Study Of Calcium Carbonate Crystal In Chitosan

Organic-inorganic composites with the regular structure and the superior mechanical properties are now of current interest for both organic and inorganic chemists. Chitosan/CaCO₃ composite with high performed, potential applicant was prepared by the method of in-situ precipitation and reaction. In order to control the morphology of CaCO₃ particles, the different soluble polymer and ion were introduced into the composites.1. Chitosan/CaCO₃ three dimensional composite was prepared by the method of in-situ precipitation. XRD was carried out to determine the presence of the CaCO₃. SEM was preformed to investigate the distributing regularity of CaCO₃ and the size of the CaCO₃ particles. It can be concluded that the particles of orbicular were distributed orbicularly on the cross section and its size was about 5 10micra. The mechanical properties of the composite were evaluated by three point bending test. The bending strength enlarged firstly and then dropped with the increase of CaCO₃'s mass content and modulus decreased continuously.2. Chitosan/CaCO₃ three dimensional composite was prepared by the method of in-situ precipitation and reaction. CO₃^2- ion that urea was decomposed reacted with Ca²⁺ to obtain CaCO₃. It can be concluded from the results of XRD that the crystalline form of two series of composites is calcite. The size of the CaCO₃ particles wasn't uniform and the shape of them was different. The bending strength also enlarged firstly and then dropped with the increase of CaCO₃'s mass content and modulus decreased continuously.3. In order to obtain the suitable crystal and the different morphologies of CaCO₃ particles, Mg²⁺ ions were introduced in the precursory solution and finally the chitosan/CaCO₃(Mg) composite was achieved. XRD was carried out to determinethe presence crystalline form of the calcium carbonate. SEM was preformed to investigate the distribution, the morphology and the size of the calcium carbonate particles. It can be concluded that the particles had the different morphologies with different content of CaCCb. The petallike particles were obtained in chitosan/CaCO3 composite (mass ratio, chitosan/CaCO3= 100/20) and made up of many micro crystals. In chitosan/CaCO3(Mg) composite (mass ratio, chitosan/CaCO3=100/20), the spherical particles were gained and accumulated by the needle particles.4. Organic-inorganic composite was prepared by adding the soluble polymer or sulphate into precursory solution. The CaCO3 particles of in composite were obtained and existed with the form of calcite. The morphology of the CaCO3 particles in composites that introduced PEQ Gel or Na2SO4 into the precursory solution, respectively, had the same points, that the spherical particles were gained and accumulated by the needle particles. And in composites with PVP, so the same thing happened. But in composites with PVP and Mg2+ ions, the shapes of CaCO3 particles were three forms, including efflorescent bundles of needles, sphericity and spindly fiber.