Melamine [BSA]

Thermosetting polyester coatings crosslinked with hexa(methoxymethyl)melamine (HMMM) are ubiquitous for the pre-painted metal sheet used in white goods and architectural cladding. The coatings are typically 20 mu m thick and must have superior resistance to cracking during the forming process to maintain their excellent aesthetics and corrosion resistance. Hence, understanding their structure-property relationships is key to design durable coatings with good formability. The thermo-mechanical properties of clear and TiO2-pigmented polyester-HMMM free-films with varying number average molecular weight (MW) from M-n =1500 g/mol to 3300 g/mol and a constant crosslinker content of 20 % have been determined, and this work provides a fundamental investigation into the effects of varying the MW for the first time. Increasing the MW decreases the glass transition temperature (T-g) as the crosslink density reduces due to fewer functional chain ends. The Young's modulus and yield stress decrease with an increase in MW at low temperatures, and the strain to failure increases around T-g. The TiO2 pigment increases the stiffness of the coatings and reduces the strain to failure around T-g, but has a toughening effect at higher temperatures. All the coatings show comparable behaviour in the Erichsen cupping test; however, increasing the MW reduces the damage during the T-bend test as the coatings are able to withstand higher applied strains. Thus controlling the MW allows a balance of properties to be achieved, as increasing the MW reduces the T-g and modulus while increasing the strain to failure and formability of the coating. Such an understanding of the structure-property relationships allows for better formulating and targeted coating design, reducing cost and increasing performance in the coil coating industry.

Novel 3D P-doped poly(triazine imide) (PTI) nanotubes were prepared in situ by molten salt method with melamine and hexachlorotriphosphazene as starting precursors. The as-prepared composite showed superior photocatalytic properties under visible-light irradiation due to the integrated merits of 1D tubular structure, 1D nanorods, and P doping. The improved utilization of visible light and the enhanced separation of photo-induced charge carriers resulted in the maximum degradation rate constant of P-doped PTI at 2.86 min(-1), which was approximately 6.3 and 2.6 folds those of bulk graphite-like carbon nitride and pristine PTI material, respectively, during tetracycline hydrochloride photodegradation. Moreover, the novel catalyst has an excellent stability and thus is a promising candidate for photocatalysis.