Examples of Examples of TrainingTraining
Slides Used by Slides Used by John Woon Latex John Woon Latex
ConsultantsConsultants
NR LATEX PROPERTIESNR LATEX PROPERTIES(Hevea Brasiliensis)(Hevea Brasiliensis)
John Woon Sung-LiangJohn Woon Sung-Liang
JW Latex ConsultantsJW Latex Consultantshttp://latexconsultants.blogsphttp://latexconsultants.blogsp
ot.comot.com
NR LATEX PROPERTIES NR LATEX PROPERTIES (Hevea Brasiliensis)(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
STABILITY OF LATEXSTABILITY OF LATEXJohn 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
SOAP IN PRESENCE OF NH 3)
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-
RH/C RH/C
What is What is Nitrile Nitrile oror Buna-N Buna-N oror NBRNBR RubberRubber??
By John Woon Sung-LiangBy John Woon Sung-Liang JW Latex ConsultantsJW Latex Consultants (SA0052392P)(SA0052392P) http://latexconsultants.blogspot.comhttp://latexconsultants.blogspot.com Email: Email:
[email protected]@yahoo.com.sg
WHY Use NBR?WHY Use NBR?
Mainly because of the presence Mainly because of the presence of Acrylonitrileof Acrylonitrile
Acrylonitrile content can be: Acrylonitrile content can be: Low (Low (25%) 25%) Medium (33%) and Medium (33%) and High (45%) *High (45%) *
Acrylonitrile vs Tg Acrylonitrile vs Tg (Tg = -10C to -55C)(Tg = -10C to -55C)
-10-10
-20-20
-30-30
- 40- 40 TgTg(Degree C)(Degree C) -50-50
-60-60
10 20 30 40 50 6010 20 30 40 50 60 Acrylonitrile level (%)Acrylonitrile level (%)
Main Differences in Main Differences in Processing Compared with Processing Compared with
NRNR 1) pH adjustment1) pH adjustment
- Sensitive ……...- Sensitive ……...
- If below 9.0 …………- If below 9.0 …………
- If above 9.8 …………- If above 9.8 …………
Alkali must be added ………..Alkali must be added ………..
Formulation DesignFormulation Design
Review basic findings:Review basic findings:
1) Sulphur X-links ………1) Sulphur X-links ………
2) Ionic X-links …….2) Ionic X-links ……. ZnO gives maximum ………ZnO gives maximum ………
3) Role played by KOH3) Role played by KOH
Latex Dipping Latex Dipping TechnologyTechnology
iohn woon sung-liangiohn woon sung-liang JW Latex Consultants JW Latex Consultants (SA0052392-P)(SA0052392-P)
http://latexconsultants.blogspot.comhttp://latexconsultants.blogspot.com Email: [email protected]: [email protected]
THE DIPPING PROCESSTHE DIPPING PROCESS
3 MAIN TYPES3 MAIN TYPES :- :-
1.1. STRAIGHT DIPPINGSTRAIGHT DIPPING(OR SIMPLE DIPPING)(OR SIMPLE DIPPING)0.03 – 0.04MM0.03 – 0.04MM
2.2. COAGULANT DIPPINGCOAGULANT DIPPING0.1 – 1.0 MM0.1 – 1.0 MM
3.3. HEAT – SENSITIVE DIPPINGHEAT – SENSITIVE DIPPING0.5 – 3.0MM0.5 – 3.0MM
Properties of Good Antifoaming /Properties of Good Antifoaming /Antiwebbing AgentAntiwebbing Agent
1.1. Surface tension of antiwebbing agent Surface tension of antiwebbing agent must be lower than that of foaming must be lower than that of foaming solution or liquidsolution or liquid
2.2. Solubility of antiwebbing agent in foaming Solubility of antiwebbing agent in foaming solution must be low enough but without solution must be low enough but without causing cissing and oil spots.causing cissing and oil spots.
3.3. It must be readily dispersible in the liquidIt must be readily dispersible in the liquid
4.4. It must have high spreading coefficientIt must have high spreading coefficient
GLOVES FAULTS / GLOVES FAULTS / DEFECTSDEFECTS
By John Woon Sung-LiangBy John Woon Sung-Lianghttp://latexconsultants.blogspot.comhttp://latexconsultants.blogspot.com
FAULTS / DEFECTSFAULTS / DEFECTS
AFFECTINGAFFECTINGWHOLE GLOVEWHOLE GLOVE
LOCALISEDLOCALISED
AFFECTING WHOLE GLOVEAFFECTING WHOLE GLOVE
1.1. THICKNESSTHICKNESS
2.2. POWDER MARKSPOWDER MARKS
3.3. COLOURCOLOUR
4.4. FILM WEAKNESS (OCCLUSIONS ?)FILM WEAKNESS (OCCLUSIONS ?)
5.5. TACKINESSTACKINESS
6.6. SURFACE BLEMISH (BLOOM?)SURFACE BLEMISH (BLOOM?)
7.7. SMELLSMELL
8.8. TASTETASTE
9.9. MOULDYMOULDY **
LOCALISED DEFECTSLOCALISED DEFECTS
1.1. PIN HOLESPIN HOLES
2.2. OCCLUSIONSOCCLUSIONS
3.3. COAGULUMCOAGULUM
4.4. RUNS OR STREAKSRUNS OR STREAKS
5.5. THICK EXTREMITIESTHICK EXTREMITIES
6.6. CRACKS *CRACKS *
Polychloroprene Polychloroprene Rubber (CR) Rubber (CR)
John WoonJohn Woon Sung-LiangSung-Liang
JW Latex ConsultantsJW Latex Consultants (SA0052392-(SA0052392-P)P)
http://latexconsultants.blogspot.cohttp://latexconsultants.blogspot.comm
Polychloroprene Rubber Polychloroprene Rubber (CR)(CR)
- Properties- Properties 1) More polar than Butadiene due to 1) More polar than Butadiene due to carbon-chlorine bond but not as polar as Nitrile carbon-chlorine bond but not as polar as Nitrile
rubber (medium and high acrylonitrile level)rubber (medium and high acrylonitrile level)
2) Tg = - 45C2) Tg = - 45C
3) Moderate resistance to hydrocarbon oil (cf Nitrile 3) Moderate resistance to hydrocarbon oil (cf Nitrile rubber)rubber)
and good resistance to chemicalsand good resistance to chemicals
4) Excellent resistance to Ozone (O3) degradation4) Excellent resistance to Ozone (O3) degradation
5) Good adhesion to polar substrates5) Good adhesion to polar substrates
6) Flame resistance (Self-extinguishing) *6) Flame resistance (Self-extinguishing) *
Compounding of Compounding of Polychloprene LatexPolychloprene Latex
AA BB CC Rubber Rubber 100 100 100100 100 100 ZnO xZnO x y z y z TMTD TMTD a - -a - - ZDEC bZDEC b - - - - S S c d ec d e Thiocarbanilide Thiocarbanilide - g h- g h DPG DPG - - i- - i NaDBC NaDBC - j - - j -
A/O kA/O k l m l m
Typical physical properties of rubber Typical physical properties of rubber filmfilm
from soft version of CR (slower cure from soft version of CR (slower cure than hard version)than hard version)
Film thickness (mm) 0.15Film thickness (mm) 0.15
Tensile strength (MPa) 18.0Tensile strength (MPa) 18.0
Modulus at 500% (Mpa) 1.5Modulus at 500% (Mpa) 1.5
Elongation at Break (%) 1000 Elongation at Break (%) 1000 **
TYPICAL PHYSICAL PROPERTIES OF TYPICAL PHYSICAL PROPERTIES OF PPREVULCANISED DRIED FILMSREVULCANISED DRIED FILMS
GRADE A B C D1.UNAGEDMod. 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)
COLLOIDAL PROPERTIES OF A COLLOIDAL PROPERTIES OF A TYPICAL COMMERCIAL BATCH OF TYPICAL COMMERCIAL BATCH OF
PVPV 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
Prevulcanised Latex vs Prevulcanised Latex vs Post-vulcanisable latex Post-vulcanisable latex
compoundcompound
TIME (Days)
X-LINK DENSITY/VISCOSITY
Post Vulcanisable Compound
Prevulcanised Compound
1 2 3 4 5 6
A B
UNDERCURE OVERCURE
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