Study the Effect of Fiber Particles in Silicone Rubber to Improve the Mechanical Properties

 

Bhumpelly Saiprasad*, Pulla Sammaiah, Nallabelli Manogna

 

ABSTRACT:

In this project we have found that the mechanical properties of tensile strength and hardness are increases on the basis of effect of fiber and effect of hardener in a liquid silicone rubber matrix. The percentage of hardener increases with increasing the hardness of the silicone rubber composite. The composite consists of 15% hardener has given higher hardness compared to 10% and 5% of hardener. The condition at 80% of silicone rubber, 5% of hardener, 15% of fiber showed higher hardness compare to the other conditions. The thickness of composites increases then the strength of the composites also increased.

 

 

1. INTRODUCTION:

In our day to day life most of us dumping or throwing waste outside in the form of chemical waste or bio waste or plastic waste. It is very difficult for the people to live on earth in future because as the population of world increase the wastage also increases through which we can face more problems mainly health issues. Because the waste material in the form of large scale and small scale, of course the large scale waste is not much harmful to the people compare to the small scale, because small scale in the range of microns to nano level so it can create more problems. And that waste also effects the environment in a non-degradable waste. To overcome these issues re-use of micro level waste into useful one. It is a best solution for all the problems so to decrease or less dumping of waste we should take the action of re-use of waste material into useful one. It’s a best treatment to the world and environment

 

In generally the technicians of optical grinding, after finishing out the lens, they throw out the fiber scrap outside in environment. So that micro/nano particles can mix in environment and pollute it. That fiber scrap has collected from the optical shops and it can use as filler in my project and the liquid silicone rubber is a matrix. As we know liquid silicone rubber has more applications in many fields so here we have used these two materials and prepares a sample to improve the strength, hardness.P.Song, Z-J Peng et al stated that the mechanical properties like tensile strength, hardness, and tear strength are increases with increasing of the filler in the RTV matrix when the samples are keeping in the magnetic field while curing. In their paper they used RTV (room temperature liquid silicone rubber) as a matrix and Ni micro (in the range of 10-20micro meter) and nano (100-200 nanometer) particles as fillers. While curing the samples the micro/nano Ni particles are aligned in a magnetic field direction in a 600seconds. When the samples are tested as per the properties discussed above, the aligned nano filler gives much more result in tensile strength, modulus of 100%strain and tear strength compare to aligned and random micro fillers samples [1-3].

 

Eungsookim et al studied that the mechanical properties of composite material (which was prepared with the liquid silicone rubber as matrix, carbon fiber and silicone carbide powder as a fillers) has enhanced with increasing the fillers. Also increases ablation properties on the rocket combustion system and improves the life of the combustion system. The samples were prepared in a normal process, and cured in a woven at 150 degree centigrade. They developed a new process to find out the oblation properties i.e. the specimen was hinged with a load and at the centre of the sample the oxy acetylene flame has burnt the sample so the time taken from burn the sample and fail off the samples were calculated. The tensile and elongation of break properties were calculated which results, the pure silicone rubber samples has high strength than the added filler i.e. CF/SCF. The hardness of the silicone rubber sample is comparatively low with increasing the fiber content in the liquid silicone rubber matrix [4]Hsien-Tang chiu stated that the thermal conductivity of the liquid silicone rubber sample is increases with increasing the filler’s particles size. From this in some cases the particle size of the filler may affect the thermal conductivity of liquid silicone rubber sample. And that cannot depend on the property of coefficient of thermal conductivity of filler. In his paper found that the development of the new sample with Al and AlN fillers were mixed in the LSR sample given good results in high temperature environments. The electrical conductivity of the samples is increased with increasing the Al filler particles [5-6]. Theorder et al stated that the mixtures of other liquid silicone rubber materials which have different viscosities may be used. In that additives like fillers, colors, coolants, softeners, thixotropic agents, wetting agents, adhesion promoters, catalysts and others   to be added to the liquid silicone rubber. Both reinforcing and non reinforcing fillers may be used as fillers. he also preferred that the inorganic fillers are highly disperse, pyrogenic, or precipitate silica acids, carbon block, chalk, metal oxides such as titanium oxides for decorative and hydrophobic purposes. He also preferred that the tin based catalysts i.e. tin-organic compounds such as dibutyl tin difaurate, dibutyl tin divaleriate, dibutyl tin diacetate, dibutyl tin dineodecanoate. and titanium based, zirconium based, aluminum based compounds may  used as catalysts for silicone rubber, these compounds stored for more than 12months of period under exclusion of moisture and these are more advantages to the composite materials which are prepared with the silicone rubber materials. When the both silicone rubber and catalysts mixed for composite material which releases ethylelactane which is an oxime compounds i.e. butane 2-oxime compound which is not hazardous, and non corrosive, do not react with any metal, mortar, stone [7-8].G. Rajesh et al stated that the Liquid silicone rubber properly cured with the ratio 4:1 for U10 and 2:1 for U65. Here U10 and U65 are the mixing of different proportions of liquid silicone rubber and platinum curing agent. Hence the above two different mixtures are given good results while compare to the ratio of 1:1 liquid silicone rubber and curing agent. It also observed that the mechanical properties and thermal properties of the above samples show more improvements [9].

 

2. EXPERIMENTAL WORK:

2.1. Fiber Particle Preparation:

In this particle analysis, the fiber scrap can be separated with different thicknesses by using the sieve shaker. We collected the fiber scrap from the optical shop, where the lens finishing should takes place by removing of the fiber scrap. So that scrap is separated in different thicknesses with the help of the sieve shaker. In the sieve shaker we have used 150, 75 meshes to separate the particles, the separated particles are in -75µ, +75µ, -150µ, +150µ level. Here in this work we used -75µ fiber particles as filler.

 

2.2. MATERIALS AND METHODS:

The liquid silicone rubber samples are prepared by hand molding process by using a die of mild steel with the dimensions of 100×100×5 mm. The samples are prepared on the basis of filler and hardener.  In the effect of hardener the fiber should constant and hardener will be varied and in the effect of fiber vice versa. After 24hrs of curing time in room temperature, samples are removed from the die. The tensile test and hardness tests are conducted on the samples. For tensile test the samples are cut as per the ASTM standard. Hardness test also done on the samples with the help of shore A hardness tester as per ASTM 2240. Chemical test like NaCl, HCl, H₂SO₄, corrosion, electrical conductance tests are done on the samples which gives positives result i.e. the samples are not reacted with the above chemicals.

 

Liquid silicone rubber along with curing agent (Platinum based curing agent)are used. Fiber particles were collected from the optical shop. Before separated as micro particle it is a scrap that can be filtered i.e. sieve analysis has to be done for fiber scrap. Then the -75 micron fiber particles are collected and packed in sealed cover. With the help of G.I sheet the dies are prepared on respected dimensions 100×100×5mm. the subsequent casting process is done on the base of effect of fiber and effect of hardener. Table.1 shows the effect of fiber particles in the sample and Table.2 show that the effect of the hardener in the sample. The samples are made up of with different thickness like 3mm, 4mmand 5mm thickness.

 

 

Table 1: Parameters are selected at constant hardener

S.No	LSR (%)	FIBER (%)	HARDENER (%)
1	90	5	5
2	85	10	5
3	80	15	5

 

Table 2: Parameters are selected at constant fiber

S.No	LSR (%)	FIBER (%)	HARDENER (%)
1	90	5	5
2	85	5	10
3	80	5	15

 

2.3. Mechanical Test:

The hardness test is conducted with the help of Shore-A hardness tester as per the ASTM D2240. Shore-A hardness tester used to measure the polymer or rubber materials hardness. In the MSME testing station the operator measured the hardness for the above sample as shown in Figure 1 and the results are observed and noted it down in the Table 3.

 

Fig, 1: Hardness testing on Silicone Rubber at MSME, Hyderabad

 

Tensile tests also conducted in the MSME Testing station. All the tests are conducted with the help of UTM 2500N as shown in Figure 2. The above prepared samples are cut as per the dimensions of tensile test.

 

Fig. 2: Tensile Testing on Silicone Rubber at MSME, Hyderabad

 

 

Table3: Hardness of the Silicone Rubber without filler material

S. No	LSR + Hardener	Hardness	Tensile stress (N/mm2 )
Sample1	95%+5%	35	2.6574
Sample2	90%+10%	38	2.5782
Sample3	85%+15%	41	3.2945

 

Table 4: Hardness and Tensile strength of the samples with effect of hardener

S. No	LSR + Hardener + fiber	Thickness
		3mm	4mm	5mm	3mm	4mm	5mm
		Hardness			Tensile stress (N/mm2 )
Sample1	90%+5%+5%	43	42	44	2.9776	2.1897	2.2239
Sample2	85%+10%+5%	47	47	41	2.8142	2.6918	2.7695
Sample3	80%+15%+5%	45	47	49	2.9441	2.7614	2.7904

 

Table 5: Hardness and Tensile strength of the samples with effect of fiber particles

S. No	LSR + Hardener + fiber	Thickness
		3mm	4mm	5mm	3mm	4mm	5mm
		Hardness			Tensile stress (N/mm2 )
Sample1	90%+5%+5%	43	42	44	2.9776	2.1897	2.2239
Sample2	85%+5%+10%	22	49	50	1.0470	2.7999	2.7156
Sample3	80%+5%+15%	52	53	56	2.8779	3.2128	3.0164

 

3. RESULTS AND DISCUSSIONS:

3.1. Mechanical Properties:

The mechanical properties of the silicone rubber show tremendous improvement with addition of percentage of hardener and fiber particles with variation in size.

3mm thickness samples without filler material

 

Figure1: Graphical representation of hardness value of the 3mm thickness sample without filler

 

Table 1 show that the percentage of hardener increases the hardness value of the sample. The sample which has the 15% hardener has given more hardness value compare to the 10% and 5% of hardener samples.

 

3mm thickness samples with filler material:

1) Effect of the hardener

Table 4 show that the hardness value of the sample is increased which is contained the 85% of Silicone Rubber, 10% hardener, and 5% of fiber filler. In this effect of the hardener samples the hardener of 10% has given much hardness value.

2) Effect of the fiber

Figure 2: Graphical representation of hardness value of the 3mm thickness sample with filler

Table 5 shows that the effect of the fiber filler may increases the hardness value, from above table which is given that the sample has 80% of Silicone rubber, 5% of hardener, 15% of fiber filler is more hardness value compare to the other.

 

4mm thickness samples with filler material:

1) Effect of the hardener

 

Table 6 shows that, the percentage of the hardener increase in the sample then the hardness value also increased.  From Figure 4 the graphical representation of hardness properties on the effect of hardener with thickness of 4mm samples shows that a increasing line of hardness value.

 

2) Effect of the fiber

 

Figure 3: Graphical representation of hardness value of the 4mm thickness sample with filler

 

Table 7 shows that the increasing of fiber filler percentage may increase the hardness value. It can also observe from the graphical representation of the hardness properties.

 

5mm thickness samples with filler material:

1) Effect of the hardener

Table 8 show that the sample which has the more hardener percentage in the above sample i.e. 80% of silicone rubber, 5% of fiber, 15% of hardener given more hardness value.

2) Effect of the fiber

 

Figure 4: Graphical representation of hardness value of the 5mm thickness sample with filler

 

From the table 9 the hardness value increased in the sample when fiber filler increase.

3.2 Tensile Strength:

 

Figure 5: Graphical representation of the tensile stress results of 3mm thickness sample without filler

 

Figure 6: Graphical representation of the tensile stress results of 3mm thickness sample with filler

 

The above graphical representation of the tensile stress results of 3mm thickness sample with filler material shows that the effect of hardener given more strength compare to the effect of fiber. It can also observed that the thickness may affect the results i.e. in 3mm thickness sample the defects of formation of bubbles and voids created while curing so to avoid this defects we need to use the magnetic stirrer and vacuum chamber.

 

Figure 7: Graphical representation of the tensile stress results of 4mm thickness sample with filler

 

From the above results it is observed that the tensile stress of the 4mm thickness sample increases with increasing of the percentage of fiber and hardener respectively.

2) Effect of the fiber

Figure 8: Graphical representation of the tensile stress results of 5mm thickness sample with filler

 

From the above tensile strength results, when the percentage of hardener and fiber filler increased the tensile strength also increases with respect of the fiber filler and hardener. It can also observe that the tensile strength of the sample may depend on the thickness of the sample.

 

CONCLUSION:

Liquid silicone rubber composites are prepared on the basis of filler material and thickness. It’s also observed that the mechanical properties of the samples with effect of fiber particles samples are given better result compared with the effect of hardener sample. So it is clearly observed that the hardness and tensile strength of the fiber particle filler samples are much better in the 4mm and 5mm thickness samples. Also observed that when the thickness of sample increases then the corresponding strength of the fiber sample also increased.

 

REFERENCES:

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Received on 12.10.2018            Accepted on 29.11.2018      ©A&V Publications all right reserved Research J. Engineering and Tech. 2018;9(4): 297-303. DOI:  10.5958/2321-581X.2018.00040.5