Foam Blow Molding

Alpla Technik produced bottles with a density as low as 0.68 g/cm in developmental work. Addition of pigment slightly increases the density. The foam cells cannot be seen with the naked eye, but are visible with a microscope. The cell diameter is between 50 and 100 microns in the bottle neck and base, and about 30 microns in the walls where the polymer is stretched. The surface layer is solid HDPE, with microbubbles in the core. Two-layer versions of the bottle have a smoother bottle surface but are somewhat heavier than monolayer bottles. 

The endothermic nucleating foaming agent uses hydrocerol agents reacting with baking soda and citric acid to release carbon dioxide with limited moisture. It is formulated in a PE-based master batch, and added at 1.5 to 2% levels. One grade 

The foam adds iridescence and brightness to the bottles because light reflects off the microbubbles, and therefore less pigment is required. Use of titanium dioxide can be eliminated because the foam structure produces a whitening effect in the HDPE. 

Foamed PET bottles were introduced in 1999, based on direct introduction of nitrogen into the mold producing microcellular foam. The resulting bottles had an appearance ranging from translucent to opaque, and weight reduction of up to 5% was achieved. The process was said to be applicable to PEN and PLA, as well as to PET [8] 

Foam blow molding is still in early stages of development, but does continue to be of interest for both packaging and nonpackaging uses [9]. 

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Radiation chemistry of PP has been extensively reviewed (162). Under suitable conditions, radiation treatment can lead to desirable branching reactions (163) with rheological characteristics favorable for thermoforming, foaming, blow molding, and extrusion coating. Resistance to radiation sterilization is an important requirement in some medical applications, and requires specialized formulation and stabilization packages. 

Foam = Structural foam molding T-Form = Thermoforming Blow - Blow molding... 

Important are behaviors associated and interrelated with plastic materials (thermoplastics, thermosets, elastomers, reinforced plastics, etc.) and fabricating processes (extrusion, injection molding, blow molding, forming, foaming, reaction injection molding, etc.). They are presented so that the technical or non-technical reader can readily understand the interrelationships. 

PBT-PC blends show increased melt strength allowing them to be easily processed by blow molding and profile extrusion. The PBT-PC blends have been extruded into sheet and thermoformed into parts. Enhanced melt strength allows PBT-PC blends to be foamed. Structural foam grades for injection molding (10-30% density reduction) are commercially available. 

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... 

Polyarylates are injection molded, using standard screw machines, as well as extruded, foam molded, and blow molded. Melt temperatures range from 600 to 680°F (316 to 360°C). Mold temperatures should he maintained between 200 and 300°F (93 and 149°C). 

The alloys can be processed into parts requiring hydrolytic and autoclave stability, such as desalinization filter frames and medical devices. Foamed products are used in cabinets for business machines, computers, and copiers. Automotive seat backs are made by blow molding and replacements for metal parts by injection molding. 

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