Study On The Structures And Properties Of Montmorillonite/Rubber Nanocomposition

Montmorillonite/polymer nanocomposites have attracted great interest in industry and in academia society due to their excellent properties, compared with conventional composites. As montmorillonite layers were dispersed layer by layer in polymer matrix or intercalated by polymer molecules, their nanocomposites often exhibit remarkable improvement in materials properties, and even novel properties. Thus, it is significant importance of theory and application to study the preparation, structure and properties of montmorillonite/polymer nanocomposites.In this paper, montmorillonite/styrene-butadiene rubber nanocomposites were prepared by the solution intercalation method and the melt blending method, respectively. Their structures and mechanical properties were studied. Meanwhile, solid epoxy/montmorillonite nanocomposites were used as a model to study their fire retardancy property. Major ones are showed as follows:1) Conditions were optimized to prepare styrene-butadiene rubber/montmorillonite nanocomposites by the solution intercalation method. Wide angle X-ray characterization and mechanical properties analysis were performed to investigate the effect of montmorillonite content, mixing temperature and mixing time, respectively. The results showed that better intercalation of montmorillonites were abtained with 50℃for 12h. Under the above fixed condition, samples were prepared with different clay content. Their mechanical properties were inferior to those of styrene-butadiene rubber except for the nanocomposites containing the montmorillonite content of 6.0 phr. Above 6.0 phr, the mechanical properties of nanocomposites became worsened quickly with the montmorillonite content. The dynamic mechanical properties were characterized. It was found less impact on its damping properties by the solution method.2) Original montmorillonites and organically-modified montmorillonites (OMM) were utilized to prepare montmorillonite/styrene-butadiene rubber nanocomposites by melt blending method, respectively. Wide angle X-ray characterization and mechanical properties analysis were performed to investigate the effect of original montmorillonites and OMM. It was found that there was no obvious shift of wide angle X-ray peak for OMM during melt-mixing with styrene- butadiene rubber, indicating no change of layer distance of OMM. However, the diffraction peak of the original montmorillonite significantly shifts to small angle, the layer distance increases more than three times. Meanwhile, the mechanical properties and dynamic mechanical properties were characterized. With increase of the amount of original montmorillonites, the tensile strength first increased and then decreased, while the elongation at break has been almost doubly increased, certaim tensile strength is slightly increased and then decreased; dynamic mechanical properties is first increased and then decreased. Clearly, original montmorillonites were better than OMM to reinforce styrene-butadiene rubbe and 3.0 phr of original montmorillonites could be used to obtain clay/rubber nanocomposites with good intercalation effect, mechanical properties and damping properties.3) Montmorillonte/solid epoxy system is used as a model to investigate the migration of nano-particles in the combusting polymer matrix and study the fire retardancy mechanisms. It is found that montmorillonte particles can migrate to the combusting polymer surfaces and form a retardant layer. This retardant layer plays a determined role in improving the fire retardancy of composites through reducing reflex heat, slowing down the pyrolysis rate and keeping the pyrolyzed products from running into the air to some extent. This idea is successfully applied in thermoset fire retardant nanocomposites to pre-form one retardant layer of carbon nanobute, carbon nanofiber or montmorillonites on the outmost surface of nanocomposites.