6.07 Innovative polymers and polymer-based composites for engineering and design applications

In this project, polymers and polymer-based composites specifically designed for Additive Manufacturing (AM) and with improved mechanical and functional properties will be designed and produced to evaluate their processability in AM technologies. In particular, the project will be focused on both photo-/thermo-curable and thermoplastic matrixes with specific emphasis on sustainability and environmental impact. Taking into account the different physical and chemical behavior of thermoset and thermoplastic polymers and their impact on related AM technologies, two distinct tasks are planned, respectively.
Innovative formulations will be designed and prepared with the specific aim to use materials with advanced mechanical and functional properties and/or deriving from renewable resources in order to facilitate the ongoing transition toward a circular economy. The formulations will be tested and developed in terms of processability with the selected AM technologies. Process parameters will be investigated and optimized in order to control the dimensional resolution and the ultimate properties of the materials and parts obtained.

Task 1 – Innovative photocurable and hybrid polymer formulations, including from renewable sources, with improved properties
In the present task, the AM technologies object of investigation will be the vat photopolymerization technologies (stereolithography SLA, digital light processing DLP, etc.) and the liquid deposition modeling (LDM).
Below are some examples of materials, properties and specific applications.

• Development of 3D printable structures with advanced characteristics such as self-healing, recyclability and biodegradability as well as functional properties such as electrical conductivity, photoresponsitivity, shape memory, etc. • Development on bio-based and/or biodegradable UV-curable resins filled with ceramic particles for DLP. Chemical composition will be opportunely tuned to achieve optimal rheological properties and high-quality 3D-printed parts. To further improve mechanical, physical and aesthetical properties, polymer-ceramic composites will be investigated as well. To this extent, the interactions between the ceramic filler and the polymer matrix will be investigated, depending on the ceramic solid loading and their different refractive indexes.
• Development of innovative hybrid formulations suitable for 3D printing by LDM with the aim of minimizing the use of resources and the environmental impact of products; reversibly crosslinked composite materials containing bio-based fillers will be also developed.

Task 2 – Innovative thermoplastic (bio) polymers also reinforced with particles or short fibres with improved properties
In the present task, the selected AM technologies will be the most important for thermoplastics: fused filament fabrication (FFF), selective laser sintering (SLS), direct pellet printing (DPP).
Below are some examples of materials, properties and specific applications.

• Structural design and production of mechanical parts made of AM particles or short fibre-reinforced (bio) polymeric materials. The aim is to develop integrated methodologies for the structural design and production of industrial components made of micro and/or nanoparticles and/or short fibers (also coming from waste biomasses) reinforced polymeric materials using AM technologies. The activities will involve studying and developing new compounds for the additive fabrication of structural and functional components for automation with enhanced properties. In particular, the second life of plastics and filler (metal powders or carbon-based filler) will also be envisaged to produce polymer compounds and conductive polymer composites (CPCs).
• Development of polymeric blends characterized by origin from renewable sources and biodegradability at the end of their life. In particular, formulations based on binary and/or ternary blends of polyesters with bioplasticizers and compatibilizing agents will be designed to provide mutual compatibility between the polymers, increase their mechanical properties and thermal stability. The specific objective is to arrive at formulations with thermo-mechanical properties comparable to those of traditional polyolefins but with the additional scenario of biodegradation at the end of their life. To this end, the envisaged formulations will also include PHBV prepared in the laboratories of the research group. The selection of natural reinforcing fillers is also envisaged to enhance the environmental sustainability and biodegradability of the developed formulations.
• Rheological assessment and 3D extrusion printing of polymeric formulations reinforced with micro- and nano-particles for several engineering applications. Nano-CT analysis to investigate the internal architecture/morphological parameters, particle distribution and presence of defects (porosity, cracks).
• Development of 3D AM structures with suitable mechanical/functional features according to the application through the design of different devices, in the form of 3D solid, cellular, lattice, functionally-graded or solid-lattice hybrid structures.