Active Disassembly

Self Disassembly Electronics Labour for disassembly represents a large fraction of recycling electronics Products that can non-destructively take themselves apart?? Active Disassembly with single generic trigger Not necessary to have records or plans on how to disassemble

Active Disassembly

Smart Materials Two basic families of smart materials – Shape Memory Alloys – Shape Memory Polymers Below a certain “transformation temperature” (Tx) they behave as standard engineering materials & can be used in the normal way Above this critical temp they undergo a shape change that can be reversible if the temperature is lowered again Tx can be controlled within a wide range of temperatures Proper use of different activation temperatures can enable a designer to create a product that could take itself apart sequentially

Shape Memory Alloys A group of metals made up of two or more metallic elements with particularly remarkable shape- changing and force provision properties As the temperature crosses or changes across a critical value (Tx), known as Austenite Finishing Temperature they undergo a large and predictable shape change the so called Shape Memory Effect (SME) Corrosion resistant and biocompatible Mechanical strength to form fasteners Tx can be placed between -190 C to 190 C

Shape Memory Alloys

Shape Memory Polymers (SMPs) Small group of plastics that can be formed using the normal processes SME in SMP is different from SMA and is not well understood Above their transformation temperature or glass transition temperature (Tg) SMPs loose their mechanical strength and return to their original formed shape after external forces are removed SMP has a very narrow Tg range ~1C. Unlike SMA plastics provide no significant force

Shape Memory Polymers (SMPs)

Shape Memory Effect One way – Material recovers to the original form one or more times but must be forcibly reshaped Two way – Material can recover many times to original shape and deform again to a secondary form after exposure to second stimulus Multi-way – Same response as two way but with multiple shapes reacting to multiple stimulus

SMA Actuators Released socketed IC’s from PCB’s Disassembly of product housings Nested Disassembly Keyboards CD Players Video games Telephones

SMA Actuators Characterisation – Non-destruction – Cost effectiveness – Range of permissible temperatures – Triggering temperatures Heat Sources – Air – Steam – Infrared – Water Baths

SMA Actuators

SMP Releasable Fasteners SMP screws placed inside the candidate product so that at Tg the device exhibits considerable mechanical property loss Effect of “letting go” Returned to their original shape after active disassembly

SMP Releasable Fasteners

Looking Forward Materials expensive Single Suppliers, Multinationals very slow to get involved Developed SME in conventional materials Need to get recyclers to adapt

Nanotechnology The science and technology of building devices, such as electronic circuits, from single atoms and molecules.

IBM Xenon Atoms on Nickel Using Atomic Force Microscopy

Carbon Nanotubes Extraordinary Strength Conductor and Semiconductor Properties, Electrical Conductivity 1000 times greater than copper Can be configured to be almost frictionless Can be configured to be excellent thermal conductors or insulators

Nanotechnology Ultimate aim is to manufacture and assemble objects one molecule at a time (bottom up manufacturing). – Reduced resource consumption through dematerialisation – Reduced chemical pollution through material substitution – Conversion of current waste into new resources – Enabling recycling at consumer household level

Nanotechnology Near zero tolerances Stronger, lighter and purer than current materials – Much greater efficiency in moving parts

Further Reading Chapter 23 Goldberg o.uk