Two different types of natural fibers (jute and sisal) were studied and characterized, using optical microscopy, pycnometry density, single filament and linear density tests. Jute fibers were processed into composite parts from woven fabrics raw-material and sisal fibers were also processed into final composite componentes but in the form of chopped mat. Those fibers were used to reinforce polyester and epoxy matrices and therefore produce composite plates by resin infusion molding. Finally, the final obtained composite plates were submitted to mechanical testing, in order to assess their relevant mechanical properties.Fundação para a Ciência e a Tecnologia (FCT

Castro, B. F.

Duro, A. C.

Nunes, J. P.

Oliveira, Luís

Silva, J. F.

Universidade do Minho: RepositoriUM

 1
ST
 INTERNATIONAL CONFERENCE ON NATURAL FIBERS 
1
ST
 ICNF – Future Materials for Advance Applications  1 
DEVELOPMENT AND ASSESSMENT TO ENVIRONMENTALLY FRIENDLY 
NATURAL FIBER COMPOSITES 
 
 
J. P. Nunes1(*), B. F. Castro2, A. C. Duro3, , J. F. Silva2, L. Oliveira4  
1
 Institute of Polymers and Composites/I3N, Minho University, 4800-058 Guimaraes, Portugal 
2
 Department of Mechanical Engineering ISEP, 4200-072 Porto, Portugal 
3
 Department of Polymer Engineering, Minho University, 4800-058 Guimaraes, Portugal 
4
 PIEP - Pole for Innovation in Polymer Engineering, Minho University, 4800-058 Guimaraes, Portugal 
 (*)Email: jpn@dep.uminho.pt  
 
ABSTRACT 
Two different types of natural fibers (jute and sisal) were studied and characterized, using 
optical microscopy, pycnometry density, single filament and linear density tests. Jute fibers 
were processed into composite parts from woven fabrics raw-material and sisal fibers were 
also processed into final composite components but in the form of chopped mat. Those fibers 
were used to reinforce polyester and epoxy matrices and therefore produce composite plates 
by resin infusion molding. Finally, the final obtained composite plates were submitted to 
mechanical testing, in order to assess their relevant mechanical properties. 
 
INTRODUCTION 
During the past few decades, polymer matrix composites replaced, advantageously, many 
conventional materials, in various applications. This was possible because these materials 
have low density, excellent mechanical behavior and can be easily processed. The large 
majority of composite structures still use thermosetting matrices, like polyester or epoxy 
systems, even if, more recently, thermoplastic matrices are starting to be studied. (Mazumbar, 
2012, Nunes, 2003). 
Recently, because of their interesting properties, natural fibers are being studied as 
reinforcement material in composite components. Usually they are low-costly, combine very 
low density with high specific properties, are biodegradable and nonabrasive, unlike other 
reinforcing fibers and also readily available (Saheb, 1999). 
 
RAW MATERIALS AND COMPOSITE PROCESSING 
Jute and sisal fibers, chosen to be studied in this work, are between the most successfully used 
natural fibers as reinforcements in composite structures. The different natural fibers were 
impregnated and consolidated with two different thermoplastic resins: one orthophthalic 
polyester resin and one epoxy. 
Fibers were impregnated, at room temperature, by hand lay-up, with polyester and epoxy 
resins. Then, vacuum molding was employed to allow establishing a controlled consolidation 
pressure. 
 
RESULTS 
Microscopy obtained images are depicted in figure 2. 
Fiber characterization results are summarized in tables 1 and 2. 
Guimarães/Portugal, 09-11 June 2013 
Editor:  R. Fangueiro 2 
   
a) Jute fiber (50×)                                     b)  Sisal fiber (100×)                                c)  Sisal fiber (100×) 
Fig. 2. Typical jute and sisal fiber geometries. Sisal fibers have two typical shapes, shown in pictures b) and c) 
 
            Table 1 Sisal single filament test results                         Table 2 Jute plain woven fabric specifications 
Gage 
length 
Deformation 
at break 
Tensile 
strength 
Tensile 
modulus 
(mm) (%) (MPa) (GPa) 
20,00 3,22±0,28 760±114 28,1±0,97 
25,00 2,81±0,70 763±9,2 19,4±0,66 
30,00 2,64±0,42 461±185 14,7±0,13 
 
 
Mass (g/m
2
) 204.0±7.0 
Warp 
Linear density of the yarn (Tex) 140.5±9.5 
Density (yarns/cm) 7.0±0.1 
Crimp (%) 5.04±0.89 
Weft 
Linear density of the yarn (Tex) 142.6±19.1 
Density (yarns/cm) 6.6±0.5 
Crimp (%) 2.44±1.24 
Mechanical test results, for polyester matrix composites are summarized in table 3. 
Table 3 Mechanical test results of jute and sisal polyester matrix composites 
 
Fiber type 
Strength 
(MPa) 
Elasticity modulus 
(GPa) 
Deformation at break 
(%) 
Tensile 
Jute 57,0±7,2 7,0±0,5 1,9±0,2 
Sisal 24,8±3,9 5,4±0,3 1,5±0,3 
Flexural 
Jute 91,5±3,8 5,9±0,2 2,8±0,1 
Sisal 54,8±1,9 3,9±0,2 2,4±0,1 
 
Acknowledgements 
The authors wish to thank the Engineering School ofthe University of Minho, PIEP – Pole for 
Innovation in Polymer Engineering and the School of Engineering of the Polytechnic of 
Porto, for the support given to this work. They also acknowledge the Portuguese Foundation 
for Science and Technology for the financial support of IPC through project PEst-
C/CTM/LA0025/2013 (Strategic Project - LA 25 - 2013-2014).  
 
REFERENCES 
1. Nunes, J. P., Silva, J. F., van Hattum, F.W. J., Bernardo, C. A., Marques, A. T., Brito, A. M. 
and Pouzada, A. S., “Production of thermoplastic towpregs and towpreg-based composites” in 
Polymer Composites – From Nano- to Macro-Scale, Eds K. Friedrich, S. Fakirov and Z. 
Zhang, Eds Kluwer Academic Publishers, 2005. 
2. Sanjay Mazumdar “Growth opportunities: materials innovation will drive composites usage to 
new heights”. High Performance Composites, May 2012. 
3. D. Nabi Saheb and J. P. Jog “Natural fiber polymer composites: A review” Advances in 
Polymer Technology, Vol. 18, No. 4, pp. 351–363 1999. 


English

Development and assessment to environmentally friendly natural fiber composites

 1ST INTERNATIONAL CONFERENCE ON NATURAL FIBERS 1ST ICNF – Future Materials for Advance Applications  1 DEVELOPMENT AND ASSESSMENT TO ENVIRONMENTALLY FRIENDLY NATURAL FIBER COMPOSITES   J. P. Nunes1(*), B. F. Castro2, A. C. Duro3, , J. F. Silva2, L. Oliveira4  1 Institute of Polymers and Composites/I3N, Minho University, 4800-058 Guimaraes, Portugal 2 Department of Mechanical Engineering ISEP, 4200-072 Porto, Portugal 3 Department of Polymer Engineering, Minho University, 4800-058 Guimaraes, Portugal 4 PIEP - Pole for Innovation in Polymer Engineering, Minho University, 4800-058 Guimaraes, Portugal  (*)Email: jpn@dep.uminho.pt   ABSTRACT Two different types of natural fibers (jute and sisal) were studied and characterized, using optical microscopy, pycnometry density, single filament and linear density tests. Jute fibers were processed into composite parts from woven fabrics raw-material and sisal fibers were also processed into final composite components but in the form of chopped mat. Those fibers were used to reinforce polyester and epoxy matrices and therefore produce composite plates by resin infusion molding. Finally, the final obtained composite plates were submitted to mechanical testing, in order to assess their relevant mechanical properties.  INTRODUCTION During the past few decades, polymer matrix composites replaced, advantageously, many conventional materials, in various applications. This was possible because these materials have low density, excellent mechanical behavior and can be easily processed. The large majority of composite structures still use thermosetting matrices, like polyester or epoxy systems, even if, more recently, thermoplastic matrices are starting to be studied. (Mazumbar, 2012, Nunes, 2003). Recently, because of their interesting properties, natural fibers are being studied as reinforcement material in composite components. Usually they are low-costly, combine very low density with high specific properties, are biodegradable and nonabrasive, unlike other reinforcing fibers and also readily available (Saheb, 1999).  RAW MATERIALS AND COMPOSITE PROCESSING Jute and sisal fibers, chosen to be studied in this work, are between the most successfully used natural fibers as reinforcements in composite structures. The different natural fibers were impregnated and consolidated with two different thermoplastic resins: one orthophthalic polyester resin and one epoxy. Fibers were impregnated, at room temperature, by hand lay-up, with polyester and epoxy resins. Then, vacuum molding was employed to allow establishing a controlled consolidation pressure.  RESULTS Microscopy obtained images are depicted in figure 2. Fiber characterization results are summarized in tables 1 and 2. Guimarães/Portugal, 09-11 June 2013 Editor:  R. Fangueiro 2    a) Jute fiber (50×)                                     b)  Sisal fiber (100×)                                c)  Sisal fiber (100×) Fig. 2. Typical jute and sisal fiber geometries. Sisal fibers have two typical shapes, shown in pictures b) and c)              Table 1 Sisal single filament test results                         Table 2 Jute plain woven fabric specifications Gage length Deformation at break Tensile strength Tensile modulus (mm) (%) (MPa) (GPa) 20,00 3,22±0,28 760±114 28,1±0,97 25,00 2,81±0,70 763±9,2 19,4±0,66 30,00 2,64±0,42 461±185 14,7±0,13   Mass (g/m2) 204.0±7.0 Warp Linear density of the yarn (Tex) 140.5±9.5 Density (yarns/cm) 7.0±0.1 Crimp (%) 5.04±0.89 Weft Linear density of the yarn (Tex) 142.6±19.1 Density (yarns/cm) 6.6±0.5 Crimp (%) 2.44±1.24 Mechanical test results, for polyester matrix composites are summarized in table 3. Table 3 Mechanical test results of jute and sisal polyester matrix composites  Fiber type Strength (MPa) Elasticity modulus (GPa) Deformation at break (%) Tensile Jute 57,0±7,2 7,0±0,5 1,9±0,2 Sisal 24,8±3,9 5,4±0,3 1,5±0,3 Flexural Jute 91,5±3,8 5,9±0,2 2,8±0,1 Sisal 54,8±1,9 3,9±0,2 2,4±0,1  Acknowledgements The authors wish to thank the Engineering School ofthe University of Minho, PIEP – Pole for Innovation in Polymer Engineering and the School of Engineering of the Polytechnic of Porto, for the support given to this work. They also acknowledge the Portuguese Foundation for Science and Technology for the financial support of IPC through project PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25 - 2013-2014).   REFERENCES 1. Nunes, J. P., Silva, J. F., van Hattum, F.W. J., Bernardo, C. A., Marques, A. T., Brito, A. M. and Pouzada, A. S., “Production of thermoplastic towpregs and towpreg-based composites” in Polymer Composites – From Nano- to Macro-Scale, Eds K. Friedrich, S. Fakirov and Z. Zhang, Eds Kluwer Academic Publishers, 2005. 2. Sanjay Mazumdar “Growth opportunities: materials innovation will drive composites usage to new heights”. High Performance Composites, May 2012. 3. D. Nabi Saheb and J. P. Jog “Natural fiber polymer composites: A review” Advances in Polymer Technology, Vol. 18, No. 4, pp. 351–363 1999. 

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Development and assessment to environmentally friendly natural fiber composites

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