The new technology for recycling thermosetting polyurethane foamed material recycling
Polymer material is a product of high-tech development, polymer materials with its unique features and advantages of the people gradually applied to the production, all aspects of life, polyurethane () as , is widely used as a thermoset mattress furniture, noise insulation, automotive, footwear and construction materials and other fields. Although the PU has strong durability, but because of wear and replacement products still generate a lot of waste, and the current process of PU waste mostly landfill and incineration or cut up for low-value broken down into the carpet fiber, resulting in a great waste of resources, so the development of reprocessing method to recover critical to the sustainable use of PU waste of resources.
Recently, Professor William R. Dichtel at Northwestern University, to dibutyl tin (DBTDL) introducing a crosslinked PU foam, urethane exchange reaction so that the foam having a dynamic plasticity, and then using a twin-screw extruder to remove air foam, to form a higher value than the original PU foam material, such materials with a strong remodeling, it can be processed into a hard, durable plastic or soft flexible film, used in automobile bumpers, strap, shopping cart, or skateboard wheels and other products. This technology will enable further commercial PU waste recycling, and promote the further development of other thermoset materials reprocessing!
reprocessing PU foam
FIG, researchers first PU foam mixed with DBTDL catalyst solution 1, and melted at a high temperature; followed by bis after the screw extruder and then processing into a film PU foam or strips having excellent mechanical properties, this method can effectively remove not only the air in the foam, and high efficiency, fast foam remodeling.
Function of DBTDL catalyst
In order to determine DBTDL is added to the process in PU effect, researchers used PU film without catalyst test were compared. Stress relaxation FIG. 2 show the results of the analysis,DBTDL catalyst by treating the resulting film stress can be quickly restored, the process will undergo rapid dynamic conversion; catalyst without stress relaxation film is much slower, and can be further exhibits poor workability showed the catalyst DBTDL promote the use of reprocessed PU foam.
Comparative compression molding method and the twin-screw extruder
Figure 3 shows the the comparison researchers conventional compression molding method and the twin-screw extruder reprocessing PU foams, compression molding can be seen that the poor post-treatment effect of PU foams, through a twin screw extruder can be effectively to remove the air in the foam, to obtain a material having excellent mechanical properties; SEM characterization results are also evident, as compared with compression molding, twin-screw extruder to give a uniform material textures, there is no significant voids.
Extrusion [123 ] subsequently, in order to determine the actual significance of this twin-screw extruder method, researchers were extruded film tensile testing. Results As shown, compared with the conventional compression molding, air removal material during extrusion in a twin screw extruder 4 completely, the mechanical properties are well restored, compressed air molding material can not be completely removed to give , greatly reduce the tensile strength,
this is confirmed by the removal of air is critical to enhance the PU foam to the film from the reprocessing process performance. Characterization