Making and analysing more recyclable multilayer polymer packaging films

大多数用于食品包装的聚合物薄膜是由非常不同的聚合物或金属薄膜组成的多层叠层，这是因为需要满足和平衡各种性能。不幸的是，这种混合材料极难或不可能回收，降低了聚合物包装的整体可持续性。此外，这些聚合物大多来自不可再生的来源，并且是不可降解的。应对这些挑战的办法包括：(A)生产可通过使用外部化学或物理触发器“按需脱粘”以供回收的层压板，从而使材料层分开；(B)利用可再生资源生产薄膜和层压板，这些材料可在使用寿命结束时降解。这些创新将是减少聚合物废物、实现塑料回收和循环经济的关键。然而，多层聚合物薄膜和其他在化学上具有穿透厚度变化(例如，由于降解或小分子吸收)的聚合物薄膜的表征是具有挑战性的。该项目的主要目标是开发一种新的分析能力-红外光谱椭圆偏振光谱仪(IRSE)-用于化学中具有穿透厚度变化的多层聚合物层压板和聚合物薄膜的原位分析。这种光学技术快速、无损，可用于加热、溶剂或蒸汽暴露的测量单元，允许现场观察固化、干燥、膨胀、降解和分层等动态过程。商业IRSE系统并不广泛使用，该技术也很少应用于聚合物挑战。我们将利用位于曼彻斯特的亨利·罗伊斯研究所可持续材料创新中心内的新IRSE能力来开发这一关键的聚合物创新使能技术。学生将通过IRSE测量模型多层聚合物样品(包括真正的聚合物包装样品和内部制造的薄膜)，并开发必要的分析方法，使用模型样品来表征这些多层叠层。将演示并应用贯穿厚度的化学分析来了解聚合物的固化、干燥、膨胀、降解和分层。结果将与其他技术相关联，包括各种显微镜、差示扫描量热分析(DSC)、动态机械热分析(DMTA)和机械测试。最后，在多层聚合物薄膜和埋层表征方面获得的洞察力和专业知识将应用于初步实验，以开发可响应外部触发并允许层压板分离和回收的多层包装膜的新型粘合层。还将研究这些新型层合板对模拟真实世界使用条件的响应。除了表征工作外，学生还将获得样品制备和新材料合成和配方的“湿化学”实验室工作的实践经验，以及用于薄膜制作的一些实用的聚合物加工。

Most polymer films used in food packaging are multilayer laminates of very different polymers or metal films, due to the wide range of properties which need to be satisfied and balanced. Unfortunately, such mixed materials are extremely difficult or impossible to recycle, reducing the overall sustainability of polymer packaging. In addition, the polymers are mostly made from non-renewable sources and are non-degradable. Approaches to these challenges include: (a) producing laminates that can be separated for recycling by "debonding on demand" with an external chemical or physical trigger, allowing the material layers to be separated; (b) producing films and laminates from renewable sources which can be degraded at end-of-life. Such innovations will be key for decreasing polymer waste and enabling recycling and the circular economy for plastics. However, characterization of multilayer polymer films, and other polymer films which have through-thickness variation in chemistry (e.g. resulting from degradation or small molecule uptake) is challenging. This main objective of this project is to develop a new analysis capability - infrared spectroscopic ellipsometry (IRSE) - for the in-situ analysis of multilayer polymer laminates and polymer films with through-thickness variation in chemistry. This optical technique is fast, non-destructive and can be used with measurement cells for heating, solvent or vapour exposure, allowing dynamic processes such as curing, drying, swelling, degradation and delamination to be observed in-situ. Commercial IRSE systems are not widely available and the technique has been rarely applied to polymer challenges. We will use the new IRSE capability within the Henry Royce Institute Sustainable Materials Innovation Hub at Manchester to develop this key enabling technology for polymer innovation. The student will measure model multilayer polymer samples (including real polymer packaging samples and in-house fabricated films) by IRSE and develop the necessary analytical methods using model samples to characterize these multilayer stacks. Through-thickness chemical profiling will be demonstrated and applied to understanding polymer curing, drying, swelling, degradation and delamination. Results will be correlated to other techniques including various microscopies, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and mechanical testing. Finally, the insight and expertise gained into the characterization of multilayer polymer films and buried layers will be applied in initial experiments towards developing new adhesive layers for multilayer packaging films than can respond to an external trigger and allow the laminate to be separated and recycled. The response of these new laminates to simulated real-world usage conditions will also be investigated. In addition to characterization work, the student will also gain hands-on experience of "wet chemistry" laboratory work for sample preparation and new materials synthesis and formulation, in addition to some practical polymer processing for film fabrication.Suggested EPSRC Research Area: Polymer Materials