This work presents the physical and thermal characterization of the dura palm kernel powder of Cameroon for their use as fillers for polymers composites. The powders of palm kernel were obtained using a percussion grinder mill with an industrial microniser which allowed obtaining a powder less than 50 μm with an apparent density between 0,505 ≤ ρ ≤ 0,680 g/cm 3 at 1.56 of relative humidity. The infrared of the powder of palm kernel shows the presence of phenols groups with a large band around 3341 cm -1, -C-H at 2917.02 cm -1 and -C-O at 1040 cm -1 as the main peaks. The polyvinyl chloride of infrared obtained shows the presence of -C-Cl, -CH 2 and CH as the mains peaks. The infrared of 12.5% of palm kernel powder with polyvinyl chloride shows an increase of the CH 2 and CH bonds and a decrease of the -OH bonds. Thermogravimetric analysis and differential scanning calorimetric analysis of powders, polyvinyl chloride and mixture showed that the mixing powders are intermediate between the polyvinyl chloride and palm kernel powder. The powder decreased the phase temperatures of the mixture from 98.58 ℃ to 95 ℃ for the glass transition temperature and from 515℃ to 459 ℃ for the crystallization temperature. The thermogravimetric curves of palm kernel powder and polyvinyl chloride have showed that these materials lose their different masses in three different phases, and the one of composite (mixture of polyvinyl chloride with 12.5% of palm kernel powder) in two different phases.
Polyvinyl chloride (PVC) is one of the most important plastics used in the world today. They are mostly found in the packaging, electricity, electronics, electromechanical and building sectors [
The palm kernel shell dura comes from palm oil, plant of the family ARECACEAE (palmae) of its scientific name Elaeis guinensis Jacq, referenced by comparison to the botanical collection of TAMAKI MARUHASHI of the national herbarium of Cameroon. This variety of palm oil is less exploited because of its low yield of oils that is the peculiarity of its exploitation [
It should be added that the palm oil sector in the world [
Palm kernel husks have been investigated in its use as fuel for cupolas [
Palm kernel shells are available not only in Cameroon, but also in abundance in Africa, the Mediterranean and in Southeast Asia [
The present study aims to set up a practical, experimental methodology to transformed nut shells into powder. Characterize the powder obtained and then use it as fillers for polymers in the production of plastics. It should also be noted that in the literature we have read so far no work of this kind on the use of hulls of palm kernels as fillers has been realized.
The hulls of dura palm kernel were collected in Cameroon, in the littoral region and Moungo department. They were identified by comparison with the botanical collection of TAMAKI MARUHASHI N˚103 recorded in the national herbarium of Cameroon under N˚47794/HNC. These hulls come from the palmoil of the family ARECACEAE. Its scientific name is Elaeis guinensis Jacq. Determavit TADJOUTEU Fulbert HNC on 04/05/2018. The
The raw palm kernel shells were previously dried until constant mass. The hulls were first crushed using a Retsch brand mill, type SN 100 of series No. 82508001 [
1) Thermogravimetric analysis
Thermogravimetric coupled with differential scanning calorimetry analysis was performed using a LINSEIS branded device connected to a computer with
reference mark | Designation | observations |
---|---|---|
1 | Base of the machine | Flat iron of (30 × 20 × 6) mm |
2 | Three-phase asynchronous electric motor | 7.5 HP |
3 | Inlet Hopper Hull | Steel sheet 1.5mm thick; capacity 20 litres |
4 | Crusher | Z 30 CDNW 6 - 4 - 2 |
5 | Grinding chamber | Blue sheet 12 mm thick |
6 | Mechanical sieve for crushing | Blue sheet thickness 3mm, opening holes 1.5 mm hole |
7 | Mechanical sieve for grinding | Blue sheet thickness 2 mm, hole opening 0.5 mm |
8 | Crushing efficiency | 61 kg/hour |
9 | Grinding yield | 47.25 kg/hour |
10 | Control of the machine | Electric box secured with automatic stop during an overload and an increase in temperature of the engine. |
embedded software for data acquisition. A 150 mg capacity aluminum oxide crucibles were used with a; the speed of the measurement is variable and the combustion gases are nitrogen.
PVC that used was collected from the company DANSUK INDUSTRIAL CO., LTD under the name Vinova and batch number S6830 [
2) Fourier transformed infrared analysis
Fourier transform infrared spectroscopy (FT-IR) was performed using the Nicolet iS5 IR spectrometer.
The dried palm kernel shells were poured into the hopper of the mill and are conveyed into the crushing chamber through the opening of the hatch. These are sucked by the centrifugal effect of the rotational movement of the mobile crusher which projects them on the walls of the grinding chamber. The centripetal force (Equation (1)) of the mobile crusher projects the hulls onto the stationary mills of the machine thus providing the necessary energy for their fragmentation.
F = mω2R (1)
The crushed hulls pass through the mesh size 1.5 mechanical sieves and are recovered. Subsequently, a sieve of 0.5 mesh is mounted in place of the previous to ensure the crushing of kernel shell previously crushed. The milled powder is transported to a micronizer which refines the powder and gives the desired grade (50 μm). An oven heated to 103˚C for 24 hours allows dehumidification. The appropriately dried powder is immediately stored in plastic bags.
1) Density
Apparent density: the method described by Ernesto de la Torre Chauvin in 2015 [
ρ v = m i v i (2)
where mi = mass of the powder and vi = volume of the powder.
Wetted density: the method described by Ernesto de la Torre Chauvin in 2015 [
ρ m = ρ water ( m 2 − m 0 ) ( m 2 − m 0 ) − ( m 3 − m 1 ) (3)
2) Granulometry of micronized palm kernel shell powders
The particle size is sieved using an Afnor 50 μm aperture calibrated sieve in order to ensure the wear of the microniser jaws.
3) Moisture content of powder
To evaluate the moisture contained of powder, we used the method described by Dietsch et al., 2014 [
The moisture content (MC) was calculated using the Equation (4) below.
M C = m h − m d m d × 100 (4)
where mh is the wet mass of powder, and md the anhydrous mass of the powder
4) Thermal characterizations
The thermal behavior of the shell powder is obtained by interpretation of the TG and DSC thermograms performed by the LINSEI instrument of the Physico-chemistry of Mineral Materials Laboratory, Faculty of Science, University of Yaounde 1―Cameroon. The heating rate is 10˚/min. The flue gas is oxygen. The crucible is alumina oxide of capacity 150 mg; the loading mass is 100mg; the initial heating temperature is 20˚C. We were given a thermogram TG coupled DSC with data records.
5) Fourier transformed infrared analysis
The FTIR analyses were carried out using the iS5 spectrometer. The spectra were acquired in the range of 4000 to 480 cm−1 at a resolution of 4 cm−1. Characteristic absorptions bands of the processed composites were registered.
6) PVC
The analyses performed on the hulls were also made on PVC under similar conditions.
7) PVC mixture with 12.54% of palm kernel shell powder before shaping.
According to literature, mixing powders (PVC + filler + additives) have to go through analysis before shaping [
A mixture of 33.33 kg (81.17%) of PVC, 1.30 kg (3.17%) of stabilizer, 0.70 kg (1.70%) of lubricant, 0.48 kg (1.16%) of plasticizer, 0.09 kg (0.23%) of titanium dioxide, 0.01 kg (0.03%) of black charcoal, 5.15 kg (12.54%) of hull powder, corresponding total of 41.07 kg equivalent to 100% of mixture. The different percentages of the additives were chosen according to the standard applicable in the Cameroon company. The mixture is put in a mixer (steaming of the mixture) to make them perfectly homogeneous. A sample is taken and a thermogravimetric and differential scanning calorimetry analysis is done with the same apparatus as described before and under the same conditions.
Apart from the analyses of thermogravimetric and differential scanning calorimetry, all the manipulations were done 6 times and the means of the six tests were expressed with standard deviation.
The passage of palm kernel shell in a crusher-mill and then in an industrial micronizer helped to transform palm kernel shell of dura palm into palm kernel powder with a size smaller than 50 μm [
Density is an important parameter for plastic composite in view to obtained material that is less heavy. The average values obtained in the case of apparent density is: ρ v = 0.680 ∓ 0.013 g / cm 3 . This proves that there is not enough vacuum between the powder seeds. This density can be compared to the density of plant fibers such as bagasse [
The average values obtained in the case of wet density is: ρ m = 0.505 ∓ 0.006 g / cm 3 . This result proves that the shell powder of dura is hydrophilic probably due the presence of hydroxyls group that can fix water molecules via the formation of hydrogen bounds. The real density ρ r of the palm kernel powder shell is between the two densities obtained 0.505 ≤ ρ r ≤ 0.681 g / cm 3 .
When measuring masses for mixing (steaming), the masses are measured poured into breasts. During shaping, the resin melts and the powder absorbs the resin to crystallize the materials. The results obtained, allow saying that the density of the kernel powder from Cameroon is between 0.505 and 0.680 g/cm3. In literature, it is found that the density of some polymers is: 1. 38 to 1. 41 for PVC), 0.89 to 0.93 for PE, of 0.85 to 0.92 for PP and 1.12 to 1.16 g/cm3 for Nylon 6.6. The values of the density of palm kernel powder obtained, compared to the density values of some plant fibers used to reinforced polymers such as hemp (1.5 g/cm3), feather (0.9 g/cm3), Wool (1.3 g/cm3), sisal (1.3 - 1.5 g/cm3) [
On the other hand, the hydrophobic behavior of the shell powder remains unchanged after shaping. As a result, the rate of absorption and desorption of fluids is washed away [
The means value obtained from these results showed the moisture content of palm kernel powder is 1.6% ± 0.1%. From this moisture content value, it appears that the shell powder does not have enough water for hydration and that this measurement was made when the powder had just been dried to be ground. It will not be doubtful to find such a high humidity level, as the result brought by Ernesto de la torrechauvin in his thesis [
On
In
ring or carboxyl group of lignin. The peak between 1300 - 1000 cm−1 and those of 1243 - 1044 cm−1 could be attributed to C-O stretch of alcohols, esters or ethers. These results are in agreement with data found in literature concerning palm kernel shell. Kundu et al. 2015 [
The FT-IR analysis of polyvinyl chloride shows peak intensities at 2909, 1425, 1325, 1253, 1095, 962,825 and 607 cm−1. The peak intensity at 2909 cm−1 can be attributed to the vibration of C-H. The intensity at 1425 cm−1 can be attributed to -C-H deformation. The intensity at 1325 cm−1 can be attributed to -CH2 deformation. The intensity at 1253 cm−1 can be attributed to -C-H rocking mode or out of plane angular deformation of -C-H. The intensity at 962 cm−1 can be attributed to trans -C-H wagging mode or out of plane trans deformation. The intensity at 825 cm−1 can be attributed to -C-Cl bond stretching. The intensity at 607 cm−1 can be attributed to -CH cis wagging mode. These peak intensities are in accordance with data found in literature concerning PVC [
The FT-IR analysis of polyvinyl chloride with 12.54 palm oil kernel mixture shows different intensities peak. The peak intensity at 3301.52 cm−1 can be attributed to the vibration of -O-H. The intensity at 2917.02 and 2849.13 cm−1 can be attributed to -C-H. The intensity at 1424.71 cm−1 can be attributed to -C-H rocking mode or out of plane angular deformation of -C-H. The intensity at 1424.71 cm−1 can be attributed to trans -C-H wagging mode or out of plane trans deformation. The intensity at 1041.05 cm−1 can be attributed to -C-O. The intensity at 874.56 cm−1 can be attributed to C-Cl. We can note a decrease in intensity at 3301 cm−1 of the -O-H groups of the palm oil kernel which can means that there is a new bond that was create between the PVC and palm oil kernel. The same observation was done at 1041 cm−1 with the increasing intensity compared to PVC and decreased compared to palm oil kernel. At 2917, 1424, 1253, we observe a strong increase of intensity of the groupings. All these increases, decreases and creations of grouping may imply an interaction between palm kernel nuts powder with PVC [
In
In this figure, it appears that the raw material exhibits three degradation phases:
1) Dehydration: the degradation starts at 101˚C and leads to about 1.13% of mass loss. This phase corresponds to linked water evaporating from the material [
2) Hemicellulose and Cellulose degradation: the degradation starts at 189˚C, end around 380˚C and lead to about 48.38% of mass loss. In this phase hemicellulose decompose between 189˚C and 300˚C, the cellulose decompose between 300˚C and 380˚C. When the two polymers are degraded, the material re-equilibrates by forming others phases and releasing a calcinate.
3) Lignin degradation: the degradation starts around 400˚C and leads to about 20.82% of mass loss. The entire bonds are broken, a large part of the material is pyrolyzed and only the ashes remain.
These results are in agreements with the results obtained by others researchers [
The DSC shows an endothermic peak of heat at 101˚C. During the degradation of cellulose and hemicelluloses, DSC presents a peak at 360˚C and during the degradation of lignin there is another peak at 496˚C. It can be also note that the ignition temperature is 200˚C and the burnout temperature is 580˚C for the raw palm kernel shell.
As the aim of this work is to use the palm kernel shell as filler, it is necessary to study the behavior of palm kernel shell between 0 and 250˚C. The ideal processing temperatures of several polymers are between 80˚C for polyethylene and 250˚C for polytetrafluoroethylene or between 170˚C and 205˚C for rigid PVC that we studied [
The
Similarly,
Characteristic parameters:
The PVC used for this study comes from DANSUK INDUSTRY4. It was delivered to us in a 25 kg bag in the form of a white powder (KN 500).
The TG and DSC of raw PVC are presented in
three main phases of degradation of the raw PVC:
1) Dechlorination phase: the degradation starts at 220˚C and leads to about 64.25% of mass loss. This phase corresponds to the degradation of HCl and the formation of polyene structure.
2) Condensation phase: this phase starts at 420˚C and end at 470˚C and leads to about 7.01% of weight loss. In this phase, a part of polyene is degraded and the other part of the polyene molecules rearrange through cyclization reactions and crosslinking by forming aromatic hydrocarbons and ashes.
3) Fragmentation phase: this phase starts at 470˚C and leads to about 25.38% of weight loss. The aromatic compounds formed before are degraded, all the material being degraded, only the ashes remain.
These results are in agreements with the results obtained by others researchers [
The DSC shows an endothermic peak of heat at 278˚C. During the degradation of polyene and aromatic compounds an exothermic is observed at 440˚C and 515˚C. It can also be noted that the ignition and the burnout temperatures for the raw PVC are around 220˚C 560˚C respectively.
The DSC of PVC was also done in order to determine the glass transition temperature (Tg). This is an important parameter for polymer characterization because it permits to evaluate the plasticizing effects of substances when it is added on polymers. The curve of the DSC of PVC is presented in
As we can observe in
After the study of raw palm kernel shell and PVC, we made a composite loaded
at 12.54% with palm kernel shell. The
The
1) Dehydration: the degradation starts at 98˚C and leads to about 1.02% of mass loss. This phase corresponds to the dehydration of the material.
2) The second phase of degradation starts around 235˚C and end around 360˚C, consist of the dechlorination of PVC, the degradation of cellulose and hemicelluloses structures. This phenomena leads to a mass loss of 64.21%. In this phase there is also a rearrangement of the composite and production of the ashes. Compared with the TG of palm kernel shell and PVC at 360˚C, there is a decrease in mass equivalent to 64.21% of the dry mass against 64.25% for PVC and 48.48% for palm kernel shell. This influence is weak because the loading rate of the palm kernel shell powder is low, hence the behavior of the TG tend towards the TG of PVC.
3) The third phase of degradation starts at 360˚C and leads to 20.82% of weight losses. This phase consist of degradation of lignin and residual residue and the production of ashes that shows the total combustion of the composite. We can also note that the ignition temperature is around 98˚C and the burnout temperature is 540˚C for the composite.
The DSC curves (
By comparing the different DSC, it can be observed that palm kernel powder absorbs more heat than PVC. This phenomenon can be justified by heat absorption
of carbon [
One of the important parameters of a material is its degradation as a function of the increase or decrease of the temperature. After the study of the TG and DSC of palm kernel shell, PVC and composite, Hence, the next and important stage, was to see how the material absorbs heat during the weight loss. The result is presented in
From the
In
Glass transition temperature (Tg) | Melting temperature (Tm) | Crystallization start temperature (Tec) | Peak crystallization temperature (Tc) | Ashes start temperature (Ta) | |
---|---|---|---|---|---|
PVC | 98.56˚C | 147.84˚C | 455.56˚C | 519.5˚C | 556˚C |
Composite | 95˚C | 142.5˚C | 368˚C | 459˚C | 558˚C |
been a decrease in the glass transition temperature of PVC. It can thus be concluded that the palm kernel shell reinforces the plasticizing effect like all natural plasticizers. Then, we obtained the crystallization start temperature at 455˚C for the PVC against 368˚C for the composite, which gives the crystallization peak temperature of 519˚C for the PVC against 495˚C for the composite. Finally the ash is started to be obtained around 556.56˚C for the PVC against 558˚C for the composite.
In this study we transformed palm kernel shell to palm kernel powder. We have studied the possibility of using palm kernel powder as filler for polymers and using PVC as polymer. The results show us that the load of palm kernel shell powder greatly reduces the phase temperatures of the polymers. In the same way, the palm kernel shell load decreases the mass loss of the PVC loaded up to the melting point of the PVC, but in the crystallization phase of PVC, the loss of mass decreases to its degradation. From the thermogravimetric curve of palm kernel shell, we observed three levels of degradation of raw matter with 1.13%, 48.38% and 20.82% of weight loss respectively. These different mass losses have attributed to the dehydration (1.13%), hemicelluloses and cellulose (48.38%) and lignin (20.82%). The composite made by filler PVC with 12.5% of palm kernel shell permits us to conclude that, the behavior of composite is between the behavior of PVC and palm kernel shell powder. The diminution of glass transition temperature ensures us that we can use the palm kernel shell powder to produce new material with news performances.
Djomi, R., Meva’a, L.J.R., Nganhou, J., Mbobda, G., Njom, A.E., Bampel, Y.D.M. and Tchinda, J.-B.S. (2018) Physicochemical and Thermal Characterization of Dura Palm Kernel Powder as a Load for Polymers: Case of Polyvinyl Chloride. Journal of Materials Science and Chemical Engineering, 6, 1-18. https://doi.org/10.4236/msce.2018.66001