Cellulose "nanopaper" as building blocks for sustainable materials

Lead Research Organisation: Imperial College London
Department Name: Dept of Aeronautics

Abstract

Increasing energy cost, heavy legislative pressures, consumer's demand for environmental friendlier products, carbon neutral technologies and a sustainable future have all triggered fresh interest in research and development of green(er) materials. In this context, cellulose nanofibres are regarded as the prime candidate for the production of high performance sustainable composites. However, the high tensile stiffness (up to 160 GPa) and strength (at least 1 GPa) of a single cellulose nanofibre has yet to be fully exploited in composite materials. Numerous researchers have already manufactured bacterial cellulose (BC)- or nanofibrillated cellulose (NFC)-reinforced polymer composites. Whilst these studies showed the ability of nanocellulose to improve the mechanical performance of polymer matrices, many of these nanocomposites still performed worse than or only equally well compared to PLA, which is one of the highest performing bio-derived polymers that is commercially available at a reasonable price.

This proposed project aims to develop the next generation of nanocellulose-reinforced polymers applying green engineering principles to reduce the use of solvents and energy, as well as introduce simple manufacturing concepts to produce sustainable nanocomposites that are truly high performance for high volume structural applications. To achieve this, this project will concentrate on the use of: (i) ultra-low grammage or (ii) high performance cellulose "nanopapers" as the building blocks for sustainable composite materials. It can be anticipated that such truly green and high performance nanofibre composites will find wider applications for instance in the composite, plastic electronics and flexible display industries.

Planned Impact

The main beneficiaries of the proposed research will be the academic engineering science community and the UK/EU engineering, as well as industrial manufacturing base throughout the value chain, from materials suppliers to end users. The concepts explored in this proposed project are of fundamental interest to various industries including the composites and pulp and paper industries. A recent report by the Royal Society, "The Scientific Century" makes six recommendations around the long-term support and investment in science, including (i) put science and innovation at the heart for a strategy for long-term economic growth; (ii) prioritise investment in excellent people; (iii) strengthen government's use of science; (iv) reinforce the UK's position as a hub for global science and innovation; (v) better align science and innovation with global challenges, (vi) revitalise science and mathematics education. This project will focus on most, or if not all of these recommendations. As the manufacturing technology described in this project is as simple as making paper, it is cost-effective and easily scalable. This particular attribute appeals to UK's manufacturing industry, particularly the small and medium enterprises which do not have large amount of starting investment in manufacturing equipment. The know-how of nanopaper manufacturing and design procedures developed throughout the course of this project will be applicable to the area of materials engineering and technology, as well as fabrication of nanostructured materials. Whilst the current price for nanocellulose is still rather high, the successful outcome of this project will aid the commercialisation of nanocellulose products, where its relatively high cost can be justified by materials performance. Furthermore, this project will have major educational outcomes; it will provide research experience in novel manufacturing methods, materials testing and characterisation techniques, training in methodology and transferable skills for researchers working in complementary research areas. The successful funding of this project will train and educate the next generation of researchers in the area of composites manufacturing, in line with UK's composites strategy. Since this research is conducted in a university environment, the undergraduates will be exposed to materials driven research in a chemical engineering setting. The consumer and the wider society will also benefit as a whole, as the outcome of this project will include, for example, more environmentally friendlier materials through the use of greener starting materials, simpler manufacturing methods and reduced materials usage. The materials manufactured throughout this project will depend on the outcome but likely to provide an alternative to glass fibre-reinforced composites. Moreover, these materials also have the potential for reduced through-life cost, which the end users demand. To maximise the impact of the proposed project, the benefits of this research will be publicised to a much broader audience, capatilising on our societal needs for environmental friendly materials. Results will be disseminated at various international conferences and peer-reviewed publications. Where appropriate, commercially relevant materials will be protected by patent applications, which may be licensed or spun-out through UCL Business, the exploitation arm of UCL. A dedicated website will also be set up to further disseminate the outcome of this project to target the relatively narrow confines of academia. Here, UK and EU policy makers will have the chance to review, investigate and come up with new policies to drive the direction of sustainable composite materials.

Publications

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Fortea-Verdejo M (2017) Plant fibre-reinforced polymers: where do we stand in terms of tensile properties? in International Materials Reviews

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Hervy M (2018) Mechanical response of multi-layer bacterial cellulose nanopaper reinforced polylactide laminated composites in Composites Part A: Applied Science and Manufacturing

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Hervy M (2015) Life cycle assessment of nanocellulose-reinforced advanced fibre composites in Composites Science and Technology

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Mautner A (2018) Better together: synergy in nanocellulose blends. in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

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Shamsuddin S (2016) Ductile unidirectional continuous rayon fibre-reinforced hierarchical composites in Composites Part A: Applied Science and Manufacturing

 
Description Green composites using nanocellulose fibers as reinforcement promise a sustainable and renewable alternative to petroleum-based plastics. However, our study showed that nanocellulose-reinforced polymer composites might not be as green as initially thought as numerous waste are generated during the production of nanocellulose (both bacterial cellulose and wood-derived nanofibrillated cellulose), consumables used during composite manufacturing and the end of life of these composites.

We have also found that there is currently no standardised test methods for evaluating the tensile properties of nanocellulose network (also known as cellulose nanopapers). With the funding of this grant, we have shown that the measured tensile properties of cellulose nanopapers is highly dependent on the test specimen geometries used. In addition to this, our work also elucidated the importance of an independent strain measurement system (e.g. a non-contact video extensometer) to evaluate the Young's modulus of these cellulose nanopapers. We also develop (one of the first) fracture resistance test of cellulose nanopapers.

With these standardised test method, we have now shown that it is possible to produce high performance cellulose nanopapers, which can be used directly as the reinforcement for polymer in a laminated architecture to produce truly sustainable and high performance composites. In addition to this, we have also shown that we could reduce the grammage of these cellulose nanopapers (to 5 gsm) and use these ultra-low grammage cellulose nanopapapers as reinforcement for polymers in a laminated architecture. Whilst the final composite properties reinforced with these ultra-low grammage nanoappers did not differ much compared to high grammage (60 gsm) nanopaper-reinofrced polymers, the use of ultra-low grammage nanopapers as the reinforcement has the advantage of reduced production time.

We have also shown that highly porous cellulose nanopapers can be produced by changing the dispersing medium for the nanocellulose prior to nanopaper production. With such porous nanocellulose network, we showed that these network can be impregnated at a single fibre level to fully exploited the high tensile stiffness and strength of a single cellulose nanofibre.
Exploitation Route We think that the green credentials of nanocellulose-reinforced composites will now be taken into account when discussing about the possibility of producing greener materials from nanocellulose.

The wider audience will also think about the environmental impact associated with the manufacturing of these composites and hopefully, they will find better manufacturing methods that will place a lighter (or zero) environmental burden.

On the test specimen geometry work, we believe that the nanocellulose community will now use our work as a reference for the tensile testing (and fracture testing) of their manufactured cellulose nanopapers. This is a significant step forward towards a standardised test methods for cellulose nanopapers.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Chemicals,Environment,Manufacturing, including Industrial Biotechology

URL http://www.imperial.ac.uk/future-materials-group/publications/
 
Description With the funding of this grant, we were able to show using lifecycle analysis that sustainable nanocellulose-reinforced polymer composites may not be as green as initially thought, especially when the manufacturing process is taken into account. This has led to a journal article publication (CSTE 2015, 118, 154), as well as a web publication about this work (http://www.materialstoday.com/composites/news/how-green-are-celluose-reinforced-composites/). Some of the findings from this grant has been picked up by the scientific magazine, Impact, which is an open access scientific report. They are currently working on an article about the findings on this grant (the article will be open access as well).
First Year Of Impact 2015
Sector Aerospace, Defence and Marine,Agriculture, Food and Drink,Environment,Manufacturing, including Industrial Biotechology
Impact Types Societal,Economic

 
Description Grow-Your-Own Composites: Programming Diverse Material Properties for Defence into Engineered Bacterial Cellulose
Amount £542,617 (GBP)
Funding ID EP/N026489/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2016 
End 06/2019
 
Description Optically Transparent Acrylic Composite Laminates Derived from Microbially-synthesised Nanofibres
Amount £80,000 (GBP)
Funding ID ACC 101658 
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 05/2017 
End 03/2018
 
Description Optically transparent armor reinforced with microbially-synthesized cellulose nanofibers with self-repair capability
Amount $250,000 (USD)
Organisation RDECOM (Research Development and Engineering Command US Army Chemical and Biological centre 
Sector Public
Country United States
Start 07/2019 
End 06/2022
 
Description Optically transparent armour v2.0: Impact-modified acrylic composites reinforced with hornified bacterial cellulose pellicles
Amount £125,000 (GBP)
Funding ID ACC500273 
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 07/2018 
End 12/2019
 
Description Studentship
Amount £72,000 (GBP)
Organisation Imperial College London 
Sector Academic/University
Country United Kingdom
Start 02/2015 
End 01/2018
 
Title Data for International Materials Review 
Description The data collected consist of all the tensile properties of natural fibre-reinforced polymer composites up to the year 2016, published in the journal International Materials Review 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact We showed in our published article (International Materials Review 2018, http://dx.doi.org/10.1080/09506608.2016.1271089) using these data that natural fibre reinforced polymers still cannot compete with glass fibre reinforced polymers. This shows that the statement "natural fibres are an alternative to glass fibres to produce equally high performance fibre reinforced composites" is not true. 
 
Title Tensile properties of cellulose nanopapers 
Description This is a data showing (up to the year 2016) the tensile properties of neat nanofibrillated cellulose and bacterial cellulose nanopapers. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact We found that the tensile properties of these nanopapers vary across research groups, countries and even continents. More importantly from these data, we found that there is no standardised test methods for these cellulose nanopapers. Various test specimen geometries have been used. Some authors used an independent strain measurement for Young's modulus calculation but many of them don't. This leads to us to conclude that not all the data published in literature on the tensile properties of cellulose nanopapers are trustworthy. Strain measurement is very important in determining the Young's modulus of any material, which many authors in this field seemed to have ignored. We have published results showing the importance of test specimen geometries and an independent strain measurement on the measured tensile properties of these nanopapers. 
 
Description Cellulose nanopapers with varying grammages 
Organisation Aalto University
Department School of Chemical Technology
Country Finland 
Sector Academic/University 
PI Contribution My research team has provided the research idea of producing cellulose nanopapers (both bacterial cellulose and wood-derived nanofibrillated cellulose) of different grammages. The hypothesis is that the lower the grammage, the more permeable the nanopapers will be. My research team has also provided the know-how on the manufacturing of cellulose nanopapers that we have developed and optimised over the past 5 years. The EPSRC grant also allowed us to purchase a micro-tensile tester to test the mechanical properties of these nanopapers.
Collaborator Contribution The partners provided the laboratory space to produce these nanopapers, as well as access charges to experimental facilities to quantify the properties of these papers. These include: Accupyc, Mercury Intrusion Porosimetry, Carbohydrate Analysis and scanning electron microscopy.
Impact We have shown that the mechanical performance of bacterial cellulose nanopapers is highly dependent on nanopaper grammage but this is not the case for nanofibrillated cellulose. We hypothesise that this is due to the presence of hemicellulose in nanofibrillated cellulose as it will fill the gaps between the nanofibres. A manuscript has been prepared to be submitted for publication. This work has also been presented in as an oral presentation in the 2015 International Conference for Composite Materials and as a poster in the 2015 Round Table of Ideas - Nanocellulose workshop in the University of Vienna.
Start Year 2015
 
Description Cellulose nanopapers with varying grammages 
Organisation University of Vienna
Country Austria 
Sector Academic/University 
PI Contribution My research team has provided the research idea of producing cellulose nanopapers (both bacterial cellulose and wood-derived nanofibrillated cellulose) of different grammages. The hypothesis is that the lower the grammage, the more permeable the nanopapers will be. My research team has also provided the know-how on the manufacturing of cellulose nanopapers that we have developed and optimised over the past 5 years. The EPSRC grant also allowed us to purchase a micro-tensile tester to test the mechanical properties of these nanopapers.
Collaborator Contribution The partners provided the laboratory space to produce these nanopapers, as well as access charges to experimental facilities to quantify the properties of these papers. These include: Accupyc, Mercury Intrusion Porosimetry, Carbohydrate Analysis and scanning electron microscopy.
Impact We have shown that the mechanical performance of bacterial cellulose nanopapers is highly dependent on nanopaper grammage but this is not the case for nanofibrillated cellulose. We hypothesise that this is due to the presence of hemicellulose in nanofibrillated cellulose as it will fill the gaps between the nanofibres. A manuscript has been prepared to be submitted for publication. This work has also been presented in as an oral presentation in the 2015 International Conference for Composite Materials and as a poster in the 2015 Round Table of Ideas - Nanocellulose workshop in the University of Vienna.
Start Year 2015
 
Description LCA of composite materials 
Organisation University College London
Department Chemical Engineering
Country United Kingdom 
Sector Academic/University 
PI Contribution We have developed a process flow diagram for the manufacturing of nanocellulose-reinforced epoxy composites and compared that against polylactide and glass fibre reinforced polypropylene composites. We have also provided the mechanical performance of these composites for subsequent lifecycle analysis.
Collaborator Contribution The partners have provided us with a lifecycle engineering software (GaBI) to model the environmental impact of these manufacturing processes.
Impact 'Green' composites using nanocellulose as reinforcement promise a sustainable and renewable alternative to petroleum-based plastics. However, no studies have yet been done to compare the green credentials of nanocellulose-reinforced composites against commercially available and widely used bio-based polymers (polylactide) and composites (glass fibre-reinforced polypropylene). Our study showed that nanocellulose (both bacterial cellulose and wood-derived nanofibrillated cellulose) reinforced epoxy composites might not be as green as initially thought. This was attributed to the energy consumption of deriving the raw materials for the biosynthesis of bacterial cellulose. In the case of wood-derived nanofibrillated cellulose, it is attributed to the energy consumption of grinding wood fibres into nanoscale cellulosic fibres. In addition to this, the manufacturing process of nanocellulose-reinforced epoxy utilising vacuum assisted resin infusion also places heavy environmental burden as various consumables are required for the process. Nevertheless, the green credentials of nanocellulose-reinforced epoxy composites can be improved by producing nanocellulose-reinforced epoxy composites with better mechanical performance that will utilise the high tensile stiffness and strength of single nanocellulsoe fibres. This collaboration is multi-disciplinary involving composite science and technology, and chemical engineering. This collaboration has led to a publication in the journal Composite Science and Technology (Hervy et al., Composites Science and Technology 118 (2015) 154). The collaboration date is earlier than the grant award date due to my move from UCL to Imperial College London, which delayed the start date of the grant.
Start Year 2014
 
Description Annual meeting of the American Chemical Society 2015 in Denver 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Two oral presentation were given; the first was on the application of nanocellulose as emulsifiers and the second was on the manufacturing of all-cellulose nanocomposites.
Year(s) Of Engagement Activity 2015
 
Description European Conference on Composite Materials 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact I gave a talk at one of the largest composites conference in Europe (~1000 attendees). About 70 people attended my talk on nanocellulose-based composite materials and how best to utilise nanocellulose. The audience and I had a very interesting discussion on where nanocellulose (and any other cellulose-based materials) should be heading.
Year(s) Of Engagement Activity 2016
 
Description Giving a research seminar - Lulea University of Technology 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact I was invited to give a talk at the research group of Kristiina Oksman in Lulea University of Technology. I had a tour of their facilities. This allowed us to identify areas that we could collaborate based on the facilities and technical expertise available. We had a couple of ideas on how to strengthen our research collaborations.
Year(s) Of Engagement Activity 2016
 
Description Giving a seminar at KTH 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact This was a seminar given at the Wallenberg Wood Science Centre at KTH, Sweden.

Approximately 30 people attended and this talk did spark questions and discussion (the talk was about the green credentials of nanocellulose).
Year(s) Of Engagement Activity 2015
 
Description Giving a seminar at the University of Exeter 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact I was invited to give a talk on the research outcome of this EPSRC grant. After the talk, the audience and myself actually had a very nice chat, not only on the science of what I have presented but also the background information that i did not present (basically the know-how). This allows the audience (mainly students) to avoid a lot of the trial and error mistakes we have made in the lab. In addition to this, the audience and I also discussed a lot about career as a young academic and what are the possible routes for them to get into academia.
Year(s) Of Engagement Activity 2016
URL http://emps.exeter.ac.uk/physics-astronomy/events/archive/
 
Description IAWPS 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact This was an invited talk in a conference. The work presented was on the application of cellulose nanopapers for composite applications.
Year(s) Of Engagement Activity 2015
 
Description International Conference on Composite Materials 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact It was an oral presentation on the lifecycle assessment of nanocellulose-reinforced polymer composites in the nanocellulose session of ICCM 2015. Approximately 50 attendees were in the session. My talk has sparked numerous questions and discussion as my talk has shown that nanocellulose might not be as green as we initially thought.
Year(s) Of Engagement Activity 2015
URL http://www.iccm20.org/fullpapers/file?f=LEk21zPAkR
 
Description International Symposium on Bioplastics, Biocomposites and Biorefining 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact I was invited to give a talk about sustainable materials in this conference. This conference is attended by approximately 200 people and we had a very interesting discussion about nanocellulose and their materials for sustainability.
Year(s) Of Engagement Activity 2016
URL http://isbbb.org/home
 
Description Lifecycle analysis of cellulose nanocomposites 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Materials Today wrote an article about a work that we have published (from this grant) in Composites Science and Technology (2015, 118, 154). This is an online article which has been shared (via social media).
Year(s) Of Engagement Activity 2015
URL http://www.materialstoday.com/composites/news/how-green-are-celluose-reinforced-composites/
 
Description Round Table of Ideas - Nanocellulose 2015 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact The first Round Table of Ideas - Nanocellulose 2015 was held between 26-28th September 2015, in the Faculty of Chemistry of the University of Vienna. This workshop was co-organised by Imperial College London (Dr Koon-Yang Lee), Institute of Materials Chemistry and Research (Prof Alexander BIsmarck, Dr Andreas Mautner), University of Manchester (Dr Jonny Blaker) and Aalto University (Prof Eero Kontturi). This workshop has attracted more than 80 participants from 20 different universities, research institutions and industries. Unlike conventional conference and workshops, whereby every attendees present their latest research, we have decided to take a different approach and organised the workshop into 4 different forums:

Professor Forum
Throughout a researcher's career, numerous ideas have been tested but many did not hold their promise. In our workshop, the Professors who have been actively working in the area of nanocellulose discussing not only the latest scientific achievements but also what had been achieved, as well as what research ideas had been tried out but did not make it to publications.
Young Academic Forum
In most conferences, young academics are reluctant to participate in the discussion. We believe that young and younger academics should participate in discussion as they are the next generation of researchers to lead the field. To promote this, the Young Academic Forum is a forum solely run by young researchers, including session chairing, time keeping and encouraging Q&A amongst the audience. This exposes young researchers and promote active knowledge transfer between researchers from various institutes.
Editor Forum
In the Editor Forum, we invited a panel of journal editors to discuss what do they look for in a manuscript before sending it out for review. This forum decypher the science behind editorial decisions, such as what do journal editors look for in the first instance, running manuscripts through plagarism software and what type of manuscript warrants a straight out rejection.
Knowledge Transfer Forum
We have experts from Anton Paar, Krüss and SMS providing an introduction to the theory behind the methods, tips & tricks in measuring and interpreting the surface properties of nanocellulose. Participants will also have the chance to experience these techniques hands-on. An event that is useful for all researchers.
Year(s) Of Engagement Activity 2015
URL http://www.imperial.ac.uk/materials-and-sustainability/impact-and-public-engagement/round-table-of-i...
 
Description Royal College of Art Exhibition 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact I partnered up with an Royal College of Art designer Yunting Lin (http://yuntinglin.com) to produce natural fibre preforms from nanocellulose. I provided my expertise in nanocellulose, as well as some nanocellulosic materials that we have produced in the lab to Yunting for the production of these preforms. We also conducted mechanical tests on the preforms he has manufactured to ascertain their mechanical performance. These set of data sped up the uptake of this material by the industry.
Year(s) Of Engagement Activity 2015
URL https://www.rca.ac.uk/students/yun-ting-lin/