Chrmistry Project Glue Strength

[Quietfury]

We were asked to do a hypothesis based chemistry project, where we make a hypothesis and prove or disprove it using chemistry concepts.
My hypothesis was that if you mix Polyvinyl alcohol and polyvinyl acetate in different proportions, then the adhesivity of the resulting mixture will increase with increase in percentage of pv alcohol in the mixture. I know beforehand that the adhesivity increases till a certain point, and then decreases.
To check the adhesivity, I prepared four samples with varying proportions of PV alcohol and glued eight wooden blocks together using the four glue samples. Then, I applied forces on each pair of blocks, with the logic that if it took more force (weights) to prise them apart, then that proportion of glue was strongest.
I found that the adhesivity was maximum when there was 30 percent pv alcohol to 70 percent acetate. I need a strong chemical reason why this specific value gives maximum adhesivity. (Is it because the pv acetate needs tobreact completely? Is bond formation slow?) Is there even a conclusive reason for this, is the reason too simplistic for 11th grade chem, and is my project a bad idea??