(1) Glue
Crystalline rubbers, such as NR and CR, have high inter-intermolecular forces and strong mutual entanglement, so they are self-adhesive. Non-crystalline rubbers such as SBR, BR, and NBR are the second, and IIR and EPDM are the worst. Their adhesive force (kg / cm) compared below:
NR(12.5)>SBR,BR(5.6)>IIR(3.7)>EPDM(1.7-2.5)
(2) Additives
Due to the small molecular volume and good fluidity, the softener can penetrate into the middle of the rubber macromolecular chain, and open the macromolecular chain spacing to facilitate diffusion. However, some commonly used softeners, such as paraffin and stearic acid, are not conducive to self-adhesive because they are easy to spray out the surface and hinder the interface from salting. The tackifier is most effective for enhancing the self-adhesive force because they have a group such as an ester group or a hydroxyl group on the surface, and typical varieties include rosin, terpene resin, and xylene resin. The filler is similar to the softener. Some varieties, such as carbon black, are beneficial to self-adhesiveness, while others (such as talc) have a negative effect.
Operating process
From the technical point of view, the ways to improve self-adhesive are:
1) mixing NR;
2 Wipe the rubber surface with a solvent to allow small molecules of solvent to enter the rubber surface to promote mutual diffusion;
3 Heat and pressurize the bonding parts to enhance the molecular thermal motion, so that the molecules at the interface are closer.
