Thermoforming window

There are plastics that are transparent and translucent in the unpiginented state. They have a range of optical properties that make them interesting for a wide spectrum of optical applications that extends from windows to lens systems to sophisticated applications involving action via polarized light. Used for over a half century are aircraft canopies (thermoformed) and windows in many different structures. 

OPS is commercially available in 0.13-0.76 mm gauge. The tenter frame process for manufacturing OPS is the most common process used today. A typical tenter frame process is shown in Figure 11.1. Tentered OPS is distinguished from polystyrene blown films (which are also biaxially oriented) in that the tenter frame process can produce heavier gauge films than the blown-film process. Blown films (0.025-0.13 mm) are used primarily in window envelopes, lamination, and printed applications tentered OPS is typically used in thermoformed trays, lids, and containers for rigid food packaging applications. 

Owing to the presence of PA, the PA/ABS blends (Triax 1000) have narrow processing window. Forming temperature range from 235 to 250°C. Prior to thermoforming, the stored sheets must be dried at 85°C for 8 hours. 

For interior applications in public transport, another blend has gained widespread use — acrylic/PVC parts made by thermoforming. Its extruded sheets see use as benches, seat backs, armrests and window reveals for subways, railroad cars, buses, monorails and trolleys. Key properties that this alloy possesses include scratch and scuff resistance, and the ability to be cleaned easily using harsh detergents. 

PMMA is a transparent thermoplastic with high glass-transition temperature (7g 105 °C), commonly used as glass replacement in windows and in colored thermoformed... 

PC thermoforms well, and has major uses in medical packaging, where it can be sterilized by autoclaving or by electron beam or gamma radiation. Its toughness is PC s most impressive property. For instance, PC is the material of choice for school windows and sports equipment. Being tough and clear make PC a material well... 

Styrene butadiene copolymers come in a wide variety of types, with a similar wide variety of properties. As discussed in Section 4.6, HIPS (High Impact PS), is partially a graft copolymer and partially a physical blend of polystyrene and polybutadiene. HIPS, which is opaque, typically contains 2 to 15 weight % polybutadiene. In addition to significantly decreased brittleness, it has a broad processing window and is easy to thermoform, either as sheet or as extruded foam. 

Film Processing Methods Blisterpacks are thermoformed from coextruded and laminated films. Ticona Topas 8007 COC has a wide processing window and can be used on standard blister lines with... 

Generally all thermoplastic polymers can be processed by thermoforming, but there are significant differences regarding process windows. Amorphous polymers show a wider softening temperature range than semi-crystalline polymers, which results in a wider process window and a more stable process [7]. For this reason only few semi-crystalline polymers are used in thermoforming, for example PP, PE, C-PET and polyester. The most commonly used amorphous polymers are PVC, PS, ABS, SAN, PMMA, PC and A-PET. 

Unplasticized polyvinyl chloride Tubes, window frames, siding, rain gutters, bottles, thermoformed packaging, etc. 

There are many applications for opaque materials based on thermoforming. These include signage, window covers, seat components including seat backs, and semi-structural panels. Film products include safety labels commonly seen on seat backs. 

Yoghurt pots provide an illustration in everyday life of this kind of preparation. They are produced from thin polystyrene sheets, heated then stamped out and cooled. Curved caravan windows are made in this way from poly(methyl methacrylate) plates. Large objects such as chairs, beds and baths are made by thermoforming polystyrene or poly(methyl methacrylate) plates. 

Window frames and doors PVC, foamed PVC (wood substitute), ABS (coextruded with vinyl modified ASA or polyolefins modified styrene acrylonitrile copolymer (SAN) -glass-fibre reinforced plastic (GFRP), composite based, ABS (thermoformed panels for high quality doors and window profiles)... 

PP s semicrystalline nature imparts to it an excellent combination of physical, thermal and chemical properties which makes it a premium material in packaging applications. Its commercial exploitation in this sector has, however, been impeded by several material-related properties which make it difficult to thermoform. The main problems are (1) low melt strength leading to sagging of the sheet during heating and which in turn results in parts with poor material distribution, and (2) a narrow temperature processing window within which the sheet may be formed. 

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

The Second World War accelerated interest in thermoforming, with the demand for cast poly(methyl methacrylate) fighter/bomber windows, grm closure and windscreens (5). 

---