The
Nowadays, the development of degradable composite reinforced with biofibers is of crucial importance. Biofibers such as natural fibers offer several advantages: low density, low cost, environment protection and high specific mechanical performance, which makes it a substitute for synthetic glass, carbon and other synthetic fibers. Biocomposites were developed in all sectors of society, particularly in the aeronautics, automotive and wood industries etc. Recently, high-performance composite materials using biofibers have been developed [
In the interest of making composites fully bio-based, research has been carried out to substitute synthetic hardeners with biohardeners in tannin resins. A totally biohardeners derived from exudate extract of African trees
A totally bio and high-performance material could be less toxic to humans and environmental protection. The objective of this paper is to study the performance of a totally biocomposite based on a unidirectional woven mat and bio tannin adhesive.
The
The
The exudates of
The bark of
In an aqueous solution containing 40% tannin of
The fiber mats of 400 × 350 mm2 size was made using a special device consisting of a rectangular frame made of solid wood, on which spikes are arranged at intervals of 5 mm. The weaving device used for process is showed in
The pre-weighed carpets were impregnated with the resin by Scarf Impregnation (manufactured by Mathis, Zurich, Switzerland). The Passage was carried out six (6) times under a roller pressure of 4 MPa. The impregnation is considered correct when the resin reaches the fibers in the heart of the carpet. The pre-impregnated fabrics were weighed and placed under the hood at a temperature of 25°C for 5 hours and then weighed again.
The pressing of the biocomposite was done at 180°C, on a GOTTFRIED JOSS hydraulic press in tree steps during 8 min (4 min at 2 MPa pressure, 2 min at 1 MPa pressure and 2 min at 0.5 MPa pressure)
The biocomposite obtained contained 51% fiber and 49% resin.
About 2 mg grinded powders of fine tannin extract was placed on the diamond/ZnSe crystal of the analytical device and contact is achieved by applying a hand force of approximately 150 N (manual force) on the sample. Each extract was scanned registering the spectrum with 32 scans with a resolution of 4 cm−1 in the range between 600 and 4000 cm−1. The sample is scanned five times and the average of these spectra is studied in the fingerprint (4000 and 600 cm−1) [
Tannin for Laser Desorption Ionization Time-of-Flight (MALDI-TOF) mass spectrometry analysis was prepared by first dissolving 5 mg of tannin powder in 1 mL of a 50:50 v/v acetone/water solution. 10 mg of this solution was added to 10 µL of a 2-5-dihydroxy benzoic acid (DHB) matrix. To improve ion formation, NaCl was added to the matrix. The two previous solutions are mixed in a proportion of 50:50 and about 0.5 to 1 µl of this mixture is taken and placed on a wafer (around a spot). after evaporation of the solvent for a few minutes in the open air, the wafer is introduced into the spectrometer for further processing. The spectra were recorded in a KRATOS compact MALDI AXIMA PERFORMANCE TOF 2 instruments. The software MALDI-MS was used for data treatment [
5 g of liquid resin was introduced in a tube and placed in a water bath, maintained at boiling temperature (100°C) at normal atmospheric pressure. Spring has been inserted into the test tube and moved rapidly up and down. The gelation time is measured by a stopwatch. The test is performed in three times and the mean value is reported [
To determine the viscosity, used a DV-II+ viscometer from Brookfield Engineering with a n° 5 spindle. The rotation speeds were 10, 20, 50, 100 rpm and the ambient temperature was 20°C [
The tests were carried out on a METTLER TOLEDO TMA/SDTA840 machine. About 25–30 mg of resin is placed on two Plywood with dimensions 17 × 5 × 1 mm and then glued. Place in the oven of the TMA Analyzer for testing. Samples are tested in non-isothermal flexure between 30°C and 250°C at a heating rate of 10°C/min. The resin was analyzed by three-point bending using an earlier technique [
where: E is Young’s modulus, L = the length of the span tested, b is the width and h the thickness of the specimen, F is the force exerted on the tested assembly, fwood and fadhesive are the deflections that have been proven to be constant and reproducible [
The tenacity of bundle (mass m = 0.03 g, length 20, 30, and 50 mm) tested using the Instron 4206 machine according to NF G07-307 [
where L is fiber bundle length under pre-voltage (mm), l: length of the specimen measured between the jaws under pre-tension (mm), m: the mass of the specimen of length l (mg), M mass of the bundle (Tex), F is the breaking strength of the sample (cN), R is the tenacity (cN·Tex−1), A is breaking elongation (mm) and E is relative elongation at break (%).
Ten (10) specimens (ep1 to ep10) of 150 × 20 mm were tested according to NF ISO 527-4/2/1 [
where: F: strength causing a displacement (N), A: Area of the initial cross-section of the test piece (mm²), L0: length of the specimen (mm), ΔL0: length of the test piece between the reference marks (mm).
The plots were drawn and using MATLAB software which allowed us to deduce the Young’s Modulus (MOE), ultimate (Rm), yield (σy) and yield strain (εy).
Ten (10) specimens of 80 × 25 mm were tested according to NF EN ISO 178 [
where: σ: normal stress (MPa): relative strain, f : deflection measured during the test for each load (mm), P: strength causing a displacement (N), L: between supports (mm), b: width of the sample (mm), h: of the sample (mm).
The analysis of MALDI-TOF spectra of extract
Pics (g/mol) | Monomer | Remark |
---|---|---|
192 | gallic acid + Na (+2H) | Monomer |
198 | Glucose + H2O | Monomer |
230 | Chalcone + Na (-H) | Flavonoid monomer |
294 | Catéchin tétraprotoneted | Flavonoid monomer |
316 | Catéchin tétraprotoneted + Na | Flavonoid monomer |
368 | Chalcone + glucose (-H2O) | Flavonoid-glucose dimer |
397 | Chalcone + gallic acid + Na | Flavonoid + fragment |
408 | Chalcone + glucose + Na | Flavonoid-glucose dimer |
412 | Chalcone dimer (-2H) | Flavonoid dimer |
440 | Chalcone dimer triprotoneted + Na | Flavonoid dimer |
456 | Gallocatéchin gallatte (-2H) | Flavonoid monomer |
470 | Quercétine gallate | Flavonoid monomer |
504 | Quercétin diprotoneted + glucose + Na | Flavonoid-glucose dimer |
508 | Epigallocatéchin diprotoneted + glucose + Na | Flavonoid-glucose dimer |
522 | Catéchine tétraprotoneted + Chalcone + Na | Flavonoid dimer |
526 | Quercétine + Chalcone + Na (-3H) | Flavonoid dimer |
550 | Epigallocatéchine + Chalcone + Na (+OH) | Flavonoid dimer |
560 | Catéchine dimer (-H2O) | Flavonoid dimer |
580 | Catéchine dimer | Flavonoid dimer |
602 | Catechin dimer + Na | Flavonoid dimer |
610 | Epigallocatechin dimer | Flavonoid dimer |
622 | Quercetin dimer + Na (-2H) | Flavonoid dimer |
624 | Quercetin dimer protoneted + Na | Flavonoid dimer |
656 | Gallocatechin galate + glucose + Na (-H) | Flavonoid dimer |
678 | Gallocatechin galate + Chalcone (+OH) | Flavonoid dimer |
700 | Chalcone dimer + catéchine (-2H) | Flavonoid trimer |
722 | Chalcone dimer + catéchine + Na (-H) | Flavonoid trimer |
746 | Epicatechin gallate diprotonated + Quercetin | Flavonoid dimer |
778 | catechin dimer + glucose + Na | Flavonoid trimer |
784 | catéchin dimer + Chalcone | Flavonoid trimer |
813 | Chalcone Protonated+ Quercétine + Epigallocatechin + Na | Flavonoid trimer |
829 | Chalcone tetramer (-3H) | Flavonoid tetramer |
832 | Chalcone tetramer | Flavonoid tetramer |
854 | Catechin trimer (-OH) | Flavonoid trimer |
892 | Gallocatechin galate protonated + Chalcone dimer + Na+ | Flavonoid trimer |
915 | Epigallocatechin trimer protonated | Flavonoid trimer |
945 | Chalcone trimer + Epigallocatechine + Na | Flavonoid tetramer |
961 | Epigallocatechin+ Gallocatechin galate + glucose + Na | Flavonoid dimer+glucose |
965 | Epicatechin gallate + Quercetin + Chalcone + Na (-3H) | Flavonoid trimer |
970 | Epicatechin gallate + Epigallocatechin + Chalcone + Na (-3H) | Flavonoid trimer |
977 | Epicatechin gallate tetraprotonated + Epigallocatechin + Chalcone + Na | Flavonoid trimer |
994 | Quercetin + Chalcone + catechin + Na (-H) | Flavonoid trimer |
1014 | Chalcone tetramer + gallic acid + Na (-H) | Flavonoid tetramer+fragment |
1048 | Epicatechin gallate + Quercetin + Catéchine + Na (-3H) | Flavonoid trimer |
1075 | Gallocatechin gallate + Quercétin dimer + Na (-4H) | Flavonoid trimer |
1077 | Gallocatechin gallate + Quercetine dimer + Na (-2H) | Flavonoid trimer |
1082 | Gallocatéchin gallate + Epigallocatéchin + Quercétine + Na | Flavonoid trimer |
1097 | Gallocatechin gallate + Epicatechin gallate + glucose + Na | Flavonoid dimer+glucose |
1109 | Catechin dimer + Quercetin + Chalcone diprotonated + Na | Flavonoid tetramer |
1109 | Catechin dimer + Quercetin + Chalcone diprotonated + Na | Flavonoid tetramer |
1113 | Quercetin dimer + Chalcone + catechin + Na (-2H) | Flavonoid tetramer |
1244 | Catechin dimer + Chalcone + Epicatechin gallate + Na (-H) | Flavonoid tetramer |
1388 | Gallocatechin gallate trimer + Na(-3H) | Flavonoid trimer |
1430 | Quercetin tetramer + Chalcone + Na (-H) | Flavonoid tetramer |
1520 | Quercetin dimer + Epigallocatechin dimer + catechin + Na (-H) | Flavonoid pentamer |
1534 | Quercetin trimer protonated + Epigallocatechin dimer + Na | Flavonoid pentamer |
1562 | Epigallocatechin pentamer + Na (+OH) | Flavonoid pentamer |
1568 | Epicatechin gallate dimer triprotonated + Gallocatechin galate + Chalcone + Na | Flavonoid tetramer |
1694 | Gallocatechin gallate trimer + Epigallocatechin protonated + Na | Flavonoid tetramer |
The results indicate that Chalcone is the major constituent of the tannin of
The analysis of the ATR FT-MIR spectrum in the region between 4000 and 600 cm−1 (
Pic (ppm) | Assignment |
---|---|
618 | Aromatic torsion, out-of-plane C-H bending |
1448 | C-H Aromatic bending, tetrahedral carbon, C-O stretching, and C-OH deformation |
1606 | Vibratory movements of the C = C groups in the aromatic rings |
3134 | O-H carboxylic acids |
The gel time was measured at the natural pH (pH = 5.4). It gels in 660 s, faster than pine resin (1490 s) (with the same
The curve in
The standard deviations of different fibers lengths serials (L = 20 mm, 30 mm, 50 mm) are calculated, their values are mentioned in
Length | L = 20 mm | L = 30 mm | L = 50 mm |
---|---|---|---|
65.41 | 41.04 | 33.86 | |
1.3 | 0.91 | 0.7 |
After weaving we obtain unidirectional mat of
The different specimens show similar behavior, the average breaking strength is 4.6 kN. There is a slight dispersion of the breaking strength (standard deviation 0.64) This would be mainly due to the existence of defects (air bubbles) caused by the pressing during the curing process (
Microstructural analysis of section (
The 3 points bending behavior of the biocomposite represented in
The
The LERMAB of the University of Lorrain. Also, A. Bobbo Director of the Advanced Vocational Training Centres (AVTC) of Douala and Nzogning F. head of Mechanics Department (AVTC Limbe), for equipment and extractions.