| Several polymers including high density polyethylene, poly(vinylidene fluoride), and poly(ether imide) were investigated for use in developing synthetic fibres for reinforcement of concrete. Tensile testing was conducted to evaluate the key physical properties of the fibres that affect their concrete reinforcing capabilities such as elastic modulus and tensile strength. These physical properties are dependent upon the fibre's degree of molecular orientation and, in the case of semi-crystalline polymers, the percent crystallinity. The molecular orientations of all phases present in the fibres were determined by wide-angle X-ray diffraction and differential scanning calorimetry was used to find the percent crystallinity. These quantities were used not only to explain differences in tensile properties but also predict whether or not improvements could be obtained with further optimization of processing conditions. The tensile properties were ultimately used to assess the potential of each material for use as concrete reinforcing fibres. |
