Improvement of melt strength and crystallization kinetics of biopolyesters by reactive extrusion

生物塑料包括可堆肥的和/或由可再生资源制成的热塑性聚合物，例如聚（乳酸）（PLA）、聚-3-（羟基链烷酸酯）（PHA）和淀粉基材料。由于环境问题、废物处理挑战和石油产品供应问题，生物塑料的生产出现了爆炸性增长。与生物塑料在工程应用中的更广泛接受相关的关键挑战之一是其高生产成本，脆性，缓慢的结晶速率和低熔体强度，这限制了它们在普通聚合物加工操作下的加工性能。它们相对较差的工程性能限制了它们在相对低价值的消费品中的应用。因此，提升生物聚合物的性能以使其性能与石油基聚合物的性能相匹配是一个非常活跃的研究领域。本研究项目将实施简单的共混和无溶剂反应改性工艺，以改善含PLA和PHA的生物聚酯化合物的结晶速率、加工性能和性能。我们在小规模上的初步研究表明，这种方法可以导致PLA的结晶行为和熔体强度的显着改善。该项目由E. I.加拿大蓬特公司的目标是在更大的规模上优化和开发这些工艺，表征所得产品，并进一步寻求在商业工艺和产品中的应用。具体目标包括生产足够量的适用于大规模配混的PHA;优化过氧化物引发剂和助剂的类型和量，并确定适当的加工条件;扩大工艺规模，以生产足够量的产品用于全面性能表征;并与适当的基准材料进行比较。预期的结果是开发出一种经济可行、无溶剂、环境友好的工艺，以获得具有良好工程性能的完全生物基产品。要求为一名硕士生提供资金，并为一名PDF和一名研究助理提供部分支助。

Bioplastics include thermoplastic polymers that are compostable and/or made from renewable resources, such as poly(lactic acid) (PLA), poly-3-(hydroxyalkanoates) (PHAs), and starch-based materials. The production of bioplastics has seen explosive growth driven by environmental concerns, waste disposal challenges and problems with the supply of petroleum products. Among the key challenges associated with more wide-spread acceptance of bioplastics in engineering applications are their high production costs, brittle nature, slow crystallization rates and low melt strength, which restrict their processability under common polymer processing operations. Their relatively poor engineering properties have limited their applications to relatively low-value, consumer goods. Upgrading the properties of biopolymers to match their performance to that of petroleum-based polymers is therefore an extremely active area of research. The present research project will implement simple blending and solvent-free reactive modification processes to improve the crystallization rates, processability and properties of biopolyester compounds, containing PLA and PHAs. Our preliminary investigations on a small scale have revealed that this approach can result in significant improvements in the crystallization behaviour and melt strength of PLA. The proposed project, supported by E.I. du Pont Canada, aims to optimize and develop these processes on a larger scale, to characterize the resulting products and to further seek applications in commercial processes and products. Specific objectives include the production of sufficient amounts of PHA suitable for use in large-scale compounding; the optimization of the type and amount of peroxide initiator and coagents and the identification of appropriate processing conditions; scale-up of the process to produce sufficient quantities for full property characterization; and comparison with appropriate benchmark materials. The expected outcome is the development of an economically viable, solvent-free, environmentally friendly process to obtain fully bio-based products, with good engineering properties. Funding is requested for a Master's student, and partial support for a PDF and a research assistant.