Soft-blowing method

Figure 5 shows an outline of the experimental appratus. The fused lead was placed in a reaction tube made of quartz. The reaction was studied by the bubbling method in which H2S was bubbled into the fused lead and by a soft blowing method in which H2S was blown onto the surface of the lead. The H2S gas stored in vessel No. 1 was circulated by pump No. 2. Since the lead content was in excess of the H2S in order to maintain the liquid state, the reaction behavior was examined in this experiment until the gas reached the equilibrium composition. 

Extrusion stretch blow molding begins with an extrusion blow molded preform injection stretch blow molding begins with an injection molded preform. Injection stretch blow molding is the method of choice for most PET bottles, including all soft drink bottles. It is also used for PEN bottles and some PP bottles. Extrusion stretch blow molding is used for some PVC bottles. 

In stretch blow molding, a heated pre-formed melt is positioned in the blow mold (Figure 1.5). A center rod extends which stretches the preform with axial orientation. Blown air then expands the preform in the mold, fcwming a bottle with radial orientation. The stretch process takes advantage of the crystallization behavior of the resin and requires the pre-form to be temperature conditioned and then rapidly stretched and cooled. PET soft drink bottles are formed using the stretch method. PET bottles are also formed using extrusion blow molding. 

If the object is only to investigate the depth of overburden, geophysical methods can advantageously be applied. In a case where the overburden is of a loose or fairly soft character, seismic measurements, more particularly by means of the hammer blow technique, are very suitable, as they can be performed quickly and inexpensively. However, this technique does require a relatively level surface of the limestone. If the surface is very irregular, e.g., as a result of underground water percolation, this method of investigation cannot be used. The application of the hammer blow technique in conjunction with penetration tests is especially to be recommended. 

Injection blow moulding is most commonly employed for the production of transparent soft drinks containers. However, extrusion blow moulding is the method most commonly employed for mouldings such as shampoo and detergent containers, plastic drums and milk bottles. An extrusion blow moulding machine is shown in Figure 6.11. 

Polyethylene terephthalate (PET) bottles were commercially introduced to the market place for the first time in 1976, by Pepsi Cola. The bottles were supplied by Amoco from their Seymour, IN plant, blown on Cincinnati Milacron machines, from preforms molded in molds supplied by Broadway Mold in Dayton, OH. The PET bottle introduction coincided with the FDA-forced withdrawal of the Monsanto supplied Coca Cola ANS bottles, making it the only plastic carbonated soft drink (CSD) bottle on the market. Fig. 33.3 shows a Continental Can Company (CCC) bottle produced in the company s first PET bottle blow molding plant in 1977. A second important milestone was the introduction in Japan by Yo-shino in 1982 and in the United States by Monsanto in 1985, of bottles suitable for hot filling, a typical filling method for perishable beverages like juices. The Yoshino and the Monsanto bottles are shown in Eig. 33.4 and Fig. 33.5, respectively. 

Impact strength is usually only determined for plastics and hard elastomer compounds (i.e., those in the D durometer hardness range), where the impact resistance of the material in actual service is important. Soft elastomer compounds will bend, not break, on impact unless they have been cooled below their brittleness temperature. Several types of impact testers and test methods are available. Basically, they all measure the energy required to break a test specimen in a single sharp blow, and can be performed over a temperature range from -70 to +120°C (-94 to +248°F). The most widely used tests are Izod Impact and Charpy Impact both procedures are given in ASTM D-256. 

Pellethane thermoplastic polyurethane elastomers range from hard to soft and can be fabricated by a variety of methods, from injection molding to extrusion and blow molding. These elastomers offer a combination of properties rarely seen in an engineering thermoplastic. Table 16 gives descriptions and applications of Pellethane TPE-U products. 

---