Bulk-degradation of polymers: Model-based analysis of change of molar mass, mass, Young’s modulus, tensile strength and elongation at break

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Understanding the time-dependent degradation behavior of biodegradable polyesters is essential for predicting their long-term mechanical performance in biomedical applications. In this study, we develop an integrated model that links molecular degradation kinetics with macroscopic mechanical property decay, using a series of bulk hydrolytic degradation experiments on tailored polymer blends. Samples were systematically characterized over time for molar mass (M n ), remaining mass (m R ), tensile strength ( σ m a x ), Young’s modulus (E), and elongation at break ( ε b ), enabling simultaneous parameterization of chain-scission kinetics and structure–property relationships. A kinetic model describing the decline in the degree of polymerization was parameterized using non-linear user-defined fitting, allowing accurate prediction of M n decay and mass loss across different blend compositions (95:5, 90:10, and 85:15 of PLLA- co- CL:PDLA) and processing forms (electrospinning and 3D extrusion printing). Mechanical performance was modelled using a linear mechanics-based approach that identifies the ratio between M n and average length of load bearing strands as the determining factor for chain extensibility, ε b , σ m a x and E. The resulting parameters clearly distinguished the behavior of extrusion-printed films versus electrospun meshes and revealed subtle effects of blend ratio on degradation mode and retention of mechanical resilience. The combined kinetic–mechanical model enables quantitative analysis of molecular degradation, mass loss, and mechanical failure criteria from a single unified parameter set. Such a framework could provide a transferable tool for forecasting service lifetimes of degradable polymer devices and rational design of materials with tailored degradation and mechanical resilience profiles. Yet, the analysis also concluded that degradation-induced crystallization is a decisive factor for Young’s modulus and has influence on the tensile strength. Since this crystallization process is not captured by the current model, predictive accuracy for materials exhibiting this phenomenon remains limited unless crystallization kinetics can also be incorporated.