tensiletest

Hello, I am currently writing my thesis, where I have to investigate if a surface treatment increases the adhesion (between tape and a plastic surface). For this purpose, I have among other tests, performed a tensile test between the tape and plastic surface. The tensile test can be seperated in two: 1)To test the adhesion between tape and plastic surface (when the plastic surface has not been treated). I will mark the results 2) To test the adhesion between tape and plastic surface (when the plastic surface HAS been treated) My results are: 1) The mean for the maximum load is: 29 Newton. It was possible to pull the tape 10-20 centimeters of the plastic surface, before the tape broke. 2) The mean for the maximum load is: 25 Newton. It was possible to pull the tape 5 centimeters of the plastic surface, before the tape broke. I think that the test results from ”2” (with surface treatment) indicates that the surface treatment increased the adhesion. But the mean for the maximum load is smaller here. I do not understand. What can I concluded from these results and how can I explain them?