PHÂN TÍCH POLYME ( POLYME ANALYSIS )

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Is a branch of polymer science dealing with analysis and characterisation of polymers. üThe complication of macromolecular chains, the dispersion in molecular weight, tacticity, crystallinity, orientation, composition of polymers etc. and complex morphological systems ⇒ analysis of polymer ≠ the small organic materials ⇒ Focus on viscoelastic properties, dynamic mechanical testing. Methods of polymer analysis Chemical, Molecular and Structural Characterisation -Molecular weight determination, -Microstructural characterisation and compositional analysis, -Crystallinity, -Investigation of polymer morphology, particle size, -Contact angle and wettability measurements Instruments FT-IR IR-microscope GPC ( size exclusion chromatography SEC) -Viscosimetry -X-ray (WAXS and SAXS) -EM, SEM, TEM, AFM -Dynamic and static methods...

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TRƯỜNG ĐẠI HỌC BÁCH KHOA ĐÀ NẴNG KHOA HOÁ ♣♣♣ PHÂN TÍCH POLYME (POLYMER ANALYSIS) TS. Đoàn Thị Thu Loan
Polymer analysis üIs a branch of polymer science dealing with analysis and characterisation of polymers. üThe complication of macromolecular chains, the dispersion in molecular weight, tacticity, crystallinity, orientation, composition of polymers etc. and complex morphological systems ⇒ analysis of polymer ≠ the small organic materials ⇒ Focus on viscoelastic properties, dynamic mechanical testing.
Methods of polymer analysis Chemical, Molecular and Structural Surface Mechanical and Physical Characterisation Characterisation Properties -Molecular weight determination, -Surface roughness, -Tensile, flexural, impact, -Microstructural characterisation and -Chemical compression, hardness tests, compositional analysis, composition, -Rheological and viscoelastic -Crystallinity, -Interface properties, stiffness and -Investigation of polymer morphology, modulus, surface tension, characetrisation particle size, permeation and diffusion in -Contact angle and wettability polymers, adhesion tests, measurements density Instruments -AFM, SEM FT-IR Instron mechanical tester • • • IR-microscope -FT-IR Vicker hardness tester • • • GPC ( size exclusion chromatography -Pull-out test DMA • • • SEC) Melt flow indexer • -Viscosimetry Torsions Rheometer • • -X-ray (WAXS and SAXS) • • -EM, SEM, TEM, AFM • -Dynamic and static methods for contact • angle measurements.
Methods of polymer analysis Electrical and Optical Thermal Behaviour Miscellaneous (hon tap) Properties Conductivity, electric -Melting point, glass transition Purity and molecular current in solution, temperature, free rotation temperature, weight of small light emitting and -Degradation and stability behaviour of molecules, water content electromagnetic polymers in organic solvents, surface tension properties measurement, pH Instruments Inolab conductivity GC Thermogravimetric analyser (TGA) • • meter pH meter TGA-FTIR coupled technique • HPLC • • • Differential scanning calorimetry (DSC) Karl-Fischer titration • • Modulated differential scanning • calorimetry (ADSC) Dynamic thermomechanical analyser • (DMTA) Dielectric relaxation •
Purpose of polymer analysis -For quality control -For predicting service performance -To generate design data -To investigate failures Essential to identify the purpose of testing, because the requirements for each of the purposes are different. -Complexity -Precision Balance of these attributes, -Automated test -Reproducibility according to the purpose of -Nondestructive test -Rapidity the test -Cost
Quality Control Tests üNondestructive methods are advantageous and indeed essential when 100% of the output is being tested. üThe tests should be simple and inexpensive, and automation will probably aid the rapidity of testing. üTests related to product performance are preferred.
Tests Predicting Product Performance üThe most important factor is that the tests relate to service conditions and to aspects of product performance. üshould not be too complex, although rapidity and cheapness are less important than was the case with quality control. üNondestructive tests are not always appropriate when predicting product performance, as it may be necessary to establish the point at which failure occurs.
Tests for Producing Design Data üUsually test pieces are of a simple shape and a specified size, whereas the product may be of a different geometry and size üData must be presented in a form that enables the designer to allow for changes in geometry, time scale, etc.. which implies detailed and comprehensive understanding of material behavior üIt follows that data of this type are expensive to produce and that results are unlikely to be obtained with great rapidity. üHowever, automation may be advantageous, particularly in the case of tests running for a long time (creep tests)
Tests for Investigating Failures üSome understanding of the various mechanisms of failure is necessary before suitable tests can be chosen. ü Tests need not be complex but must be relevant Ex: a simple measurement of product thickness may establish that there has been a departure from the specified design thickness. üThe absolute accuracy of the test may not be important, but it is essential that it be capable of discriminating between the good and the bad product.
What are our expectations of polymer materials? Mechanical and Physical Properties •Excellent Characteristics: Thermal Behaviour Electrical and Optical Properties •Safe to use Surface and interface Characteristics •Light weight •Reliable, durable •Low cost •Less adverse environmental impact •Good resistance to environmental attacks
Mechanical Testing of Polymers
Types of Mechnical Tests (h) (i) Flexural test (d) (e) (f) Tensile test (a) Impact test (h) (i) Compression test (b) Shear (g)
Tensile test Scope: üMeasure the force required to break a specimen and the extent to which the specimen stretches or elongates to that breaking point. üProduce a stress-strain diagram, which is used to determine tensile modulus. üThe data is often used to specify a material, to design parts to withstand application force and as a quality control check of materials. üSince the physical properties of many materials (especially thermoplastics) can vary depending on ambient temperature ⇒ test materials at temperatures that simulate the intended end use environment.
Tensile test Specimen Size: üThe most common specimen for ISO 527 is the ISO 3167 Type 1A multipurpose specimen. üASTM D882 uses strips cut from thin sheet or film. *The multipurpose test specimen: +150 mm long, +The center section: 10 mm wide *4 mm thick *80 mm long. b W δ l A tensile dog bone specimen
For the composite samples Longitudinal test Transverse test
Tensile test Test Procedure: üSpecimens are placed in the grips and pulled until failure. üFor ASTM D638, the test speed is determined by the material specification. üFor ISO 527 the test speed is typically 5 or 50mm/min for measuring strength and elongation +and 1mm/min for measuring modulus. ü An extensometer is used to determine elongation and Tensile2.wmv tensile modulus.
Stress –Strain Behavior Characteristics of stress-strain behavior: ü Modulus of elasticity (stiffness, elastic • modulus, Young’s modulus) is the slope of Stress, σ σy σF the stress-strain curve in the elastic region ü Yield strength (σy) is the stress applied to a material that just causes permanent E deformation εy εF 0 2% ü Tensile strength (TS) is defined at the Strain, ε fracture point and can be lower than the = δ/l yield strength ü Ultimate tensile strength is the stress that corresponds to the maximum load ü Elongation at break (%ε) – the increase in length of a specimen under tension before P= Applied load A = Original cross-sectional area it breaks (Strain).