Table 3. Mechanical Properties of HNT Modified Polyurethane/E-Glass
Composites
HNT wt % 0 0.8 1.6 2.4
Note: UCS – Ultimate Compressive Strength; Fs – Flexural strength; Ef – Flexural modulus; ILSS – Inter-laminar shear strength
Vf, % 50 52 55 56
UCS (MPa) 82.6 75.7 61.29 81.28
Fs (MPa) 149.13 158.85 138.32 139.53
Ef (GPa) 9.84 12.60 11.33 10.47
ILSS (MPa) 14.28 26.00 14.36 21.86
Conclusions
The addition of HNT™ in soy-based polyurethane/E-glass composites improves mechanical performance considerably. Three different loadings were studied for HNT, 0.8, 1.6, and 2.4 wt percent. Viscosity of polyurethane was observed at 780 cP for 0.8wt percent HNT, which increased to 1080 cP for 2.4wt percent HNT loading. The VARTM process was used successfully with this low-viscosity resin at room temperature. Low viscosity of nanomodified polyurethane makes it a perfect choice for the low-cost VARTM process. The vacuum planetary centrifugal mixer is an efficient, economical, and a fast method of uniformly dispersing HNT in polyol. For 0.8 wt percent loaded HNT modified composites, flexural strength, flexural modulus, and ILSS were increased by 6 percent, 28 percent, and 82 percent, respectively. ILSS is a measure of fiber/matrix adhesion. This research suggested that fiber/matrix adhesion can be improved by modifying polyurethane with HNT, which in turn improves the mechanical properties. Thus, nanomodified soy-based polyurethane/glass composites manufactured using the VARTM process provide alternatives to traditional glass/polyester and glass/vinyl ester composites. These composites will be more environmental friendly for two reasons: (a) polyurethane doesn’t produce styrene emission thus making workplace safe and (b) the polyol component is made from soybean oil, which is a renewable resource.