Unravelling Polymers

The Definitive Blog on Polymers by Poly Fluoro Ltd.

Polymers in Ventilators

Few crises have galvanised the industrial world in the way that the current Covid-19 pandemic has done. As more was known about the illness, countries across the world became aware that their capacities for and inventories of key medical equipment was sorely lacking. While face masks and PPE equipment have been relatively easy to scale up quickly, the more high-end and complex medical equipment has required an even larger push to ensure we have the numbers needed to confront the situation at hand.

With urgency being the need of the hour, the manufacture of ventilators has spiked across the world. In India, the government has approached various private contract manufacturers to divert capacity to the manufacture of ventilators. A plan to build a moving, railway hospital with 20,000 beds is said to be materialising, while key states have set up Covid-centric hospitals to ensure that they have sufficient capacity. Considering that roughly 5% of cases end up requiring hospitalisation, the demand for ventilators is, at present, insatiable. 

High-performance polymers have always been at the forefront of medical device manufacturing. Recently, both PEEK and PPSU have gained some attention for their application on ventilator manufacture.

Here we look at some of the key properties of these polymers and how they lend themselves to the manufacture of ventilators and other medical devices.

  1. Biocompatibility – different readily available grades in PEEK and PPSU offer biocompatibility. However, it should be noted that biocompatibility varies. Some medical grades are acceptable for use only in equipment and devices that will not come in contact with human skin. Still more specialised grades are suitable for human contact, while the most high-end grades might be used inside the body.

  2. FAD approval – most graded of PEEK, PPSU, PTFE, and even PVDF come pre-approved by the FDA. This means that for some medical applications, no further certification may even be needed. It is beneficial in a time like this, where the need to fast-track development is key.

  3. Low particle discharge – one of the key requirements of a material that is used in the medical space is that it needs to exhibit minimal particle discharge. It is common for many filled grades of polymers to exhibit high levels of discharge. This discharge can settle in other areas of the equipment and cause both mechanical and electrical problems within the device. Furthermore, for respirator devices, the chance of particles entering the human lung would be very detrimental indeed!
    Both PEEK and PPSU are known for being very stable in this regard. Data released by NASA shows that the total percentage of mass lost over the lifetime of the part is only 1.1% and 0.3% for PPSU and PEEK, respectively.

  4. Flammability – most polymers, including PEEK and PPSU conform to at least a V-0 rating on flammability, meaning that even with the application of a flame, the material will self-extinguish within 10 seconds once the flame is removed. This is a critical feature from the point of view of safety.

  5. Mechanical strength – aside from the chemical and medical compatibility, both PEEK and PPSU exhibit superior mechanical strength. PEEK has one of the highest tensile strengths among polymers. As a result, the loads and wear that the parts are able to take are unparalleled and yield a long-lasting solution.

  6. Machinability – once of the key issues during the pandemic has been time-to-market. There is very little time to engage in extensive R&D and even trials need to be conducted with a very quick turnaround in mind. The fact that PEEK and PPSU can be machined, moulded, and even 3D printed makes their application that much more beneficial to the current climate. While initial prototyping can be done using 3D printing or machining, the production can gradually shift to moulding once the dimensions are frozen and the mould is developed. Since mould development can sometimes take weeks, the machinability of PEEK and PPSU serves as an intermediary measure to ensure that parts are supplied in the short term.

There are a host of polymer solutions available in addition to PEEK and PPSU. As things proceed, there is no doubt these too will find their uses. Such is the nature of the pandemic that new applications, advantages, and properties are constantly being discovered.

Solar Tracker Bearings - A Key Component in Renewable Energy

While the Covid 19 pandemic has caused deep pains across many industries, the world has been careful not to ignore the ever-present threat of global warming. Indeed, with the advent of the coronavirus, many nations have looked towards the renewable energy sector as a magic bullet. Not only do investments in renewable energy allow for a boost in economic activity, but the move away from fossil fuel-based power sources ensures that we continue to aim for the reduction in emissions that remain so vital to our planet’s future.

Some nations, such as Spain, have set aggressive targets for themselves, stating that by 2050 they will be 100% based on renewable energy. Others, such as the UK, have already started setting domestic records for the number of days in which coal-based power has not been required. India has also pledged to move towards solar energy, with many of the projects running well ahead of schedule. Recently, the Adani Group has been awarded the largest such contract on record, underlining the seriousness with which the government is approaching renewable energy.

At Poly Fluoro, we have delved deep into the renewables sector through our involvement in solar tracker bearings. We engaged in the first of such projects in mid-2018, when the industry was still ramping up and when new technologies were only just being understood. The learnings we have uncovered have allowed us to further invest and develop our own polymer technologies, with the aim that we are positioned to take on any project and offer the technical support and guidance needed by our clients.

Before we go into these learnings, let us first understand the purpose of the solar tracker bearing.

For all solar projects, the efficiency of the system is maximised when the installed panels are able to maximise their harvest of the sun’s radiation. Since the sun moves across the sky, the angle of the panels needs to alter as the day progresses. To facilitate this, a tracker is installed, which rotates the panels at the required rate. Since the tracker itself consumes power, it is vital to ensure that the energy expended in rotating the panels does not exceed the extra power generated by this system. It is for this reason that a smooth functioning bearing is essential. The solar tracker bearing clamps around the square tube on which the panels are fixed. The tracker rotates the square tube and the bearing’s job is to allow for this rotation with minimal friction.

Some of our key learnings are as follows:

  1. Size

    For the most part, a solar tracker bearing needs to match the size of standard square tubes. Since most projects would prefer to use off-the-shelf square tube dimensions, the bearings need to be designed accordingly.

    In India, the sizes of 75mm, 100mm, 120mm, and 150mm would be most common. Here too, the preference is for 100mm tubes, as this maximises the number of panels that can be installed on a single length of tube, but minimises on the weight of the tube itself.

    Our designs have focussed on creating a uniform bearing for the 100 square tube. In doing so, we have studied the dimensions of existing bearings to understand how much load and friction the part would be submitted to.

  2. Composition

    Our experience has shown that while erstwhile bearings demand the use of UHMWPE for solar tracker bearings, this polymer becomes problematic as volumes increase. The main reason is that UHMWPE is not injection mouldable. This means that parts need to be machined. Machining is time consuming, expensive, and it also results in a very heavy final component.

    Other candidates include POM (Polyacetal), HDPE, and Nylons. Each of these has advantages, although our preference has been towards POM, as it offers both strength and an ease of moulding. While HDPE is lightweight, it is not nearly as strong as POM. Nylon is the least preferred because it tends to swell when there is moisture. While Nylon bearings may have done well in projects where the climate is dry, the use of Nylon in more humid conditions would not be advisable.

    Other than the polymer, the key lies in what additives one incorporates. There are three primary factors to consider. The first is strength – which is managed by the choice of polymer. A typical solar tracker bearing of 100 square would need to accommodate at least 1000-1500 Kgs of vertical load. The second criterion is friction. The use of friction reducing additives is required in making solar tracker bearings, as it greatly enhances efficiency. Experience has shown us that there is a balance needed here. Too little friction can also be a bad thing, as it may cause the panels to rotate due to wind loads. Finally, the bearing needs to be UV resistant. Poly Fluoro has explored the impact of different fillers on UV resistance. While many manufacturers simply add carbon black and claim that the part is resistant to UV, this can be misleading. Our own research shows that the addition of black pigment can only withstand UV up to a point. In most cases, the bearing will begin to deteriorate within 2-3 years. The more expensive option is to use HALS (Hindered amine light stabilizers), which work by ensuring that the UV radiation is managed within the first 0.1mm of the part’s surface. HALS would allow the solar tracker bearing to have a life of 25-30 years, which is what is required when considering a solar project.

  3. Design

    While smaller projects may opt for machining, it is our belief that an injection moulded part is most suitable for solar tracker bearings.

    Using a special honeycomb or lattice structure, the bearings can be made lightweight, but strong enough to take heavy loads. Furthermore, with a cycle time of only under two minutes, the manufacture of a solar tracker bearing can be done in a fraction of the time it would take to machine the bearing from a rod or sheet.

    The combined impact of the weight reduction and lower cycle time results in a cost saving of over 50% in some cases. For large projects, where tens of thousands of bearings are needed, the machining route is both financially wasteful and unlikely to meet any stringent project timelines.

We hope the above information has been useful in better understanding the structure of the solar tracker bearing. As projects grow in size, we expect to come across more learnings. In the meantime, Poly Fluoro is proud to be one of the pioneers in this space. Our library of solar tracker bearings allows us to take on projects of different sizes and volumes, while offering both a quality product and a genuine academic understanding of the engineering behind it.

Covid 19 - A Boon for the Polymer Industry?

There has scarcely been a time as uncertain as this in the life of any working professional. Whether you are a salaried employee or a businessman, there is no doubt that the current pandemic has caused more than its fair share of sleepless nights. As companies scramble to get back on their feet, they are confronted with a perfect storm of dwindling order books, broken supply chains, and a cash flow crisis like never before. As a result, even companies with relatively strong order pipelines are finding it hard to source raw materials and maintain credit terms with suppliers who may – either due to caution or desperation – need their payments up front.

Manufacturing is no exception to all this, although the impact across the sector has been uneven. While those catering to non-essential products have been hit hard, manufacturers in essential areas have continued to have enough business to at least keep the lights on. That this alone needs to be viewed as a victory in these times tells us the extent of the difficulty. Nonetheless, the rise in certain essential industries along with the indication of where economic activity may be headed once the pandemic subsides should offer manufacturers a road map in terms of where to focus their efforts.

The polymer industry, which has traditionally been naturally diversified across many end-applications, may be well poised to step in and reap the benefits from a world trying rapidly to re-invent itself. Here we look at just a few industries which are evolving and using more polymers as they do.

  1. Automotive

    Although it is sad to say, there is little hope that the automotive sector as we know it will ever regain its earlier shine. Even before the pandemic, auto was in the doldrums, as consumers opted away from car ownership, or held off purchases of traditional fuel-based vehicles for the promise shown by electric vehicles.

    It is difficult to see – given the levels of unemployment, work-from-home directives, and extreme job uncertainty – why anyone would be thinking of buying a motor vehicle at this time or any time in the next four to six months at least. What this might spell for the industry is presently catastrophic.

    However, it is not all glum. The farm sector has seen some activity, as this is one area that has been forced to stay open throughout the lockdown. Farm equipment and vehicle manufacture has kept pace even during the slowdown and will most likely survive. Further, there is – for now at least – little threat of an electric vehicle onslaught on farming.

    Consequently, companies that are able to pivot and remain relevant in the electric vehicle space would survive in the long term. Again, even sales of EV are likely to be highly subdued for the next few quarters, but there is little doubt that companies steeped in combustion engine manufacturing need to start stepping out and engaging in R&D for EVs.

    For polymers, the opportunity remains to offer light-weight, durable solutions to improve efficiencies and performance. Wherein traditional automotive parts would focus on wear resistance and performance under high load and temperatures, the new engineering focusses on insulation, self-lubrication, and high strength-to-weight ratios. As it happens, polymers check all these boxes.

    Key products: Polymer seals, PTFE insulation films, PTFE-Bronze bands for shock absorber struts, Machined parts in PEEK and POM (Polyacetal), injection moulded polymer parts.
     

  2. Medical

    For obvious reasons, the medical industry has been one of the few to have survived the pandemic. Although there has been a massive toll – both financially and emotionally – on hospitals and medical workers, the pharmaceutical industry and medical device manufacturers have struggled to keep with demand.

    Polymers find multiple applications in the medical field. As the demand for certain devices – such as ventilators – has spiked, OEMs are looking for cheaper, better ways to keep pace with demand, while retaining the effectiveness of their products. Being chemically inert and often pre-FDA approved, polymers lend themselves faster to R&D.

    Similarly, in applications such as clean rooms and laboratories, polymer sealing materials are preferred as their behaviour to chemicals is already known.

    Finally, the demand for membranes has continued to spike, as manufacturers struggle to find novel ways to make masks and other personal protective equipment (PPE). ePTFE membranes have pore sizes slightly smaller than the droplets which carry the virus. In addition to this, they are hydrophobic, meaning that droplets do not adhere to their surfaces. This makes ePTFE an ideal venting material for masks.

    Key products: Polymer valves, customized polymer components - both machined and moulded, ePTFE (expanded PTFE) sealing tapes, ePTFE (expanded PTFE) membranes, PTFE tubes.
     

  3. Water

    As an essential service, water has operated through the pandemic and is an industry poised to keep benefiting from as cities expand and existing water sources become scarce. The future of freshwater may depend heavily on desalination plants, which would need waterways and pipelines to connect them to the water supply of cities.

    Again, due to their inert nature, polymers are well placed to benefit from the surge of activity expected in this sector. Polymer parts, seals, sealing tapes, and tubes are ideal for applications involving both freshwater and saltwater. The corrosive nature of saltwater and the effluents arising from desalination and water treatment mean that metal can never perform as effectively as polymers.

    Key products: PTFE Tubes, PTFE pipe lining, PTFE pipe support bearings, Polymer seals, Polymer valves, ePTFE Gasket Tapes
     

  4. Renewable Energy

    Even before the pandemic, the urgency for shifting to renewables was at an all time high. Countries that have agreed to the Paris Climate Agreement all accept that without a near-total shift into renewable energy, the global climate crisis cannot be averted. With this in mind, companies in the renewable energy industry have been pushing manufacturers to come up with novel, cost-effective, and workable solutions to be used across the spectrum of applications in renewables.

    It is for this reason that we have seen a huge amount of development for self-lubricating polymer parts in wind turbines, moulded polymer parts for solar applications, and high performance sealing materials in hydro-electric applications.

    Everyone agrees that renewables are here to stay. With polymers having a huge part to play in this sector, we may see a rapid offtake in the years to come.

    Key products: Solar Tracker Bearings, PTFE sliding bearings, Machined polymer insulator blocks, PTFE Seals, ePTFE (expanded PTFE) gasket tapes.