𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞 : 𝐑𝐞𝐜𝐲𝐜𝐥𝐢𝐧𝐠 𝐞𝐥𝐞𝐜𝐭𝐫𝐨𝐧𝐢𝐜 𝐰𝐚𝐬𝐭𝐞 𝐩𝐥𝐚𝐬𝐭𝐢𝐜𝐬

𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞

𝐑𝐞𝐜𝐲𝐜𝐥𝐢𝐧𝐠 𝐞𝐥𝐞𝐜𝐭𝐫𝐨𝐧𝐢𝐜 𝐰𝐚𝐬𝐭𝐞 𝐩𝐥𝐚𝐬𝐭𝐢𝐜𝐬

A recyclable plastics waste stream of electrical and electronic equipment has previously been found to contain: 

acrylonitrile-butadiene-styrene copolymer (ABS, ∼40 wt%)

high impact polystyrene (HIPS, ∼40 wt%),

polypropylene (PP, ∼10 wt%), and

a rest fraction consisting mainly of other styrene-based thermoplastics

𝐎𝐩𝐭𝐢𝐦𝐚𝐥 𝐩𝐫𝐨𝐜𝐞𝐬𝐬𝐢𝐧𝐠 𝐜𝐨𝐧𝐝𝐢𝐭𝐢𝐨𝐧𝐬 𝐟𝐨𝐫 𝐞𝐥𝐞𝐜𝐭𝐫𝐨𝐧𝐢𝐜 𝐰𝐚𝐬𝐭𝐞 𝐩𝐥𝐚𝐬𝐭𝐢𝐜𝐬

𝐓𝐞𝐦𝐩𝐞𝐫𝐚𝐭𝐮𝐫𝐞 𝐚𝐧𝐝 𝐬𝐩𝐞𝐞𝐝 𝐩𝐚𝐫𝐚𝐦𝐞𝐭𝐞𝐫𝐬:

Favorable processing conditions with respect to tensile properties of the virgin blend were found at intermediate screw rotations (40 to 80 min−1) and relatively low barrel temperatures (170 to 220°C), which can be understood from the low onset of thermo-oxidative degradation at 200°C.

 

𝐒𝐭𝐢𝐟𝐟𝐧𝐞𝐬𝐬 𝐚𝐧𝐝 𝐲𝐢𝐞𝐥𝐝 𝐬𝐭𝐫𝐞𝐬𝐬 𝐜𝐡𝐚𝐫𝐚𝐜𝐭𝐞𝐫𝐢𝐬𝐭𝐢𝐜𝐬:

The recycled blend and recycled ABS, HIPS and PP showed higher stiffness and yield stress, but lower elongation at break than the corresponding virgin materials. The stiffness and yield stress of the blends were found mainly to follow the rule of mixtures of their components.

 

𝐌𝐚𝐭𝐞𝐫𝐢𝐚𝐥 𝐜𝐨𝐦𝐩𝐚𝐭𝐢𝐛𝐢𝐥𝐢𝐭𝐲 𝐢𝐬𝐬𝐮𝐞𝐬:

The elongation at break exhibited adverse characteristics indicating incompatibility between ABS, HIPS and PP. The significant variations in the elongation at break of the blends appeared to be due to the ABS component.

 

𝐓𝐡𝐞𝐫𝐦𝐚𝐥 𝐚𝐧𝐚𝐥𝐲𝐬𝐢𝐬 𝐫𝐞𝐬𝐮𝐥𝐭𝐬

𝐃𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐭𝐢𝐚𝐥 𝐬𝐜𝐚𝐧𝐧𝐢𝐧𝐠 𝐜𝐚𝐥𝐨𝐫𝐢𝐦𝐞𝐭𝐫𝐲 𝐟𝐢𝐧𝐝𝐢𝐧𝐠𝐬:

Differential scanning calorimetry showed an additional melt peak for the recycled blend compared to the virgin blend, otherwise the transitions were similar. The additional peak could be assigned to polyethylene in the PP component.

 

𝐓𝐡𝐞𝐫𝐦𝐨-𝐨𝐱𝐢𝐝𝐚𝐭𝐢𝐯𝐞 𝐝𝐞𝐠𝐫𝐚𝐝𝐚𝐭𝐢𝐨𝐧 𝐩𝐫𝐨𝐩𝐞𝐫𝐭𝐢𝐞𝐬: 

The onset of the thermo-oxidative degradation was found to be at almost 190°C in the case of the recycled blend, which was high considering that it was close to that of the virgin blend and higher than expected from the rule of mixtures of the recycled components.

 

References

Stenvall, E.; Tostar, S.; Boldizar, A.; Foreman, M. R. St. J. From International Polymer Processing (2013), 28(5), 541-549

source: SpecialChem