Polyethylene packaging material

Polyethylene shrink film wrapping of cormgated ftberboard trays is in common use outside of the United States. Equipment erects the trays, fills the trays with primary packages such as cans or jars, wraps the grouping in shrink film, and heat shrinks the combination. Shrink film wrapping keeps primary and secondary packaging materials clean and dry. 

A small quantity of flexible packaging material, usually oriented polypropylene, shrink polypropylene, or polyethylene, is used to overwrap paperboard cartons. The film is wrapped around the carton and sealed by heating. Products such as boxed chocolates, candies, and cookies are overwrapped, sometimes by a printed film. 

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. 

Reclaimed rubber can be used in non-vulcanizing general-purpose NR adhesives. It can be used for insulation, packaging materials, and bonding of polyethylene, canvas, metals and wood. 

Polyethylene films as packaging material "plastic" squeeze bottles are molded from high-density polyethylene. 

In the early 1990s interest developed in the packaging material polyethylene naphthalate (PEN), a close cousin of PET. PEN has thermal stability 20°C higher than PET. Kodak had samples of the material sifting in its labs from the makers Teijin in Japan, as early as the beginning of the 1970s. Teijin is still the premier producer of PEN film and plastic today, and is involved with DuPont on the film manufacturing side. 

Polyethylene, because of its inertness and physical properties, is nearly ideal as a packaging material for food products. It is inert to most chemicals and, except for overheating (which can oxidize it) or irradiation (which can cross link the molecules), the chemical composition of polyethylene is difficult to change. There is one important property which it does lack—permeation resistance. 

Mustard. Mustard has been packaged in PVDC-coated cellophane/ polyethylene pouch material which was recognized to have a 3-6 month shelf life. In this case, the moisture loss rate was diminished by using the PVDC-coated cellophane. The main drawback of this package was the moisture loss, since the flavor was not markedly changed by the oxygen traces allowed by the PVDC cellophane coating. 

Packaging materials which have a smooth, impervious surface, free fi cm crevices or interstices, such as cellulose acetate, polyethylene, polypropylene, poly vinylchloride, and metal foils and laminates, all have a low surface microbial count. Cardboard and paperboard, unless treated, carry mould spores of Cladosporium spp., Aspergillus spp. md Penicillium spp. and bacteria such 2 Bacillus spp. sn.dMicrococcus spp. 

Because polyethylene terephthalate crystallizes slowly, it can readily be produced in its amorphous state. This is especially true when it is used in packaging materials, such as thin films and carbonated drink bottles. The final products exhibit high clarity and directionally balanced properties because they lack crystalline regions. 

With the exception of ethylene vinyl acetate added in the 1980 s, the list of materials and polymers approved as packaging for food irradiated products has remained static for decades. This article supplies details of the approved list, which includes such polymers as polyethylene terephthalate and polyvinyl chloride. The article provides an update on the latest proactive move to expand the list of packaging materials and polymers approved for the irradiation of foods. The expanded list would include ethylene vinyl alcohol, PVC film, ionomers, nylon 66, 6/12 and copolyesters among others. 

International Life Sciences Institute (2000). Report on Packaging Materials 1. Polyethylene terephthalate (PET) for food packaging applications. ILSI Europe Packaging Material Task Force, Brussels. 

Uses. As an antioxidant in the rubber and plastics industry as a stabilizer in polyethylene and polyolefin packaging materials for foodstuffs... 

Harden s (27) market survey of the growth of polyolefin foams production and sales shows that 114 x 10 kg of PE was used to make PE foam in 2001. The growth rate for the next 6 years was predicted as 5-6% per year, due to recovery in the US economy and to penetration of the automotive sector. In North America, 50% of the demand was for uncrosslinked foam, 24% for crosslinked PE foams, 15% for EPP, 6% for PP foams, 3% for EVA foams and 2% for polyethylene bead (EPE) foam. As protective packaging is the largest PE foam use sector, PE foam competes with a number of other packaging materials. Substitution of bead foam products (EPP, EPE, ARCEL copolymer) by extruded non-crosslinked PE foams, produced by the metallocene process was expected on the grounds of reduced costs. Compared with EPS foams the polyolefin foams have a lower yield stress for a given density. Compared with PU foams, the upper use temperature of polyolefin foams tends to be lower. Eor both these reasons, these foams are likely to coexist. 

Subramaniam, 1988]. Hydrochlorination, usually carried out at about 10°C, proceeds by electrophilic addition to give the Markownikoff product with chlorine on the tertiary carbon (Eq. 9-33) [Golub and Heller, 1964 Tran and Prud homme, 1977]. Some cyclization of the intermediate carbocation (XXVI) also takes place (Sec. 9-7). The product, referred to as rubber hydrochloride, has low permeability to water vapor and is resistant to many aqueous solutions (hut not bases or oxidizing acids). Applications include packaging film laminates with metal foils, paper, and cellulose films, although it has been largely replaced by cheaper packaging materials such as polyethylene. 

Polyethylene. The most straightforward process for the production of polymers from ethylene is that of the direct polymerization of the olefin. The polymerization process usually requires pressures and temperatures of 15,000 to 30,000 pounds per square inch and 200° to 300° C., and may be effected in either gas or liquid phase reactions (9). The polymer of molecular weight above 20,000 is the white, translucent plastic, polyethylene, widely used in electrical insulation, packaging material for foods, cosmetics and pharmaceuticals, liners for paper bags, etc. Articles molded from polyethylene are semirigid or rigid, depending on their thickness, but in thin films the material has excellent flexibility, even at relatively low temperatures. 

The packaging material is a laminate made from layers of paper, plastic (polyethylene) and aluminium foil. The particular composition for a given product is chosen according to its specific requirements. This affords the best protection to each product and keeps it in peak condition until consumed. Polyethylene is laminated to the board to make it impermeable, and an aluminium foil (of 10 p.m or less) is added to increase the barrier properties against external hazards such as sunlight and atmospheric oxygen, which would cause deterioration of product quality. 

The new packaging system developed by Tetra Pak is known as the Tetra Brik , and is generally available in 1-1, 200-ml, and 250-ml sizes. The system is considered to be an alternative to metal and glass containers. The packaging material comes in roll stock form and is a 6-or 7-layer laminate. Polyethylene and aluminum foil offer the major barrier properties to the package. 

Formaldehyde, along with other short-chain aldehydes such as acetaldehyde, is a low molecular weight, volatile, reactive contaminant that can be present at low levels from a variety of sources (e.g., excipients such as polyethylene oxide, polyethylene glycol (64,65), or from carbohydrate degradation (66), solvent contamination (51), packaging materials (52), etc.). Formaldehyde is known to react with amines (Fig. 33) to form a reactive N-hydroxymethyl compound (a hemiaminal) that can further react with other nucleophiles. Reaction of formaldehyde with amino acids (67) can cause... 

The manufacture of packaging materials is often conducted under conditions of high temperatures. A burnt polyethylene odor has been experienced in the paper/foil/ polyethylene laminate field. These conditions can easily induce thermal degradation with the formation of volatile compounds in packaging materials (8-131. 

Papachristou, C., Badeka, A., Chouliara, I., Kondyli, E., Kourtis, L., and Kontominas, M. G. (2006a). Evaluation of polyethylene terephthalate as a packaging material for premium quality whole pasteurized milk in Greece. Part II. Storage under fluorescent light. Eur. Food Res. Technol. 224, 237-247. 

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