Manufacture of PET Preforms

Preforms must be designed properly for the container they are expected to make. This means that they come in many different shapes, as shown in Fig. 12.16. The one dimension that controls the cycle time the most is the wall thickness of the 

Another compromise is made when blowing multiple bottle sizes from the same preform. This may not be optimum from the perspective of polymer utilization, but it may save lots of money on inventories and mold costs. As shown in Section 12.3.2, one can design the preform for optimum wall thickness distribution by using finite element analysis. Sometimes polymer is less expensive than molds. 

Thermal degradation can also cause IV loss, color generation, and acetaldehyde production. For colorless bottles, any color is bad. AA has a fruity flavor that can affect product quality because it is very potent at small concentrations. As shown in Fig. 12.18, as temperature goes up, haze decreases and acetaldehyde concentration increases. 

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