Forming solid-phase pressure

Solid phase pressure forming (SPPF) combines the use of pressure forming and plug-assist to form crystalline plastics at temperatures below their normal forming range, 5 to 8% below the crystalline melting temperature, in order to produce stiffer parts with less material. 

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Polypropylene can be extruded into sheets and thermoformed by solid-phase pressure forming into thin-walled containers. Due to its light weight and toughness, polypropylene and its copolymers are extensively used in automobile parts. 

Matched mold for solid phase pressure forming... 

Plug-assist solid phase pressure forming of disk into container... 

Keywords thermoforming, solid-phase pressure forming (SPPF), vacuum forming, pressure forming, processing window, viscoelasticity, residual stress, sagging, shrinkage, quality control. 

Formability. Materials with a broad softening range, such as PS and PC, can be thermoformed into deep-draw package shapes. Crystalline polymers, eg, HDPE and PP, are more difficult to thermoform, but solid-phase forming processes below the melting point are possible. Multilayer semirigid barrier containers are made by Shell s Solid Phase Pressure Forming Process and the patented Dow... 

In this chart, the critical area for therraoforming is at the 44 mol percent ethylene level. At 32 mol percent ethylene, EVOH crystallizes most rapidly at 161°C. This is the ideal temperature for solid-phase pressure forming (SPPF) of polypropylene. Polypropylene is one of the more popular structural materials for EVOH resin barrier containers. EVOH resins above 38 mol percent ethylene can be formed by SPPF methods. At levels belgw 38 mol percent ethylene, melt-phase forming at temperatures above 16l c is employed. EVAL resins at 38 - 44 mol percent ethylene are specially formulated for SPPF processing. 

SPPF Solid-phase pressure forming TETA Triethylene tetramine... 

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