This effect is due to the fact that at increased temperature the viscosity of the polymer-solvent solution is reduced. The lower viscosity allows the columbic forces to increase stretching giving finer fibres. Mit-Uppatham et al, (2004) demonstrated that an increase in temperature caused the decrease of solution viscosity, surface tension & conductivity, and resulting polyamide-6 fibre diameter [26]. Increasing temperature also increases evaporation rate, this in conjunction with greater solubility allows for more even stretching and the deposition of more uniform fibre. This was observed by Demir et al, (2002) in their study of parameters affecting the electrospinning of polyurethane fibres [27].