The beverage industry is considered as one of the most competitive industry among all consumables. And, their packaging is an important element to attract consumers. Attractive shapes, colorful bottles, fascinating punch lines; all are part of the promotional strategy. Along with that, the producer has to make sure that when it is reaching to its consumer; hygiene, freshness, quality and taste; everything is as per their standards. In aerated drinks, it is very important that bottles are maintaining their fizz. On the other hand, packaged juices and tetra packs of milk do not get puffed. There is no place for consignment which is damaged or puffed. Even, PET bottles of aerated drinks sometimes get crushed due to over-weight stacking.
All these after effects are due to defect in preforms. Using some testing instruments like Glass & Plastic Polariscope -Strain Viewer, many defects can be identified in the preforms, which saves a huge time of blow molding and stretch molding.
What are some common defects that need to be addressed?
Crystallization
PET is a form of a polymer which has regularity in geometric and chemical structure. The ability to form regular structures is called crystallization. Higher the crystallization better is the quality. Although, attaining 100% crystallization is very difficult. Very high level of crystallization can be achieved by heating the polymers at glass transition temperature Polymers with high transition temperature have high tensile strength, toughness, stiffness and resistance to solvents.
Coming back to packaging, if the PET preforms have uneven crystallization properties, it will produce defective bottles. Usually, such defects can mostly be observed near the neck of the bottle. Uneven wall thickness, high flexibility, etc. can lead to the production of sub-standard bottles which are prone to crushes and breakage.
Strain distribution
Strain distribution is an important factor to calculate in PET bottles; as it determines the uniformity in the transparency of the bottle and strain bearing capacity. The life and strength of PET bottles largely depend on the strain distribution. Glass & Plastic Polariscope -Strain Viewer can be used to determine the load distribution before the blow molding or stretch molding.
Bad transparency
Transparency of bottle is an important factor in maintaining the quality of beverage inside the bottle. The higher the level of opaqueness of bottle, the more it will have the tendency to block the rays of the light spectrum, especially UV rays. This is becoming an important aspect in managing the quality of bottle because many of the beverages are sensitive to UV rays, especially those, that are rich in Vitamins, and coloring agents. Excessive UV penetration may degrade the taste of beverage and may hamper the reputation of the brand.
