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Properties and performance of regenerated cellulose thermoset biocomposites
University of Borås, Faculty of Textiles, Engineering and Business. (Resource recovery)
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Sustainable development
The content falls within the scope of Sustainable Development
Abstract [en]

Biocomposites have been developed to address the sustainability issues of nonrenewableresource based materials. These composites are often produced by reinforcing natural fibres in petroleum based thermoset resins or thermoplastic polymers. Thermoplastic polymers from renewable resources are commercially available, whereas thermoset resins are predominantly derived from crude oil resources. Cellulose fibres have significant importance and potential for polymer reinforcement in lightweight composites. Natural fibres are chemically diverse and their properties vary largely which makes it difficult for them to be used in several applications. The natural fibre based products are limited by their characteristic odour emissions. These issues of natural fibres can be addressed by partly manmade fibres i.e. regenerated cellulose fibre which with little or no compromise in the environmental benefits of the natural fibres can be produced from biomass origin. Natural fibres and their composites have been observed and researched closely for many decades. Study of regenerated cellulose fibres and their composites is, on the other hand, relatively new. Regenerated cellulose fibres are prospective reinforcing material in the composite field due to their even quality and high purity. These fibres have good mechanical properties and also address the odour emission issue of the natural fibres. The development of biocomposites from regenerated cellulose fibre and thermoset resin synthesized from renewable resources has therefore been viewed with considerable interest.

This thesis describes the development of biocomposites from regenerated cellulose fibres (lyocell and viscose) and thermoset resins synthesized from renewable resources (soybean oil and lactic acid). The performance and the properties of the composites were evaluated. Chemical surface treatments, alkali and silane, were performed on the fibres in order to improve the performance of the composites. Hybrid composites were also produced by mixing of two types of reinforcement in order to complement one type of fibre with other. The developed composites were evaluated through mechanical, thermal, viscoelastic and morphological properties among others. The results showed that the regenerated cellulose fibre thermoset biocomposites have reasonably good properties. Fibres before and after treatment were studied in detail. The silane treatment on these fibres improved the mechanical properties of the composites as the silane molecules act as a link between the fibre and resin which gives the molecular continuity across the interface region of the composite.

Place, publisher, year, edition, pages
Borås: Högskolan i Borås, 2015. , p. 49
Series
Skrifter från Högskolan i Borås, ISSN 0280-381X ; 57
Keywords [en]
regenerated cellulose fibres, surface modification, alkali, silane, mechanical analysis, biocomposites, renewable resources
National Category
Environmental Biotechnology
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-26ISBN: 978-91-87525-43-8 (print)ISBN: 978-91-87525-44-5 (print)OAI: oai:DiVA.org:hb-26DiVA, id: diva2:793915
Public defence
2015-06-12, D207, University of Borås, Allégatan 1, Borås, 10:00 (English)
Opponent
Available from: 2015-05-19 Created: 2015-03-09 Last updated: 2015-12-18Bibliographically approved
List of papers
1. Effect of water absorption on mechanical properties of soybean oil thermosets reinforced with natural fibers
Open this publication in new window or tab >>Effect of water absorption on mechanical properties of soybean oil thermosets reinforced with natural fibers
2012 (English)In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 31, no 18, p. 1191-1200Article in journal (Refereed) Published
Abstract [en]

Natural fiber composites are known to absorb more water than glass fiber reinforced composites. In this study, hybrid natural fiber composites were prepared by combining different fiber reinforcements, and both the water absorption and the mechanical properties were studied. Compression molding technique was used to manufacture composite laminates from a bio-based resin (acrylated epoxidized soybean oil) and natural fibers: non-woven and woven jute, non-woven regenerated cellulose mat (Lyocell and viscose), and woven glass fiber. The composite laminates were cured at 160–170 C and 40 bar, with a fiber content of 40 wt%. We investigated effect of pretreatment of regenerated cellulose fiber using 4% NaOH solution. The gravimetric water absorption was tested by exposure to water for 10 days. Specimens were cut from composites with laser-cutting technique according to ISO standards, and tested for tensile, flexural, and impact strength. To determine the influence of water absorption on the mechanical properties, specimens were immersed in distilled water for 10 days before testing. As a reference, dry specimens were tested. The results showed that water absorption was reduced by producing hybrid composites with jute fibers, glass fiber, and Lyocell fiber. The tensile, flexural, and impact properties were improved by inclusion of glass fiber and Lyocell in the composite. The tensile and flexural properties of natural fiber reinforced composites were mostly affected by the influence of water, but this was improved considerably by hybridization with glass and Lyocell fibers. The viscoelastic properties of the manufactured composites and hybrid composites were studied using dynamic mechanical thermal analysis.

Place, publisher, year, edition, pages
Sage Publications Ltd., 2012
Keywords
Soybean oil, thermoset, composite, regenerated cellulose, Resursåtervinning
National Category
Materials Engineering
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1484 (URN)10.1177/0731684412455257 (DOI)000307722800001 ()2320/11916 (Local ID)2320/11916 (Archive number)2320/11916 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-10-31Bibliographically approved
2. Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin
Open this publication in new window or tab >>Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin
2015 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed) Published
Abstract [en]

The effect of surface treatments, silane and alkali, on regenerated cellulose fibers was studied by using the treated fibers as reinforcement in lactic acid thermoset bioresin. The surface treatments were performed to improve the physico–chemical interactions at the fiber–matrix interface. Tensile, flexural and impact tests were used as indicator of the improvement of the interfacial strength. Furthermore, thermal conductivity, viscoelasticity measurements as well as microscopy images were made to characterize the fiber surface treatments and the effect on adhesion to the matrix. The results showed that silane treatment improved the mechanical properties of the composites as the silane molecule acts as link between the cellulose fiber and the resin (the fiber bonds with siloxane bridge while the resin bonds with organofunctional group of the bi-functional silane molecule) which gives molecular continuity in the interphase of the composite. Porosity volume decreased significantly on silane treatment due to improved interface and interlocking between fiber and matrix. Decrease in water absorption and increase in contact angle confirmed the change in the hydrophilicity of the composites. The storage modulus increased when the reinforcements were treated with silane whereas the damping intensity decreased for the same composites indicating a better adhesion between fiber and matrix on silane treatment. Thermogravimetric analysis indicated that the thermal stability of the reinforcement altered after treatments. The resin curing was followed using differential scanning calorimetry and the necessity for post-curing was recommended. Finite element analysis was used to predict the thermal behavior of the composites and a non-destructive resonance analysis was performed to ratify the modulus obtained from tensile testing. The changes were also seen on composites reinforced with alkali treated fiber. Microscopy images confirmed the good adhesion between the silane treated fibers and the resin at the interface.

Keywords
surface modification, cellulose fiber, mechanical properties, thermal conductivity, finite element analysis, resonance analysis
National Category
Polymer Technologies Composite Science and Engineering Textile, Rubber and Polymeric Materials Paper, Pulp and Fiber Technology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-70 (URN)10.1007/s10570-015-0643-x (DOI)
Funder
ÅForsk (Ångpanneföreningen's Foundation for Research and Development)
Available from: 2015-05-20 Created: 2015-05-20 Last updated: 2017-12-04Bibliographically approved
3. Properties of green composites with regenerated cellulose fiber and soybean-based thermoset for technical applications
Open this publication in new window or tab >>Properties of green composites with regenerated cellulose fiber and soybean-based thermoset for technical applications
Show others...
2014 (English)In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 33, no 2, p. 193-201Article in journal (Refereed)
Abstract [en]

Composites were developed by reinforcing available non-woven Lyocell and viscose in acrylated epoxidized soybean oil (AESO). Compression molding was used to make composites with 40–60 wt% fiber content. The fiber content comprises only Lyocell or viscose fiber, or mixture of these fibers in known ratio. Hybrid composites were made by a mixture of both the fibers in known ratio and it affects the properties. The effect of hybridization was evident in most tests which gives us an opportunity to tailor the properties according to requirement. Lyocell fiber reinforced composites with 60 wt% fiber content had a tensile strength and modulus of about 135 MPa and 17 GPa, respectively. Dynamic mechanical analysis showed that the Lyocell fiber reinforced composites had good viscoelastic properties. The viscose fiber reinforced composites had the high percentage elongation and also showed relatively good impact strength and flexural modulus. Good fiber-matrix adhesion reflected in mechanical properties. SEM images were made to see the fiber-matrix compatibility.

Place, publisher, year, edition, pages
SAGE, 2014
Keywords
Biocomposites, Regenerated Cellulose, Mechanical properties, Viscoelastic Properties, Resource Recovery, Polymer Technology
National Category
Materials Engineering
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1653 (URN)10.1177/0731684413504325 (DOI)000329961500007 ()2320/12943 (Local ID)2320/12943 (Archive number)2320/12943 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01
4. Reusing Textile Waste As Reinforcements In Composites
Open this publication in new window or tab >>Reusing Textile Waste As Reinforcements In Composites
2014 (English)In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 17, p. 1-16Article in journal (Refereed) Published
Abstract [en]

Polyester (PET) has wide applications in textile industries as textile fiber and its share continues to grow. Substantial quantities of cotton/polyester blend fabrics are disposed every year due to technical challenges, which pose a big environmental and waste-dumping problem. The aim of this study is to evaluate the potential of discarded cotton/PET fabrics as raw materials for composites. If their inherent reinforcement properties can be used in composites, an ecological footprint issue can be solved. In this study, we investigate three concepts for reuse of cotton/PET fabrics for composites: compression molding above the Tm of PETs, use of a matrix derived from renewable soybean oil, use of thermoplastic copolyester/polyester bi-component fibers as matrix. All three concepts have been explored to make them available for wider applications. The effects of processing parameters such as compression temperature, time and pressure are considered in all three cases. The third concept gives the most appealing properties, which combine good tensile properties with toughness; more than four times better tensile strength than the first concept; and 2.2 times better than the second concept.

Place, publisher, year, edition, pages
Wiley, 2014
Keywords
Composites, Mechanical properties, Recycling, Textiles, composites, textiles, biocomposite
National Category
Polymer Chemistry Other Environmental Engineering
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1941 (URN)10.1002/app.40687 (DOI)000337623000023 ()2320/14395 (Local ID)2320/14395 (Archive number)2320/14395 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-11-08Bibliographically approved
5. Effect of alkali and silane surface treatments on regenerated cellulose fibre type (Lyocell) intended for composites
Open this publication in new window or tab >>Effect of alkali and silane surface treatments on regenerated cellulose fibre type (Lyocell) intended for composites
2014 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1Article in journal (Refereed) Published
Abstract [en]

Cellulose fibres have significant importance and potential for polymer reinforcement. It is essential to modify the surface of the fibre to obtain good fibre-matrix interface. Surface treatments can increase surface roughness of the fibre, change its chemical composition and introduce new moieties that can effectively interlock with the matrix, resulting in good mechanical properties in the composites. This is mainly due to improved fibre-matrix adhesion. The treatments may also reduce the water absorption rate by converting part of the hydroxyl groups on the fibre surface into other functional groups. Chemical modification of the surface of a regenerated cellulose fibre of the Lyocell type was carried out by alkali and silane treatments, which significantly changed the properties of the Lyocell fibres. Three parameters were considered when the fibre surface treatment was done: concentration (2–15 wt%), temperature (25 and 50 C) and time (30 min–72 h). Fourier transform infrared spectroscopy and Raman spectroscopy were used for chemical analysis and qualitative analysis of the cellulose crystallinity due to the surface treatments; subsequently, mechanical strength of the fibres was tested by tensile testing. Weight loss, moisture regain and swelling measurements were taken before and after treatments, which showed the obvious changes in fibre properties on treatment. Heat capacity of the fibres was measured for untreated and treated fibres, and thermal degradation of fibres was examined to see the stability of fibres at elevated temperatures. Wettability and surface energies were measured using dynamic contact angle method in three wetting mediums. Scanning electron microscopy was used to study the morphological properties of the fibres.

Place, publisher, year, edition, pages
Springer, 2014
Keywords
Cellulose, fibres, Lyocell, Alkali, Silane, Surface modification, Fiber surface treatment
National Category
Polymer Chemistry
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1981 (URN)10.1007/s10570-014-0526-6 (DOI)2320/14499 (Local ID)2320/14499 (Archive number)2320/14499 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-11-08Bibliographically approved

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Ramamoorthy, Sunil Kumar

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