Poly blown film extrusion

Thermoplasticity. High molecular weight poly(ethylene oxide) can be molded, extruded, or calendered by means of conventional thermoplastic processing equipment (13). Films of poly (ethylene oxide) can be produced by the blown-film extrusion process and, in addition to complete water solubility, have the typical physical properties shown in Table 3. Films of poly(ethylene oxide) tend to orient under stress, resulting in high strength in the draw direction. The physical properties, melting behavior, and crystallinity of drawn films have been studied by several researchers (14—17). 

Extrusion is a cost effective manufacturing process. Extrusion is popularly used in large scale production of food, plastics and composite materials. Most widely used thermoplastics are processed by extrusion method. Many biopolymers and their composite materials with petroleum-based polymers can also be extruded. These include pectin/starch/poly(vinyl alcohol) (Fishman et al. 2004), poly(lactic acid)/sugar beet pulp (Liu et al. 2005c), and starch/poly(hydroxyl ester ether) (Otey et al. 1980), etc. In this study, composite films of pectin, soybean flour protein and an edible synthetic hydrocolloid, poly(ethylene oxide), were extruded using a twin-screw extruder, palletized and then processed into films by compression molding process or blown film extrusion. The films were analyzed for mechanical and structural properties, as well as antimicrobial activity. 

Biaxial orientation effects are important in the manufacture of films and sheet. Biaxially stretched polypropylene, poly(ethyleneterephthalate) (e.g., Melinex) and poly(vinylidene chloride) (Saran) produced by flat-film extrusion and tentering are strong films of high clarity. In biaxial orientation, molecules are randomly oriented in two dimensions just as fibers would be in a random mat the orientation-induced crystallization produces structures which do not interfere with the light waves. With polyethylene, biaxial orientation often can be achieved in blown-film extrusion. 

Biodegradabihty in soil of the poly(butylene succinate adipate) (PBSA)-starch films prepared with starch contents of 5-30% by weight and processed by blown film extrusion was assessed [143]. The rate of biodegradation in soil, as measured by respirometry, increased significanly as the starch content was increased to 20% and then plateaued. 

Other Vinyl Resins. One of the most important uses of poly(vinylidene chloride), PVDC, is for packaging film. The PVDC resin used for this purpose is usually a copolymer of vinylidene chloride and vinyl chloride. The film is produced by casting or by blown film extrusion. Biaxially oriented film is clear, with good strength and low permeability to moisture and other gases. This makes it especially useful for food packaging. 

Poly(butylene succinate) can be molded on conventional thermoplastic processing equipment, including blown film, mono-filament extrusion, blow molding, and injection molding. PBS pellets should be dried to a water content of less than 0.1% to prevent hydrolysis (Xu and Guo... 

A breathable poly(urethane) membrane has been manufactured by using a multilayer film extrusion technique. In the course of this process, the membrane is blown as the inner layer of a three-layer film. The outer support layers are based on poly(ethylene). It was fotmd that the neat membrane surface was vmacceptably sticky. However, starch is a suitable antiblocking agent and better than... 

Poly (ether-6-amide) products are known to have an excellent processability in injection molding, extrusion (cast films, blown films, sheets, tubes, etc.), as well as in assembly processes like overmolding and co-extrusion. This behavior allows the design of thin and sophisticated-shaped materials associating lightweight and good mechanical properties. In order to achieve the best processing... 

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