Study Of Poly(Ethylene Terephthalate)(PET) For Carbonated Soft Drink Bottles On Structure And Properties

PET (Polyethylene terephthalate) for its excellent properties is widespread used in the package of carbonated soft drinks (CSDs).In the middle of the 1980s,the carbonated soft drink bottles which are made of round bottom PET bottles and PE bottom stand, were changed into petaloid bases PET bottles, which also bring the problems that the petaloid bases are easy to have stress cracks. At present there are few researches about the CSDs bottles resisting stress cracks in domestic, most of which just study it from process .But the studies are seldom from the quality of the bottle chips , a lot of companies still can't solve the stress crack problems caused by the quality of bottle chips.In this paper we used crystallization rate detector, DSC, polarizing microscope to study the influences of crystallization on PET chips for CSDs bottles. We processed the chips into bottles and studied the effects of crystallite distribution of CSD PET bottles on resistance stress crack by polarizing microscope .We firstly used parallel plate rheometer to study PET bottle chips to analysis the influences of rheology on the properties of PET CSDs bottles. The results showed:1.The content of diethylene glycol(DEG) and isophthalic acid ,and the increase of molecular weight would decrease the rate of crystallization. The chips with slow rate of crystallization easily cooled to amorphous, which could stretch fully during the stretching process of bottles.2.With the preservation time going on, the resistance time of stress crack of CSDs bottles decreased. PET bottles with uneven stress distribution were easy to have stress crack.3.Dynamic and steady shear rheological measurements were carried out to examine the rheological properties of PET CSDs bottle resin, and the rheology of PET can be used to estimate the quality of PET bottle .Dynamic rheology showed PET-D2 with low molecular weight distribution were easy to process.