Join two part images

Another option you may wish to consider is to photograph the artwork with a camera. In fact, if you have a smartphone, there are a number of free scanning apps that work well.  However, depending on the nature of the artwork, you have to pay close attention to the lighting.

Yes, it's possible if your scans can line up.  Here is the workflow shown in my screenshot below:

1. Open both parts of your scan.  (I am assuming you are scanning the left and right side of the art work in this example).  Also create a new blank file from the File>New menu.   The size of the new file needs to be large enough to fit both parts of the scan into it.
2. Select the new blank file and drag the first scan from the photo bin into it.  Depending on the dimensions of the images and the new file, the scan will end up in the middle of the new file as a new layer. 
3. Use the Move tool to drag the layer into the correct position.  (The left side of the new file in my example.)
4. Do the same with the second part of the scan.  (Drag it to the new file and line it up with the first scan.)
5. The end result.

If the scans are not completely lined up, you can either use the straighten tool or the Transform tool (Ctrl+T) to rotate the scan layers into the correct position.

Also, it would be better if you scanned the artwork to a TIFF or BMP format rather than a PDF. 

I don't know what your level of experience is with Elements or what version you are using.  If you need more help, let us know.