Research On New Polyurethane Organic/inorganic Hybrid Materials

Organic/inorganic hybrid materials have drawn substantial interest for theiradvantages in combination of the properties of both organic polymer matrix andinorganic particles. To fully fulfill the potentials of the hybrid, it is vital to study howto combine the properties of the two components, and build adjustable structure andhigh-performance hybrid materials.In present dissertation, a novel polyurethane organic/inorganic hybrid materialscontaining silica were prepared by in situ polymerization. Be different fromthe preparation of conventional polyurethane hybrid materials, in this study,silica was used as an extender agent in the synthesis of hybrid instead of theorganic chain extender agents, which was beneficial to environmental protection.Synthesis mechanism of the hybrid materials was researched. The online FTIRspectra indicated that, with time, the absorption of the-NCO around2200cm^-1wasgradually decreased and the absorption of Si-O-C around1060cm^-1was increased. Itproved that–NCO groups of pre-polymer and-OH groups of P-Silica reacted. Theanalysis of the crosslink density showed that the mechanical properties of thesynthesized hybrid materials were greatly improved than the conventional PU whichsynthesized by using small molecule chain extender. SEM images showed the gooddispersion and compatibility of the silica in the hybrid material.Rubber vulcanization technology was used to study the curing process of theresulted hybrid materials. It was found that the optimal curing temperature and curingtime120℃and Tc90+1min, respectively.The effects of the types of polyols and kinds of silica on the structure andproperties of hybrid materials were disclosed. The structure and morphology of thehybrid materials were studied. FTIR measurements found that the peak of-NCOaround2200cm^-1disappeared and the stretching vibration peak of Si-O-C around1070cm^-1appeared, which certified the reaction between-NCO of prepolymer and–OH of silica. SEM images showed that the dispersion of silica in the hybrid materials was related to the types of silica and polyols. In the hybrid materials, whenPCL1000was used as soft segment and40phr P-Silica was added, the dispersion ofsilica is better than other systems. By changing the types of soft segment, molecularweight of soft segment and filler types, the mechanical properties of hybrid materialswere significantly superior to the neat PU. Tensile strength increased by5times andtear strength by3.5times. TG and DSC showed that thermal stability of the hybridmaterials was also improved. Water contact angle showed that hybrid had differenthydrophilic and hydrophobic. After researching types of soft segments and fillers, wegot that the hybrid materials with PCL1000as soft segment and P-Silica as fillerpossessed the best comprehensive properties. Furthermore, we found that the hybridmaterials owned the best performance while-NCO and-OH molar ratio was2.8:1. Byresearching the content of P-Silica, it was found that the mechanical properties ofthe hybrid material containing40phr P-silica was maximum. Especially, the tearstrength reached107kN/m. TG and DSC results showed that the thermal stability ofthe hybrid materials was improved first with the inclusion of P-silica, and thendecreased with the further increasing P-silica content. However, regardless the contentof P-silica, the thermal stability of the hybrid materials was improved than the neatPU. The surface contact angle tests showed that the angle of the hybrid materialswere first increasing and then decreasing with the addition of P-Silica.Researches on the mechanical properties of PU hybrid materials with differentlignin loadings were conducted. The results showed that the mechanical properties ofthe hybrid materials were optimal with the addition of45phr lignin. The synthesis ofPCL/lignin PU hybrid materials were monitored by the online FTIR spectra. It wasfound that the conversion reached90%at180minutes, and then the reaction sloweddown. TG and DSC results showed that, with the incorporation of45phr lignin, T50%of hybrid materials reached a maximum of349.9℃, and the Tg was0.8℃. Thecontact angle analysis showed that the contact angle of the hybrid materialscontaining40phr lignin got a maximum of117.6°.