Various plastic questions

[sam]

I just finished my first pair of skis (look for a journal soon) and am currently looking into the materials for a second. One of the things that I have been working on is trying to find a source for Polyamide 12. I noticed that Kingswood uses this material for their topsheets and after some research found that it would be ideal. Has anyone else looked into purchasing it? Also has anyone simply bought a sheet of normal UHMW-PE and used it for sidewalls? I figure its no different then durasurf except for the bond between it and the core which has never seemed problematic once the ski is put together. Thanks for the help.

-Sam

[G-man]

Once in awhile I get one of those credit card offers in the mail that includes a sample fake credit card with 'your name here' on it. Some of the cards are made from a totally clear plastic material that is very, very tough. In fact, the plastic that all of my credit cards are made from seem to be made of the same material. I have saved some of the clear plastic sample cards with the idea that I'd someday get around to doing some bonding tests on them. The plastic seems to be at least as tough as UHMW, it's totally clear, and seems like it might bond well. Does anyone have any idea what the plastic material that credit cards are made from might be? I think it's a thermo-plastic, so it could also possible work well for heat-added vacuum-pressed cap construction.

G-man

[mattman]

g-man, from as far as i can tell, credit cards are typically made from pvc. this easily comes in clear (think vinyl sheeting), and thermoforms great (check out the info on sites for credit card printing services). i would imagine bonding will be at least as difficult as with abs. we have had great luck with thermoforming clear uhmw for topsheets in cap construction. you just have to make sure to take the shrink rate into consideration (but that goes for any plastic). if there is any supply for Treated For Bonding ABS sheets, that would thermoform with MUCH less shrinkage than UHMW.

[G-man]

Thanks mattman,

I did, in fact, run across the credit card printer sites a couple of weeks ago, but hadn't gotten around to posting about it. One of the sites lists a composite material that is a mix of pvc/pet that is supposed to be quite tough. I haven't bond tested my sample credit cards yet, but one of these days I'll get to it.

In my searches around the internet, I haven't run across any company that supplies pre-treated ABS. Have you noticed any reduction in surface treatment quality with the UHMW after thermoforming?

Thanks again for taking the time to post the info.

G-man

[mattman]

we have had absolutely no problems with the TFB surface after thermoforming. in fact the surface looks identicle after, we just do a solvent wash before the layup. the trick is to try and form at as low of a temperature as possible to reduce shrinkage (250F seems to be that limit).

[rockaukum]

Hey guys, In my past life I worked for a check printer and they also printed these bank cards. This may be another lead into further information. When witht he company they had printing faciilities in Livermore and Fresno, however they were about to close one when I left the company. Check into the Sunday ads for discount check printing services and try calling to get plant information. These discount houses print the same checks for the bank and there for should be doing the bank cards. Just a thought.
ra