Taking a closer look – SEM Pictures of FKM Crumb

After a bit of good old fashioned arm twisting, I managed to convince an old university friend to use some seriously expensive pieces of kit to peek into the fine detail of the pride of J Allcock and Son’s product line. I sent several samples of our Ambiently-ground FKM crumb, and a competitor’s Cryogenically-ground FKM Crumb to my mate Rob Hooley, studying for a PhD in Materials Science at the University of Leeds, who was kind enough to put them through a Scanning Electron Microscope (SEM) and produce some fantastic pictures.


Picture 1 (Left) & 2 (Right): Cryogenically ground FKM 30’s Mesh and Ambient Ground FKM 40’s Mesh

These two pictures above show the difference in surface structure between cryogenically and ambient ground FKM crumb. The Cryogenic material has been frozen and shattered, thus the particle morphology appears much more angular and sharp compared to the torn material, with extremely rough edges due to the physical tearing of the rubber. The coarser material should bond better into a new FKM compound, due to the much larger surface area exposed to the fresh compound, and the possible exposed polymer chains due to the tearing of the material. As cryogenic freezing causes the rubber to break along micro-fissures or micro-tears, the surface would have fewer areas available for bonding.

Picture 3 (Left) & 4 (Right): Cryogenically ground FKM 72’s Mesh and Ambient Ground FKM 72’s Mesh

The pictures above again show the two types of ground FKM, but this time the smaller 72’s Mesh size. The size of the 2 grains is very similar, which is to be expected, but again the coarseness of the ambient ground material can still be seen. The scale of the peaks and troughs are not as extreme, but as this is a smaller grain, the increase in ‘bond-able’ surface area is not to be sniffed at. We at J Allcock and Sons believe (and have done many trials that prove our belief) that our ambient ground 72’s mesh FKM binds better than our 40’s mesh FKM crumb. 72’s mesh crumb can therefore be used at higher concentrations in newly made FKM compound, therefore saving you even more on compound cost.

Picture 5 (Left) and 6 (Right).  5 Shows Ambient ground FKM 72 mesh, using ‘LU’ settings, while 6 shows the same material, at the same resolution using ‘NM’ settings.

The ‘LU’ (seen at the base of this picture) indicates a technique that focuses on showing the topography of the sample using secondary electron imaging. SE imaging (SEI) involves electrons produced by ionisation induced by the incoming electron beam. These electrons are very low energy, and as such are very sensitive to the surface structure, this allows for the surface of the sample to be resolved in great detail, even showing the 3 dimensional structure of individual crumb.

Meanwhile, the ‘NM’ (again at the base of the picture) indicates Backscattered electron imaging (BSE), where electrons hit the sample with great energy, allowing them to penetrate the surface and interact with the bulk of the material. This results in the electrons bouncing around the material before being released. The energy they leave the material with is directly proportional to the mass of the atoms they interact with, much like how sound waves are absorbed by a carpeted floor, but bounce off a marble floor. Therefore, the light specks seen in the photo are heavier parts of the rubber compound, mainly Oxides of Magnesium, Calcium and Silicon (Thanks again to some further elemental analysis by Rob Hooley) as the heavier elements reflect more electrons and thus create a brighter image.

Pictures 5 and 6 therefore show the same sample of 72’s Mesh FKM using two types of imaging technique. Picture 5 (like the previous images) shows the surface contours of the FKM crumb, again showing the coarser nature of our material, which is ideal for binding into the compound matrix. Picture 6, however, reveals some of the components of the FKM compound as well as giving a different angle on the depth of some of the troughs and the quality of the FKM compound itself (nice even spread of a moderate amount of fillers can be seen in the crumb itself).

Picture 7 (Top left) and 8 (Top right). 7 shows cryogenically ground 72 Mesh FKM Crumb using LU (SEI) Settings, while 8 shows the same material under NM (BSE) Settings. Pictures 9 (bottom left) and picture 10 (bottom right) show ambient ground 72’s mesh FKM at the limits of the SEM’s resolution, again using ‘LU’ and ‘NM’ techniques respectively

These final images push the resolution of this electron microscope to its limits, with a scale of 10 microns seen in the bottom right hand corners of the lower two images. At such a large magnification, the difference in the surfaces of the crumb is more subtle. The main difference that can be seen would be the exposure of the filler. Picture 8 shows the filler underneath the surface, while picture 10 shows the exposed filler at the surface. We believe that the exposed filler will create an increasingly jagged surface, helping bonding into the compound at a smaller scale.

I hope you’ve enjoyed the pictures, and how microscopic differences in FKM crumb can have a large effect on the resultant compound.

Thanks again for the Fantastic Pictures, and some much needed advice on some of the more technical sections of this post to Rob Hooley, Here’s to our next pint in 2016!

Sehr gute zeit in Nürnberg!

After a busy few weeks, thanks to the tremendous interest generated by our stand at DKT, We’re happy to say that our venture to the European Technical Rubber Convention was a great success!

Highlighting the use of Rubber crumb and Granule in rubber compounds, without the loss of properties, Our unique FKM crumbing facility and the extremely small particle size we can generate was received with great interest. We were able to show, first hand, how fine our FKM powder can be made, thus increasing the amount you can add into your compounds and saving you considerable costs without any deterioration of FKM properties.

We’d like to extend a big thank you to everyone who can to visit our stand and we hope to continue providing technical knowledge and top quality products to all our clientele.

Review of the Year – 2014 @ J Allcock and Sons

2014 at J Allcock and Sons Ltd.

It’s been another great year here at J Allcock and Sons. Rubber crumb and granule sales are up on last year, with an additional granulator to be installed next year and upgrading the line at our Wellington Rubber branch. FKM crumb production has increased 20% from last year and looks set to continue to increase into the New Year. In addition to our stringent particle size laboratory testing, we have recently instigated a quick pass/fail test during production, at short regular intervals. This will maintain the quality of our material that we’re known for.

Silicone sales are also up from last year, especially our Food Grade Silicone Emulsions. Of the small number of complaints to the company, most of them were due to poor housekeeping by the end user leading to silicone splitting (for tips on how to stop this, have a look at our previous blog post ‘A Splitting Headache’).

With this sustained increase in sales, we’re also looking into expanding our storage facilities, expanding our storage capacity by tens of tonnes.

Finally, we’ve welcomed 2 new members to the company. I joined just before Luke departed for a year in Australia, and Stephen has joined to learn the ropes controlling stock and purchases.

Looking to the New Year, we expect to continue our personalised service for our clients and welcome new clients from both the UK and the continent, thanks to our upcoming foreign language translations of our website. We’ll also be at DKT (Deutsche Kautschuk-Tagung) 2015 in Nuremburg in the summer to show our crumb and rubber reclaim to the European Rubber Community.

We’d like to say a big thank you to all our clients for continuing to choose us as there supplier, and the staff at J Allcock and Sons for a great year. We wish you all a merry Christmas and a happy 2015!

Matt Darlington

Red/Brown & Green FKM Crumb Available

Red/Brown and Green FKM Crumb

Red/Brown and Green FKM Crumb

J. Allcock & Sons’ now have the ability to provide an extra 11 tonnes of Red/Brown FKM Crumb and 4 tonnes of Green FKM crumb per month.

Cured FKM scrap is sent to our facilities on a monthly basis and we granulate and “crumb” this FKM scrap to  72′s and 120′s mesh particle size. These particle sizes are not averages, so when we say 120′s Green FKM Crumb, we mean the biggest particle you will find will be 120′s mesh!

We always ask the customers we visit: What’s the cost of testing FKM Crumb in your compound? Compare that amount, to the amount you will be saving if tests came back positive and you started using it…

If you are interested in trialling some of the above crumb, please contact us at ja@allcocks.co.uk or +44 (0) 1612237181.

Alternatively, if you are unsure about using a different FKM compounded crumb in your own FKM compound, why not speak to us about “crumbing” some of your scrap and J. Allcock & Sons’ sending it back to you?

Carnauba Wax

I haven’t written a technical blog recently, so I have decided that I should write one regarding Carnauba wax. We have high stocks of Type 3 Carnauba wax, in powder form, so perhaps it might bring us some new sales!

With the help of Norman Challinor, here is some information on Carnauba wax!

Carnuaba wax is also known as Brazil wax and Palm wax. It is a hard wax obtained from the leaves of the palm copernicia prunifera - a plant native to and only grown in north eastern Brazil.

It is usually in the form of hard yellow / brown flakes that can also be ground down to a fine powder and often offered in that alternative form.

Due to its fantastic properties compared to other waxes, most people believe it is one of the best waxes in the world; hence it is sometimes referred to as the “queen of waxes.”

It has a melting point of 80 – 86 oc and a density of about 0.97

The main components are:-

Aliphatic esters                                                   (40% by wt.)
Di-esters of 4 – hydroxycinnamic acid                (21% by wt.)
ω – hydroxycarboxylic acids                               (13% by wt.)
Fatty acid alcohols                                              (12% by wt.)

Predominantly derived from acids and alcohols in the c26 – c30  range.

Carnauba wax, can come in Type 1, Type 3 and Type 4. These “types” relate to the purifity level, with Type 1 being most pure and Type 4 being least.

It has a very wide range of uses, including …..

  • Polishes (Usually Type 4 used)
  • Food (chewing gum, gravy, sauces, sweets etc) (Usually Type 1 used)
  • Pharmaceutical (tablet coating agent)  (Usually Type 1 used)
  • Cosmetic (Usually Type 1 used)
  • And of course, as a process aid and mill / mould release agent in rubber compounds, particularly the harder to process specialist materials. (Usually Type 3 used)

For rubber compounders:

In rubbers, the hard nature of the material will not act as a softener but will behave as an internal lubricant, facilitating the incorporation and dispersion of the non-rubber ingredients.

Its relatively low melting point means that it will migrate to the surface of the rubber and form an extra, very thin, layer between the rubber surface and the metal it is in contact with – - i.e. The mill bowls or the mould surface.  The hardness of the wax means that it will not act as a sticky softener, but will form a release layer, overcoming the tendency for the rubber to stick to the metal.

Allcocks mostly sell, Type 3 Powder, and we really focus on selling to the high specification rubber compounding industry, such as FKM compounds.

Here is some technical information on our T3 Carnauba Wax Powder:

Solubility                                      Insoluble in water; partially soluble in Alcohol.
.                                                   Soluble on warming in Ethyl Acetate & Xylene.
Melting Point                               80-86°C
Acid Value                                   2-7 mg KOH/g
Sponification Value                     78-95 mg KOH/g
Ester Value                                 71-93 mg KOH/g
Sulphated ash                             No more than 0.25% w/w
Unsaponifiable matter                 50-55 μm
Particle Size                                100%  passing 600 μm
.                                                   94.8% passing 300 μm
                                                  88.1% passing 250 μm
                                                  40.6% passing 125 μm

If you have any questions regarding carnauba wax, please feel free to email ja@allcocks.co.uk! Despite only selling T3 Carnauba Wax powder, please feel free to get in touch regarding other types, we may be able to help.