Page 50 - Handbook of Plastics Technologies
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INTRODUCTION TO POLYMERS AND PLASTICS


                             1.36                        CHAPTER 1






















                                FIGURE 1.35 Billow vacuum process. 72

























                             FIGURE 1.36 Vacuum snap-back process. 71


                             that can be successfully thermoformed include PE and nucleated PETP. Nylons typically
                             do not have sufficient melt strength to be thermoformed.  Table 1.9 shows processing
                             temperatures for thermoforming a number of thermoplastics.


                             1.6.4  Blow Molding
                             Blow molding is a technique for forming nearly hollow articles and is very commonly
                             practiced in the formation of PET soft-drink bottles. It is also used to make air ducts, surf-
                                                                     38
                             boards, suitcase halves, and automobile gasoline tanks.  Blow molding involves taking a
                             parison (a tubular profile) and expanding it against the walls of a mold by inserting pres-





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