1. INTRODUCTION
The carbon products obtained from industrial sources has been used as filler in various polymers [
1,
2,
3]. It has been extensively practiced in industrial sectors to advance the routine properties of polymeric products [
4,
5,
6]. There has been a dynamic study in industrial and academic fields to study composites and nanocomposites of polymers. Polymeric composites have proven as a major and unremarkable endeavor. The major technical and commercial interest lies in the ubiquitous existence of properties in consumer products. Usually, the polymers modified with carbon products have been investigated for their thermal, conductive, thermoelectric, tensile, mechanical, corrosion, and erosive properties [
7,
8,
9,
10].
The production of biochar (BC) from agricultural waste is the leading and cheapest source for the production of nanocarbon as an industrial product with a predicted yearly production of fifteen metric tons by 2025 [
11]. BC is fundamentally produced from the carbonization of carbon resources such as biomass, fossil fuels, and biofuels [
12]. Thus, to achieve large-scale productivity, low-cost raw material, and inexpensive products with required properties, BC can be seen to be an appealing choice [
13,
14].
It is a known fact that carbon-based materials like carbon black, chars, or activated carbon have demonstrated fine pore size development than wood-based carbon products. The majority of the pore volume has shown a radius of < 1 nm in the case of coconut shells, while carbon material originating from wood has a significant number of macropores and mesopores [
15,
16]. A survey was performed on various agricultural by-products like almond shells and seeds of peach, grape, cherry, apricot, and palm with the conclusion that the botanical origin of the family of the selected material also affects the distribution of pore size [
17,
18]. BC specifically obtained from coconut shells as a bio-carbon source has the potential for substituting the conventional thermoset filler in wear applications due to their high strength, low density, hardness, abrasion resistance, and modulus properties [
19,
20].
The tailoring in inbuilt characteristics and achievement of required characters of a matrix is usually accomplished by using fillers poly(1,4-phenylene sulfide) (PPS) is the most extensively utilized semicrystalline polymer. It retains superior thermal, chemical, mechanical, antiaging, flame resistant, water resistant, low thermal expansion coefficient, and exceptional friction properties [
21,
22]. Surface protection is one of the major requirements of industries using high-temperature conditions. The PPS has been successfully employed as a protective coating because of superior melt temperature, good chemicals, and excellent abrasive resistance. PPS is a high-performance thermoplastic so its high-performance thermoplastic composites are taking a progressively significant role in thermoplastic applications. The benefits include the properties such as elevated impact resistance, toughness, better chemical and corrosion endurance, easy processing, indefinite shelf lifespan of the prepregs, and the ability to get recycled [
23,
24].
In the category of carbon-based composites of PPS investigation has been carried out using glass fiber (GF), carbon fiber (CF), metal oxides, graphene, Mxene, short carbon fibers (SCFs), nanodiamonds (NDs), and graphene oxide (GO). Systematic evaluation of behavioral isothermal and non-isothermal crystallization of PPS modified with short glass fiber has been done by different models. Detail is available on the crystallization evolution, dynamic mechanical properties, along with aging effects using heat treatment [
25]. The PPS and CF-reinforced composites have been investigated for thermomechanical, fracture resistance, and tribological properties [
26]. Short carbon fibers graphene oxide, and nanodiamonds (NDs) based composites of PPS have been reported for their ability to be utilized in membranes, friction reduction, and wear applications [
27]. Its conductive polymer composites have been discovered as feasible replacements for electrolytic membranes of fuel cells and bipolar plates [
28].
Research findings on the use of activated nanocarbon in various material manufacturing are still on way because of its ability in renewable energy harvesting [
29,
30], and environmental applications especially focusing on global challenges on clean energy, sensors [
31], dielectric and EMI applications [
32], high-performance batteries [
33], electrochemical energy storage, and environmental remediation [
34,
35]. The addition of BC to elastomeric materials has been studied in many industrial applications [
36,
37]. In current research seeing the easy tailorability and modifiable properties of PPS for many useful applications, its undiscovered biochar-based composites (PPS@BC) were synthesized. BC was synthesized from raw coconut shells. As a high-performance engineering polymer thermal and crystallization properties of PPS are shown to be affected by the percentage of blending, technique of synthesis, and nature of reinforcement [
29,
38].
Herein study was conducted to explore the thermal, morphological, and crystalline properties of the PPS@BC composites. Composites were made using the coagulation protocol. The investigation was done by loading different percentages of synthesized BC to the PPS matrix and variation in properties was studied.
Figure 1.
Schematic flow of the experimental workup.
Figure 1.
Schematic flow of the experimental workup.
Figure 2.
FESEM overview of BC at different magnifications.
Figure 2.
FESEM overview of BC at different magnifications.
Figure 3.
BSE image of BC.
Figure 3.
BSE image of BC.
Figure 4.
Isotherm linear plots and size distribution analysis of BC at STP.
Figure 4.
Isotherm linear plots and size distribution analysis of BC at STP.
Figure 5.
XRD spectral pattern of BC.
Figure 5.
XRD spectral pattern of BC.
Figure 6.
FTIR spectra of PPS@BC nanocomposites.
Figure 6.
FTIR spectra of PPS@BC nanocomposites.
Figure 7.
TGA curves of PPS@BC nanocomposites.
Figure 7.
TGA curves of PPS@BC nanocomposites.
Figure 8.
Comparative analysis T5, T10, and T50 PPS@BC nanocomposites.
Figure 8.
Comparative analysis T5, T10, and T50 PPS@BC nanocomposites.
Figure 9.
DSC curves of PPS@BC nanocomposites (a) cooling cycle (b) heating cycle.
Figure 9.
DSC curves of PPS@BC nanocomposites (a) cooling cycle (b) heating cycle.
Figure 10.
Comparative illustration of Tc and Tm of PPS@BC nanocomposites.
Figure 10.
Comparative illustration of Tc and Tm of PPS@BC nanocomposites.
Figure 11.
Graphic illustration of the change in the degree of supercooling of PPS@BC nanocomposites.
Figure 11.
Graphic illustration of the change in the degree of supercooling of PPS@BC nanocomposites.
Figure 12.
Glass transition analysis of PPS@BC nanocomposites.
Figure 12.
Glass transition analysis of PPS@BC nanocomposites.
Figure 13.
Comparison of the degree of crystallinity and glass transition temperature of PPS@BC nanocomposites.
Figure 13.
Comparison of the degree of crystallinity and glass transition temperature of PPS@BC nanocomposites.
Figure 13.
FESEM images of samples (a) PPS at 5 µm (b) PPS-2 at 5 µm (c) PPS-4 at 5 µm (d) PPS-6 at 5 µm (e) PPS-8 at 5 µm (f) PPS-10 at 5 µm (g) PPS at 500 nm (h) PPS-2 at 500 nm (i) PPS-4 at 500 nm (j) PPS-6 at 500 nm (k) PPS-8 at 500 nm (l) PPS-10 at 500 nm.
Figure 13.
FESEM images of samples (a) PPS at 5 µm (b) PPS-2 at 5 µm (c) PPS-4 at 5 µm (d) PPS-6 at 5 µm (e) PPS-8 at 5 µm (f) PPS-10 at 5 µm (g) PPS at 500 nm (h) PPS-2 at 500 nm (i) PPS-4 at 500 nm (j) PPS-6 at 500 nm (k) PPS-8 at 500 nm (l) PPS-10 at 500 nm.
Figure 14.
BSE images of PPS@ BC nanocomposites (a) PPS, (b) BSE PPS-2, (c) PPS-4, (d) PPS-6, (e) PPS-8, (f) PPS-10.
Figure 14.
BSE images of PPS@ BC nanocomposites (a) PPS, (b) BSE PPS-2, (c) PPS-4, (d) PPS-6, (e) PPS-8, (f) PPS-10.
Figure 15.
Quantitative analysis results of weight fraction of carbon from EDS.
Figure 15.
Quantitative analysis results of weight fraction of carbon from EDS.
Table 1.
EDS composition of BC.
Table 1.
EDS composition of BC.
Sample |
Carbon (wt %) |
Oxygen (wt %) |
Potassium (wt %) |
BC |
90.2 |
9.5 |
0.3 |
Table 2.
SAP parameters of BC.
Table 2.
SAP parameters of BC.
Sample |
Specific surface area (SBET) |
Langmuir surface area (SL) |
|
Average pore diameter (D) |
BC |
1517 m²/g |
2175 m²/g |
|
2.51 nm |
Table 3.
Peak position (°) of BC on the 2θ scale determined from the XRD pattern.
Table 3.
Peak position (°) of BC on the 2θ scale determined from the XRD pattern.
Sample |
Plane (002) |
Plane (10) |
BC |
28.4 |
40.7 |
Table 4.
Structural information of BC determined from XRD patterns.
Table 4.
Structural information of BC determined from XRD patterns.
Sample |
d002 (Å) |
FWHM |
Lc (nm) |
La (nm) |
N (Items) |
δ (nm-2) |
ε (x 10 -3) |
ρ (g/cm3) |
Crystallinity Index (%) |
BC |
3.140 |
0.195 |
42.024 |
90.585 |
13.383 |
0.566 |
3.362 |
0.243 |
53.077 |
Table 5.
FTIR data of PPS@BC nanocomposites.
Table 5.
FTIR data of PPS@BC nanocomposites.
Samples |
Wavenumber (cm-1) |
O-H (stret) |
C-H (stret) |
Benz ring (sym stretch) |
Benz ring (asym stret)
|
C-S (aliph stret)
|
C-H (out of plane) |
Benz ring (sym ring-S stretch) |
PPS |
- |
2373 (w) |
1454 (s) |
1382 (w) |
1087 (w) |
807 (m) |
476 (m) |
PPS-2 |
3433 (w) |
2333 (w) |
1647 |
1462 (w) |
1082 (w) |
811 (m) |
469 (m) |
PPS-4 |
3433 (s) |
2365 (w) |
1652 (s) |
1468 (w) |
1087 (w) |
817 (m) |
475 (m) |
PPS-6 |
3433 (s) |
2341 (w) |
1657 (s) |
1468 (w) |
1089 (w) |
817 (m) |
480 (m) |
PPS-8 |
3433 (s) |
2398 (w) |
1657 (s) |
1468 (w) |
1089 (w) |
811 (m) |
478 (m) |
PPS-10 |
3433 (s) |
2364 (w) |
1652 (s) |
1468 (w) |
1084 (w) |
811 (m) |
475 (m) |
aliph= aliphatic, stret = stretching, sym= symmetric, asym= asymmetric, Benz = Benzene, w = Weak, s = Sharp, m = Medium |
Table 6.
TGA data of PPS@BC nanocomposites.
Table 6.
TGA data of PPS@BC nanocomposites.
Compounds |
T5 (oC ) |
T10 (oC ) |
T50 (oC ) |
Tf (oC ) |
Rf (%) |
PPS |
90 |
127 |
567 |
646 |
45 |
PPS-2 |
118 |
187 |
573 |
654 |
46 |
PPS-4 |
123 |
188 |
579 |
656 |
46 |
PPS-6 |
157 |
250 |
580 |
659 |
46 |
PPS-8 |
66 |
100 |
545 |
645 |
39 |
PPS-10 |
56 |
76 |
521 |
606 |
34 |
Table 7.
Data obtained from DSC trace of PPS@BC nanocomposites.
Table 7.
Data obtained from DSC trace of PPS@BC nanocomposites.
Compounds |
Toc (°C) |
Tc (°C) |
∆Hc (J/g) |
Tom (°C) |
Tm (°C) |
∆Hm (J/g) |
∆T (°C) |
Xc (%) |
Tg (°C) |
PPS |
252.1 |
242.5 |
45.2 |
261.7 |
281.8 |
35.9 |
38.5 |
40.4 |
134.7 |
PPS-2 |
265.2 |
257.4 |
41.6 |
271.6 |
284.8 |
29.2 |
27.4 |
37.89 |
129.6 |
PPS-4 |
264.8 |
256.9 |
35.8 |
263.4 |
284.5 |
28.6 |
27.5 |
34.7 |
119.4 |
PPS-6 |
269.5 |
258.3 |
36.0 |
274.5 |
284.8 |
12.0 |
26.5 |
33.5 |
117.5 |
PPS-8 |
268.4 |
255.1 |
25.7 |
265.6 |
283.9 |
28.6 |
28.8 |
24.4 |
135.4 |
PPS-10 |
269.5 |
253.2 |
22.7 |
268.8 |
283.9 |
16.7 |
30.6 |
22.5 |
149.8 |