Variation in the molecular mass distribution (MMD) of straight polymers, with molecular mass (M) of (1.1-2) x 106, upon central, random or terminal chain scisson (CCS, RCS or TCS, respectively) was simulated. The peak in the MMD was shown to shift to a lower M upon CCS or RCS and the randomly cut polymers were more widely distributed than the centrally cut polymers. A bimodal distribution was obtained upon TCS. A parameter 'n1' in a modified Rosin-Rammler plot, where M is substituted for particle size in Rosin-Rammler's equation, stayed at 2.1-2.3 for CCS at the range of large t and it stayed at 1.3-1.7 for RCS. n1 for TCS decreased to zero with increasing t. Application of these simulation results to ball-milling of polyvinylpyrrolidone (PVP) in nitrogen showed that TCS of PVP was accompanied with its RCS. It was also shown that addition of phenothiazine or acridine increased the rate of RCS.