Last updated 8 August 01

Musing With Sin – Year 2001

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[Musing With Sin – Year 2000, Item 1-75]

“Beauty without grace is like a bait without a fish” – Emerson

A main-bar kaki of mine recently commented that Asians are generally not high on the score with respect to “graciousness”. This came after the Penang State annual awards. Rather than congratulate and address our new Datuks, we tend still to call them by their nick-names.

Sin Rubtech™ is a vendor of polymer bound predispersed chemicals. Under ISO 9000 requirements, bless ISO, our users need to audit us on a periodic basis. Everybody needs some form of encouragement to strive for continuous improvement and excellence. We are very pleased and encouraged by some of these ISO audit reports, two of which are reproduced here.

110. Soft-Feel Elastomeric Products

We are familiar with soft toys made of microcellular/ sponge formulations. However solid elastomeric products of Shore A < 30 are not easy to formulate and process as people like K.S.Lim (Kossan) and I can well appreciate years back trying to make oil-resistant NBR printer rollers.

It was therefore quite refreshing to listen to a paper by S.M.Leong & Sam Angove at the PRIM AGM Seminar 28^th July 2001 pointing out that TPE manufacturers like GLS Corporation can now offer “extremely soft” easy to process thermoplastic elastomers Dynaflex^® TPE’s with Shore A < 10 and they have products to prove it. Examples are:

Gillette^® Mach 3 Triple Blade Razor

Questech “Too Hot™” Infant Feeding Spoon

Mattel toys

Etc.

Again the oft repeated advice:

“Find A Niche Market Need, Go And Fill It”

109. Rubbers, Elastomers, Thermoplastic Elastomers, Thermoplastic Olefins, Thermoplastic Vulcanisates and Melt Processable Rubbers.

Life is getting more confusing to this senior rubber man brought up amongst Hevea brasiliensis trees. In the old days a rubbery material like NR means that the rubber vulcanisate can be stretched to about 3X its length and upon release of its stress, it will rapidly return to its original length. The NR vulcanisate can behave rubbery even when tested at sub-zero or up to 170^OC. We can accept the rubbery behaviour of some 15 classes of synthetic rubbers. Then the plastic boys got into the act with initially thermoplastic elastomers that can exhibit rubbery behaviour at room temperature and up to about 70^OC service temperature. They can’t really call these materials thermoplastic rubbers, elastomers are more acceptable, as they are not really rubbery materials. However today there are thermoplastic elastomers with service temperatures of ~170^OC and polymer chemists have combined rubber and plastic monomers/ polymers using various processes and tweaked them to suit various applications. We have a vast array of such thermoplastic elastomers today with so many combinations that I think they are running out of abbreviations and some of these can behave differently depending on their manufacturing process and hence trade-names are often necessary to differentiate them. Readers are alerted to some of these relatively new thermoplastic elastomers which are making rapid in-roads into traditional rubbery niche markets.

	Abbrev.	Tradename	Company
Thermoplastic Elastomers (TPE)	SBS SEBS SEP SEB	Kraton* Steoron Europrene	Shell Firestone Eurochem
	* Now sold to Ripplewood Holdings USA

Thermoplastic Polyolefin Elastomers (TPO)	--- POP POE	Cattalog^® Affinity^® Attane Engage^®	Montell Dow Dupont

Thermoplastic Polyurethane Elastomers (TPU)	TEEE	Elastollan^® Pellethane^® Bayflex^® Texin^® Morthane^® Hytrel^® Riteflex^® Arnitel^®	BASF Dow Bayer Bayer Morton Dupont Ticana DSM

Thermoplastic Polyamide Elastomers (TPE)	PEBA	Pebax^®	Elf Atochem
Melt Processable Rubber (MPR)		Acrylyn^®	Advanced Polymer Alloys

Thermoplastic Vulcanisate Elastomers (TPV)		Santoprene^® Geolast^® Trefsin^®	AES AEI AES

All above have been developed for niche commercial markets. I hope NR chemists can do more of tweaking NR-based grades for the speciality thermoplastic elastomeric markets rather to be content at its present low price as the single largest market share elastomer and the oldest general purpose elastomer.

Abbreviations Used

SBS - Styrene butadiene

SEBS - Styrene ethylene/ butylene styrene

SEP - Styrene ethylene propylene

SEB - Styrene ethylene butylene

POP - Polyolefin Plastomers

POE - Polyolefin Elastomers

TEEE - Thermoplastic etherester elastomers

PEBA - Polyether block amides

108. Mullin’s Effect, Payne Effect, Joule Effect etc.

Whenever we tried to explain the importance of good dispersion and distribution of curatives in any formulation, we are invariably drawn to comparative examples of carbon blacks and silicas more familiar to rubber technicians and which can help us to explain the equal importance of good dispersion/ distribution of curatives. Rubber technicians can readily accept that the full effect of a reinforcing filler can only be realised if its surface is thoroughly wetted by the polymer in which it is dispersed and distributed. For example in a poorly dispersed tread formulations, rubber technicians can see lower tensile strength, higher Akron Abrasion loss and Goodrich Heat Build-Up (HBU).

Considerable R&D work has been done over the past 50 years on the dynamic properties of rubber and there are theories that can explain the effects of reinforcing fillers and their wetting etc. on dynamic properties. Some of the terms used are not so familiar with younger rubber technicians.

Most of us should be familiar with the “Mullin’s Effects” first published in 1950¹. this refers to stress softening of gum or filled vulcanisates, (Fig.1). When rubber vulcanisates are stretched and then allowed to retract subsequent extensions to the same strain require a lower force. This is more pronounced in carbon black or silica filled vulcanisates than gum vulcanisates.

The dynamic properties of filled vulcanisates are more difficult to unravel and in the late 1970’s, Medalia’s² review of past R&D work especially his explanation of the contributions to the dynamic complex modulus G^* versus strain has stood the test of time.

We can all accept that polymer network i.e. cross-linked polymeric structure contributes to G^*, the higher the cross-link density the higher G^* and this independent of strain.

The “hydrodynamic or hydrodynamic-occlusion effect” is due to dilution of the rubber by the filler particles. If the filler particles are perfectly spherical such as glass beads or lamp blacks, then the resulting increase in elastic modulus is partially accounted for by Einstein’s equation:

E = E_o(1+1.25C+14.1C²);

where

E = modulus of filled elastomer

E_o = modulus of gum elastomer

C = volume fraction of filler

However highly structured carbon blacks such as N110, N121, N220, N234, etc. and precipitated silicas produced modulii larger than predicted by Einstein’s equation. This increase is partially due to rubber filling of the voids in the carbon black/ silica structures. The rubber occluded in these voids is shielded from any imposed deformation/ strain with the net result that the total rubber volume available for deformation is reduced i.e. as if volume fraction of filler is increased in formulation. This occlusion together with the dilution effect predicted from the Einstein equation means an increase in elastic modulus.

The “Paynes Effect” has only been introduced in recent publications. This refers to stress softening of filler vulcanisates at small deformations as example in the flexing of an automobile tyre. In 1971, Payne³ first studied the variation in dynamic modulus G^* with strain amplitude in phenyl-b-naphthylamine (PBN) loaded natural rubber which can form a crystalline network with the rubber, and he noted that both the low amplitude G^* and variation of G^* with amplitude closely resembled those of carbon blacks. Payne postulated then that the carbon black filler structure disrupted or broken by strain can explain both high modulii at low strain and the decline in modulus as the strain increases. Over the years this was confirmed by various researchers now with more sophisticated instrumentations like the RPA or MDR2000 to elucidate for example the “Payne Effect” (filler- filler interaction) as well as silica-silane coupling to the polymer main chain or the so-called “In-Rubber Structure⁴” (polymer-filler interaction) this being independent of strain.

Text Box: Source of Heat Energy The “Joule Effect” was discovered in 1859⁵. Joule noted that if a vulcanised rubber strip was fixed to a support at one end and was elongated by suspending weight at its other end, a sudden introduction of surface heat to the rubber sample caused the sample to retract. This thermal phenomena is called the “Joule Effect”. Wiegand W.B in 1925 made his Wiegand Pendulum which demonstrates so dramatically the Joule Effect and to students of thermodynamics, an almost perpetual machine if your ignore the heat source.

References

1.	Mullins, L	(1950)	:	J.Phys.Chem. 54, 239
2.	Payne, A.R & Whittaker, R.E.	(1971)	:	Low strain dynamic properties of filled rubbers. Rubb.Chem.Technol. 44, 440
3.	Medalia, A.I.	(1978)	:	Rubber Chem. and Technol., 51, p. 437
4.	Frolich, J. & Luginsland, H.D.	(2001)	:	RPA – Studies into the silica/ silane system. Rubber World, Vol. 224, No. 1 April.
5.	Dr. Jean Le Bras	(1957)	:	Rubber – Fundamentals of its science and technology – p. 96-97

107. Hardness Meter – Digitised

We are familiar with bench-top as well as portable durometers used to measure rubber hardness and specified in ASTM D2240, D531 and D1415. Because of tradition we are very familiar with durometers from Shore Instrument & Manufacturing Co., examples Shore A for normal rubbers, Shore D for hard rubbers and Shore C for soft rubbers and sponge/ microcellular products. It has recently been pointed out that durometers made from non-Shore companies should not be called Shore A but rather Durometer A or their proprietary names. Digital durometers like the Instron SI are a boon to laboratories fanatic on traceable results and not subject to the rubber technician’s sometimes off-day’s written records.

106. Sin Rubtech™ Testing Equipment

We have a comprehensive range to offer at very affordable prices.

The MDR2000DG rotor-less rheometer pictured here illustrates.

Indicative Prices:

Computerised Rheometer MDR2000DG: FOB USD14,500

Computerised Mooney Viscometer: MN200DG: FOB USD12,500

The MN200DG can be viewed at our laboratory.

105. High-Tech Shoes

We know that polymers are getting a lot of publicity in new automotive uses, medical products and even Nobel winning R&D wok on Polymeric LED TV/ PC screens (Items 74 & 79). I am glad that my interest in high-tech athletic shoes (Item 94) is also shared by Lev Grossman “Living Digital” Time, June 18, 2001, which illustrated 9 shoes ranging from the Velcro-free and lace-free Nike Air Resto Faze ultimate running shoe to Reebok’s Start Train DMX fitness shoe featuring a built-in computer chip with speedometer, odometer and calorie counter and the Street Flyers skating shoes with retractable wheels.

Who says the rubber industry is a sunset industry? In this E-Economy & K-Economy, Reebok has made a fitness shoe digital.

104. Foam Science is a Gas

Having just completed our Technical Bulletin #14 on the Art & Science of microcellular rubber products manufacture, I was rather tickled that a Sidney Perkowitz* actually wrote about - Universal Foams – anything with foams, froth and bubbles ranging from ice creams, foam mattresses and could possibly extend to our dear Dr. Jaspar’s famous soft naans (that go with his Tandoori Chickens next to our watering hole) with his secret blowing agent. Apparently we gather that we still can’t nail down exactly how and why a liquid foam structure behaves as they do. The rubber industry is not alone – in many other fields art has preceded science. *Publd by Vintage UK. ISBN: 0-099-28656

103. Amine Silane Cure System for Epoxidised NR (ENR)

The use of 3-aminopropyltriethoxysilane (OSI A1100) (See our Short Notes #5) with a catalyst such as an aromatic dihydroxy compound Bisphenol A, the 4,4’ isopropylidene bisphenol, in a joint paper by Dr. Azanam S Hashim – USM* caught my attention. Readers are aware that most ENRs are sulphur cured. The amino silane cure is through epoxy group ring opening. The rather long cure time ~ 30’/180^OC needed may limit the commercial exploitation of this cure system.

* Azanam, S. H et al (1995) : Silica Reinforcement of Epoxidised Natural Rubber by the Sol-Gel Method. Journal of Sol-Gel Science and Technology, 5, 211-218.

102. Grubbs’ Catalyst: A Vulcanising Agent

We are familiar with the use of the unsaturated diene: dicyclopentadiene (DCPD) used in EPDM to make it sulphur curable. A group of scientists at University of Illinois has mixed in microcapsules of DCPD in their epoxy compounds containing a ruthenium alkylidene catalyst known as Grubbs’ catalyst such that as the epoxy surface cracks, the stress breaks the DCPD capsules which are then crosslinked in minutes at ambient temperatures when in contact with Grubbs’ catalyst – thus self-repairing the epoxy material. A possible RTV repair putty!

Ref: Chemistry in Britain. April 2001: Polymers that heal naturally.

101. Made-in-Malaysia Dehumidifiers

Having just talked about molecular sieve desiccants (Item 93), I was pleasantly surprised to learn that there is a factory Bry-Air Malaysia in Bangi, Selangor already manufacturing/ assembling dehumidifying dryers, desiccant dehumidifiers, heat recovery systems, energy saving ventilators, treated fresh-air units and the latest product, a rotor-based mould dehumidifying system to eliminate mould sweating, a big problem in injection/ blow moulding machineries.

100. Centennial

A “centum” (latin) always invoke something special. Companies which survived 100 years history are revered. Presidents and Prime Ministers are assessed after only 100 days in office.

The 100^th item in our “Musing With Sin” is reached after 1½ years or 548 days after the launching of our website on 1^st Jan 2000 and after 2486 hits. What are my thoughts? Have I met the objectives set out in my “Introduction”? I would like to take this occasion to crystallise some thoughts from our previous 99 Items.

· Albert Einstein “ If A is a success in life, then A equals X-Plus-Y-Plus-Z. Work is X; Y is play; and Z is keeping your mouth shut”

I certainly am not one to agree on the Z component. Communications are vital to success

· Communications – IT, E-Economy & K-Economy

I still believe in Ralph Larsen famous saying in Item 63:

“ All the successes you see come because of strong business-line ownership, not IT ownership. Business-line ownership with strong IT support.”

However this may mean different things to different persons. Believe me, a lot of people are very confused when learned writers try to compartmentise things under E-Economy, K-Economy or dot.com companies. Even Ralph Larsen’s saying is not strictly correct as I know of no IT ownership which does not have business-line objectives. What Ralph Larsen implies is that IT + Production (P) Economy has a better chance of success as evidenced by his own Johnson & Johnson, Baxter etc. selling their products On-Line to American hospitals. This brings is to knowledge-driven or K-Economy. It is naïve to think that companies like Johnson & Johnson etc. with strong R&D, creativity, innovations, intellectual properties etc. cannot adopt IT and E-Economy themselves to enhance their productivity/ efficiency.

IT and E-Economy simply means that we now have the means to gather, store, analyse, retrieve and communicate information at the speed of electrons. Whether it is in the service or production sector, it means enhancement of productivity/ efficiency. The present USA leadership as the No. 1 economic power is a window to the power of IT & E-Economy in enhancing their competitiveness through productivity/ efficiency enhancements.

I can illustrate one Sin Rubtech example. I came back from an ASEAN country with an ultramarine blue masterbatch suspect problem. Took us 2 days to do the lab work, an hour to write up the report, 5 seconds to take a picture of the colour sample with our digital camera and seconds to send these through the Internet/ email to my customer. This would have not been possible without IT + E-Economy. However having IT + E-Economy, but you cannot solve the problem means zero, hence K-Economy comes into play.

· Productivity/ Efficiency Enhancement

I have lamented in Item 82 that it is no easy task trying to sell Product X which can reduce bottom-line costing by productivity/ efficiency enhancement. Fortunately we have many successes with our polymer bound predispersed chemicals. (PBPCs)

We have assisted a retread compounder to enhance their productivity by 100%. Same goes for many footwear factories (Items 83, 87 & 94). We have already reduced rejects or enhanced efficiencies in a transfer moulding operations by switching over to our PBPC curatives, compounders switching over to our polymer bound PEPTSIN S, compounders with poor insoluble S dispersion problems especially in polar + non-polar elastomeric blends (Item 31), enhanced efficiencies in using our PBPC form curatives, blowing agent, ZnO and TiO2 (Items 59 & 89) in microcellular products manufacture and many other examples.

What all this means is that PBPCs is a Sustainable 21^st Century Technology.

Finally, this Centennial has given Sin Rubtech much satisfaction and we wish our valued customers and potential customers the same.

I look forward to our “Millennial” or 1000^th Item.

99. Peroxides

Rubber technicians in NR producing countries are paying more attention to synthetics and the use of peroxide cure systems. Now peroxides have jaw-breaking chemical names and surprisingly manufacturers in the past have only coined the abbreviation, DCP, for dicumyl peroxide and we can easily identify Vanderbilts’ Varox DCP-40 MB, Sin Rubtech™ DCP-40G and Hercules Di-Cup T & Di Cup R. For others it is tough to convince purchasers that Akzo’s Trigonox 17-40 Bpd can be replaced by Vanderbilts’ Varox 230XL. It is refreshing to find that Laporte Speciality Organics Division (Degussa has recently taken over UK-based Laporte) Product Selector Issue 2 August 1999 has given abbreviations for all their organic peroxides. We do not agree that their DCup abbreviation should be used for DCP. Anyway, we have revised our Short Notes #11 with abbreviations for all the peroxides cited. It is timely the industry comes to terms on abbreviations for peroxides.

98. High Cis 1,4 Polybutadiene: Sin Rubtech™ BR9000

Yes, Sin Rubtech™ is also involved in synthetic rubbers, rubber machineries and test equipment besides polymer bound predispersed chemicals. High Cis 1,4 Polybutadiene rubbers (BR) were first introduced in the late 1950’s using Ziegler-Natta (Z.N.) type catalysts. Today high Cis BR’s ( > 90% Cis 1,4) are offered by several companies. The better known ones are:

Producer	Trade Name	% Cis	Catalyst Type
Bayer	Buna CB22 Buna CB 11 Taktene 1203	97 92 96	Nd Ti Co
JSR	JSR	~ 96	Ni
Nippon Zeon	Nipol	~ 96	Co
Kumho	Kosyn	96	Ni
TSR	Taipol	~ 96	Co
UBE	Ubepol	~ 98	Nd
Enichem	Europene Cis Neocis	92 98	Ti Nd

Goodyear	Budene 1208	98	Co
ASR	Cisdene	High	ZN
BYPC	Yanshan BR9000	96	Ni

Our BR9000 is a solution polymerised Cis 1,4 Polybutadiene using an aliphatic solvent (paraffins) and a carboxylic nickel (Ni), alkyl aluminium (Al), boron halide ether complex and a polar chemical compound. The rubber is almost water white i.e. clear transparent and consistently so because the polymerisation technology used is such that the reactor vessel does not foul-up for at least 1½ years use.

For footwear, tyres and retread compounding we have often been asked, what is the difference between 96% Cis and the 98% Cis BR’s with respect to wear resistance, skid resistance and rolling resistance or heat build-up properties. In pure 100PHR BR formulations, you may be able to detect slightly better tensile, tear, wear and resilience but not skid resistance for the 98% Cis BR’s, but in practical blend formulations, it is difficult to discern any difference between 96% & 98% Cis BR’s. We have had 10 years experience using BR 9000.

97. Bloom in Chocolates!

Rubber technicians can take solace that bloom problems (See our Short Notes #3) are not confined only to the rubber industry. Chocolates bloom when tiny crystals that can reflect light giving it a glossy appearance melts and on recooling the fat crystallises and the crystal uncontrolled growth reaches a size that can diffuse the reflection of light from the surface and gives it a dull appearance or bloom. Chocolate manufacturers try to prevent this by a tempering process, cooling down from 45^OC to 27^OC and raising the temperature again to 30^OC which ensures that the fat crystallises in a thermodynamically stable crystal form. But then exposing a bar of chocolate in a hot car and then cooling it down again with the air-con one can easily upset fat crystal thermodynamics. Apparently a long lasting chocolate that remains glossy on storage has yet to be discovered.

96. The TPES, TPVS & MPRS Factor

We have touched on the plight of the NR industry and the prolonged depressed prices such that today a kg of NR cannot even buy me a mug of beer at my watering hole. I have hinted that perhaps it is due to an oversupply of NR and we should try to balance the supply and demand situation. However lately, studying the statistics of total elastomers production and consumption for Year 2000, it just struck me how much progress the elastomeric thermoplastic elastomers (TPEs), thermoplastic vulcanisates (TPVs) and melt processable rubbers (MPRs) have made since 1950’s. The International Rubber Study Group IRSG revealed that for Year 2000, total elastomeric market was 17.8m MT with synthetic rubbers accounting for 10.5m MT and NR at 6.3m MT. Simple arithmetics show that for Year 2000, TPEs+TPVs+MPRs must have accounted for 1m MT. Now statistics can be confusing as another report claims that consumption of TPES alone accounted for 1.1m MT in Year 2000. This brings us to statisticians’ understanding and inclusion of what elastomers are elastomers besides the traditional SRs. With the introduction of TPEs , TPVs & MPRs, the old definition for elastomers is now obsolete.

Whatever it is, more than 1m MT a year of TPEs, TPVs & MRPs must have encroached into the NR markets and a new factor has to be considered. Hence R&D is more vital for the NR industry at this point of time.

The launching of Elgem Technology and Kraiburg in Malaysia of a new heat and oil resistant TPE grade called E² based on R&D work on expoxidised NR at MRB – Tun Abdul Razak Research Centre is certainly welcomed news.

95. Malaysia – A net importer of NR!

Lee Iacocca predicted years ago that USA would one day buy more foreign brand cars than American brand cars. It has happened in April 2001 where foreign brand cars outsold American cars 50.6% to 49.4%. However 349,712 American car brands sold a month is no chicken feed.

The recent NR monthly production figures in Malaysia have shown an alarming rate of decline and that day when Malaysia becomes a net importer of NR cannot be too far away – perhaps even in the short term within the next 3 years, if prices remain as they are in the last few years. Producers and consumers of NR must consider the ramifications and strategies. Fortunately for NR consumers there is still no shortage of NR from our neighbours at least in the short term.

94. Badminton Shoes – “D MaQ™” Breathable

I am one of those who grew up with our BATA Badminton Masters in the late 1950’s and still play a bit of Doubles and have gone through pairs of Power, Carlton and Nike badminton shoes. I am aware of the High-Tech shoes worn at Thomas or World Cup series but these are rather expensive and often not even available in this country.

My dear wife Cathryn and I used to regularly visit Hatyai, she for her shopping and Thai tit-bits and I for my indulgences in Thai ancient massages (not at The Pink Lady please). On a trip for her tennis shoes, we were drawn to a shoe in a demo watertank (Fig.1). It was obvious that the tongue and that part between the Vamp Wings are breathable. We appreciate that breathable fabrics are readily available but to make the whole tongue breathable requires special efforts. On closer examination, I found the 6mm sockliner red microcellular material good and the outsoles of MaQ™ Grip antislip compound a bonus and with double flex grooves to give better flexibility.

(Fig 2.)On trying on the shoes I was pleasantly surprised that they now have non-slip laces i.e. you tie the knot and it stays put.

I bought a pair of the D Maq™ Network, not because it is made by Union Footwear, a customer of ours for PBPCs, but because the shoe design is also suitable for tennis, a slower game (at least they allow the ball to drop before you hit it) which I have to switch over soon as my team mates have recently relegated me more to Mixed Doubles.

It is nice to note that an ASEAN country is coming out with high-tech badminton shoes and with their own brand name to boot. For more info – www.d-maq.com

93. Molecular Sieve Dessicant – Zeolite

Writers have a tendency to redefine words to describe things or processes in their own fields, examples of some are given in Item 92. Another example is “pneumatogen” used for CO₂ and N₂ liberated by blowing agents in microcellular rubber manufacture.

My interest in dehumidifying drying of wet rubber granules has led me to discover a “molecular sieve dessicant” in industrial dehumidifying drying units. Zeolite is not precipitated silica like “Zeosil”. There are some 80 zeolites which occur naturally and more than 200 synthetic zeolites are known after 30 years of aluminosilicate material synthesis. As molecular sieve dessicants, zeolite usage is minor. Main usages are as ion exchange materials. One zeolite “Clinoptilolite” used to mop up caesium and strontium in the Chernobyl disaster. Another Zeolite P is used in conjunction with water sensitive percarbonate bleaching agents to remove calcium ions rapidly from hard water.

Yes, besides synthetic ultramarine blue (Item 10) we can learn quite a bit more from Mother Nature old rocks.

92. English As She Is Spoken.

I have touched on the difficulties of Technical English (Item 81). Charles A. Harper’s Glossary of Terms and Definitions¹ for the plastics industry raised this rubber-man’s eyebrows. Some examples are given below and the readers can draw their own conclusions.

1.	Penetration	:	Entering of one part or material into another.
2.	Necking	:	Localized reduction of the cross-sectional area of a tensile specimen that may occur during loading.
3.	Cleavage	:	Imposition of transverse or opening forces at the edge of adhesive bond.
4.	Allowables	:	Statistically derived estimate of a mechanical property based on repeated tests. Value above which at least 99 percent of the population of values is expected to fall with a confidence of 95 percent.
5.	Alcohols	:	Characterised by the fact that they contain the hydroxyl (OH) group, they are valuable starting points for the manufacture of synthetic resins, synthetic rubbers and plasticisers.

Note 1 – Modern Plastics Handbook. Publd. by McGraw Hill 2000.

91. Athletic Footwear Outsole Wear Resistance.

Rubber technicians involved in R&D often wonder which Abrasion test DIN, Taber or Akron gives the best results to predict service performance. We don’t know. SATRA seems to favour DIN¹ and Nike uses their own in-house standard based on Akron Abrasion volume loss (cc) at 3000revs/ 6lbs/ 15^O. Readers may wonder what athletic shoes require the best Akron Abrasion resistance. Readers may also believe that Polyurethanes (PU) should give the best Akron Abrasion results and not often used because of price factor. Readers trying to find such answers in published literature will face difficulties due to limited publications and where published, wear resistance are measured either in DIN, Taber or Akron or their indices making it difficult to draw comparisons.

A publication on Nike beach sandal outsoles R&D² revealed that it is possible to achieve Akron Abrasion loss of 0.08cc with non-PU formulations and opted for one with a good compromise of wear + wet grip properties at 0.20cc loss based on a non-aromatic oil extended High Styrene Resin Rubber + a high styrene SBR. This is already as good as a 80NR + 20BR truck tyre retread formulation³ if we convert mm³/500 rev to Nike standard Akron Abrasion test.

A rare publication on Millable Polyurethanes For Athletic Footwear⁴ revealed that the best Akron Abrasion loss 0.096 – 0.132cc results can be obtained by the use of less light stable polyester PU’s whilst the millable polyether PU surprisingly can only give Akron Abrasion loss of > 0.78cc.

From our knowledge we are aware that the best Akron Abrasion resistant outsoles are used in tennis shoes achievable without PU but with silane coupled silica formulations. Akron Abrasion loss of such outsoles can be < 0.10cc and I can assure you that my wife’s tennis shoe soles outlast the uppers.

Reference

1.	Carter, A.R. & Turner, R.H.	(1999)	Thermoplastic rubber as a shoe soling. Rubber World. Sept.
2.	Winston, J. & Ames, K	(1997)	Development of an outsole compound for outdoor footwear. Rubber World, Dec.
3.	MRPRA	(1984)	The Natural Rubber Formulary and Property Index. Chp. 13.3
4.	Ahnemiller, J & Patterson, D	(1993)	Millable polyurethanes for athletic footwear. Rubber World, April.

90. Biodegradable Plastics From Palm Oil.

The Chapter 12 on “Plastics Recycling and Biodegradable Plastics” by Dr. Susan E. Selke in Modern Plastics Handbook makes very interesting reading with 257 references. I particularly like her pointing out “One way to obtain biological plastics is to use natural polymers, that is those formed by living organisms.” We wished she