UV stable translucent inflammable polymer

[mark0310]

Glass seems to be the only suitable material for the bulb part of a lightbulb, because of all the demands on thermal,optical, inflamability and mechanical requirements....however I have a design need for a secondary off-white opaque covering adjacent to the glass bulb on a low-energy lightbulb.....effectively a second skin to the glass bulb but with a small (circa 5mm)air gap between them. This immediately removes the thermal demand but the optical (UV stability) and inflammable requirements remain.
I have looked at blow-moulding using PC or a PC alloy but am concerned about Yellowing of the cover.
I am looking for advice on the most suitable polymer to use.
Many Thanks
Mark

 

[Pud]

For 50C, PVC might be ok. Inherently FR and good UV too. Blow mouldable. Try a mineral water bottle!

H

http://www.tynevalleyplastics.co.uk

 

[mark0310]

Hi H,

Thanks for the suggestion, I'll try one out (and check for the markings on the base first!), however difficulty is knowing whether I'll get discolouration of an opal coloured one after a couple of years use?
I'll see if the suppliers do them in a translucent off white for 1mm thick.
Thanks again, Mark

 

[HDS]

The opal look bulbs I have seen on Christmas lights were painted on the glass.

How are you going to insure that there is always a 5mm gap? What happens if the bulb gets bumped or assembled wrong and the plastic touches the glass?

 

[mark0310]

Thanks HDS, If you take a standard Opal incandescent lamp, tulip or bulb shape, break the glass and check it out you'll most likely find it to be clear glass (sub 1mm thick) with a painted coating on the inner face.
I have considered using a clear PC and doing something similar because this is more tolerant to yellowing, but I'm hopeful that I can find a polymer, translucent but opal tinted that is coloured in the batch.
There's no problem working to the 5mm gap.
Thanks again, Mark

 

[lumenharold]

It's been a couple days since the thread has been active but I came upon an email sent to me last February: Pat mentioned Bayer and they do have a series of Makrolon (PC) products for LED lighting that might work. They are diffusing but translucent, UV stable and FR.

Makrolon LED2643, FR7087, 6717, and 3103

Harold
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nVidia Quadro FX4600

http://www.lumenflow.com

 

[patprimmer]

My original draft for my original reply recommended acrylic based on the heading of inflammable.

Luckily I realised the OP was not aware of the idiosyncrasy in the English language in that flammable and inflammable mean the same thing which is the opposite of non-flammable and flame retardant.

Regards
Pat
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[mark0310]

Hi Harold, thanks very much for the information on the grades of PC from Bayer that look suitable for this application. I'll contact them and see if they can send a tech sheet. And...I recollect the author JPDonlevy would start a new sentence with "And" ....many thanks to Pat for spotting my inadequate knowledge of flammable and inflammable, I certainly won't make that mistake again! But is would be an very perverse request to ask for a flammable polymer to use as a lamp cover. Thanks again. Mark

 

[patprimmer]

Mark

That is how I picked it up. I thought why on earth would he want that part to be flammable.

Regards
Pat
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[ornerynorsk]

Chris,

I may have missed it in the postings. . . Do I understand correctly that ThermoShift does not necessarily have a "normal" state and can be customized to go opaque to transparent OR vice-versa at that wide range of temperatures? When at its most opaque, what wavelengths are effectively blocked?

Would its properties make it suitable for a glazing material in architectural or agricultural applications?

It does sound like interesting stuff.

Regards, Ornery.

 

[patprimmer]

It's the most interesting development I have seen so far this century.

Regards
Pat
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[Demon3]

Hi Ornery,

Sorry for the delay in the reply, I've been away on business.

The best way to describe the ThermoShift is the movie of it in action on my website. It speaks louder than words.

You're right that you can pick whatever transparency temperature you want so that material is very tunable. One grade is transparent at -20C another is transparent at +80C and we can make anything in between. The material becomes opaque above and below your chosen transparency temperature.

The mechanical properties are just like ABS so a great balance of modulus, strength and impact resistance. To use it in glazing you'd have to add a film to protect it against UV light.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry