We took the time in 2020 to recycle our electro-functional paper wastes we accumulated in our Canadian antenna in Montreal. These are wastes paper collected during our productions, classrooms an the ones of our Montreal collaborators within the last years.
It represented only around 5kg of paper but this isis enough to reproduce 600 A4 sized sheets (@ 100GSM)
The main objective was to re-pulp these wastes reproduce new efficient electrically resistive paper sheets at St Armand Paper Mill in Montreal. Here are various points that hold our attention while testing this recycling process.
Re-Pulping
The recycling is quite easy when reproducing something from a single aw-materials. This is our case here and re-pulping our wastes simply involved to remix pieces into water and mix at with a pulper. The pulper is sort of like a kitchen mixer whose goal is to individualize again the fibers and fines elements.
It takes some time depending on the paper for the water to fully moist the paper wastes and it is better to prepare this in advance, possibly even with hot water if necessary prior to re-pulping.
Then, the pulping parameters are the shear force (a few hundred RPM) and the shear time (a few minutes). At the end you must cleary see the individualised fibres and no flocs in your mix. A consistency of below 5% solid per liter is important here to properly separated fibre and see the result.
Production process
This adorable paper mill partially produces handsheets with classic wired frames from pulp mixed with water in a bucket. Wired frames are plunged a 45% at the bottom of the bucket and then pulled out vertically out of the bucket. The water will then flow through the wire while the fibers will accumulated over its surface. Skilled papermakers produce the most uniform sheets.
Carbon Particle Sizes
Carbon particles sizes present in our papers wastes are vey tiny ranging from 10nm. These particles are mixed with water and are more or less attached to these depending on the chemicals added and the shear rate in the fluid. THus, many pigment will be lost and flow with water during the paper production process.
Chemical Additions
Various chemicals are most often added at very low quantities with the pulp for various purpose. In our case we use so called retention aids or other binding agents whose goal is to bonf the pigments with the fibers so as to increase the pigments retention in the final paper.
Shear forces
Shear forces will challenge to bonidng between the fibers and the fillers, High shear forces are great when recycling if we want to separate fibers from other materials inside it (centrifugator), but this is not good for the retention of the carbon pigments duringg production in our case.