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Phenolic resins,
- 1. PHENOLIC RESINS MUHAMMED MUSTHAFAC.P 6TH SEM , DEPT. OF PS&RT CUSAT
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- 3. History 1872 Germanchemist Adolf von Baeyer reported reaction between phenol and aldehyde Synthesized by Leo Hendrik Baekeland in 1907 1910 oil-soluble modified phenolic resins produced by beherends 1911 Bakelite company came under operations
- 4. Introduction The phenolicresins may be considered to be the first polymeric products produced commercially from simple compounds of low molecular weight, they were the first truly synthetic resins to be exploited.
- 5. Phenolic resinsare also widely known as phenol-formaldehyde resins, PF resins and phenoplasts. The trade name Bakelite has in the past been ideally used
- 6. The phenolicsare resinous materials produced by condensation of a phenol, or mixture of phenols, with an aldehyde Manufacture
- 7. RAW MATERIALS :-a) Phenol b) Aldehyde HCHO
- 8. TWO TYPES NOVOLAK Preparedby reacting phenol with formaldehyde in a molar ratio of approximately (1 :0.8) under acidic conditions. Slow formation Fast condensation Two stage resin Absence of active methylol group RESOL Produced by reacting a phenol with an excess of aldehyde in a molar ratio of (1.5-2:1) under basic conditions Rapid formations Slow condensation One stage resin Presents of methylol group
- 9. RESIN MANUFACTURE Inthe manufacture of novolaks, 1 mole of phenol is reacted with about 0.8 mole of formaldehyde (added as 37% w/w formalin) in the presence of some acid as catalyst. A typical charge ratio would be: PHENOL 100 PARTS BY WEIGHT FORMALIN 75 PARTS BY WEIGHT OXALIC ACID 1.5 PARTS BY WEIGHT
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- 11. The reactionmixture is heated and allowed to reflux, under atmospheric pressure at about 100°C. At this stage valve A is open and valve B is closed. Because the reaction is strongly exothermic initially it may be necessary to use cooling water in the jacket at this stage.
- 12. The condensationreaction will take a number of hours eg: 2-4hrs. since under the acidic conditions the formation of phenol-alcohols is rather slow. When the resin separates from the aqueous phase and the resin reaches the requisite degree of condensation, as indicated by the refractive index measurements, Then the valves are changed over (ie. valve A is closed and valve B opened) and water present is distilled off.
- 13. Properties Available assolids and solutions Solubility depends on the structure of the solution Decomposition temperature range is 120-250˚c Electrically insulating Good dimensional ability on heating Poor conductor of heat Retain properties at freezing temperature
- 14. Applications Phenolic resinsare mainly used in the circuit board production that is for making circuit board like PCB ….etc
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- 16. Engine ignitionequipment
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- 19. REFERENCE J.A BRYDSON(1999) PLASTIC MATERIAL (7TH EDITION) WIKIPEDIA
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