Statistical properties of interparticle/void distance for amorphous plastics toughening

Statistical properties of interparticle/void distance (ID) for various particle/void and dispersion types are studied in relation with toughening of plastics using computer-generated three-dimensional models. Particle/ void size groups adopted were either of constant diameter or of log-normal distribution. Particles/voids were dispersed at uniform-random or flocculated with multiple clusters. It was found that IDs are (a) of approximately Gaussian distribution for particles/voids of either a constant diameter or a log-normal distribution, when they are dispersed at uniform-random, but (b) not of Gaussian distribution for particle/void sizes of bimodal log-normal distribution, nor for flocculated log-normal distribution of particles/voids dispersed with multiple clusters. It was also found that the degree of ID uniformity for a single group of log-normally sized particles/voids is not sensitive to standard deviation of particle/void size. Mixing effect on ID properties using two groups of log-normally distributed particles/voids with similar mean particle/void diameters was simulated. It was found that, when a significant amount (36 vol %) of particles/voids of a small mean and standard deviation of ID was mixed with a group of particles/voids of a large mean and standard deviation of ID, mean and standard deviation of ID for the mixture were not substantially lower than those of the group of particles/voids of the large mean and standard deviation of ID. It was also found that the degree of ID uniformity for the mixture of the two groups was lower than those of individual groups, indicating that the mixing has deleterious effect on toughening. (c) 2006 Wiley Periodicals, Inc.