New technique to make transparent polythene films as strong as aluminium that could be used in impact resistant glazing, windscreens, and displays
Research led by Professor Ton Peijs of WMG at the University of Warwick and Professor Cees Bastiaansen at Queen Mary University of London, has devised a processing technique that can create transparent polythene film that can be stronger as aluminium but at a fraction of the weight, and which could be used use in glazing, windscreens, visors and displays in ways that add strength and resilience while reducing weight.
In a new research paper entitled “Glass-like transparent high strength polyethylene films by tuning drawing temperature.” Published online today - 1st April 2019 - in the Journal Polymer, the authors show that after carefully selecting the type polythene and by tuning the temperature during the creation of oriented polythene films a balance can be created that produces a highly useful and lightweight transparent material with a significant strength and resilience approaching, and in some ways, exceeding that of metals.
Previously anyone looking to replace heavy and often brittle glasses with a transparent plastic have looked at conventional transparent plastics like polycarbonate (PC) and poly(methylmethacrylate) (PMMA) both of which possess relatively unsatisfactory mechanical performance compared to an engineering material like aluminium.
Current methods of creating high strength plastic films such as hot-drawing of high-density polyethylene (HDPE) can lead to materials that can compete or even out-perform traditional engineering materials like metals.
“The microstructure of polymers before drawing very much resembles that of a bowl of cooked spaghetti or noodles, while after stretching or drawing the molecules become aligned in a way similar to that of uncooked spaghetti, meaning that they can carry more load” explains Yunyin Lin, a PhD student in Professors Peijs and Bastiaansen’s team.
However, drawn polythene materials normally have an opaque appearance due to defects and voids introduced by the drawing process, limiting applications where both mechanical properties and optical transparency are required.
Some success has recently been achieved by using highly specific additives in hot-drawn HDPE materials that can then produce 90% transparency while giving high strength. However, the research team led by Professors Peijs and Bastiaansen have now developed a new post-manufacturing technique for HDPE that endows strength and resilience while preserving transparency without using additives.
The researchers took HDPE polythene sheets and drew out these sheets at a range of temperatures below the melting temperature of HDPE. By tuning the drawing temperature they could achieve a transparency of 90% in the visible range. However, the best balance between strength and transparency was achieved at drawing temperatures between 90 and 110 degrees centigrade.
“We expect greater polymer chain mobility at these high drawing temperatures to be responsible for creating fewer defects in the drawn films, resulting in less light scattering by defects and therefore a higher clarity”
The highly transparent films possess a maximum resilience or Young’s Modulus of 27 GPa and a maximum tensile strength of 800 MPa along the drawing direction, both of which are more than 10 times higher than those of PC and PMMA plastics. For comparison, aluminium has a Young’s Modulus of 69 GPa and aerospace grade aluminium alloy can have tensile strengths up to around 500 MPa. However, polythene has a density of less than 1000 kg/m3 while aluminium has a density of around 2700 kg/m3, meaning that on weight basis these high strength transparent polymer films can outperform such metals.
Professor Ton Peijs in WMG at the University of Warwick concludes that:
“Our results showed that a wide processing window ranging from 90 °C to 110 °C can be used to tailor the required balance between optical and mechanical performance. It is anticipated that these lightweight, low-cost, highly transparent, high strength and high stiffness HDPE films can be used in laminates and laminated composites, replacing or strengthening traditional inorganic or polymeric glass for applications in automotive glazing, buildings, windshields, visors, displays etc.”
Grad jobs are now being advertised at WMG, University of Warwick. There are 13 jobs available starting September 2019, which will be working on projects such as Automation Systems, Energy Innovation and Smart Connected and Autonomous Vehicles.
The closing date to apply is the 15th March 2019.
Following the successful launch of the WMG Graduate Development Programme last year, WMG has launched recruitment for its 2019 graduate programme, with 13 places available to graduates from all Higher Education Institutes.
The programme is designed for aspiring engineers and follows three pathways – Automation Systems, Energy Innovation and Smart Connected and Autonomous Vehicles. The Graduate Trainee’s will be working alongside academics, and industry partners.
Starting in September 2019, the programme will last for two years during which graduates will complete five/six different placements, each offering the opportunity to develop their engineering skills and knowledge in key areas, with the chance to apply these skills to real-world research and development.
On completion of the scheme, the graduates will be equipped with the skills to apply for roles such as a Project Engineer or Project Manager, or pave the way for future studies such as a Master’s or PhD.
"There is so much support offered here, not just from your peers, but from your mentors and managers too. There are regular discussions on how you can develop and enhance your skills and knowledge to steer your career in your chosen direction. There is such a variety of opportunities offered, such as the chance to attend professional conferences, as well as gaining a project management qualification. Progression and development is at the heart of the organisations culture and it really shows.”
WMG Graduate Trainee Engineer Ben Ayre, also joined the scheme last year following his graduation from the University of Warwick.
“My highlights so far have included working on multi mullion pound projects with a variety of organisations to achieve real impact. I’ve also had the opportunity to undertake professional development courses and qualifications. It has also been great to have the support of the other graduates, making the transition between university and work life easier. I would advise anyone who is wants to work in a varied team working on lots of cutting edge projects to apply as it is an excellent scheme.”
Trainees benefit from a training salary of £26,243 a year.
You can find out more about the graduate development programme at our dedicated careers page www.warwick.ac.uk/WMGGraduateScheme
More people are physically active due to the Sweatcoin app which rewards you for walking – researchers at the Institute of Digital Healthcare, WMG at the University of Warwick have found. Sweatcoin gets people outdoors and walking to earn a virtual currency to spend in their marketplace.
Reaching your target number of steps a day is a little easier for those using the app called Sweatcoin which rewards users with a virtual currency for walking.
Sweatcoin works by converting the number of steps recorded on your phone into a virtual currency of Sweatcoins.
Every 1,000 steps generate 0.95 Sweatcoins and these can be used to purchase products on the in-app marketplace, (with prices ranging from 5 to 20,000 Sweatcoins), in local shops, or be transferred between other users.
Currently, steps recorded outdoors are rewarded due to the use of a GPS-based verification algorithm used to stop people cheating their phone’s step-counting algorithm.
The Institute of Digital Healthcare, WMG at the University of Warwick analysed daily step count data from 6000 users of the app, and found that there was a sustained average increase of nearly 20% in daily step count over a 6-month period after users had registered with the app, in comparison with a 3-month period prior to downloading the app.
Following a survey on a sample of the original 6000 users, those who were classified as less physically active and overweight were found to be most likely to increase their daily step count when using the app, meaning that Sweatcoin was having impact on an important section of the population who previously had low levels of physical activity.
Dr Mark Elliott, Assistant Professor at the Institute of Digital Healthcare, WMG - University of Warwick comments:
“We were delighted to have the opportunity to work with Sweatcoin and investigate how their app impacts on physical activity behaviour change. By analysing the daily step count data from a sample of Sweatcoin users and combining this with data from the surveys and focus groups facilitated by our researchers, we were able to identify which types of user had shown the biggest change in terms of increased physical activity from using the app.”
Anton Derlyatka co-founder at Sweatcoin comments:
"Incentivising people to walk more is key to improving levels of sustained physical activity. Yet, traditional ideas such as providing educational seminars or discounted gym passes, just don’t deliver. The University of Warwick found that an economy built on movement, as created by Sweatcoin, establishes sustained motivation for people to be more active. For an increasingly sedentary population facing an obesity and wellness crisis, these are significant findings.”
Lord Philip Hunt, Sweatcoin Advisory board member commented:
“Most health apps and initiatives tend to be aimed at those who are already active. Sweatcoin has huge potential in encouraging and incentivising non-active people to get walking. Given the health gains that can be achieved through increased physical activity, this is the kind of breakthrough we need to help motivate who can benefit most.”
WMG, at the University of Warwick, has launched a new Master’s programme with Royal Mail Group which is designed to develop leadership talent in technology based industries. A wide range of Royal Mail Group staff, from all levels of management, are the first participants in this new programme.
Twenty five Royal Mail Group staff enrolled with WMG in September 2018 in a three year development programme which will enable the participants to gain a Leadership and Management focussed MSc from the University of Warwick. The programme is aligned to the Level 7 Senior Leader Master’s Degree Apprenticeship standard.
The three-year part-time programme combines workplace learning with block release study at WMG in eight one-week study modules, each followed by a work-based assignment plus a work-based project. The programme is made up of core and elective modules, giving participants the opportunity to develop specialisations of particular relevance to their current role and future career aspirations. It will lead to a University of Warwick MSc and a Degree Apprenticeship.
WMG was delighted to welcome Rick Snyder, Governor of the State of Michigan, on Friday (20 April 2018).
Our Academic Director, Professor Barbara Shollock introduced the Governor to WMG and gave an overview of our research capabilities and education programmes including those aimed at the next generation of young engineers and our executive education programmes.
The Governor was then given a tour of our world-class research and development facilities, including the International Manufacturing Centre. There, Professor Paul Jennings explained more about our Intelligent Vehicles research, including our state-of-the-art ‘3XD Simulator for Intelligent Vehicles.’ Professor Jennings also explained more about the UK Central CAV Testbed, a £25m project led by WMG which will see roads in Coventry and Birmingham become the UK testbed for developing the next generation connected and autonomous (CAV) vehicles. This was an area of particular interest as the University of Michigan is home to MCity, a demo ground built specifically for driverless car technology.
WMG, at the University of Warwick, is investing in data driven innovations with a new Centre for Applied Artificial Intelligence. The Centre will enable industry and business to leverage large volumes of digital information to gain competitive insights through Artificial Intelligence methods.
This new centre brings together several applied areas of activity where WMG has an established track record of excellence. It will support the continued expansion of existing research groups in response to the ever-changing landscape of UK industrial needs. Two new appointees, Professor Giovanni Montana and Professor Mehrdad Dianati, will spearhead the Centre working closely with other academic colleagues in Intelligent Vehicles, WMG Cyber Security Centre and the Institute of Digital Healthcare.