Properties for Packaging

All polymers have a refinctive index that is characteristic of the polymer structure. The refractive index can be calculated by different theoretical methods based on the molecular weight and molecular volume of the monomer or constitutional unit, the density of the polymer and the chemical structure of the 

PET and cellophane films (PLA samples were obtained from Cargill Dow LLC) 

Physical properties of PLA polymers as well as other polymers depend on their 

Tensile yield stress (MPa) Percent elongation at yield Percent elongation at break Elastic modulus (GPa) 

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Thin-film XRD is important in many technological applications, because of its abilities to accurately determine strains and to uniquely identify the presence and composition of phases. In semiconduaor and optical materials applications, XRD is used to measure the strain state, orientation, and defects in epitaxial thin films, which affect the film s electronic and optical properties. For magnetic thin films, it is used to identify phases and to determine preferred orientations, since these can determine magnetic properties. In metallurgical applications, it is used to determine strains in surfiice layers and thin films, which influence their mechanical properties. For packaging materials, XRD can be used to investigate diffusion and phase formation at interfaces... 

In 1977 Idemitsu Petrochemicals announced that immiscible blends of LDPE with HOPE, with EPDM, or with an atactic polypropylene, aPP, are suitable for the production of soft, thin films, with improved properties for packaging (Sakane et al. 1979). Similar blends, LDPE with HOPE, PP, and EP block copolymer, were proposed by Shin-Kobe Electric Machinery (1984) for films with good modulus, tear strength, and no sagging behavior. Also, Showa Denko (1983) found that immiscible, but lightly compatibilized, blends of LDPE with either HOPE or MDPE are suitable for films with uniform thickness and anisotropic tensile strength. 

Emblem, A, Plastics properties for packaging materials. Packaging Technology, Woodhead Publishing. 2012, pp. 287-309. 

The PTFE micropowders are commonly used in plastics, inks, lubricants, and finishes such as lacquer. Lubricants containing micropowders are used for bearings, valve components, and other moving parts where sliding friction must be minimized or eliminated. Nonstick finishes that require good release properties, for example, in the food and packaging industry, commonly use PTFE micropowders. 

Certain bacterial species produce polymers of y-hydroxybutyric acid and other hydroxyalkanoic acids as storage polymers. These are biodegradable polymers with some desirable properties for manufacture of biodegradable packaging materials, and considerable effort is being devoted by ICI Ltd. and others to the development of bacterial fermentation processes to produce these polymers at a high molecular weight (66). 

Metallization. Integrated circuits require conductive layers to form electrical connections between contacts on a device, between devices on a chip, between metal layers on a chip, and between chips and higher levels of interconnections needed for packaging the chips. It is critical to the success of IC fabrication that the metallization be stable throughout the process sequence in order to maintain the correct physical and electrical properties of the circuit. It must also be possible to pattern the blanket deposition. 

Mylar For Packaging, Summary of Properties, Type 50 M-35, Form PBH, DuPont. 

Mylar For Packaging, Technical Information Service, Type 48 MM-20," Form E-71066, DuPont. Mylar For Packaging, Summary of Properties, Type 50 OL, Form PBH, DuPont. 

Poly(ethylene-i (9-vinyl alcohol) is made by saponification of ethylene—vinyl acetate copolymers. The properties of these materials depend on the amount of vinyl alcohol present in the copolymer. High vinyl alcohol content results in more hydrophilic materials possessing higher densities, stiffness, and moduh. They are used commercially as barrier resins for packaging. Important producers include Du Pont and EVALCA (74) (see Barrier polymers). 

Because of the excellent gas barrier properties, EVOH is of interest as a packaging material. However, because of its high water absorption it is usually used as an internal layer in a co-extruded film, sheet, bottle or tube. For example, the system HDPE-EVOH-EVA may be used as a barrier film for packaging cereals, and the system polystyrene-EVOH-polystyrene for packaging coffee and cream, whilst the system polystyrene-EVOH-polyethylene has the additional advantage of heat scalability. 

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