Polyme Analysis 2010 Part 12 pps

ü Examine surface irregularities or fracture areas in a part for plastics applications.ü Measure the thickness in cross section of thin coatings.. Fourier Transform Infrared Spectrometry

ü Examine surface irregularities or fracture areas in a part for plastics applications.

ü Measure the thickness (in cross section) of thin coatings

üStudy surface topography and failure analysis

üTest specimens are sputter coated with gold, then placed in a vacuum chamber for viewing on the computer monitor at up to 10,000x magnification

ü Polaroid photos are taken for a permanent record Approximately 0.25" x 0.25"

Polaroid photos can be scanned into electronic documents

Scanning Electron Microscopy (SEM)

Untreated jute NaOH-treated jute

NaOH/PAPS-jute

PP/jute composite without treatment

PP/jute composite with treatment

Fourier Transform Infrared Spectrometry (FTIR)

-ASTM E1252

-Identify of polymer

-Detect organic layers or fiberglass

-Detect surface coatings

-Also examine contaminants and some fillers within the polymers

-A small amount (few grams) of sample is needed

-Three basic spectrometer components:

+Radiation source

+Interferometer (giao thoa kế),

+and detector

Simplified optical layout of a typical FTIR spectrometer

Fourier Transform Infrared Spectrometry (FTIR)

-The sample is inserted into a detector and the amount of Infrared Light absorbed

at each frequency is determined

The most commonly used interferometer is a Michelson interferometer

üConsists of 3 active components: a moving mirror, a fixed mirror, and a beamsplitter üThe two mirrors are perpendicular to each other

üThe beamsplitter is often made by depositing a thin film of germanium onto a flat KBr substrate

üRadiation from the broadband IR source impinges on the beamsplitter

ü At the beamsplitter, half the IR beam is transmitted to the fixed mirror and the remaining half is reflected to the moving mirror

üAfter the divided beams are reflected from the two mirrors, they are recombined at the beamsplitter Due to changes in the relative position of the moving mirror to the fixed mirror, an interference pattern is generated

üThe resulting beam then passes through the sample and is eventually focused on the detector

Fourier Transform Infrared Spectrometry (FTIR)

Wavenumber ( ):

=1 / λ

['gæmə]

['reidiou] ultraviolet

Infrared Region(IR)

electromagnetic spectrum

λ

c

h hν

The energy of the wave (E):

ν: frequency

λ :wavelength

The infrared region (14,000 cm-1 to 10 cm-1): near, mid and far-infrared region

üMid-infrared region (4,000 cm-1 to 400 cm-1):

→the most interest region

→corresponds to changes in vibrational energies within molecules

üThe far infrared region (400 cm-1 to 10 cm-1):

→useful for molecules containing heavy atoms such as inorganic compounds

→requires rather specialised experimental techniques

FTIR

Symmetrical stretching

Asymmetrical stretching

In-plane bending

Out- of -plane bend

Molecular Vibrations

Major vibrational modes for a nonlinear group, CH 2

Stretching vibration

Bending vibration

Out-of-plane bending

(When a compound absorbs the energy of Infrared radiation)

FTIR

Single Bonds to Hydrogen

FTIR