The shear strength enhancement due to fumed silica addition is even more striking. Adhesive shear strength typically increases more than a thousand-fold compared to films without particle reinforcement. The chemical bond formation in these adhesive films caused by adding fumed silica dispersions is currently being investigated, as this enhancement level was unexpected. Regardless of the shear strength enhancement source, the film cohesive strength increase is significant. The peel strength of the PSA films with and without fumed silica reinforcement was also evaluated (with a ChemInstruments Adhesion/Release AR-1000 peel tester). A 7-lb weight was used to roll 10 x 1-in. adhesive strips onto a stainless steel adherent at a controlled rate; the time lapse between the end of rolling and the peel test was 1 min. The reduction in peel strength due to fumed silica reinforcement is fairly modest: over a range of 0 to 4 weight % fumed silica, the peel strength decreases to ~ 75% of its initial value linearly. No further reduction in peel strength is observed between 4 and 8 weight % fumed silica. No tackifiers were used in the PSA data discussed here. For products requiring high adhesion via tackifier addition, reinforcement via fumed silica has been shown to more than compensate for the shear strength loss caused by tackifier addition (e.g., Tacolyn 3509). The 20-40% loss in shear strength caused by common tackifier levels is easily recovered via 2-4 weight % fumed silica reinforcement. If you are looking for high quality, high purity and cost-effective Fumed Silica, or if you require the latest price of Fumed Silica, please feel free to email contact mis-asia.