Lap Joint Test Essay

2.3. Characterization:
2.3.1. Lap Shear Test: To investigate the adhesive strength of epoxy based adhesives, lap shear test was conducted using aluminum substrate. The lap shear specimen was created using two 102× 25×1.6 mm dimension acid etched aluminum substrates with a 12.7mm overlap area. At the overlap portion adhesives were applied and uniformly compressed and then cured prior to testing. The shear tests of each system were carried out as per ASTM D-1002 with cross head speed of 1.27mm/minute using Universal Testing Machine (UTM), LR-100NK (3382 Instron Instruments Ltd, U.K.).
2.3.2. Scanning Electron Microscopy (SEM):
The fractograpy of the adhesive joints of specimens after lap joint test was studied using Scanning Electron Microscopy

Transmission Electron Microscopy (TEM):
The ultrasonic technique was used to disperse the nanomaterials in the base resin. To investigate the extent of dispersion of CNT and degree of intercalation/exfoliation of nanoclay, Transmission Electron Microscopy (TEM) (JEM 1400, JEOL, Japan) with 120 KeV accelerating voltage at different resolutions was used. The specimen with thickness around 70-90 nm for TEM was prepared by using

The XRD patterns were recorded at angle 2θ (2° to 10°) with a scanning rate of 1°/min.
2.3.5. Differential Scanning Calorimetry (DSC):
To examine the curing behavior of pristine epoxy adhesive and the nanomaterials based adhesives, Differential Scanning Calorimetry (DSC) (Q 20, TA Instruments, USA) was used. The uncured systems about 2-10mg weight were heated from 30°C to 200°C at the dynamic heating rates of 5, 10 and 15°C/min.
2.3.5.1 Curing Kinetics Study: To analyze the curing kinetics of DGEBA/TETA system with or without various nanomaterials, the study of activation energy (Ea) for curing is contributory. In DSC technique, usually the degree of conversion (α) is assumed to be directly proportional to the area under the heat flow curve and can be expressed by Eq. (1): α(t)=(H_p (t))/〖∆H〗_Total where Hp(t) is the partial heat of cure reaction at time t, ΔHTotal is the total heat of cure reaction. The rate of conversion (dα/dt) at a given temperature (T) is generally denoted by Eq. (2):