| As an important inorganic powder material,nano calcium carbonate is widely used in plastics,rubber,paint,ink and paper making industries.Because the specific surface area and specific surface energy of nano calcium carbonate are large and easy to agglomerate,the surface of nano calcium carbonate is hydrophilic and oleophobic and has poor compatibility with polymer materials.Therefore,it is necessary to modify the surface of nano calcium carbonate to suffice the application in polymer materials.Most of the traditional modification processes use small molecule modifiers such as stearic acid,which cause serious loss in the modification process and poor modification performance.This research has developed a new modification process.The polymer latex is added into the nano calcium carbonate slurry to prepare a polymer composite material with excellent properties.Firstly,styrene and butyl acrylate are used as comonomers,acrylic acid and acrylamide are used as functional monomers,and synthesize a special styrene-acrylic emulsion.Study the effect of process parameters on emulsion synthesis.The results show:When the emulsion polymerization temperature is 85°C and the reaction time is 3.5hours,the ratio of butyl acrylate to styrene is 3/4,the functional monomer acrylamide is1.5%,the amount of acrylic acid is 2%,the emulsion system is stable,and the overall performance is good.The product is tested by FT-IR and TEM.The latex particles exhibited a regular sphere structure of 80-120 nm.The synthetic styrene-acrylic emulsion directly add to the prepared nano calcium carbonate slurry,Through the heating reaction,The surface of nano calcium carbonate particles wrap the polymer molecules.After being centrifuged and dried,a polymer-coated modified nano calcium carbonates are prepared.Study the effects of modification process,modification parameters and addition amount of polymer emulsion on the modification effect of nano calcium carbonate.The results show:When the modification reaction temperature is 85°C,the reaction is carried out for 2 hours,centrifuged at 4000 r/min,and vacuum dried to obtain the modified nano calcium carbonate activation degree of 93%,oil absorption value of 28 g DOP/100 g,and sedimentation volume of 3.1 ml/g.Hydrophobic performance is good.Using TEM,SEM,a particle size distribution analyzer,TG,FT-IR test,The results show:The modified nano calcium carbonate distribute evenly and there is almost no reunion.The polymer emulsion coates evenly on the nano calcium carbonate surface and the coating thickness is about5-15 nm.Infrared shows that the characteristic peaks of the emulsion appear in the nano calcium carbonate with a thermal weight loss of 12.7% and a particle size distribution of80-150 nm.Adding the modified nano calcium carbonate as filler to the polypropylene material,which to prepare a nano calcium carbonate/polypropylene composite material.Comparison of different modification methods,affect the amount of polymer-modified nano calcium carbonate coating,the addition amount of nano calcium carbonate composites to effect the mechanical properties,The results show:When the addition amount is 20%,the amount of polymer coating is 15%.The acrylamide-modified styrene-acrylic emulsion has the best modification effect on nano calcium carbonate,and the mechanical properties of PP added are excellent.Through the SEM,tensile properties test,The results show:The modified nano calcium carbonate disperse evenly in PP.Tensile strength test showed that the tensile strength of the nano-Ca CO3/PP composite modified by a special emulsion reached 37.8MPa.Its mechanical properties are better than small molecule modifiers and unmodified calcium carbonate composites. |
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