In a new work, scientists demonstrate the effect of introducing chemical cross-linking on the mechanical, thermal and structural properties of spray coated polyurea.
The introduction of long-chain amine improved the characteristic properties of the polyurea coating. Source: doctor-a / Pixabay.
Among the many desirable properties of polymeric coatings, the most important include ease of application, rapid cure time, adhesive properties and excellent mechanical properties. In this context, spray coated polyureas are finding increasing applications in niche areas that otherwise pose considerable challenge to the traditional coating chemistries.
A long chain trifunctional amine was introduced as a co-reactant in the resin blend, the amount of crosslinker being varied from 0 to 3.5 mol % (crosslinking density 28–180 mol/m3, affine network model). The mechanical properties of spray coated polyurea films, both in quasi-static as well as dynamic conditions were determined. Physically crosslinked polyurea coatings (in the absence of chemical cross-linking) exhibited tensile strength ∼ 7.4 ± 0.7 MPa and elongation of 121 ± 3.7%.
Introduction of long chain amine led to an improvement in these characteristic properties till maxima at 2.2 mol%, subsequent to which both strength and elongation decreased. Chemical cross-linking led to restraining of the segmental motions reflecting in terms of increased glass transition temperature, as evidenced by dynamic mechanical analysis and differential scanning calorimetry. The chemical resistance of polyurea also improved substantially due to crosslinking, which reflected in terms of decreased swelling ratio in different organic media.
The study is published in: Progress in Organic Coatings Volume 123, October 2018, Pages 201-208.
Making coating systems more environmentally compatible is a burning issue for everyone in the industry, and one that is being fuelled by the European Green Deal. Learn all you need to know about sustainable coatings, how to produce coatings in a more environmentally friendly way and how to give coated products a longer service life. You will find an overview in the EC Tech Report of the many various approaches being adopted. We will dive deep into the European Green Deal, its key points and main purpose as well as consequences for the coating industry, see which new raw materials are being developed to replace or lower the content of products in the SVHC group and learn about different approaches to sustainable paint formulation.
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