EFFECT OF SIZE ON THE STRENGTH OF POLYMERIC FIBERS

Using a molecular model introduced previously, we study the effects of chain-end segregation on the relationship between strength (sigma) an d diameter (d) in polymeric fibers. For segregated structures with a m onodisperse molecular weight distribution, our results show a scaling law sigma approximately d(-alpha), with alpha in the range [0.4-0.5], in agreement with experimental observation. A weaker dependence is fou nd for polydisperse systems. Further investigation also reveals that m acroscopic cracks have little influence on the fiber strength/diameter relationship, unless the crack width shows a faster than linear incre ase with fiber diameter. Finally, our model results also indicate a ve ry weak dependence of fiber strength on its length, in good agreement with experimental observation. (C) 1995 John Wiley & Sons, Inc.