  The new method of the mean-field approximation is extended. An approach which
enables to estimate some parameters of the transition from the isotropic state
of hard sticks to the nematic ordering phase is suggested. An technique of the
investigation of the model jointed to the so-called polymer excluded volume
problem is proposed. The critical exponents are estimated. The transition of a
swelling polymer coil to ideal is revealed as the polymerization degree of the
chain increases. The entanglement concentration obtained is in accordance with
experimental data for polymers with flexible chains. The number of monomers
between neighbor entanglements assumes to be the ratio of the stick length to
its diameter. The comparison of the theory with experimental data is made.
