Rubber & Plastics News ● August 20, 2012 15www.rubbernews.com

Technical

SBR latex polymers with improved auto-adhesionExecutive summary

Continuously decreasing availability and increasing costs create incentivesto identify suitable alternatives to natural rubber.

Adhesive formulators have blended natural rubber latex with small amountsof styrene-butadiene latex, albeit with a negative impact on adhesive perform-ance.

For some pressure sensitive adhesive applications natural rubber has beenhard to replace because of its superior auto-adhesion characteristics, low tackand good compatibility with tackifiers. Newly engineered SBR latexes mightenable adhesive formulators to substantially substitute SBR for NR.

Such latexes offer improved auto-adhesion through molecular architectureand polymer characteristics.

These new SBRs are fully miscible up to 20 percent with NR, and the homo-geneous blends show the same or better autohesion properties as natural rub-ber in a certain ratio.

The autohesion characteristics are gradually changing with increasing SBRconcentration higher than 20 percent.

This paper discusses the design of new synthetic SBR which can be blendedin with NR at high concentrations without sacrificing adhesive performance forcold seal, tamper evidence and similar applications.

The SBR latexes are fully miscible up to 20 percent with NR and the homoge-neous blends showing the same or better (90/10 NR/SBR) autohesion propertiesas natural rubber.

Autohesion gradually deteriorates with an increasing SBR concentrationover 20 percent. However, natural rubber’s low tack is preserved over a widerange of SBR.

By K. Don Kim, Tibor Pernecker andTim Saddow

Omnova Solutions Inc.

Natural rubber was the earliest poly-mer used in manufacturing pressuresensitive adhesives. Its low Tg, excellentability to bond under light pressure andease of processing made it ideal for PSAapplications.

In today’s applications, it is typicallyused as a raw material to formulate ad-hesive products.

Relative to other polymers, naturalrubber is limited by its high molecularweight, low miscibility with low molecu-lar weight resins, low polarity and lowUV and thermo-oxidative stability re-sulting in discoloration during the life-

time of a PSA product.1, 2

Over several decades, NR graduallyhas been replaced by versatile pureacrylics in formulating PSA, but in someapplications it appears to be difficult toreplace it because of its unique charac-teristics.

One such feature is its autohesion,also known as auto-adhesion or self ad-hesion.

In cold seal or tamper evident enve-lope adhesives the choice of the adhesiveis based on natural rubber’s ability toquickly form a strong autohesion con-tact.

In these applications, after the forma-tion of adhesion contact by two NR lay-

ers, fast polymer diffusion commences,the interface between layers begins todisappear over time and a strong cohe-sive bond forms between the two sides.

The NR-NR interface becomes an or-ganic part of an NR film.

Upon initiating the separation of theinterface, i.e., opening a mailing enve-lope, an NR adhesive typically delami-nates from the carrier paper or film and

provides tamper evidence. Diffusive bonding provides the strong

interaction at the interface. Diffusion theory of polymers describes

such a phenomenon with clarity 3. For diffusion bonding to take full ef-

fect, high molecular mobility at the in-terface, good compatibility and suffi-ciently high molecular weight must bemet, so that fast autohesion can occur 4.

According to the theory of polymer in-terfaces, a full cohesive strength isreached when the polymer molecules atan interface diffuse a distance compara-ble to their radius of gyration and formlarge number of molecular entangle-ments5, 6.

For high molecular weight polymerslike polybutadiene and polyisoprene, theinterdiffusion process is completed with-in three seconds at room temperature7.

This implies that autohesion of NR ispractically instantaneous, making it ide-al for selected adhesive applications.

The excellent autohesion feature ofNR represents a key experimental ob-stacle, however, for studying its autohe-sion by traditional “T-peel” or any othermechanical test method.

For selected applications such as deepfreezer and low temperature adhesive,high performance and packaging tape,NR is not being used exclusively but, in-stead, it is blended with low molecularweight acrylics and styrene butadieneresin latexes for enhanced performanceand cost effectiveness.

Optimization of blended compositionshowever is cumbersome using mechani-cal testing and other methods, like smallangle neutron scattering, and thesemethods are not readily available to for-mulators.

Probe tack experiments are well docu-mented in the PSA industry. Creton andcoworkers8 conducted extensive and de-tailed investigations of model adhesivesusing a customized probe tack analyzercombined with in situ optical observa-tion.

Their experiments focused on adhe-sion between a flat steel probe and anadhesive layer.

Unfortunately, this method cannot bedirectly applied for studying autohesionof NR/SBR blends because the cohesivestrength of the adhesive sample is oftengreater than the adhesion between asteel probe and the adhesive, resultingin complete delamination of the adhe-sive from the steel probe.

The authors resolved this problem byusing paper saturated with NR and

Fig. 2. RM Price Change January 2005-December 2010, NR latex, SBR and blendedoptions. Source: CMAI 2011 Data & Firestone Natural Rubber Weekly NL Price,does not include production, processing or freight costs.

Fig. 1. NR TSR 20 and NR latex versus crude oil pricing.

Table I. Physical properties of natural rubber and SBR.

Fig. 3. Texture analyzer (Texture Technologies, Model TA.XT).

TECHNICAL NOTEBOOKEdited by Harold Herzlichh

See SBR, page 16

RPN20120820P015.qxp 8/15/2012 4:22 PM Page 1

16 Rubber & Plastics News ● August 20, 2012 www.rubbernews.com

Technical

NR/SBR as a test specimen in probe testexperiments and, after determining ap-propriate test conditions, successfullyused the probe tack test method for opti-mization of the composition of NR/SBRblends.

This paper discusses the value propo-sition behind NR replacement with anewly developed synthetic SBR, the per-formance of progressively increasingSBR content blends, as well as the lim-its of replacement based on the compati-bility of the two elastomers.

In the process, we describe a uniquetechnique to measure autohesion of NR.

Economic retrospective Natural rubber is an elastic hydrocar-

bon polymer derived from the sap ofplants such as the Para rubber tree, He-vea Brasiliensis.

According to the International RubberStudy Group 11, total NR and syntheticrubber production reached 24.4 milliontons in 2010, 14.8 percent higher than in2009, reflecting a strong recovery on thedemand for vehicles and tires.

SR accounted for 14.1 million tons (58percent), and NR accounted for 10.3 mil-lion tons (42 percent).13

Although the bulk of rubber producedis synthetic, derived from petroleum,NR pricing historically has tracked pre-vailing global price of West Texas Inter-mediate crude oil, as shown in Fig. 1.

Until the early 2000s, natural rubberand NR latex have experienced slow de-mand growth and declining real dollarprices.

However, since then, rapid industrialgrowth in China, India, Eastern Europeand Southeast Asia has translated intoa greater consumption of NR.

Greater demand, along with limitedreinvestment in plantations, has result-ed in dramatic fluctuations in NR and

latex pricing, leading up to September2008, and followed by a drop in demandand price during the worldwide econom-ic recession of 2009.

Today, a global natural rubber short-age exists and prices have again reachednew highs earlier this year, approaching$3/dry lab in May 2011 for natural rub-ber latex.

What can an adhesive formulatordo?

Adhesive formulators using NR latexhave seen significant price fluctuationsin their raw materials in the last fewyears for the reasons just described.

Continued price volatility and uncer-tainty should be considered when for-mulating decisions are made.

Engineered synthetic SBR latexes en-able the water based adhesive formula-tor to potentially replace a portion of theNR latex with a synthetic product with-out sacrificing product performance.

In addition to the performance evalu-ation of a blended formula, the econom-ics must be evaluated.

Fig. 2 shows the change in raw mate-rial costs of NR latex and SBR using 40percent styrene and 60 percent butadi-ene monomer ratio for a representativeSBR in PSA, as well as two differentblends of NR latex and SBR12, 14.

The following conclusions can be de-rived from Fig. 2.

Blended SBR latex with NR latex low-ers formulated raw material costs.

Over the six-year period shown, NRlatex increased 180 percent, while theblended latex increased 149-167 per-cent, lowering the overall raw materialcosts to the adhesive formulator.

Doing the research on how to formu-late with SBR latex will give the adhe-sive formulator the ability to switchbased on economics.

Evaluating the price/performance re-lationship of a blended formulation al-lows for reacting quickly to future mar-ket changes.

Experimental SBR latex synthesisSBR latex was synthesized with a typ-

ical emulsion polymerization method ina pressurized reactor.

Styrene, butadiene and carboxylicacid are the primary monomers, andsurfactant and other additives includingan initiator are charged to create the de-sirable molecular weight, particle sizeand gel content.

Both chemistry and process tools wereutilized to precisely control the synthet-ic polymer’s molecular weight, its distri-bution and polymeric chains architec-ture.

Using experimental designs, we deter-mined the optimum synthetic polymercomposition and latex physical proper-ties to emulate NR.

Physical properties of the syntheticSBR and NR latexes are shown in TableI. The methodologies used to measureand determine the physical parametersare described below.

The NR latex for our study was LA-XTnatural rubber from Dynatex and wasused without modifications.

The face stock was prepared by satu-ration of the 42 gsm (28 lbs) crepe paperwith natural rubber latex using a labo-ratory roll padder.

The saturated sheets were air dried

for two hours, then placed in an oven at93°C for five minutes. The saturated pa-per created an anchorage with the latexfilm in it.

The NR latex was mixed with SBR la-tex providing six samples with NR/SBRratios of 100/0, 90/10, 80/20, 70/30, 60/40and 0/100.

Free films of each sample were madeusing Meyer rod on silicone release lin-er. These films were dried under roomtemperature for 15 minutes and subse-quently in a 93°C oven. The thicknessesof the dried films were between 25 and35 �m.

Three layers of each film were lami-nated resulting in 75 to 105 �m thickfilm of each.

The sheets were placed in the ovenunder weight at 50°C overnight to pro-vide the enough annealing time betweenfilm and saturated paper.

Autohesion testing The instrument used for the measure-

ment of autohesion is TA.XT plus Tex-ture Analyzer manufacture by TextureTechnologies shown in Fig 3.

It has a stainless steel cone type probeconnected to the probe carrier, which ismoved vertically.

During the sample testing, the forcevs. distance between the probe tip and

SBRContinued from page 15

Fig. 4. Typical graph of force versus debonding distance during separationprocess.

Equation 1. Me.Equation 2. Mc.

Fig. 5a. DMA curves of NR used for calculation of Me.

Fig. 5b. DMA curves of SBR used for calculation of Me.

Fig. 6. Free films of natural rubber/SB blends and their corresponding probe tackcurves: A – 100% natural rubber (NR), B – 100% SB, C – 90/10 NR/SB, D – 80/20NR/SB, E – 70/30 NR/SB, F – 60/40 NR/SB, (The line in insert C marks the integra-tion limit for area calculation).

RPN20120820P016.qxp 8/15/2012 4:23 PM Page 1

Rubber & Plastics News ● August 20, 2012 17www.rubbernews.com

Technicalthe bottom adhesive film were recordedby a computer.

The saturated paper laminated withlatex film was placed in a housing unitunder probe as a stationary adhesivelayer.

For the top layer, the probe tip waswrinkle free wrapped with the piece ofsame laminated paper.

A Peltier plate which was located un-der the specimen docking area main-tained a temperature of 23°C.

This set-up allowed an adhesive filmto come in contact with the film, and theforce could be recorded during upwardmovement of probe.

The autohesion test can be dividedinto two distinctively sequential steps.

First is the bonding or compressionstep, where the probe, covered with sat-urated paper, comes in to contact withthe stationary specimen and keeps itunder compression for a predeterminedperiod of time.

Debonding follows this step duringwhich, at constant velocity, the probeseparates from the stationary saturatedpaper at a constant velocity.

Test conditions were identified byfinding the minimum required compres-sion force, contact time and probe speedfor appearance of fibrillation, fibril for-mation at separation of NR-NR speci-mens.

An example of the force vs. distance isshown in Fig. 4.

Four different stages can be distin-guished during the debonding process:(a) linear, elastic deformation obeyingHook’s law, (b) stress relief by cavitygermination, (c) evolution of fibril struc-ture and (d) fibril failure.

The optimum testing conditions were10 second contact time, 10 lbf compres-sion force, and 0.05 mm/sec probe speed.

Probe tack force The tack force was measured using a

stainless steel probe and it was de-fined as the value of peak force record-ed between the stainless steel probesurface and the stationary latex filmsamples during vertical motion of theprobe.

Glass transition temperatureA Differential Scanning Calorimeter

(DSC Q100 from TA Instrument) wasused to measure glass transition tem-perature, Tg, to detect the compatibilitybetween NR and SBR.

Samples of latex films were scannedfrom as temperature changed from -90°Cto 125°C at a rate of 15°C/min in a nitro-gen atmosphere.

Critical Entanglement molecularweight

The AR-2000 advanced rheometerfrom TA Instrument was used to meas-ure viscoelastic properties of NR andSBR films.

Films were prepared by drying atroom temperature for 48 hours.

Dynamic mechanical analysis meas-urements were conducted by heatingthe samples at 3°C/min, and 10 rad/secfrequency 8 mm diameter parallel platewas used with 2.5 mm sample thicknessin the range of temperature from -80° to250°C.

Equation 1 was used to calculate theMe9.

Where �p is the density of polymer, Ris the gas constant (8.31 x 107 dynecm/mol K), and T is the absolute temper-ature for the onset of the rubberyplateau. Gn is determined from thepoint where tan � shows the minimumvalue in Fig. 5.

Average molecular weight between crosslink points (Mc)

Mc was determined with the insolublematerial swollen in a solvent.

The dried polymer was encapsulatedin a sealed PTFE membrane filter andtumbled in a sealed vial of toluene for 24hours.

After 24 hours, the vial was removed

from the rotator, the sample rinsed withclean toluene, and any surface solventwas quickly blotted with absorbent lint-less towel.

After weighing the swollen gel, a sam-ple was placed on an absorbent towel inthe hood for 30 minutes and then driedin the oven at 100°C for an hour. Thedry gel was weighed.

The Flory-Rhener equation (Equa-tion 2) describes the equilibriumswelling theory well and useful for cal-culation of Mc to evaluate the degree ofcrosslinking related to Me9.

Where � is the volume fraction ofpolymer in the solvent, V1 is molar vol-ume of solvent, �p is the density of thedry polymer, and � is the Flory-Hug-gins polymer-solvent interaction pa-rameter.

Results and discussion Autohesion of natural rubber and SBR During the debonding stage of autohe-

sion experiments (Fig. 6-B), sample fail-ure occurred at the SBR-SBR interfacewithout fibril formation along the sepa-ration surface, while extensive fibrilla-tion was observed with NR-NR samples(Fig. 6-A).

After reaching the peak force value,widespread cavity germination tookplace with NR samples.

The cavity walls oriented in the direc-tion of the applied stress end formedelongated fibril structures.

Upon further deformation, additionalcavities formed within the fibrils, andsome of the primary fibrils split into fin-er ones.

This break up process continued,along with thinning of the primary fib-rils, until the applied stress overcamethe cohesive force of the individual fib-rils, resulting in cohesive failure with-out any sign of the original NR-NR in-terface.

In addition to elastic deformation ofthe primary fibrils, the stress energywas also relieved by continuous cavita-tions inside the elongated fibrils andtheir break up.

On the molecular level, during thedebonding process of two polymer inter-faces, the stress energy can be dissipat-ed by the work against secondary forcesand by a chain pullout mechanism, i.e.,by disentanglement of diffused polymerchains at the interfacial layer.

The cohesive strength of an interfaciallayer depends on entanglement density(De).

When the De value is high, the strongsecondary electrostatic forces delay indi-vidual chain disentanglements, and theinterface appears stronger.

After stress energy reaches a criticalvalue, the entangled chains start to ori-ent and stretch into the direction of theapplied stress.

Further deformation leads to disen-tanglement of the individual chains andstructural failure.

Using the entanglement density of theindividual polymers, we can estimatefailure mechanism of SBR-SBR or NR-NR interfaces.

The entanglement density is the ratioof the weight average molecular weightof the soluble fraction (Mw) and the en-tanglement molecular weight (Me) i.e.,De = Mw/Me.

Literature suggests that only poly-mers which have Me > 10,000 g/mole areable to show fibrillation during thedebonding process10.

While this is valid for the debondingof SBR-SBR interface during the auto-hesion experiments, it is not valid forthe NR-NR interface.

The Me and the calculated De valuesfor NR and SBR from equation (1) are4,100 and 3,500 g/mole and 2,656 and20, respectively. (Table I)

The low peak force and the clean fail-ure at the SBR-SBR interface suggestthat the failure occurred by a simplechain pull out mechanism because oflack of sufficient interaction betweenthe polymer chains and low De value of

Fig. 7a. Effect of NR/SBR blend compo-sition on initial slope, work of adhe-sion, peak force and probe tack force.

Fig. 7b. Total area vs. blend ratio.

Fig. 7c. Peak force vs. blend ratio.

Fig. 7d. Probe tack force vs. blend ra-tio.

See SBR, page 18

Fig. 8. DSC curves of blended latex samples.

RPN20120820P017.qxp 8/16/2012 3:25 PM Page 1

18 Rubber & Plastics News ● August 20, 2012 www.rubbernews.com

Technical

SBR compared to NR. The Me value of natural rubber is sim-

ilar to that of SBR, but its high solublefraction (50 percent compared to 32 per-cent for SBR (Table I) and large De i.e.,average number of entanglements perchain, provide sufficient cohesive energyfor fibril formation during the debond-ing stage.

Both elastomers contain a substantialamount of gel (Table I).

The molecular weight between thecrosslink points (Mc) was calculatedfrom Equation 2 and is not highenough (<1000, see Table I) to form en-tanglements with the linear polymerchains in the case of SBR.

On the other hand, in NR the Mc isslightly higher than Me giving an op-portunity for entanglement formationbetween longer network chains andlinear NR chains, therefore contribut-ing to fibril formation during deforma-tion.

Autohesion of NR/SBR blends The deformation characteristics for

NR-SBR blends are similar to those ofNR.

A 10 percent addition of SBR to NR in-creased the initial peak force (Fig. 7) andhad a fibril “reinforcement” effect during

the debonding process in NR/SBR auto-hesion experiments (Fig. 6c).

In these experiments the sample fail-ure was not cohesive i.e., fibril break,but delamination from either the up-ward moving probe’s surface covered bypaper saturated with the NR/SBR(90/10) blend or from the stationary sat-urated paper.

The fibrils appeared to be too strongto break.

An increase of SBR to NR ratio led tolower peak force, work of adhesion (areaunder the curve), initial slope during thedebonding process (Fig. 7a), and fibrilfailure without delamination from ei-ther saturated paper surfaces (Fig. 6d,e, f).

One possible explanation for the fibril“reinforcement” is the potential plasti-cization of the polyisoprene molecules bythe low molecular weight poly (styrene-butadiene) molecules.

The presences of low molecular weightpoly (styrene butadiene) chains promotealignment of the stereo-regular polyiso-prene, similarly to the well known stressinduced crystallization with cis-polyiso-prene.

In NR/SBR blends with 20 percent orhigher SBR concentration phase separa-tion was observed (see picture in Fig. 6).

The NR/SBR blend free films becameopaque with increasing SBR concentra-tion.

The change in visual appearance wassubstantiated by DSC.

As it is shown in Fig. 8, the 90/10NR/SBR blend has only one Tg which isclose to that of NR.

At higher than 20 percent SBR con-centration, a second small transitionappears and becomes pronounced withincreasing SBR concentration (themedium sized endotherm, just after theglass transition temperature of NR, iscommonly referred to as enthalpic re-covery).

The DSC data show that the SBR isfully miscible to NR, up to 20 percent.Above 20 percent, the SBR/NR interfaceinfluences fibril deformation duringdebonding (Fig. 7).

The De value of SBR dominates overthat of NR (20 compared to ~2,000),gradually deteriorating the autohesionproperties of natural rubber (Fig. 6d, e,f) and its ability to dissipate energy dur-ing the debonding process.

At high levels of SBR, the presence ofgel, which is incapable of forming chainentanglements neither with SBR norwith NR chains, gradually limits ablend’s ability to form fibrils during thedebonding process, and subsequentlydissipate stress by viscoelastic deforma-tion.

Probe tack In probe tack experiments (Fig. 7d)

the low tack of NR was preserved over awide range of blended compositions be-cause of the low adhesion of NR/SBRblends to the stainless steel probe.

In these experiments the cohesivestrength of NR and NR/SBR blends,which was mainly provided by NR, washigher than the blends’ adhesion tostainless steel.

Conclusions We have shown that engineered syn-

thetic SBR latexes can be blended withNR for adhesives in cold seal, tamperevident and similar applications.

These SBR latexes are fully miscibleup to 20 percent with NR, and the homo-geneous blends show the same or better(90/10 NR/SBR) autohesion propertiesas natural rubber.

Autohesion gradually deteriorateswith an increasing SBR concentrationover 20 percent by weight.

However, natural rubber’s low tack ispreserved over a wide range of SBR con-centrations in NR/SBR blends.

AcknowledgementsThe authors thank Ian Everhard for

conducting the autohesion tests, and theAnalytical Solutions Group at the AkronTechnology Center for DSC andRheometer testing of the samples.

References1. Istvan. Benedek, Pressure Sensitive Design andFormulation, Application, vol. II, Martinus NijhoffPublisher and VSP, 2006 2. Alphonsus V. Pocius, Adhesion and AdhesivesTechnology, Hanser, 2002 3. S.S. Voyutskii, Autohesion and Adhesion of Poly-mers, Interscience, New York, 1963 4. U. Giese, R.H. Schuster, KGK Kautchuk GummiKunstoffe, 54. Jahrgang, 12, 600 (2001) 5. Y. Liu, J.C. Haley, K. Deng, W. Lau, M. A. Win-nik, Macromolecules, 40, 6422 (2007) 6. J.C. Haley, Y. Liu, M.A. Winnik, W. Lau, J. Coat.Tecnol. Res., 5 (2), 157 (2008) 7. C.M. Roland, G.G. Bohm, Macromolecules, 18,1310 (1985) 8. R. Schach, Y. Tran, A. Menelle, C. Creton, Inter-diffusion and Tack at Interfaces Between Immisci-ble Polymer Melts, Proceedings of the 29th AnnualMeeting of The Adhesion Society, Jacksonville,USA, 2006 9. L.H. Sperling, Introduction to Physical PolymerScience, J. Wiley & Sons (1992) 10. A. Zosel, Int. J. Adhesion and Adhesives, 18, 265(1998) 11. Rubber Industry Report, International RubberStudy Group, Vol. 10, No 4-6, October-December2010 12. CMAI Price Database, 2011 13. International Rubber Study Group, Latest Rub-ber Statistical Bulletin and Rubber Industry Re-port, March 11, 2011 14. Firestone Natural Rubber, Weekly NR Price

Products

Qualitest introduces2000kN testing machine

Qualitest International Inc. is offeringthe 2000kN Universal Testing Machine,Q2000, which it said is designed forquick and reliable tensile, compression,flexural (bending), shear, peel, fatiguecycling and constant load tests on met-als, composites, alloys, rigid plastics andfilms, elastomers, textiles, paper, board

and finished products.The instrument is suitable to be used

in both production lines, where the op-erator has to be fast and efficient, andaccurately control the test, Qualitestsaid.

It also said it is good for testing labenvironments, where using the ad-vanced software, the users can analyzethe test data, and have full control onprocessing, filing, management andtransmitting the test data to the compa-ny network and database, plus usingmany more functions, Qualitest said.

For detailed specifications and moreinformation, visit www.worldoftest-.com/utm.htm or call 877-884-8378.

Kraiburg releases new TPEbrands for consumer use

Kraiburg is marketing two new ther-moplastic elastomer brands that it saiddemonstrate superior haptics, adhesionproperties and media/weather resist-ance.

COPEC and For-Tec E are designedfor consumer use and are resistant to allinfluences of daily use, such as hand

sweat, alcohol or weather.The COPEC line has a velvety feel, ac-

cording to Kraiburg, and is ideal forcomputer mice, games consoles or earplugs.

The For-Tec E series of compoundswas developed for reliable adhesion tosemi-aromatic polyamides and PA 6.6,the company said.

These adhesion properties in the 2Kinjection molding process permit the useof TPE, for example in the form of sealsor plug-in connections for mobile phonesand MP3 players.

Similar to COPEC, For-Tec E was de-veloped for applications in consumerelectronics and is additionally used inthe power tools sector.

Visit www.kraiburg-tpe.com for moreinformation.

Mitchell says new designsimprove rubber cutting

Mitchell Inc. has launched severalmachine designs and an updated web-site for improved efficiency.

Model 24 is an economical lathe cutterdesigned to cut molded, small ID, short

length tubes, according to the company.This precision machine is designed towork on smaller parts with precise toler-ances, it said.

Mitchell claims its Model 618 preci-sion lathe cutting machine can improvethe bottom line when cutting round orcylindrical parts from rubber, someplastics and composites.

This economical cutter is designedto accommodate a majority of multi-purpose tube cutting applications forseals, rings and gaskets, the companysaid.

The 534 Mandrel Loader is an add-onto Model 618 or Model 111, and can in-crease productivity by reducing downtime associated with loading and un-loading a single mandrel, Mitchell said.It has 10 positions, and can hold up to 8mandrels at one time.

Model 242 is available now with one,two or three heads, and is a fast, efficientangle trimmer, designed to trim or de-flash rubber or plastic parts that requirea precision edge, the company said.

For more information, visit Mitchell’sredesigned website at www.mitchell-inc.com.

SBRContinued from page 17

Qualitest International’s 2000kN Uni-versal Testing Machine.

RPN20120820P018.qxp 8/16/2012 3:24 PM Page 1