# Creating 'material-sciences', was: merging polymers and plastics

In the spite of , , ... , , ... , I would like to propose a tag to be called "" or "". (In line with physics.se as this is an overlapping field.)

The scope of is not defined yet, there is no tag wiki and not even an excerpt. At the same time we have the , where I have created a very short description some weeks ago. I am no expert in the field, so I cannot be sure that i defined that well. When is comes to it just states

A large molecule (macromolecule) composed of repeating structural units.

This is also very broad. I understand that people in that field will be able to distinguish between those tags naturally, but will an average asker be able to?

Another question is, would those tags attract different users to read them? We are not an experts only site - this might come as chemistry.se develops into something bigger. I am thinking along the line of math.se and math overflow.

As with theoretical-chemistry, quantum-chemistry and quantum-mechanics I would suggest merging those tags into a more general tag. (We have not reached a conclusion there).

Plastics are often polymers, and polymers are often plastics, and as a result, in common language we often conflate the two.

However, there are key differences in how they are defined scientifically.

Plastics are defined based on their material properties - how do they respond to an applied stress?

Polymers are defined based on their molecular structure - how are the atoms that make them up connected?

Plastics undergo irreversible deformation in response to an applied stress, but still retain some of their shape - they are viscoelastic materials.

Polymers are made of long chains of repeating molecular subunits (long is a relative term, usually on the order of 100's of subunits minimum, up to 1,000,000's or more)

So, I do not think they should be merged, although very often a subject might have both tags, they are in fact separate concepts.

For example, wet clay is a plastic material, but is not a polymer, and $SeO_2$ is a polymer, but is not a plastic.

• Would you then agree that plastics are within the scope of materials? May 29 '14 at 1:31
• Sure, but I would say that materials is a sufficiently broad topic that plastics could have its own sub-category: "viscoelastic materials." I guess the real question for me is, what is the goal? Are we trying to limit tags to the ones that people are likely search for, without getting too specific? May 29 '14 at 1:46
• This should be the goal. Community editing is nice, better would be, if tags define the scope of questions from the start. This way they will get the most attention from people in that field. Having too specific subgroups of tags will only lead to people not using them, or using them wrong. Basically what I am asking is, would a question tagged with either attract different people to read it? May 29 '14 at 2:13
• I would say that experts in either field would certainly read the tags differently, although there would be considerable overlap. Most polymers people have some idea about the material properties, and most viscoelastic materials people understand at least a little bit about molecular structure. Lay people, on the other hand, are not likely to know the difference. In fact, when I describe my research to people (polymers), I usually just tell them it's what plastics are made out of, and then everyone is happy. May 29 '14 at 2:35
• I have edited the question. I think the scope of this site is more focused on the "lay", at least a thought that reading tour it. May 29 '14 at 2:57

Polymers are the organic chemicals that contain 10000+ repeating units. Plastics are the engineering materials which often transformed from the raw polymers and contain more than polymers such as plasticisers and pigments. Though whether you really need the distinction is a fair point. I'd say the other tags mentioned aren't well named- its the chemistry site so -chemistry is redundant but its probably not worth changing it.

• The most popular tag on a given question is appended to the question "slug" (unless the term is already included), so the text on the tag isn't really redundant as it's important for things like SEO. May 27 '14 at 21:20
• If plastics is an engineering thing, than it should probably merged with materials. In my university in the chemistry faculty the different fields were all appended -chemistry. I did not find that redundant and neither do I think that here. May 28 '14 at 4:19