Abstract:
|
This project is focused on acrylate derivative resins for automotive adhesives and sealants
applications. The acrylic terpolymers are synthesized via an innovative process called SET‐LRP (Single
Electron Transfer – Living Radical Polymerization).
Adhesives and sealants manufacturers commonly employ just one single resin as the
backbone of their formulations. The novelty is to experiment with blends of resins to improve the
performances of the final commercial product. This work has studied the impact of the functionality
(mono‐, di‐, tri‐), molecular weight (10K g/mol to 30K g/mol), and bimodality (MW and functionality
mixture) on compression set, tensile strength and elongation at break, compressive stress relaxation,
and storage modulus as well as the impact on glass transition temperature in well‐defined blends of
acrylate polymers prepared by both ATRP (Atom Transfer Radical Polymerization) and SET‐LRP
processes.
It is well‐known that resins for automotive applications need an oil resistant monomer (ORM1) in their composition to protect the material from the attack of the lubricant oil during their work life. However,
neither its role nor its efficiency is very well understood. In this project, the influence of the different
proportions of this oil resistant monomer (0%, 2.5%, 5%, 7%) in single heteropolymers based on acrylate
derivatives has also been studied. Compression set, tensile strength and elongation at break, oil
resistance, storage modulus and glass transition temperature have been used to investigate the true
role of this monomer in the resin composition.
Analogous investigations were undertaken on blends of terpolymers based on acrylate
derivatives varying the total amount of the ORM1 (3.5%, 5%) in the resin blends. The
same experimental techniques were used to characterize the influence of this monomer in
the resin blends. Attention was also paid to the type of capping in both resin blends. In one blend,
the resin was capped with acrylate and the other contained both acrylate‐ and methacrylate‐capped
resins.
The fact is that the need for the ORM1 in the composition was not clear enough
in light of its toxicity and irritant status. An idea was to replace this monomer by another oil resistant monomer (ORM2) which is an irritant but does not carry a “Toxic” label. Several experiments were
performed using a single copolymer resin without ORM1 in the backbone, but
introducing ORM2 as diluent/reactive monomer. A comparison with the same
resin, but with dimethylacrylamide as a diluent monomer, which is habitual in the practice, was also
done. Also in this experiment compression set, tensile strength and elongation at break, storage
modulus as well as glass transition temperature were studied. |