Long-Term Thermo-Kinetic Stability and Predictive Modeling of a Novel Bio-Based Phase Change Material: Stipa ichu Lignocellulosic Fibers Impregnated with Bovine Tallow

Resumen

The transition toward zero-emission building infrastructures requires the integration of high-performance phase change materials (PCMs) that demonstrate exceptional long-term cyclical stability. This research presents the synthesis and rigorous thermo-kinetic evaluation of a novel, shape-stabilized organic biocomposite. Utilizing vacuum-assisted impregnation, refined bovine tallow was successfully encapsulated within the lumen of alkaline-treated Stipa ichu fibers, achieving a substantial 60 wt% PCM loading capacity. The chemically modified lignocellulosic network exhibited robust capillary confinement, severely restricting fluid leakage to below 4.5% under extreme thermal stress (65 °C). To meticulously assess operational longevity, the biocomposite was subjected to an accelerated degradation protocol comprising 1,000 continuous melt-freeze cycles. Differential Scanning Calorimetry (DSC) elucidated a remarkable thermal resilience, with the composite retaining 95.4% of its initial latent heat (decreasing marginally from 145.2 J/g to 138.5 J/g) while maintaining a stable phase-transition temperature at 43.2 °C. Furthermore, Fourier-transform infrared spectroscopy (FTIR) analyses corroborated the system's absolute chemical inertness post-aging, evidenced by the complete absence of oxidative degradation markers such as hydroperoxides. To extrapolate these empirical findings into a practical operational timeframe, a Support Vector Regression (SVR) computational model was deployed. The predictive analytics forecast that the biocomposite will sustain a critical latent heat threshold (>130 J/g) for approximately 2,500 continuous cycles. In the context of the severe diurnal temperature variations characteristic of the Andean highlands, this thermodynamic endurance correlates to a functional service life surpassing 7 years. Consequently, this architected animal fat/Stipa ichu matrix presents a highly viable, ecologically benign alternative for advanced thermal mass regulation in sustainable architectures