What is EVOH barrier film?
EVOH Films Ethylene-vinyl alcohol copolymer or EVOH is a flexible, crystal clear, and glossy thermoplastic copolymer with excellent flex-crack resistance, and very high resistance to hydrocarbons, oils and organic solvents. In comparison with many other common films, EVOH has superior barrier properties.
Is EVOH a good water barrier?
When compared to other common films, EVOH is considered to have superior barrier properties. For this reason, EVOH is often used in a multilayer co-extruded film structure with materials such as HDPE, PP and PET, all of which have superior moisture barrier properties.
Is EVOH a polyolefin?
EVOH can easily be co-extruded with all types of polyolefins, polyamides and other materials using standard extrusion equipment. The scrap generated in polyolefin/EVOH coextrusion is commonly recycled as a regrind layer in sheet and bottle applications.
Is EVOH hygroscopic?
EVOH is hygroscopic material with barrier properties dependant on air moisture. Application: Widely applied to food packaging due to its low oxygen permeability. Used in multi-layer structures production and in fuel containers acting as barrier for hydrocarbons.
What is EVOH made of?
Ethylene vinyl alcohol (EVOH) is a formal copolymer of ethylene and vinyl alcohol. Because the latter monomer mainly exists as its tautomer acetaldehyde, the copolymer is prepared by polymerization of ethylene and vinyl acetate to give the ethylene vinyl acetate (EVA) copolymer followed by hydrolysis.
Why is EVOH material used in combination with other plastics in map?
However, EVOH is highly sensitive to humidity, which alters its resistance to O2 permeability [12]. Therefore, EVOH material is often combined by coextrusion with other polymeric materials, such as PP and PE, to increase barrier properties, as well as water-resistant polymers [13].
Is EVOH water soluble?
EVOH consists of hydrophobic ethylene and hydrophilic vinyl alcohol segments, has good solubility in DMSO. It has also been shown that EVOH is only soluble in solvent mixtures such as THF/methanol and DMSO/n-propanol(13).
What is EVOH made from?
Is EVOH crystalline?
Ethylene–vinyl alcohol (EVOH) is a copolymer of ethylene and vinyl alcohol. These materials are highly crystalline and are produced with various levels of ethylene content. Figure 10.4. The structure of EVOH copolymer.
Why is EVOH a good oxygen barrier?
The sophisticated molecular, crystalline structure makes EVOH an extremely effective and powerful barrier against oxygen and other gases such as nitrogen, carbon dioxide and helium. The supply of oxygen is almost completely cut off.
Is EVOH a plastic?
What is an EVOH Barrier? Ethylene vinyl alcohol copolymer (EVOH) barriers comprise a family of extrudable plastic barrier materials with excellent barrier properties for oxygen and a variety of other gases and volatile products (flavor barrier).
Which is better an EVOH coating or alcohol based solution?
Such coating solutions have lower viscosity than equally concentrated solutions of EVOH in alcohol-based solvents and have greater shelf lives than alcohol-based solutions. Multilayer structures having an EVOH barrier layer coated on a plastic substrate from solution in aqueous tetrahydrofuran solvent have excellent oxygen barrier properties.
Why are the barrier properties of EVOH so good?
The excellent barrier properties of EVOH are attributed to the strong inter- and intra- molecular bonding caused by the polar hydroxyl groups present in the vinyl alcohol unit. [9,10,14]These hydroxyl groups are also responsible for the moisture sensitivity because
Which is the world leader in the production of EVOH?
More function, less waste Kuraray Co., Ltd. is the world leader in the production and development of EVOH (ethylene vinyl alcohol copolymer) barrier plastic raw materials. It is available worldwide under the name EVAL™, either in pellet form for coextrusion and coinjection, or as film for lamination.
What is the melt index of EVOH resins?
Coextrusion coating test. The EVOH resins selected for the study, were 32 mol%, 35 mol% and 44mol% ethylene EVOH. The first resin is a 32 mol% EVOH with melt index of 4.4 gm/10min at 190°C. the 44 mol% EVOH has a melt index of 5.5 gm/10min. Finally a 35 mol% EVOH polymer with a MI of 8 gm/10 min at 190°C was included in the sample set.