Crosslinking of polycaprolactone in the pre‐gelation region

Polycaprolactone (PCL) crosslinked below the gel point either with peroxide or by exposure to ionizing radiation was compared by Theological studies. As a result of peroxide crosslinking, PCL increases in viscosity and shear rate dependence and exhibits increased dynamic moduli that converge at higher frequencies. The analysis of gases evolved from γ‐irradiated PCL shows that the yield of hydrogen (G = 0.39) approximates the sum of the yields of carbon monoxide (G = 0.19) and carbon dioxide (G = 0.21). It is inferred that equal amounts of crosslinking and scission result from ionizing irradiation. As a result, PCL is converted by irradiation to a densely branched system. Steady shear viscosities do not depend strongly on dose and overlap at higher shear rates. Similarly, dynamic moduli, especially G″, become less sensitive to dose.