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PowerPoint Training Slides Used By John Woon Latex Consultants

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Examples of PowerPoint Slides used by John Woon Latex Consultants for Training of Latex Technologists

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PowerPoint Training Slides Used By John Woon Latex Consultants

  1. 1. Examples of Training Slides Used by John Woon Latex Consultants
  2. 2. NR LATEX PROPERTIES (Hevea Brasiliensis) John Woon Sung-Liang JW Latex Consultants http://latexconsultants.blogsp ot.com
  3. 3. NR LATEX PROPERTIES (Hevea Brasiliensis) - - ESSENTIALLY A HYDROSOL CONSISTING OF A 2-PHASE SYSTEM NAMELY :- 1. DISPERSE PHASE OF RUBBER PARTICLES (ALSO KNOWN AS DISCRETE PHASE, DISCONTINUOS PHASE OR INTERNAL PHASE) 2. DISPERSION MEDIUM (ALSO KNOWN AS AQUEOUS, CONTINUOUS OR EXTERNAL PHASE) * DENSITY OF DISPERSE PHASE 0.92 g/cc • DENSITY OF DISPERSION MEDIUM 1.02 g/cc
  4. 4. STABILITY OF LATEX John Woon Sung-Liang http://latexconsultants.blogspot.com 1. Presence of - ve Charges on Rubber Particle Surfaces Due to Protein/Lipid Layers. Mutual Coulombic Repulsion. PROTEIN LIPID PROTEIN (HYDROLYSED TO FATTY ACID RH/C SOAP IN PRESENCE OF NH 3) RH/C Repulsion P = Polar side chain OS- of Protein N P- OS- N = Non-polar side N OS =Soap chain of protein P- Molecule OS- N P-
  5. 5.  What is Nitrile or Buna-N or NBR Rubber?  By John Woon Sung-Liang  JW Latex Consultants (SA0052392P)  http://latexconsultants.blogspot.com  Email: woonsungliang@yahoo.com.sg
  6. 6. WHY Use NBR?  Mainly because of the presence of Acrylonitrile  Acrylonitrile content can be:  Low (25%)  Medium (33%) and  High (45%) *
  7. 7. Acrylonitrile vs Tg (Tg = -10C to -55C)  -10  -20  -30   - 40  Tg (Degree C)  -50  -60  10 20 30 40 50 60  Acrylonitrile level (%)
  8. 8. Main Differences in Processing Compared with NR  1) pH adjustment  - Sensitive ……...  - If below 9.0 …………  - If above 9.8 …………  Alkali must be added ………..
  9. 9. Formulation Design  Review basic findings:  1) Sulphur X-links ………  2) Ionic X-links …….  ZnO gives maximum ………  3) Role played by KOH
  10. 10.  Latex Dipping Technology  iohn woon sung-liang  JW Latex Consultants (SA0052392-P)  http://latexconsultants.blogspot.com  Email: woonsungliang@yahoo.com.sg
  11. 11. THE DIPPING PROCESS 3 MAIN TYPES :- 1. STRAIGHT DIPPING (OR SIMPLE DIPPING) 0.03 – 0.04MM 2. COAGULANT DIPPING 0.1 – 1.0 MM 3. HEAT – SENSITIVE DIPPING 0.5 – 3.0MM
  12. 12. Properties of Good Antifoaming / Antiwebbing Agent 1. Surface tension of antiwebbing agent must be lower than that of foaming solution or liquid 2. Solubility of antiwebbing agent in foaming solution must be low enough but without causing cissing and oil spots. 5. It must be readily dispersible in the liquid 4. It must have high spreading coefficient
  13. 13. GLOVES FAULTS / DEFECTS By John Woon Sung-Liang http://latexconsultants.blogspot.com
  14. 14. FAULTS / DEFECTS AFFECTING LOCALISED WHOLE GLOVE
  15. 15. AFFECTING WHOLE GLOVE 1. THICKNESS 2. POWDER MARKS 3. COLOUR 4. FILM WEAKNESS (OCCLUSIONS ?) 5. TACKINESS 6. SURFACE BLEMISH (BLOOM?) 7. SMELL 8. TASTE 9. MOULDY *
  16. 16. LOCALISED DEFECTS 1. PIN HOLES 2. OCCLUSIONS 3. COAGULUM 4. RUNS OR STREAKS 5. THICK EXTREMITIES 6. CRACKS *
  17. 17. Polychloroprene Rubber (CR) John Woon Sung-Liang JW Latex Consultants (SA0052392-P) http://latexconsultants.blogspot.com
  18. 18. Polychloroprene Rubber (CR) - Properties  1) More polar than Butadiene due to  carbon-chlorine bond but not as polar as Nitrile rubber (medium and high acrylonitrile level)  2) Tg = - 45C  3) Moderate resistance to hydrocarbon oil (cf Nitrile rubber)  and good resistance to chemicals  4) Excellent resistance to Ozone (O3) degradation  5) Good adhesion to polar substrates  6) Flame resistance (Self-extinguishing) *
  19. 19. Compounding of Polychloprene Latex  A B C  Rubber 100 100 100  ZnO x y z  TMTD a - -  ZDEC b - -  S c d e  Thiocarbanilide - g h  DPG - - i  NaDBC - j -  A/O k l m
  20. 20. Typical physical properties of rubber film from soft version of CR (slower cure than hard version)  Film thickness (mm) 0.15  Tensile strength (MPa) 18.0  Modulus at 500% (Mpa) 1.5  Elongation at Break (%) 1000 *
  21. 21. TYPICAL PHYSICAL PROPERTIES OF PREVULCANISED DRIED FILMS GRADE A B C D 1.UNAGED Mod. at 700% 8.5 11.0 16.0 10.0  (MPa) T.S. (MPa) 28.0 28.0 26.0 28.0 Elongation at break (%) 1000 900 800 960 2.AGED (14 days @ 70 deg C)  Retention of Modulus  at 700% (% min) 50 75 85 75  Retention of T.S. 65 75 87 75  (% min)
  22. 22. COLLOIDAL PROPERTIES OF A TYPICAL COMMERCIAL BATCH OF PV  TSC % 60.46  ALKALINITY (Meq) 360  pH 10.45  VFA No 0.011  MST (sec) 1510  Magnesium (ppm) Nil  KOH No 0.59  Coagulum (ppm) 43 
  23. 23. Prevulcanised Latex vs Post-vulcanisable latex compound Vulcanisable Compound Post A B UNDERCURE OVERCURE X-LINK DENSITY /VISCOSITY Prevulcanised Compound 1 2 3 4 5 6 TIME (Days)

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