it is up to the concentration of IPA (isolated purified a-??, 间苯二甲酸)for the concentration of 0.25%, the intenerated temperature is as high as more than 90 degree centigrade(used for hot-bottling beverage like milk/juice/tea etc to utilize the high temperature to kill the bacterial when bottling), that's why the plastic bottles (like Wahaha Nutrious Express) keep the shape it was when you use them to keep the boiled water; for the PET chips with the IPA concentration of 1.7%, the intenerated temperature is 70 degree centigrade approximately( this level are usually used for bottling the cabonate beverage like Coke Cola and Sprite or soda water) , thus this kind bottle could not be used to keep hot water, it would be distorted; and for another kind of PET chips with the IPA concentration of 2.6%or higher , the intenerated temperature is lower .