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Nondestructive testing of defects in adhesive joints

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Effect <strong>of</strong> electron beam cur<strong>in</strong>g on mechanical and electrical properties <strong>of</strong><br />

silica filled silicone and FKM rubber and its comparison with chemical<br />

cur<strong>in</strong>g<br />

Introduction:<br />

R.K. Ramamoorthy, K. Naskar, D Khastgir *<br />

Rubber Technology centre, IIT Kharagpur-721302, INDIA<br />

Email: dkhastgir@yahoo.co.uk, khasdi@rtc.iitkgp.ernet.<strong>in</strong><br />

The treatment <strong>of</strong> polymers by an electron beam has been reviewed different authors<br />

[11-14]. It is observed that , <strong>in</strong> general, rubbers can be cross-l<strong>in</strong>ked us<strong>in</strong>g an electron<br />

beam(EB) , where as some plastics like polypropylene and poly(v<strong>in</strong>yl chloride ) have a<br />

tendency to degrade[13,14].<br />

The effects <strong>of</strong> electron beam (EB) irradiation on mechanical and electrical<br />

properties <strong>of</strong> Silicone rubber (MQ), and Fluro rubber (FKM) compounds filled with<br />

Precipitated and Fumed Silica filler have been reported <strong>in</strong> the present paper. The effect <strong>of</strong><br />

different degree <strong>of</strong> radiation dosage on both electrical and mechanical properties was<br />

<strong>in</strong>vestigated. Some comparison has been made between properties <strong>of</strong> EB cured vulanizates<br />

<strong>of</strong> theses two rubbers with Peroxide cured Silicon rubber and Calcium hydroxide cured<br />

FKM rubber. The type <strong>of</strong> silica filler used affects both electrical and mechanical properties<br />

<strong>of</strong> EB cured vulcanizates.<br />

Experimental:<br />

All mix<strong>in</strong>g was carried out <strong>in</strong> laboratory size open mix<strong>in</strong>g mill <strong>in</strong> accordance with the<br />

formulations given <strong>in</strong> table1-3 under identical condition <strong>of</strong> time, temperature and friction<br />

ratio. Some samples were subjected to electron beam cur<strong>in</strong>g with various dosage <strong>of</strong><br />

radiation level and other samples are chemically cured up to optimum cure time us<strong>in</strong>g<br />

electrically heated press. Gel fraction and different mechanical and physical properties<br />

were measure <strong>in</strong> accordance with standard ASTM methods.<br />

Table1.Formulation for Electron Beam Irradiation Cure<br />

Ingredient Q Q FKM FKM<br />

Precipitated Silica (phr) 20 - 20 -<br />

Fumed silica (phr) - 20 - 20<br />

TQ (phr) 2 2 2 2<br />

Sunpar Oil (phr) 2 2 2 2

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