Plastic is omnipresent and we are all aware of the challenges it poses. Let's review in music the conventional processing methods for plastic shaping, and recycling! Materials science and processes and intimately related, modifications at the materials level directly influences the process used, which in turn impacts the final material.
Start the playlist here: https://youtube.com/playlist?list=PLAtYx0idKu6sVCt0TwzHUxQlVdFqB8tgi
1. Synthesizing the polymer, most commonly via radical polymerization. The polymer chain structure is built at this stage that will be linked to its thermo-mechanical behavior: straight polymer chains will likely be semi-crystalline, crosslinked polymer networks will likely be more extensible (elastomers) or stiffer (thermosets). Highly branched polymer will get more viscous and high molecular weight will have a long reptation length linked to a high viscosity in molten state, etc. https://www.youtube.com/watch?v=ljvX-RMv_lw
2. Preparing the plastic formulation that contains the polymer(s) and additives like plasticizers, fillers, crosslinker, antioxidants. The formulation will greatly influence which process to use for shaping as well as the final properties of the material, including mechanical, UV-resistance, temperature resistance, porosity, etc. https://www.youtube.com/watch?v=eeu2Y3mdSkU
and
https://www.youtube.com/watch?v=_L4qauTiCY4&t=87s
3. Dispersive and distributive mixing is necessary to produce a homogeneous plastic formulation and create the "masterbatch", which are small pellets later used in the following processes.
https://www.youtube.com/watch?v=1wutkZ07ypA
and https://www.youtube.com/watch?v=DVP7Fjrnhlk
4. Compounding is the process to produce the masterbatch via pelletisation:
https://www.youtube.com/watch?v=IZCWPDoN4CU
and https://www.youtube.com/watch?v=a01QQZyl-_I
5. Near net shape processing, specially for thermoplastic formulations are the most commonly used processes for producing plastic parts like PVC pipes, PET bottles, PE plastic bags, PP bottle caps, etc. Extruding using single or double screws are typically used for elongated shapes https://www.youtube.com/watch?v=Cd_msPNeItU
,whereas injection molding is preferred for complex shapes with small features https://www.youtube.com/watch?v=FH7vl-mRgWE
6. After finishing, the final plastic material is obtained. The process chosen not only provides the shape but also influence the properties. For example, during extrusion, the polymer chains of high molecular weight polyethylene crystallize to form stiff fibers, a microstructure called in shish-kebab. https://www.youtube.com/watch?v=3bNITQR4Uso
7. After use, the plastic part is trashed. In the best closed-loop system, the trash is sorted to attain at least 99% purity to create a new masterbatch. https://www.youtube.com/watch?v=Vn2GjrsyE8U
8. After the sorting, the new masterbatch is used as any other masterbatch
9. Parts that cannot be recycled can still be valorized. This means burnt for energy reconversion: https://www.youtube.com/watch?v=CGyEd0aKWZE
To optimize the close-loop cycle of plastic shaping, we need you and the next generation! https://www.youtube.com/watch?v=MLpltDCoieU
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