What about the properties of stretch blow moulding products?
After stretching, the material's impact strength, low temperature strength, transparency, surface roughness, stiffness and resistance have been greatly improved.Especially the improvement of impact strength, expanded the application range of the packaging container of the blow molding products;In addition, it can also save raw materials, reduce the gross weight of products, and improve the competitiveness of products.
The transparency of hollow products is very important.For amorphous thermoplastics (e.g., polyacrylonitrile, polyvinyl chloride (PVC) and polystyrene), part of crystallization of plastic (such as polypropylene, polyethylene terephthalate), although itself has a certain transparency, but after stretching, the transparency has more obvious increase, surface gloss and further improvement can be obtained.After stretching, the elastic modulus of the material is greatly increased, which is beneficial to the improvement of internal pressure strength and axial stiffness required for packaging materials.
From the point of view of packaging, the most important performance is the permeability to gas.The permeability of some crystalline plastics, such as water vapor, oxygen, carbon dioxide, and aroma, decreases markedly after stretching, but there are differences among the materials.The permeability of polypropylene to water vapor is relatively low. After being stretched, the permeability decreases slightly, but it still cannot be compared with PVC, polyvinylidene chloride and ethylene terephthalate.