The selective recycling of mixed plastic waste of polylactic acid and polyethylene terephthalate by control of process conditions
(1970-1976) European Polymer Journal 47  #10 (2011)
Sánchez and Collinson ofCranfield University, United Kingdom, evaluated the glycolysis of postconsumer polyethylene terephthalate (PET) waste with catalysts of zinc acetate, zinc stearate and zinc sulfate, showing that zinc acetate was the most soluble and effective.  The chemical recycling by solvolysis of polylactic acid (PLA) and PET waste in either methanol or ethanol was investigated. Zinc acetate as a catalyst was found to be necessary to yield an effective depolymerization of waste PLA giving lactate esters, while with the same reaction conditions PET remains as an unconverted solid. This provides a strategy to selectively recycle mixed plastic waste by converting one plastic to a liquid and recovering the unreacted solid plastic by filtration.  (RDC 9/20/1011)

Effect of recycling on rheological and mechanical properties of poly(lactic acid)/polystyrene polymer blend
(3013-3019) Journal of Materials Science 46 #9 (2011)
Hamad, Kaseem and Deri, University of Damascus, Syria, studied the effect of multiple extrusion and injection of poly(lactic acid)/polystyrene polymer blend (PLA/PS) on its rheological and mechanical properties.  The results showed that the apparent viscosity of PLA/PS blend decreases monotonously with increasing the processing number. Also it was found that stress and strain at break of the blend decrease sharply after two processing cycles, whereas the processing number has a little effect on Young’s modulus.  (RDC 2/22/2011)

Preparation and Recycling of Plasticized PLA
(141–150)Macromolecular Materials and Engineering 296 #2 (2011)
Scaffaro of the Università di Palermo and Cittadella Universitaria, Italy, found that impact modifiers can effectively improve mechanical properties. Recycling led to a significant reduction in the impact strength; however a relatively high fraction of the other mechanical properties was still retained.  (RDC 2/24/2011)