聚合物中复合材料动态机械热分析检测方案(流变仪)

智能文字提取功能测试中

Application NoteV-241 Dynamic Mechanical Thermal Analysis(DMTA) on Polymer Composites with theHAAKE MARS Rheometer Frits de Jong and Klaus Oldorp， Thermo Fisher Scientific， Process Instruments， Karlsruhe， Germany Introduction For many modern technical appli-cations， polymer composites are thematerials of choice because their pro-perties like e.g. specific strength，chemical resistance and shape can betailored to the individual application.The production process involvesembedding fibres or fibre fabrics ina liquid polymer matrix. Subse-quently， to control this process， therheological characterization of theliquid matrix is a must. To test themechanical properties of the finalcomposite is at least difficult if notimpossible with classical rheologicalsetup. Due to the high hardness andsmooth surface of many composites，samples are difficult to shape andoften slip after being put betweenparallel plates. To extend its range of testing methodsinto the field of composites， theThermo Scientific HAAKE MARScan be equipped with solids clamps(Figure 1)， an accessory for its Controlled Test Chamber (CTC). Thepatented design of the CTC， whichuses a combination of radiation heat-ing and convection heating， createsa large uniform heating zone insideits gold plated test chamber (seeFigure 1) thus allowing testing largersamples under uniform temperatureconditions. Fig. 2： Left side： Schematic top view on one of the solids clamps holding the sampleperfectly centred with its 2 moving jaws (depicted in yellow). Right side： detail view ofone of the moving jaws. The solids clamps can be equippedwith special jaws for soft， mediumor hard samples. With the latterones they are even able to fix hardcomposite materials with smoothsurfaces during oscillation testing.Due to their unique design with 2moving jaws， the solids clampsautomatically position the samplein the axis of the rheometer，whichis mandatory to avoid any errorfrom eccentric placement (Figure 2). Carbon Fibre Enforced Sample The first sample was a light weightcarbon fibre enforced sample likee.g. being used in airplane construc-tion.A constant oscillation at 1 Hzin controlled deformation mode(CD) with a deformation y= 0.1 %was chosen. According to the typicaltemperature range for such an appli-cation， the sample was tested in atemperature range between -100 °Cand +240 ℃ to determine its StorageModulus G'at low temperatures andits Glass Transition Temperature T. Fig. 3： Storage Modulus G’(red)， Loss Modulus G"(blue) and tan(d) (pink) as a functionof temperature for the carbon based sample. The glass transition temperature Tisindicated by the green line. The results of 2 independent tests (light and dark colour)run on fresh samples each show the excellent reproducibility of the results. The excellent reproducibility of thetest results could be shown by com-paring the results of 2 independenttests run on 2 samples from the samematerial. The 2 sets of curves shownin Figure 3 are almost perfectlyidentical. During the measurement the ThermoScientific HAAKE MARS applied aconstant small pulling force on thesample to compensate any thermalexpansion or contraction (see blackcurve in Figure 4). Thus， the distancebetween the two clamps follows anychange in sample length. This infor-mation can be used to check whetherthe clamps were able to hold thesample or might have lost their grip.In a plot of the sample length as afunction of temperature， any slippingof the sample between the jaws of theclamps would show as a step-change.The smooth progression of theorange curve in Figure 4 documentsthe clamps’steady grip even on sucha hard sample. Apart from its diagnostic value， thedata shown in Figure 4 contains valu-able information about the sampleitself. The length decrease with increas-ing temperature reflects the negativetemperature expansion coefficient(o) some carbon fibre enforced ma-terials show in fibre direction. Weeven can see from the change inslope that the sample’s a changesaround Tc Glass Fibre Enforced Sample The temperature dependant be-haviour of two different glass fibreenforced polyphenylene-sulfid (PPS)samples has been tested in CD-modewith y=0.01 % between 30 °C and250 °C. Materials like these are usedfor applications where a high mecha-nical and thermal stability is required.So again the solids clamps wereused to be able to properly fix the samples for testing. In addition to the glass transitionof the PPS at 103 °C we see for bothsamples， a secondary maximum inG“ and tan (8) is clearly visible atapprox. 70°C for Sample A， indi-cating an additional compound inthe matrix of Sample A. This modi-fication leads to a softer behaviourof the compound material between40 °C and 100 °C. Above 100 °Cboth materials show similar pro-perties. 48.65 2.0 Carbon Sample 01一Fn=f(T) 48.60 E48.55- 48.50 1.51.00.510 N/y-0.5-1.0-1.5 48.45 -2.0 -80 0 80 160 240T/'C Fig. 4： Constant normal force (black) and decreasing sample length (orange) duringa temperature increase from -100 °C to 240°C on the carbon fibre enforced sample. Fig.5： Storage Modulus G' (red)， Loss Modulus G" (blue) and tan(8) (pink) as a functionof temperature for 2 different glass fibre enforced PPS samples (light and dark colour).The glass transition temperature TG is indicated by the green line. Fig. 6： Constant normal force (black) and increasing sample length (orange) during atemperature increase from 30 °C to 250 °C on one of the glass fibre enforced PPSsamples. Regarding the sample length overtemperature confirms also in thiscase the perfect grip of the ThermoScientific HAAKE MARS solidsclamps. Compared to the carbonfibre enforced sample， these sampleshave a positive thermal expansioncoefficient， which does not changearound T. From the data in Figure6 a constant coefficient of approx.o=3.3×106K1 can be calculated. The special design of the ThermoScientific HAAKE MARS'solidsclamps combines easy handling withhigh precision and perfect reproduci-bility of the testing results. Differentcomposite samples with very hardand smooth surfaces have been testedgiving very good results.Using the rheometer’s lift and normalforce sensor in combination providesan easy way to verify the perfect gripon the sample and thus the reliabilityof the data collected. Due to theunique precision of both lift andnormal force sensor， important dataabout the thermal expansion of thesamples can be collected simultane-ously. This allows e.g. the calculationof the sample’s thermal expansioncoefficient. With its Controlled Test Chamberand its solids clamps， the HAAKEMARS is able to extend its range oftesting capabilities into the field ofdynamic mechanical thermal analysis(DMTA). In combination with aclassical rheological setup like e.g. aPeltier temperature control andcone/plate geometries the HAAKEMARS is the perfect and cost efficientsolution for testing polymer com-posites and their liquid base materialson one instrument. Process Instruments International/Germany Dieselstr. 4. 76227 Karlsruhe Tel. +49(0)721 40 94-444 info.mc.de@thermofisher.com Benelux Tel.+31 (0) 76 5 87 98 88 info.mc.nl@thermofisher.com ChinaTel. +86 (21) 68 65 45 88info.mc.china@thermofisher.com France Tel.+33 (0) 1 60 92 4800 info.mc.fr@thermofisher.com IndiaTel. +91 (20) 66 26 7000info.mc.in@thermofisher.com Japan Tel. +81 45 453 9167 info.mc.jp@thermofisher.com United KingdomTel. +44 (0) 1606 54 81 00info.mc.uk@thermofisher.com USA Tel. 603 436 9444info.mc.us@thermofisher.com www.thermoscientific.com/mc V-241_0.09 Thermo S CIENTIFIC For many modern technical applications, polymer composites are thematerials of choice because their properties like e.g. specific strength,chemical resistance and shape can betailored to the individual application.The production process involvesembedding fibres or fibre fabrics ina liquid polymer matrix. Subsequently, to control this process, therheological characterization of theliquid matrix is a must. To test themechanical properties of the finalcomposite is at least difficult if notimpossible with classical rheologicalsetup. Due to the high hardness andsmooth surface of many composites,samples are difficult to shape andoften slip after being put betweenparallel plates