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The lattice thermal conductivity (K) of amorphous polymer at low temperatures has been analyzed by expressing its total lattice thermal conductivity as a sum of the three contributions as K=KBE +KEM+KAP, Where KBE is the contribution due to those phonons is can interact with crystal boundaries, KEM is due to those phonons which have frequencies less than the plateau frequency (wpt) and KAP is due to those phonons which have frequencies larger that (wpt). the study had been made for polymethyl mathacrylat in the temperature range 0.1- 4K within the frame work of the expression proposed by Saleh et al. which has base on Walton’s theory. A very good agreement has been obtained between experiential and calculated values of K at low temperatures. It has also been found that at low temperatures, the total K of a non crystalline is mainly due the contribution KEM which is due to empty spaces.

- Prakash Dubey *