Abstract: A process for purifying a substantially unoriented polymer containing an impurity by means of ultrasonic leaching or extraction is described. The process involves contacting a substantially unoriented polymer containing an impurity with a cavitatable liquid, subjecting the substantially unoriented polymer containing an impurity in contact with a cavitatable liquid to ultrasonic radiation at a frequency and intensity sufficient to extract the impurity from the substantially unoriented polymer to form a purified substantially unoriented polymer, and then separating the purified substantially unoriented polymer from the cavitatable liquid containing the extracted impurity. A purified substantially unoriented polymer prepared by such a method is also described.