Through the combination of Reynolds equation and Darcy’s law, a mathematical
model was established to calculate the pressure distribution in wedge area, which contributed
to the forecast effect of processing parameters on impregnation degree of the fiber bundle. The
experiments were conducted to verify the capacity of the proposed model with satisfactory
results, which means that the model is effective in predicting the influence of processing
parameters on impregnation. From the mathematical model, it was known that the impregnation
degree of the fiber bundle would be improved by increasing the processing temperature,
number and radius of pins, or decreasing the pulling speed and the center distance of pins,
which provided a possible solution to the difficulty of melt with high viscosity in melt
impregnation and optimization of impregnation processing.
In the manufacture of fibre-reinforced polymer composite materials, the standard technology involves an intermediate product, ‘prepreg’. To make this, the fibres are unwound from a reel in the form of a continuous bundle, or tow, impregnated with the resin matrix and spread out into a thin flat tape. The fibre tow is pulled through a bath of molten resin, passing over a series of bars in zig-zag fashion. The bars serve to locate the tow, control the tension, spread it laterally (and simultaneously reduce its thickness) and squeeze the resin in. The paper presents a simple theory of this spreading and thinning process, giving the spread width w in terms of the cross-section area A of the tow and the lateral offset of the spreader bar H by the simple explicit formula w=(12AH)1/3. Simple experiments to check the theory are reported. The theory also gives an estimate of the thickness, which is more important in the impregnation process, but not readily accessible to direct measurement.