Eric Billett

Shape memory alloy actuators for active disassembly using ‘smart’ materials of consumer electronic products

Abstract This paper reports the preliminary to current development of Shape Memory Alloy (SMA) actuators within their application in ‘Active Disassembly using Smart Materials’ (ADSM). This non-destructive self-dismantling process is to aid recycling of consumer electronic products. Actuators were placed in single and multi-stage hierarchical temperature regimes after being embedded into macro and sub-assemblies of electronic product assemblies. Findings include active disassembly and a hierarchical dismantling regime for product dismantling using developed SMA actuators embedded into candidate products.

Ecological Footprint Analysis Applied to Mobile Phones

Ecological footprints (EF) have been used for more than 15 yr as an aggregate measure of sustainability of geographical regions, but also for certain products and activities. EF analysis measures the bioproductive areas required to produce resources such as crops and timber, the directly occupied areas for infrastructure, and areas for absorbing waste flows (mostly limited to carbon dioxide) in a given year for a defined population. The need to extend ecological footprint analysis to electronic products arose because so far, mobile phones have mainly been evaluated using life-cycle assessments with a focus on toxicity, end-of-life management, and energy use, thus ignoring the wider sustainability implications. This article presents the footprint results from three mobile phone case studies. To establish the land areas consumed by the mined materials used in electronic products, a database was developed based on literature data and on approximations from the density and overburden of materials. The relationship between abundance and overburden values was used in a regression analysis to estimate energy requirements in materials extraction where other data were not available. Using a life-cycle assessment approach, environmental burdens for producing and using a mobile phone were calculated and transformed into the instantaneous rate of resource consumption. Key results were that different electronic products have different ecological footprints and that the methodology proved sensitive enough to reveal differences in small electronic products and for monitoring technologies that use bioproductive space efficiently.

An initial investigation into active disassembly using shape memory polymers

Abstract The aim of the work was to demonstrate an alternative to conventional end-of-life (EOL) disassembly strategies such as robotic or hand dismantling. This initial investigation reports the disassembly of consumer electronic products using smart materials in the design of embedded releasable fasteners. A series of products was tested in a variety of different ways using shape memory polymers (SMPs). Tests were run on macroassemblies and subassemblies of telecommunications goods. The devices designed with SMP used two distinct properties of the material suited to active disassembly: the mechanical property loss (MPL), in this case a loss of rigidity in the thread of the SMP screws; the shape memory effect (SME), a change in form, resulting in this case in the loss of moulded thread from SMP shape memory effect screws. Once SMP components were developed and embedded into the candidate products, timed disassembly experiments were conducted. These tests used infrared, air jet and water bath methods for applying heat to trigger the SMP devices. Once the trigger temperature was reached, shape change and property loss occurred in the screws and brackets, allowing assembly release.

Active disassembly using shape memory polymers for the mobile phone industry

This paper reports results the application of shape memory polymer (SMP) technology to the active disassembly of modern mobile phones. The smart material SMP of polyurethane (PU) composition was employed. Two different types of SMP fasteners were created for these experiments. With these smart material devices, it is possible for products to disassemble themselves at specific triggering temperatures at EoL. The two designs were compared for disassembly effectiveness. The disassembly technique is termed active disassembly using smart materials (ADSM), and has been successfully demonstrated on a variety of mobile phones. Whilst developed primarily as a universal disassembly technique, cost effectiveness and time performance is apparent. Heat sources of +90, +100 and a range of +67 to +120/spl deg/C were employed to raise the releasable fasteners above their trigger temperatures: in the case of SMP this would be the glass transition temperature (Tg). The development of releasable fasteners and applications in electronic products is described.

Preliminary investigations of active disassembly using shape memory polymers

This paper reports initial results in the application of shape memory polymer (SMP) technology to the active disassembly of electronic products. The smart material SMP of polyurethane (PU) composition was employed. Created for these experiments were novel SMP releasable fasteners, with which it is possible to effectively disassemble products at specific triggering temperatures at the end of their life (EoL). This disassembly technique is termed active disassembly using smart materials (ADSM), and has been successfully demonstrated on a variety of products using other smart materials. Whilst developed primarily as a universal disassembly technique, cost effectiveness is apparent. Heat sources of +70, +100 and +225/spl deg/C were employed to raise the releasable fasteners above their trigger temperatures: in the case of SMP this would be the glass transition temperature (Tg). The development of releasable fasteners and applications in electronic products is described.

Electrically self-powered active disassembly

Abstract Active disassembly using smart materials is a concept developed at Brunel University for the design of assemblies with the built-in capability for easy separation of components for recycling on exposure to certain triggering conditions. Such assemblies incorporate shape memory alloy (SMA) actuators in the product housings. These actuators in the form of clips can undergo a shape change (shape memory effect) on going above a transition temperature, and exert a force to effect disassembly. Hitherto, such a change in temperature has been effected by direct heat input external to the assembly. It is now shown in the case of assemblies that contain battery power sources, firstly, that disassembly can be achieved using the residual electrical energy in waste batteries to heat the SMA actuator electrically and, secondly, that there is enough energy left in end-of-life batteries of mobile phones and end-of-life vehicles to trigger at least 4 and 16 devices respectively.

Open windrow composting of polymers: an investigation into the rate of degradation of polyethylene

Abstract The compostability of degradable polymers under open windrow composting conditions is explored within this paper. Areas for consideration were the use of, and impacts of, degradable polyethylene (PE) sacks on the composting process and the quality of the finished compost product. These factors were investigated through polymer weight loss over the composting process, the amount of polymer residue and chemical contaminants in the finished compost product, the windrow temperature profiles and a bioassay to establish plant growth and germination levels using the final compost product. This trial also included a comparative study of the weight loss under composting conditions of two different types of ‘degradable’ polymer sacks currently on the European market: PE and a starch based product. Statistical analysis of the windrow temperature profiles has led to the development of a model, which can help to predict the expected trends in the temperature profiles of open compost windrows where the organic waste is kerbside collected using a degradable PE sack.

Comparison between audio and tactile systems for delivering simple navigational information to visually impaired pedestrians

Many of the current GPS (Global Positioning Systems) navigation aids use an audio method to deliver navigation information to the user. For the visually impaired person this method can be problematic. The visually impaired pedestrian relies heavily on information contained within the ambient sound environment; for location and orientation information, navigation information and, importantly, safety information. In this article we present the design of an innovative tactile interface and verification of results obtained through experimental trials. This pilot study compared the efficiency of the tactile interface to an audio method of delivering simple navigational information. The findings indicate that the tactile interface could be used successfully by blind and sighted pedestrians and may offer advantages over auditory interfaces.

Development of a method for calculating the environmentally optimum lifespan of electrical household products

Abstract This paper considers the idea that for many products there is a particular length of lifespan for which the environmental impact of the item is at a minimum. It is suggested that for some types of product this ideal lifespan is not, as is often believed, ‘as long as possible’ but until the performance of a new product justifies replacing the existing one. Electrical household appliances are identified as a product group for which this issue is particularly relevant. It is proposed that the improvement over time of use-phase energy consumption shown by many products in this group means that at a certain point it is environmentally beneficial for the customer to replace their existing machine with the latest model. The paper suggests that it is possible to calculate this point in the life of the product when replacement is most beneficial from information about new and existing machines. The development of a method for calculating this optimum lifespan from energy consumption data is described, using a dishwasher to demonstrate the technique. Using the equation devised, the environmentally optimum lifespan of a dishwasher is found to be 8.1 years in 2003.

An Evaluation of Degradable Polyethylene (PE) Sacks In Open Windrow Composting

The compostability of degradable polyethylene under open windrow composting conditions is explored within this paper. Areas for consideration were the use of, and impacts of, degradable polyethylene sacks on the composting process and the quality of the finished compost product. These factors were investigated through tracking the polyethylenes weight loss over the composting process; the amount of polymer residue and chemical contaminants in the finished compost product; the windrow temperature profiles and a bioassay to establish plant growth and germination levels using the final compost product. Statistical analysis of the windrow temperature profiles has led to the development of a model, which can help to predict the expected trends in the temperature profiles of open compost windrows where the organic waste is kerbside collected using a degradable polyethylene sack.