plastics and china

[cteno4]

interesting post on nscale.net. as plastic part production moves to china they seem to be changing the plastic composition. sounds like its more like the ABS in they tomytec kits than plain styrene.

 

http://www.nscale.net/forums/showthread.php?25325-China-made-heads-up-problems-with-plastic&p=249411#post249411

 

always something to wash your parts and test your glues!

 

jeff

[KenS]

My Tomix Gas Station (Eneos, #4064), which I've had for several years, doesn't say where it was made, but it's definitely not the usual styrene as testors glue doesn't affect it at all (which I found out the hard way, when a part I'd glued to it fell off the next day).  It's a slick, hard, plastic and does feel more like ABS than ordinary model plastic.

 

I'm no chemist, but from wikipedia it would appear that "styrene" is a chemical compound found in a variety of plastics. According to Plastruct, the stuff we think of when we say "styrene" is "Hi-Impact PolyStyrene". ABS ("Acrylonitrile butadiene styrene") is a slick plastic, half-again as rigid as hi-impact polystyrene. Technically it would appear correct to call both of them "styrene".

 

ABS, in my limited experience, seems to have less ability for forming fine detail, but is much more resistant to damage.  The latter is probably an advantage on the temporary on-the-floor layouts typical in Japan.

[cteno4]

styrene plastic is polystyrene (a polymer of styrene monomers). folks usually end up dropping the poly to just call it styrene, but thats technically not right. basic stuff used for most plastic models as its stiff but easily cut and moulded. takes bending to a point then snaps.

 

ABS is a mixture of 3 momomers; styrene, acrylonitrile, and butadiene. in the polymerization so you get polybutadiene chains that are crosslinked to chains of poly(styrene-co-acrylonitrile). yes most things out there these days that are called plastic are ABS as it has smooth shiny surfaces and takes a beating as the polybutadiene is a more flexible chain (to take the impact), but the cross linking makes it very strong from breaking. and as you point out is why its used for tomix and kato track roadbeds, it can take the abuse w/o snapping or cracking that polystyrene might give you.

 

it may be the tomix base is POM (Polyoxymethylene) or some other plastic mix that does not work with standard solvent based glues like testors. there are a world of plastics out there and they can be copolymerized and mixed in a lot of interesting ways.

 

sorry many many years of chemistry in the past... i just want to say one word to you. Are you listening? Plastics!

 

jeff