Digital BW, The Print

mrjimbo schreef:
> You may have something there.. I am not really sure how it ends up 
> shaking out.. The acrylic material itself changes over time.. I was 
> of the understanding that acrylic over time becomes harder and more 
> brittle and in that change process looses some amount of it 
> properties of which UV protection is one of.  I can say that exposure
>  to direct sunlight for extended periods actually change plastics
> very very quickly. 
> 
> jimbo

Pure PMMA is one of most stable plastics around regarding sunlight
exposure (UV included). It is more brittle than PC, PET or PVC when new
and later on. In practice PC gets UV blocking surface layers
(coextrusion) for outdoor use but PMMA not. Where PVC gets plasticisers
added to give more flexibility that isn't done with PMMA. Transparent
PMMA withstands some decades of outdoor exposure. It becomes a bit more
brittle in time and the material stress created in the production
process (vacuumforming, extrusion) may show cracks later on due to
temperature changes and mechanical impact. Indoors and produced as a
flat  sheet/panel in the casting process, there is little change in the
structural strength over time. It shows like many plastics electrostatic
behaviour so it can get filthy. It scratches faster than glass but less
than PC. There are varieties with a more scratch resistant coating.



-- 
Met vriendelijke groeten,   Ernst

Try: http://tech.groups.yahoo.com/group/Wide_Inkjet_Printers/

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