This section presents the surface chemistry analysis of the developed ceiling materials. Compounds that are likely to be emitted during the performance and combustion processes were identified along with compounds with binding capability and possible noxious characteristics. For an easy identification and discussion, the samples have been coded A1, A2, A3 and A4 in place of 0.6Aldr0.3Cmt0.05G0.05OBS,0.6Aldr0.34Cmt0.05G0.01OBS,0.6Aldr0.32Cmt0.05G0.03UES, and 0.3Aldr0.23Cmt0.3Si0.05G0.12CS. Aldr is Aluminium dross, Cmt is Cement, Si is Silicate, G is Carbon Graphite, OBS is Oil Bean Stalk, UES is Uncarbonized Egg Shell, and CS is Coconut Shell. Figure 3 to Fig. 6 show the biophase and triphase quantification of developed ceiling composite samples and their peak at a different diffracted angle.
Eight phases were evidenced by the qualitative XRD pattern at Braga angles of 18.60, 23.20, 29.50, 37.80, 43.40, 48.60, 57.60, and 60.80 as shown in Fig. 3. The constitutive materials for A1 are aluminium dross 60%, cement 30%, carbon graphite 5% and oil beanstalk 5%. The materials had inherent elements that could likely cause diffraction when bombarded by an X-ray.
The substances present were silicon oxide, calcio-olivine, cordierite ferroan, kyanite, and dialuminum silicate oxide. It confirms that it is a heterogeneous material with aluminium and cement having dominance. The material is crystal in nature with the lattice structure of body-centred cubic (BCC), face-centred cubic (FCC), and hexagonal cubic packing (HCP) arrangements, mainly present. The crystalline nature is characteristic of cement, which is partly present in this composite [18]. The grain size of the materials is 0.234 nm. The presence of elements such as magnesium, aluminium, silicon, and calcium make the compound overall non-flammable at the instance of combustion, as revealed by earlier workers [19, 20]. Oxygen contributes to negligible weight loss when subjected to burning. Its minimal concentration is significant to flame spread inhibition [21, 22]. Mg2(Al4Si5O18) is also called Cordierite, or ferroan, which is substantial at peak 1 as shown in Fig. 3.
At phase 2, the substances present were calico-olivine, cordierite ferroan, dicalcium diiron (III) oxide, kyanite, and dialuminum silicate oxide. Ca2Fe2O5 is significant as it is deposited at this peak. Calcium olivine is a natural mineral, an orthosilicate type that is usually found at the earth subsurface. It is orthorhombic in its crystal system [23]. Its melting temperature is unusually high ≈ 2000 oC [24] with a high covalent bond [25]. This makes it a contributory flame retardant compound. Dialuminium silicate is a naturally occurring soil constituent, usually called clay that is composed of trace metal oxide and anhydrous aluminium silicate. The constituent element that forms the compound reveals it is partly covalent and partly ionic, according to earlier reports [26]. The bond of these elements forms a barrier for oxygen to diffuse, thus raising the thermal effusivity and flame retardant characteristics of the developed composite ceiling materials. The minuscule weight loss was due to the flammable additive in the composite [27]. Kyanite is a polymorph that is triclinic in the crystal system and crystal bladed or tabular in morphology [28]. Two aluminium atoms suggest that one is more ionically bonded in one and covalently bonded in the other [29]. Silicone is present in the compound, which is a flame retardant indicator.
A closer look at peak 3 revealed that the substances present were silicon oxide, calcium olivine and cordierite ferroan. However, Ca2(SiO4) called Calcio-olivine is deposited, as shown in Fig. 3. The bond interaction of silicon inhibits the thermal conductivity nature of the metallic element, such as Al and Mg and flame fuel nature of oxygen, which is present in most of the compounds [27]. Once oxygen is suppressed, there isn’t room for successful combustion, which is a desirable result in ceiling composites. At peak 4, the elements present are corundum, calico-olivine, cordierite ferroan, dicalcium diiron (III) oxide, kyanite, and dialuminum silicate oxide. However, Al2(SiO4)O was placed at this peak. The absence of carbon as present in the preliminary materials such as aluminium dross, cement, oil bean husk, and carbon graphite were probably due to its deficient composition and low energy when zapped with a beam of X-ray.
At peak three-phase, substances present at this peak were corundum, cordierite ferroan, and dicalcium diiron (III) oxide. Al2O3 called corundum was deposited at this peak. The average interplanar spacing Fig...is 0.49nm. Investigating XRD Analysis of A2,0.6Aldr0.34Cmt0.05G0.01OBS, the peak where the compounds are deposited is represented in numbers in Fig. 4, which shows the presence of binding elements and compounds that are flame retardant in composition. Also, for XRD Analysis of A3,0.6Aldr0.32Cmt0.05G0.03UES, the peak where the compounds were deposited is represented in Fig. 5. The compounds exhibited flame retardance and an absence of harmful substances as evidenced in the emission behaviour following its combustion. During the XRD analysis of A4,0.3Aldr0.23Cmt0.3Si0.05G0.12CS, the peak where the substances were deposited is represented in numbers in Fig. 6. The elements calcium and magnesium (alkaline earth metals), and aluminium are not flammable at the operating temperature. Their presence is also evidence of the excellent bond of the composite. The presence of silicon also provides a shield from flame penetration, which in the overall will retard a significantly flame spread.
3.1 Concentration of Gas Emission and Temperature of Emission @ 0.01kg for all Samples
3.1.1 A1: 0.6Aldr0.3Cmt0.05G0.05OBS
Tables 1–4 present the emission characteristics of selected samples A1-A4 which give the values of the noxious elements emitted in part per million (ppm). The emission detection or non-detection of noxious substances is in conformity to international standards and would help to determine the suitability or not of the developed composite materials for ceiling purposes.
From Table 1 at a preset temperature of 500oC in the muffler furnace, it took 24 minutes to reach maximum temperature. Effervescence evolved at 12 minutes for CO2 and 11 minutes for NO. The highest CO value (2265 ppm) occurred at time 19 seconds at temperature of 456oC. At this the point, the value of CO2 was constant at 0.5 ppm, and O2 was also steady at 19.8 ppm. Reduction in O2 at 19.8 ppm at time (18–24) minutes enabled CO2 to be maximum and constant at this range while there was a significant uptrend in the values of NO/NOx which came to a peak at 49 ppm. A completely enclosed apartment during a fire outbreak will reduce the O2 level, causing the significant rise and diffusion of CO2 and nitrogen compounds. The gas SO2 was not detected at any point during the period of burning. This observation was particularly connected to the elemental nature of the understudied ceiling composite sample A1. The values of the noxious nitrogen gas increased as the temperature and time increased, indicating that its diffusion was temperature-dependent.
3.1.2 A2: 0.6Aldr0.34Cmt0.05G0.01OBS
From Table 2, the temperature value of 5000C was reached at 37 minutes, while 3000C was the temperature to start up the momentum of CO gas at 54 ppm. The reluctance up to this point is connected to the bond force of the atomic structure of the ceiling composite. However, SO2 is detected at a maximum of 3 ppm and discontinued when CO started. SO2 presence is linked to visible flame rich in O2 and in absence of CO. Maximum values of NO/NOx were observed at maximum temperature, minimum O2 and maximum CO2.
3.1.3 A3: 0.6Aldr0.32Cmt0.05G0.03UES
From Table 3, 45 minutes elapsed before a temperature of 500oC was attained. Nitrogen compounds at 2 ppm and 295oC were not detected until 25 minutes. At this temperature, the charring of modern protective clothing fabrics begins [30].CO2level was generally low at 0.1 ppm, which is desirable. CO maximum, 1281 ppm, was reached at 42 minutes and experienced a stable rise with temperature. Maximum NO/NOx was 46 ppm at maximum temperature. This observation was expected and well confirmed by earlier workers [31] that nitrogen oxide increases at an increasing temperature.
3.1.4 A4: 0.3Aldr0.23Cmt0.3Si0.05G0.12CS
From developed0.3Aldr0.23cmt0.3Si0.05G0.12CS, it took 37 minutes to attain the preset temperature of 5000C, as shown in Table 4. The inherent thermal inertia was probably responsible for the reluctance in heat dissipation as evidenced by the long-time extension compared to that of A1. The variation in material percentage mixture is also a causative feature. The peak value of CO at 5236 ppm came to fore at 19 minutes. At this point, concentration mass transfer of CO was maximum and undulated before and after this value due to collision with other molecules and ripple temperature. The nitrogen compound was at zero levels up to 16 minutes. The reason might be due to the source of combustion and the probable presence of nitrogen and oxygen in the elemental buildup of this ceiling composite. Values of NO/NOx increased due to a corresponding temperature rise. It came to a maximum at 38 ppm at maximum temperature of 5000C. Maximum O2 at 21.0 ppm established null CO2 (0.0 ppm). The presence of CO reduces the survival chances of occupants due to the low oxygen level. Low O2 permits emission of other noxious gases such as NO/NOx, CO2, which contributes to discomfort at the fire outbreak. Emission especially has drastically reduced, and air quality has improved over the last four decades due to close monitoring by international bodies such as World Health Organizations (WHO) and European Union (EU) as confirmed by previous studies [32].
Table 1: A1, 0.6Aldr0.3Cmt0.05G0.05OBS
Time (min)
|
Tg(OC)
|
Temp. (oC)
|
CO (ppm)
|
O2(ppm)
|
CO2(ppm)
|
NO(ppm)
|
NOX(ppm)
|
NO2(ppm)
|
SO2(ppm)
|
1
|
53
|
233
|
33
|
20.8
|
0
|
0
|
0
|
0
|
0
|
2
|
92
|
273
|
37
|
20.8
|
0
|
0
|
0
|
0
|
0
|
3
|
128
|
287
|
40
|
20.8
|
0
|
0
|
0
|
0
|
0
|
4
|
142
|
294
|
41
|
20.8
|
0
|
0
|
0
|
0
|
0
|
5
|
170
|
305
|
46
|
20.8
|
0
|
0
|
0
|
0
|
0
|
6
|
201
|
317
|
59
|
20.7
|
0
|
0
|
0
|
0
|
0
|
7
|
236
|
331
|
87
|
20.7
|
0
|
0
|
0
|
0
|
0
|
8
|
258
|
341
|
178
|
20.6
|
0
|
0
|
0
|
0
|
0
|
9
|
282
|
352
|
324
|
20.5
|
0
|
0
|
0
|
0
|
0
|
10
|
305
|
363
|
603
|
20.5
|
0
|
0
|
0
|
0
|
0
|
11
|
329
|
373
|
877
|
20.4
|
0
|
3
|
3
|
0
|
0
|
12
|
356
|
386
|
1211
|
20.3
|
0.2
|
3
|
3
|
0
|
0
|
13
|
374
|
395
|
1213
|
20.4
|
0.2
|
3
|
3
|
0
|
0
|
14
|
391
|
406
|
1333
|
20.3
|
0.2
|
4
|
4
|
0
|
0
|
15
|
407
|
416
|
1458
|
20.2
|
0.3
|
4
|
4
|
0
|
0
|
16
|
423
|
427
|
1798
|
20.0
|
0.4
|
6
|
6
|
0
|
0
|
17
|
437
|
436
|
1201
|
19.9
|
0.4
|
7
|
7
|
0
|
0
|
18
|
453
|
446
|
1217
|
19.8
|
0.5
|
10
|
10
|
0
|
0
|
19
|
465
|
456
|
2265
|
19.8
|
0.5
|
13
|
13
|
0
|
0
|
20
|
479
|
465
|
2212
|
19.8
|
0.5
|
16
|
16
|
0
|
0
|
21
|
494
|
477
|
2120
|
19.8
|
0.5
|
23
|
23
|
0
|
0
|
22
|
503
|
484
|
2054
|
19.8
|
0.5
|
30
|
30
|
0
|
0
|
23
|
515
|
494
|
1951
|
19.8
|
0.5
|
40
|
40
|
0
|
0
|
24
|
527
|
500
|
1828
|
19.8
|
0.5
|
49
|
49
|
0
|
0
|
Table 2: A2,0.6Aldr0.34Cmt0.05G0.01OBS
Time (min)
|
Temp. (oC)
|
Tg (oC)
|
CO (ppm)
|
O2(ppm)
|
CO2(ppm)
|
NO(ppm)
|
NOX(ppm)
|
NO2(ppm)
|
SO2(ppm)
|
1
|
103
|
47
|
0
|
20.7
|
0.3
|
0
|
0
|
0
|
3
|
2
|
130
|
55
|
0
|
20.7
|
0.3
|
0
|
0
|
0
|
3
|
3
|
143
|
67
|
0
|
20.6
|
0.2
|
0
|
0
|
0
|
3
|
4
|
155
|
79
|
0
|
20.7
|
0.2
|
0
|
0
|
0
|
3
|
5
|
167
|
91
|
0
|
20.7
|
0.2
|
0
|
0
|
0
|
3
|
6
|
179
|
104
|
0
|
20.6
|
0.3
|
0
|
0
|
0
|
3
|
7
|
190
|
117
|
0
|
20.7
|
0.2
|
0
|
0
|
0
|
2
|
8
|
201
|
129
|
0
|
20.7
|
0.2
|
0
|
0
|
0
|
3
|
9
|
212
|
144
|
0
|
20.7
|
0.2
|
0
|
0
|
0
|
3
|
10
|
224
|
160
|
0
|
20.7
|
0.2
|
0
|
0
|
0
|
2
|
11
|
235
|
176
|
0
|
20.7
|
0.2
|
0
|
0
|
0
|
2
|
12
|
246
|
192
|
0
|
20.7
|
0.3
|
0
|
0
|
0
|
2
|
13
|
258
|
209
|
0
|
20.7
|
0.3
|
0
|
0
|
0
|
2
|
14
|
269
|
224
|
0
|
20.7
|
0.3
|
0
|
0
|
0
|
2
|
15
|
279
|
240
|
0
|
20.6
|
0.3
|
0
|
0
|
0
|
2
|
16
|
290
|
256
|
0
|
20.6
|
0.3
|
0
|
0
|
0
|
2
|
17
|
300
|
270
|
54
|
20.5
|
0.3
|
2
|
2
|
0
|
0
|
18
|
312
|
283
|
191
|
20.5
|
0.5
|
2
|
2
|
0
|
0
|
19
|
322
|
297
|
348
|
20.4
|
0.5
|
3
|
3
|
0
|
0
|
20
|
333
|
313
|
558
|
20.4
|
0.6
|
4
|
4
|
0
|
0
|
21
|
344
|
329
|
809
|
20.3
|
0.6
|
5
|
5
|
0
|
0
|
22
|
354
|
345
|
1056
|
20.3
|
0.8
|
6
|
6
|
0
|
0
|
23
|
364
|
360
|
1196
|
20.2
|
0.8
|
6
|
6
|
0
|
0
|
24
|
374
|
374
|
1320
|
20.2
|
0.9
|
6
|
6
|
0
|
0
|
25
|
384
|
386
|
1305
|
20.1
|
0.9
|
5
|
5
|
0
|
0
|
26
|
395
|
399
|
1250
|
20.1
|
0.8
|
5
|
5
|
0
|
0
|
27
|
405
|
412
|
1236
|
20.1
|
1.0
|
5
|
5
|
0
|
0
|
28
|
415
|
424
|
1308
|
20.0
|
1.0
|
5
|
5
|
0
|
0
|
29
|
425
|
437
|
1423
|
19.9
|
1.2
|
6
|
6
|
0
|
0
|
30
|
435
|
450
|
1525
|
19.8
|
1.3
|
8
|
8
|
0
|
0
|
31
|
445
|
462
|
1564
|
19.7
|
1.4
|
10
|
10
|
0
|
0
|
32
|
454
|
476
|
1616
|
19.7
|
1.4
|
13
|
13
|
0
|
0
|
33
|
464
|
489
|
1699
|
19.7
|
1.5
|
16
|
16
|
0
|
0
|
34
|
473
|
501
|
1740
|
19.7
|
1.5
|
20
|
20
|
0
|
0
|
35
|
483
|
511
|
1712
|
19.7
|
1.5
|
27
|
27
|
0
|
0
|
36
|
492
|
521
|
1608
|
19.7
|
1.4
|
34
|
34
|
0
|
0
|
37
|
500
|
533
|
1444
|
19.8
|
1.4
|
44
|
44
|
0
|
0
|
Table 3: A3, 0.6Aldr0.32Cmt0.05G0.03UES
Time (min)
|
Temp. (oC)
|
Tg (oC)
|
CO (ppm)
|
O2(ppm)
|
CO2(ppm)
|
NO(ppm)
|
NOX(ppm)
|
NO2(ppm)
|
SO2(ppm)
|
1
|
34
|
25
|
10
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
2
|
36
|
26
|
12
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
3
|
44
|
28
|
15
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
4
|
53
|
31
|
17
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
5
|
63
|
36
|
20
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
6
|
74
|
43
|
21
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
7
|
85
|
51
|
22
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
8
|
97
|
60
|
24
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
9
|
108
|
70
|
27
|
20.8
|
0.2
|
0
|
0
|
0
|
0
|
10
|
120
|
80
|
27
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
11
|
132
|
92
|
31
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
12
|
144
|
104
|
29
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
13
|
156
|
117
|
32
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
14
|
168
|
129
|
33
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
15
|
180
|
142
|
34
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
16
|
192
|
156
|
35
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
17
|
204
|
170
|
36
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
18
|
215
|
184
|
36
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
19
|
226
|
198
|
42
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
20
|
237
|
213
|
42
|
20.7
|
0.1
|
0
|
0
|
0
|
0
|
21
|
249
|
229
|
53
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
22
|
260
|
243
|
73
|
20.8
|
0.1
|
0
|
0
|
0
|
0
|
23
|
272
|
258
|
103
|
20.7
|
0.2
|
0
|
0
|
0
|
0
|
24
|
284
|
272
|
144
|
20.7
|
0.2
|
0
|
0
|
0
|
0
|
25
|
295
|
286
|
212
|
20.7
|
0.2
|
2
|
2
|
0
|
0
|
26
|
306
|
299
|
313
|
20.7
|
0.3
|
2
|
2
|
0
|
0
|
27
|
316
|
313
|
494
|
20.6
|
0.4
|
3
|
3
|
0
|
0
|
28
|
327
|
327
|
645
|
20.5
|
0.4
|
4
|
4
|
0
|
0
|
29
|
338
|
342
|
856
|
20.4
|
0.5
|
4
|
4
|
0
|
0
|
30
|
349
|
358
|
990
|
20.4
|
0.5
|
4
|
4
|
0
|
0
|
31
|
359
|
371
|
1113
|
20.3
|
0.6
|
3
|
3
|
0
|
0
|
32
|
369
|
382
|
1219
|
20.3
|
0.7
|
4
|
4
|
0
|
0
|
33
|
380
|
393
|
1056
|
20.4
|
0.7
|
3
|
3
|
0
|
0
|
34
|
390
|
405
|
1039
|
20.3
|
0.7
|
4
|
4
|
0
|
0
|
35
|
401
|
416
|
1062
|
20.3
|
0.7
|
5
|
5
|
0
|
0
|
36
|
411
|
427
|
1113
|
20.2
|
0.8
|
6
|
6
|
0
|
0
|
37
|
421
|
439
|
1158
|
20.1
|
0.9
|
8
|
8
|
0
|
0
|
38
|
431
|
450
|
1187
|
20.0
|
1.0
|
10
|
10
|
0
|
0
|
39
|
441
|
462
|
1207
|
20.0
|
1.1
|
13
|
13
|
0
|
0
|
40
|
451
|
474
|
1232
|
20.0
|
1.1
|
16
|
16
|
0
|
0
|
41
|
461
|
485
|
1267
|
20.0
|
1.0
|
20
|
20
|
0
|
0
|
42
|
471
|
496
|
1281
|
20.0
|
1.0
|
24
|
24
|
0
|
0
|
43
|
480
|
505
|
1249
|
20.0
|
1.0
|
30
|
30
|
0
|
0
|
44
|
489
|
514
|
1174
|
20.0
|
1.0
|
38
|
38
|
0
|
0
|
45
|
500
|
524
|
1076
|
20.0
|
1.0
|
46
|
46
|
0
|
0
|
Table 4: A4, 0.3Aldr0.23Cmt0.3Si0.05G0.12CS
Time (min)
|
Temp. (oC)
|
Tg (oC)
|
CO (ppm)
|
O2(ppm)
|
CO2(ppm)
|
NO(ppm)
|
NOX(ppm)
|
NO2(ppm)
|
SO2(ppm)
|
1
|
103
|
35
|
0
|
21.0
|
0
|
0
|
0
|
0
|
0
|
2
|
134
|
49
|
0
|
21.0
|
0
|
0
|
0
|
0
|
0
|
3
|
148
|
64
|
0
|
21.0
|
0
|
0
|
0
|
0
|
0
|
4
|
160
|
77
|
0
|
21.0
|
0
|
0
|
0
|
0
|
0
|
5
|
172
|
89
|
0
|
21.0
|
0
|
0
|
0
|
0
|
0
|
6
|
183
|
101
|
0
|
20.9
|
0
|
0
|
0
|
0
|
0
|
7
|
194
|
114
|
0
|
21.0
|
0
|
0
|
0
|
0
|
0
|
8
|
206
|
128
|
0
|
20.9
|
0
|
0
|
0
|
0
|
0
|
9
|
217
|
144
|
0
|
20.9
|
0
|
0
|
0
|
0
|
0
|
10
|
229
|
160
|
4
|
20.9
|
0
|
0
|
0
|
0
|
0
|
11
|
241
|
179
|
12
|
20.9
|
0
|
0
|
0
|
0
|
0
|
12
|
252
|
195
|
42
|
20.9
|
0
|
0
|
0
|
0
|
0
|
13
|
263
|
213
|
144
|
20.9
|
0
|
0
|
0
|
0
|
0
|
14
|
275
|
232
|
366
|
20.9
|
0
|
0
|
0
|
0
|
0
|
15
|
285
|
251
|
744
|
20.7
|
0.3
|
0
|
0
|
0
|
0
|
16
|
296
|
270
|
1412
|
20.5
|
0.5
|
2
|
2
|
0
|
0
|
17
|
307
|
290
|
2524
|
20.2
|
0.9
|
6
|
6
|
0
|
0
|
18
|
318
|
310
|
4304
|
20.0
|
1.1
|
16
|
16
|
0
|
0
|
19
|
329
|
331
|
5236
|
20.0
|
1.0
|
34
|
34
|
0
|
0
|
20
|
339
|
350
|
4163
|
20.3
|
0.6
|
42
|
42
|
0
|
0
|
21
|
349
|
367
|
3541
|
20.4
|
0.5
|
35
|
35
|
0
|
0
|
22
|
360
|
382
|
3857
|
20.4
|
0.5
|
30
|
30
|
0
|
0
|
23
|
371
|
393
|
3885
|
20.4
|
0.5
|
25
|
25
|
0
|
0
|
24
|
381
|
406
|
3819
|
20.4
|
0.5
|
20
|
20
|
0
|
0
|
25
|
391
|
419
|
3624
|
20.4
|
0.6
|
17
|
17
|
0
|
0
|
26
|
402
|
431
|
3402
|
20.4
|
0.6
|
15
|
15
|
0
|
0
|
27
|
412
|
443
|
3229
|
20.4
|
0.6
|
14
|
14
|
0
|
0
|
28
|
422
|
455
|
3055
|
20.3
|
0.6
|
14
|
14
|
0
|
0
|
29
|
432
|
464
|
2878
|
20.3
|
0.7
|
15
|
15
|
0
|
0
|
30
|
442
|
476
|
2720
|
20.3
|
0.6
|
16
|
16
|
0
|
0
|
31
|
452
|
486
|
2591
|
20.3
|
0.7
|
19
|
19
|
0
|
0
|
32
|
461
|
496
|
2477
|
20.3
|
0.7
|
23
|
23
|
0
|
0
|
33
|
470
|
505
|
2396
|
20.3
|
0.7
|
27
|
27
|
0
|
0
|
34
|
480
|
514
|
2369
|
20.2
|
0.8
|
31
|
31
|
0
|
0
|
35
|
490
|
523
|
2333
|
20.2
|
0.7
|
33
|
33
|
0
|
0
|
36
|
498
|
534
|
2310
|
20.3
|
0.7
|
37
|
37
|
0
|
0
|
37
|
500
|
537
|
2313
|
20.3
|
0.7
|
38
|
38
|
0
|
0
|
The cooling rate during the combustion-emission experiment was obtained from the cooling gradient to time. The cooling gradient is shown in Figs. 7–10. The comparison among the cooling rates of the samples is shown in Fig. 11. The thickness of the ceiling sample directly affected the cross-sectional area available for heat to flow, which in turn governed the cooling rate of the sample location. The temperature decreased much slower and, in some instances, attained constant values as it approached the room temperature. Samples A2 and A4 had the highest cooling rate at 1.86oC/min, while sample A1 had the lowest cooling rate at 1.79oC/min. The cooling rate is dependent on the nature of the microstructure and composite material composition that readily releases heat or vice versa. It is important to note that the structure of a metal composite is determined by the thermal cooling history that leads to the final product [33]. Cooling history gives an insight to the crystallinity of polymer composites [34]. An investigator [35] reasoned that there is a strong correlation between cooling rate and crystallinity of carbon fibre composites, hence the tendency of cooling rate to alter the performance of carbon fibre/polyether ether ketone composites becomes pertinent.
3.1.5 Comparison mass retained after combustion
The materials in Fig. 12 showed significant mass conservation after combustion with little mass loss in the range of 1.8–2.41 g. The base materials and binders such as aluminium dross, cement, silicate, and carbon graphite changed slightly in physical appearance due to trace moisture in their composition. Reinforcement materials such as coconut shells, oil beanstalk, and eggshell degraded due to their flammability tendencies. Composite material A2 was most stable after combustion with 1.8 g loss of material compared to other materials due to the oil beanstalk reinforcement and residual moisture in the composite.