This article was downloaded by: [University of Sussex Library] On: 16 August 2014, At: 16:54 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Journal of Adhesion Science and Technology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tast20 The effect of the Thymus vulgaris extracts on the physicochemical characteristics of cedar wood using angle contact measurement Moulay Sadiki a , Hassan Barkai a , Saad Ibnsouda Koraichi ab & Soumya Elabed ab a Laboratory of Microbial Biotechnology, Faculty of Science and Technology, BP 2202, 30007 Fez, Morocco b Regional University Center of Interface, University Sidi Mohamed Ben Abdellah, BP 2626, 30007 Fez, Morocco Published online: 17 Jul 2014. To cite this article: Moulay Sadiki, Hassan Barkai, Saad Ibnsouda Koraichi & Soumya Elabed (2014): The effect of the Thymus vulgaris extracts on the physicochemical characteristics of cedar wood using angle contact measurement, Journal of Adhesion Science and Technology To link to this article: http://dx.doi.org/10.1080/01694243.2014.929197 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
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This article was downloaded by: [University of Sussex Library]On: 16 August 2014, At: 16:54Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Adhesion Science andTechnologyPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/tast20
The effect of the Thymus vulgarisextracts on the physicochemicalcharacteristics of cedar wood usingangle contact measurementMoulay Sadikia, Hassan Barkaia, Saad Ibnsouda Koraichiab &Soumya Elabedab
a Laboratory of Microbial Biotechnology, Faculty of Science andTechnology, BP 2202, 30007 Fez, Moroccob Regional University Center of Interface, University Sidi MohamedBen Abdellah, BP 2626, 30007 Fez, MoroccoPublished online: 17 Jul 2014.
To cite this article: Moulay Sadiki, Hassan Barkai, Saad Ibnsouda Koraichi & Soumya Elabed (2014):The effect of the Thymus vulgaris extracts on the physicochemical characteristics of cedar woodusing angle contact measurement, Journal of Adhesion Science and Technology
To link to this article: http://dx.doi.org/10.1080/01694243.2014.929197
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the“Content”) contained in the publications on our platform. However, Taylor & Francis,our agents, and our licensors make no representations or warranties whatsoever as tothe accuracy, completeness, or suitability for any purpose of the Content. Any opinionsand views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Contentshould not be relied upon and should be independently verified with primary sourcesof information. Taylor and Francis shall not be liable for any losses, actions, claims,proceedings, demands, costs, expenses, damages, and other liabilities whatsoever orhowsoever caused arising directly or indirectly in connection with, in relation to or arisingout of the use of the Content.
This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
The effect of the Thymus vulgaris extracts on the physicochemicalcharacteristics of cedar wood using angle contact measurement
Moulay Sadikia, Hassan Barkaia, Saad Ibnsouda Koraichia,b and Soumya Elabeda,b*
aLaboratory of Microbial Biotechnology, Faculty of Science and Technology, BP 2202, 30007,Fez, Morocco; bRegional University Center of Interface, University Sidi Mohamed Ben Abdellah,
BP 2626, 30007, Fez, Morocco
(Received 8 December 2013; final version received 25 May 2014; accepted 26 May 2014)
The aim of the study was to investigate the effect of crude extracts of Thymus vul-garis on wood surface physicochemical characteristics. Thus, the Lifshitz-van derWaals (cLW), acid–base (surface tension components ΔGiwi, electron donor (c�) andelectron acceptor (cþ) parameters of untreated and treated wood were assessed usingcontact angle measurement. The main results showed that all T. vulgaris extracts areable to change wood surface properties. Indeed, the samples treated with the productobtained by maceration and ultrasound indicated the hydrophilic character(θw = 29.7 ± 0.3°, ΔGiwi = 17. 78 ± 0.48 mJ/m2 and θw = 18.2 ± 0.2°, ΔGiwi = 30.62± 0.31 mJ/m2) respectively, and had less contact angle values than that of untreatedwood (θw = 86.0 ± 0.2°). In addition, this treatment has made the wood more donor(c� = 44.76 ± 0.3 mJ/m2 and c� = 53.80 ± 0.3 mJ/m2) than the electron acceptor com-pared to sample control (cþ = 2.03 ± 0.04 mJ/m2). Finally, the effect of the extractobtained by ultrasound was found to be more important and significant than thoserecovered by classical extraction.
Keywords: physicochemical characteristics; wood; T. vulgaris; contact angle;ultrasound; wood surface
Introduction
Wood is a lignocellulosic material that has broad uses in architecture, building anddiverse industrial sectors. Cedar wood, in particular, was widely employed in variousforms of construction and decoration in such majestic edifices as mausoleums, magnifi-cent palaces and riads.[1]
Despite its many qualities, cedar is a complex biomaterial, rich and sensitive to dif-ferent agents of degradation, including microorganisms causing huge economic lossesby adhering to the surface and forming biofilms.[2] The adhesion point is a key andimportant step in the process of biofilm formation and is governed by different interac-tions between microorganisms and substrate, which are van der Waals, electrostatic andacid–base interference. These latter depend on the physicochemical characteristic of thematerial and the microbial surface, especially its wettability (hydrophobicity and hydro-philicity), surface tension, and electron donor–acceptor properties.[3–5]
There is great interest in relating the physicochemical properties of surface materialsto the responses that they generate upon contact with various liquids used in differentfields. Indeed, they can be incorporated into methods for prediction of interaction
between liquid, microorganisms and the solid surface such as a microbial adhesion andbiofilm formation.[6–8] Thus, the modification of surfaces has been made by applica-tion of various materials.[9] To our knowledge, various works have been conducted onmodification of the wood surface using different techniques such as acidic dyestuff andfixing agent,[10] thermal treatment,[11–14] wet-chemical treatment, corona discharge,and exposure to flame and glow-discharge plasma [15] in order to aggregate value tothis substrate and to remove surface contaminant, to improve the stability and providesuitable surface properties. But there have been no investigations on the effect ofnatural products on cedar wood’s characteristic physicochemical properties. Moreover,anti-adhesion activity [16–18]; antifungal and antimicrobial and many other biologicalactivities of these substances have been reported by several authors,[19–21] but nostudies have been done on their effect on the physicochemical properties of cedarwood, contributing to its preservation against adhesion, microbial deterioration,enhancement of the overall dimensions of its stability and reducing the impact of woodchemical treatment technologies on the environment. In this context, the aim of thisstudy was to investigate the effect of the crude extracts from local T. vulgaris cultivatedon physicochemical properties of cedar wood after pretreatment using contact anglemeasurement.
Materials and methods
Plant material
The aerial parts (leaves and stems) of T. vulgaris L. (Labiateae) were freshly harvestedand collected on October 2012 in the garden of the National Institute of Medicinal andAromatic Plants (NIMAP). The plants were identified and deposited in the herbariumof the NIMAP Taounate-Morocco. The freshly-cut plant was dried in a dryer. Afterdrying the sample was packed in paper bags and stored until the extraction.
Preparation of crude extracts
Maceration extraction
The amount of 80 g of dried and ground aerial part of T. vulgaris was separately mixedwith 800 ml of methanol. The mixture was stirred at room temperature for 2 h, then thesamples were filtered through Gelman GHPAcrodisc (0.45 μm). Finally the crude extractswere then recovered and completely dried in a rotary vacuum evaporator (T ≤ 40 °C).
Ultrasound-assisted extraction
Extractions were carried out in an ultrasonic bath. A batch of 50 g of the dried andground aerial part of this plant was placed in flasks, mixed with 500 ml of methanoland sonicated at 35 kHz frequency and 100W for 45 min at a temperature lower than30 °C. At the end of extraction time the samples were processed as described above formaceration.
Determination of total phenols in the extracts
The total phenolic content was determined using the Folin-Ciocalteu reagent assay,[22]with Gallic acid as standard. Briefly, 20 μl of diluted extracts (prepared in distilled
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water 0.4 mg 4 ml−1) or a standard solution of Gallic acid was added to a test tube con-taining 1.58 ml distilled water. After the addition of 100 μl of Folin-Ciocalteu reagent,the mixture was stirred for 1 min and allowed to stand for 8 min. Then, 300 μl of anaqueous solution of Na2CO3 (7.5% w v−1) was added and the mixture was incubatedfor 2 h at room temperature. The absorbance, relative to that prepared using distilledwater, was measured at 765 nm. The concentration of total phenolic compounds in themethanolic extracts was determined as mg of Gallic acid g−1 of dry plant material byusing the regression equation that was obtained from the calibration curve of the Gallicacid standard.
Substrate preparation
The substrate used was cedar wood. This material was cut into pieces of length 20 mm,thickness 1 mm, and height 10 mm. The roughness of the surface wood pieces was setat 0.8 μm with a rugosimeter. Finally, the samples were cleaned for 15 min in ultrapurewater and then autoclaved for 20 min at 121 °C.
Treatment of wood
The effect of T. vulgaris extracts on surface cedar wood physicochemical characteristicwas performed as follows: A volume of 10 μl of the plant extract studied and diluted indimethylsulfoxide (DMSO 2%) solvent at the concentration of 20 mg mL−1 was appliedby deposit for 20 min at room temperature (25 ± 2 °C) to the surface of the cedar wood.Then, after a good drying and adsorption of product tested, the samples were takendirectly for measurements of the contact angle. Experiments were conducted in dupli-cate.
Contact angle measurements
The contact angle is defined as the angle between the solid surface and a tangent,drawn on the drop-surface, passing through the triple-point atmosphere–liquid–solid.[23] Contact angle measurements for wood substrate before and after pretreatmentwith different crude extracts were performed by using a goniometer (GBX Instruments,France) by the sessile drop method.[24] Three measurements of contact angles weremade on each surface of substrate for all probes using three pure liquids with knownenergy characteristics (Table 1).[25]
Surface tension components and hydrophobicity
The surface wood hydrophobicity was evaluated through contact angle measurementsand by the approach of Van Oss et al. [25]. In this approach, the degree of
Table 1. Surface energy properties of pure liquid used to measure contact angles [25].
hydrophobicity of a given material (l) is expressed as the free energy of interactionbetween two entities of that material when immersed in water (w): ΔGiwi. If the inter-action between the two entities is stronger than the interaction of each entity withwater, the material is considered hydrophobic (ΔGiwi < 0); conversely, for a hydrophilicmaterial (ΔGiwi > 0). ΔGiwi is calculated through the surface tension components ofthe interacting entities, according to the following formula:
DGiwi ¼ �2ciw
¼ �2 ðcLWi Þ1=2 � ðcLWw Þ1=2� �2
þ 2 ðcþi c�i Þ12 þ ðcþwc�wÞ
12 � ðcþi c�wÞ
12 � ðcþwc�i Þ
12
� �� �
where cLW accounts for the Lifshitz-van der Waals component of the surface freeenergy and cþ and c� are the electron acceptor and electron donor parameters, respec-tively, of the Lewis acid–base cAB component, with
cABS ¼ 2 c�S cþS
� �1=2The surface energy components of a solid material (cedar wood) are obtained by
measuring the contact angles of three pure liquids (one apolar and two polar) withwell-known surface energy components,[26] followed by the simultaneous resolution ofthree equations of the following form:
cL Cos hþ 1ð Þ ¼ 2 cLWS cLWL� �1=2 þ 2 cþS c
�L
� �1=2 þ 2 c�S cþL
� �1=2
Results and discussion
Dosage of total polyphenols content of methanolic extracts
The total polyphenols concentration (mg eq AG g−1 methanol extract) on T. vulgarisextracts are determined. It was noted that it varied and was dependent on the methodof extraction. Indeed, the highest content was observed in an extract which wasobtained by ultrasound (191.4 mg Gallic acid/g extract). The lowest amount was givenby T. vulgaris extract which was recovered by maceration (171.4 mg Gallic acid g−1
extract). These results allowed us to conclude that the ultrasonic extraction method pro-vides very important quantities of total polyphenols compared with the classical extrac-tion method. This can be explained by the fact that the phenomenon of cavitationbubbles, which allow a very important mass transfer and easier penetration of the sol-vent to vegetal cells by causing the cells’ disruption, and breaks which had given therelease of cell content into the extraction medium.[27] These findings are in generalagreement with other studies focused on extraction phenolic compounds and whichfound that ultrasound extracted the highest quantities of polyphenols than other classi-cal methods such as maceration and Soxhlet.[28–31]
Physicochemical characterization of the cedar wood surface
The hydrophobicity character, the Lifshitz-van der Waals (cLW), acid–base (surface ten-sion components ΔGiwi, electron donor (c�) and electron acceptor (cþ) parameters ofuntreated and treated wood with the methanolic extracts of T. vulgaris were assessedby contact angle measurement and are given in Table 2.
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The contact angle vis-à-vis the water (θw) can be used as a qualitative method forevaluating the hydrophobicity character of the surface.[32] According to Vogler [33],and the approach of Van Oss [25,34], the degree of hydrophobicity of a given materialis expressed as the free energy of interaction between two entities of that material whenimmersed in water (w): thus, the surface is considered hydrophobic if θw is greater than65° and ΔGiwi is negative and hydrophilic if θw is less than 65° and ΔGiwi is positive.
According to the results presented in Table 2, the contact angle water measurementθw and the free energy of interaction (ΔGiwi) show that the cedar wood surfaceuntreated is qualitatively hydrophobic θw = 86.0 ± 0.2° > 65° and quantitatively withvalue of ΔGiwi = −81.98 ± 0.67 mJ/m2 < 0. These results corroborate those obtained byEl abed et al. [35], evaluating the hydrophobic character of the same material(θw = 82.5 ± 3.9°, ΔGiwi = −58.8 mJ/m2 < 0). A similar surface property wasdemonstrated in other works [36] which was in accordance with funding through awater contact angle θw = 69 ± 2° and ΔGiwi < 0.
For the electron donor (c�) and electron acceptor (cþ) (Table 2), the results demon-strated that electron acceptor cþ of cedar wood untreated was higher than electron-donor character c� which are respectively cþ = 2.03 ± 0.04 mJ/m2 and c� = 0.02 ± 0.01mJ/m2 and are less than Lifshitz-van der Waals parameter cLW = 49.01 ± 0.03 mJ/m2.These findings indicate a basic cedar wood surface confirmed by θF = 36.5 ± 0.3° valueof untreated sample. It is correlated with those found by El Abed et al. and De Meigeret al. [35,36], which reported that the cedar wood had values c� = 5.5 mJ/m2,cþ = 0mJ/m2 and a surface with a basicity value θF = 61.8 ± 5° and a component ofLifshitz van der Waals worth cLW = 37.3 mJ/m2.
In the light of these results, cedar wood studied in the present work presents ahydrophobic character, and a greater electron acceptor than electron-donor character.
Surface free energy and hydrophobic character of wood after treatment with thedifferent extract of T. vulgaris
The contact angle water measurement θw and the free energy of interaction (ΔGiwi) ofcedar wood before and after treatment are listed in Table 2.
As can be seen in these results, the treatment of wood surface with T. vulgarisextract obtained by macerating and ultrasound has changed its degree of hydrophobic-ity, as well as from a qualitative and quantitative point of view. Indeed, the sampleuntreated, which was hydrophobic with θw= 86.0 ± 0.2° values and ΔGiwi = −81.98 ±0.67 mJ/m2, has became more hydrophilic in the case of treatment with ultrasonicextract with values of θw= 18.2 ± 0.2°, and ΔGiwi = 30.62 ± 0.31 mJ/m2.
Compared to treatment with the extract obtained by maceration, it can be noted thatthe treatment with those recovered by ultrasound has caused an important and signifi-cant change in wood physico-chemical characteristics. Indeed the wood has becomemore hydrophilic with the extracts obtained by maceration and ultrasound with contactangle values θw = 29.7 ± 0.3°, ΔGiwi = 17.78 ± 0.48 mJ/m2 and θw = 18.2 ± 0.2°,ΔGiwi = 30.62 ± 0.31 mJ/m2 respectively. This modifying effect of surface propertiesmay be due to the elevated levels of phenolic compounds (191.4 mg/g) of these extractsand especially the different flavonoids (flavones and flavonols) than those recovered bymaceration. These bioactive compounds flavonoids are rich in the hydroxyl group andwere already reported on several works that exhibited a wide range of biological activi-ties such as anti-oxidant, anti-inflammatory, anti-microbial, anti-angionic, anti-cancerand anti-allergic.[37–41] Our results are consistent with those found by Shuangying
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Table
2.Con
tact
angles
values,free
energy
ofinteraction(ΔGiwi)andsurfaceenergy
compo
nentsof
surfacecedarwoo
dbefore
andaftertreatm
ent.
Sub
strate
Con
tact
angles
(°)
Surface
energy
:compo
nentsandparametersmJ/m
2)
θ w(°)
θ F(°)
θ D(°)
cLW
cþc�
ΔGiwi
Untreated
(con
trol)
86.0±0.2
36.5±0.3
14.8±0.1
49.01±0.03
2.03
±0.04
0.02
±0.01
−81
.98±0.67
Treated
with
extractob
tained
bymaceration
29.7±0.3
20.2±0.2
11.8±0.1
49.61±0.03
0.15
±0.01
44.76±0.3
17.78±0.48
Treated
with
extractob
tained
byultrasou
nd18
.2±0.2
21.8±0.2
51.4±0.4
33.38±0.25
2.03
±0.02
53.80±0.3
30.62±0.31
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et al. [10], who reported that wettability of a birch wood surface modified by acidicdyestuff and fixing agent increased significantly with the moisture content and theextension of time. Indeed, the samples treated were decreased their hydrophobic charac-ter (θw ranged from 29.5° to 40.5°) than that of the untreated sample with θw = 115°.Similar trends were also observed in the case of tiger wood modified by microwaveplasma, which was more hydrophilic than the control sample.[42] It has shown that sur-face free energy rises slightly for a longer treatment time. Moreover, the findings of thiswork are in contradiction with the results obtained with the modification-generatedsurfaces of northern red oak wood treated with a copper ethanolamine solution, whichshowed that the hydrophobic character of the CuEA (0.2% Cu), CuEA (0.4% Cu) andCuEA (1.0% Cu) treated was significantly lower than that of the control sample.Indeed, the contact angles of water on the copper-treated wood surface wereθw = 123.3 ± 3.5°, θw = 124.6 ± 3.0° and θw = 120.8 ± 2.9° respectively, whereas it wasθw= 105.1 ± 3.8° on the untreated wood surface.[43]
The treatment of the cedar wood surface by a natural product from T. vulgarisreduced greatly its hydrophobicity which has become very hydrophilic. This modifica-tion may be related to the chemical composition of these extracts rich in polyphenols.These latter are polyhydroxy, polar compounds and known by their hydrophilic charac-ter compared to essential oils which are renowned for their hydrophobic behavior.
Electron donor (c�) and electron acceptor (cþ) character of cedar wood aftertreatment with T. vulgaris extracts
The results of the effect of the crude extract tested on the electron donor (c�) and elec-tron acceptor (cþ) character of cedar wood are presented in Table 2.
As can be noted from this table, the material treated with extract obtained by mac-eration has given a similar value of the component Lifshit-Van Der Waals (cLW =49.61 ± 0.03 mJ/m2) to that of untreated sample. Moreover, electron donor was grow-ing strongly (c� = 44.76 ± 0.3 mJ/m2) than the electron acceptor has been canceled.
Regarding the treatment with the extract obtained by ultrasound, the results showan important effect on electron acceptor-donor character. Indeed, on the one hand, thevalue of the component Lifshit Van Der Waals decreased to a value of cLW = 33.38 ±0.25 mJ/m2 while it is cLW = 49.01 ± 0.03 mJ/m2 for untreated wood. On the otherhand, the electron donor character was increased significantly in value c� = 53.80 ±0.3 mJ/m2 compared to untreated wood which is c� = 0.02 ± 0.01 mJ/m2. However, theelectron acceptor character was the same.
These findings were corroborated with the results obtained by Haihong and Pascal[43], which demonstrated that after PVC–copper amine treatment of red oak (Quercusrubra) wood the electron-acceptor (acid) (cþ) and electron-donor (base) (c�) surfacecomponents were increased with treatment. In fact, the electron-donor component (c� =11.0 mJ/m2) of the 0.4 wt % Cu-treated oak surfaces was 11-fold higher, and the elec-tron acceptor character (cþ = 6.8 mJ/m2), was about 9-fold higher than that of the con-trol sample (c� = 0.9 mJ/m2, cþ = 0.7 mJ/m2). It was also noted that the Lifshitz–vander Waals force component was reduced in treating wood compared to those untreatedsurfaces. The same results were found by Mohammed-Ziegler et al. [44], which showedthat the electron donor component (cþ = 5.4 mJ/m2, c� = 3.9 mJ/m2) obtained on Euro-pean wood samples (oak and cloves respectively) treated with chlorotrimethylsilane(CTMS) were higher than the control wood. With regard to election acceptor (cþ) wasrelatively constant after treatment.
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In conclusion, the physicochemical properties in terms of hydrophobicity anddonor/acceptor characters of cedar wood surface are largely influenced by the treatmentwith T. vulgaris extracts. In fact, the samples treated showed the hydrophilic characterand had less contact angle value than that of untreated cedar wood. Moreover, it can benoted that modification degree was dependent on the type of extraction method. Other-wise, the treatment with both types of extracts of T. vulgaris made surface wood moredonor than electron acceptor. Generally, this important effect attributed to these prod-ucts may be due to its wealth of polyphenolic compounds which are known by theirhydrophilic character.
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