Modeling changes in the modulus of poly(ε‐caprolactone) due to hydrolysis and plasticization

Abstract

The evolution of the flexural modulus of poly(e-caprolactone), prepared with a tin(II) 2-ethylhexanoate catalyst, was measured in terms of the polymer molecular weight and moisture content. Changes in the polymer molecular weight were observed, but these did not result in a loss of modulus. Fickian diffusion was used to characterize the absorption of moisture into the polymer. The maximum moisture content and moisture diffusivity constant of the polymer were determined to be 0.62% and 2.039 3 10 25 mm 2 /s, respectively. Reductions in the polymer modulus from 0.5 to 0.4 GPa were attributed to water plasticization. An empirical expression for the polymer modulus as a function of immersion time was developed.

Water absorption properties of phosphate glass fiber‐reinforced poly‐ϵ‐caprolactone composites for craniofacial bone repair

“…It should be noted that the calculated coefficients depend strongly on the microstructure of the specimen, which changes between dry and maximum concentration because of fiber leaching. The diffusivity constant for pure PCL composite is almost half that reported by Aitchison et al 15 …”

“…Note that the unreinforced control specimen remained sensibly constant for the duration of the 900-h trial. When time to reach saturation and the maximum moisture recorded for pure PCL sample in this study is compared with that given by Aitchison et al, 15 the moisture content is smaller (0.38% in this study) while time to reach maximum moisture content is longer (Table I). This can be attributed to the specimen size, which is 2.4 times thicker than the one used in this study.…”

Fabrication Effects on Properties of Composites for Medical Applications: 2 - Retention of Composite Mechanical Properties

“…This saturation was sustained for 3 months with no apparent mass loss due to degradation. Since the saturation level for pure PCL sample is 0.62% [10], it appears that values in excess of this are attributed to variations in void and matrix fractions, as shown in Table 2. The water uptake is then related to the void fraction in the sample.…”

“…This may arise from higher void content : thickness ratios. The ISP process is more capable of fully encapsulating the reinforcing fibers due to the low viscosity reaction mixture used [10]. FS involves a high viscosity polymer melt, which is less capable of totally impregnating the fabric reinforcement [10].…”

“…The ISP process is more capable of fully encapsulating the reinforcing fibers due to the low viscosity reaction mixture used [10]. FS involves a high viscosity polymer melt, which is less capable of totally impregnating the fabric reinforcement [10]. The apparently poor interface of the latter samples also prompted study of the fiber-matrix interface (as presented in the following section).…”