Optimisation of low carbon Biodegradable flexible films from waste feedstocks for high-speed processing into single use flexible packaging

联合利华的可回收软塑料包装的很大一部分没有被收集，有效地分类和回收，最终被填埋或泄漏到环境中。在基础设施不到位的地区，这个问题更为严重。联合利华在战略上优先考虑软包装的创新，例如一次性小袋，因为这些产品本身就很难回收，并且是一个特别紧迫的环境挑战。联合利华产品的软包装每年消耗近20万吨塑料。联合利华开发零净生物降解软包装解决方案的关键材料之一是聚羟基烷酸酯（PHA）。PHA是由细菌从废物原料中产生的聚酯，可以像塑料一样加工和密封，并且在海洋和土壤环境中可生物降解。与目前用于柔性小袋的塑料相比，PHA的一个缺点是其差的防潮性能。联合利华一直致力于通过开发PHA复合膜、在PHA基质中分散填料（商业敏感）来改善PHA膜（特定等级是商业敏感的）的阻隔性能。这种复合方法导致膜具有改善的阻隔性能，但降低了机械性能，使得它们不适合转化成小袋。为了与当前的小袋制造和填充线兼容，PHA复合膜应满足关键的机械性能要求。该项目的目标是优化PHA复合薄膜，使其与现有的供应链和制造工艺兼容，而不影响其包装性能。该项目通过使用低碳可生物降解材料的复合材料和加工材料方法进行创新：a）ICL将不同的PHA和可生物降解聚合物嵌入PHA填料基质中，以提高薄膜的柔韧性; B）将生物基增塑剂添加到复合材料中，以降低薄膜的脆性。塑性在包装膜的高速转化的工艺放大中是重要的。与a）和B）平行，作为实验设计的一部分，将改变填料的加载分数以同时优化阻隔和机械性能。c）曼彻斯特罗伊斯中心将在ICL开发的关键薄膜配方上探索纳米纤维纺丝，作为诱导晶体排列和双轴拉伸薄膜的途径，预计这些薄膜将具有更高的机械性能。柔性复合薄膜的拉伸性能、耐腐蚀性、防潮和阻气性以及它们的热机械性能将被表征和优化。生物可降解复合薄膜的结构-性能-加工关系将被量化，从而确定工艺放大的最佳配方。使用的具体设施是扫描电子显微镜（SEM），原子力显微镜（AFM）和广角X射线散射（WAXS），以研究复合膜的（断裂）形态和结晶度，以及不同聚合物之间的相互作用，以允许工程更好地表现膜。熔体流变仪、吹膜挤出机和开发性纳米纤维纺丝也将用于将制剂加工成膜。纳米纤维纺丝将被探索作为一种途径，以诱导晶体取向和双轴拉伸膜，预计具有更高的机械性能，可以定制。先进的纳米纤维到设备套件也将用于生产规模扩大，机械评估套件将用于研究薄膜，纤维和固结纤维的热机械性能，SEM设施将用于研究薄膜，纤维和固结纤维的形态。

A big part of Unilever's recyclable flexible plastic packaging is not being collected, efficiently sorted and recycled, ending up in landfill or leaking into the environment. This problem is more severe in geographies where infrastructure is not in place. Unilever has strategically prioritised the innovation of flexible packaging, such as single-use sachets, because these are inherently difficult to recycle and represent a particularly urgent environmental challenge. Flexible packaging for Unilever products makes up nearly a footprint of 200,000 tonnes of plastic annually. One of Unilever's key materials of choice for the development of net-zero biodegradable flexible packaging solutions is polyhydroxyalkanoates (PHAs). PHAs are polyesters produced by bacteria from waste feedstocks, can be processed and sealed like plastics and are biodegradable in marine and soil environments. One disadvantage of PHAs compared to current plastics used in flexible sachets is their poor moisture barrier performance. Unilever has been working on improving the barrier properties of PHA films (the specific grade is commercially sensitive) by developing PHA composite films, dispersing fillers (commercially sensitive) within the PHA matrix. This composite approach resulted in films with improved barrier performance, but decreased mechanical performance, rendering them not suitable for conversion into sachets. In order to be compatible with current sachet manufacturing and filling lines, PHA composite films should meet key mechanical performance requirements. The objective of this project is to optimise PHA composite films to make them compatible with existing supply chain and manufacturing processes without compromising their packaging performance. The project innovates by using a composite and processing materials approach using low-carbon biodegradable materials: a) ICL will embed different PHAs and biodegradable polymers within the PHA-filler matrix to improve film flexibility; b) Biobased plasticisers will be added into the composite to reduce film brittleness. Plasticity is important in process scale up for high-speed conversion of packaging films. In parallel to a) and b), as part of the experimental design, the loading fraction of the fillers will be varied to optimise barrier and mechanical performance simultaneously. c) Nanofibre spinning will be explored at the Manchester Royce Hub on the key film formulations developed at ICL as a route to induce crystal alignment and biaxially stretched films which are expected to have higher mechanical properties. The tensile properties, fracture-resistance, moisture and gas barrier properties of the flexible composite films, as well as their thermomechanical properties will be characterised and optimised.The structure-property-processing relationship of the biodegradable composite films will be quantified, allowing for the optimum formulations for process scale up to be identified. The specific facilities to be used are Scanning electron microscopy (SEM), Atomic force microscopy (AFM) and Wide-angle X-ray scattering (WAXS) to study the (fracture) morphology and crystallinity of the composite films, as well as the interaction between the different polymers to allow for the engineering of better performing films. The melt rheometer, blown film extruder and developmental nanofibres spinning will also be used to process formulations into films. Nanofibre spinning will be explored as a route to induce crystal alignment and biaxially stretched films which are expected to have higher mechanical properties and can be tailored. The advanced nanofibres to devices suite will also be used for production scale up, the Mechanical evaluation suite will be used to study the thermomechanical properties of the films, fibres and consolidated fibres, and the SEM facilities will be used to study the morphology of the films, fibres and consolidated fibres.