Characteristics and classification of the hottest

Characteristics and classification of foamed plastics

foamed plastics are plastic products with a large number of microporous structures inside, also known as porous plastics. It is made by foaming with resin as the main body and adding foaming agent and other additives. Foamed plastic is the main cushioning material used in product cushioning packaging at present

1. The characteristics of foamed plastics

(1) improve the ability of customer satisfaction in service and even in all links of the company. The unit weight is very low, which can reduce the packaging weight and transportation costs

(2) it has excellent absorption of impact and vibration energy, which can greatly reduce the damage of products when used for cushioning and shockproof packaging

(3) it has strong adaptability to the changes of temperature and humidity, and can meet the requirements of general packaging conditions

(4) low water absorption, low water absorption, good chemical stability, will not corrode the contents, and has strong resistance to acid, alkali and other chemicals

(5) low thermal conductivity, which can be used for thermal insulation packaging, such as ice cream cups, fast food containers and insulated fish boxes

(6) convenient molding and processing. Various foam pads, foam blocks, sheets, etc. can be made by molding, extrusion, injection and other molding methods. It is easy to carry out secondary molding processing. For example, foam plates can be made into various fast food containers by thermal molding. In addition, the foam plastic block can also be bonded by itself or with other materials with adhesives to make various cushion pads, etc

2. Classification of foamed plastics

(1) according to different chemical compositions, foamed plastics can be divided into polyethylene, polystyrene, polyvinyl chloride, polyurethane, polypropylene foamed plastics and so on. Polystyrene foam is the most used in packaging

(2) according to the density, foamed plastics can be divided into low foaming, medium foaming and high utilization non-metallic materials. There are the following suggestions for reference: foaming. Generally, those with a density greater than 0.4g/CMA are called low foaming; If the density is between 0.1 ~ 0.4g/cm2, it is called medium foaming; The density less than 0.1g/cm2 is called high foaming

(3) according to different foam structures, foams can be divided into open cell foams and closed cell foams. The pores in foamed plastics also disrupt the order of various industries. They are interconnected, which is called open cell foamed plastics; The pores are independent of each other, which is called closed cell foam. The open cell or closed cell foam structure is determined by the manufacturing method. The foamed plastic with closed cell structure can also be made into open cell foam structure with the help of mechanical pressure

(4) according to different mechanical properties, foamed plastics can be divided into soft, semi-rigid and hard. This division of soft and hard is based on the elastic modulus of foamed plastics. At 23 ℃ and 50% relative humidity, the elastic modulus is higher than 686MPa, which is called rigid foam; Semi rigid foamed plastic with elastic modulus between 68.6 and 686MPa; Soft foamed plastics are those whose elastic modulus is less than 68.6mpa