Plasticology 101

The 7 major plastic types are: HDPE, LDPE, PP, PVC, PET, PS and Other. Please see our glossary for additional definitions. Below we provide basic definitions and comparisons of each type of plastic.

PET recycling symbol
PET or PETE is of the polyester family and is used in beverage, food and other liquid containers. PET can be semi-rigid to rigid and is very lightweight. It acts as a good barrier to alcohol (requires additional “Barrier” treatment) and solvents. PET also has a good gas barrier and a fair moisture barrier. It is not good for strong bases or strong acids, however. It is strong, impact-resistant, and naturally colorless and transparent. PET has good stress crack and impact resistance at room temperature and above. Its SPI resin identification code number is 1.
Common uses: soft drink bottles, cooking oil bottles, peanut butter jars, products containing essential oils, some fruit juices, alcohol beverage bottles, space blankets, ketchup bottles, wine

HPDE is made from hydrocarbons found in petroleum. HDPE is flexible yet more rigid, has a stronger intermolecular force and tensile strength than low-density polyethylene (LDPE). It is also harder and more opaque and can withstand somewhat higher temperatures: 120 °C for short periods, 110 °C continuously. HDPE has a good impact strength, a good resistance to stress crack, chemicals and vapors. However, HDPE is a poor gas barrier. Its natural color is milky white and semi translucent depending on its density. Its SPI resin identification code number is 2.
Common uses: milk jugs, distilled water, large vinegar bottles, grocery bags, liquid laundry and dish detergent, fabric softener, motor oil, antifreeze, bleach and lotion

PVC is a widely used thermoplastic polymer. It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates.
Common uses: plastic pipes, outdoor furniture, shrink-wrap, water bottles, salad dressing containers, liquid detergent containers

LDPE is made from hydrocarbons found in petroleum. Its tensile strength and density is lower, but its resilience is higher than high-density polyethylene (HDPE). LDPE is very flexible and has a natural milky color and is translucent. LDPE has high impact strength, a good chemical resistance, and acts as a good barrier for water and alcohol. LDPE, however, is a poor gas barrier. It can withstand temperatures of 80 °C continuously and 95 °C for a short time. It can be translucent or opaque, is flexible, tough, and almost unbreakable. Its SPI resin identification code number is 4.
Common uses: dry-cleaning bags, produce bags, trash can liners, food storage containers, squeezable products

PP is often used for food packaging. It is not as tough as HDPE, but it is less brittle. PP is less flexible than LDPE, somewhat stiffer than other plastics, reasonably economical, and can be translucent, opaque, or of any color. Its natural color is opaque, natural grayish-yellow. PP has very good resistance to fatigue, stress crack, and impact. PP is an excellent moisture barrier, a good alcohol and oil barrier, but poor gas barrier. PP has a melting point of 320 °F (160 °C). Food containers will not melt in the dishwasher or during industrial hot filling processes. Its SPI resin identification code number is 5.
Common uses: bottle caps, drinking straws, hinged containers, battery cases, dairy tubs (e.g. sour cream, cottage cheese), cereal box liners

PS is made from petroleum. Pure solid polystyrene is a colorless, rigid plastic with limited flexibility. It can be cast into molds with fine detail. Polystyrene can be transparent or can be made to take on various colors. I has a good resistance to inorganic chemicals. It is light and heat stable and nontoxic. It has poor impact and stress crack resistance and poor barrier properties. Its SPI resin identification code number is 6.
Common uses: bottle caps, drinking straws

OTHER plastics can stand alone or be combined with any type of plastic, working together to form a new OTHER combination. Packaging that consists of two or more commonly used plastics, for instance a reusable beverage mug that is built from one type of plastic on the outside, but is lined with another falls into the OTHER category.
Common uses: acrylic in the form of contact lenses, dental fillings and paint.
This information is generalized. Each product packaged in plastic will have a slightly different reaction to the plastic. You are responsible for testing your product with your packaging. We offer samples for you to test your product with and therefore will not be accountable for any product-to-plastic incompatibilities.


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