UV stabilized plastic reccomendation
UV stabilized plastic reccomendation
(OP)
I have a thermoformed HDPE cover that is used outdoors as a machine guard. After a few months in service the part becomes brittle and fails. Can anyone reccomend a material that has similar mechanical poperties with enhanced UV stability? The color must be white or a carbon black would be substituted. Also the production volume is fairly low so a higher priced stocked material would be preffered to an X ton minimum order. Would a TiO2 additive help?






RE: UV stabilized plastic reccomendation
http://en.wikipedia.org/wiki/Royalex
H
www.tynevalleyplastics.co.uk
RE: UV stabilized plastic reccomendation
Firstly, the HDPE would work with carbon black and proper UV stabilizers. Other alternatives are PP and ASA (the latter much more expensive).
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: UV stabilized plastic reccomendation
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: UV stabilized plastic reccomendation
Regards
Pat
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RE: UV stabilized plastic reccomendation
But, I also think the OP owes three stars for the prior posters, all of whom gave quite good info., as usual.
RE: UV stabilized plastic reccomendation
RE: UV stabilized plastic reccomendation
Not all pigments of the same colour offer the same UV protection.
eg, Carbon black is impervious to UV light while Nigroseine has no effect at all. Both are black.
Also particle size and quality of dispersion of the pigment has a significant effect om results.
Regards
Pat
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RE: UV stabilized plastic reccomendation
RE: UV stabilized plastic reccomendation
Regards
Pat
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RE: UV stabilized plastic reccomendation
RE: UV stabilized plastic reccomendation
RE: UV stabilized plastic reccomendation
UV stable PE should process the same as all you need is 1 % carbon black and the right UV stabilizer, e.g. HAS (also known as HALS in the old literature).
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: UV stabilized plastic reccomendation
If the supplier gives you a blank look when you ask what is the MFI, you can get a real rough idea by placing small offcuts of both, side by side in an oven and test them as they start to melt. If they are both about as bendy or malleable as each other you are probably OK. It is a real rough test, but might be all you have available.
Regards
Pat
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RE: UV stabilized plastic reccomendation
MFI isn't as important with thermoforming like it is with injection molding. There is a hot strength test which is more relevant (but I forget it's name).
I would worry more about forming temperature and shrinkage. The orientation of PE sheet is important and can make a big difference in the sag of the sheet and the shrinkage. However, if you ordering small lots you won't get to specify this.
RE: UV stabilized plastic reccomendation
MFI is used to attempt to describe how easy a plastic will flow in the mould It is used by pretty much injection moulders. It is a poor method but is easy to do and comprehend.
Molecular Weight is used by polymer chemists.
Melt viscosity is used by physicists.
Melt strength is used by blow moulders and extruders in a descriptive manner, but they still use MFI for a quantitative measure.
You want high melt strength which is low MFI. Fractional MFI is less than or a fraction of 1.
Regards
Pat
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RE: UV stabilized plastic reccomendation
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: UV stabilized plastic reccomendation
RE: UV stabilized plastic reccomendation
Chris DeArmitt PhD FRSC CChem
www.phantomplastics.com
Consultant to the plastics industry
RE: UV stabilized plastic reccomendation
RE: UV stabilized plastic reccomendation
It can only protect what is behind it, not what is in front of it.
Stabilisers that dissolve at a molecular level are required to protect the surface. There are numerous types and different modes of action. Different formulations are used for each polymer. To explain it in full detail would be a few hundred pages.
Grey "outdoor PVC normally contains TiO2 and carbon black to get the grey colour. It also contains some antioxidants (previously lead compounds, but now more likely tin compounds) and cheap mineral fillers.
Regards
Pat
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RE: UV stabilized plastic reccomendation
RE: UV stabilized plastic reccomendation
1. Anyone have recommendations on a UV blocking PP that is FDA compliant (injection moldable)?
2. If I wanted to spec a resin that blocks 90% of UV light from passing through how would I do so? Is there an ASTM spec? As I understand ASTM D1003 Haze isn't the right thing.
RE: UV stabilized plastic reccomendation
qtg836b: suggest you start a new thread rather than hijacking this one - you will get a better response.
You will also need to define your requirements much more than you have done...
H
www.tynevalleyplastics.co.uk
RE: UV stabilized plastic reccomendation
Regards
Pat
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