cmtaylor & MMF -
Now that you mention it, I do remember that many early plastic kits, and toys, were made of a very hard and brittle plastic that would easily crack, break, or shatter. [:(] Maybe it was that stuff that the article was referring to. I now have two more possible answers.
Lets hear from someone on the FSM staff. Why are you ignoring this post? If your archives are cataloged properly, you should easily be able to find that article. [;)]
Pete
Hi,
I work with plastics, the only time I heard about something eating plastics,
its about grocery store plastic bags, there was an experiment about adding
bacteria that eat plastic bags. This would end the problem at landfills.
But normally Low Density Linear Polyethylene are made in such a way that
they would degrade with ambient conditions like sun, uv rays and other factors.
The other factors that can destroy plastic in the case of HDPE pipe is rats,
mouses, and other kind of otters and animals that live under ground, thats
why when placing an under ground plastic pipe line we put some grabble and
sand bed, so animals like this dont reach pipe. Rats like some plastic additives.
But usually plastic last for life.
About bacteria or viruses, platics are poruse material, that can get impregnated very easy of dirt or other stuff, so this may be for some plastics, like others had demonstrated good thermal and permable barriers, like new packing materias for meat and vegetables that let air go out but not in.
Also, when we speak of “plastic” we are generally talking about synthetic resins formed by condensation or polymerization. But the term plastic is not limitted to those types of material. Up until at least the70’s certain cellulose derivatives (which are not synthetic resins, but are considered plastics) were used in injection molding, like ethyl cellulose, cellulose acetate, celulose nitrate. These cellulose deivatives are not as stable as was once thought (which is why the original prints of so many old movies are in danger, they were printed on cellulose based flim). I don’t know if scale models were ever made of cellulose plastics. But they were used in chess and checker pieces, dice, things like that.
Yes, thats true, Plastic have two sub sequent divisions for easy of study: Thermo Plastics and Thermo Sets. Thermo Plastics are easy to mold by heating and cooling and later we can recycle and we can recycle and continue the proces for some time (each time it would be degraded). On the other hand, we have Thermo Sets, this kind of plastics from Cellulose Derivatives once they are compunded and prepared they have a soft or kind of liquid aspect, they they are placed on a mold, usualy compresion mold, you put the plaster or mass of this material, then you cure it by pressure and heat.
But this material can not be recaycled to be the same plastic, since it has gone through a Chemical Reaction with non reversible conditions.
Some models, like Resine ones (Resine Figures, Accessories and Models) are made up of Thermo Sets, which are molded through compression system.
But now in days you can find models made up also of Resin, which is a Thermo Set.