Raw Materials Of Drinking Straws
Drinking straws are made from a formulated blend of plastic resin, colorants, and other additives.
Plastic
Historically, straws have been made from paper but today polypropylene plastic is the material of choice. This resin is light-weight, has fair abrasion resistance, good dimensional stability, and good surface hardness. It typically does not experience problems with stress cracking and it offers excellent chemical resistance at higher temperatures. Most importantly for this application, it has good thermoplastic properties. This means it can be melted, formed into various shapes and, upon reheating, can be melted and molded again. Another key attribute of this plastic is that it is safe for contact with food and beverage.
Colorants
Colorants can be added to the plastic to give the drinking straws an aesthetically pleasing appearance. However, in the United States, the colorants used must be chosen from a list of pigments approved by the Food and Drug Administration (FDA) for food contact. If the colorants are not food grade, they must be tested to make sure they will not leach out of the plastic and into the food or beverage.
Other Additives
Additional materials are added to the plastic formula to control the physical properties of the finished straw. Plasticizers may be added to keep the resin from cracking. Antioxidants are used to reduce harmful interactions between the plastic and the oxygen in the air. Other stabilizers include ultraviolet light filters, which shield the plastic from the effects of sunlight and prevent the radiation from adversely effecting the plastic. Finally, inert fillers may be added to increase the bulk density of the plastic. All these materials must meet appropriate FDA requirements.