The influence of applied silica nanoparticles on a bio-renewable castor oil based polyurethane nanocomposite and its physicochemical properties

Abstract

Novel bio-renewable castor oil based polyurethane (PU)-silica nanocomposite films were prepared using castor oil, 1,6-hexamethylene diisocyanate and dibutyltin dilaurate in tetrahydrofuran at room temperature. ATR-FTIR spectra confirm the formation of polyurethane and the presence of silica nanoparticles in the polyurethane matrix. The increase of Si nanoparticle content shifts the peak position of N-H and C[double bond, length as m-dash]O (both hydrogen and non-hydrogen bonded) groups present in the polyurethane structure. Furthermore, Raman spectra confirmed the urethane-amide interaction present in the polyurethane-silica nanocomposites. (29)Si CP/MAS NMR spectra evidence the formation and the presence of completely condensed SiO2 species in the polyurethane nanocomposite films. The incorporation of silica nanoparticles increases the thermal stability of the above-mentioned polyurethane films, which can be seen from the increase in activation energy (Ea) values of the degradation process. The Ea values at two stages (Tmax1 and Tmax2) of the degradation process are 133, 139 and 157, 166 kJ mol(-1) for PU control and PU-5AMS (5 wt% amine modified silica nanoparticles), respectively. DSC results prove the interfacial interaction present between silica nanoparticles and the polyurethane hard segment, which decreases the melting temperature. Optical transmittance of the polyurethane films decreased with increasing silica content due to the scattering at the interfaces between the silica nanoparticles and polyurethane. It is interesting to note that the presence of silica nanoparticles gives reinforcement to polyurethane film, thereby increasing the storage modulus up to 24% for PU-5AMS. FE-SEM and HR-TEM images confirm the presence of silica nanoparticles in the polyurethane matrix.

Aminopropyl-Silica Hybrid Particles as Supports for Humic Acids Immobilization

“…The co-precursors/TEOS molar ratio was chosen according to the method described by Brambilla et al [28]. The surface modification of the preformed SiO 2 particles was previously performed by other groups [29,30], but our preparation procedure is different from what was previously reported. Thus, Jung et al [29] obtained amino-functionalized silica particles only in ethanol medium and after the re-dispersion of the pristine SiO 2 particles.…”

“…Thus, Jung et al [29] obtained amino-functionalized silica particles only in ethanol medium and after the re-dispersion of the pristine SiO 2 particles. Also, Meera et al [30] prepared castor oil based polyurethane (PU)–silica nanocomposite films by adding amino functionalized silica particles to the polyurethane mixture. Their amino functionalized silica particles were prepared by a method similar to that used by us, but they did not study the effect of the alkyl spacers over the particles ability to immobilize humic acids.…”

Castor oil‐based polyols with gradually increasing functionalities for biopolyurethane synthesis

“…25 Having inherent hydroxyl functionalities in its triglyceride structure castor oil can be easily utilized as polyols in the preparation of PUs without any modification to its original structure. [25][26][27][28][29][30][31][32][33][34] It is also a nonedible and cost-efficient plant oil, making it an ideal alternative to petroleum-based polyols. Moreover, castor oil has additional reactive sites (carbon-carbon double bonds) as well as its hydroxyl allowing further modifications.…”

Rational design of sustainable polyurethanes from castor oil: towards simultaneous reinforcement and toughening

“…The poor mechanical properties hindered their use in structural applications, which is probably responsible for abandonment of castor oil in the modern polyurethane industry. The requirement for sustainable development has triggered renewed interest in fabrication of polyurethanes from castor oil in recent years [20][21][22][23][24][25].…”