-----------------

JW Latex Consultants (and Rubber Consultants,乳胶顾问) offer solutions to your problems in Natural Rubber latex and Synthetic Rubber latex processing and the manufacturing of latex products (condoms, catheters, medical gloves, baby teats and soothers, toy balloons etc) Quick answers through e-mails are possible at reasonable cost.

__________________________________________________________________________

CONTENTS:

[Advantages of Prevulcanization] [Air Permeability] [Applications of PV Latex] [Bacteria and Latex] [Chemical Toxicity] [Cross-Linking Density] [Biodegradability] [Black Articles] [Blooming] [Bouncing Ball] [Compression Set] [Condoms] [Copper Staining] [Creaming] [Defoamer] [FDA] [Fatty Acid Soaps] [Flame Retardant] [Flocking] [Food Packaging] [Glove Demand] [Glove Discoloration] [Glove Selection] [Guayule Latex] [History of Gloves] [Joul Effect] [Lab Equipment] [“Latex” Definition] [Natural Rubber Latex Stability] [Natural Rubber Latex Thread] [Milling Problem] [Mixing Equipment Directory] [MREPC Articles] [Nano Polymer Particles] [Nano ZnO] [Permanent Set] [Polychloroprene] [REACH] [SMG] [Storage Hardening] [Stress Relaxation] [Surfactants Directory] [Tensile Properties] [Vulcanization] [Vytex] [Yulex]

__________________________

You Are Visitor Number:

counter
Expedia Promotional Codes

__________________________

This Site Is Best Viewed With Mozilla Firefox Browser. If You Are Viewing With Internet Explorer, It Is Advisable to Switch to Mozilla Firefox By Going to This Link -> http://www.mozilla.org/en-US/firefox/new/

It Is Free to Download

__________________________

Send Your Enquiry and Orders To: woonsungliang@yahoo.com.sg

Problem Solving Through E-Mails with John Woon Latex Consultants Is Possible
可以通过电子邮件与JW乳胶顾问来解决问题

__________________________

Please kindly donate to support the maintenance of this site. We'd appreciate it very much.

__________________________

__________________________________________________________________________

Tuesday, July 26, 2016

Effect of Cross-linking - A Very Important Aspect of Rubber Technology


Students: We have just started our training course on vulcanization and cross-linking of Natural Rubber. Can you please let us know in general the effect of cross-linking on the behavior of the vulcanized rubber?

John Woon (Senior Latex Consultant):
Please see the Table above for the "Changes in Rubber Properties with An Increase in Degree of Cross-Linking".


JWLatexConsultants.com Hacked and Infected!!



John Woon (Senior Latex Consultant): Please be informed that our sister website, JWLatexConsultants.com has been hacked and infected. Please do not visit this site for the time being. We apologize for any inconvenience caused.

Instead, please visit http://woonsungliang.wix.com/jw-latex-consultants

Monday, June 27, 2016

Sodium Soaps vs Potassium Soaps as Latex Stabilisers


Manufacturer: We use both KOH and NaOH for making our fatty acid soaps as  stabilizers for our latex compounds. We are experiencing more problem with sodium soaps especially when there is a change in ambient temperatures. Why?

John Woon (Senior Latex Consultant): Simple. The reasons are as follows:

1) Sodium soaps are less soluble than potassium soaps.
2) Sodium soaps are harder than potassium soaps.
3) Sodium soaps tend to gel at lower temperatures although this phenomenon is reversible.

Therefore from technical point of view, there is no reason why you should use sodium hydroxide although it might be cheaper than potassium hydroxide.


Monday, June 06, 2016

Blowing Agent (Foaming agent) for PVC Plastisol

Manufacturer: We are manufacturers of products based on PVC plastisols including PVC gloves. We are now venturing into making foamed products but our initial work has not been successful. We believe that this could be due the wrong choice of blowing agent as our processing temperature is quite low at about 120 C.  We would appreciate very much if you could suggest some suitable blowing agents for our use.



John Woon (Senior Latex Consultant): Some of the most common blowing agents used for rubber and plastic do have high decomposition temperatures of more than 150°C which would of course not work satisfactorily if your processing temperature is only 120°C.

I suggest you evaluate the following:

Azo nitriles, bezene sulphonic acid hydrazide and ditroso pentamethylene tetramine.

Let me know the outcome in due course.



Thursday, May 26, 2016

Wetting Agent in Coagulant

Manufacturer: We are in the process of improving the wetting property of our coagulant mix to overcome pinhole and thin spot problems. We would appreciate very much if you could advise us on the temperature, level of wetting agent, cloud point, etc.


John Woon (Senior Latex Consultant): You need to pay attention on the following factors:


1) Temperature of the coagulant should be as high as possible but not exceeding the could point or 65°C to achieve maximum wetting.

2) Level of wetting agent is to be high enough but not to the extent of causing foaming and retarding drying.

3) You should determine the could point on your own instead of just relying on surfactant suppliers' cloud points because salts such as calcium nitrate and other ingredients in the coagulant mix can affect the cloud point.

Details has been sent to you separately at your request.


Thursday, May 19, 2016

Reducing Ammonia Content of Latex Concentrate with Formaldehyde

Manufacturer: We are manufacturing dipped tubes, for medical in small scale.
Can we add formaldehyde to reduce the concentration of ammonia in high ammonia latex, so that even dip could be produced?
 
John Woon (Senior Latex Consultant): Yes, you can add formaldehyde to reduce the ammonia content in the latex.When you add formalin to the latex, pH would drop and latex would tend to destabilise. Therefore you need to add a non-ionic surfactant first. Stir for two hours before adding formalin.

You can try Emulvin W or equivalents as the surfactant. If you continue to encounter stability problem such as viscosity rise it could be due to the latex quality problem, in which case I suggest you remove the ammonia by stirring with a fan over the surface of the latex.
 

Thursday, April 21, 2016

Curatives for the Vulcanisation of Nitril Rubber

Manufacturer: We are manufacturing rubber parts using dry natural rubber (SMR) via compression molding and are about to conduct some trials using dry carboxylated nitrile rubber. We would be obliged if you could give us some guide lines in terms of curatives compounding.

John Woon (Senior Latex Consultant): For general applications, you can used practically the cure systems for both NR and SBR such as thiazoles and sulphenamide cure system. For high temperature applications and also where low compression set is required, both thiuram and peroxide cure systems should be used.

You should also get the advice from the rubber suppliers or manufactueres because the following factors involved in polymerization, etc. are also affecting the vulcanisation of nitrile rubber:

1) Coagulant
2) Emulsifiers and surfactants
3) Polymerization additives
4) Polymer rheology
5) Process aids in polymerization

Friday, April 08, 2016

Blending of Different Latices and Addition of Fillers in Latex Adhesive Compounds

Manufacturer: We are manufacturer of latex-based adhesives. Please give us some general guidance in blending of two different latices and the addition of fillers in terms of latex colloidal stability.

John Woon (Senior Latex Consultant): I suggest you look into the following points:

1) Blending of two different latices (latexes)

1.1) Make sure the pH of both latices are as close as possible. By changing the latex pH, the latex could sometimes be destabilized in which case, it is advisable to add a non-ionic surfactant to that latex before the pH adjustment.

1.2) Latex with smaller particle size would tend to rob the surfactant already present on the particles of latex with higher particle size. Generally, the level of surfactants required for the blend is more than the total amount required for the two individual latex.

2) Filler addition

2.1) You could either add the filler dry or as a pre-prepared slurry to the latex. The former would require higher level of surfactant than the latter.

2.2) The higher the level of filler, the higher is the level of surfactant required.

2.3) Filler with smaller particle size would tend to rob more of the surfactant from the latex particles compared to filler with coarser particles.

2.4) Filler type is important e.g. clay and talc would have less destabilizing effect on the latex compared to calcium carbonate.

2.5) Generally a combination of surfactants performs better than a single surfactant.

Hope this helps.


Tuesday, March 15, 2016

Mechanism of the Leaching Process

Manufacturer: I am the head of the R&D department in a latex dipped products manufacturing company in Sri Lanka. In order for me to understand the importance of leaching, I need to know the mechanism involved during leaching. Can you help?

John Woon (Senior Latex Consultant): Over the years I've studied and analyzed the factors involved in the leaching process so as to achieve the most optimized leaching effectiveness for a variety of dipped products.

I've identified 7 steps which take place in sequence during leaching. I've sent this along with some details of each step to you separately. Please let me know if this is of any help.



Working Off of Old Latex Compounds

Manufacturer: We are using different latex compound formulations for different products. This always results in the built-up of old latex compounds of more than a few weeks old. How can we make use of old latex compounds to minimise wastage?


John Woon (Senior Latex Consultant): Beware of possible problems when using old latex compounds especially when it has already “over-cured” as it would lead to low elongation at break, high modulus and poor tensile strength and hence premature tearing.

You could try to blend this off into new and fresh compound but lab experiments must be carried out to see if the physical properties (i.e. tensile strength, modulus and elongation at break) are acceptable for the ratios of the blending you've selected

Another alternative is to use prevulcanised latex which does not normally over cure on storage.


__________________________

What has the bouncing ball to do with tyres?

Latex Gloves Educational Articles from the Malaysian Rubber Export Promotion Council

How do you select your medical gloves?

Rubber Chemicals: Carcinogenicity, Mutagenicity, Clastogenicity.

Why is Compression Set measurement important?

Assessment of Latex Stability

Joule Effect

Poor Flocking Quality Of Household Gloves

Creaming of Latex

What is Vulcanization?

History of Latex Dipped Products

Applications of Prevulcanized Latex

Defoamer Creating Havoc in Glove Factory

Problems With Milling Rubber Chemicals

Medical Gloves From Guayule Latex

Introduction to SMG Gloves

 

 

Click on The Following Links to Read More Articles:

[Advantages of Vulcanization] [Applications of PV Latex] [Bacteria and Latex] [Chemical Toxicity] [Cross-Linking Density] [Biodegradability] [Black Articles] [Blooming] [Bouncing Ball] [Compression Set] [Condoms] [Creaming] [Defoamer] [FDA] [Fatty Acid Soaps] [Flame Retardant] [Flocking] [Food Packaging] [Glove Demand] [Glove Selection] [Guayule Latex] [History of Gloves] [Joul Effect] [Latex Stability] [Latex Thread] [Milling Problem] [MREPC Articles] [Nano Polymer Particles] [Nano ZnO] [Polychloroprene] [REACH] [SMG] [Storage Hardening] [Vulcanization] [Vytex] [Yulex]

Disclaimer:
The information and data contained in this site are believed to be accurate and reliable. However it is the responsibility of the visitors and readers to satisfy themselves that the information is workable under their own processing conditions. Hence the owners of this site make no warranties concerning the suitability of the information given in this site.

__________________________