Extrusion Blow Molding Technology

As mentioned, a suitable technology consists in the fabrication of multilayer bottles. However, such multi-wall bottles have to be produced by the more complex and expensive co-extrusion blow molding technology. Using blends of PEN and HDPE can enhance the objected properties of HDPE bottles, using a simple one-step extrusion blow molding process. 

Co-extrusion blow molding represents a commercially viable technology that has hampered the wide commercial acceptance of the Selar technology. However, increasing needs to recycle production scrap and post-use waste might improve its market penetration. 

Technology to successfully produce multilayer injection blow molded bottles is much newer than that to produce multilayer extrusion blow molded bottles. Heinz Inc. s ketchup bottle was the first U.S. example (Fig. 12.22). The use of PET bottles made by coinjection blow molding has grown rapidly. As is the case for coextrusion blow molding, the key is production of the parison. Once the multilayer parison is produced, the remainder of the process is essentially the same as for single layer materials. Even stretch blow molding can be used. 

Related to extrusion blow molding is the extrusion-molded neck process (see Fig. 21). Still used by Owens-Illinois, this proprietary process can be traced to glass-blowing technology. In an unusual approach, the neck of the bottle is injection-molded and the bottle body is extrusion blow-molded. The two halves of... 

Extrusion blow molding is by far the most important method, with reference to both the size of the product and the amount of plastics processed. With today s technology, pieces with volumes from 1 cm to 10 m can be blown. This enormous size range does include packaging, storage, and transport containers, but it mainly... 

Biodegradable thermoplastics, like PHB and PLA, can be processed by conventional thermoplastic processing technologies, such as extrusion, injection molding, melt spinning, blowing film, and melt blown, for a wide range of application as enviromnentally friendly materials and for medical applications. 

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