Polyvinylidene chloride plastic PVDC

MIR techniques have simplified obtaining infrared spectra of many materials important in packaging. These include rubber, plastics, laminations, and components of these materials that find use in pumps, sample packages, and devices. The combination of MIR and computerized pattern recognition techniques can be used for differentiating and classification of flexible packaging polymers such as polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), acrylonitrile (Barex), and CTFE (Aclar) [22]. 

BMs commonly include from two to seven layers, although more are also used. The construction usually includes one or more barrier layers. These are plastics with a particular resistance to the transmission of water vapor or gases such as oxygen or carbon dioxide. Examples are ethylene vinyl alcohol (EVOH), nylons, and polyvinylidene chloride (PVDC). Their presence greatly enhances the performance of the BM as a package for foodstuffs, beverages, and other critical products. The barrier materials are all deficient in some respect such as price, mechanical strength, and moisture resistance. Thus not used as a material of sole construction for BM. Their use is in thin layers shielded by other more robust and economical body plastics. 

The use of other plastics tends to be related to specialised needs and whether their advantages justify the additional cost, e.g. Aclar (trade name) may cost twenty times more than PET but is the nearest approach to an inert plastic and is approximately ten times less permeable than Saran (PVdC—polyvinylidene chloride) which is widely used as a film coating. However foil, even when thin (0.006 mm and above) remains the best barrier material, with newer techniques of film metallisation, especially where two contact layers are used, coming a close second best. 

Polyvinylchloride (PVC) is commercially the most signihcant member of the family of vinyl resins. The other important members of this group are chlorinated-PVC (CPVC) and polyvinylidene chloride (PVDC). PVC is one of the most widely used, commodity type thermoplastics with an annual consumption of over 5 Mton/y in the USA. The excellent versatility of PVC is attributed to its blending capability with a variety of plasticizers, additives and fillers to yield products ranging from very flexible to very rigid types. In addition, PVC has a low cost advantage and a reasonably good balance of properties, which... 

General Description Polyvinylidene Chloride (PVDC) resin is a copolymer of vinylidene chloride (VDC) with vinyl chloride or other monomers Dow Plastics vinyl chloride and vinylidene chloride, Saran, is usually supplied as a white, free-flowing powder. Dow Saran polymers are known worldwide for their gas-moisture, and chemical-barrier properties, and for their ignition-resistant properties. 

Polyvinylidene chloride (PVDC) is typically used as a vapor barrier in food packaging. In these applications, evaporation rates are usually 10-15 kg/h/m with air velocities of 20-40 m/s when utilizing paper substrates and 20-40 m/s when using plastic films. Dryer construction is usually of stainless steel because of the high corrosivity of the coatings and airstream. 

At the present time, there is considerable concern about the effects of two categories of pollutants which overlap considerably, but are not identical. One focus is emissions of organic chemicals containing chlorine. The other is on emissions of chemicals which are mimics or antagonists of natural hormones, particularly estrogen. Within the plastics industry, polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) are the polymers most affected on both fronts. Many of the suspected hormone-like chemicals are chlorinated, and some of those which are not chlorinated are used as plasticizers in PVC. The vinyl industry has been attacked by Greenpeace and some other... 

DBS is an excellent low teoqperature plasticizer for synthetic r ibbers and vinyl chloride polyaers and copolyaers. It is also an effective process plasticizinci aid for polyvinylidene chloride (PVdC) copolyaers. 

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