Conversion of Bamboo into Strong, Waterproof, and Biodegradable Thermosetting Plastic through Cell Wall Structure Directed Manipulation.

Reckoning with the global environmental challenge of plastic pollution, particularly in terms of recycling and biodegradation of thermosetting plastics, sustainable alternatives are imperative. The rapidly growing and eco-friendly material bamboo has great potential as a sustainable resource; however, it lacks the inherent self-bonding and plasticity characteristics found in plastics. This study presents a feasible approach to enhance the plasticity of bamboo by selectively removing part of its lignin and disrupting the crystalline structure of cellulose. Concurrently, this process selectively transforms hydroxyl groups into highly reactive dialdehyde groups to increase the reactivity of bamboo. The resulting activated bamboo units undergo a hot-pressing process to transform them into a type of thermosetting plastic (ABTP). The ABTP is highly moldable, and its color can be precisely regulated by adjusting the lignin content. Additionally, it exhibits exceptional solvent and water resistance, along with notable mechanical properties, including a tensile strength of 50 MPa, flexural strength of 80 MPa, flexural modulus of 5 GPa, and Shore D hardness approaching 90. Furthermore, the bamboo-derived plastic exhibits exceptional reusability and biodegradability, presenting feasible and environmentally friendly alternatives to conventional plastics while harnessing the sustainable development potential of bamboo.

Development of Biodegradable Thermosetting Plastic Using Dialdehyde Pineapple Stem Starch.

Starch extracted from pineapple stem waste underwent an environmentally friendly modification process characterized by low-energy consumption. This process resulted in the creation of dialdehyde pineapple stem starch featuring varying aldehyde contents ranging from 10% to 90%. Leveraging these dialdehyde starches, thermosetting plastics were meticulously developed by incorporating glycerol as a plasticizer. Concurrently, unmodified pineapple stem starch was employed as a control to produce thermoplastic material under identical conditions. The objective of streamlining the processing steps was pursued by adopting a direct hot compression molding technique. This enabled the transformation of starch powders into plastic sheets without the need for water-based gelatinization. Consequently, the dialdehyde starch-based thermosetting plastics exhibited exceptional mechanical properties, boasting a modulus within the range of 1862 MPa to 2000 MPa and a strength of 15 MPa to 42 MPa. Notably, their stretchability remained relatively modest, spanning from 0.8% to 2.4%. Comparatively, these properties significantly outperformed the thermoplastic counterpart derived from unmodified starch. Tailoring the mechanical performance of the thermosetting plastics was achieved by manipulating the glycerol content, ranging from 30% to 50%. Phase morphologies of the thermoset starch unveiled a uniformly distributed microstructure without any observable starch particles. This stood in contrast to the heterogeneous structure exhibited by the thermoplastic derived from unmodified starch. X-ray diffraction patterns indicated the absence of a crystalline structure within the thermosets, likely attributed to the establishment of a crosslinked structure. The resultant network formation in the thermosets directly correlated with enhanced water resistance. Remarkably, the thermosetting starch originating from pineapple stem starch demonstrated continued biodegradability following a soil burial test, albeit at a notably slower rate when compared to its thermoplastic counterpart. These findings hold the potential to pave the way for the utilization of starch-based products, thereby replacing non-biodegradable petroleum-based materials and contributing to the creation of more enduring and sustainable commodities.

Justification of the Use of Composite Metal-Metal-Polymer Parts for Functional Structures.

The additive manufacturing of metal parts takes up an increasing number of areas of mechanical engineering, but it still remains too expensive for mass use. Based on the experience in the production of combined metal-metal-polymer forming parts of molds, a new method for the production of composite parts from a metal shell filled with metal-polymer is proposed. As a basis for the study, strength calculations are given by the finite element method for the details of the exoskeleton and a sample of simplified geometry. Comparison of the strength characteristics of parts made of various materials and their combinations showed high strength characteristics of a composite part made of a metal shell and a metal-polymer filler. The metal-metal polymer composite part is distinguished not only by its high strength but also by a significantly lower cost, due to the reduction in the volume of 3D printing with metal. The problems of obtaining composite structures are also discussed. The main problem is the development of a metal-polymer casting technology. The process of filling a thin-walled shell with a metal-polymer causes difficulty.