The addition of modified molecular weight antioxidants can prevent degradation of the polymer during processing and prevent oxidation of the finished product during use. Silver-loaded chromium phosphate antistatic additives are used in many packaging grades to reduce 99% inhibition of E. coli Staphylococcus aureus by bottles or packaging. Specific applications require special additive formulations, ranging from chemical to microbiological applications. Excellent weather resistance and anti-ultraviolet (or sunlight) can be achieved by adding anti-UV additives. Without the addition of UV-resistant or carbon black PE, it is recommended not to continue to use it outdoors.
More than 1/3 of HDPE sold in the United States is used for blow molding. These range from bottles containing bleach, motor oil, detergent, milk and distilled water to large refrigerators, automobile fuel tanks and canisters, which are also divided into different grades for industrial, food, and medical use. The characteristics of blow molding grades, such as melt strength, ES-CR and toughness, are similar to those used for sheet and thermoforming applications, so similar grades can be used.
Injection-blow molding is usually used to make smaller containers for packaging medicines, anti-acid barrels, shampoos and cosmetics. One advantage of this process is that the bottles are automatically trimmed; there is no need for post-finishing steps like general blow molding. Although there are some narrow MWD grades used to improve surface finish, medium to wide MWD grades are generally used.
