Preparation Of Melamine-based Benzoxazine/Shrimp Shell Composites And Research On Their Anticorrosive Properties

A novel kind of melamine-based benzoxazines has been synthesized using melamine, formaldehyde and phenol or Bisphenol A, and their composites with shrimp shell have been prepared. The structures and viscosity of the novel benzoxazines were examined by using proton nuclear magnetic resonance spectroscopy (1H-NMR), fourier transform infrared spectroscopy (FTIR), and Mini Rotary Viscometer (MRV), respectively. Thermal properties of polybenzoxazines have been studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The anti-corrosion performance of the polybenzoxazine/shrimp shell composites were also investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM).Experimental results have clearly demonstrated that the striking feature of the class of benzoxazines is the subtle combination of their inherently low viscosity at room temperature, good film-forming characteristics and high chemical and thermal stability. The benzoxazine from melamine, formaldehyde and phenol has a fluidity at room temperature, and their viscosity approaches 1 Pa s at 40℃. The polybenzoxazine films were easily fabricated by casting the benzoxazine monomers on glass plates under solvent-free conditions, and there were no bubbles and cracks on the surface of the films. The 5 and 10% weight loss temperature (T5 and T10) for the polybenzoxazine were approximatively at 350℃ and 380℃, exhibiting a high thermal stability.The polybenzoxazine composite with shrimp shell possesses a high anticorrosive performance. Since shrimp shell was added to it, the toughness, tolerance of salty and alkali corrosion of polybenzoxazines were significantly improved.This is the first time that the melamine has been anchored into the benzoxazine network, resulting in dramatic changes on viscosity, processibility and thermal stability. With the introduction of shrimp shell, the application of polybenzoxazine composites can further be broadened. Our research may open a new path for overcoming the present drawbacks of polybenzoxazines such as high brittleness, the difficulties in preparing films and poor processibility via tailoring the structures and properties of amine in the benzoxazines.