High Strain Rate Response of Sandwich Composites with Nanophased Cores

Abstract

Polyurethane foam materials have been used as core materials in a sandwich construction with S2-Glass/SC-15 facings. The foam material has been manufactured from liquid polymer precursors of polyurethane. The precursors are made of two components; part-A (diphenylmethane diisocyanate) and part-B (polyol). In one set of experiments, part-A was mixed with part-B to manufacture the foam. In another set, TiO 2 nanoparticles have been dispersed in part-A through ultrasonic cavitation technique. The loading of nanoparticles was 3% by weight of the total polymer precursor. The TiO 2 nanoparticles were spherical in shape, and were about 29 nm in diameter. Sonic cavitation was carried out with a vibrasound liquid processor at 20 kHz frequency with a power intensity of about 100 kW/m 2 . The two categories of foams manufactured in this manner were termed as neat and nanophased. Sandwich composites were then fabricated using these two categories of core materials using a co-injection resin transfer molding (CIRTM) technique. Test samples extracted from the panel were subjected to quasi-static as well as high strain rate loadings. Rate of loading varied from 0.002 s −1 to around 1300 s −1 . It has been observed that infusion of nanoparticles had a direct correlation with the cell geometry. The cell dimensions increased by about 46% with particle infusion suggesting that nanoparticles might have worked as catalysts during the foaming process. Correspondingly, enhancement in thermal properties was also noticed especially in the TGA experiments. There was also a significant improvement in mechanical properties due to nanoparticle infusion. Average increase in sandwich strength and energy absorption with nanophased cores was between 40-60% over their neat counterparts. Details of manufacturing and analyses of thermal and mechanical tests are presented in this paper.

Preparation and characterization of colloidal carbon sphere/rigid polyurethane foam composites

“…As the foams had close foam densities and were fabricated in identical closed molds, the PUF/CCS composites with a smaller cell size had to have a thinner cell edge than the neat foam. This was confirmed by the SEM micrographs shown in Figure 7(a–c), which show that the cross‐sectional areas of the cell edges were 914 μm 2 for the neat PUF and 593 and 402 μm 2 for the PUFs with 2.3 and 4.6 wt % concentrations of CCSs, respectively 20…”

Ultrasonication Technique: A Method for Dispersing Nanoclay in Wood Adhesives

“…In this aspect, ultrasonication is an alternative to high-speed mixers and agitator bead mills. Ultrasonication has been used as a technique to disperse nanomaterials in different matrices [26][27][28][29][30][31][32][33].…”

Improving Ballistic Performance of Polyurethane Foam by Nanoparticle Reinforcement

“…The materials used for manufacturing the sandwich composite with nanophased foam are shown in Table 1. Manufacturing procedure of sandwich composites with nanophased core is discussed elaborately in our previous work [11]. However, in brief, nanophased polyurethane foam was fabricated in two steps-the first step was the dispersion of nanoparticles (via sonication) into liquid polyurethane, and the second was the casting of foam.…”

“…As both neat and nanophased foams have similar densities [11] and they are fabricated in identical closed molds, nanophased foam with larger cell size must have thicker cell edge, wall, or faces than those of the neat foam. This is confirmed by SEM micrographs shown in Figure 4 where it is found that cell wall thickness in nanophased foam is 7.4 μm whereas in neat polyurethane foam, it is 3.86 μm.…”

“…The modified foam showed improved mechanical properties both in static and dynamic compression tests. The effect was even more pronounced when this modified foam was used as core materials for sandwich structures [11]. A 2 Journal of Nanotechnology few more attempts have been made to infuse nanoparticles in polyurethane and reported enhancement in chemical and mechanical properties [12][13][14][15][16].…”