Blow Molding and Bottles

Molding includes bottle blow molding, and the continued move toward PET for use in soft drink and water bottles depresses growth slightly, although the trend remains positive. 

Polyvinyl chloride (PVC) is one of the most widely used thermoplastics. It can be extruded into sheets and film and blow molded into bottles. It is used in many common items such as garden hoses, shower curtains, irrigation pipes, and paint formulations. 

Energy and bottle An interesting historical (1950s) example is the small injection blow molded whiskey bottles that were substituted for glass blown bottles in commercial aircraft continues to be used in all worldwide flying aircraft. At that time, just in USA, over 500 x 1012 Btu or the amount of energy equivalent to over 80 x 106 barrels of oil was reduced. 

A surprisingly low concentration of water can reduce the viscosity such that reclaimed PET cannot be used for the blow molding of bottles with acceptable physical properties. The established solution to the moisture problem is to dry the recycled PET in special dryers prior to use. However, the drying process is both time and energy intensive. Paper labels can cause problems in PET recycling if they decompose during washing and removal. The paper fibers formed can produce cellulose fibers that are difficult to remove from the reprocessed PET.1... 

Low-density polyethylene (LDPE) film for food packaging, etc. High-density polyethylene (HDPE) blow molded into bottles and containers... 

Polyethylene terephthalate is most often extruded into films or fibers, or blow molded into bottles. Polybutylene terephthalate is primarily found in injection molded parts. Such parts are highly crystalline, which makes them opaque. Polybutylene terephthalate is often modified with glass fibers or impact modifiers. Table 24.1 contains applications by processing method and resin. 

PET is by far the largest-volume thermoplastic polyester in production today. It was first synthesized by J. R. Winfield in the UK in the 1940s and its first commercial application was as a textile fiber. PET was also produced as a film for packaging and blow molded into bottles for beverages long before it had any... 

Typical HDPE—blow-molded products bottles, cans, trays, drums, tanks, and pails injection-molded products housewares, toys, food containers, cases, pails, and crates films, pipes, bags, conduit, wire and cable coating, foam, insulation for coaxial and communication cables... 

G Injection, blow molding, and extrusion and other conventional methods Autoclavable laboratory ware and bottles... 

Figure 8-4. Schematic of three-station blow-molding machine (McCrum, Buckley, and Bucknall 1997, courtesy of Oxford University Press). Station 1 injection molding of parison station 2 blow molding of bottle station 3 ejection of bottle.

PET s broad range of properties make them ideal replacements in certain applications for such metals as die-cast aluminum or zinc also in thermoset switches, relays, sensors, etc. Applications include packaging (particularly stretched injection blow molded beverage bottles and film), appliances, electrical/electronics, etc. PET finds applications in such diverse end uses as fibers for clothing, films, botdes, food containers, and engineering plastics for precision molded parts.118-120 A wide range of applications is possible because of the excellent balance of properties PET possesses and because the degree of crystallinity and the level of orientation in the finished product can be controlled. 

SBC can be processed on most conventional blow molding and injection blow molding equipment designed for many other types of polymers with little or no equipment modifications. This includes continuous, accumulator head, or reciprocating screw extrusion blow molding equipment. Bottles made from SBC have been used widely for applications such as honey bears. The SBC will withstand the moderate hot fill temperatures required for this application. 

In contrast with the applications for LDPE, about two-thirds of high-density polyethylene is used in molding applications, split about 40% into blow molding of bottles and containers, and 25% into injection-molded products. A further 10% of the total HOPE resin output is consumed in each of the pipe and electrical conduit fabrication areas, and for film and sheet products. 

Also, the proportion of fibers in the skin (or shell) and those in the core depends on the rates of fiow." Low injection rates and low temperatures causes an expansion of the shell (skin) region These relationships also affect the orientation of polymer chains in filled and unfilled polymers during proc-essing Orientation of fiber in blow molding of bottles filled with fibers caused anisotropy of properties. Tensile strength was increased in the machine direction. At the same time, talc filled bottles had more uniform tensile properties than unfilled bottles. ... 

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