Overview of foamed plastics
DATE：2022/6/13 8:48:12 / READ： / SOURCE：This station
Overview of foamed plastics
Definition of foamed plastic: foamed plastic is a plastic product based on resin, which contains numerous tiny bubbles inside. It is also called microporous plastic or porous plastic. Modern technology can process almost all thermosetting and thermoplastic resins into foamed plastics. The main varieties are polystyrene, polyethylene, polyvinyl chloride, polyurethane, phenolic, urea formaldehyde and other foamed plastics. Lithium battery diaphragm production line www.handern comClassification of foamed plastics: there are many classification methods for foamed plastics, and there are three common classification methods. (1) According to hardness classification, it can be divided into soft, hard and semi-hard. At 23 ℃ and 50% relative humidity, the elastic modulus of various foams is as follows. The elastic modulus of soft foams is less than 70MPa and that of hard foams is greater than 700MPa. The elastic modulus of semi-rigid foams is 70~700mpa (2) according to the density classification, it can be divided into low foaming, medium foaming and high foaming plastics. The density of various foams is as follows. Low hair foam plastic density 400kg/m ³ Above medium foamed plastic density 100~400kg/m3 high foamed plastic density 100kg/m ³ The following (3) can be classified into open cell and closed cell foams according to the cell structure. Lithium battery diaphragm production line www.handern com
Foamed plastic, also known as microporous plastic, is a plastic with numerous micropores in the whole. The vast majority of the bubbles contained are interconnected foams, which are called open cell foams. The foamed plastics containing most of the bubbles are disconnected from each other are called closed cell foamed plastics. The extrusion of foamed plastics is an important part of plastic extrusion process. Mixing gas into plastics can make plastic products have unique properties. Replacing some resins with low-cost gaseous fillers (gas) can greatly reduce the cost of materials. The comparison of open cell and closed cell foams is as follows. The open cell foams are connected with each other, and the closed cell foams are isolated, See Table 1-1 and Figure 1-1 for the classification and structure types of disconnected foams. Table 1-1 common foams classification: soft open cell closed cell open cell phenolic plastic polyvinyl chloride polyurethane polyvinyl chloride urea formaldehyde plastic polystyrene silicone plastic polyvinyl chloride sheet polyurethane polyvinyl formal polyethylene sheet cellulose acetate polyethylene urea formaldehyde plastic epoxy resin lithium battery diaphragm production line www.handern com
Characteristics of foamed plastics: as a kind of plastics, foamed plastics are composed of plastics and uniformly dispersed gases, so they have the following characteristics. ① Low density. There are a large number of bubbles in the foamed plastics with a density of about 10~500. The structural types of foamed plastics are as follows: (a) open cell structure; (b) closed cell structure; (c) Structural foam -- the same formula, special process, no foaming on the surface layer, foaming on the core layer; (d) Structural foam -- composite molding with different formulations; (e) Combined foam -- adding fibrous filler; (f) Combined foam -- add spherical filler kg/m ³ It is a fraction to dozens of non foaming plastic products. ② Good shock absorption. When the foam plastic is subjected to impact load, the gas in the cell is compressed by the load, and the external force disappears and rebounds. This compression and rebound will consume the impact load energy. ③ Excellent heat insulation. Because there are a large number of bubbles in the foam, the thermal conductivity of the gas in the bubbles is much lower than that of the plastic, so the thermal conductivity of the foam is very low. ④ Sound insulation effect is good. The sound insulation effect of foamed plastics is achieved by absorbing the energy of sound waves so that the sound waves cannot be reflected and transmitted. ⑤ High specific strength. Due to the low density of foamed plastics, the specific strength is naturally higher than that of non foamed products. The mechanical strength of foamed plastics decreases with the increase of foaming times. Generally, the strength of microcellular or microporous foamed plastics is high. Lithium battery diaphragm production line www.handern com
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