Recycling polymeric waste from electronic and automotive sectors into value added products

Highlights

• Polymer fraction was separated from waste PCBs by froth floatation.

• Addition of waste PCBs to polypropylene reduced the overall impact strength.

• Up to 9 wt.% rubber was added to PP/25 wt.% PCB composites as impact modifier.

• Mechanical, structural, rheological properties of composites were investigated.

• Electronic and automotive waste were successfully utilized in PP composites.

Abstract

The environmentally sustainable disposal and recycling of ever increasing volumes of electronic waste has become global waste management issue. The addition of up to 25% polymeric waste PCBs (printed circuit boards) as fillers in polypropylene (PP) composites was partially successful: while the tensile modulus, flexural strength and flexural modulus of composites were enhanced, the tensile and impact strengths were found to decrease. As a lowering of impact strength can significantly limit the application of PP based composites, it is necessary to incorporate impact modifying polymers such as rubbery particles in the mix. We report on a novel investigation on the simultaneous utilization of electronic and automotive rubber waste as fillers in PP composites. These composites were prepared by using 25 wt.% polymeric PCB powder, up to 9% of ethylene propylene rubber (EPR), and PP: balance. The influence of EPR on the structural, thermal, mechanical and rheological properties of PP/PCB/EPR composites was investigated. While the addition of EPR caused the nucleation of the β crystalline phase of PP, the onset temperature for thermal degradation was found to decrease by 8%. The tensile modulus and strength decreased by 16% and 19%, respectively; and the elongation at break increased by ~71%. The impact strength showed a maximum increase of ~18% at 7 wt.%–9 wt.% EPR content. Various rheological properties were found to be well within the range of processing limits. This novel eco-friendly approach could help utilize significant amounts of polymeric electronic and automotive waste for fabricating valuable polymer composites.

Graphical abstract

Keywords

E-waste / Polymer composites / Recycling / Rubber / Waste PCBs / Filler

References

[1] Baldé C P ,  Wang F, Kuehr  R, Huisman J . The Global E-Waste Monitor- 2014. Bonn, Germany: United Nations University, IAS- SCYCLE, 2014, 1

[2] Cayumil R, Khanna  R, Ikram-Ul-Haq M ,  Rajarao R ,  Hill A, Sahajwalla  V. Generation of copper rich metallic phases from waste printed circuit boards. Waste Management (New York, N.Y.), 2015, 34(10): 1783–1792 

[3] Shen C, Chen  Y, Huang S ,  Wang Z, Yu  C, Qiao M ,  Xu Y, Setty  K, Zhang J ,  Zhu Y, Lin  Q. Dioxin-like compounds in agricultural soils near e-waste recycling sites from Taizhou area, China: Chemical and bioanalytical characterization. Environment International, 2009, 35(1): 50–55 

[4] Widmer R, Oswald-Krapf  H, Sinha-Khetriwal D ,  Schnellmann M ,  Böni H . Global perspectives on e-waste. Environmental Impact Assessment Review, 2005, 25(5): 436–458 

[5] Kasper A, Berselli  G, Freitas B ,  Tenório J ,  Bernardes A ,  Veit H. Printed wiring boards for mobile phones: Characterization and recycling of copper. Waste Management (New York, N.Y.), 2011, 31(12): 2536–2545 

[6] Cayumil R, Khanna  R, Rajarao R ,  Mukherjee P S ,  Sahajwalla V . Concentration of precious metals during their recovery from electronic waste. Waste Management (New York, N.Y.), 2016, 57: 121–130 

[7] Arshadi M, Mousavi  S M. Enhancement of simultaneous gold and copper extraction from computer printed circuit boards using Bacillus megaterium. Bioresource Technology, 2015, 175: 315–324

[8] Bigum M, Brogaard  L, Christensen T H . Metal recovery from high-grade WEEE: A life cycle assessment. Journal of Hazardous Materials, 2012, 207: 8–14 

[9] Guo J, Tang  Y, Xu Z . Wood plastic composite produced by nonmetals from pulverized waste printed circuit boards. Environmental Science & Technology, 2009, 44(1): 463–468 

[10] Hall W J, Williams  P T. Separation and recovery of materials from scrap printed circuit boards. Resources, Conservation and Recycling, 2007, 51(3): 691–709 

[11] Hopewell J, Dvorak  R, Kosior E . Plastics recycling: challenges and opportunities. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 2009, 364(1526): 2115–2126 

[12] Dodds J, Domenico  W, Evans D ,  Fish L, Lassahn  P, Toth W . Scrap Tires: A Resource and Technology Evaluation of Tire Pyrolysis and Other Selected Alternate Technologies. Washington, DC: US Department of Energy, 1983

[13] Zaharia M, Sahajwalla  V, Kim B C ,  Khanna R ,  Saha-Chaudhury N ,  O’Kane P ,  Dicker J ,  Skidmore C ,  Knights D . Recycling of rubber tires in electric arc furnace steelmaking: Simultaneous combustion of metallurgical coke and rubber tyres blends. Energy & Fuels, 2009, 23(5): 2467–2474 

[14] Igwe I O, Ejim  A A. Studies on mechanical and end-use properties of natural rubber filled with snail shell powder. Materials Sciences and Applications, 2011, 2(07): 801–809 

[15] Eldin N N, Senouci  A B. Rubber-tire particles as concrete aggregate. Journal of Materials in Civil Engineering, 1993, 5(4): 478–496 

[16] Al-Salem S M, Lettieri  P, Baeyens J . Recycling and recovery routes of plastic solid waste (PSW): A review. Waste Management (New York, N.Y.), 2009, 29(10): 2625–2643 

[17] Sahajwalla V, Cayumil  R, Khanna R ,  Ikram-Ul-Haq M ,  Rajarao R ,  Mukherjee P S ,  Hill A. Recycling polymer-rich waste printed circuit boards at high temperatures: Recovery of value-added carbon resources. Journal of Sustainable Metallurgy, 2015, 1(1): 75–84 

[18] Guo Q, Yue  X, Wang M ,  Liu Y. Pyrolysis of scrap printed circuit board plastic particles in a fluidized bed. Powder Technology, 2010, 198(3): 422–428 

[19] Zhou Y, Qiu  K. A new technology for recycling materials from waste printed circuit boards. Journal of Hazardous Materials, 2010, 175(1–3): 823–828 

[20] Zhou Y, Wu  W, Qiu K . Recycling of organic materials and solder from waste printed circuit boards by vacuum pyrolysis-centrifugation coupling technology. Waste Management (New York, N.Y.), 2011, 31(12): 2569–2576 

[21] Khanna R, Ikram-Ul-Haq  M, Cayumil R ,  Rajarao R ,  Sahajwalla V . Novel carbon micro fibers and foams from waste printed circuit boards. Fuel Processing Technology, 2015, 134(473): 473–479

[22] Mou P, Xiang  D, Duan G . Products made from nonmetallic materials reclaimed from waste printed circuit boards. Tsinghua Science and Technology, 2007, 12(3): 276–283 

[23] Guo J, Li  Q J, Rao Z ,  Xu. Phenolic molding compound filled with nonmetals of waste PCBs. Environmental Science & Technology, 2007, 42(2): 624–628 

[24] Guo J, Rao  Q, Xu Z . Application of glass-nonmetals of waste printed circuit boards to produce phenolic moulding compound. Journal of Hazardous Materials, 2007, 153(1–2): 728

[25] Zheng Y, Shen  Z, Cai C ,  Ma S, Xing  Y. The reuse of nonmetals recycled from waste printed circuit boards as reinforcing fillers in the polypropylene composites. Journal of Hazardous Materials, 2009, 163(2–3): 600–606 

[26] Wang X, Guo  Y, Liu J ,  Qiao Q, Liang  J. PVC-based composite material containing recycled non-metallic printed circuit board (PCB) powders. Journal of Environmental Management, 2010, 91(12): 2505–2510 

[27] Peijs T. Composites for recyclability. Materials Today, 2003, 6(4): 30–35 

[28] Kumar A, Choudhary  V, Khanna R ,  Cayumil R ,  Ikram-ul-Haq M ,  Mukherjee P S ,  Sahajwalla V . Polymer composites utilizing electronic waste as reinforcing fillers: mechanical and rheological properties. Current Applied Polymer Science, 2016, 1(1): 1

[29] Premalal H G B ,  Ismail H ,  Bahrain A . Comparison of the mechanical properties of rice husk powder filled polypropylene composites with talc filled polypropylene composites. Polymer Testing, 2002, 21(7): 833–839 

[30] Matsuda Y, Hara  M, Mano T ,  Okamoto K ,  Ishikawa M . Effect of the compatibility on toughness of injection‐molded polypropylene blended with EPR and SEBS. Polymer Engineering and Science, 2006, 46(1): 29–38 

[31] Wahit M U, Hassan  A, Ishak Z A M ,  Rahmat A R ,  Othman N . The effect of rubber type and rubber functionality on the morphological and mechanical properties of rubber-toughened polyamide 6/polypropylene nanocomposites. Polymer Journal, 2006, 38(8): 767–780 

[32] Tordjeman P, Robert  C, Marin G ,  Gerard P . The effect of α, β crystalline structures on the mechanical properties of polypropylene. European Physical Journal E, 2001, 4(4): 459–465 

[33] Grein C, Gahleitner  M. On the influence of nucleation on the toughness of iPP/EPR blends with different rubber molecular architectures. Express Polymer Letters, 2008, 2(6): 392–397 

[34] Ehsani M, Borsi  H, Gockenbach E ,  Morshedian J ,  Bakhshandeh G R . An investigation of dynamic mechanical, thermal, and electrical properties of housing materials for outdoor polymeric insulators. European Polymer Journal, 2008, 40(11): 2495–2503 

[35] Liang J Z, Li  R K Y. Rubber toughening in polypropylene: A review. Journal of Applied Polymer Science, 2000, 77(2): 409–417 

Acknowledgements

Authors gratefully acknowledge Department of Science and Technology (DST) India for providing financial support for the project under the Australia-India Strategic Research Fund Round 6 (No. ST060041).

Declaration of Conflicting Interests

Authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

RIGHTS & PERMISSIONS

2017 Higher Education Press and Springer-Verlag GmbH Germany