Kinetics Study Of Compatibilization Blending Interfacial Reaction And 2-Hydroxy-1, 4-naphthoquinone Redox Reaction

1. Compatibilization of polymer blends provides an efficient way to producematerials with desirable properties. We studied the interfacial reaction kinetics.Firstly, rheometry has been used to monitor the interfacial reaction of SMA/PA andPS/PA6. The complex viscosity (η*) for PS/PA6 blend almost does not changewith time. While the complex viscosity (η*) of SMA/PA increased rapidly withreaction time, which can be divided into three stages. In the initiate stages, equalopportunities for the two reactants lead to a second-order reaction, which iscontrolled by reaction rate. After a short time, the reaction is likely to becomefirst-order because of shortage of NH2 groups in PA6 layer and there is aconversion of second-order and first-order reaction. When the in situ formedcopolymers are sufficient to inhibit the reaction and there is a reaction depletionlayer, the time of building depletion layer is relation to functional group reactivityand concentration. In the late stage, if the two reactants can again meet in theinterface and copolymers still can be formed, and complex viscosity (η*) againincreased slowly with reaction time. For the SMA/PA6 system, second orderreaction is only in the initial stage which is controlled by reaction rate. Later thereaction is likely to be first order and diffusion of PA's chains controlled thereaction process. The miscibility between two polymers can be evaluated through the interfacialthickness. When two polymer films are put together and are heated above theirglass transition temperature, a broad interface will develop with time in misciblesystems, whereas the formation of a thin interface is characteristic of immisciblesystems. The interfacial thickness of PS/PA6 stayed very thin, indicating the strongimmiscibility between PS and PA6. However, the interfacial reaction betweenSMA and PA6 produces in situ copolymers in different ways, the interfacialthickness increased with reaction time and reached constant as thick as 40 nm at 30吉林大学硕士论文min, which was large enough to exceed the coil size of the copolymer produced atthe interface. Thickness of SMA and interface with reaction time proved anasymmetry interface, which more deeply develop into SMA phase. However,the interfacial thickness increased with time in the early stage then obtain constant,there no increasing with time again, which indicated that interfacial area canincrease when interfacial thickness become constant by building undulated andlamellar interface or formation of micelle in SMA bulk. Meanwhile, the results ofinterfacial morphology proved interfacial roughness increased with reaction time inthe system of SMA/PA6. 2. 2-Hydroxy-1, 4-naphthoquinone (HNQ), a natural compound, withal calledas orange 6, was successfully catalytic synthesis form 1- and 2-naphthol overmetalloporphyrin catalysts by hydrogen peroxide with high selectivity. Researchresults reveal the fine reversible redox properties of HNQ. In the visible lightrange, HNQ exhibits a strong absorbance at λmax = 452nm, while other coexistentsubstances, including 1, 2, 4-trihydroxy naphthalene (THN), the reducing state ofHNQ, hydrogen peroxide and sin dichloride, as oxidant and reductant, display noabsorbance. Therefore a in situ kinetic determination method is established basedon HNQ's unique absorbent property. The rate equations and activation energies forHNQ-THN mutual conversion are determined by change the redox conditions.Cycle volt-ampere method shows that HNQ-THN mutual conversion is a twoelectron quasi-reversible processes. The redox potencial is calculated for theselection both of oxidant and reductant.