Proprietary research from PET blow molding consultant PTI shows that PET bottle performance issues may have their root cause in how long preforms are stored and in what environment.”Our plant-support personnel were frequently being asked what storage duration was acceptable for preforms and what problems can present themselves during longer storage periods,”explains Sumit Mikherjee,chief technology officer of PTI.”With amost 40 years of experience in this area,we knew that the longer the preform is stored,the greater the impact on performance-particularly if that preform was stored in a high-humidity environment.”PTI studied 2L and 20-oz preforms that were more than a year old.These preforms were dried under vacuum to get them back to a condition similar to when they were first molded.According to PTI,”Preforms stored three,six or 12 months will each process differently.The older the preform,the more difficult it will be to process so that the container meets performance criteria.The time of year the preforms were injection molded,along with the environmental conditions in which they are kept,will also impact performance.”
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