The technical service magazine for the rubber industry Volume 256, No. 5

AUGUST 2017

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@rubberworld

Quality rubber accelerators

Cure systems in natural rubber:Comparison of sulfur, selenium and tellurium

Scorch protected peroxidefor processing chlorinated polyethylene

Impact of carbon blackon durability of vulcanized rubbers

Unique composite powderis transforming rubber compounding formulas

2017Chemicals & Materials

ACS Events, page 67

shows the naturally ‘tacky’ nature of the powder, with smaller particles clinging to each other; yet it is still free-flowing, and readily disperses when introduced into formulas containing

Elastomer compoundingRSS undertook independent third party research to determine

-monite powders, and the properties of the modified formulas

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las each were prepared and tested for the three elastomeric -

-cantly shorter mixing cycles and lower integrated power con-

rheometer test data, Mooney scorch times and physical proper-

were completed and shown to be comparable to slightly lower

hardness, tensile, elongation, modulus, tear resistance, specific -

various aging studies, including heat aging, immersion tests in

Unique composite powder is transformingrubber compounding formulasby Pearce Daley, RSS, LLC

has begun to help rubber products manufacturers refine select compounding formulations by improving product perfor-mance, simplifying manufacturing processes and lowering

-fits for rubber compounders with better abrasion resistance, equal or better hardness, tensile, elongation and volume proper-ties, as well as lower mixing times and reduced power con-

Recently completed independent laboratory studies have

three high-volume industrial rubber compounding applications,

Harmonite’s physical properties

composite powder manufactured in a patented, high-tempera-

-pending on product, is a high softening point composition

weight, complex mixtures of polyaromatic carbon ring units -

ing highly polar structure of asphaltenes and resins has been found to exhibit polymeric behavior, physical crosslinking and addition-type chemical reactions (hydrogen bonding, van der

The inorganic phase consists primarily of calcium carbon-ate, aluminum oxide, titanium dioxide, kaolin clay, glass fiber

bagged to a -40 or -70 mesh during the final stage of manufac-

FOLLOW US ON TWITTER @rubberworld 37

Table 1 - SARA analysis

SaturatesAromaticsResinsAsphaltenes

* Typical averaged values of various grades of Middle East and Venezuela bitumen compiled from multiple sources

Typical averagevalues asphalts*

10.4%63%18%8.2%

Typical valuesof Harmonite

15%22%22%42%

Figure 1 - SEM of Harmonite 70

100 m

ConclusionsWhile every application is different and every formula is unique, the preceding experimental results combined with feedback from

function ingredient that can improve formula performance, lower -

process aid, a plasticizer, rheology modifier, thickener, homoge-

oil, ethylene glycol/water and water, as well as abrasion testing -

rable or superior performance in a number of tests; but in other

believed that any differences in physical properties could be readily addressed via minor modification of the experimental formulas, depending on the properties most desired by the end

-hibited by the experimental formulas would be suitable for

38 RUBBERWORLD.COM AUGUST 2017

Table 2 - phase one mixing and power consumption

Rubbercompound

EPDMNitrileSBR/BR blend

Harmonitemixing time

(minutes)23-50% shorter21-28% shorter10-17% shorter

Reduced mixing time impact* (additional operating capacity)

460-1,000 hours/year420-560 hours/year200-340 hours/year

Harmonite formulasintegrated power

consumption20-36% lower25-30% lower10-25% lower

Reduced power consumption impact

$15,000 - $27,000/year savings$16,000 - $19,000/year savings$6,000 - $16,000/year savings

*Basis: 2,000 hours/year operation. Increased capacity based on batch mixing time only. Energy savings based on $.05/kWh. Tests were completed on a 1.6 L tangential rotor mixer, and actual plant results are likely to be different based on specific mixer configu-ration plant set-up and operation.

Table 3 - phase one summary comparison - Harmonite formulas vs. control formulas

Relative % change in physical properties after being subjected to common accelerated aging tests

Heat aged propertiesDurometer ATensile strengthElongation

Fluid immersion

Durometer ATensileElongationVolume

Fluid immersion

Durometer ATensileElongationVolume

Staining

Abrasion resistance

EPDMHose covers/gaskets70 hours at 150°CComparableHarmoniteComparable

Ethlyene glycol/water168 hours at 125°CHarmoniteHarmoniteHarmoniteHarmonite

#1 oil168 hours at 150°CControlControlControlControl

ASTM D925-06e2 AComparable very slight staining.Control slightly better.

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Nitrile RubberFloor mats70 hours at 125°CComparableHarmoniteHarmonite

Water168 hours at 100°CControlControlControlControl

#1 oil168 hours at 125°CHarmoniteHarmoniteHarmoniteComparable

ASTM D925-06e2 AEquivalent – no staining eithercompound

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The better performing compound is listed in the table.

SBR/BR blendConveyor covers70 hours at 100°CHarmoniteControlControl

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ASTM D5963-04 AHarmonite significantly better