Increasing Percentage of Fiber Particles to Silicone Rubber without Changing Chemical Properties

 

Nallabelli Manogna*, Pulla Sammaiah, Bhumpelly Saiprasad

Department of Mechanical Engineering, S R Engineering College, Warangal, Telangana, India

 

ABSTRACT:

The liquid silicone rubber (LSR) composites use increasing in mechanical and electrical properties because of their wide applications.In this work, the chemical properties of the composite material which is made with the liquid silicone rubber and fiber filler. This composite may exposed to the environment because it is best suitable material to prepare an electrical insulation. The LSR composites are prepared in a normal room temperature and hand casting process. In this process the fiber scrap is used as filler and with the help of sieve shaker we have collected -75micron particle. Then the composites are prepared with 3mm, 4mm, 5mm, thickness samples on the base of fiber and hardener. The sample is not reacted with salt and acid tests. The electrical conductance of samples is increased in 1N, and 10N of NaCl solutions. The TDS of the solutions is increases then the electrical conductance of the solutions also increased. And there is no change of PH of the solutions and weight of the samples before 56hrs and after 56HRs.The increase in TDS of the solutions is increases the EC in all the solutions except the H₂SO₄ solution.

 

 

1. INTRODUCTION:

Re-cycling of a material is one of the best parts of the world because per day 0.82milions of plastic dump is produced by human around the world. So it sounds very good when recycling of a product or material comes into our account. So here the fiber scrap can be reused as filler to the liquid silicone rubber matrix. Some papers showed that the different filler materials are given good results in their different areas i.e. thermal, mechanical and electrical applications. So that the as liquid silicone rubber has special quantities which help us to use in many ways. Here in this project Liquid silicone rubber as matrix and fiber particles are fillers. it is very best suitable for filler material which is no cost, re-cycling of waste, and durable.

 

Yimin yioet al stated the packaging density of electronic devices increasing rapidly. Glass fiber reinforced polymer used as a substrates in printed circuit boards. The Al₂O₃ exhibits the highest improvement in thermal conductivity. This is attributed to the strong interfacial adhesion between Al₂O₃particles and polymer matrix. The glass fiber reinforced polymer composites are expected to be valuable in the integrated circuit package industry, especially for the heat release packaging materials for electronic circuits [1].G.momen et al stated that the Pure silicone rubber shows little tracking and erosion resistance. So some properties are needed to be improved to extend service life. The filler are added to the polymer to promote specific properties and also reduce cost. To improve the surface hydrophobicity, electrical conductivity, relative permittivity and thermal conductivity of polymeric materials, micro and nano fillers are added [2-3]. Han et al worked on the influence of aluminum trihydrate content and high temperature vulcanized silicone rubber on the electrical insulation properties, tracking and resistance. This ATH result showed that it contains 130phr (parts per hundred rubbers).  It increases the erosion resistance, tracking, arc resistance of silicone rubber. This ATH is widely used in housing materials for high voltage insulator. ATH to high temperature vulcanized (HTV) lead to better erosion resistance but declined mechanical properties.Silica which improves the physical properties of silicone rubber Meyer et al demonstrated that at low concentration the degree of protection of higher for the ATH filler. The amount of filler increases both of the ATH and silica fillers yield the same protection level.

 

Venkateshulu et al reported that the silicone rubber is filled with Magnesium dihdroxide nanoparticles has been result in the better performance of Magnesium Dihydroxid in terms of eroded mass, depth, width and length at this filler concentration.[4-5] Zinc oxide,This will increases the relative permittivity and also the thermal conductivity of the composite. Sim et al showed that ZnO filled silicone rubber exhibited better thermal performance compared to Al₂O₃ filler silicone rubber. ZnO fillers delays the curing process compared to Al₂O₃. [6-7]Titanium oxide, It is extensively utilized in environmental applications such as self cleaning, anti bacterial, waste water purification.Silva et al studied the improvement of the properties and photocatalytic characteristics of silicone rubber incorporated with TiO₂. Use of TiO₂ fillers in polymeric   materials also improves the thermal and electrical properties. So it is useful for archiving higher thermal conductivity and relative permittivity. Increasing the amount of TiO₂ led to decrease in the cross linking density of the matrix causing rubber to swell. Adding BaTiO₃ nanoparticles to polyimide also results in better thermal stability of the composite. Increasing in BaTiO3content led to higher decomposition temperature.E.A Cherneye et al stated thatthe mechanism of inorganic fillers in silicone rubber, enhance dielectric properties of thermal conductivity, relative permittivity and electrical conductivity making them useful in outdoor insulation. In outdoor applications electrical insulation often experiences stress.  Fillers used here is alumina trihydrate it is minimize the material erosion at dry band arcing sites. And use of antimony doped tin oxide filler binary composite and when applied as a housing material to outdoor bushings so that pollution performance is enhanced. By adding this fillers tracking and erosion resistance of silicone rubber composition for outdoor application improved.[8-9]

 

2. Experimental work:

3.1 Fiber particle preparation:

For preparation of fiber micro particle, sieve analysis is needed to be done. Fiber scrap collected from the optical shop, where lens finishing technician can through outside as fiber waste. That fiber scrap is sieved with different levels of meshes i.e. -150 microns, +75 microns. After 2hrs of sieve analysis three different size fiber particles are collected in the meshes. From that, the -75 microns of fiber particles are used as filler to the liquid silicone rubber matrix composite.

Fig.1 liquid silicone rubber, hardener, and fiber particles

 

3.2 Silicone rubber and hardener:

Silicone rubber is a highly adhesive gel or liquid at its uncured state. In order to convert liquid silicone rubber into solid, it must be cured, So that we need to add hardener to the silicone rubber. Here we are using platinum based curing system is used to get the liquid silicone rubber into solid. After adding of hardener to the silicone rubber it will take one day to convert into solid.

 

 

Fig.2 preparation of samples

 

3.3 sample preparation:

To prepare the samples by using fiber scrap we need to mix the fiber and hardener in different proportions to the silicone rubber. By adding fiber particles as filler, we are going to improve the properties of base material. By adding fiber and hardener in different proportions we observe different changes in the properties of silicone rubber.

 

Table.1 Composition of the samples

Sample number	Liquid silicone rubber (%)	Fiber scrap (%)	Hardener (%)
1	90	5	5
2	85	5	10
3	80	5	15
4	85	10	5
5	80	15	5

 

3.4 Chemical test:

Chemical tests like salt test, acid tests are conducted on the above samples. For salt tests we need to take the three different moles of salt solutions that are 0.1N, 1N, 2N. Here to prepare a 0.1N of sodium chloride solution 0.1of NaCl salt is added to the 100ml distilled water. Actual weight of NaCl added to the 100ml distilled water is 58gm on the basis of this proportion 0.1N, 1N and 2N.

For 0.1N concentration Nacl solution

Amount of NaCl=0.58gm

Amount of distilled water=100ml

For 1N concentration Nacl solution

Amount of NaCl=5.8gm

Amount of distilled water=100ml

For 2N concentration Nacl solution

Amount of NaCl=11.6gm

Amount of distilled water=100ml

Before immersing the sample in the above solutions, we weighted them with the help of sensitive balance and recorded. After the time intervals of 6hrs, 18 hrs, 24hrs removed the samples from solutions and waited for dry. After that we have weigh the samples and recorded the weight after 6hrs, 18hrs, and 24hrs again.

 

Also conducted electrical conductivity test, TDS, PH for the both solutions before sample was immerse and the solution after removed the sample.

 

3.5 HCl test:

 In acid test we have used the dilute HCl solution in that we immerse the sample up to 24hrs. So here for dilute HCl solution, we need to added 5.25ml of concentration HCl to the 12.5ml of distilled water.  Observed the samples and recorded the weights before immerse into the solution and after removed from the solution.

 

3.6 H₂SO₄ test:

For dilute H₂SO₄ solution we have added the 1.75ml of concentrated H₂SO₄ to the 12.5ml of distilled water. In this dilute solution samples are immersed for 24hrs and readings are noted down before immerse into solution and after removed from the solution.

 

Fig.4 Conducting Chemical tests

 

4. RESULTS AND DISCUSSION:

4.1 Chemical test:

The results of the sodium chloride test, acid tests are given positive result i.e. the samples are not reacted with the solution at any point. Samples also not reacted with the acids like HCl and H₂SO₄. Below tables shows the results of chemical analysis

 

From the above results, we observed that the samples are not reacted with any solution that we found from the tables how it means the weight before sample immersed into the solution and after removed from the solution has given same data. So the sample is not reacted with salt and acid tests.

 

4.2Electrical conductance, PH and TDS test:

Sample 1: LSR (90%) +Hardener (5%) +Fiber (5%)

 

Fig.5 Electrical conductance of the sample.1 with various                 Fig.6 Total Dissolved Solids of the sample.1 with various chemical

chemical solutions                                                                                     solutions

 

It show that the electrical conductance of samples is increased in 1N, and 10N of NaCl solutions, and in  remaining all the solutions the EC is decreased before and after 56 hrs, so that the decreasing of electrical conductance defines the dissolving of ions is less and the conduct of electricity also less in the electrolyte. The TDS of the solutions is increases then the electrical conductance of the solutions also increased. And there is no change of PH of the solutions and weight of the samples before 56hrs and after 56HRs.

 

Fig.7 PH Value of the sample.1 with various chemical solutions      Fig.8 Electrical conductance of the sample.2 with various chemical solutions

Sample 2: LSR (85%) +Hardener (10%) +Fiber (5%)

 

In this samples solutions it is observed that the TDS of the solutions increased in the 0.1N and 10N of Nacl solutions, so the EC of the solutions absolutely increases. And there is no change in PH Value of the solutions and weight of the samples

 

Fig9 Total Dissolved Solids of the sample.2 with various                   Fig.10 PH Value of the sample.2 with various chemical solutions

chemical solutions

 

Sample 3: LSR (80%) +Hardener (15%) +Fiber (5%)

In this Effect of the Hardener samples it is observed that the TDS of the solutions is increased in all the NaCl solutions where as in acids it is decreased. The Electrical Conductance also is increased in all the Nacl solutions and decreased in acid solutions. There is no change in Ph value and Weight of the samples before and after 56Hrs.

 

Fig.11 Electrical conductance of the sample.3 with various             Fig.12 Total Dissolved Solids of the sample.3 with various chemical  chemical solutions                                                                                     solutions

 

Fig.13 PH Value of the sample.3 with various chemical                 Fig.14 Electrical conductance of the sample.4 with various  chemical solutions                                                                                                 solutions

Sample 4: LSR (85%) +Hardener (5%) +Fiber (10%)

In this sample it is observed that the TDS and EC of the solutions are increased in all the solutions but in the H₂So₄ solution it is decreased.  And the PH value of the 10N Nacl solution is acidic state before samples immersed into the solution and base state after 56Hrs of time. There is no change in weight of the samples.

 

Fig.15 Total Dissolved Solids of the sample.4 with various                   Fig.16 PH Value of the sample.4 with various chemical solutions

chemical solutions

 

Sample 5: LSR (80%) +Hardener (5%) +Fiber (15%)

In these samples the increase in TDS of the solutions is increases the EC in all the solutions except the H₂So₄ solution. This results are similar to the above samples which is Effect of the fiber filler sample i.e. the composition of samples is LSR (80%) +Hardener (5%) +Fiber (15%).

 

Fig.17 Electrical conductance of the sample.5 with various         Fig.18 Total Dissolved Solids of the sample.5 with various chemical  chemical solutions                                                                               solutions

 

Fig.19 PH Value of the sample.5 with various chemical solutions

5. CONCLUSION:

It is observed that the effect of the hardener samples in sample-2 and sample-3 are given comparatively same and similar results in Electrical conductance, TDS and PH value.  The effect of the fiber particles in sample-4 and samples-5 are also given similar results in EC, TDS and PH value. There is no change in the weight of the samples before immersed into the solutions and after removal of solutions. It’s a keen observation that the liquid silicone rubber filled with fiber particles composite is not effectively react with the NaCl and acidic solutions. The results show that the composite is best suitable for the materials in salt and acid environments.

 

6. REFERENCES:

1.      Yiminyio, Xiaoliang zing, Kun guo, Rong sun, Jian bin Xu, The effect of interfacial state on the thermal conductivity of functionalized AL₂O₃ filled glass fibers reinforced polymer composites. (China). Composites: Part A 69 (2015) 49–55. http://dx.doi.org/10.1016/j.compositesa.2014.10.027.

2.      G. Momen, M. Farzaneh Survey of micro/ nano filler use to improve Silicone rubber for outdoor insulators.

3.       Hsien-Tang Chiu, Yung-Lung Liu, Chih-Wei Lin, Zhi-Jian Shong and Peir-An Tsai Thermal Conductivity And Electrical Conductivity Of Silicone Rubber Filled With Aluminum Nitride And AluminumDOI 10.1515/polyeng-2013-0025 J PolymEng 2013; 33(6): 545–549.

4.      B. Venkatesulul and M. Joy Thomas, Studies on the Tracking and Erosion Resistance of RTV Silicone Rubber Nanocomposite. 978-1-4244-2549-5/$25.00 ©) 2008 IEEE

5.      Dong-Hee Han, Dong-Jun Kang1, Dong-Pil Kang and Kyung-Eun Min. Characteristics of Electrical Insulation in PDMS-ATH Composite for High Voltage Insulators. Polymer Bulletin 61, 611–617 (2008) DOI 10.1007/s00289-008-0980-0

6.      Jun-Wei Zha, Zhi-Min Dang, Wei-Kang Li, Yan-Hui Zhu, George Chen, Effect of Micro-Si3N4–nano-Al2O3 Co-filled Particles on Thermal Conductivity, Dielectric and Mechanical Properties of Silicone Rubber Composites. IEEE Transactions on Dielectrics and Electrical Insulation Vol. 21, No. 4; August 2014

7.      L. C. Sim, C. K. Lee, S. R. Ramanan, H. Ismail & K. N. Seetharamu, Cure Characteristics, Mechanical and Thermal Properties of Al2O3 and ZnO Reinforced Silicone Rubber. Polymer-Plastics Technology and Engineering, 45:3, 301-307.

8.      E.A Cherney, Silicone rubber dielectric modified by inorganic fillers for outdoor high voltage insulation application. (Volume: 12, Issue: 6, Dec. 2005) https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=94

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Received on 26.10.2018           Accepted on 30.11.2018       ©A&V Publications all right reserved Research J. Engineering and Tech. 2018;9(4): 281-287. DOI: 10.5958/2321-581X.2018.00037.5