Material compatibility

[Lane]

I have an idea for a project but wanted to check if there are any known issues with the materials I want to use.

I recently found a product at a local plastic supply company that I think would work great for modular terrain boards. It's a PVC foam, light bit fairly stiff and impact resistant.

The question I have is compatibility with Styrene. Has anybody used PVC, any type not just foam, in contact with Styrene long term? If so was there any sign of softening the Styrene.

[mangozac]

Hi Lane welcome to RA. Honestly this is not something I would have even considered. I assume the issue is the gasses released by the PVC as it ages acting as a solvent on the styrene? In modelling people often seal surfaces using PVA glue - I wonder if that would be applicable here.

You might be best to email the material manufacturers to find out...

[Lane]

I have seen several references to PVC electrical insulation, including cords for computer peripherals, melting polystyrene foam so I thought it a good idea to ask. The main difference I see with PVC insulation and PVC foam is that the insulation has plasticizers to make it flexible and those are what melt the styrene.

I want to use these PVC foam sections as additional tiles in a GW Realm of Battle Board set, being styrene and probably in contact with the foam tiles could be a problem.

What prompted me to ask was I recently found a couple model bits that had been in contact with Sculpey (polymer clay) and the styrene had melted from the clay.

It may be OK to just coat the PVC to prevent direct contact.

[Munkey Joe]

[mangozac]

Wow how bizarre. Even more so due to the fact that the Lego is ABS, not styrene! I've got no idea what could be causing it - perhaps it's to do with the pressure? Come to think of it the guys who sculpt with sculpey always use metal tube and rod for parts so perhaps this is why...

Honestly, I wouldn't be too worried about the rigid foam melting the styrene. And if you are worried a coat of PVA should be adequate to seal it.

Edit: Just reading some stuff online and seems to confirm what is being discussed here.

[Lane]

[Munkey Joe]

[mangozac]

That's funny. I would have thought the uncured sculpey stickier than clay. Were you using the right sulfur-free stuff for professionals (i.e. not the rainbow coloured kids packs from the newsagent)?

[Lane]

[Hatemonger]

Back on the original topic, I have had resin melt styrene also. I had a styrene-built house as a master, and I thought, "Hey, if I fill this up with resin, it will be more sturdy for casting and playing."

After a while, I noticed all kinds of bubbles on the surface, which were soft like flexible goo. Needless to say, I was not happy, as I was hoping to preserve the original, not wreck it. It also ruined a vac-formed terrain piece I had similarly filled.

Is it normal for urethanes to attack styrene like that, or is this likely peculiar to the specific resin I used?

- H8

[Lane]

Could have been a problem with the resin. I've had cast parts that after a couple weeks started to sweat an oily substance that melted styrene.

Was the resin old, starting to get crystals in the (IIRC) B side?
Was the resin properly mixed in the right proportions?

Either of these could have changed the chemical makeup of the resin and prevented proper curing.

[mangozac]

I'd be surprised if that happened to me using urethane resin - perhaps as Lane suggested the resin wasn't mixed properly - it would make sense that in their unreacted states they will act as a solvent to styrene. It's all petrochemical based, right?

Now that I think of it I've never poured resin into contact with styrene, only silicone. People have often suggested to fill hollow parts with resin though if being put under pressure for moulding, so I'll have to take this into account if I ever decide to and do a test first. I think I'd have a mental meltdown if a master part melted!

[Munkey Joe]

[Dragonforge]

Are you talking about PVC foam board like Sintra or Kimatex? Both brand names by the way.

No issues with bonding it to styrene. A CA glue is the preferred adhesive of choice. I do it all the time.

[Lane]

Not sure of the brand, I'll have to see if I still have the receipt. Good to hear at least some PVC is compatible.