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Vol. 7. Num. 4.October - December 2018
Pages 403-616
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Vol. 7. Num. 4.October - December 2018
Pages 403-616
Original Article
DOI: 10.1016/j.jmrt.2018.03.008
Open Access
Charpy impact test of epoxy composites reinforced with untreated and mercerized mallow fibers
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Lucio Fabio Cassiano Nascimento
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lucio_coppe@yahoo.com.br

Corresponding author.
, Sergio Neves Monteiro, Luis Henrique Leme Louro, Fernanda Santos da Luz, Jheison Lopes dos Santos, Fábio de Oliveira Braga, Rubens Lincoln Santana Blazutti Marçal
Military Institute of Engineering – IME, Department of Materials Science, Praça General Tibúrcio 80, Praia Vermelha, Urca, 22290-270 Rio de Janeiro, RJ, Brazil
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Tables (6)
Table 1. Physical and mechanical properties of the mallow fibers.
Table 2. Types of specimens produced from the variation of the mercerization parameters.
Table 3. FTIR absorption bands for a natural fiber [32].
Table 4. Analysis of variance of the average impact energies obtained for the epoxy matrix composites reinforced with percentages from 0% to 30vol% of mallow fibers.
Table 5. Results for the differences between the mean values of Charpy impact energy in the volume fractions of mallow fiber 0 to 30% after application of the Tukey test.
Table 6. Comparison between tensile strength, young modulus and Charpy impact energy to composites reinforced with mallow fibers.
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Abstract

The mallow fiber (Urena lobata, linn) is demonstrating a great potential as reinforcement in polymer matrix composites. The difficulty in the use of the mallow, as in other natural lignocellulosic fibers (NLFs), is its hydrophilic compatibility with polymeric matrices that are typically hydrophobic. In order to improve the adhesion between the fiber surface and polymeric matrices, mallow fibers were subjected to mercerization treatment. In this work composites were produced with epoxy matrix reinforced with 30vol% of mallow fibers, both untreated and mercerized. By means of XRD analysis it was verified the variation of crystallinity in fibers treated with different NaOH solutions as well as immersion times and agitation. After this XRD preliminary analysis, a treatment of 5% NaOH solution for 24h without agitation was selected. The objective was to compare the Charpy impact energy of composites specimens produced with untreated mallow fibers and treated for the higher crystallinity obtained after the selected mercerization. For the analysis of impact energy the Tukey test was applied from which it could be assured, with a confidence level of 95%, that the epoxy specimens reinforced with 30vol% of untreated mallow fibers, had the best performance.

Keywords:
Mallow fibers
Epoxy composite
Mercerization
Charpy impact test
Full Text
1Introduction

Unlike synthetic fibers, natural lignocellulosic fibers (NLFs) do not have uniform properties. In fact, they are microstructurally heterogeneous and have dimensional limitation. The same type of NLF may considerably vary its properties depending on their origin, quality and age of the plant, as well as fiber diameter, aspect ratio and its preconditioning. This could significantly affect the performance of polymer composites reinforced with NLFs [1–12]. Another difference between NLFs and synthetic fibers is their interaction with water. Due to the presence of hydroxyl groups NLFs are hydrophilic, with high affinity with humidity. The fiber moisture content can vary between 5 and 10wt% [2,3].

The water on the surface of a NLF, reinforcing a composite, acts as a release agent at the interface of a hydrophobic polymer matrix. Further, due to evaporation of water, voids may appear in the matrix, resulting in loss of mechanical properties. One solution to reduce the moisture content and improve the interfacial adhesion is drying the NLF followed by pretreating the fibers by chemical modification of the surface [13–22].

Pretreatment enables the creation of increased roughness on the surfaces, which contributes to better adhesion to the polymer matrix. Among the different techniques for pretreating to produce NLFs surface modification, one of the most used is the alkaline treatment, also known as mercerization [17]. The mercerization removes both the waxes and greases as a portion of hemicellulose and lignin, enhancing the packing of the cellulose molecules and increasing crystallinity of the fibers. This results in a rougher surface with larger contact surface, aiding in mechanical anchoring and promoting an increase in both the elastic modulus and the tensile strength [23,24].

The mallow fiber (Urena lobata, linn) although widely used for making cordage in clothes as well as carpets, paper money, crafts among others [25], does not have so far a great use as reinforcing component in industrial composite products. However, physical and mechanical properties such as tensile strength have shown [26,27] a promising potential for using mallow fibers as reinforcement in polymer matrix composites (PMCs). Table 1 presents some of these properties.

Table 1.

Physical and mechanical properties of the mallow fibers.

Natural fiber  Diameter (μm)  Length (mm)  Specific mass (kg/m3Tensile strength (MPa)  Elongation at break (%)  Modulus of elasticity (GPa) 
Mallow  42.6  23.8  1374  160  5.2  17.4 

In this context, there is the possibility of using PMCs reinforced with mallow fibers in dynamic applications such as ballistic armor. Therefore, increased crystallinity of the mallow fibers and consequently the adhesion to the polymer matrix, through the mercerization treatment, may provide improvement in the mechanical properties of the composites. This could be the case of Charpy impact energy, which is investigated in the present work.

2Materials and methods

The mallow fibers were provided by the State University of North Fluminense (UENF) and acquired from the Textile Company Castanhal, Brazil Fig. 1 shows the as received mallow fibers. The polymer used as the material of the composite plate matrix was a commercial epoxy resin diglycidyl ether type of bisphenol A (DGEBA) cured with triethylene tetramine (TETA), using the phr of 13 parts of hardener to 100 parts of resin.

Fig. 1.
(0.16MB).

Mallow fibers as received by UENF.

Mallow fibers were added in two different situations as reinforcement in the manufacture of epoxy composite plates. In the first case the untreated fibers were cleaned, cut to a length of 150mm and dried in a stove for 24h. In the second case, mallow fibers were subjected to NaOH mercerizing treatment in the combination of parameters, according to Table 2.

Table 2.

Types of specimens produced from the variation of the mercerization parameters.

Concentration NaOH  Immersion time NaOH
  32448
5%  CP1  CP4  CP7 
10%  CP2  CP5  CP8 
20%  CP3  CP6  CP9 

The choice of immersion times was based on the effectiveness of the treatment. Indeed, a minimum of 3h was needed to reveal visible microstructural changes. By contrast, more than 48h treatment caused serious degradation to the fiber integrity. A 24h treatment time was selected as middle in between the extreme conditions.

After a preliminary selection based on the value of crystallinity obtained by X-ray diffraction (XRD), one specific treatment, the CP4 in Table 2 was applied. These treated mallow fibers were then incorporated into epoxy matrix for impact test. Charpy test specimens with untreated fibers were added into epoxy matrix in the volumetric fractions of 0%, 10%, 20% and 30%. Specimens with 5% NaOH for 24h treated fibers, relative to CP4 in Table 2, were added into the epoxy matrix in the volumetric fraction of 30%. Fig. 2 shows the various composite plates produced. These plates were cut in several Charpy specimens according to the standard [28].

Fig. 2.
(0.3MB).

Plates composite fiber percentage from 0 to 30vol% without treatment and 30vol% with treatment (mercerization – 5% NaOH).

The crystallinity index (Ic) of the cellulose was calculated by means of Eq. (1).

where I1 is the intensity of the minimum of diffraction, related to the amorphous part and I2 is the intensity of the maximum of diffraction, related to the crystalline part. This method was developed in 1959 by Segal et al. [29], and has been widely used for the study of natural fibers [30,31]. The XRD analyses were performed in a Shimadzu diffractometer, model XRD-6000, scan speed of 4°/min, power 30mA×40kV and scanning from 5° to 80°.

Fourier transform infrared (FTIR) analysis was conducted in a model IR Prestige 21-FTIR Shimadzu equipment. Samples of mallow fibers, both untreated and mercerized treated, were first milled followed by sieved for 20 mesh and then mixed with KBr. The mixture was then pressed to produce a film suitable for the analysis. Table 3 shows the FTIR absorption bands for a natural fiber [32].

Table 3.

FTIR absorption bands for a natural fiber [32].

Frequency (cm−1Assignment 
3200–3600  OH stretching 
2905  CH2 and CH3 stretching 
1740  Carbonyl (CO) Stretching of carboxylic acid or ester 
1650  HOH bending of absorbed water 
1616  Benzene ring stretching (lignin) 
1500  Benzene ring stretching (lignin) 
1440  CH2 bending in lignin 
1411  CH2 and CH3 bending 
1357  CH2 bending 
1320  CH2 wagging (lignin) 
1235  CO stretching of acetyl (lignin) 
1150  COC antisymmetric bridge stretching in cellulose and hemicellulose 
1110  OH association in cellulose and hemicellulose 
1028  CO stretching in cellulose, hemicellulose and lignin 
879  β-Glucosidic linkage 
600  Out of plant OH bending 

Dynamic mechanical analysis (DMA) test was carried out from 20 to 200°C in a model DMA Q800 TA Instrument using single cantilever 3 points bending specimens according to standard. A heating rate of 3°C/min and nitrogen atmosphere was applied for the test.

A total of 7 specimens for Charpy impact test were obtained by cutting each composite plates according to ASTM D6110 dimensions [28]. The tests were performed in a PANTEC instrumented pendulum, Model XC-50, 1×220V×60Hz. Fig. 3 illustrates the prepared specimens for the Charpy tests.

Fig. 3.
(0.17MB).

Specimens with mallow fiber for Charpy test. (a) 0vol%; (b) 10vol%; (c) 20vol%; (d) 30vol% without treatment and (e) 30vol% with treatment.

After impact tests, fragments of the ruptured specimens were collected and analyzed by scanning electron microscopy (SEM), in a model Quanta FEG FEI equipment.

3Results and discussion

Fig. 4 shows the FTIR spectra for: (a) untreated and (b) mercerized treated mallow fibers. These spectra reveal significant changes in the wavenumber interval from 800 to 1800cm−1. By comparing the values in Table 3 to the results of Fig. 4 one notice that the strong absorption band around 1050cm−1 for the untreated fiber, Fig. 4(a), which might correspond to the C – O stretching in cellulose, hemicellulose and lignin, has been considerably attenuated in the mercerized treated fiber, Fig. 4(b). Similarly, the absorption band around 1400cm−1 for the untreated, Fig. 4(a), which could be associated with CH2 bending or wagging in lignin, is practically inexistent in the treated fiber. One may then conclude that mercerization significantly affects the participation of lignin, which is a bonding substance for the cellulose, in the mallow fiber.

Fig. 4.
(0.16MB).

(a) FTIR to mallow fibers untreated; (b) FTIR to mallow fibers treated.

Fig. 5 shows DMA results for: (a) neat epoxy and (b) epoxy composites reinforced with 30vol % of mallow fibers. By comparing the two graphs, in general, it is observed an increase in onset of softening temperature of the storage modulus E′, as well as displacement to higher of the perks in the loss modulus “E”, and tangent delta. A possible interpretation for this behavior is an interference of the mallow fibers in the mobility of the epoxy chains, which postpones the occurrence of glass transition temperature.

Fig. 5.
(0.17MB).

(a) DMA to neat epoxy; (b) DMA to epoxy composites reinforced with 30vol% of mallow fibers.

The results obtained from the Charpy impact test for epoxy matrix composite reinforced with continuous and aligned mallow fibers, in percentages 0, 10, 20 and 30vol% without treatment as well as 30vol% with treatment, CP4 in Table 2, disclosed a good ability to absorb energy as compared to other polymer composites reinforced with NLFs [23]. Fig. 6 shows the results of Charpy absorbed energy (J/m) test for each group. It should be noticed that, as in other works [33,34], occurs an increase in average energy values with the fiber volume fraction used in the composite. High impact energy values can be related to low interfacial bonding, obtained by pullout tests, between the fibers and the matrix [35].

Fig. 6.
(0.25MB).

Results of Charpy impact test for the epoxy matrix composites reinforced with mallow fibers.

A low interfacial bonding between the mallow fiber and the epoxy matrix allows for easier decohesion during the impact, which causes fracture by delamination. This mechanism of fracture is more effective in composites with greater amount of reinforcement mallow fibers, above 10vol%.

In this case, it can increase the path to be followed by the crack, and therefore the absorbed energy required for fracture of the composite. Perhaps, because of this, there was a relative reduction of impact energy in the specimens produced with mercerized fibers as presented in Fig. 6. Due to the increased crystallinity of the fibers and consequently better adhesion to the epoxy matrix, cracks found difficult to propagate and create fractured surfaces that would be associated with higher impact energy.

Fig. 7 shows the diffractograms obtained for each mercerized sample, according to the various combinations of the parameters: concentration, immersion time and agitation. In this figure, 5% NaOH, 24h immersion and without agitation, CP4 was found in Fig. 7(a) to have a fiber crystallinity index (Ic) of 84.49%. This is higher than the value obtained for the other mercerization combinations and for the untreated mallow fibers (82.24%) in Fig. 7(b).

Fig. 7.
(0.19MB).

(a) Diffractogram for untreated mallow fibers; (b) diffractogram for mallow fibers mercerizing (CP4).

From the results obtained, the analysis of variance (Table 4) rejects the hypothesis that the means are equal to 5% significance level for the statistical “F”, on this account: F calculated >F critical (tabled). Therefore, the volume fraction of mallow fibers in epoxy matrix composites as well as the treatment of mercerizing has different effects on the Charpy impact energy.

Table 4.

Analysis of variance of the average impact energies obtained for the epoxy matrix composites reinforced with percentages from 0% to 30vol% of mallow fibers.

Variation causes  DF  Sun of squares  Mean square  F calc.  F crít (tab.) 
Treatments  3468899.11  867224.78  348.18  2.69 
Residue  30  74721.76  2490.73     
Total  34  3543620.88       

The Tukey test was applied for comparison, using a confidence level of 95%, to determine which volumetric fraction of mallow fibers provided better results in terms of Charpy impact energy. The less significant difference (LSD) obtained was 77.34. The results for the differences between the mean values of Charpy impact energy are shown in Table 5.

Table 5.

Results for the differences between the mean values of Charpy impact energy in the volume fractions of mallow fiber 0 to 30% after application of the Tukey test.

Volumetric fraction of mallow fibers  0%  10%  20%  30% without treatment  30% with treatment 
0%  46.59  470.63  809.41  65.36 
10%  46.59  424.04  762.83  18.77 
20%  470.63  424.04  338.78  405.27 
30% without treatment  809.41  762.83  338.78  744.05 
30% with treatment  65.36  18.77  405.27  744.05 

Based on these results, with 5% significance level, the reinforced composite with 30vol% mallow fibers without treatment showed better performance since it exhibited a higher average energy value of Charpy impact (905.49J/m). This is significantly distinct from the others because the differences are higher than LSD (77.34). Another important point to emphasize is the comparatively lower for the impact energy (161J/m) of 30vol % treated mallow fiber composite (CP4), Fig. 4, which is much lower than those of 20% and 30vol % and treated mallow fiber composite.

One possible explanation would be that the percentage of 10vol% in mallow fibers were not sufficient to produce an effective reinforcement in the epoxy matrix, which is associated with low results in Charpy impact energy. In all test specimens there was a similar complete rupture, making valid the results. In Fig. 8 it is shown the specimens ruptured after the Charpy test.

Fig. 8.
(0.33MB).

Specimens completely fractured after Charpy impact test. (a) 0vol%; (b) 10vol%; (c) 20vol%; (d) 30vol% without treatment and (e) 30vol% with treatment.

By visual analysis it can be seen a brittle fracture tendency in specimens with 0% and 10vol% untreated and 30vol% treated, which was confirmed by the impact energy values presented in Fig. 4. This figure shows a higher increase of more than 6 times in going from 10% to 20vol% mallow fibers. The SEM images in Figs. 9–11 show the way fracture mechanisms are involved in the impact process.

Fig. 9.
(0.56MB).

(a) Epoxy composite with 0vol% mallow fibers; (b) composite with 10vol% mallow fibers.

Fig. 10.
(0.36MB).

(a) Composite with 20vol% mallow fibers; (b) mallow fiber detail in composite with 20vol% of fibers.

Fig. 11.
(0.44MB).

(a) Epoxy composite reinforced with 30vol% untreated mallow fibers; (b) epoxy composite reinforced with 30vol% mallow fibers mercerized (5% NaOH, 24h and without agitation – CP4).

In Fig. 9(a) and (b) it is perceived clearly the brittle fracture mechanism by the presence of “river marks”, both in the specimen with 100% epoxy as well as the composite with 10vol% of fiber. These show that there was no effective reinforcement with low percentage of fibers.

For untreated composites with 20vol% of mallow fibers it was observed a greater amount of energy absorption owing to fracture mechanisms. Indeed, Fig. 10(a) revealed broken and detached fibers of the matrix, and a very effective encasement of the broken fibers by the epoxy matrix. On the contrary, the mercerized treated mallow fiber composite, evidence of delamination, i.e. separation between fiber and epoxy matrix, is observed in Fig. 10(b).

In the image of Fig. 11(a) for the untreated 30vol% mallow fiber composites one sees the fibers rupture, and the interfacial detachment from the epoxy matrix. These failure mechanisms led to the high absorption of impact energy as compared to the other percentages of untreated mallow fiber composites. However, the image of Fig. 11(b) for the mercerized-treated 30vol% shows the fracture surface like those of composites reinforced with untreated 0% and 10vol% fibers. Thus, the fracture was brittle and the absorbed energy was similar to that measured for reinforcement with 10vol% fiber.

Finally, Table 6 displays a comparison between the young modulus and tensile strength obtained in quasi-static, test velocity of 2mm/mm, and the impact energy. In this table one should notice that a relationship exists between the quasi-static mechanical properties and the absorbed impact energy. Indeed, the higher the amount of mallow fiber in the composite, the higher the stiffness, strength and impact energy. This emphasize the relevant effect of mallow fibers as reinforcement of epoxy composites.

Table 6.

Comparison between tensile strength, young modulus and Charpy impact energy to composites reinforced with mallow fibers.

Percentage of mallow fibers  Tensile strength (MPa)  Young modulus (GPa)  Charpy impact energy (J/m) 
0%  32.98±14.61  3.89±0.03  96.07±21.15 
10%  90.01±21.35  11.60±0.11  142.66±8.23 
20%  109.85±21.70  15.73±0.17  566.71±52.54 
30%  177.49±17.80  20.50±0.10  905.49±94.56 
4Conclusions

The Charpy impact energy increase with the volume fraction of mallow fibers incorporated into the epoxy matrix. Among the specimens evaluated by the Tukey test with 95% confidence level, the composite with 30vol% of mallow fibers without treatment was the one that exhibited the best results in terms of Charpy impact energy. This particular case indicates that natural fiber treatment is not beneficial to the composite performance.

Predominantly brittle fracture occurs in composites with volume fractions of 0% and 10vol% mallow fibers untreated as well as 30vol% mercerized fibers. These composites this play significantly lower Charpy impact energy than composite reinforced which untreated 20 and 30vol% of mallow fibers.

An index of crystallinity was obtained by XRD of 84.49% for CP4, which was treated with 5% NaOH, 24h immersion and without treatment. However, the improvement in crystallinity did not reflect as an increase in Charpy impact energy.

Composites with 20% and 30vol% mallow fibers without treatment provided a more effective reinforcing action. In these composites the fibers rupture was predominant mechanisms. This is evidenced by the average Charpy impact energy obtained, of the order 900J/m.

Conflicts of interest

The authors declare no conflicts of interest.

Acknowledgements

The authors thank the support to this investigation by the Brazilian agencies: CNPq, CAPES and FAPERJ; and UENF for supplying the mallow fibers.

References
[[1]]
A.K. Mohanty, M. Misra, G. Hinrichsen
Biofiber, biodegradable polymers and biocomposites: an overview
Macromol Mater Eng, (2000), pp. 1-24
[[2]]
A.K. Mohanty, M. Misra, L.T. Drzal
Sustainable bio-composites from renewable resources: opportunities and challenges in the green materials world
J Polym Environ, 10 (2002), pp. 19-26
[[3]]
A.N. Netravali, S. Chabba
Composites get greener
Mater Today, 6 (2003), pp. 22-29
[[4]]
J. Crocker
Natural materials innovative natural composites
Mater Technol, (2008), pp. 174-178
[[5]]
A.S. Singha, V.K. Thakur
Saccaharum cilliare fiber reinforced polymer composites
E-J Chem, 5 (2008), pp. 782-791
[[6]]
M.J. John, S. Thomas
Biofibers and biocomposites
Carbohydr Polym, 71 (2008), pp. 343-364
[[7]]
S.N. Monteiro, F.P.D. Lopes, A.S. Ferreira, D.C.O. Nascimento
Natural fiber polymer matrix composites: cheaper, tougher and environmentally friendly
JOM, 61 (2009), pp. 17-22
[[8]]
S.N. Monteiro, F.P.D. Lopes, A.P. Barbosa, A.B. Bevitori, I.L.A. Silva, L.L. Costa
Natural lignocellulosic fibers as engineering materials – an overview
Met Mater Trans A, 42 (2011), pp. 2963-2974
[[9]]
O. Faruk, A.K. Bledzki, H.P. Fink, M. Sain
Biocomposites reinforced with natural fibers
Progr Polym Sci, 37 (2012), pp. 1555-1596
[[10]]
V.K. Thakur, M.K. Thakur, R.K. Gupta
Review: Raw natural fibers based polymer composites
Intl J Polym Anal Charact, 19 (2014), pp. 256-271
[[11]]
A. Pappu, V. Patil, S. Jain, A. Mahindrakar, R. Haque, V.K. Thakur
Advances in industrial prospective cellulosic macromolecules enriched banana biofibre resources: a review
Int J Biol Macromol, 79 (2015), pp. 449-458 http://dx.doi.org/10.1016/j.ijbiomac.2015.05.013
[[12]]
O. Güven, S.N. Monteiro, E.A.B. Moura, J.W. Drelich
Re-emerging field of lignocellulosic fiber – polymer composites and ionizing radiation technology in their formulation
Polym Rev, 56 (2016), pp. 536-702
[[13]]
A.K. Bledzki, S. Reihmane, J. Gassan
Properties and modification methods for vegetable fibers for natural fiber composites
J Appl Polym Sci, 59 (1996), pp. 1329-1336
[[14]]
A.K. Bledzki, J. Gassan
Composites reinforced with cellulose based fibers
Progr Polym Sci, 4 (1999), pp. 221-274
[[15]]
X. Li, L.G. Tabil, S. Panigrahi
Chemical treatments of natural fiber for use in natural fiber – reinforced composites: a review
J Polym Environ, 15 (2007), pp. 23-25
[[16]]
A.S. Singha, V.K. Thakur, I.K. Mehta, A. Shama, A.J. Khanna, R.K. Rana
Surface-modified Hibiscus saddariffa fibers: physicochemical, thermal, and morphological properties evaluation
Int J Polym Anal Charact, 14 (2009), pp. 695-711
[[17]]
S. Kalia, B.S. Kaith, I. Kaur
Pretreatments of natural fibers and their application as reinforcing material in polymer composites – a review
Polym Eng Sci, 49 (2009), pp. 1253-1272
[[18]]
A.S. Singha, V.K. Thakur
Synthesis and characterizations of silane treated grewia optiva fibers
Int J Polym Anal Charact, 14 (2009), pp. 301-321
[[19]]
J. Summerscales, N. Dissanayake, A.S. Virk, W. Hall
A review of bast fibers and their composites. Part 1 – Fibers as reinforcement; Part 2 – Composites
Compos Part A, 41 (2010),
1329–35/1336–44
[[20]]
V.K. Thakur, A.S. Singha
Silane functionalization of saccaharum cilliare fibers: thermal, morphological, and physicochemical study
Int J Polym Anal Charact, 15 (2010), pp. 397-414
[[21]]
K.-Y. Lee, A. Delille, A. Bismarck
Greener surface treatments of natural fibers for the production of renewable composite materials
Cellulose fibers: bio- and nano-polymer composites, pp. 155-178
[[22]]
E. Zini, M. Scendola
Green composites – an overview
Polym Compos, 32 (2011), pp. 1905-1915
[[23]]
H. Ku, H. Wang, N. Pattarachayakoop, M. Trada
A review on tensile properties of natural fiber reinforced polymer composites
Compos Part B, 42 (2011), pp. 856-873
[[24]]
N. Thomas, S.A. Paul, L.A. Pothan, B. Deepa
Natural fibers: structure, properties and applications
Cellulose fibers: bio- and nano-polymer composites, pp. 3-42
[[25]]
Characteristics and applications of the mallow fiber. Available in http://www.ebah.com.br/content/ABAAAAyJAAG/fibra-malva [access 05.12.16].
[[26]]
Y.M. Moraes, C.G.Q. Ribeiro, F.M. Margem, S.N. Monteiro, J.I. Margem
Tensile strength tests in epoxy composites with high incorporation of mallow (malva) fibers. Characterization of minerals, metals and materials 2016
John Wiley & Sons, (2016)pp. 273-278
[[27]]
J.I. Margem, V. Gomes, R. Faria, F.M. Margem, M. Margem, S.N. Monteiro
Photoacoustic termal characterization of mallow (malva) fibers. Characterization of minerals, metals and materials 2015
John Wiley & Sons, (2015)pp. 259-264
[[28]]
American Society for Testing Materials D6110 – Standard Test Method for Determining the Charpy Impact Resistance of Notched Specimens of Plastics
ASTM, (2010)
[[29]]
L. Segal, J. Creely, A.E. Martin Jr., C.M. Conrad
An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer
Text Res J, 29 (1959), pp. 786-794
[[30]]
L.Y. Mwaikambo, M.P. Ansell
Chemical modification of hemp, sisal, jute and kapok fibers by alkalization
J Appl Polym Sci, 84 (2002), pp. 2222-2234
[[31]]
F.C. Ferreira, A.A.S. Curvelo, L.H.C. Mattoso
Chemical and structural characterization of sisal fibers from Agave sisalana variety
J Appl Polym Sci, 89 (2003), pp. 2957
[[32]]
A.K. Rana, R.K. Basak, B.C. Mitra, M. Lawther, A.N. Banerjee
Studies of acetylation of jute using simplified procedure and its characterization
J Appl Polym Sci, 64 (1997), pp. 1517-1523
[[33]]
D.U. Shah
Developing plant fibre composites for structural applications by optimizing composite parameters: a critical review
J Mater Sci, 48 (2013), pp. 6083-6107
[[34]]
O. Faruk, A.K. Bledzki, H.P. Fink, M. Sain
Progress report on natural fiber reinforced composites
Macromol Mater Eng, 299 (2014), pp. 9-26
[[35]]
C.Y. Yue, H.C. Looi, M.Y. Quek
Assessment of fiber-matrix adhesion and interfacial properties using the pull-out test
Int J Adhes Adhes, 15 (1995), pp. 73-80

Paper was part of technical contributions presented in the events part of the ABM Week 2017, October 2nd to 6th, 2017, São Paulo, SP, Brazil.

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Journal of Materials Research and Technology

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