Poly film blowing

Miinstedt, H., T. Steffi, and A. Malmberg. 2005. Correlation between rheological behaviour in uniaxial elongation and film blowing properties of various poly-... 

Novamont, a subsidiary of the Italian company Montedison, marketed Mater-Bi biodegradable film for composting and waste disposal. A typical resin contains 60% starch along with other materials. Mater-Bi resins containing starch and poly- -caprolactone can be handled on conventional film blowing and sealing equipment for LDPE, with minor modifications. One U.S. manufacturer of trash bags made with this material is Biocorp USA, which sells them as... 

Starch can also be destructured in the presence of more hydrophobic polymers such as aliphatic polyesters (141). It is known that aliphatic polyesters with low melting points are difficult to process by conventional techniques for thermoplastic materials, such as film blowing and blow molding. With reference particularly to poly(e-caprolactone) and its copolymers, films produced thereby are tacky as extruded, and rigid, and have low melt strength over 130°C moreover, because of the slow crystallization rate of such polymers, the crystallization process proceeds for a long time after production of the finished articles with an imdesirable change of properties with time. 

Union Carbide, Daicel and Interox are the three producers of poly-s-caprolactone world wide. High molecular weight poly-s-caprolactone may be processed by a variety of techniques, including film blowing and slot casting. Main application in the field of biodegradable plastics is in combination with thermoplastic starch in films, sheets and injection molded parts. 

In this section, examples of films made from poly-vinylidene fluoride (PVDF) are discussed. Although most of the polyvinylidene fluoride film is in the form of coating on metal substrates, stand-alone PVDF films and sheets are produced by extrusion and film blow-ing.P2][23] Bientjs of PVDF and a number of other polymers such as polymethylmethacrylate are miscible. Films made from these blends have excellent piezoelectric properties that are described further in Ch. 13. 

PCL is a semi-crystaUine polymer with a degree of crystallinity of 50%, a low Tg (-60 °C) and a melting point of 60 °C. Injection-molded samples of PCL exhibited a modulus of 400 MPa and a yield stress of 15 MPa. Moreover, the material can be processed by injection molding, film blowing and extrusion. The rate of crystallization of PCL is slower than that of conventional polymers, while poly(ether-ester)s are more flexible due to the presence of ether linkages. Although PCL and poly(DXO) resemble each other in their chemical structure, PCL is semicrystaUine whereas poly(DXO) is an amorphous polymer with a Tg of approximately -37 °C [37]. 

The film tube is collapsed within a V-shaped frame of rollers and is nipped at the end of the frame to trap the air within the bubble. The nip roUs also draw the film away from the die. The draw rate is controlled to balance the physical properties with the transverse properties achieved by the blow draw ratio. The tube may be wound as such or may be sHt and wound as a single-film layer onto one or more roUs. The tube may also be direcdy processed into bags. The blown film method is used principally to produce polyethylene film. It has occasionally been used for polypropylene, poly(ethylene terephthalate), vinyls, nylon, and other polymers. 

PEN film for audio- and videotape and various electronic appHcations and blow molded PEN containers for hot-fill appHcations are already being marketed in Japan. NDA is unlikely to ever become as inexpensive as terephthaUc acid but novel NDA-based polyesters will become available if a market need exists. One example could be the experimental polyester PBN (Celanese Corp.) this is the NDA analogue of PBT, poly(l,4-butylene naphthalene-2,6-dicarboxylate) [28779-82-0]. It has a high rate of crystallization, faster even than that of PBT, and its combination of physical properties is weU-suited for injection molding. 

Focusing collectors are usually cast acrylic Fresnel lenses, or mirrors of aluminized polyester film in frames of aluminum. These reflectors are either enclosed in a bubble of poly(vinyl fluoride) film, or under polycarbonate glazing, which may be covered with a fluorocarbon film to reduce the reflectivity. The absorbers for active systems are copper or aluminum since the temperatures are too high (325—370°C) for plastics. The frames, however, can be molded ABS, high density polyethylene or polyurethane, either solid or structural foam. Polybutylene or chlorinated PVC can be used for piping hot water, and tanks can be made of either reinforced polyester or blow- or rotational-molded, high density polyethylene (12—15). 

Polyolefins can be coated with other materials, such as poly(vinylidene chloride), in order to reduce the permeability by gases of the walls of blow mouldings or film (thus extending the shelf-lives of products contained in them) however, barrier coatings of this nature cannot be applied satisfactorily to the untreated surfaces. 

Mar lex . [Phillips Phillips Petrol. Chem. SA/NV] Pdyethytene or poly-prt lene resins for inj., blow, orrota-ttoial nodditig ( therimtorming appliance parts, chmnical equipment industrial parts, containors, toys, hmise-wares, chemical tanks, monofilament film applies. 

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