Results And Discussion

Results and Discussion

CHAPTER 4

RESULTS AND DISCUSSION 4.1 Characterization of Caco3, Caso4, Ca3(PO4)2 and Mg(OH)2 Nano Particles by XRD and TEM Figures 4.1a to 4.3c, XRD gram of different mineral fillers synthesized in polyethylene glycol, show that with increasing concentration of polyethylene glycol nano size of fillers decreases. The particle size of different ratios of PEG and calcium chloride (4:1, 20:1, and 32:1) were recorded as 23, 17, 11 nm for CaCO3 as well as 23, 15 and 10 nm and 21,17,11 for CaSO 4 and Ca3(PO4)2 respectively. Whereas the particle size of 4:1, 20:1, and 32:1 ratios of PEG and MgCl2 were recorded as 24, 20, and 11 nm for Mg(OH)2 respectively. Figs 4.1(ac), 4.2 (a-c), 4.3 (a-c) show the X-ray diffractograms of CaCO3, CaSO4, and Mg(OH)2 particles respectively. Figs 4.4 (a-c), 4.5 (a-c), 4.6 (a-c) and 4.7 (a-c) shows the TEM of CaCO3, CaSO4, Ca3(PO4)2

and

Mg(OH)2

particles

respectively. The TEM study represents the actual size of particle rather than XRD. Table 4.1 shows the particle size and yields of nano CaCO3, CaSO4, and Mg(OH)2.

The size of nano particle was confirmed using Scherer’s formula (1-

11), which is given below Particle Size d (Ao) = k. λ / ∆2θ Cos θ k = Order of Reflection λ =1.542 θ = Diffraction Angle ∆2θ = Full Width at Half Maximum (FWHM) Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

It is observed that with increasing molar ration of PEG the nano size reduces. The XRD peaks become broader which is major indication of reduction in nano size. The broadening of peak may be due to vigorous mixing at molecular level. It is has been reported (1) that the usual precipitation method is not suitable to bring constrains on the phases, even change in the temperature also makes the variation in nano size and structures for both cases i. e in situ deposition and conventional precipitation methods (6-11). So in situ deposition method have been used by cooling hot water soluble polymer mixture to the room temperature. The shape and size of nano particles were confirmed by TEM (Fig 4.4 a-c) to 4.7 (a-c).

The particle shape of nano CaCO3 is spherical, while CaSO4 having

needle like structure. Whereas shape of nano Mg(OH)2 is uneven or say spherical.

Fig 4.1 a: X-ray Diffractogram of 21 nm CaCO3

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.1 b: X-ray Diffractogram of 15 nm CaCO3

Fig 4.1 c: X-ray Diffractogram of 9 nm CaCO3

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.2a: X-ray Diffractogram of 10 nm CaSO4

Fig 4.2b: X-ray Diffractogram of 15 nm CaSO4

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.2c: X-ray Diffractogram of 23 nm CaSO4

Fig 4.3a: X-ray Diffractogram of 24 nm Mg(OH)2

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.3b: X-ray Diffractogram of 17 nm Mg(OH)2

Fig 4.3c: X-ray Diffractogram of 10 nm Mg(OH)2

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.4 a: TEM Image of Nano CaCO3 (11 nm)

Fig 4.4 b: TEM Image of Nano CaCO3 (17 nm)

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.4 c: TEM Image of Nano CaCO3 (23 nm)

Fig 4.5 a: TEM image of Nano CaSO4 particle (30 nm)

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.6 a -TEM image of 24 nm Mg(OH)2

Fig 4.6 b -TEM image of 20nm Mg(OH)2

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.6 c- TEM image of 11 nm Mg(OH)2

Fig 4.7 a -TEM image of 24 nm Ca3(PO4)2

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.7 b -TEM image of 20 nm Ca3(PO4)2

Fig 4.7 c -TEM image of 11 nm Ca3(PO4)2

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Table 4.1: Yields and Particle Size of Nano Particles Nano filler

Molar ration of

Yields %

Particle size nm

reactant 4:1

87

23

20:1

65

17

32:1 4:1

55 87

11 23

20:1

65

15

32:1 4:1

53 85

10 24

20:1

62

20

32:1 4:1

51 87

11 21

20:1

65

17

32:1

55

11

PEG and Nano CaCO3

Nano CaSO4

Nano Mg(OH)2

Nano Ca3(PO4)2

4.2 PA: Nano CaCO3 Composites The amount of nano particles is a very important phenomenon for improvement in properties due to their size and dispersion. Considering this view the composites of PA nano CaCO3 were synthesized by taking very less amount of filler i.e. in the range of 1 to 4 % in the matrix. The properties of these composites were determined. 4.2.1 Mechanical Properties of nano CaCO3: PA composites 4.2.1.1 Tensile strength of nano CaCO3: PA composites

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

A relation between weight percentage of filler loading (nano and Commercial CaCO3) and tensile strength of polyamide composites is shown in fig 4.8. The tensile strength of nano CaCO3 filled polyamide nanocomposites is recorded higher than that of commercial CaCO3 filled polyamide composites. Also the tensile strength of 11 nm CaCO3 is found to be more improved than that of 23 and 17 nm sizes of CaCO 3. The tensile strength is recorded to be 103 and 96 MPa for 1 wt % loading of 11 nm CaCO3 and commercial CaCO3 respectively. Whereas, 4 wt % loading of 11 nm CaCO3 and commercial CaCO3 shows the tensile strength 121 and 102 MPa respectively. It means nano filler provides higher tensile strength

compared to commercial CaCO3. This increment in tensile

strength is due to uniform dispersion of nano filler throughout the matrix (6-11). Also due to reduction in particle size of CaCO3 that forms smaller spherullites for shorter period of time (7, 8). Moreover, during processing, rate of transfer of heat is uniform from particle to particle due to fine sizes of nano CaCO3, which leads in formation of composite without any failure (9, 10).

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.8: Tensile strength of different sizes of CaCO3 filled PA

4.2.1.2 Elongation at break of nano CaCO3: PA composites Fig 4.9 shows elongation at break of polyamide nanocomposites with varying wt % loading. With increase in weight percentage of filler loading, elongation at break decreases. There is continuous decrement in elongation at break with increase in amount of filler loading for all compositions. 11 nm CaCO 3 filled polyamide composite shows more decrement in elongation at break compared to other sizes of CaCO3. This might be due to hard nature of polyamide as well as nano inorganic filler. 1 % loadings of commercial, 23, 17 and 11 nm CaCO 3 show elongation at break 20, 18, 16 and 14 % respectively Whereas, 4 wt % loadings of commercial, 23,17, and 11 nm CaCO3 illustrate elongation at break as 15,13, 10 and 8 % respectively. Addition of filler decreases the elongation at break of composites. This is due to the increment in numbers of spherullites formation with reduction in size and increase in percentage of filler. Moreover it provides catastrophic failure to the specimen with crack propagation, and thus decreases Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

the extensibility of the composite. This crack development (12) is evidenced by AFM Figs 4.14a & 14b.

Fig 4.9: Elongation at break of different sizes of CaCO3 filled PA

4.2.1.3 Young’s Modulus of nano CaCO3: PA composites The young’s modulus of nano CaCO3 filled polyamide nanocomposites is recorded higher than that of commercial CaCO3 filled polyamide composites (fig .4.10). The Young’s modulus of 11 nm CaCO3 filled polyamide is found to be more than that of 23 and 17 nm sizes of CaCO3. 1 wt % loading of 11 nm CaCO3 shows young’s modulus as 3800 MPa, while 3650 MPa for same wt % of loading of commercial CaCO3; whereas, 4 wt % loading of 11 nm CaCO3 and commercial CaCO3

shows Young’s modulus as 4000 and 3725 MPa respectively, which is

three times greater than the commercial CaCO3 filled in polyamide and approximately far greater than virgin polyamide

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.10: Young’s Modulus of different sizes of CaCO3 filled PA

4.2.2 Physical properties of nano CaCO3: PA composites 4.2.2.1 Hardness of nano CaCO3: PA composites Figure 4.11 illustrates the effect of weight percentage of filler loading (nano and Commercial CaCO3) on hardness of polyamide composites. Like increment in young’s modulus, the hardness of nano CaCO3 filled polyamide nanocomposites is also recorded greater than that of commercial CaCO3 filled polyamide composites. The hardness of 11 nm CaCO3 filled composites is found to be more improved than that of 17 and 23 nm sizes of CaCO3. 1 wt % loading of 11 nm and commercial CaCO3 illustrates the hardness as

86 and 77 respectively,

while 4 wt % loadings of 11 nm and commercial CaCO3 showed 98 and 82

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

respectively. This might be due to uniform dispersion of nano CaCO 3, which makes the surface of the composite hard and tough.

Fig 4.11: Hardness of different sizes of CaCO3 filled PA

4.2.3 Thermal properties of nano CaCO3: PA composites 4.2.3.1 Thermal gravimetric analysis of nano CaCO3: PA composites Fig 4.12 (a-c) shows thermal properties of pristine, commercial CaCO 3 and nano CaCO3 (23, 17, and 11 nm) filled polyamide composites. The incorporation of nano CaCO3 into polyamide composites with reduced particle size shows better thermal stability than that of commercial CaCO3 filled polyamide composite. 23, 17, 11 nm CaCO3 fill composites show decomposition temperatures as 500, 520, and 542 oC at 1 wt % loading, while 4 wt % loading shows decomposition temperatures, 543, 557 and 570 oC respectively. The enhancement in thermal

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

stability is due to uniform dispersion and reduced particle size of nano CaCO3, which is responsible for the uniform absorption of heat and prevent diffusion of volatile decomposition products. It can be summarized from the results that the reduced nanosizes of CaCO3 provides better thermal, and mechanical properties than that of commercial CaCO3 in polyamide- 6,6. It is also observed from morphological study that the nanoparticles dispersed uniformly throughout the matrix up to 4-wt % loading. Thus heat absorption is more due to uniform dispersion of nanoparticles.

Fig- 4.12a: TGA thermogram of nano CaCO3 (23 nm) with varying wt %.

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig- 4.12b: TGA thermogram of nano CaCO3 (17 nm) with varying wt %

Fig- 4.12c: TGA thermogram of nano CaCO3 (11 nm) with varying wt %. Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

4.2.3.2 Flame retardancy (FR) of nano CaCO3: PA composites The rates of flame retardency of various filler compositions are shown in fig 4.13.The nanosize CaCO3 filled in polyamide shows significant improvement in flame retartdency compared to that of commercial CaCO 3 filled polyamide. The flammability values are 3.4 and 2.5 sec/mm for 1 wt % of 11 nm size CaCO 3 and commercial CaCO3 respectively. It means, reduction in nanosize shows better improvement in flame retarding properties. It is due to the uniform dispersion of nano particles in the matrix, which responsible for absorption of heat(13,14). More over the polymeric material get charred which acts as insulating agent to the matrix.

Fig 4.13: Rate of flame retardency of different sizes of CaCO3 filled PA Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

The AFM of 1 wt. % filled nano CaCO3 and commercial CaCO3 in PA show that the dispersion of nano particles is more uniform in case of nano CaCO 3 in comparison to commercial CaCO3 in PA (fig 4.14 a and b). Uniform dispersion of filler is responsible for improvement in mechanical, physical and thermal properties of CaCO3: PA composites. As the nano size is very small so that its small amount disperses uniformly in the matrix and intercalates the rubber chains to provide them in an order, and therefore surface area of rubber chains increases. However, a higher amount of nano CaCO3 may get agglomerated and therefore the behavior of agglomerated part of nano CaCO3 may be assumed as commercial CaCO3, which is less dispersed in comparison to nano CaCO3 in the matrix.

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.14 a: AFM of 2 wt % filled commercial CaCO3 in PA

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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Results and Discussion

Fig 4.14 b: AFM of 2 wt % filled commercial CaCO3 in PA in 3D view.

Ph.D Thesis, Mr. Shriram S. Sonawane, UDCT, North Maharashtra University, Jalgaon

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