August 2005

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Polyurethane Resin

Soy Resin Update

High Temp Resins

for PultrudersPolyurethane Resin

Soy Resin Update

High Temp Resins

for Pultruders

18 | Composites Manufacturing | www.cmmagazine.org | August 2005

Unsaturated polyesters (UPE) and vinyl esters (VE) havebeen the workhorse resins in the pultrusion industry for aquarter century or more. In efforts to expand theirmarkets and differentiate their products, however, pultrud-ers are constantly seeking out new materials and processes

that can mitigate some of the limitations of traditional resins such asbrittleness or slow reactivity.

During the past six years, polyurethane (PU) resins have been developedand successfully commercialized that exhibit superior strength anddamage-tolerance relative to traditional UPE and VE pultrusion resins(Ref. 1-8 at end of article). These outstanding composite properties arecomplimented by the potential for high pultrusion line speeds that can beachieved using polyurethane matrices.

Several resin suppliers and pultrusion manufacturers have reportedtransverse profile strengths twice that of unsaturated isophthalic polyesterresins and excellent damage tolerance (impact, machining and fasteners).In some cases, line speeds in excess of 2-meters/minute (79-inches/minute)have also been reported.

The high transverse strength, interlaminar shear strength, and damageresistance exhibited by polyurethane composites create additional potentialfor simplifying the reinforcement layup, reducing profile thickness andperhaps making unidirectional profiles in place of mat-reinforced parts.

Such advantages do not come without new challenges, however, as PU

resins require their own unique material handling and processing methods.Over the past six years, a substantial body of knowledge has beendeveloped that can mitigate common cost and processing concerns.Huntsman polyurethane pultrusion resins have been commercialized orare under development for use in a wide range of applications includingfenestration (window lineals and architectural moldings), waste watertreatment beams, cooling towers, sheet pile, ladder rails, commercial truckcomponents, and sporting goods.

According to Terry Sutherland, President of CE Composites (Ottawa,Ontario, Canada), “[P]olyurethane resins process easily and robustly andare much tougher compared to the epoxy matrix we formerly used in ourBALLISTIK® hockey sticks.”

As with any other new resin technology, polyurethane chemistry andprocessing must be learned and mastered to optimize profile production.There is a perception in the pultrusion industry that these new require-ments present an insurmountable barrier for practical application ofpolyurethane resins.

Let’s address this perception by providing a practical discussion ofinjection box design, material handling, component meteringequipment, die design, and process conditions used for pultrudingpolyurethane profiles. In addition, neat resin and urethane compositeproperties will be presented and a cost model will be discussed to takeadvantage of these properties through redesign of the profile geometry

Attention PultIs it Time to Explore PolyurethaneResin Chemistry and Processing?By Michael Connolly, John King, Trent Shidaker, and Aaron Duncan

Figure 1. Schematic of a Typical Polyurethane Pultrusion Set-up.

Photo courtesy of Creative Pultrusions

Official Magazine of the American Composites Manufacturers Association | 19

and reinforcement construction. Using the guidelinespresented in this paper as a starting point, manufac-turers can be confident of running a robust pultrusionprocess with continuous line operation. A schematicof a typical polyurethane pultrusion set-up is shownin Figure 1.

Material PropertiesSeveral previous studies (Ref. 3, 6-8 at end of article)have reported on the excellent physical properties thatcan be attained with polyurethane resin-based pultru-sion profiles. Properties of the neat polyurethane resinbased on RIMLINE® SK 97007 polyol blend andSUPRASEC® 9700 isocyanate are shown in Table 1.With a general knowledge of neat resin properties, onewill recognize that the strength, impact resistance, andstrain-at-break are reasonably good compared to otherresins of similar modulus and glass transition temperature, however, notspectacularly so.

The true value of using PU resins is much more apparent after evaluat-ing composite properties. The flexural properties of a profile pultrudedfrom an unsaturated isophthalic polyester and a polyurethane resin arecompared in Figure 2. The reinforcement lay-up is identical for bothresins. The profile is 2.41-mm (0.095-inch) thick and contains two 230-g/m2 (0.75-oz/ft2) continuous strand mats (CSM) and rovings for a totalglass content of 65 wt. percent.

Since the flexural modulus of the composite is dominated by thereinforcement, little difference is observed between the UPE and PU.However, the flexural strength and strain-at-break are 88 percent and 66percent higher parallel to the fibers, respectively, and 120 percent and 100percent higher perpendicular to the fibers, respectively, for the PUcomposite versus the UPE.

The explanation of this significant property improvement is multifac-eted. Polyurethane resins exhibit excellent wetting efficiency and adhesionto the glass reinforcement. Combining these effects with a moderatelytough resin, a nearly optimal synergy of stiffness and toughness betweenthe PU resin and the glass reinforcement is created. Since standard, multi-resin compatible rovings and CSM was used in this study, there is potentialfor even higher performing polyurethane composites with optimized glasssizing technology.

Considering their high strength compared to UPE composites, PU-based pultrusion profiles can be fabricated with all rovings whilemaintaining transverse strength and increasing longitudinal stiffness,greatly simplifying the guiding system. Analogously, PU profiles couldalso be manufactured with thinner walls at constant stiffness compared toUPE based profiles. To further understand the value of the high strengthof PU composites, the corner strength of an L-profile (15.2-cm x 2.54-cm, 6-inch x 1-inch) of varying thickness was evaluated (Figure 3). In thisexperiment, the L-profile was clamped in the tensile testing equipmentand the corner strength (load per unit width) was evaluated for specimensapproximately 25.4-mm (1-inch) wide by constraining the short leg of theprofile under a 6.35-mm (0.25-inch) diameter bar and pulling up on the

long leg of the L-profile.As with the flat sections discussed above, the standard UPE profile at

2.41-mm (0.095-inch) contained two 230-g/m2

(0.75-oz/ft2) continuousstrand mats and rovings for a total glass content of 65 wt percent. Asshown in Figure 3, the load-to-fracture for the all-roving PU profile versusthe CSM reinforced UPE profile increased by 18 percent at 2.41-mmthickness. At 2.03-mm (0.080-inch) thickness, the unidirectional PUprofile exhibits similar corner strength to the standard UPE samples.However, the 1.65-mm (0.065-inch) unidirectional PU sections displayedmuch lower strength than expected.

Based on the trend observed with the 2.41 and 2.03 mm profiles, acorner strength of approximately 4 kg/cm would be expected for the 1.65mm profile. Upon closer examination, it was determined that the devel-opmental 1.65-mm die was improperly engineered. The standard 2.41-

truders Practical Guidelines for Injection

Box Design, Component Metering

Equipment, and Processing

TABLE 1 – Physical Properties of NeatPolyurethane Pultrusion Resin(RIMLINE® SK 97007 Polyol with SUPRASEC® 9700Isocyanate)Property SI Units English Units

Tensile Modulus 2925 MPa 424,100 psi(ASTM D638)

Tensile Strength 71 MPa 10,300 psi(ASTM D638)

Tensile Strain-to-Failure 5.9 %(ASTM D638)

Notch Izod Impact 43.3 J/m 0.81 ft-lb/in(ASTM D256)

Glass Transition 135-140° C 275-284° FTemperature (DMA)

Figure 2. Comparison of Flexural Properties of Unsaturated Polyester andPolyurethane Pultruded Properties.

are commercially available including: metering pumps or cylinders, resintanks, a mixhead and transfer hoses, mixing elements and a solvent flushsystem. Complete metering systems with a broad range of technical sophis-tication can be purchased from several commercial suppliers. It is feasible tooperate such turn-key systems directly from the pultrusion machinecontroller, allowing real-time component metering control and almostcompletely automated resin processing.

Pumps/CylindersComponents may be metered either by air-driven cylinders or by electricallydriven pumps. Single-acting cylinders can be used, but double-actingcylinders are preferred as they provide minimal flow fluctuations when thecylinder reverses direction. Cylinder pumps are rugged, reliable and can beeither fixed or a more versatile variable ratio setup which allows for process-ing with and without fillers. An air pressure regulator must be installed tocontrol the flow rate from the pump.

Electrically-driven gear or progressive-cavity pumps can also be used,providing a smooth continuous resin flow with little pressure fluctuation.Electric motor(s) control either both pumps (fixed ratio) or each componentindividually (variable ratio). Component ratio and flow rate are controlledby the motor speed which is critical to maintaining optimum mixing. Gearpumps are not suitable for use with abrasive fillers (generally in the polyolside). Progressive cavity pumps can be used with fillers but are generallymore expensive than gear pumps. A typical arrangement would use a gearpump for the isocyanate and progressive cavity pump for the polyol.

Pumps must be sized according to the largest product to be run andlinespeed requirements. The volume of resin per length of product times thelinespeed will determine the lowest total resin volume output for which thepumps should be sized. However, very large pumps may be difficult tocontrol for very small resin throughput.

mm and prototype 2.03-mm dies were designed with a smooth3.175-mm (0.125-inch) radius inside corner. However, the 1.65-mm die was merely beveled at a 45 degree angle, creating a localstress concentration and premature failure during testing as mightbe expected in this situation.

Despite this design flaw, the 1.65-mm PU profile with two matsexhibited a 52 percent increase in corner strength compared to thestandard 2.41-mm UPE profile. This experiment reveals a greatpotential for PU resins in production of thinner and potentiallylighter weight, lower cost pultrusion profiles.

Cost AnalysisThe outstanding material performance of polyurethane profilesdescribed above does, however, come at a cost premium relative tocommon isophthalic unsaturated polyester resins when consideringresin cost alone. In the current climate of severe price volatility inresin costs, PU resins are typically 40-60 percent more expensive than UPEresins and are similarly priced to many vinyl esters.

While the cost of PU resin is greater than UPE resin, the toughness,damage tolerance and strength of polyurethane resins bring potential tosimplify and reduce the cost of the reinforcement layup in pultrusionprofiles by replacing mat with rovings. Further, converting mat to rovings inthe design will increase profile stiffness and liberate the potential to reducethe overall composite geometry. These two design elements together canactually offer a cost reduction for PU versus UPE.

Using the physical property assets of PU composites to their fullpotential, a cost analysis (Figure 4) revealed potential for significant cost andweight savings in an I-beam section. Such a beam 3.3-mm (0.130-inch)thick may contain three 300-g/m2 (1-oz/ft2) continuous strand mats (CSM)and have a total glass content of 59 wt. percent. However, under theconstant thickness assumption in this model, it is not possible to attain costequivalence between PU and UPE profiles even when using only two 230-g/m2 (0.75-oz/ft2) mats and filling the remaining profile space with rovings.However, a significant increase in the bending stiffness (+22 percent) of thebeam will be obtained due to the extra rovings.

On the other hand, both weight (-13 percent) and cost savings (-7percent) may be achieved at equivalent beam stiffness by reducing thenumber and weight of mats and the wall thickness (2.76-mm, 0.109-inch). Depending on design intent, structural components may be fabri-cated to take advantage of either the higher stiffness at constant cross-section or lower weight and cost with reduced wall thickness.Experiments are in progress to prove the viability of this model, specifi-cally whether beams pultruded with a polyurethane matrix have sufficienttransverse, bearing and buckling strength at reduced wall thicknesscompared to UPE matrix profiles. The results of these new experimentswill be the subject of a future article.

Metering Equipment Polyurethane resins are two-component systems comprised of a polyoland an isocyanate, typically based on a modified polymeric MDI(diphenylmethane diisocyanate). The polyol is a fully formulated blendof base resin, catalyst, internal mold release (IMR) and other additives.This blend does not usually include filler, colorant or UV stabilizers,for example.

To process this system, a two-component metering unit is requiredfor production runs due to the limited pot-life of the mixed resin (15-22 minutes depending on ambient temperature and mix quality). Themetering unit dispenses mixed resin into a closed injection box orinjection die. However, limited open-bath runs are possible even forrelatively large parts provided the bath volume is kept to a minimumand fresh resin is regularly added.

The required metering unit is comprised of several subsystems which

20 | Composites Manufacturing | www.cmmagazine.org | August 2005

Figure 3. Comparison of Corner Strength of PultrudedUnsaturated Polyester and Polyurethane L-Profiles with Various

Glass Construction.

Figure 4. Comparison of Cost, Weight and Stiffness ofUnsaturated Polyester and Polyurethane I-Beams with Various

Glass Lay-Ups.

Resin TanksOne tank each is required for the isocyanate and polyol to provide resinsupply during pump operation. The tanks are usually installed to providegravity or pressure feed for the pumps and should be sized to minimize theneed for refilling during operation. Both tanks should be sealed to minimizeexposure to humid atmosphere and have a desiccant filter installed toprovide dry makeup air. An agitator is required in the polyol tank to ensurethe IMR and filler, if any, remain homogenized. The hose from theisocyanate tank to the pump should be polyethylene lined for maximum life.An inline strainer on the isocyanate feed is also suggested to prevent debris,if any, from entering the pump. For the highest level of process control,both the polyol and isocyanate tanks may be jacketed to maintain constantcomponent temperature, but this stringent action is not required.

MixheadThe mixhead controls the on-off flow of resin, combining the polyol andisocyanate streams to begin the mixing process. In simplest form, themixhead consists of two ball valves with one handle and a body in which thestreams combine. More sophisticated mixheads can be pneumatically orelectrically operated. Check valves at the entrance to the mixhead valves willprevent backflow into the resin hoses in the case of pressure differentialsbetween the two components. It is also feasible, but somewhat costly, to setup a mixhead with a third stream to add colorant or other liquid additivesdirectly on-line. This approach would prevent contamination of the polyoltank and allow for rapid changeover of profile color. Component mix ratiosmust be adjusted accordingly to compensate for any additive.

Mixing ElementsTypically, static mixtubes are connected to the outlet of the mixhead tothoroughly mix the two components before introduction into the injection

box. The size of the mixtube and number of elements should be sized toprovide good mixing without creating high backpressure. Sizing parame-ters are dependent on flow rate requirements, isocyanate to polyol ratio,component viscosity and component compatibility. Three 0.375-inchO.D. mixtubes attached in series with 24 mix elements in each tube willprovide good mixing for most resin combinations.

Solvent Flush SystemIt is necessary to flush the mixhead, mixtubes and injection box duringshutdown of a pultrusion run to prevent resin from curing in place. Theflush solvent is typically introduced into the mixhead through a three-wayball valve. Resin is initially purged out of the mixhead and mixtubes withair followed by thorough flushing with solvent. Typically a two-gallonpaint pot pressurized with air works well as a solvent container. Thesolvent should have a high flashpoint to minimize the hazard of passing itthrough a hot die. Propylene carbonate is a satisfactory flush solvent toremove uncured polyurethane resin. Pressure regulators should be installedto control air pressure in the solvent pot and for flushing and the mixhead.

Injection Box DesignInjection processing for pultrusion has been practiced in development andproduction for more than a decade. The approach reported by Gauchel &Lehman (ref. 9) using a ‘tear-drop’ injection die is probably the bestknown. Resin injection can be performed internally within the die,typically by modifying it with a weir surrounding the profile, or within aninjection box added on to the die in place of a typical wet-bath. Each hasits advantages.

Development work is best suited for an injection box approach as it canbe fabricated rapidly and inexpensively from high density polyethylene(HDPE). Steel or anodized aluminum will be more robust for the heavy

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use of a production environment. The configu-ration of the wet-out chamber for closedinjection processes is considered to be highlyproprietary to pultruders. However, there areseveral ‘rules-of-thumb’ that are known in thepublic domain.

The most critical design parameter is limiting‘dead spots’ in the injection zone, especially forfast reacting resins such as polyurethanes, wherethe resin can accumulate and possibly cure. Theentire volume of the injection box or die mustbe replenished 3-5 times before the gel time toensure long runs can be made without gelation.Mathematically, this can be expressed as follows:

For example, for a profile with 3.23-cm2 (0.5-in2) cross-section at 50 volume percent (68 wtpercent) glass, a 500-ml injection box will turnover five times in 20-minutes at 0.77-m/min(30.5-in/min). As this line speed is usuallyachieved easily, long production runs should notpresent problems in this case.

Profiles can be fabricated with polyurethaneresin either using rovings alone or a combinationof mat and rovings. Each requires a differentapproach to injection box design, particularly inconstraining the reinforcement into the correctlocation and preventing leakage of resin fromthe injection box.

For unidirectional profiles, especially thosethicker than 2.5-mm (0.098-inch), rovingsshould be fed through the back plate of theinjection box through a series of tapered slotsconforming to the shape of the finished profile.High resin percolation along the length ofrovings presents a challenge in eliminating resinleakage. To seal the back plate, the slots shouldcompress the rovings to 10-15 percent less thantheir thickness in the finished profile. Rovingsshould be guided into the die at an angle to aidresin turn-over in the box and keep the rovingsat the surface of the profile. Entrance angles of3-5 degrees should work satisfactorily.

For mat reinforced profiles, uniform rovingdistribution is the key to producing pultrudedprofiles free of sink marks and scaling. The matand roving should be guided through a slot(again with 10-15 percent compression) in aform as close as possible to the profile shape.Carding systems developed for open-bathprocessing can often be used to guide dryreinforcements into the injection box. Once

rovings enter the box, tension will prevent themfrom redistributing. Upstream carding has asignificant impact on both the distribution andtension on both rovings and mat within theinjection box.

In the case of both unidirectional and matreinforced profiles, optimum wet-out is achievedthrough a combination of pressure andresidence time in the injection box. For a 30.5-cm (12-inch) long box running at 1.8-m/min(72-in/min), the residence time of the reinforce-ment in the box is only 10 seconds. Obviously,substantial pressure is required to wet thereinforcement in such a short time. With a well-sealed box, injection pressures of 7-10 Bar (105-150 psi) are achievable although 3-5 Bar (45-75psi) is more common. The mixed polyurethaneresin typically is injected through two or moreports to smooth out pressure and velocitygradients in the box or weir. The location andnumber of ports has a great impact on wettingefficiency.

Die DesignThere are no special die design requirements forpultruding polyurethane resins compared tostyrene-based resins. A typical die has a 3.2-mm(0.125-inch) inlet radius and has parallel wallsalong the full 0.9-1.0 meter (36-39 inch) length.Dies designed with an inlet taper may be used,but must have cooling on the entire taperedsection to prevent die lock. Certain dies mayhave an exit taper. Such dies can be used as well,but may limit line speed if the gel zone shiftsinto the exit taper region, degrading surfacequality. Polyurethane resins shrink considerablyless than styrene resins, typically 2.0-2.5 percentfor the base resin and approximately 1.0 percentor less for the composite. Although there havebeen limited studies directly comparing layups,pull forces for PU pultrusion have been found tobe similar to UPE and VE despite the lowshrinkage.

Recommended ProcessConditionsThere is an impression within the pultrusionindustry that polyurethane resins are difficult toprocess and are prone to die lock. With a wellformulated PU resin system and appropriateprocess conditions, polyurethanes exhibit quiterobust and reproducible processing. Highquality PU pultrusion profiles have been runcontinuously for over 48 hours at 60inches/minute using a standard resin having a20-minute gel time. This run was not termi-nated due to gelation in the injection box or dielock, but simply because sufficient profile hadbeen produced. Using a well-designed closedinjection box and dosing resin with a meteringpump, runs of indefinite time are feasible. Shortruns of 30-60 minutes are also possible in an

open bath with minimized dead spots and goodresin mixing. In contrast to die lock issues foundin epoxy pultrusion, line purges up to 5-minutesin length have been performed without restartproblems during PU runs when required toaddress saw or reinforcement concerns.

As shown schematically in Figure 1, the dieshould be set up with cooling at the entrance(~10-cm, 4-inches) to prevent heat fromdiffusing into the injection box, causing dielock. Production runs typically use two subse-quent heating zones with Zone 1 at 160-177°C(320-350°F) and Zone 2 at 190-199°C (375-390°F). At steady state conditions, Zone 2 willremain heated by the resin exotherm. Normally,Zone 3 is unheated and allowed to cool byambient conditions or it may be actively cooled.At line speeds over 1.5-m/min (6-ft/min), activecooling of the die may be necessary to keep theprofile exit temperature below 120°C (250°F)and limit possible warpage. Profile cooling withwater after exiting the die is also useful toprevent damage by the pullers.

For profiles thicker than 6.2-mm (0.25-inch)at high line speeds (> 1.5-m/min, 6-ft/min), itmay be necessary to heat Zone 3 and/orlengthen the die to ensure cure in the core of theprofile. In this circumstance, line speed limita-tions result from heat transfer both into and outof the profile, not from resin conversion. Linespeeds up to 1.8-m/min (85-in/min) have beenrun with unidirectional profiles while maintain-ing good surface quality and low pull forces. Itis feasible to run similar line speeds with matreinforced profiles using the appropriateinjection box design and good reinforcementguidance as well as sufficient heater wattage andresin pump capacity.

Material HandlingAs noted earlier, the polyol component shouldbe mixed vigorously before use and continuallyduring use. Care should be taken to limitexposure to air as the polyol is somewhat hygro-scopic. Since CO2 will be generated when MDIreacts with H2O, the absorbed moisture can leadto resin foaming upon mixing with theisocyanate. Similarly, any additive such asCaCO3 filler or colorants should containminimal moisture. However, it is not requiredto dry the additives or reinforcements since alimited amount of moisture can be toleratedwithout degrading processing or profile quality.

The MDI should remain in enclosedcontainers except during transfer operations.With prolonged exposure, MDI will react withH2O in air foaming the PU resin, solidifying ofsome MDI in the tank and perhaps clogging theequipment filters. Reaction with moisture in theair is not an issue for short term exposure (up toseveral hours time) for typical material transferoperations. Small amounts of unused MDI can

22 | Composites Manufacturing | www.cmmagazine.org | August 2005

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be decontaminated with a mixture of water,surfactant and ammonia according to theMSDS. Alternately, the MDI can be reactedwith residual polyol in a well-ventilated area.Care should be taken to limit resin volumes toprevent excessive exotherm generation.

EHS MattersAll resins used in the composite industry presentenvironmental, health and safety (EHS) hazardsof one kind or another. Styrene is currentlyunder study by the US EnvironmentalProtection Agency (EPA) and could be listed asa carcinogen, although that scenario is unlikely.Epoxy curatives, especially aromatic amines,may induce dermal sensitivities over time, someare carcinogenic and many exhibit strong odors.

The two-component polyurethane resinsystems described in this paper are compliantwith the EPA’s Maximum Achievable ControlsTechnology (MACT) rules and do not usestyrene or generate volatile organic compounds(VOC). For polyurethane resins, the polyolcomponent presents relatively few EHS hazardsother than the acidic nature of the IMR which ispremixed into the blend. The fully formulatedpolyol can be easily handled with simplepersonal protective equipment (PPE) such asnitrile or butyl gloves and safety glasses.

The liquid isocyanate component (apolymeric MDI variant) on the other hand canlead potentially to long-term occupationalexposure issues (allergic-type respiratory ordermal sensitivities) if improperly processed,handled and stored. However, the requiredPPE, training for use, handling and storage andmonitoring of worker exposure are all well-known and easy to implement. Compared totoluene diisocyanate (TDI) and aliphaticisocyanates which are volatile and hazardous atambient conditions, MDI has a very low vaporpressure (<0.0006-mm Hg at 25° C) and is alimited respiratory hazard near 25° C unlessformed into an aerosol. Nitrile, butyl orneoprene gloves and safety glasses are therecommended PPE. Latex gloves do notprovide sufficient protection. Ventilation is notnecessary for normal transfer operations ofMDI at ambient conditions.

At the exit of a pultrusion die, Joshi et al.(Ref. 5) observed locally elevated concentra-tions of MDI vapor which increased as afunction of line speed. Very small amounts(PPB levels) of MDI volatilize off the pultrudedprofile due to incomplete conversion. Withminimal ventilation, Joshi et al. (Ref. 5) alsofound exposure of pultrusion line operators waswell below OSHA and ACGIH MDI exposurelimits. Based on this study, ventilation controlssuch as a canopy hood are recommended at thedie exit and over all large volumes of mixedresin and atmospheric (or hygiene) monitoring

should be done to ensure the ventilationcontrols are sufficient to keep local MDIconcentrations below OSHA limits.

Development of pultrusion profiles based onpolyurethane resins has advanced in the past sixyears to full commercialization. PU compositeshave proven to exhibit superior strength andtoughness compared to UPE and VE resins. Totake full advantage of these properties, PU resinsmust be processed using methods that are newor at least not widely known and understood inthe pultrusion industry. Using the guidelines

outlined in this paper, most pultruders shouldbe able to produce moderately complex profileswith polyurethane resins. Processing, guidesystem and injection box design optimization bythe pultruder will lead to full utilization of thepotential of the polyurethane resin.

Product Manager Michael Connolly, Ph.D, SeniorDevelopment Engineer John King, DevelopmentManager Trent Shidaker, and DevelopmentEngineer Aaron Duncan work for Huntsman

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(“Pultruders...” continues on p. 60)

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Corporation in Auburn Hills, Mich. Connolly has been employed inpolyurethane product development for 9 years at Huntsman and has 16 yearsexperience in a range of polymer materials development roles: 248.322.7416;Michael_Connolly@ huntsman.com. King served as a mechanical engineer inpolyurethane composites for 4 years and for 25 years in numerous otherengineering design and development roles: 248.322.7414;John_King@huntsman.com. Shidaker has been employed as manager orproject leader in polyurethane foam and composite development at Huntsmanfor 10 years 248.322.7409; Trent_A_Shidaker@huntsman.com. AndDuncan has worked in adhesive, coatings, elastomer, and composite develop-ment for 3 years: Aaron_Duncan@huntsman.com.

References• Joshi, R.R., Varas, L.L., Padsalgikar, A.D., “Polyurethanes in Pultrusion: Styrene Free

Alternative Systems”, International Composites Expo 1999-SPI, (Society for the PlasticsIndustry), April 1999.

• Joshi, R.R., Cheloas, E.H., Varas, L.L. “Pultruding with Polyurethane Composites,”Proceedings of Composites 1999-CFA, (Composites Fabricators Association), October 1999.

• Joshi, R.R., Cheloas, E.H., Stapleton, R., DeLima, A., “Polyurethanes in Pultrusion II:Comparative Study with Conventional Resin Systems Used in the Industry,” Proceedings ofComposites 2000-CFA, (Composites Fabricators Association), September 2000.

• Hartman, P., Cheolas, E.H., “Thermoset Polyurethane Pultrusions to Provide DamageTolerant Composite Options,” Proceedings of SAMPE 2000, (Society for the Advancement ofMaterials and Process Engineering), September 2000.

• Joshi, R.R., Cheolas, E.H., Cassidy, E.F., Karoly, W.J., Coffee, H.D., “Polyurethane BasedPultruded Resins Improve the Environmental Image of Composite Materials,” Proceedings ofComposites 2001-CFA, (Composites Fabricators Association), October 2001.

• Coffee, H.D., Perry, M.J., “Processing Techniques for Reinforced Thermosetting UrethaneComposites,” Proceedings of Composites 2001-CFA, (Composites Fabricators Association),October 2001.

• Vaughn, J.G., Lackey, E., Coffee, H.D., Barksby, N., Lambach, J.L., “Pultrusion of Fast-GelThermoset Polyurethanes: Processing Considerations and Mechanical Properties,” Proceedingsof Composites 2003-CFA, (Composites Fabricators Association), October 2003.

• Sumerak, J.E., “Pultrusion Gets Tough: Polyurethane Resin Offers New Growth,” CompositesFabrication, (American Composites Manufactures Association), February 2004.

• US Patent 5,747,675 “Apparatus for Resin Impregnated Pultrusion,” Gauchel, J.M. &Lehman, R.N., Owens Corning Fiberglass Technology, Inc., 1995.

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(“Pultruders...” from p. 23)