Loose-fill expanders

Polystyrene. There are two types of expandable polystyrene processes expandable polystyrene for molded articles and expandable polystyrene for loose-fill packing materials. 

Nearly all the expanded polystyrene that is not used for thermal insulation is used for packaging. Uses range from individually designed box interiors for packing delicate equipment such as cameras and electronic equipment, thermoformed egg-boxes to individual beads (which may be up to 5 cm long and about 1 cm in diameter) for use as a loose fill material. There is also some use of thin-wall containers for short-term packaging and conveying of hot food from... 

One of the first applications of biodegradable materials is based on the cooked, extruded, and expanded starch known from the food and chemical sectors (Fig. 14.23). Starch is cooked with water in the extruder and chemically modified as necessary or mixed with plasticizers, then expanded to a starch foam and dried. The extrudate is ground so that the functional properties thus created can be used in the food/chemicals sector. The foamed, cut, and dried extrudate is the end product for loose-fill packaging applications. The degree of expansion is a measure of the foam texture. It increases strongly with product temperature at the die, helped by a higher specific mechanical energy input. However, both measures increase the water-solubility of the product. 

Loose fill for packaging is produced by extruding and chopping polystyrene into various shapes, swelling with pentane, and steaming to expand them into peanuts. ... 

The Dow Chemical Company first entered the loose-fill packaging market in 1962 with a material that resembled spaghetti strands. Eventually the shape evolved to the S shape that characterized the product from the early 1970s to the present. Other competitors in the polystyrene foam loose-fill market include Flo-Pak, manufactured by Free-Flow Packaging, Inter-Pac, manufactured by Inter-Pac, WingPac and C-Pac, manufactured by Rapac, and Alta-Pak, manufactured by Storopack. In 1993, Dow sold the trademark rights to the S shape and Pelaspan-Pac to Storopack. The information about foamed polystyrene loose-fill that follows is an overview specific to materials that are formed in hard resin strands, cut to length, boxed and shipped to and later expanded for customer use at a convertor (expander) location. 

Polystyrene loose-fill packaging material used in US Federal Government applications must meet US Government Specification PPP-C-1683 (12/5/ 1988), Cushioning Material, Expanded Polystyrene Loose-Fill Bulk (for Packaging Application) . Compliance with eight properties is the basis for this... 

Expanded polystyrene loose-fill is used in many markets today. The most common are dunnage (used to fill up space in a shipping box), cushioning (where the resilient qualities of the polystyrene foam are used), and texturizer, where it is ground into smaller particles and used in making textured ceilings in commercial and residential buildings. 

Other styrenic polymer foams were developed in the mid-1950s through the early 1960s. Examples are molded expanded polystyrene foam (MEPS), extruded polystyrene foam sheet, and expanded polystyrene loose-fill packaging material. 

In addition to the ability to dispose of the used material by dissolving it, an interesting advantage of starch-based loose fill cushioning materials is they do not tend to build up electrostatic charges, so they do not cling the way packaging peanuts made of expanded polystyrene tend to do. 

Polystyrene foam (PS) holds much of the sheathing market. In masonry and brick walls, PS foams are mainly used because of their better moisture resistance. In cavity walls, loose fill PS is used, while exterior wall applications, which have no limitation on space, use low-cost expanded PS. 

Life cycle assessments were applied to analyse the degree of ecological damage caused by the production and disposal of loose fills made out of Mater-Bi pellets in comparison to those made of expanded polystyrene. 

The combination of starch with a water soluble polymer such as PVOH (or polyalkylene glycols) has been widely considered since 1970 [100]. Since the early 1990s these compositions have been mainly studied for starch-based loose-fill production as a substitute for expanded PS [101-107], using compositional water as expanding gas. In this kind of blends, not only natural starch but also modified ones such as hydroxy propylated high amylose starch can be used, especially to improve foam resilience and density [101-105]. 

In addition to recycling, there is considerable reuse of expanded polystyrene loose fill. The Plastic Loose Fill Council operates a toll-free Peanut Hotline to provide information to consumers about where to take EPS loosefill for reuse. This information is also... 

Polystyrene. There are five basic types of polystyrene foams produced in a wide range of densities and employed in a wide variety of applications (1) extruded polystyrene board (2) extruded polystyrene sheet (3) expanded bead molding (4) injection-molded structural foam and (5) expanded polystyrene loose-fill packaging. 

Polylactide has high potential in agricultural applications such as mulch films either in pure form or blended with other polymers such as thermoplastic starch. In addition, polylactide is used in compostable yard bags and dog poop bags. Lactic acid based hot-melt adhesives have also been developed (90). Foamed PLA could be used as structural protective foams, loose-fill packaging and insulation material as an alternative for expanded polystyrene (EPS). While packaging is currently the high volume application... 

Application of food extruders gives much better results in processing of starch-based materials than conventional plastic extruders due to the plant origin of the biopolymer. Most of the experimental works which apply extmsion-cooking for the production of starchy loose-fill foams started in the Department of Food Process Eng., Lublin University of Life Sciences in 2012. Their objective is to achieve commercially acceptable biodegradable products based on locally produced potato, corn- and wheat starch, which can replace popular expanded polystyrene loose-fill foam products. Results of the first phase of this study are presented in their work (Mitrus and Moscicki 2014). 

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