A quantitative measure of the degree of fibrillation of short reinforcing fibres

The degree of fibrillation of a reinforcing fibre can be viewed as the extent to which the fibre has partially been split longitudinally into thinner fibrils. Fibrillation provides larger surface area and is advantageous because it improves matrix-to-fibre coupling, oil absorption, thickening characteristics, and softness of the fibre. Fibrillation also allows for low bulk density and assists the mat-making capability of the fibre. A general means for quantifying the degree of fibrillation of a fibre is proposed. Taking the squared ratio of the fibre surface area determined by the BET method to that determined by measuring a sampling of many particles in a scanning electron micrograph, the technique for which is described herein, one has a quantitative, relatively simple method for calculating the degree of fibrillation. Results for calcium sodium metaphosphate fibre, a new inorganic fibre developed by Monsanto [1], milled glass fibre, and wollastonite fibre are reported and compared. Benefits of fibrillation are discussed.