Preparation Of Ultrafine Calcium Carbonate With Different Morphologies And Study On Toughened Epoxy Resin

Epoxy resin is widely used as one of thermosetting polymers and limitedby its brittleness exhibiting obvious crack growth due to its high degree of chemical crosslinking.Therefore,the toughening of epoxy resin has been an interesting and challenging subject in the academic and industrial fields.So far,the toughening methods of epoxy resin are mainly rubber elastomer toughening,thermoplastic resin toughening,inorganic rigid particle toughening,hyperbranched polymer toughening.Nano calcium carbonate is one of the largest and most widely used inorganic fillers.Therefore,three kinds of calcium carbonate crystals are prepared with special crystal morphology and applied to toughen epoxy resin.(1)Based on the method of organic magnesium,a calcium carbonate micro rod crystal with groove surface morphology was prepared.This method takes the methoxy calcium as calcium source,ethanol magnesium crystal control agent and chitosan as the template,the molar ratio of calcium and magnesium in ethanol control of magnesium ion methoxy in calcium,while in sealed condition through the natural decomposition of ammonium carbonate with carbon dioxide atmosphere,resulting in morphology and length 1?3?m,the radial length of 0.15?0.6 ?m of aragonite whisker(The average length diameter ratio is about 11).(2)Based on the homogeneous precipitation method,the micro calcium carbonate acicular crystal with high aspect ratio was prepared.This method takes the alkoxy of calcium as calcium source,amino compounds containing C and N elements(such as(NH2)2CO,six methyl four ammonium and amino acid etc.)as precipitant,the molar concentration regulation of alkoxy calcium and precipitant ratio,while the seal under high pressure control of temperature and pressure were maintained at 130? and 0.3 MPa,after a certain reaction time by morphology and length of 1?3?m,the radial length of 0.15?0.6?m acicular calcium carbonate whisker(The average length diameter ratio is about 24).(3)Hexagonal CaCO3 nanocrystals with size of 20 nm were prepared by reverse microemulsion.The method of reverse microemulsion composed of cyclohexane(oil phase),ammonium carbonate solution and ammonia(water phase),surfactant and co surfactant composition(HLB value = 3.0?7.0),the alcohol solution of organic calcium as calcium source,through the regulation of W/O system of water phase,the oil phase volume the change and the molar concentration ratio and particle solution and water phase particle solution ratio,thus the synthesis of calcium carbonate crystal hexagonal length less than 25 nm under normal temperature and pressure.(4)Some calcium carbonate and alcohol base groups on the surface of calcium carbonate prepared by methoxy calcium have certain toughening effect on epoxy resin.The results show that the smaller the size of the nano calcium carbonate material,the better the solubility of the resin,the better the performance of the modified epoxy resin,and thus achieve the purpose of toughening.