The mechanical properties of paper honeycomb will be different from static situation with the changing of strain rate, which has an influence on the application of paper honeycomb. In this paper, the dynamic mechanical properties of paper honeycomb were discussed and the corresponding mathematic model was built in order to present the stress in different deformation stages and depict the energy absorption properties of honeycomb structure. The strain-rate effect was expressed by Comper-Symonds model. According to the mechanical model, the energy absorption diagram under different strain rates was also built from selecting materials of cushion packaging and optimum design of the packaging. Finally, serious experiments were taken and the result showed a good agreement with theoretical models. The proposed model can be used for practical application of the optimum design and material selection of honeycomb sandwich structure.
This work was designed to determine the mechanical properties and static cushioning performance of polyvinyl alcohol (PVA)/bagasse fibre foam composites with a multiple-factor experiment. Scanning electron microscopy (SEM) analysis and static cushioning tests were performed on the foamed composites and the results were compared with those of commonly used expanded polystyrene (EPS). The results were as follows: the materials had a mainly open cell structure, and bagasse fibre had good compatibility with PVA foam. With increasing PVA content, the mechanical properties of the system improved. The mechanical properties and static cushioning properties of the foam composite almost approached those of EPS. In addition, a small amount of sodium tetraborate obviously regulated the foaming ratio of foamed composites. With increasing sodium tetraborate content, the mechanical properties of foamed composites were enhanced. The yield strength and Young’s modulus of the material prepared by reducing the water content to 80.19 wt% were too high and not suitable for cushioned packaging of light and fragile products.
Gelatin hydrogels are widely used materials that may require surfactants to adjust their solution’s surface tension for cell attachment, surface adsorption enhancement, or foaming. However, gelatin is a highly surface-active polymer, and its concentrated solutions usually do not require surfactants to achieve low surface tension. However, anionic surfactants, such as sodium dodecyl sulfate (SDS), interact strongly with gelatin to form complexes that impact its hydrogels’ rheological properties, influencing processability and functionality. Nevertheless, there is a lack of systematic research on the impact of these complexes on high gelatin content (i.e., high strength) hydrogels’ rheological properties. In this work, the SDS/gelatin ratio-dependent viscoelastic properties (e.g., gel strength, gelation kinetics, and melting/gelling temperature) of high-strength gelatin hydrogels were investigated using rheology and correlated to surface tension, viscometry, FTIR, and UV-Vis spectrophotometry. SDS–gelatin ratio was proved to be an important factor in tailoring the rheological properties of gelatin hydrogels. The gel strength, gelation kinetics, and melting/gelling temperature of the gelatin hydrogels linearly increased with SDS incorporation up to a maximum value, from which they started to decline. The findings of this work have wide applicability in tailoring the properties of gelatin–SDS solutions and hydrogels during their processing.