A theory was developed for the nonlinear growth of linear chains by in
corporating the chain dynamics into the rate equation. This was achiev
ed by using a modified Boltzmann equation. The chains were first divid
ed into two groups as reacting and unreacting chains in any time inter
val. The contribution of reacting chains to the chain growth was accou
nted by using a time propagator. The nonlinearity in growth introduced
by reacting chains was expressed in velocity space as a kind of enhan
ced diffusion. The space-independent and the space-dependent solutions
of chain growth were obtained by using an almost unchanging quantity,
the ''fractional change of length per collision''. The statistical me
chanics of chain growth was studied and the chain growth distance was
determined.