RESUMO
The thermal behavior of commercial chicken, beef, and pork cartilage, were studied using thermal analysis techniques. We use thermogravimetry (TGA) to study their thermal stability between room temperature and 500 °C; differential scanning calorimetry (DSC) in a temperature range between - 50 °C and 300 °C to determine their phase changes associated with endothermic or exothermic processes, and mass spectrometry coupled to TGA to determine the release of elements as they are heated; the results are similar for the three samples. In the thermogravimetric analysis, three different phases were found corresponding to the stages of dehydration (21 °C < T < 100 °C), decomposition (100 °C < T < 300 °C, and degradation (300 °C < T < 500 °C). The DSC study shows two endothermic anomalies corresponding to melting of the aqueous content (-25 °C < T < 25 °C) and evaporation of the aqueous content (27 °C < T < 175 °C), with required enthalpies of 137.30 J/g and 1193 J/g, respectively. Mass spectrometry evidenced the release of molecules such as nitrogen, oxygen, carbon dioxide, and calcium. This study intends to give an approximation to the possible behavior of commercial cartilage that is stored for use in surgery, in no way is it intended to simulate the behavior within the human body, since the biological and physicochemical parameters inside the body are not studied. From the TGA results for different heating rates, we calculated the activation energies required in each of the phases, whose values are 3250,95 J/mol in the dehydration stage, 5130,63 J/mol for decomposition, and 22,677,52 J/mol for degradation. With the activation energies and following the Toops theory (TOOP, 1971) [13], we proceeded to calculate the lifetime in the completion of the three stages or what in thermogravimetric analysis, is known as useful life per stage, finding that a sample of cartilage stored under ambient conditions, after 62 days it loses its initial properties. Which provides an important parameter for the storage of possible synthetic biomaterials with properties similar to cartilage. It is clear that here the useful life or the change of the original properties due to temperature effects is studied, which under the Arrhenius theory is transferred to the kinetic study over time.
RESUMO
Some physical properties of spider silks, including mechanical strength and toughness, have been studied in many laboratories worldwide. Given that this silk is organic in nature, composed of protein, and has similar properties to metal wires or polymers, it has the potential for application in medicine, nanoelectronics, and other related areas. In this study, we worked on spider silk from the Nephila clavipes species collected from the wild and kept it in the nursery of the Autonomous University of the West, Cali, Colombia, to determine its physical, thermal, and mechanical properties, seeking possible applications in the medical and industrial sectors and comparing the material properties of the silk from the species from southwestern Colombia with those of the previously studied species from other regions. The mechanical characterization of the material was performed using a universal testing machine; thermal behavior was captured by a thermogravimetric analysis, differential scanning calorimetry, and mass spectrometry; and structural characterization was performed using diffraction X-rays. The results of the thermal characterization demonstrate that the spider silk loses 10 % of water content at 150 °C with significant changes at 400 °C, while the mechanical characterization indicates that the spider silk is much tougher than Kevlar 49 and Nylon 6 since it is capable of absorbing more energy before rupture.