- The stress–strain behavior of randomly crosslinked polydimethylsiloxane (PDMS) networks was studied. The small-strain data obtained agreed well with available data on radiation- crosslinked PDMS networks. It was found that both the suppression of junction fluctuation and trapped entanglements have to be considered in order to account for the discrepancy between experimental data and the phantom-network theory. With the addition of a constant trapped entanglement term, Flory's recent network model describes correctly the behavior of our networks under tonsion and compression. The values of the parameters used in fitting the data are within the range suggested by Flory for typical rubber networks. Edwards'“potential pipe” theory did not correlate our data over the entire range of strain variation.