The Study Of The Preparation And Property Of Inorganic Polyurethane Nanocomposites

Polyurethane (PU) is one of the most important and versatile class of polymer materials in industry, which has been widely used in adhesives, synthetic leather, construction, automatic applications, etc. Hence, it has received wide attention for its synthesis, morphology, chemical and mechanical properties. PU generally consists of a soft segment which is a high molecular weight macrodiol and a hard segment which is composed of diisocyanate and low molecular weight diol or diamine. Due to the difference in the chemical structure of the soft and hard segment, microphase separation takes easily arising from the thermodynamic incompatibility in PU. The domain morphology in such phase-separated structures achieved by phase separation or phase mixing has a great influence on the PU properties, which has limited its wide engineering usages. To extend the application fields of PU, researches are compelled to search for alternative PU with higher performance.In general, there are two approaches:the first is to change the molecular structure of polyurethane by modification of its basic building blocks. The second is to introduce the inorganic filler into the polyurethane matrix. Nanocomposites attract increasing interests because of their potential of providing novel performances. The tremendous interfacial area in a polymer nanocomposite helps to influence the composites properties to a great extent even at rather low filler loading. However, the homogeneous dispersion of nanoparticles is very difficult to achieve, because nanoparticles with high surface energy tend to easily agglomerate. To break up the agglomerates, studies have been carried out on the approaches of in situ polymerization of monomers in the presence of nanoparticles and other intercalation polymerization techniques.In this paper, a-chlorohydrin phosphate ester and a high molecular weight poly (propylene glycol) phosphate ester (PPG-P) were firstly obtained by polyphosphoric acid (PPA). Secondly, phosphate betaine was obtained by the reaction ofa-chlorohydrin phosphate and tertiary amine.PPG and TDI were used as main materials, nano-CaCO3, nano-SiO2, nano-ZB were used as fillers to prepare PU nanocomposites.In this paper, we prepared PU/CaCO3, PU/SiO2, PU/ZB and WPU/CaCO3 nanocomposites via in-situ polymerization.In polyurethane/CaCO3 nanocomposites experiments, it was found that PPG-P had successfully attached on the surface of nano-CaCO3 and influenced the decomposition of CaCO3. Well-dispersed and long-term stable nano-CaCO3/polyol dispersions were prepared by a mechanochemical approach with the aid of poly (propylene glycol) phosphate ester (PPG-P). Polyurethane (PU)/CaCO3 nanocomposites were prepared by further in situ polymerization with 6wt% nano-CaCO3. The microstructure and dispersion of nano-CaCO3 in the nanocomposites were investigated. It was found that well dispersion was obtained up to 6 wt% of the surface treated CaCO3 loading for PU/CaCO3 nanocomposite. The segmented structures of PU were not interfered by the presence of nano-CaCO3 in these nanocomposites as evidenced by Fourier transform infrared. Compared with the pure PU, a significant improvement in thermal stability was observed with the addtion of 6wt% of the surface treated CaCO3. The experimental results suggested that the properties of nanocomposites were correlated with the dispersion of nano-CaCO3 in PU and the interfacial interactions between nano-CaCO3 and polymer matrix.In polyurethane/SiO2 nanocomposites experiments, it was found that PPG-P had successfully grafted onto the surface of nano-SiO2 and influenced the dispersion and decomposition of nano-SiO2. Then a series of polyurethane (PU) nanocomposites with the blank SiO2 and the surface treated SiO2 have been successfully prepared via in situ polymerization. The surface modification of nano-SiO2, the microstructure and the properties of nanocomposites were investigated by FTIR, SEM, XRD and TGA. The dispersion quality of SiO2 nanoparticles in PU has greatly improved by the addition of PPG-P. The segmented structure of PU has not been affected by the presence of SiO2 in these nanocomposites. The incorporation of the surface treated SiO2 into PU doesn't improve the first decomposition temperature, but does improve the second decomposition temperature, and in the mass rang of 3 wt% to 10 wt%, the thermal stability of polyurethane increases with increasing nano-SiO2 content due to more interaction between nano-SiO2 particles and macromolecular chainsA series of polyurethane/zinc borate nanocomposites were successfully prepared via in situ polymerization. The PPG-P and OA had successfully grafted onto the surface of ZB and the dispersion quality of ZB nanoparticles in PU has greatly improved by the addition of 1% OA. The segmented structure of PU has not been affected by the presence of ZB in these nanocomposites. Moreover, the incorporation of ZB nanoparticles modified with OA greatly improved the thermal property of PU without disrupting the intrinsic structure of PU, in the range of 1%-4%, the proper amount of OAZB incorporating into PU is 2%.A series of WPU/CaCO3 nanocomposites have been successfully prepared via in situ polymerization. OA has greatly improved the surface characteristics of nanoparticles, from hydrophilic to hydrophobic. SEM examination of the fractured surfaces of nanocomposites showed that OA-CaCO3 achieved well dispersion in WPU matrix. FTIR analysis suggested no major changes in the chemical structure of WPU in the presence of 2 wt% CaCO3. Thermal stability of WPU measured by TGA was greatly improved with the addition of OA-CaCO3. Meanwhile, the mechanical properties of the nanocomposites, examined by tensile tests, showed higher tensile strength than that of the pure WPU, especially incorporation of OA-CaCO3.This paper also investigated the modification of nano-filler by PPG-P and proposed a simple model for the dispersion of nano-filler in PU matrix with the modification of PPG-P. The long alkyl chain of PPG-P is the same as PU matrix', thus, nanoparticles modified with it can exhibit good dispersion and compatibility with PU matrix. The process of preparing phosphate ester is simple and the cost is low, moreover, the source of inorganic filler used is wide, easily to processing and the cost is low, thus, it is useful for the development of PU industry.