Journal of Bionic Engineering 13 (2016) 426–435
Effect of Alkali and Silane Treatments on Mechanical and Fibre-matrix Bond Strength of Kenaf and Pineapple Leaf Fibres Mohammad Asim1, Mohammad Jawaid1, Khalina Abdan2, Mohamad Ridzwan Ishak3 1. Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, Serdang 43400, Malaysia 2. Department of Biological and Agricultural Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia 3. Department of Aerospace Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia
Abstract Natural fibres are very versatile materials, their properties vary with chemical composition and physical structure. The effects of alkali, silane and combined alkali and silane treatments on the mechanical (tensile), morphological, and structural properties of Pine Apple Leave Fibres (PALF) and Kenaf Fibres (KF) were investigated with the aim to improve their compatibility with polymer matrices. The effectiveness of the alkali and saline treatments in the removal of impurities from the fibre surfaces was confirmed by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared spectrometry (FTIR) observation. The morphological study of treated PALF and KF by SEM indicates that silane treated fibres have less impurities and lignin and hemicelluloses removed than those by other chemical treatments. Silane treated PALF and KF display better tensile strength than those of untreated, alkaline and NaOH-silane treated. Droplet test indicates that the Interfacial Stress Strength (IFSS) of alkali and silane treated PALF and KF are enhanced whereas silane treated fibres display highest IFSS. It is assumed that fibre treatments will help to develop high performance KF and PALF reinforced polymer composites for industrial applications. Keywords: pineapple leaves fibre, kenaf fibre, chemical treatment, tensile properties, structural properties, droplet test Copyright © 2016, Jilin University. Published by Elsevier Limited and Science Press. All rights reserved. doi: 10.1016/S1672-6529(16)60315-3
1 Introduction Natural fibres are the most important components of various industrial applications such as textile, paper making, packaging and building materials[1]. Since natural fibres are renewable and biodegradable materials, products made from such materials are also environmental friendly[2]. Natural fibres have many desirable advantages over synthetic fibres such as good acoustic property, thermal insulation[3], low density, low cost and high flexural strength[4]. These advantages are being utilized for various applications and highly recommended for building material applications[5]. Natural fibres are composed of cellulose, hemicellulose, lignin, pectins, waxes and water soluble substances[6]. However, the chemical composition and physical characteristics also defer with climatic conditions, age and retting process[7]. Corresponding author: Mohammad Jawaid E-mail:
[email protected]
Many fibre plants are available which have potentials to be use in industries as raw materials such as pineapple, kenaf, coir, abaca, sisal, cotton, jute, bamboo, banana, Palmyra, talipot, hemp, and flex. PALF are abundantly available waste materials of south-east Asian countries, used in producing fibres. PALF are constituted by cellulose (70% – 82%), lignin (5% – 12%), and ash (1.1%)[8]. PALF exhibit very good mechanical properties like tensile flexural and impact strength, which are highly desirable for making high quality of polymer composites. One drawback associated with PALF is the difficulty to make good interaction with hydrophobic polymers because it is hydrophilic in nature. Another example of natural fibres which can be an excellent substitute of synthetic fibres in south east Asian countries is Kenaf Fibre (KF)[9,10]. KF is very attractive option because of its fast growth, low cost, abundant availability and climatic tolerance[11]. The
Asim et al.: Effect of Alkali and Silane Treatments on Mechanical and Fibre-matrix Bond Strength of Kenaf and Pineapple Leaf Fibres
plastic and petroleum–based industries have huge demand of kenaf based materials[12]. Many treatments have been developed to improve interfacial bonding[13] and achieve better qualities in mechanical and water resistance properties. The most serious drawback of these natural fibres is their hydrophilic nature, which causes the weak interfacial bonding between fibre and matrix in polymer composites. Various physical impurities and the presence of hydroxyl groups on the fibre surface create difficulties to be used as enforcement materials[14]. Previously, several research works were carried out on treatments and modification of natural fibres to achieve desired qualities[15–17]. However, the mechanical performance of a composite material depends on the orientation and natures of fibres and matrix, the bonding between fibres and matrix also plays a very important role[18]. These weak bonding between fibres adversely affects the mechanical strength of fibre board[14]. Surface modification of natural hemp fibres using silane helped to minimize hydrophilic character[7]. In Ref. [19] PALF were treated with NaOH solution of various concentrations (1% w/v, 3% w/v, 5% w/v, and 7% w/v) and the treatment with 5% NaOH provided the best improvement of composite strength as compared with that of untreated fiber. In this paper, we studied the treatment of PALF with NaOH concentration 6% for 3h. In another work, KF were immersed in NaOH solution with different concentrations (3%, 6% and 9% NaOH) for 3h at room temperature and interesting to note that 6% NaOH yields the optimum concentration of NaOH for the chemical treatment[20]. Our study in a similar way, we considered optimum treatment, NaOH (6% for 3h) for KF and PALF, and comparing with silane (2% for 3h) and combination of alkali and silane treatments. In another study, surface of PALF was pre-treated with sodium hydroxide and modified with two different functionalities such as γ-aminopropyl trimethoxy silane and γ-methacryloxy propyl trimethoxy silane[21]. In this work, we used different procedure, chemical concentration and soaking time for PALF and KF. Alkali, silane and combine NaOH-silane treatments have been used on PALF and KF to modify the surface for good interfacial bonding with matrix. The aim of these treatments is to optimise chemical treatment of PALF and KF to fabricate high performance PALF/phenolic and KF/phenolic composites for aerospace components.
427
2 Experimental 2.1 Materials KF (Hibiscus cannabinus) was harvested from West Malaysian and retted while PALF (Ananas comosus) were harvested from Indonesia. The chemical used in this research are NaOH (Sodium Hydroxide 6% w/v soln, R&M) and Triethoxy(ethyl)silane (96%, Sigma Aldrich, Jasa Sejiwa Enterprise). For interfacial testing, phenolic resins modified powder (Grade- PH 3507) was used. 2.2 Chemical treatment PALF and KF were treated with three types of chemicals. The fibres were immersed into distilled water with different chemicals, combination of 2% silane and 6% NaOH, and combination of 6% NaOH and 2% silane (NaOH-silane) for 3h. After treatments, the fibres were thoroughly washed with running water several times until pH values were neutralized. Then, the fibres were dried in oven at 80 ˚C 48h. 3 Characterizations 3.1 Scanning Electron Microscopy (SEM) Morphological investigations were performed on the untreated and treated PALF and KF with SEM machine Model (HITACHI S-3400N). SEM instrument was used at an emission current of 58 μA and acceleration voltage of 5.0 kV, and the working distance was set to 6.2 mm. Before the SEM analysis, samples were coated with gold. SEM helps to do microscopic analysis and characterization of fibres on the basis of surface morphology and structural changes. 3.2 Diameter measurement Diameter test was performed on single fibre at room temperature. Accuracy of diameter measurement in natural fibre is very difficult to achieve because natural fibres are irregular in shape and thickness is not uniform[22]. Natural single fibre bundle consists of large amount of element fibres along with matrix of lignin and hemicelluloses. So, cross section of single fibre bundle is not circular. However, circular cross section was supposed in calculation of tensile properties, though cross section was irregular along to the length of fibre[23]. Untreated and treated single fibre bundle diameters were measured using an image analyser (Fig. 1). Five replicates of each sample were measured at four locations
428
Journal of Bionic Engineering (2016) Vol.13 No.3
along the length of fibre and the average diameter of each fibre was calculated. 3.3
standard test method for single fibre tensile test ASTM D 3379 with speed of 1 mm·min−1. Before testing, fibres were examined to remove those with cracks and partial breakages by image analyser. Tensile strength of fibres was calculated from following equation[20,24]
Fourier Transform Infrared Spectrometry (FTIR) FTIR study of both untreated and treated PALF and KF were carried out by using a FTIR machine (SHIMADZU81001, Japan) to investigate the changes in functional groups on the fibre surfaces. All spectra were recorded in the range from 4000 cm−1 to 500 cm−1.
where, T tensile strength in MPa, F force to maximum stress in N, A average fibre area in m2.
3.4 Tensile test PALF and KF treated with different chemicals as well as untreated fibres were compared by strength. Fig. 2 shows the sample preparation for testing. The fibres were attached and glued to the tab shape which was designed with the gauge length of 20 mm and tested by Universal Testing Machine (UTM), according to the
3.5 Droplet test To analyse the interfacial shear strength between fibre and matrix, micro-droplet bonding test was conducted. Single fibre was fixed with designed paper properly. Single drop of polymer was attached on the fibre and left for curing. The analysis was conducted using the following equation[25]
T = F/A
(1)
τ = F/(πDL) (2) where τ is the interfacial shear strength (MPa), D is the single fibre diameter (m), and L is the embedded length (m). Using a 5 kN INSTRON UTM, tests were conducted with a fixed cross-head displacement speed rate at 500 × 10−6 m·min−1. Six replicates for each sample (KF and PALF) of both treated and untreated fibres were tested. Moreover, the diameter of the fibre was measured from the nearest point of the droplet to the fibre contacts on both sides. Fig. 1 Measurement of fibre diameter.
4 Results and Discussion 4.1
Fig. 2 Tensile sample of single fibre test.
Fourier Transform Infrared Spectrometry (FTIR) FTIR spectra of untreated, NaOH, silane, and combined NaOH and silane treated PALF are illustrated in Fig. 3. For untreated PALF, the vibration peaks at 1200 cm−1 and 1500 cm−1 revealed the presence of lignin and hemicellulose structure, respectively[26].The peak at 1600 cm−1 revealed absorption of water[27]. The peak at 2900 cm−1 corresponds to the C-H stretching vibration from -CH2 group of cellulose and hemicelluloses. The broad band ranging from 3000 cm−1 to 3700 cm−1 were because of hydrogen bonded -OH vibration of the cellulosic structure. Table 1 shows the wave numbers and its functional groups[14,28]. NaOH treated PALF showed absence of vibration at peaks 1200 cm−1 and 1650 cm−1. This was accompanied
Asim et al.: Effect of Alkali and Silane Treatments on Mechanical and Fibre-matrix Bond Strength of Kenaf and Pineapple Leaf Fibres NaOH-silane
Control
120
Silane
NaOH
Transmittence(%)
100 80 60 40 20 0
0
500 1000 1500 2000 2500 3000 3500 4000 4500 Wave number (cm−1)
Fig. 3 FTIR spectra of untreated, NaOH, silane and NaOH-silane treated PALF. Table 1 The wave numbers of peaks used for FTIR analysis and corresponding functional groups and vibrational type[9,22] Wavenumber
Functional group
Vibrational type
3500–3700
O-H
O-H stretching
2912
-CH2-
C-H stretching
1715
R(CaO)OH
CaO stretching
1474
-CH2-
C-H bending, crystalline
1464
-CH2-
C-H bending, amorphous
908
RCHaCH2
C-CH2 out of plane bending
1000–650
=C-H
alkenes
Control
120
NaOH
NaoH-silane
Saline
Transmittence(%)
100 80 60 40 20 0
0
500 1000 1500 2000 2500 3000 3500 4000 4500
Fig. 4 FTIR spectra of untreated, NaOH, silane and NaOH-silane treated KF.
by a reduction in peak intensity at 1436 cm−1. NaOH treatment was the cause of partial leaching out of lignin and complete decomposition of hemicellulose. Alkali treatment was prone to attack the hemicellulose in sisal and jute rather than lignin[29]. These vibrations revealed that the hemicellulosic ester was more easily removed by an alkali solution. Silane treated PALF showed similar graph as NaOH graph revealed its effect on lignin and hemicelluloses. The vibration peak present at 847 cm−1 duo to Si-C stretching bond revealed silane presence on the PALF surface [16]. This was an indication of very good interfacial interaction between the silane coupling agent and the surface of the PALF[30]. The vi-
429
bration peaks at 1300 cm−1 and 1675 cm−1 indicated N-H and C-H bonding respectively, stretching vibration of carboxylic acid or ester invisible in the spectrum of NaOH-silane treated PALF[19]. Chemical modification of KF were analysed by FTIR, untreated, NaOH, silane, and combined NaOH and silane treated KF are compared in Fig. 4. Untreated KF revealed the typical broad peak of cellulosic fibres from 1200 cm−1 to 1500 cm−1 of lignin and hemicelluloses structure. The vibration peak at 1685 cm−1 revealed ester carbonyl group[31]. Another peak at 2900 cm−1 mostly arose from C-H stretching[32,33], whereas the vibration peak at 3400 cm−1 indicated O-H frequency. In treated KF with NaOH and NaOH-silane revealed low intensity peak from 1200 cm−1 to 1500 cm−1, while silane treated KF was more or less same as untreated KF. These vibrations indicated that huge amount of the lignin were remove[34]. For NaOH and NaOH-silane treated KF, another peak was shifted to 1635 cm−1.this peak revealed the carbonyl group of the acetyl ester in hemicellulose and the carbonyl aldehyde in lignin[35]. Both treated KF with NaOH and silane removed hemicellulose, wax content and lignin effectively. NaOH removed some cellulosic materials also, which may affect strength of fibres. These chemical treatments helped to reduce water absorption of both fibres. In KF, NaOH-silane treatment did not affect the chemical composition in good proportion. While in PALF, NaOH-silane removed lignin, hemicellulose and wax content equivalent to NaOH treated fibres. It is assumed that absence of lignin, hemicellulose and wax containing chemicals on the fibre surface enhances the compatibility between fibre and polymer matrix, and it will not affect the mechanical strength of fibres. 4.2 Scanning Electron Microscopy (SEM) SEM analysis was used to study the surface morphology of PALF and KF. The morphology of KF before and after chemical treatments was compared. Fibre surface plays very important role in interfacial bonding between fibres and resin resulting in better mechanical properties[15]. The microscopic analysis of fibre surface morphology is of utmost importance in characterizing the structural changes that occurred upon treatment which helps in cleansing and smoothening of fibres. Fig. 5 shows untreated and treated surfaces of KF. Fig. 5a
Journal of Bionic Engineering (2016) Vol.13 No.3
430 (a)
(b)
10.0 µm (c)
10.0 µm (d)
10.0 µm
10.0 µm
Fig. 5 SEM of (a) untreated, (b) NaOH, (c) silane and (d) NaOH-silane treated KF. (a)
(b)
10.0 µm
10.0 µm (c)
(d)
10.0 µm
10.0 µm
Fig. 6 SEM of (a) untreated, (b) NaOH, (c) silane and (d) NaOH-silane treated of PALF.
shows the SEM micrograph of untreated KF. There are many impure materials on the surface of untreated fibres. Treated KF with NaOH in Fig. 5b shows very clean and smooth surface. It shows very good effect of 6% concentration NaOH on KF. Edeerozey et al[20] reported that KF treated with NaOH with 6% concentration removed all impurities from surfaces of fibres. Silane treated fibre in Fig. 5c shows clean and removed impurities from surface. Silane treatment is very helpful for removal of lignin and hemicelluloses from natural fibres [16]. Due to
silane removal of hemicellulose and lignin helped to enhance kenaf fibre-matrix interfacial bonding[11]. Fig. 5d shows that NaOH-silane treatment of KF has no obvious effect in comparison with other treatments. Fig. 6 illustrates untreated and treated surfaces of PALF. Untreated PALF showed impurities on fibre surface in Fig. 6a. Fig. 6b shows the fibre treated with NaOH, which improved surface quality and made the fibre surface very smooth. The smooth surface suggests no foreign material and the small pores on the surface
Asim et al.: Effect of Alkali and Silane Treatments on Mechanical and Fibre-matrix Bond Strength of Kenaf and Pineapple Leaf Fibres
431
Table 2 Diameter, tensile strength, tensile modulus and IFSS of PALF and KF Testing Fibre diameter (µm) Tensile strength (MPa) Tensile modulus (MPa) IFSS (MPa)
Fibres
Untreated
NaOH-silane
NaOH
Silane
PALF
78.8
50.6
47.8
42.4
KF
83.5
52
46.4
39.4
PALF
290.61
424.63
432.01
629.90
KF
282.60
247.81
455.74
551.23
PALF
5381.59
6599.71
8396.76
10998.39
KF
7132.65
11867.02
15247.35
19707.86
PALF
1.70
1.93
1.81
2.35
KF
1.27
1.71
2.89
4.54
100 PALF KF
90 80 70 60 50 40 30 20 10 0
Untreated NaOH(6%)-silane(2%) NaOH(6%) Silane(2%)
The treatment with 2% silane was most effective treatment among all the treatments, while 6% NaOH treatment also revealed better impact on both fibres. The diameters of all treated fibres decrease, the influences of different treatments on fibre diameters are slightly difference as shown in Table 2. Higher concentrations of NaOH and longer soaking time could weaken fibres and make them more brittle[38]. The results of this study clearly shows that treated fibre with 2% silane was able to break the lignin and hemicellulose web of fibre bundle and maintained its mechanical properties, see in Table 2.
Fig. 7 Diameter of PALF and KF.
indicate the absence of lignin and hemicellulose. The pores can lead to better interfacial bonding[36]. PALF treated with silane in Fig. 6c shows improvements with lots of voids. These voids help to make strong interfacial bonding. Fibres treated with NaOH-silane in Fig. 6d shows very less improvement in morphology, which lead to poor bonding between fibres and matrix[20]. Puglia et al.[16] reported that NaOH treated fibres can remove surface impurities while silane treated fibres are smoother, resulting in good bonding with matrix. 4.3 Diameter measurement Effects of chemical treatments separated fibres into small fraction and these fibres revealed with increased surface area and rougher structure to help better interfacial bonding[37]. Diameters of untreated and treated PALF and KF are given in Table 2. In Fig. 7, it clearly shown that untreated fibres were larger in diameter than treated fibres. These chemicals attacked on both fibre surfaces and broke the web of lignin and hemicellulose and then separated fibres from the bundles[22]. In this study, diameters of chemical treated fibres were more uniform and smaller than untreated fibres.
4.4 Tensile strength The variation of tensile strength of untreated and treated PALF and KF are shown in Fig. 8. Chemical treatments of fibres enhanced the tensile strength of fibres[20]. Alkali treatment was also very effective in removal of impurities[39], and the removal of impure materials depends on the concentration of NaOH and soaking time, that can affect the tensile strength[38]. It was also shown that tensile strength of silane treated and NaOH treated fibres improved over that of untreated fibres. Chemical treatments of fibres enhanced the tensile properties of fibres by removing lignin and hemicelluloses and got cemented with the cellulose[40]. Fig. 8 shows the effects of chemical treatments on the tensile strength of PALF and KF. Both fibres treated with 2% concentration of silane showed highest tensile strengths. Untreated PALF and KF showed tensile strength 290.6 MPa and 282.6 MPa, respectively. PALF treated with NaOH-silane had lowest tensile strength among all treated fibres, while the tensile strength of KF treated with NaOH-silane was even lower than that of untreated fibres. PALF fibres treated with NaOH 6% concentration showed the similar strength to the PALF fibres treated with NaOH-silane, while for NaOH treated
Journal of Bionic Engineering (2016) Vol.13 No.3
432 700
Tensile strength (MPa)
600
PALF KF
500 400 300 200 100 0
Untreated NaOH(6%)-silane(2%) NaOH(6%)
Silane(2%)
Tensile modulus (MPa)
Fig. 8 Tensile strength of PALF and KF.
Fig. 9 Tensile modulus of PALF and KF.
KF, the tensile strength was about two times of that treated with NaOH-silane. Fibres treatment with 6% of NaOH was very effective to remove surface impurities of PALF[41]. But silane treated fibre showed better interfacial bonding between matrix and fibres because it removed lignin and hemicellulose[15]. Higher chemical concentration may remove impurity efficiently but may decrease tensile strength due to lignocellulose degradation and rupture of fibre surfaces[42]. Effect of silane treatment was much higher than other treatments. In case of PALF, only silane treatment is significant while other treatments show very similar trend of no-treatment. 4.5 Tensile modulus Tensile modulus measurement is for the calculation of rigidity of material. The chemical treatments resulted
in the increase in tensile moduli of both PALF and KF as shown in Fig. 9. The variations in the tensile moduli of untreated and treated fibres were similar to the tensile strengths. Tensile moduli of thet two treated fibres with NaOH-silane were higher than the untreated fibres. The maximum tensile moduli occurred when the fibres were treated with a solution of silane at 2% concentration. All tensile moduli are shown in Table 2. For the treated PALF with silane the tensile modulus increased by 105% compared to the untreated PALF, while same treatment of KF the tensile modulus increased by 175% compared to untreated KF. Both PALF and KF treated with NaOH at 6% concentration also showed higher tensile moduli than untreated PALF and KF. However, NaOH treated PALF showed 50% lesser and KF showed 60 % less than PALF and KF treated with silane respectively. Low tensile moduli of NaOH treated fibres can caused fibre damage due to excess of delignification[43]. Highest tensile modulus of silane treated fibre ensured that impurity of fibre surface was fully removed, which was also seen in SEM. Maximum tensile strength and modulus were highest in silane only, while NaOH-silane treated fibre revealed very low tensile modulus. The tensile modulus of NaOH-silane fibre dropped significantly due to higher solution concentration[16]. 4.6 Droplet test Interfacial shear strength test (droplet test) find out interfacial properties of the fibres reinforced polymer composites. Interfacial bond between fibres and matrix are shown in Fig.10. Droplet test results clearly showed that the highest IFSS was obtained from the silane treated fibres. Fig. 10a clearly showed the fibre with small drop of matrix. Fig. 10b showed the same fibre after test and clearly identified the break of matrix. The IFSS values of untreated PALF and KF were 1.70 MPa and 1.27 MPa, respectively (Table 2). Silane treatment showed highest improvement in fibre- matrix bonding of PALF and KF shown in Fig. 11. Silane treated PALF has near about 40% higher IFSS than untreated PALF fibres, while KF showed IFSS near about 400% higher than untreated KF. NaOH treated PALF showed very less improvement of 7% strength enhancement, while KF showed better improvement with 130%. According to Nirmal et al[44], alkali treated fibre increased IFSS of fibre and polymer by 115%. In comparison to other
Asim et al.: Effect of Alkali and Silane Treatments on Mechanical and Fibre-matrix Bond Strength of Kenaf and Pineapple Leaf Fibres
433
hemp fibre reinforced polylactide and unsaturated polyester composites[25].
5 Conclusion
Fig. 10 Droplet test. (a)Before test; (b) after test. 6 PALF KF
5
The effects of NaOH, silane and NaOH-silane treatments on the morphological, structural and tensile properties of PALF and KF were investigated in this work. It was identified from SEM graphs that non cellulosic materials were removed from silane treated PALF and KF. FTIR spectra show that silane treated PALF and KF reduces their hydrophilic characteristics. In comparison of diameter of both untreated PALF and KF, silane treated fibres display reduction in its diameter due to removal of impurities. Tensile properties of silane treated PALF and KF are enhanced as compared with the untreated, alkali treated and NaOH-silane treated fibres. Silane treated PALF and KF have the highest IFSS. The results obtained in this study may help the fabrication of PALF and KF reinforced composites using silane treated PALF and KF.
Acknowledgment IFSS (MPa)
4
The authors are thankful to the Ministry of Science and Technology (MOSTI), E-Science Vote (No. 5450760) for supporting this research work.
3
2
References
1
[1]
Ashori A. Nonwood fibers—A potential source of raw material in papermaking. Polymer-Plastics Technology and
0
Control
NaOH(6%)
Silane(2%) NaOH(6%)-silane(2%)
Engineering, 2006, 45, 1133–1136. [2]
Fig. 11 IFSS test of PALF and KF.
treated fibre, improvement in PALF was very less while improvement in KF was significant. Fibres treated with NaOH-silane, the IFSS of PALF was enhanced only by 11.35% and that of KF was enhanced only by 13.47%. NaOH treatmed and NaOH-silane treated fibres are not as effective as the silane treated in improving the IFSS of PALF and KF. The highest IFSS improvement was observed in silane treated fibres. This result was probably due to the effects of the elimination of lignin and hemicellulose. Removal of these compounds led to voids in the fibres, which helped to make an anchor between matrix and fibres, the coupling agent penetrated the fibres and deposited in the interfibrillar regions, The effect of fibre treatments on interfacial shear strength of
Saba N, Tahir P M, Jawaid M. A review on potentiality of nano filler/natural fiber filled polymer hybrid composites. Polymers, 2014, 6, 2247–2273.
[3]
Thakur V K, Singha A S, Mehta I K. Renewable resource-based green polymer composites: Analysis and characterization. International Journal of Polymer Analysis and Characterization, 2010, 15, 137–146.
[4]
Petchwattana N, Covavisaruch S. Mechanical and morphological properties of wood plastic biocomposites prepared from toughened poly (lactic acid) and rubber wood sawdust (Hevea brasiliensis). Journal of Bionic Engineering, 2014, 11, 630–637.
[5]
Sedan D, Pagnoux C, Smith A, Chotard T. Mechanical properties of hemp fibre reinforced cement: Influence of the fibre/matrix interaction. Journal of the European Ceramic Society, 2008, 28, 183–192.
[6]
Li X, Tabil L G, Panigrahi S. Chemical treatments of natural
434
Journal of Bionic Engineering (2016) Vol.13 No.3
fiber for use in natural fiber-reinforced composites: A review. [7]
[19] Lopattananon N, Panawarangkul K, Sahakaro K, Ellis B.
Rachini A, Le Troedec M, Peyratout C, Smith A. Chemical
Performance of pineapple leaf fiber–natural rubber com-
modification of hemp fibers by silane coupling agents.
posites: The effect of fiber surface treatments. Journal of
Journal of Applied Polymer Science, 2012, 123, 601–610. [8]
Asim M, Abdan K, Jawaid M, Nasir M, Dashtizadeh Z,
Applied Polymer Science, 2006, 102, 1974–1984. [20] Edeerozey A M, Akil H M, Azhar A, Ariffin M Z. Chemical
Ishak M R, Hoque M E. A review on pineapple leaves fibre
modification of kenaf fibers. Materials Letters, 2007, 61,
and its composites. International Journal of Polymer Sci-
2023–2025.
ence, 2015, 2015, 950567. [9]
Advanced Composite Materials, 2013, 22, 109–121.
Journal of Polymers and the Environment, 2007, 15, 25–33.
[21] Threepopnatkul P, Kaerkitcha N, Athipongarporn N. Effect
Aji I, Sapuan S, Zainudin E, Abdan K. Kenaf fibres as re-
of surface treatment on performance of pineapple leaf
inforcement for polymeric composites: A review. Interna-
fiber–polycarbonate composites. Composites Part B: Engi-
tional Journal of Mechanical and Materials Engineering,
neering, 2009, 40, 628–632.
2009, 4, 239–248.
[22] Kabir M, Wang H, Lau K, Cardona F. Tensile properties of
[10] Khalil H P S A, Yusra A F I, Bhat A H, Jawaid M. Cell wall
chemically treated hemp fibres as reinforcement for com-
ultrastructure, anatomy, lignin distribution, and chemical
posites. Composites Part B: Engineering, 2013, 53,
composition of Malaysian cultivated kenaf fiber. Industrial
362–368.
Crops and Products, 2010, 31, 113–121. [11] Asumani O M L, Reid R G, Paskaramoorthy R. The effects of alkali–silane treatment on the tensile and flexural prop-
[23] Mukhopadhyay S, Fangueiro R, Arpac Y, Şentürk Ü. Banana fibers–variability and fracture behaviour. Cellulose, 2008, 31, 39–45.
erties of short fibre non-woven kenaf reinforced polypro-
[24] Ishak M R, Sapuan S M, Leman Z, Rahman M Z A, Anwar
pylene composites. Composites Part A: Applied Science and
U M K. Characterization of sugar palm (Arenga pinnata)
Manufacturing, 2012, 43, 1431–1440.
fibres. Journal of Thermal Analysis and Calorimetry, 2011,
[12] Bernard M, Khalina A, Ali A, Janius R, Faizal M, Hasnah K,
109, 981–989.
Sanuddin A. The effect of processing parameters on the
[25] Sawpan M A, Pickering K L, Fernyhough A. Effect of fibre
mechanical properties of kenaf fibre plastic composite.
treatments on interfacial shear strength of hemp fibre rein-
Materials & Design, 2011, 32, 1039–1043.
forced polylactide and unsaturated polyester composites.
[13] Essabir H, Achaby M E, Hilali E M, Bouhfid R, Qaiss A. Morphological, structural, thermal and tensile properties of
Composites Part A: Applied Science and Manufacturing, 2011, 42, 1189–1196.
high density polyethylene composites reinforced with
[26] Ray D, Sarkar B. Characterization of alkali-treated jute
treated Argan nut shell particles. Journal of Bionic Engi-
fibers for physical and mechanical properties. Journal of
neering, 2015, 12, 129–141.
Applied Polymer Science, 2001, 80, 1013–1020.
[14] Terpakova E, Kidalova L, Eštoková A, Čigášová J, Števu-
[27] Samal R, Ray M C. Effect of chemical modifications on
lová N. Chemical modification of hemp shives and their
FTIR spectra. II. Physicochemical behavior of pineapple
characterization. Procedia Engineering, 2012, 42, 931–941.
leaf fiber (PALF). Journal of Applied Polymer Science, 1997,
[15] Meon M S, Othman M F, Husain H, Remeli M F, Syawal M
64, 2119–2125.
S M. Improving tensile properties of kenaf fibers treated
[28] Stark N M, Matuana L M. Surface chemistry changes of
with sodium hydroxide. Procedia Engineering, 2012, 41,
weathered HDPE/wood-flour composites studied by XPS
1587–1592.
and FTIR spectroscopy. Polymer Degradation and Stability,
[16] Puglia D, Monti M, Santulli C, Sarasini F, De Rosa I M,
2004, 86, 1–9.
Kenny J M. Effect of alkali and silane treatments on me-
[29] Mwaikambo L Y, Ansell M P. Chemical modification of
chanical and thermal behavior of Phormium tenax fibers.
hemp, sisal, jute, and kapok fibers by alkalization. Journal of
Fibers and Polymers, 2013, 14, 423–427.
Applied Polymer Science, 2002, 84, 2222–2234.
[17] Sgriccia N, Hawley M C, Misra M. Characterization of
[30] Huda M S, Drzal L T, Mohanty A K, Misra M. Effect of
natural fiber surfaces and natural fiber composites. Com-
chemical modifications of the pineapple leaf fiber surfaces
posites Part A: Applied Science and Manufacturing, 2008,
on the interfacial and mechanical properties of laminated
39, 1632–1637.
biocomposites. Composite Interfaces, 2008, 15, 169–191.
[18] Huo S, Thapa A, Ulven C. Effect of surface treatments on
[31] Razak N I, Ibrahim N A, Zainuddin N, Rayung M, Saad W Z.
interfacial properties of flax fiber-reinforced composites.
The influence of chemical surface modification of kenaf
Asim et al.: Effect of Alkali and Silane Treatments on Mechanical and Fibre-matrix Bond Strength of Kenaf and Pineapple Leaf Fibres
435
fiber using hydrogen peroxide on the mechanical properties
[38] Hossain M K, Dewan M W, Hosur M, Jeelani S. Mechanical
of biodegradable kenaf fiber/poly(lactic acid) composites.
performances of surface modified jute fiber reinforced bio-
Molecules, 2014, 19, 2957–68.
pol nanophased green composites. Composites Part B: En-
[32] Joonobi M, Harun J, Tahir P M, Zaini L H, SaifulAzry S, Makinejad M D. Characteristic of nanofibers extracted from kenaf core. BioResources, 2010, 5, 2556–2566. [33] El Mechtali F Z, Essabir H, Nekhlaoui S, Ouadi Bensalah M,
gineering, 2011, 42, 1701–1707. [39] Das M, Chakrabarty D. Thermogravimetric analysis and weathering study by water immersion of alkali treated bamboo fibres. BioResources, 2008, 3, 1051–1062.
Jawaid M, Bouhfid R, Qaiss A. Mechanical and thermal
[40] Guimarães J L, Frollini E, Da Silva C G, Wypych F, Sat-
properties of polypropylene reinforced with almond shells
yanarayana K. Characterization of banana, sugarcane ba-
particle: Impact of chemical treatments. Journal of Bionic
gasse and sponge gourd fibers of Brazil. Industrial Crops
Engineering, 2015, 12, 483–494.
and Products, 2009, 30, 407–415.
[34] Sun R, Sun X, Fowler P Tomkinson J. Structural and
[41] Sreekala M, Kumaran M, Thomas S. Oil palm fibers: Mor-
physico-chemical characterization of lignins solubilized
phology, chemical composition, surface modification, and
during alkaline peroxide treatment of barley straw. European
mechanical properties. Journal of Applied Polymer Science,
Polymer Journal, 2002, 38, 1399–1407.
1997, 66, 821–835.
[35] Hamdan S, Talib Z A, Rahman M R. Dynamic Young’s
[42] Ibrahim N A, Hadithon K A, Abdan K. Effect of fiber
modulus measurement of treated and post-treated tropical
treatment on mechanical properties of kenaf fiber-ecoflex
wood polymer composites (WPC). BioResources, 2009, 5,
composites. Journal of Reinforced Plastics and Composites,
324–342.
2010, 29, 2192–2198.
[36] Aziz S H, Ansell M P. The effect of alkalization and fibre
[43] Mishra S, Mohanty A, Drzal L, Misra M, Parija S, Nayak S,
alignment on the mechanical and thermal properties of kenaf
Tripathy S. Studies on mechanical performance of
and hemp bast fibre composites: Part 1–polyester resin ma-
biofibre/glass reinforced polyester hybrid composites.
trix. Composites Science and Technology, 2004, 64,
Composites Science and Technology, 2003, 63, 1377–1385.
1219–1230.
[44] Nirmal U, Singh N, Hashim J, Lau S T, Jamil N. On the
[37] Goud G, Rao R. Effect of fibre content and alkali treatment
effect of different polymer matrix and fibre treatment on
on mechanical properties of Roystonea regia-reinforced
single fibre pullout test using betelnut fibres. Materials &
epoxy partially biodegradable composites. Bulletin of Ma-
Design, 2011, 32, 2717–2726.
terials Science, 2011, 34, 1575–1581.