Effect of nano-clay on mechanical and thermal stability of jute composite for structural applications

Abstract

Due to enhanced mechanical strength, superior flame-resistance, decreased gas permeability, montmorillonite nano-clay has been introduced to the jute-polyester resin composite materials for structural application. Long fiber Bangla special tossa jute is being used as reinforcement materials along with 0%, 1%, 3% and 5% addition of nano-clay within the matrix-fiber mixture. These hand lay-up processed 32 cm×32 cm×3 mm plates are used to make samples for tensile test (115 mm × 19.42 mm× 3 mm) and flexural test (125 mm x12.7 mm x3 mm) and impact test (55 mm x10 mm x 10 mm) as per ASTM standards. Yield strengths, percentage of elongation, modulus of elasticity and fracture strength have been calculated from the tensile test for 0%, 1%, 3% and 5% nano-clay filled composites respectively under two different strain rates (0.5 mm/min and 0.8 mm/min). Stress- strain superimposed curves shows clearly that 1% nano-clay filled composite possesses superior mechanical properties in terms of yield strength (3.6 MPa, 0.5 mm/min) and fracture strength (22.39 MPa, 0.5 mm/min) due to optimum density and homogeneous mixture of the added clay. It is interesting to note that 0%, 3% and 5% filled nano-clay filled composites show not much difference in terms of yield strength even-though breaking strength for 3% nano-clay filled composite shows higher value. Effect of temperature and high humidity were evaluated for this nano-clay filled composite through the hydrothermal test for 15 days in the environmental chamber. Environmental degradation was not remarkable due to the exposure of the temperature 80oC and 95% RH for this time period. Thermal behaviours of this jute composite were studied via dynamic mechanical analysis, thermogravimetric analysis and differential scanning calorimetry. The doped hand lay-up processed plates are used to make samples for dynamic mechanical analysis (50 mm × 12.7 mm × 3 mm) and thermogravimetry (6.75mg to 6.85mg) testing as per ASTM standards. Temperature induced weight loss due to Thermal decomposition were measured and char residue were calculated up to 1000ºC where 5% added nano clay samples showed better thermal stability. Viscoelastic properties through storage modulous and loss modulus showed better stability with 1% nanoclay added composite in dynamic mechanical analysis. Moisture and temperature did not affect the tested samples significantly in diminutive exposure for 1% nano clay added samples even though there is a loss of storage modulus of 12 to 30% for 3% and 5% nanoclay added samples, respectively. Further, fractographic evolution for the raw jute is performed by Scanning electron microscopy and field emission scanning electron microscope which shows the continuous unbroken jute fiber cellulose and tress of nano clay. Fractured jute fiber void and nano particles were identified in the fractrographic analysis. It is evident from this investigation composite up to 1wt% both for mechanical and thermal performance. No advantage is observed in terms of mechanical and thermal properties beyond this optimum limit of 1wt%.