Surface Modification Of CaCO₃ Based On Interfacial Design And The Application In The Toughening Of PP And PVC

Polymer toughen by rigid inorganic particles (RIF) avoids the disadvantages of improving the toughness while reducing the rigidity in polymer toughen by elastomer, and this offers a new method to manufacture polymeric composite with higher toughness and higher strength. Based on the interfacial design, the modification of calcium carbonate (CaCO₃) with chemically bonded by macromolecule were studied in this dissertation. The modified CaCO₃ has the core -shell structure, with CaCO₃ as the core and the flexible modifiers with suitable thickness and high compatibility with the matrix resin as the shell. And the application of modified CaCO₃ in toughening poly (vinyl chloride) and polypropylene were researched respectively.In the chapter 2 of this dissertation, the modification of CaCO₃ based on interfacial design and the application in the toughening of PVC were studied. Kinds of modified CaCO₃ with different surface layer were prepared. And their interface characteristics with PVC were studied by the method of contact angle. Compared with the interface characteristics between CaCO₃ and PVC and the mechanics properties of the PVC/CaCO₃ composites, the CaCO₃ modified with TDI . Polyether (R204) and liquid butadiene-acrylonitrile (CTBN) was chosen as the filler which has better effects on improving the toughness of PVC. With the help of infrared spectrum (IR) and thermogravimetry analysis (TG), it proved that the surface of CaCO₃ was bonded chemically by TDK R204 and CTBN successfully and the surface polarity varies from large (inner) to small (outer), so the "core-shell" structure was formed. The mechanics properties of PVC filled with the modified CaCO₃ by means of macromolecule bonded were greatly improved in comparison with those of unmodified CaCO₃ or CaCO₃ modified with coupling agents. The charpy impact strength of the system filled with 30 portions of CaCO₃ modified by macromolecule bonded is 2.5 times of pure PVC. The ESM analysis shows that the conjoint between CaCO₃ particle and the matrix PVC resin is very tight, and the morphology of the fracture surfaces is very rough with slippages and drapes. It means that the PVC/CaCO₃ composites have changed their brittleness to toughness.