Is this a good example of the strategy pattern?
It seems like a you should implement Chain of responsibility as you are passing the same string to different kind of processor with a particular sequence

http://www.dofactory.com/Patterns/PatternChain.aspx#_self1

This is a gud pattern in your scenario. 

One more thing your StringProcessorChain might not be needed in this case....

Let me know if you need a more highlight on same