Polypropylene is a thermoplastic mouldable polymer material made from propylene. One of the many forms you can find polypropylene in is in large sheets in thickness of various inches. If you are working with these sheets, you will need to weld them together to form a firm connection. Melting a secondary material to bond the sheets together forms the welding process and can be easily done even without any welding experience.
Put on protective gloves and a welding mask and mitre the edges of the sheets towards each other with a saw. The angled edges will create a small channel to allow for a firm weld.
Cut the end of the welding rod with a trimming knife to a 45 degree angle. The point of the rod should be on the edge of the rod further away from you.
Slide the pointed end of the welding rod into the nozzle on top of the welding tool tip. The pointed part of the rod should be facing away from the tip of the tool.
Hold the welding tool directly above the seam you want to weld. The tool should be elevated off the sheets by the thickness of the rod. If your welding rod is 1/2-inches thick, raise the tool 1/2-inch off the sheets.
Push the welding rod down until the point touches the sheets. Make sure the point is pushed right down into the seam where the sheets meet.
Hold the tool in place until the welding rod is soft enough to be spread into the seam. Do the same at each section of the rod until you have firmly spread the weld onto the seam.
Pull the welding tool down and away from the applied weld and remove the welding rod from the tool.
You can tack weld or clamp the sheets in place if they are slipping around when you start to apply the weld.
Do not touch the hot weld until it is completely set or you will burn yourself.