What glue will mend Poulan Pro 117 trimmer plastic?

I have a Poulan Pro 117 string trimmer. The shield over the trimmer head has cracked. It is a black, stiff but bendable plastic type material. What is the material, and/or what glue can be used to mend it? I want a glue that will soften/dissolve the plastic to cause the plastic to reattach to itself.
Thank you - Jay Cox