Structural Design And Synthesis Of Hyper-dispersant Agent And It's Application In Plastics Modification

In the field of filled modified plastics, the superfine or nanometer inorganic powders usually were used as a filling materials. But the character of large surface area and surface energy of the particle make the particles assembled with each other. Modified filled plastics not only reduce costs but also improve the properties of plastics matrix composite, so how to solve the particles assembled is major problem now. In the doctoral thesis research, aimed at the current hot spot of the polymer matrix composite materials based on the specifics inorganic fillers and matrix resin natures, designed and synthesized new type of hyper-dispersant agents, and discussed the kinetic of hyper-dispersant agent synthesis. At the same time, used the self-made hyper-dispersant agent coated the inorganic particles, and adopted melt blending and molding method prepared modified polyolefin composite materials, studied the mechanical properties, crystal properties, rheological properties, thermal stability, microstructure and other properties of composite materials.1. Based on the molecular structure design theories, taking the surface properties of superfine CaSO₄, talc and nanoCaCO₃ and basic properties of HDPE, PP and PVC as referenced data, designed the YB and SML series hyper-dispersant agents. And taking silicon oxygen and n-butyl acrylate, as well as styrene, maleic anhydride and 12-alkyl ester used as monomers, AlBN as initiator and 12-thiol as chain transfer agent, by radical solution polymerization method, synthesized the YB and SML series hyper-dispersant agents and explored the dynamics of synthesis, at last token the hyper-dispersant agents structure by FI-IR spectrum and NMR. Based the natures of special filler particles and matrix resins, designed and synthesized the hyper-dispersant agent has not been reported.2. Based on dry modification method, successfully coated the CaSO₄, talc, nanoCaCO₃ inorganic powders used the self-made hyper-dispersant agent, and found the organic groups on the modified powder surface through characterizing the modified powders by FI-IR spectrum and XPS. At the same, the rotation viscosity, velocity and volume of the settlement in liquid paraffin were tested for modified powders. The disperse status in ethanol and thermal analysis of modified powders were measured by SEM and TG respectively.Talc modified by YB hyper-dispersant agent and CaSO₄, nanoCaCO₃ modified by SML hyper-dispersant agent have good impact, the hyper-dispersant agent all have the role of viscosity reduction. The disperse status of particles significantly improved after modified by hyper-dispersant agents in ethanol. Tested major initial thermal decomposition temperature of the CaSO₄,talc, nanoCaCO₃ are 636.8℃,851.1℃and 524.0℃.3. Based on the melt blending method, prepared the SML hyper-dispersant agent modified HDPE/CaSO₄ and PP/talc composite materials modified YB hyper-dispersant, and using capillary rheometer, SEM, XRD, PM, TG etc. tested the mechanical properties, micro-structure, rheological properties, crystal properties and thermal stability properties of HDPE/CaSO₄ and PP/talc composite materials. CaSO₄ particles used as a type of filler in plastic and on the influence of the thermal stability properties of composite materials have not been reported.When the CaSO₄ loading is 30% and SML hyper-dispersant agent dosage is 1.2%, Compared with that of unmodified system, the tensile strength, impact strength, flexural modulus and bending strength of HDPE/CaSO₄ composite materials increased by 12.5%, 12.2%, 37.6% and 15.6% respectively. When the talc loading is 30% and YB hyper-dispersant agent dosage is 1.2%, Compared with that of unmodified system, the tensile strength, impact strength, flexural modulus and bending strength of PP/talc composite materials increased by 15.9%, 8.9%, 10.97% and 11.87% respectively. Using the SEM observed the impact section of HDPE/CaSO₄ and PP/talc composite materials, found that the use of hyper-dispersant agents make the fillers disperse well in the matrix resins, and take the plastic deformation during enduring the foreign forces.HDPE/CaSO₄ and PP/talc composite materials take the performance of non-Newtonian fluid because of the addition of inorganic particles, and with the increasing of inorganic particles, the viscous flow activation energy and non-Newtonian index have increased. At the same loading, the using of SML or YB hyper-dispersant agent can reduce the viscous flow activation energy and non-Newtonian index, this showed that SML and YB hyper-dispersant have the role of viscosity reduction and lower the viscous flow activation energy.The loading of CaSO₄ or talc has no impact on the crystal of its composite materials system, but they all have the role of different complementation nuclear and fine the crystal. The use of SML and YB hyper-dispersant agents can make the inorganic particles disperse well in matrix resins, and further the crystal fine.Non-isothermal crystallization process of HDPE/CaSO₄ and PP/talc composite materials at the same time meet the Avrami equation, Ozawa equation and the MoΦ-t equation. Crystallization kinetics data shows that CaSO₄ and tale in the process of crystallization of HDPE and PP has played a role in different complementation nuclear and a three-dimensional crystal growth process, and the use of SML and YB hyper-dispersant agents make the CaSO₄ and talc engender more significant role during the different complementation nuclear. At low loading of fillers, the crystal activation energy of HDPE/CaSO₄ and PP/talc composite materials is more less than that of pure resins. When the fillers content get to 30%, the crystal activation energy increased, however, the crystal activation energy of composite material show the reduction trend with the increasing dosage of SML or YB hyper-dispersant agents, compared with unmodified system, the dosage of 1.2% hyper-dispersant agent used can reduce 23.2 kJ/mol and 19.44kJ/mol respectively for HDPE/CaSO₄ and PP/talc. CaSO₄ particles has no the ability of change the thermal decomposition process of HDPE/CaSO₄. Thermal decomposition kinetics parameters of composite materials showed that: there has good linear fit when calculated the thermal decomposition activation energy E and pre-lgA based on the Kissinger equation, and when take the Flynn-Wall-Ozawa equation to calculate the E and lgA which increased with the increasing of mass loss rate and the heating rate. The thermal decomposition temperature of polymer materials can be improved by the loading of CaSO₄ and talc. When the loading of CaSO₄ get to 30%, compared with that of pure HDPE, the thermal decomposition activation energy enhance 79.0 kJ.mol^-1 and 88.5 kJ.mol^-1 based on the Kissinger equation and Flynn-Wall-Ozawa equation respectively.Life of the HDPE/CaSO₄ composite materials was obtained based on TOOP formula and the value of thermal decomposition energy, when the loading of CaSO₄ get to 30%, under the 298K, the life of HDPE/CaSO4 is 10⁷ times than that of pure HDPE.4. Based on the molding method, prepared the PVC/nanoCaCO₃ composite materials with SML hyper-dispersant agent modified. Torque rheometer, SEM and TG were used to test the mechanical properties, microstructure, torque and fusion time of various stages and thermal stability properties. About the influence on thermal stability properties and fusion process of hyper-dispersant agent to PVC/nanoCaCO₃ composite materials have not been reported.At the 10% loading of nanoCaCO₃, the tensile strength, impact strength and elongation at fracture of composite material reach the peak. Compared with unmodified filling, the there values of PVC/nanoCaCO₃ composite materials modified by 2% SML hyper-dispersant agent were increased by 12.9%, 15.7% and 25.0% respectively, while the bending modulus of composite materials increased by 27.1% when the nanoCaCO₃ filling get to 20%. And reflect the similar results on the SEM photograph about the impact cross-section.When nanoCaCO₃ content of 15%, compared to the pure PVC, the torque values and fusion time at the various fusion stages were similar. But when the loading of nanoCaCO₃ increased to 30%, compared the pure PVC, the maximum torque from the 38.2 N.m increased to 51.7 N.m, and the fusion time from 162.7 s add to 282.5 s too. Compared the unmodified PVC/nanoCaCO₃ composite materials, the fusion time of the PVC/nanoCaCO₃ composite materials by 2% SML hyper-dispersant modified from 282.5 s decrease to 125.2 s, reduce 125.6%, and the maximum torque values also from 51.7 N.m fall to 31.0 N.m, reduce 66.8%.There is no evident influence nanoCaCO₃ filling to PVC composite materials on its thermal decomposition process. The thermal decomposition temperature of hyper-dispersant agent modified PVC/nanoCaCO₃ is higher than that of pure PVC. Based on the Kissinger equation can calculated that: compared with unmodified filling and pure PVC, the thermal decomposition activation energy of PVC/nanoCaCO₃ modified with 2% SML hyper-dispersant agent increased by 14.56% and 49.86% respectively. While used the Flymm-Wall-Ozawa equation, the results of the two values is 8.41% and 28.20% respectively.