Sustainable Materials for Balloons

目前，需要开发新的高性能材料，这些材料可以从废物和可再生资源中获得，具有低碳排放，以减少我们的工业对环境的影响和我们对化石燃料的依赖，并实现可持续增长。可以在废纸、建筑木材和农林残留物中发现的废弃纤维素是最丰富的天然生物聚合物，也是实现这一目标的最有前途的原料候选者。由于其理想的性能，如高强度，高刚度，低热膨胀，生物降解性，导电性和可调表面，它被广泛应用于造纸，纺织和高性能包装和薄膜等行业。此外，由于其多维结构，可以在形态和原纤尺寸方面转化纤维素，从而允许进一步改善母体纤维素的物理化学性质。纤维素也是容易生物降解的，并且更高强度的纤维素材料作为生物降解包装是令人感兴趣的。纳米纤维素材料或纳米晶体纤维素（NCC）由一维小于100 nm的纤维素形成。当与传统增强材料相比时，NCC具有高纵横比、较低密度、较高拉伸强度和相似的杨氏模量（Moon等人，JOM，2016，68（9），2383-2394）。这些都是生产填料、复合材料、薄膜、水凝胶和乳液的重要特性，用于包装、药物输送、传感器和电子设备，以及在纳米级时利用纤维素附加功能的新兴行业。目前在工业规模上获得纤维素纸浆的最普遍的方法是硫酸盐法制浆和漂白，但这些方法污染严重，需要用更环保的替代品取代。在该项目中，将使用帝国开发的环境友好型工艺-Ionosolv工艺，然后使用基于过氧化氢的无氯漂白，从废木材中生产净捐助国。Ionosolv工艺可以使用低成本离子液体分离木质纤维素生物质的3种主要成分--纤维素、木质素和半纤维素。这从各种各样的原料中产生富含纤维素的纸浆，包括不与粮食生产竞争的专用能源作物、农业残留物和废木材（Abouelelea等人，ACS Sustainable Chemistry & Engineering 2020（8），14441）。这种方法将使我们能够以更直接的方式获得净捐助国，比目前的进程使用更少的步骤。这将使我们能够将低价值材料转化为航空航天、医疗和计算机行业市场的专业产品。作为该项目的最后一步，获得的纳米晶纤维素可以在可持续的、可生物降解的复合材料中进行测试，或者（如果是纤维状的）压成薄膜，用作可生物降解的包装材料。

Currently, there is a need to develop new high-performance materials that can be obtained from waste and renewable sources with low carbon emissions to reduce the environmental impact of our industries and our dependence on fossil fuels and to achieve sustainable growth. Waste cellulose, which can be found in waste paper, construction wood and agricultural and forestry residues, is the most abundant natural biopolymer and the most promising feedstock candidate to achieve this goal. Thanks to its ideal properties such as high strength, high stiffness, low thermal expansion, biodegradability, conductivity and tuneable surface, it is employed in a wide range of industries such as paper, textiles and high-performance packaging and films. Furthermore, due to its multi-dimensional structure, it is possible to transform cellulose in terms of morphology and fibril size, allowing for further improvement on the physico-chemical properties of parent cellulose. Cellulose is also readily biodegradable, and higher-strength cellulosic materials are of interest as biodegradable packaging. Nanocellulosic materials or nanocrystalline cellulose (NCC) are formed from cellulose with one dimension under 100nm.3 NCCs have high aspect ratio, lower density, higher tensile strength and similar Young's Modulus when compared to traditional reinforcement materials (Moon et al., JOM, 2016, 68(9), 2383-2394). These are important characteristics in the production of fillers, composites, films, hydrogels and emulsions for applications in packaging, drug delivery, sensors and electronic devices, emerging industries that utilise the added functionalities of cellulose when at a nanoscale. The most widespread current methods to obtain cellulosic pulps at industrial scale are kraft pulping and bleaching, but these are highly polluting and need to be replaced by more environmentally friendly alternatives. In this project, NCCs will be produced from waste wood using an environmentally friendly process developed at imperial, the Ionosolv process, followed by chlorine-free bleaching based on hydrogen peroxide. The Ionosolv process allows the separation of the 3 main components of lignocellulosic biomass -cellulose, lignin and hemicellulose- employing low cost ionic liquids. This yields a celluloserich pulp from a wide variety of feedstocks, including dedicated energy crops that don't compete with food production, agricultural residues and waste wood (Abouelelea et al, ACS Sustainable Chemistry & Engineering 2020 (8), 14441). This method will allow us to obtain NCCs in a more straightforward way, using fewer steps than the current processes. This will allow us to convert a low value material into specialised products with markets in the aerospace, medical and computer industries. As a final step in the project, the obtained nanocrystalline cellulose could be tested in sustainable, biodegradable composites or (if fibrous) pressed into films for use as biodegradable packaging material.