How can I search materials in SW 2018? For example: I want to search and select, Nylon 6/10.
This has been considered in the enhancement requests for at least a couple of years. I do not believe that what you seek is available.
(Aside, I think that everything which contains many things should be searchable: design library, material library, maybe appearances or weldment profiles, etc. Others have brought their own ideas to this list in the past.)
Once you do find the materials you want, I recommend to manage it in Favorite materials so that it is easy to find and sorted usefully.
Tom is correct that it is not available in the currently released versions of SOLIDWORKS. But, you may want to sign up for SOLIDWORKS 2020 Beta and check out the What's New guide (page 22 in the English version).
I still use SW 2019, but seems like it's now available in SW 2020. Check this tutorial: How to Search for Materials in SOLIDWORKS 2020
Or create a new material library and put (copy) material you use there.
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