Tuesday, August 31, 2010

Polymers Go Nuts!

The latest item from the bio-polymers front is the announcement by NEC (described in this Design News article) of a material prepared from cellulose and cardanol. Cardanol is a phenol derived from cashew shells.

The developers aver that the material is a good candidate for electronic equipment housings and that it potentially can be cost-competitive with traditional alternatives. They say that they're shopping around for a manufacturer for the resin.

This development is certainly interesting on its own merits, but I think it draws attention to a broader point. That is, polymers in general can be agnostic with respect to feedstocks. At present, the economics of the industry favor fossil-derived inputs, but as we get around to fully costing in the externalities involved in the use of petroleum and natural gas there is a strong likelihood that other materials will become relatively attractive.

Hydrocarbons are hydrocarbons; in the long run it's all just chemical engineering!

Thursday, August 19, 2010

Purging Tip of the Week: #20

If heats are raised while purging and the flow of material is slowed or stopped, be sure that high throat temperatures don’t lead to premature melting of the purging material. This can cause causing “bridging”, where the pellets form a solid mass in the throat or in the feed zone and it can prevent the normal feeding of material by the screw.

If throat temperatures seem high (for example, if the throat casting is too warm to comfortably touch) you should keep the screw turning at low RPM so that the pellets remain in motion throughout the purging process.

Thursday, August 5, 2010

Purging Tip of the Week: #19

Chemical purging compounds require heat and containment to work effectively. When using products from this category, be certain to keep the throat full at all times during the purging process. If the throat empties the gases that are essential to good purging performance can escape prematurely, leading to disappointing results.

Tuesday, August 3, 2010

Oh, poo!

Now it would seem that there is yet another unintended consequence to be considered as jurisdictions move toward banning single-use plastic bags. As this article asks: "Without a collection of plastic bags under the sink, how do you get rid of dog poop?"

The linked article goes into considerable detail exploring alternatives - most of which turn out to be environmentally undesirable. (Hint: the author suggests searching "dog composter".)

It's not easy being green!