View source for Barrier material

== Description ==

A material, such as plastic, paper or metal, that is impermeable to gas or liquid. Modern barrier materials are usually made from lightweight transparent plastic sheets whose goal is to reach the barrier properties of a metal or glass. Metal sheets, such as [[aluminum foil]] have good barrier properties. They are often laminated with [[polyethylene]] and/or [[nylon%20resin|Nylon]] film to provide tear and corrosion resistance. Some plastics also work well as vapor barriers ([[polyvinylidene chloride]], [[polyester%20resin|Polyester]], rigid [[polyvinyl chloride]], [[polychlorotrifluoroethylene]], [[polyvinyl fluoride]]) while others are best for moisture (Polyvinyl chloride, [[regenerated cellulose]], Polyethylene, [[polypropylene]], [[polymethyl methacrylate]] (Hatchfield 2002). Multiple materials are laminated for optimized barrier properties. For anoxia treatments, films with low oxygen permeability are best. 

=== Barrier Films ===
Single layer barrier films, such as used for short term applications include cling wrap (polyvinylidene) shrink wrap (polyethylene) and nylon (polyamide) films. Double-layer films made by thermoforming one material to another provide a better balance of impermeability to both moisture and oxygen, thus providing protection for longer durations. Multi-layer films provide the best protection and usually include combinations of the following: Ethylene-Vinyl alcohol (EVOH), aluminum foil, metallized polyester, nylon, and polyvinylidene chloride.  Polyethylene and/or polypropylene are often used to adhere layers together.  Some commercial brands form barrier films include:

{| class="wikitable" style="vertical-align:bottom;"
|- style="font-weight:bold; background-color:#FCE4D6;"
! Tradenames
! Composition layers
! Thickness (mils)
! Water-vapor transmission gm/m2 per 24 hours
! Oxygen transmission cc/m2 per 24 hours
|-
| [[Marvelseal 360]]
| [[nylon]]\[[polyethylene]]\[[Aluminum foil]]\[[polyethylene]]\LLDPE
| 5.2 Mils
| 0.009 (90% RH, 100°F)
| 0.009 (@ 0 RH, 73°F)
|-
| Marvelseal 470
| [[polypropylene]]\[[polyethylene]]\[[Aluminum foil]]\[[polyethylene]]\LLDPE
| 5.0 Mils
| 0.009 (90% RH, 100°F)
| 0.009 (0 RH, 73°F) 
|-
| [[Aclar]] UltRx 6000
| [[polychlorotrifluoroethylene|polychlorotrifluoroethylene]] 
| 6.0 Mils  
| 0.0047 
| 27.9 
|-
| Peralux
| [[Polyvinyl chloride]]\Aclar
| 6.0 Mils  
| 0.03 (90% RH, 100°F)
| 14.8
|-
| kp (Pentapharm)
| [[polyvinyl chloride]] (PVC)\Aclar\PVdC\PVC
| 3.0 Mils  
| 0.35 (38°C 90%RH)
| 0.18
|-
| Filmpak 1193
| [[Polyester]]\[[polyethylene]]\[[Aclar]]\Polyethylene
| 4.9 Mils  
| 0.03 (90% RH, 100°F)
| 0.05 
|-
| [[Escal|ESCAL]]
| [[polypropylene]]\Silica deposited [[polyvinyl alcohol]]\ LLDPE
| 114 microns
| 0.01 (25°C 60%RH)
| 0.05 (25°C 60%RH)
|-
| EVOH/nylon barrier film
| [[EVOH]], [[nylon]]
| 3.0 Mils  
| 
| 2.3 cc/m2 per 24hr.
|-
|}

== Synonyms and Related Terms ==

barrier plastic; barrier film; barrier board; vapor barrier; vapour barrier; air barrier; air infiltration barrier; Marvelseal® 360; Marvelseal® 470; Aclar® [AlliedSignal]; Filmpak 1193; Film O-Rap [Bell Fibre]; ESCAL; EVOH/nylon; Sperrschichtmaterial (Deut.); matériau barrière (Fr.); barreira (Port.)

== Resources and Citations ==
* M.Elkhial, N.El Hadidi, [https://heritagesciencejournal.springeropen.com/counter/pdf/10.1186/s40494-022-00663-z.pdf 'Assessing the suitability of new film laminates for sustainable insect eradiation by modified atmosphere in museums'], Heritage Science, 10:28, 2022.
* P.Hatchfield, ''Pollutants in the Museum Environment'', Archetype Press, London, 2002. 
* J.Burke, "Vapor Barrier Films" WAAC Newsletter, Vol 14, No. 2, 199, 13-17.
* Boise Cascade Paper Group, ''The Paper Handbook'', Boise Cascade, Portland OR, 1989
* ''Dictionary of Building Preservation'', Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971  Comment: p. 578
* Conservation Support Systems, Catalog, 1997 [https://conservationsupportsystems.com/product/subcategory/barrier-films Barrier films]
* Theodore J. Reinhart, 'Glossary of Terms', ''Engineered Plastics'', ASM International, 1988
* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000



[[Category:Materials database]][[Category: MWG]][[Category: Sheet/Film, Composite]][[Category: Laminates]][[Category: Comparisons]]