Photocured polyacrylate coatings modified by polybutadiene derivatives with multiunsaturated reactive bonds

Maleic anhydride-g-poly(1,2-butadiene) (MLPB) is used as a rubber flexibilizer to modify UV-curable polyacrylate coatings (PA) in an attempt to improve their wear resistance and water tolerance. Fourier transform infrared spectra results show that the unsaturated reactive bonds of MLPB fully participate in the UV-curing reaction and successfully copolymerized with acrylates to obtain robust coatings. The smooth and broad differential scanning calorimeter curves show that the cured systems had good compatibility and their glass transition temperatures (T_g) increase from about 63°C to 74°C with the increase of MLPB addition up to 6 wt%. With the addition of MLPB in PA matrix, their cross-sectional scanning electron microscope (SEM) pictures show brittle features with coarser and dimpled microcracks transforming to toughened fracture morphology with particles offsetting microcrack propagation when MLPB content is added up to 4–6 wt%. The wear scar profiles show that the cross-sectional areas decrease significantly with the MLPB addition, implying the improvement in the wear-resisting ability of PA composite toughened by MLPB; the hardness, impact resistance, and adhesion could be also improved when MLPB was controlled less than 6 wt%. Compared with the pure polyacrylate coatings, the modified coatings exhibited an improvement in water resistance before and after 48-h UV aging.