E-ISSN:2583-9152

Research Article

TGA and Thermal Kinetics

Journal of Condensed Matter

2023 Volume 1 Number 1 Jan-Jun
Publisherwww.thecmrs.in

TGA and Thermal Kinetics of Raw Calotropis Procera Fiber Reinforced PF Composites

Sharma R1*, Joshi A2, Dimple3, Singh G4
DOI:10.61343/jcm.v1i01.6

1* Ritika Sharma, Department Of Physics, Govt Dungar College, Bikaner 334001, Rajasthan.

2 Akshay Joshi, Department Of Physics, Govt Dungar College, Bikaner 334001, Rajasthan.

3 Dimple, Department Of Physics, Govt Dungar College, Bikaner 334001, Rajasthan.

4 G P Singh, Department Of Physics, Govt Dungar College, Bikaner 334001, Rajasthan.

Natural fibre-reinforced composites are used in various structurally designed goods, from civil engineering to the production of automobiles, thanks to qualities like minimal density, a favourable aspect ratio, biodegradability, and ease of fabrication. The thermal behaviour of natural fibres and composites has also been researched. The thermal degradation kinetics characteristics of composites made with phenol formaldehyde resin and reinforced with untreated Aak fibre with varying fibre loads have been determined using thermogravimetric analysis (TGA). The Flynn-Wall procedure determined each component and composite material's precise apparent activation energy (Ea). Varying fibre load (5, 10, 15, 20 wt.%) was used to reinforce PF resin, and TGA was taken for all composite samples. By observing TGA data composite with 15 wt% fibre load shows maximum thermal stability, it can also be concluded that the thermal stability of prepared composites increases with increasing fibre load. After 15 wt%, it starts to decrease.

Keywords: Untreated Aak fibre, PF resin, TGA, Chemical kinetics for TGA

Corresponding Author How to Cite this Article To Browse
Ritika Sharma, , Department Of Physics, Govt Dungar College, Bikaner 334001, Rajasthan, .
Email: 		Sharma R, Joshi A, Dimple, Singh G, TGA and Thermal Kinetics of Raw Calotropis Procera Fiber Reinforced PF Composites. J.Con.Ma. 2023;1(1):29-33.
Available From
https://jcm.thecmrs.in/index.php/j/article/view/6

Manuscript Received Review Round 1 Review Round 2 Review Round 3 Accepted
2023-05-03 2023-05-12 2023-05-19 2023-05-25 2023-06-01
Conflict of Interest Funding Ethical Approval Plagiarism X-checker Note
None Nil Yes 20.99

© 2023by Sharma R, Joshi A, Dimple, Singh Gand Published by Condensed Matter Research Society. This is an Open Access article licensed under a Creative Commons Attribution 4.0 International License https://creativecommons.org/licenses/by/4.0/ unported [CC BY 4.0].

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Introduction

Recent decades have seen a resurgence in interest in natural materials, such as cellulose-rich fibres taken from cultivated plants, often known as lignocellulosic fibres, and their polymer composites due to environmental concerns about world scale pollution and climatic changes [1-4]. In actuality, natural fibres are regarded as environmentally benign due to their biodegradable and renewable qualities and ability to save energy during processing, which is an inescapable issue for synthetic fibres. Suppose a sufficient amount of fibre is added. In that case, a sufficient amount of fibre is added, and both natural fibres and their composites made of polymers are carbon-neutral regarding the CO2 emissions that result in the earth's greenhouse effect, a key contributor to global warming [5]. In actuality, the content assimilated throughout the growth of the fibre plant will balance off the emission of CO2 caused by combustion or atmospheric decline at the end of the life cycle of these "green" materials.

Natural fibres, in contrast, have significant limitations a component of to some extent, which also impact their polymer composites [1-4].

The performance of composite materials at different temperatures is a crucial consideration when determining which temperature offers the most appropriate material attributes. Because Calotropis Procera can withstand the harsh climate in western Rajasthan, this ability should be expected to translate to its fibre and composite.  The thermal study is the critical factor that affects how the prepared composite turns out. The TGA analysis is the most widely used method for assessing thermal characteristics. The Flynn-Wall technique determined each component and composite material's precise apparent activation energy (Ea). Varying fibre load (5, 10, 15, 20 wt.%) was used to reinforce PF resin, and TGA was taken for all composite samples.

Materials and Methodology

Extraction of Calotropis Procera bast fibre

Calotropois Procera is a desert plant that grows in large quantities in Rajasthan's western region. The corky bark surrounds the steams. Calotropis Procera bark can be used to make strong fibres.

Barks of these plants have been collected from the Bikaner region. These collected barks have been cut into 20-30 cm long pieces and then preserved in water for about 1 week until the barks get smooth. Then natural fibres from these barks are extracted manually. These extracted natural Calotropis Procera (CP) fibres were chopped about 10-15 mm for composite preparation.

Composite preparation

To create the standard PF resin, phenol was first dissolved in formaldehyde (HCHO) in the presence of an alkyl medium (NaOH), and then the mixture was heated at 60 °C while constantly stirred for roughly two hours. The resulting mixture was poured onto a flat, rectangular petri plate and cured at room temperature for three to four days at room temperature to create phenol formaldehyde resin. The procedure for making fibre/polymer composites was the same: chopped fibre was added to the phenol formaldehyde resin (PF) at different loading levels by hand lay-up method. The mixture was then dried in the oven at an even temperature of 60 °C. Prepared composites, then cut into desired shapes and lengths for physical, mechanical and thermal analysis.

Table 1: Sample code according to different fibre load

Fibre load5 wt%10 wt%15 wt%20 wt%
Sample codeU-5U-10U-15U-20

Analysis using TGA

Samples underwent TGA analysis in the PG research lab at IIT Kanpur. This investigation made use of TA Instruments TGA (SDT Q600). The experiments were performed at temperatures as high as 300 °C. The settings were as follows: Heating rates of 5 °C/min, 10°C/min, 15 °C/min, and 20 °C/min from 25 °C to 300°C in a nitrogen environment were used for prepared CP fibre-reinforced PF composite investigation.

Theoretical methods to study chemical kinetics for TGA

TGA experiments are frequently used to forecast the thermal stability of a material. Additional information on the kinetics of heat disintegration and an in-use lifetime can be predicted using a modified experimental setup. By heating the sample steadily, Flynn and Wall's model [6] calculates the breakdown kinetics of breakdown.


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This takes less time than other models that have been suggested for the same goal. This is true for single-step decomposition and first-order kinetics.

The Flynn and Wall model can be applied when the sample is heated gradually and at least three different heating rates are used the sample is heated gradually. The Flynn and Wall model can be applied if at least three different heating rates are used

jcm_06_1.jpg (1)

The numerical value of b is ascertained through an iterative process. The initial b=0.457 is acquired, and equation (1) is then used to calculate the value of Ea. Ea /RT is calculated using this Ea value, where T is the temperature at which constant mass loss occurs. T is the temperature at which the continuous mass loss occurs and is used to calculate Ea /RT. The technique is repeated until Ea stops changing before calculating the value of b corresponding to Ea /RT using Appendix A [7].

Result and Discussion

TGA provides information on weight loss at a specific temperature. The TGA curve for Untreated Aak fibre PF composites is shown in Fig 1 (a-d) with the above heating rates.

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a)

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b)

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c)

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d)

Figure 1 (a-d): TGA curve of untreated Aak fibre PF composite (U-5, U-10, U-1 5 and U-20) with different heat rates.


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The 5% mass loss temperature for all composites is displayed in Table 2. The TGA curve can be used to determine the sample’s thermal stability. The decomposition temperature has risen with increasing fibre content up to 15% fibre weight.

This leads to the conclusion that composites thermal stability significantly increased. The applied heating rate controls the reaction time available at a given temperature. Hence kinetics degradation is directly dependent on the heating rate. The time available for the reaction is typically thought to be longer if the heating rate is lower. A lower temperature with a slower heating rate follows a typical trend in the TGA curve, while it heats up more quickly and decomposes at a higher temperature. In this approach, the heating rate significantly impacts thermal stability.

Table 2: The temperature in ℃ for 5% mass loss at different heating rerates

SampleHeat rate5℃/minHeat rate10℃/minHeat rate15℃/minHeat rate20℃/min
U-5116128135145
U-10139154160168
U-15168181191197
U-20134157163185

A similar observation of thermal degradation of banana-fibre reinforced phenol formaldehyde composite by several researchers [8,9].

Chemical kinetics for TGA

Plotting the multiple TGA curves for all samples in Figure 2 provides an example of this approach. The TGA curve is displayed as coloured lines at various heating rates. Straight black lines represent a constant mass loss. The temperature value for the relevant heating rates can be found at the intersection of the horizontal black lines and the TGA curve. The gradient of this graph is then determined after plotting the line between lnβ and 1000/T. Using the equation below, b=0.457 calculates an approximate value for Ea. Activation energy can be determined by the equation (1).

Now the value of Ea/RT is calculated, here Ea is the value of activation energy obtained by the equation (1), and T is the temperature at a constant mass loss (In this work, chemical kinetics of all samples are measured for 5% constant mass loss with 10 ℃/min heating rate) by this value corresponding value of b can be got by appendix A. We get the new value of Ea. This value of Ea will match the obtained value by eq. (1), which is repeated

until our value of Ea remains unchanged. In the present work, TGA kinetics for all the samples are calculated for only 5% mass loss.

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Figure 2(a-d): log heating rate vs. 1000/T for untreated CP fibre-reinforced PF composite

Table 3: Activation energy of thermal decomposition for untreated CP fibre-reinforced PF composite.

Sample at 5% mass lossb(constant)Ea (KJ/mol)
U-57.440.5281114.59
U-108.850.5281139.3
U-159.800.5187157.07
U-205.210.49188.05

Table 3 shows the chemical kinetics of TGA for all samples. The maximum activation energy is obtained by sample U-15.

Conclusion

TGA was used to study the thermal kinetics of CP fibre-reinforced PF composite. According to TGA U-15, the sample showed better thermal stability than other composites. The value of activation energy for U-15 is 157.07 KJ/mol, the maximum among all composites. The quantity of energy needed to execute a particular transition is referred to as the Ea of any reaction. The higher the Ea value, the more complex the transition. It signifies that the transition took longer since there was more incredible activation energy. A slower transition rate indicates more excellent thermal durability. As a result, the thermal durability of composite increases with increasing fibre loads up to 15wt%.

References

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2. Mohanty, A.K., Misra, M. and Drzal, L.T. (2005) “Natural Fibers, Biopolymers, and Biocomposites”, CRC Press, Taylor & Francis Group, Boca Raton, FL. - References - Scientific Research Publishing. https://www.scirp.org/reference/ReferencesPapers.aspx?ReferenceID=1867231 (accessed Oct. 06, 2022).

3. Mohanty, A.K., Misra, M. and Hinrichsen, G. (2000) “Biofibres, biodegradable polymers and bio-composites an overview”. Macromolecular Materials and Engineering, 1, 276-277.

4. A. K. Mohanty, L. T. Drzal and M. Misra, “Engineered Natural Fiber Reinforced Polypropylene Composites Influence of Surface Modifications and Novel Powder Impregnation Processing”, Journal of Adhesion Science and Technology, Vol. 16, 2002, p. 999. - References - Scientific Research Publishing.” https://www.scirp.org/reference/ReferencesPapers.aspx?ReferenceID=74954 (accessed Oct. 06, 2022).

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6. J. H. Flynn and L. A. Wall, “A quick, direct method for the determination of activation energy from thermogravimetric data,” J Polym Sci B, vol. 4, no. 5, pp. 323–328, May 1966, doi: 10.1002/POL.1966.110040504.

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8. S. Joseph, K. Joseph, and S. Thomas, “Green composites from natural rubber and oil palm fiber: Physical and mechanical properties,” International Journal of Polymeric Materials and Polymeric Biomaterials, vol. 55, no. 11, pp. 925–945, Nov. 2006, doi: 10.1080/00914030600550505.

9. P. V. Joseph, M. S. Rabello, L. H. C. Mattoso, K. Joseph, and S. Thomas, “Environmental effects on the degradation behaviour of sisal fibre reinforced polypropylene composites,” Compos Sci Technol, vol. 62, no. 10–11, pp. 1357–1372, Aug. 2002, doi: 10.1016/S0266-3538(02)00080-5.


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