1. Introduction Coagulation References Definition Contribution Activity Natural Rubber Objectives This webpage for form five science students

4. Family : Euphorbiaceae Genus : Hevea Species : brasiliensis Common Names : Rubber tree Synonyms : Siphonia brasiliensis Willd. ex A. Juss. Part Used : Leaves, bark, latex Rubber Click this for more info http://encarta.msn.com/text_761556347__1/Rubber.html ??????

5. Natural polymer : Natural rubber Monomer : Isoprene (2-methybuta-1,3-diene) Structural formula : Rubber ??????

7. Rubber Knives use by rubber taper Rubber tree seeds Click here for more information: - Uses of natural rubber ??????

8. Uses of natural rubber More information natural rubber products: - http://www.industrialrubbergoods.com/naturalrubber.html Dialysis catheters gloves Condom Balloons HOME NEXT BACK ??????

9. Natural rubber is a natural polymer Coagulation Rubber coagulation In Rubber Estate In Laboratory ??????

10. Coagulation: In Laboratory Apparatus: Materials: Procedure: Beaker, glass rod and dropper Fresh latex, dilute ethanoic acid, dilute ammonia solution, red and blue litmus paper. A C B Latex Latex + CH 3 COOH Latex + NH 3

11. Coagulation: In Laboratory Procedure: 1. Three small beakers are cleaned and labeled as A, B and C respectively. 2. About 50 cm3 of latex are placed in each beaker. 3. Using a dropper, a few drops of dilute ethanoic acid (acetic acid) are added to the latex in beaker B. The mixture is stirred with a glass rod. 4. The addition of ethanoic acid is continued until the latex become acidic. The acidity of latex is tested using a piece of blue litmus paper. 5. Ammonia solution is added slowly to beaker C until the latex become alkaline. The alkalinity of the latex is tested using a red litmus paper. 6. The three beakers are set aside for one to two days. The changes that take place in each beaker are recorded from time to time.

12. Coagulation: In Laboratory Results: Latex does not coagulate (no visible change) C Coagulation of latex occurs rapidly. B Coagulation of latex occurs slowly. A Observation Beaker

13. Coagulation: In Rubber Estate - http://sarawak-rubbertapper.tripod.com/process.htm Rubber tapping process: - http://www.bio.ilstu.edu/armstrong/syllabi/rubber/rubber.htm ??????

14. Coagulation: In Rubber Estate - http://sarawak-rubbertapper.tripod.com/process.htm Rubber tapping process: - http://www.bio.ilstu.edu/armstrong/syllabi/rubber/rubber.htm ??????

15. Coagulation: Mechanism H + rubber particle Broken protein membrane Long chain. (Rubber molecule) Breakage of protein membrane The coagulation of latex mechanism explanations ??????

16. Coagulation: Mechanism explanations Do you know how to prevent coagulation? ??????

17. Preventing Coagulation

19. Contributions More information RRIM: - http://www.lgm.gov.my/services/upb/upb_main.htm Do you know? In the future, it would be more expensive to produce synthetic rubber due to the rising cost and depleting source of petroleum. So, the natural rubber will turn into big demand. - RRIM (Rubber Research Institute of Malaysia) provide analytical services for the Research Centre, and to external clients. Video make tyre ??????

20. Vulcanization: The physical properties of the rubber can be improved by heating it with sulphur powder . Definition of vulcanization ??????

22. Vulcanization: Experiment RESULT Comparing the properties of vulcanized rubber with unvulcanized rubber

23. Vulcanization: Experiment RESULT Vulcanized rubber Unvulcanized rubber Final length when weight is removed (cm) Increase in length (cm) Final length when weight is hung (cm) Original length (cm) Type of rubber

24. Activity 1. Which of the following statements about vulcanization of natural rubber are correct? I Vulcanisation produces a rubber that is more elastic II Sulphur cross-links are formed between the chains of rubber molecules III Carbon atoms form cross-links between rubber molecules IV The long rubber molecules are broken up to form small molecules A. I and II B. I, II and III C. I, III and IV D. I, II, III and IV Answer