requirements of some products must also be considered. Due to the different raw materials, structure and use of daily-use plastic products , its physical and mechanical properties are not the same. Only a few commonly used test indicators are introduced here.
1. Specific gravity: Each plastic has a certain range of specific gravity. For the same volume of plastic, the weight is heavy, on the contrary, the specific gravity is small and the weight is light. For example, the same size, volume of plastic cups, polypropylene (specific gravity of 0.90-0.91) cups are lighter than polyethylene (specific gravity of 0.91 to 0.96) cups. Where the specific gravity is greater than one, the product sinks into the water, and if the specific gravity is less than one, the product floats on the water.
2. Tensile strength: Tensile strength refers to the stress that a plastic per unit area can withstand when it is pulled off within a specified time. Its unit is kg/cm2. For a rope of the same thickness, the higher its tensile strength, the greater the tensile force it can withstand.
3. Elongation at break: Different products have different requirements for elongation at break. The elongation at break is large and the elasticity of the product is high. For plastic shoes, it is expected to be highly elastic and comfortable to wear. Therefore, a large elongation at break is required. For plastic ropes, it is required to have a small elongation at break so that the articles can be bundled tighter.
4. Hardness: Hardness generally refers to the hardness of the plastic surface. Take the plastic soles, it’s too hard to wear, it’s too soft, and wearing shoes on the gravel road will also hurt the soles of the feet. Therefore, the plastic sole is specified at the factory, its hardness can not be greater than seventy-five degrees (Shore). In this way, the shoes can be soft and moderate, and comfortable to wear.
5. Abrasion resistance: Plastic shoes, like other shoes and rubber shoes, wear gradually when the soles are often connected to the rough ground. Good quality shoes are more wear-resistant and take longer to wear. Therefore, when consumers buy shoes, the first concern is whether the shoes are resistant to wear and how long they can be worn. In this way, the manufacturer must determine the wear resistance of the shoes in order to ensure that the shoes have a certain wearing time and improve the quality of the products. performance.
The appearance of daily-use products is generally identified by methods such as seeing the hand mask. The inherent physical and mechanical properties of the product must be tested by a method specified by the state to assess the physical and mechanical properties of various plastic products. Understanding the above indicators will allow you to select better quality plastic products.
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