Study On Recycling And Reuse Technology Of WRPUF

Waste Rigid Polyurethane Foam(WRPUF) is thermosetting material with three dimen- sional network structure. Because of its excellent performance and extensive use, a number of waste products need to be recycled. But WRPUF is neither soluble nor melt, it is difficult to recycle WRPUF. In a word, the technology research on recycling and reuse of WRPUF can reduce environmental pollution, make resource recycled and reused, realize green philosophy. Currently, the main methods at home and abroad of recycling are the physical recycling method, chemical recycling method, biological degradation recycling method, energy recycling method. From the angle of economy, directly recycling method can be the best, but the performance of products are very poor; Taking the use performance of recycled products into consideration, chemical recovery is better, but disadvantages are complex process, energy consumption, secondary pollution, etc; Energy recycling method isn't friendy for environment. In this paper, the WRPUF was recycled by force and chemical recycling methods. This method combines a lot advantages of the physical and chemical recycling methods. On one hand, it is easy to operate; On the other hand, it can improve performance of products. The main studying contents are as follows:1. Effect of type and content of anti-crosslinking agents on the anti-crosslinking of RPUF. The results are as follows:(1) Biochemical groups contain carbamate and uramido have different degrees of degra- deation with the increase of the content of anti-crosslinking. However, when the content of TEA was 35%, RPUF was burnt paste, it was quickly suffused with black color. In addition, the degradeation degree of different kinds of anti-crosslinking agents were as follows: TEPA> TEPA/DEG>TEA.(2) In three anti-crosslinking system, the GPC analysis showed that the order of the peak time was: RRPU(TEPA)>RRPU(TEPA/DEG)>RRPU(TEA), the order of molecular weight in THF solvent was RRPU(TEA)>RRPU(TEPA/DEG)>RRPU(TEPA), so the anti-cross linking agent of TEPA system had the strongest effect, TEA system was the weakest. 2. Effect of RRPU(TEPA/DEG) content, compatibilizer types and content, anti-crosslink ing agents system on the mechanical property, dynamic mechanical property, rheological pro- perty, crystallization property configuration structure in PP/RRPU composites.The results are as follows:(1) TEPA or TEA as anti-crosslinking agents, the surface of products had bubbles, which was poor performance. however, TEPA/DEG as anti-crosslinking agent, the surface of prod- ucts was no bubbles and flat; besides, it had better performance. TEPA/DEG as anti-crosslink ing agent, the best conditions of PP/RRPU/PP-g-MAH was 100:150:5, the mechanical proper- ties of products were as follows: impact strength was up to 16.66J/m, tensile strength was 15.33MPa, bending strength reached 66.90MPa, flexural modulus was 2727.66 MPa, HRR hardness was up to 112.71.(2) DMA analysis shows that the order of energy-storage modulus(E′) between 0℃and 70℃was PP/RRPU(TEA)/PP-g-MAH>PP/RRPU(TEPA)/PP-g-MAH>PP/RRPU(TEPA/DE G)/PP-g-MAH; The glass transition temperature (Tg) of PP/RRPU(TEPA/DEG)/PP-g-MAH, PP/RRPU(TEA)/PP-g-MAH, PP/RRPU(TEPA)/PP-g-MAH composites respectively were 130℃, 70℃, 108℃. The order of mechanical internal friction(tanδ) was PP/RRPU(TEPA/DEG) /PP-g-MAH>PP/RRPU(TEA)/PP-g-MAH>PP/RRPU(TEPA)/PP-g-MAH, which was consist- ent with the results of mechanics performance testing.(3) PLM analysis showed, the structure of PP spherulites was completely destroyed by RRPU, the crystallization of PP has changed.(4) SEM analysis showed, it has more closely structure and more strongly cohesive force between the PP matrix and RRPU obtained by TEPA/DEG anti-crosslinking agent; the section had clear evulsion and drag phenomenon, the final performance was that the mechani- cal properties have been improved.3. Effect of RRPU(TEPA/DEG) content, DOP content, anti-crosslinking agents system on the mechanical property, dynamic mechanical property, configuration structure in PVC/ RRPU composites. The results are as follows:(1) TEPA as anti-crosslinking agent, the surface of products was no bubbles and flat; besides, it had better performance. The best conditions of RRPU was 70%, DOP was 15%, the performance of blends was as follow: Impact strength of blends could up to 25.42 J/m, tensile strength was up to 43.17MPa, bending strength reached 76.19MPa, flexural modulus was 2849.59MPa, HRR hardness was 106.14.(2) DMA analysis showed that blending materials of energy-storage modulus (E′) and glass transition temperature (Tg) have been improved affer joining RRPU powder, which was higher than PVC. Besides, tanδhas also changed.(3) SEM analysis showed, it had more strongly cohesive force between the PVC matrix and RRPU obtained by TEPA anti-crosslinking agent; tensile fracture had clear evulsion and drag phenomenon, and there was no obvious phase interface. RRPU powder was tightly packed by PVC resin, mechanical properties were the best. 4. Effect of TEA and RRPU content on the mechanical property, rheological property, configuration structure in LDPE-g-MAH/RRPU composites. The results are as follows:(1) With the increase of TEA quality copies, impact strength and tensile strength gradually increases. when the quality copies of TEA is 30%, both of strength had the max values, and then they decreased gradually with the sequentially increasing of TEA. Bending strength of composites showed a gradual decrease phenomenon all the time. When the quality copies of LDPE-g-MAH:RRPU was 3:2, impact strength of LDPE-g-MAH/ RRPU composites could reached 168.4J/m, tensile strength was 16.17MPa, bending strength was up to 18.76MPa.(2) Non-newtonian index of LDPE-g-MAH/RRPU composites was less than 1, so the fusant of blends belong to pseudoplastic fluid, which presented "shear thinning phenomenon." When the content of TEA is 30%, in the constant shear stress, stable flow of the blend could be obtained within a wide temperature range, so it was easy molded.(3) The scanning electron microscope showed, the fracture section of composite that the ratio of LDPE-g-MAH:RRPU was 3:2 was more fuzzy, The RRPU powder dispersed in the substrate of PP more regularly, it also had smaller size; the cohesion of interphase was bigger, the mechanical properties were enhanced in macroscopical.