Interstellar dust grains can be spun up by radiative torques , and the resulting centrifugal force may be strong enough to disrupt large dust grains .
We examine the effect of this rotational disruption on the evolution of grain size distribution in galaxies .
To this goal , we modify our previous model by assuming that rotational disruption is the major small-grain production mechanism .
We find that rotational disruption can have a large influence on the evolution of grain size distribution in the following two aspects especially for composites and grain mantles ( with tensile strength \sim 10 ^ { 7 } erg cm ^ { -3 } ) .
First , because of the short time-scale of rotational disruption , the small-grain production occurs even in the early phase of galaxy evolution .
Therefore , even though stars produce large grains , the abundance of small grains can be large enough to steepen the extinction curve .
Secondly , rotational disruption is important in determining the maximum grain radius , which regulates the steepness of the extinction curve .
For compact grains with tensile strength \gtrsim 10 ^ { 9 } erg cm ^ { -3 } , the size evolution is significantly affected by rotational disruption only if the radiation field is as strong as ( or the dust temperature is as high as ) expected for starburst galaxies .
For compact grains , rotational disruption predicts that the maximum grain radius becomes less than 0.2 \micron for galaxies with a dust temperature \gtrsim 50 K .