ABSTRACT
The longevity of polymer-based sealant and jointing products, including elastomers, significantly depends on the level of exposure to sunlight and joint movement. These factors are particularly crucial in the application of polymers in construction due to their susceptibility to degradation under environmental conditions. For instance, diurnal cycles of contraction and dilation, arising from daily temperature fluctuations, impose significant stress on sealants and joints, impacting their durability over time. The elastic nature of polymeric sealants enables them to endure these cyclic mechanical loads. Athough there is considerable information on sealant durability obtained from laboratory accelerated aging, there is limited knowledge about the effect of climatic factors using historical and projected weather data on the durability and expected service life of these products. This study employed the Shephard crack growth model to predict the performance of sealants in a Canadian context; the crack growth and time-to-failure of hypothetical silicone sealants were investigated across 564 locations, for which historical climate data were obtained from 1998 to 2017, including gridded reanalysis data for the period of 1836-2015. The historical climate data were classified into four climate categories, and crack growth was estimated based on historical climatic data within the valid range for the Shephard model, revealing that locations in colder climates with lower levels of precipitation typically exhibit higher cumulative crack growth. The impact of climatic variation and environmental stressors on the longevity of sealants in the context of climate change was also investigated using future projected data.
ABSTRACT
With the increasing prevalence of diabetes, the healing of diabetic wounds has become a significant challenge for both healthcare professionals and patients. Recognizing the urgent need for effective solutions, it is crucial to develop suitable scaffolds specifically tailored for diabetic wound healing. In line with this objective, we have developed novel hybrid nanofibrous scaffolds by combining polyvinyl alcohol/chitosan (PVA/CS) and gelatin/poly(ε-caprolactone) (Gel/PCL) polymers through a double-nozzle electrospinning technique. In this study, we investigated the influence of the Gel/PCL blend ratio on the properties of the resulting nanofibers. Three different hybrid scaffold structures were examined: Gel/PCL (80:20)-PVA/CS (80:20), Gel/PCL (50:50)-PVA/CS (80:20), and Gel/PVA (20:80)-PVA/CS (80:20). Our findings demonstrate that the electrospun nanofibers of PVA/CS (80:20)-Gel/PCL (80:20) exhibited optimal mechanical performance, with a contact angle of approximately 54° and a diameter of 183 nm. Considering the crucial role of inhibiting bacterial adhesion in the success of implanted materials, we evaluated the cytocompatibility of the hybrid electrospun nanofibers using mouse fibroblast cells (L-929 cells). The in vitro cytotoxicity results obtained from L-929 fibroblast cell culture on the hybrid scaffolds revealed enhanced cell proliferation and appropriate cell morphology on the PVA/CS (80:20)-Gel/PCL (80:20) sample, indicating its capability to support tissue cell integration. Based on the information obtained from this study, the fabricated hybrid scaffold holds great promise for diabetic ulcer healing. Its optimal mechanical properties, suitable contact angle, and favorable cytocompatibility highlight its potential as a valuable tool in the field of diabetic wound healing. The development of such hybrid scaffolds represents a significant step forward in addressing the challenges associated with diabetic wound care.