Plastic Bottles and Glass Bottles in Packaging
Plastic bottles and glass bottles are the most popular components of rigid packaging. There are 4 major types of glass used in modern packaging and plastic containers for packaging come in a variety plastic resins that vary in appearance, chemical capatability, functional use, and price.
Plastic Bottles: Materials
High, Medium, and Low Density Polyethylene (PE) Bottles
Plastic bottles are most commonly made from Polyethylene (PE) in high, medium and low density (HDPE, MDPE, and LDPE). The higher the density the more rigid the container is. Bottles that are made from PE that have no colorant added are called Natural as they are not clear like glass, but are transparent (see through). A good example of a natural container is most 1 gallon plastic milk jugs.
Polyethylene Terephthalate (PET) Bottles
Polyethylene terephthalate (PET), bottles are growing in popularity faster that any other material. PET is a plastic resin and a form of polyester. PET bottles and PET jars are becoming so popular because of its strength, thermo-stability and it incredible transparency since Natural PET can be as clear as glass.
Pet bottles are most commonly used in the food and beverage industry to package soda, water, juice, vegetable oils, salad dressings, peanut butter, and hundreds of other food and beverage products.
The personal care and cosmetic industry have switched much of what was previously packaged in glass to PET as it is inexpensive, lightweight making it easier to handle and cheaper to ship than glass as well as it being shatter-resistant and recyclable. It is less reactive and permeable to gas than its closest plastic counterpart Polyvinylchloride (PVC) so soda, beer, and water can be filled in PET bottles and what is inside does not get the plastic taste or lose the carbonation that would happen with other plastics bottles.
When Glycol modifiers are added to minimize brittleness and premature aging, the material is becomes PETG. It offers the most transparency of any type of PET, however PETGs water and gas transmission rates are not as good as PETE or even PVC. While PETE offers better transmission rates, its clarity is not as good as PETG.
Polypropylene (P/P) Bottles
Polypropylene (P/P) bottles are very similar to HDPE bottles. The only major exception is that polypropylene can be processed (clarified) in its natural uncolored state is more transparent or cleared than HDPE can be however it will never have the clarity that PET or PVC will have.
Polyvinylchloride (PVC) Bottles
Plastic bottles made from Polyvinylchloride (PVC) have dwindled somewhat in the past few years in popularity but are still an excellent choice for many personal care, cosmetic, and household chemicals due to the strength and transparency PVC has to offer. PVC recycling unfortunately is not nearly as popular as PET, P/P, and HDPE recycling, so some environment concerns do exist.
Glass Bottles: Glass Types and Materials
Types I, Type II, and Type III glass containers are all suitable for parenteral (injection or intravenous) preparations as specified by the U.S. Pharmacopoeia on the basis of chemical durability tests.
Type I Glass:
Type I glass bottles are made from borosilicate, which have has a highly resistant composition and releases the least amount of alkali. It is commonly used for pharmaceutical or fine chemical products that are sensitive to PH changes.
Type II Glass:
Type II glass containers are made from commercial soda lime glass that has been de-alkalized to obtain a great improvement in chemical resistance by treating the interior surfaces at a high temperature to eat away the alkali on or near the glass surfaces. The undesirable characteristic of Type II Glass is that the treating etches the surface, causing a frosted appearance.
Type III Glass:
Type III glass bottles and containers are made of untreated commercial soda-lime glass and has average or somewhat above average chemical resistance. It is the most common in use and is compatible with most items such as: food; beverages; common chemicals, etc.
Type NP Glass:
Untreated glass containers made of ordinary soda-lime glass. This glass cannot be used for parenteral preparations.
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