Role of sequence of feeding on the properties of polyurethane nanocomposite containing halloysite nanotubes

Abstract

Polyurethane/Halloysite Nantubes nanocomposites containing 1 wt.% nanoparticles were prepared using in situ polymerization method with different mixing sequences. Various experiments have been performed in order to evaluate the effect of nanoparticle dispersion and the different orders of mixing of the samples on the mechanical properties and morphology of nanocomposites. The results obtained from the ATR-FTIR test demonstrated that the presence of nanoparticles led to an increase in phase separation, and the sample with the best nanoparticle dispersion has shown more phase separation than the other samples. Furthermore, the results of the Differential scanning calorimetry (DSC) also confirmed more phase separation and the crystallinity of the samples in the presence of nanoparticles. Scanning electron microscope (SEM) images were utilized in order to investigate the dispersion of nanoparticles in polyurethane matrix and to examine surface fracture of the samples. Moreover, differential mechanical thermal analysis (DMTA) revealed that the presence of nanoparticles has altered the glass transition temperature of polymers, and there are physical and chemical interaction and hydrogen bonding between nanoparticles and hard and soft polyurethane segments. In addition, in the presence of nanoparticles the damping of the samples was reduced compared to the neat sample. Change in behavior from liquid like to solid like in the range of low angular frequencies was observed which is in agreement with the formation of a network structure that can be broken even at low shear rates. In the second step, kinetics of the phase separation process of thermoplastic polyurethane and nanocomposites was studied by rheological experiments. The results showed that the kinetics of phase separation process of thermoplastic polyurethane is similar to that of the crystallization process. Phase separation kinetics of neat samples and nanocomposite have been studied. The presence of nanoparticles by nucleation mechanism increased the rate of the phase separation.

The Green Approach to the Synthesis of Bio-Based Thermoplastic Polyurethane Elastomers with Partially Bio-Based Hard Blocks

“…The degree of phase separation (DPS) was determined using the equation: DPS = R/(R + 1). According to the literature, with R increasing, the degree of phase separation in polyurethanes increase [ 40 ]. It was observed that the degree of phase separation of obtained bio-TPU depends on the content of the hard segment, and the same, on the amount of bio-based diisocyanate in the structure.…”

Effect of Liquid Glass-Modified Lignin Waste on the Flammability Properties of Biopolyurethane Foam Composites

“…These results are shown in Figure 2 and summarised in Table 2 . The addition of up to 7.5 wt.% unmodified LigW particles to bioPUR foam shifted the glass transition temperature to higher temperatures due to the constraints of polymer chains [ 34 ]. The maximum increase in T g can be observed for 5 wt.% LigW-modified bioPUR foam composites ( Figure 2 a), while further addition of LigW particles reduced T g to 140 °C, which is 5 °C lower compared to the control bioPUR foam due to the easier movement of the soft segments in the 10 wt.% LigW.…”

Physicochemical characteristics of bio‐based thermoplastic polyurethane/graphene nanocomposite for piezoresistive strain sensor

“…The nanocomposite did not show any aggregation of graphene suggesting homogenous dispersion within the matrix. [ 38–40 ] However, TPU‐2.0 showed some bright spots on the surface, which could be graphene nanoplatelets either dispersed or aggregated nanoplatelets. From the EDS analysis, upon increasing the graphene loading the carbon content and oxygen content increased.…”