Applications of Different Plastic Materials
Plastics are everywhere in our life, but do you really know plastics? Today, we are going to learn plastic products
in our life. What kinds of materials are they made of ?
There is a sign at the bottom of each plastic container. It is a triangle with arrows, and there is a number in the triangle. The number one represents PET; the number two represents HDPE, the number three represents PVC; the number four represents PE; the number five represents PP; the number six represents PS and the number seven represents other plastic materials.
Beverage bottles and travel bottles are often made of PET. Their highest heat resisting temperature is 65 ℃ and their lowest heat resisting temperature is -20℃, which make them only suitable for warm drinks or frozen drinks. If plastic bottles made of PET are filled with high temperature liquid or heated, the harmful substances will come out.
HDPE ( high density polyethylene )
Containers for detergents, shampoos, body shampoos, edible oil, pesticides and military products are made of HDPE. Containers made of HDPE are opaque, and their surfaces are like wax. Because the container is difficult to be washed, it is not recommended recycling it.
The common products made of PVC are raincoats, building materials and plastic film, and PVC is rarely used for food packaging. This kind of material has excellent plasticity and is cheap, which make PVC widely used.
LDPE (low density polyethylene)
Plastic bags which can be seen everywhere are made of LDPE.
PP materials are commonly used in the manufacture of buckets, trash cans, baskets and food containers used for microwave ovens. The melting point of the pp material is up to 167 ℃. It is the only plastic box which can be put into the microwave oven, and it can be repeatedly used after it is cleaned.
PS has low water absorption, and it is often used for manufacturing building materials, toys, stationery, cups, boxes and disposable tableware for fast food restaurants. PS is a kind of material which is heat-resistant and cold-resistant, but it can not be put in a microwave oven so as to prevent released chemicals due to too high temperature. When the temperature is 70 °C, the chemical will be released. Therefore, PS is often applied to some containers.
PC is one of the most widely used plastic materials. PC has a high degree of transparency and free dyeing. It is tasteless and odorless. It is not harmful to humans' health and conforms to health and safety. Nursing bottles, space bottles, hair dryers, computers and shells of computers' accessories are made of PC materials in our daily life. The back cover of the iphone5c is also made of this kind of material.