Effect of Ionizing Radiation on the Chemical Structure and the Physical Properties of Polycaprolactones of Different Molecular Weight

Abstract

Polymers used in the biomedical sector can be exposed to ionizing radiation (X-ray, gamma) in vivo as implants or ex vivo for sterilization purposes (gamma, electron beam). This ionizing radiation can, at certain levels, cause degradation of the polymer. Polycaprolactones (PCL) of different molecular weights were irradiated with electron beam and the changes in their chemical structure and physical properties with the dose were evaluated. Electron beam irradiation produced crosslinking and chain scission in the PCL chain without significant predominance of one mechanism over the other. Minimum dose for gelation decreased with the increase in PCL molecular weight whereas crosslinking efficiency was almost independent of PCL molecular weight. Carboxylic groups, hydroxyl groups and new saturated hydrocarbon species were detected by proton nuclear magnetic resonance (NMR). These species were consistent with a mechanism where chain scission could take place at any bond in the PCL chain with preference in the –COO–CH2– bond. Crosslinking decreased significantly the crystallization temperature of PCL. Tensile properties decreased continuously with the increase in dose. Irradiation with gamma rays produced a faster decay in mechanical properties than electron beam.

Extracted Compounds from Neem Leaves as Antimicrobial Agent on the Physico-Chemical Properties of Seaweed-Based Biopolymer Films

“…The application of gamma irradiation to biodegradable films has been reported to alter the characteristics and subsequently improved the mechanical and barrier properties of the films [6]. It was necessary to irradiate biodegradable films to induce a possible crosslink of the macromolecules as reported in the literature [8][9][10]. It must, however, be noted that the use of gamma irradiation on a packaged product or material has no hazardous effect [11][12][13].…”

Evaluation of electron beam‐induced crosslinking of poly(ε‐caprolactone)—Effect of elevated temperatures

“…that no gel was produced for PCL ( M n : 85,000 g mol −1 ) unless the dose was higher than 200 kGy by γ‐irradiation in the solid state (30–55 °C) in vacuum. Navarro et al . found that a gel content of ~33% was observed at 200 kGy for PCL with a number average molecular mass of 50,000 g mol −1 .…”

“…It should be emphasized that these two basic mechanisms depend on the absorbed dose, polymer structure, the presence of multifunctional additives, gas atmosphere as well as irradiation temperature. Recently, the EB irradiation of PCL in the solid state under different atmospheres (air, oxygen, nitrogen) and vacuum was investigated . Malinowski studied the effect of EB irradiation on the average molecular mass of PCL at room temperature with dose values ranging from 0 to 90 kGy.…”

“…Recently, the EB irradiation of PCL in the solid state under different atmospheres (air, oxygen, nitrogen) and vacuum was investigated. [12][13][14] Malinowski 12 studied the effect of EB irradiation on the average molecular mass of PCL at room temperature with dose values ranging from 0 to 90 kGy. The gel content results showed that the EB irradiated PCL samples completely dissolved in chloroform (CHCl 3 ) and formed no gel fraction.…”

Workflow for highly porous resorbable custom 3D printed scaffolds using medical grade polymer for large volume alveolar bone regeneration

“…In contrast, the application of our workflow system will result in the production of custom scaffolds featuring exact target volumes. These will be created specifically for the patient prior to the day of surgery, and will be supplied to the clinician in a sterile state, after sterilization through gamma irradiation, a suitable technology for PCL scaffold sterilization (Cottam, Hukins, Lee, Hewitt, & Jenkins, ; Navarro, Burillo, Adem, & Marcos‐Fernandez, ; Preem et al, ). These scaffolds can be customized as necessary, potentially allowing for a more rapid surgery and physiologically appropriate mechanical properties, when compared with current treatment methods.…”