Chemical Bond
Plast-aid chemically fuses to compatible plastic on a molecular level, which creates a very strong bond even when the surface is smooth.
Plast-aid chemically fuses to many plastics (ABS, acrylic, PVC) and not others (Teflon, PE, PP).
The difference between a chemical and mechanical bonds is that material that chemically bonds can join very smooth surfaces. While a mechanical bond must be rough to work.