Modification of polycaprolactone in the presence of polyfunctional monomers by irradiation and its biodegradability

Crosslinked PCL was achieved by electron beam irradiation in the presence of polyfunctional monomers (PFM). Using the PFM to crosslink PCL reduces the irradiation dosage required for producing gel. The amount of gel formed was determined as a function of both the irradiation dose and PFM concentration. The higher the PFM concentration, the higher is the gel content. However, the amount of gel increases with irradiation dose to reach its maximum at 40 kGy and thereafter, it tends to level off. As the gel content of PCL increases, the tensile strength increases, but the elongation at break decreases. The crosslinked PCL has higher heat resistance compared with the uncrosslinked one. The enzymatic and soil burial degradation of uncrosslinked and crosslinked PCL was investigated. It was found that the biodegradation rate decreased and strongly depended not only on the degree of crosslinking of PCL but also on the degradation reaction conditions. The results obtained indicated that, by introducing crosslinking into PCL, its physical characters such as heat stability and mechanical properties were greatly improved, whilst, its ability to biodegrade was diminished. (C) 2004 Elsevier Ltd. All rights reserved.