THE TA HOTLINE

1 9 9 7 V O L U M E 2

• NATAS review 1• Rheology Navigator Software 1• Edith Turi Honored at PittCon 2• Melting phenomena by MDSC 2• Applications CD released 3• MDSC seminar 3• Organizational events 4• Year 2000 compliance 4• Rheology and Skin Feel 5• An MDSC study of Heat-Set

and Annealing Temperatures 6-7• Thermal Hazards 8

In this issue: Page

T A Instruments proudlyintroduced a newtechnique,

Modulated TGA™

(MTGA™) at thisyear’s NATAS(North AmericanThermal AnalysisSociety) conferencein September.

This patent pendingtechnique is the resultof TA Instruments’continuing research anddevelopment in the area ofvariable heating rate thermalanalysis. MTGA is the third technique(patented techniques Hi-Res TGA™ &MDSC® are 1st and 2nd) to apply variableheating rate technology. MTGA is based onTGA kinetics work pioneered by Dr. JosephFlynn of NBS.

Modulated TGA delivers simultaneousweight loss and kinetic analysis without

the time and singledecomposition

mechanismlimitations ofthe traditionaltechnique. MTGA,like it’s predeces-sor MDSC,superimposes

a sinusoidaltemperature

modulation on thetraditional linear

heating profile.

Just as it does in MDSC,the application of a sinusoidal

temperature program producesa change in the response of the testspecimen. In MTGA it is the rate ofweight loss that responds to the temperatureoscillations. The measurement of the rateof weight loss provides an experimentaltool to study the kinetics of decompositionor volatile reactions. The use of discrete

fourier transformation allows kineticparameters such as activation energy andpre-exponential factor to be calculated ona continuous basis. This permits the studyof decomposition kinetics as a function ofother experimental parameters such astime, temperature, and conversion.

Advantages of Modulated TGA include:• Model-free calculation of Activation Energy• Calculation of Pre-exponential Factor with

1st order assumption• Continuous measurement of Activation

Energy and Pre-exponential Factor• Increased productivity

There was substantial interest in MTGAat the NATAS conference, and developmentcontinues as we work to fully understandthe capabilities and applications of thisexciting new technique. For additionalinformation request TA publicationnumber TA-237 or contact your localtechnical representative.

Modulated TGA™

Introduced at 1997 NATAS Conference

Rheology Navigator2 & 2plus released

This much anticipated upgrade to ourpopular rheometer software began shippingas of October. Rheology Navigator 2is a 32-bit multitasking program for theWindows® 95 operating system. Continuingthe tradition of its predecessor, versions2 and 2plus have further enhanced capa-bilities and easier operation. They providepowerful direct control of a rheometer withfull automation of data generation andanalysis.

UNCOMPLICATED SCRIPT DEVELOPMENT

The use of scripts can automate allrheometer functions and may be used to

run a method repeatedly with the operatorneeding only to change samples at promptedintervals. Long or complex experimentsmay be run unattended and you have theoption of creating a library of scripts fordistribution thereby assuring the integrityof results performed at many locations byoperators of varying experience.

The new “record” mode allows ascript to be automatically generated in thebackground during normal rheometeroperation. For manual script developmentthe editor prompts the correct use ofstatements and syntax. A toolkit of basic

Rheology Navigator2 & 2plus released

(Continued on page 5)

2

Dr. Wei-Ping Panreceives NATASFellowship Award

Dr. Wei-Ping Pan, Sumpter Professor ofChemistry at Western Kentucky University(Bowling Green, KY USA), was named a Fellow ofthe North American Thermal Analysis Society atthe conference this year. The NATAS Fellowshipaward acknowledges and honors individuals whohave records of distinguished scientific achieve-ment, significant technological accomplishment,and/or outstanding scholarship in the field ofThermal Analysis.

Dr. Pan established the Thermal AnalysisLaboratory at Western Kentucky in 1986 which,under his direction and leadership, has developedinto an internationally recognized facility. Hehas published over 100 papers and lecturedinternationally on the subject of ThermalAnalysis. Recent accomplishments include hisposition as Chair of the successful NATAS ShortCourse. We join Dr. Pan’s other colleagues incongratulating him on this latest award!

Because of it’s ability to separate “total” heat flow into its heatcapacity and kinetic components, Modulated DSC™ provides uniqueinsights into polymer melting and related phenomena, including:

• separation of simultaneous crystallization andmelting processes

• more accurate measurement of the temperaturerange of melting

• increased precision of heat capacity measurements• more accurate measurement of the initial crystallinity

of polymers

The study of the melting of polymers is probably the mostcommon use of DSC. However, the application of MDSC® to themelting region is often misunderstood. Adherence to a few simpleexperimental guidelines enables us to easily apply MDSC to themelting transition, providing an increased understanding of thisevent. MDSC parameters optimized for analysis of the meltingregion are as follows:

Modulation PeriodA period between 40 to 100 seconds should be selected when

using helium as a purge gas, and 60 to 100 seconds with anitrogen purge.

Underlying Heating RateA heating rate which provides a minimum of 4-5 cycles at the

half-height of the sharpest melting peak should be selected.

Modulation AmplitudeAn amplitude which provides cyclic heating only (no cooling) and

causes the heating rate to periodically go to 0°C/min should beselected. This is done with the use of the table shown in Figure 1.

The primary reason for having the heating rate periodically goto 0°C/min is to eliminate the contribution of heat capacity to theheat flow signal. When the heating rate goes to zero, the heat capacitycontribution to the total heat flow signal also goes to zero and thispermits continuous, time-dependent processes such as crystal perfectionor crystallization to be observed in the raw, modulated heat flow signal.The heat flow at the lowest heating rate is seen along the top of themodulated heat flow signal. Hence, the top of the modulated heat flowsignal should have the same shape as the Nonreversing signal, which isthe calculated MDSC signal for time-dependent processes.

For additional information on the application of MDSC to themelting region, request TA publication number TA-227, “MeltingPhenomena in Linear Low Density Polyethylene by MDSC®”.

Melting Phenomena by MDSC®

Edith Turi honored at PittConDr. Edith Turi, was recognized by

TA Instruments for her contribution to thescience of Thermal Analysis, and for herdedication to promoting its understandingand application. Dr. Turi is course director forthe American Chemical Society (ACS) shortcourse, Thermal Analysis in PolymerCharacterization. This intensive programoffers guidance for applying thermalanalytical methods to polymer researchand production.

Attendees at the course preceding PittConthis year, marked the 1000th student to attendDr. Turi’s course, and to benefit from hertechnical guidance and personal attention.No other ACS Short Course has achieved thislevel of participation.

TA Instruments applauds this achieve-ment as just one of the many ways Dr. Turihas contributed to the education of thermalanalysts around the world.

Len Thomas, President ofTA Instruments, presenting award

to Dr. Edith Turi.

Figure 1. Maximum ‘heat only’ amplitude (°C)

2

31997 Volume 2

ImprovedApplicationsLibrary CD-RomTA Instruments is recognized as a leaderin providing after-the-sale assistance sousers receive maximum benefit from theirinstruments. One of the many ways weprovide this support is in the generationand distribution of technical applicationsliterature. In mid 1996, TA Instrumentsintroduced a CD-Rom that included a widerange of applications papers. Positiveresponse has prompted further develop-ment resulting in the release of anupdated version.The new Applications Library CD containsmany new papers, a total of 210 documentscovering a wide range of Thermal Analysisand Rheology applications. Documents areprovided in Adobe Acrobat portable documentformat for easy viewing or printing. Allnecessary software is included on the CD,and is compatible with Windows 3.1, 95,NT, OS/2, and Mac. The CD is indexed withlinks allowing easier retrieval, as well assearches by content, author, subject, titleor document number. To order the newApplications Library CD, contact yourlocal representative, or call TA Instrumentsat (302) 427-4000 and ask for Partnumber 925700-901.

AccessoriesPrice ListThe Accessories Parts andSupplies price catalog (US)is now available by calling(302) 427- 4000. A convenient referencecategorized for ease of use. Includes cost,descriptions and item numbers.

Hotline by e-mail?Today, many individuals and companiesrely on electronic communications becauseof the associated ease of delivery, organiza-tion, storage, and retrieval of information.We have begun to get request from readersinterested in receiving the Hotline viae-mail and are looking into the possibilityof distribution as an Adobe Acrobat PDFdocument. (Adobe Acrobat reader softwareis included on the Applications Library CD,or can be downloaded from the Internetat no charge) If you, or one of yourcolleagues, are interested in e-mail delivery,please respond to:

hotline@tainst.comPlease include your name, affiliation,address, phone, fax, and e-mail address sowe can insure accuracy of our records. Wewill measure the response to determine ifthis service will be offered.

T A Instruments sponsored a two-dayMDSC seminar in McLean, Virginiafollowing the 1997 NATAS* conference.

Attendance at the seminar rivaled that ofthe NATAS conference itself.

The first day of the seminar consistedof presentations by respected scientistsfrom around the world. Speakers andTopics were:

• A Temperature-Modulated DSCstudy of the melting of Polymers byProfessor Bernhard Wunderlich of theUniversity of Tennessee.

• Application of Modulated DSC tocrystallization kinetics of polymers: theapplication of the phase angle in thesemeasurements by Professor Akihiko Todaof the University of Hiroshima.

• The use of MDSC in the pharma-ceutical sciences by Prof. Duncan Craigof the London School of Pharmacy.

• New developments in the use ofMDSC to study reacting polymer systemsby Professor Bruno van Mele of the FreeUniversity of Brussels

• Application of Modulated DSCto the freeze-drying process by ProfessorSteven Nail of Purdue University.

• Latest developments in calorimet-ric analysis with scanning microscopy(CASM) and mechanothermal analysiswith scanning calorimetry (MASM) byDr. Michael Reading, inventor of Modu-lated DSC, Loughborough University ofTechnology.

The second day featured presentationsby Dr. Steve Aubuchon and Len Thomas ofTA Instruments providing training designedto help MDSC users gain maximum benefitfrom their investment. Topics includedcalibration, selecting optimum conditions,interpretation of results, sources of errorand typical applications.

TA Instruments takes seriously ourcommitment to provide superior customerservice and support after the sale. Thisseminar is an example of that commitment.Attendees were encouraged to completeseminar evaluation surveys, and feedbackwas very positive with a 98% approval rating.Almost half of the attendees commentedthat the seminar exceeded theirexpectations. Comments included:

“TA Instruments has once againdone an excellent job in theirsupport of customer training.

This seminar was one of the bestI have ever attended in my

years of scientific endeavors”Fortune 500 Polymer Scientist

The many MDSC papers and posterspresented at the NATAS conference (approx.20% of all papers/posters presented at NATASinvolved MDSC), and the response to thisseminar are evidence of the significancethat Modulated DSC™ plays in modernthermal analysis. As a scientific community,our understanding and application of MDSCcontinues to grow, encompassing a widerange of materials and applications.

*NATAS is the North American ThermalAnalysis Society. For information on NATAS,contact: The Complete Conference, Inc.,

1540 River Park Drive, Suite 111,Sacramento, CA 95815telephone (916) 922-7032

Post NATAS MDSC® Seminar anOverwhelming Success!

Dr. Michael Reading, inventor of Modulated DSC,speaks about the latest advancements to a room

packed with approximately 180 attendees.

Attendees to our post NATAS seminar gatherfor food and socializing.

3

4

•

ISO 9000

•

CE

R

T I F I CATI O

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TA INSTRUMENTS

Organizational Events

SALES ACHIEVEMENT AWARD

The Shindo Scientific Company Ltd.,Seoul Korea was presented with this beau-tiful lead crystal award for outstandingsales achievement in 1996. Shindo morethan doubled forecast sales for the year.

TA JAPAN RELOCATES

This relocation to a much largerfacility with more staff, will increaseTA Instruments capabilities in Japan.Our expanded laboratory will be veryconvenient for customers wishing to seeanalysis techniques.

TA Instruments Japan KKNo. 5 Koike Building1-3-12 KitashinagawaShinagawa-Ku, Tokyo 140, JapanPhone: 81-3-3450-0981We also have a branch sales office

in Osaka to better serve our customers inWestern Japan.

A successfulISO 9000 audit

The internationally recognized ISO9000 quality standards were established toassure customers that products andservices are provided in a manner thatsatisfies their needs. ISO prescribes a welldocumented management system whichtargets a problem, and quickly corrects theappropriate process, to eliminate it.

TA Instruments led the way inSeptember 1992 by being the 413th(current count exceeds 14,000) business inthe United States to receive certification.We are proud of this position but refuse torest upon its success. We emphasize theimportance of each individual employee toconstantly strive for improvement with thegoal of nothing less than total customersatisfaction. The benefits of this work ethichave shown themselves many times. (SeeHotline 1997 volume 1, page 4)

Internal audits are performed regularlyby our resident auditor certified by theAmerican Society for Quality. Our most recentannual audit performed by a RAB registrarfound the quality system in compliance, ashas been the case since initial certification.The receipt of this formal recognition assuresus that the necessary safeguards are inplace and provides you with the confidencethat your investment in TA Instrumentsproducts and services will deliver maxi-mum value.

Thermal Characterization ofPolymeric Materials, second edition.Edited by Dr. Edith Turi. Academic Press,San Diego, CA. Two volumes, casebound.

The fully revised and updated secondedition of this widely acclaimed workcontinues the tradition of the original book.It provides an in-depth overview of thermalanalysis by focusing on instrumentationand a wide array of applications. Thewell-coordinated chapters, written by

world-renowned authors, are replete withpractical examples and include important,previously unpublished research. Thiscomprehensive work is an invaluablereference source for chemist, engineers,physicist and other professionals involvedin research, development, production, appli-cations, characterization and evaluation ofpolymers.

Available from TA Instruments, orderas P/N 299900.001

Year 2000Compliance

Much media attention lately has beendevoted toward concern for software toproperly interpret the addition of anothercentury to their internal time keeping.

The problem originated nearly thirtyyears ago when programers began usingonly two digits to represent the year (97 asopposed to 1997). The fear is a computer’sinability to distinguish between the year2000 or 1900. Your bank’s computer forexample may suddenly interpret your loanpayment as being 100 years past due. Allmanner of data from pension benefits toprison sentences may be distorted.

Thermal AnalysisReference source available

Thermal Solutions software, suppliedby TA Instruments is in compliance withYear 2000 date guidelines. This qualitysoftware supports the date range from 1January 1980 through 31 December 2079with stored dates explicitly identifying thecentury. The software supports all manipu-lations and computations of time and date,produces the desired results, is seamless inits implementation, and requires no specialdata handling or manual intervention overthe supported range.

4

EXPANDED

LAB FACILITIES IN CHICAGO

At our office in Rolling MeadowsIllinois, you will see all the instrumentsin operation and discover what newtechnologies are available to fill yourgrowing needs. Receive a hands-onevaluation of our equipment and decidefor yourself. The office is convenientlylocated off I-90 between O’Hare airport &the Woodfield Mall. Time is money soinvest it wisely. Call today and set up yourappointment 302-427-4170.

The ShindoScientific team and Dean Kamm

export area manager

51997 Volume 2

SUBMITTED BY THE

INSTITUTE FOR APPLIED

COLLOIDTECHNOLOGY (IFAC)

The rheology of a typical cosmeticemulsion looks like Fig 1, showing a yieldpoint, shear thinning behavior, and atime-dependent structure breakdownthat results in hysteresis i.e. thixotropy.Viscosity is a strong function of shear rate(Fig 2), i.e. the processes the emulsion isundergoing (Fig 3). As a general rule, ifthe yield point, infinite [shear around1O 3 s-l] viscosity, and the thixotropy oftwo emulsions are the same, they willhave the same primary skin feel, to theextent that a testing panel cannot tell thedifference. Yield point gives the resistancethe emulsion offers before flowing.Infinite viscosity characterizes how theemulsion behaves during spreading.Thixotropy gives an indication of thedegree to which the emulsion flows intothe skin’s valleys. If structure recoveryis quick (quasi “solid” behavior), theformulation will remain on the skin’speaks, giving a greasy feel. If structurerecovery is slow (or there is no structureat all, as in a Newtonian fluid), theformulation will disappear into the skin’svalleys, giving a dry feel (Figure 4). Atintermediate thixotropies, an even,occlusive film will be formed on the skin.By understanding the relationshipbetween formulation variables and theserheological parameters, any desiredprimary skin feel can be engineered.

IFAC's standard thixotropy measure-ments can be roughly translated asbelow, but must be interpreted alongsidethe infinite (1000 1/s) viscosity values:above 200 mPas gives a greasy skinfeeling, while below 50 mPas gives a dryskin feeling.

Rheologyand Skin Feel

Thixotropy values Film formation on skin Skin feeling

-20,000 to 0 inhomogeneous greasy and tackyO to 50,000 homogeneous acceptable

50,000 to 200,000 inhomogeneous dry

RheologyNavigatorSoftwareContinued from page 1

rheometer functions and mini-scripts aresupplied which may be blended into newscripts. Any script may be run from withinanother, allowing the incorporation ofpreviously developed methods.

Navigator 2 Plus offers the addedbenefits of a debug mode allowing scriptsto be run step by step to resolve errors andensure correct operation. Also included isthe feature of conditional execution. Thispermits statements to be written that allowthe software to make intelligent decisionsbased upon operator input or the resultsobtained from a sample. Use of these state-ments within scripts allows automation ofdecisions and hence complex methodsmay be followed automatically.

INFORMATION LIBRARY

The Navigator Compendium includedwith 2 plus is an expert system that providesthe operator with access to a wealth ofrheological knowledge. The compendiumoffers help in choosing the appropriategeometry, test method or interpretation ofthe data. This may be used to developrheological knowledge and reduce thelearning curve.

“record mode” effortlesslygenerates a scriptduring normal

rheometer operationContinuing our tradition of excellence

in product innovation this upgrade raises aquality product to a higher standard.Rheology Navigator 2 and 2plus offerimproved ease of operation and morepowerful capabilities while retaining thefamiliarity and reliability you have cometo expect from TA Instruments.

To run Rheology Navigator 2 youwill need to be using Rheology Solutionssoftware and Windows® 95. For additionalinformation request TA publicationnumber RH-017 or contact your localtechnical representative.

Figure 4Impact of flow characteristics ondistribution on skin

Figure 3Shear rates (1/s) of some processes

Figure 2Dependance of viscosity of emulsionson shear-rate

Figure 1Shear-Stress and Shear-Ratebehavior of an O/W cream

Sedimentation of fine powders in liquids 10-6 - 10-4

Leveling due to surface tension 10-2 - 10-1

Mixing and stirring 101 - 103

Spraying and brushing 103 - 104

Rubbing 103 - 105

Shear Rate [1/s]

Shea

r Str

ess

[Pa]

Downcurve

Upcurve

Emulsion with solid behavior

Emulsion with newtonian behavior

log Shear Rate

log

Vis

cosi

ty

Zero Shear Viscosity

Shear Viscosity

Infinite Viscosity

6

S. AUBUCHON

The thermal treatment by which amaterial is conditioned can affect it’sprocessability, storage stability and end-use. In the area of polymeric films andfibers, a process known as “heat-setting”is often used to precondition the material.The heat-setting process involves holdingthe material isothermally at a particulartemperature for a specified time. Thisprocess imparts dimensional stability tothe material, increases wrinkle resistance,and in the case of fibers, can influenceyarn performance.

To this end, thermal analysis hashistorically been used to monitor theeffects of the heat-setting or annealingprocess. When a polymer is annealed at atemperature between the glass transition(Tg) and melt (Tm), crystalline structureis formed at the annealing temperature.On the second heat by DSC, the degree ofcrystalline structure can be monitored byinvestigation of the “middle-endothermpeak” (MEP). This peak appears as aresult of heat-setting the material, andmay be due to melting of lamellae crystalsformed during the heat set process. Theposition and size of the MEP can help todetermine the sample’s heat-set history,and can aid in process developmentand quality control. Figure 1 shows theMEP formed by annealing a sample ofpoly(ethylether)ketone at 310°C forseveral hours.

In Figure 1, the MEP appears at atemperature slightly above the heat-settemperature of 310°C, and overlaps themain melting peak of the material.

Modulated DSC™ separates thetotal heat flow signal (dQ/dt) of standardDSC into two components (equation 1);the heat capacity component (Cpb) andthe kinetic component f(T, t). In MDSC,these are referred to as the ReversingHeat Flow and Nonreversing Heat Flow,respectively.

The middle endotherm peak is akinetically-controlled event, and is well-resolved in the Nonreversing Heat Flowsignal, shown in Figure 2.

The ability of MDSC to resolve themiddle endotherm peak from overlappingevents makes it a useful tool in theanalysis of heat-set and annealingtemperatures in other polymeric systems.

High-Temperature Thermoplastic

Good quality assurance typicallyrequires constancy in processing. Occa-sionally, mechanical failures in processequipment can cause molded parts tobe subject to elevated temperatures forextended periods of time; thermal eventssimilar to heat-setting. Investigation ofthe MEPs caused by these thermal eventshelps to determine the effects on thematerial.

Figure 3 shows the MDSC of a high-temperature thermoplastic material froma routine molding process. The majorityof the melting is resolved in the ReversingHeat Flow signal, whereas the cold

crystallization and ongoing crystalperfection up to the bulk melt areresolved in the Nonreversing Heat Flow.

In contrast, Figure 4 shows theMDSC of the same material after aprocessing abnormality. This sample washeld at 300°C for one hour before beingcooled. The result was that the materialwas annealed at this temperature, andthe structural morphology was altered.This is apparent in the NonreversingHeat Flow signal in Figure 4. The cold

An MDSC® Study ofHeat-Set and AnnealingTemperatures

Figure 2MDSC of PEEK

annealed at 310°C

Figure 4High-Temperature Thermoplastic,

heat-treated at 300°C

Figure 1DSC of Poly(ethylether)ketone

annealed at 310°C

Figure 3MDSC of a High-Temperature

Thermoplastic (normal processing)

Equation 1

100 150 200 250 300 350 400–5

–4

–3

–2

–1

Temperature (°C)

Hea

t F

low

(m

W)

Melting Peak

Middle Endotherm Peak

exo

100 150 200 250 300 350 400–.25

–.15

–.05

.05

–.3

–.2

–.1

0

Temperature (°C)

He

at

Flo

w (

mW

)

( )

No

nre

v H

eat

Flo

w (

mW

)

( )

Rev H

eat

Flo

w (

mW

)

–.15

–.05

exo

50 100 150 200 350300250 400 450–.25

–.20

–.15

–.10

–.05

0

.05

–.20

–.15

–.10

–.05

0

–.15

–.10

–.05

0

.05

.10

.15

Temperature (°C)

Hea

t F

low

(W

/g)

No

nre

v H

eat

Flo

w (

W/g

)

Rev

Hea

t F

low

(W

/g)

Total Heat Flow

Reversing Heat Flow

Nonreversing Heat Flow

145.27°C12.62J/g

366.83°C

368.40°C

368.89°C

328.59°C46.52J/g

347.42°C42.02J/g

50 100 150 200 350300250 400 450–.25

–.20

–.15

–.10

–.05

0

.05

–.20

–.15

–.10

–.05

0

–.15

–.10

–.05

0

.05

.10

.15

Temperature (°C)

Hea

t F

low

(W

/g)

No

nre

v H

eat

Flo

w (

W/g

)

Rev

Hea

t F

low

(W

/g)

327.51°C39.36J/g

347.39°C46.91J/g

356.62°C6.075J/g

366.70°C

368.57°C

309.16°C

368.97°C

Total Heat Flow

Reversing Heat Flow

Nonreversing Heat Flow

6

71997 Volume 2

crystallization peak evident in Figure 3does not appear. In fact, no crystallizationtakes place below the annealing tem-perature of 300°C. Holding the sampleisothermal has caused the near-completecrystallization of all the material kineticallycapable of crystallizing at 300°C. Oncethe annealing temperature is surpassed,the MEP becomes apparent. This peak isassociated with the portion of the materialisothermally crystallized at 300°C, andmay be the melting of this material.Above the MEP temperature, the crystalperfection process resumes (shaded area),until the bulk melting of the material. Theeffect of thermal history on this materialis relatively easy to interpret from theNonreversing Heat Flow signal.

Polymeric Films

Polymeric films are often heat-treatedto impart a specific sample morphologyand to maximize performance. The MEPcan be used to monitor heat treatmenttemperature, and within a specificmaterial, heat treatment time at a constanttemperature. Figure 5 shows the Nonre-versing Heat Flow signals for an HDPEthin film annealed at 110°C for varyingamounts of time (30, 60, 120, 240, 480,and 960 min.). As the annealing time isincreased, the area of the initial MEPincreases, and the subsequent exothermiccrystal perfection peak is suppressed.Annealing the material at this temperaturecrystallizes the sample, which adds areato the MEP, and reduces the amount ofless crystalline material available forcrystal perfection.

A similar effect is seen in a thin filmof PET which was heat-treated in thesame fashion. As the bulk melting of PEToccurs above 200°C, and the Tg is below100°C, the sample was annealed at 150°Cfor the same duration of time. Figure 6shows a comparison of the NonreversingHeat Flow curves for the PET sample. As

the annealing time increased, thetemperature of the onset of the MEPincreases, as does the area of the MEP.

A plot of annealing time @ 150°Cversus MEP area (Figure 7) illustrates thedirect relationship.

Polymeric Fibers

PET and other polyesters are oftenspun into fibers for use in fabrics andfillers. These fibers are typically heat-treated to optimize structure and durability.The MEP as detected by MDSC is anexcellent indicator as to the specificthermal history experienced by a fibersample.

Figure 8 shows comparison of theNonreversing Heat Flow curves for a varietyof polyester fibers heat-set at differenttemperatures. The onset of the MEPindicates the temperature of the heat-setting process. The relative peak area isanalogous to the degree of heat-setting.As the heat-set temperature of the fiber isincreased, the MEP onset increases inconcert. The relative equivalence in peakarea suggests that the samples havesimilar degrees of heat-set structure,applied at varying temperatures.

Summary

The middle-endotherm peak whichappears in the DSC scans of annealed orheat-set materials can be a very usefultool to investigate the specific thermalhistory applied to the material. ModulatedDSC separates the MEP into the Nonre-versing Heat Flow signal, which improvesthe resolution of this entity. Using MDSC,several polymeric samples have beenexamined, and the thermal histories ofthese samples have been extrapolatedback from the investigation of themiddle-endotherm peak.

Figure 6PET, annealed @ 150°C

Figure 8Nonreversing signals showingdetection of annealing temperaturesof PET fiber

Figure 5High -Density PolyethyleneFilm, annealed @ 110°C

Figure 7Plot showing relationship betweenMEP area and annealing time

100 105 110 115 120 125–.150

–.125

–.100

–.075

–.050

Temperature (°C)

No

nre

v H

eat

Flo

w (

W/g

)

Annealing Time30 minutes

60 minutes120 minutes

240 minutes480 minutes

960 minutes

exo

7

140 150 160 170 180 190–.040

–.035

–.030

–.025

–.020

Temperature (°C)

No

nre

v H

eat

Flo

w (

W/g

)

Annealing Times

30 minutes60

120 240480

960

exo

1 1.5 2 2.5 3.2

.6

1

1.8

1.4

log (Annealing Time) [min.]

Pea

k A

rea

(J/g

)

y=0.8038x - 0.4437R2=0.9694

40 60 80 140 180 220120100 160 200-.02

-.01

0

.03

.01

.02

Temperature (°C)

No

nre

v H

eat

Flo

w (

W/g

)

93.22°C#016

32.6J/g

#013-0.5J/g

119.18°C#018

40.9J/g 160.31°C#022

43.7J/g

179.90°C#024

49.9J/g

The TA HotlineAttn.: Jim SchilthuisTA Instruments, Inc.109 Lukens DriveNew Castle, DE 19720-2795Telephone: (302) 427-4000Fax: (302) 427-4001e-mail: info@tainst.com

BULK RATEU.S. POSTAGE

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NEW CASTLE, DE

Thermal HazardInformationrequired by US Federal regulation

Time to Thermal Runaway, CriticalTemperature, Critical Dimension andAdiabatic Decomposition Temperature Riseare figures-of-merit used to assess thethermal hazard of chemicals or chemicalprocess materials. ASTM Test Method E 1231describes how these figures-of-merit maybe calculated from DSC derived dataincluding kinetics, specific heat capacityand thermal conductivity.

According to U.S. federal regulation,companies involved in chemical manufac-turing or processing are now required tohave thermal hazard potential informationon all of their process materials. This meansthat many organizations, which were notformerly concerned about hazard potential(because their processes are considered tobe safe), now need to initiate programs toobtain this information.

TA Instruments suppliesanalysis software for calculation

of these importanthazard potential parameters

The TA Instruments Thermal SolutionsDSC Thermal Stability Kinetics softwarepackage includes these calculations as partof the program.

Copies of E 1231 may be ordered directlyfrom ASTM by calling (610) 832-9585 orby writing to ASTM Customer Service,100 Barr Harbor Drive, West Conshohocken,PA 19428-2959. Each copy will be priced atabout 20 US dollars.

May ’97 witnessed an achievementwith the shipping of our 100thDMA 2980. This significant

event, coming only seven monthsafter the shipment of the first 2980, is amilestone worthy of celebration.

The high customer demand forthis improved design is a creditto those members of thedevelopment team whomade it possible. We wouldbe remiss, however, not toacknowledge the excellenteffort extended by themanufacturing team whoturned this successfuldesign into reality. Prelimi-nary reports expect this tobe the most successfulproduct introduction in thehistory of TA Instruments.

An evening celebration of finedining was held to commemorate theevent. The festivities included presentationof a personalized framed photo of theinstrument and team for all employeeswho participated in making the DMA asuccess. Speakers that evening includedLen Thomas, the president of TA

Instruments.

Most of all we wish tothank our customers. It isyour insistence for qualitythat fires our imagination.The DMA 2980 representsthe culmination of yourneeds and our commit-ment to satisfy them.

100th DMA 2980

the DMA development team

Select members of thedevelopment team shownwith the 100th DMA.

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