Jan van Eck: I was under the impression that a plastic sealing film can be manufactured using corn starch as the base material. It then disintegrates in a few months, and quite rapidly if exposed to UV light (sunlight). Can you shed any light on this as a film packaging material? Or does price/cost keep it off the market?
Jan, I like your question and tongue in cheek about shedding light on the film packaging material! I sense the corn starch plastic degrading as I write.
Corn starch is made into polylactic acid or PLA or PLLA or other similar types. It had rudimentary abilities for being made into a sealant layer when i left the packaging industries. It was monoextruded.
With different types of polyethylene and ethylene copolymers, one could add in maleic anhydride to the batch and help it be more suitable for sealing or attaching one type of plastic to another. Also, PLA is thermally sensitive, I recall it does not stand up to the extrusion so well. This happened with the material we call SARAN (PVDC), which was horrible to extrude yielding HCL gas in compounding and in extrusion. However, we learned many tricks and ways to mitigate PVDC's temperature stability. Yes you can add additives to PLA for heat stability and perfect it further. I am sure that has been done by now. It probably barely holds up, but then that would be the point right?
I worked in irradiating films to aid in making it shrink more easily, somewhat modifying the structure of the film where it crosslinks. This could also aid in making the PLA more heat stable for other applications.
I did read up on PLA's some more. Remarkably, they are used in 3D Printing and melt quite easily.
My other comments: We can iteratively improve and reduce plastic usage with our known technologies. Structural plastic does help us in so many ways and can be recycled. Much flexible packaging can be recycled into composites with wood fiber. Flexible packaging could be exempted for necessary foods such as meat and vegetables.
Now those 'disposable' grocery bags should go by the wayside! People can bring their own to the store and by reusable bags.
I don't see how the energy and carbon footprint ( less plastic) could be reduced further unless we went to regionalized or localized micro-manufacturing and agricultural centers.
i
