Why is DPG used in silica-reinforced rubber compounds?

Further, while reacting with the silanol groups DPG reduces the polarity of silica by being adsorbed onto the silica surface [, , ]; and finally, DPG is also capable of accelerating the silanization reaction [2, 4, 7, 8]. DPG therefore has turned into a multi-purpose compounding ingredient in silica-reinforced rubber compounds.

What is the relationship between DPG concentration and bound rubber content?

3.1.2. Bound rubber content as a function of DPG concentration in the MB Total and chemically bound rubber contents are plotted as functions of DPG concentration in the MB: Fig. 8. The amount of chemically bound rubber as well as total bound rubber increase along with the DPG concentration in the MB.

What is the role of 1,3-diphenyl guanidine in silica-reinforced rubber compounds?

The aim of this study was to evaluate the various roles of 1,3-DiPhenyl Guanidine (DPG) in silica-reinforced rubber compounds. Two roles of DPG are well known to be: adsorption onto silica surface to reduce the acidic sites and second to boost the silanization reaction as secondary accelerator. However, these two roles are in a way conflicting.

Does 1 3 diphenyl guanidine affect vulcanization in silica-reinforced rubber?

This induces faster filler-polymer coupling, more bound rubber but slower vulcanization and lower crosslink density. DPG and TESPT are partly consumed during mixing and alter the network structure. The aim of this study was to evaluate the various roles of 1,3-DiPhenyl Guanidine (DPG) in silica-reinforced rubber compounds.

Why do CR and DPG molecules occupy silanization sites on the silica surface?

However, this explanation is in conflict with the results of chemically bound rubber and CR (Figs. 8 and 10): the high degree of silanization as well as a large amount of chemically bound rubber obtained there, even when DPG molecules would occupy the silanization sites on the silica surface by adsorption.

Does the silica surface adsorb DPG during vulcanization?

They found that desorption of DPG from the silica surface and crosslink formation of polymers occur simultaneously during the vulcanization process, where the latter is faster. Consequently the silica surface tends to adsorb DPG rather than to release it.