Research Of Unsaturated Polyester Polyurethane Nanocomposites

As one kind of unsaturated resin, Unsaturated polyester polyurethane (UPPU) has been applied in all fields and every walk of life. However, due to its hard and brittle property, poor impact resistance, abrasion resistance and other poor performance after curing, greatly limited the application in production practice. Using nanometer materials to enhance UPPU modification is an effective way to improve material performance. Now, attapulgite (AT) becomes a valuable candidate for modification because of its high surface energy and surface activity, also with its special physical, chemical properties and unique process performance. Just because of its high length-diameter ratio, good surface activity and a large number of hydroxyl groups, nano AT may easily reunite in the polymer matrix. In order to improve the dispersion ability, interface binding force between inorganic nanoparticles and unsaturated polyester polyurethane at the same time, the AT usually need to treat its surface.In this study, we choose UPPU as matrix resin, the coupling agent KH-550, KH-560, KH-570and the activity of synthesis of coupling agent as modifying agents to change AT from hydrophilic to hydrophobic. Then a series of UPPU/AT nanocomposites with good stability were prepared by chemical grafting method, which pledged a everlasting chemical attachment between the two incompatible objects. The properties of composite materials such as chemical structure, surface morphology, thermal stability and mechanical properties were investigated by XRD, FT-IR, TGA, SEM and mechanics performance testing.After coupling agent treatment, the AT spread evenly. The results of FT-IR showed that the coupling agent functional groups occurred successfully, indicated that the coupling agent may grafted successfully onto AT. The SEM results showed that after ultrasonic treatment and modifying with coupling agent, the nano AT existed just as the way of small crystal rod with beam, the single nano AT reached a length of1microns.After coupling agent modification and ultrasonic treatment, AT existed in tiny crystal bar beam, a single nano AT rod length of at about1microns.The SEM photos with different content of modified nano AT composites showed that when the content of modified AT was1.5%(wt), the cross section of UPPU is straight, it told us its fracture mode was brittle fracture, and almost no reunion phenomenon of AT appeared and uniformly dispersed in the polyurethane matrix. When adding2.5%modified nano AT, the aggregated phenomenon would happen in the resin matrix, which had a great influence on its section morphology. When continued to add nano AT, reunion phenomenon was more serious.Because of the using of coupling agent, the lipophilicity of nano AT had greatly improved. When it was added into UPPU, TGA results showed that the thermal stability of composite materials had gained, this mainly because of the AT is a kind of inorganic rigid particles, it can enhance the thermal stability of polymer.The XRD patterns told us that the coupling agent only grafted in the surface of AT, and the nanocomposites samples are typical of amorphous materials. The UPPU before and after adding modified AT showed similar XRD characteristic peaks, and after adding modified AT didn’t destroy the type of UPPU itself.This study told us that KH-560was the best modifier. When the addition amount of AT was1.5%, almost no reunion phenomenon of AT was appeared and uniformly dispersed in the polyurethane matrix. Compared with pure UPPU, the tensile strength and bending strength of composite materials increased by89%and166.7%respectively. When the addition amount was2.5%, its thermal stability was enhanced, its decomposition temperature had risen about52℃, but nanoparticles had reunion phenomenon, also with the decrease of mechanical properties.