Finding property data for materials, chemicals and other substances can range from easy (if the substance and the property are relatively common) to the most difficult piece of information you've ever tried to find (if the substances and/or properties are uncommon.) The time and effort involved varies just as much and can be hard to predict.
On this page you'll find instructions on how to do an extensive search of the literature.
It's the database with the greatest range of both substances and properties. Knovel will also help fill in the knowledge gaps if you are unfamiliar with your substance or property.