Page 4 - Solutions for Plastic Evaluation
P. 4
Evaluation of Plastic Materials
Quality Control
FTIR
Evaluation of Plastic Materials Determination of Hydroxyl Value in Polypropylene Glycol by NIR-PLS Method
Polypropylene glycol (PPG) is a liquid manufactured by polymerizing propylene glycol and is used as a raw ingredient of polyurethane.
The hydroxyl value is an index of the content of free hydroxyl groups in polyols, such as PPG. JIS K 1557 (Plastics Polyols for use in the
production of polyurethane) specifies using titration to measure the hydroxyl value. However, titration requires equipment and reagents,
and is also time-consuming. In contrast, the NIR-PLS (near infrared-partial least squares) method allows calculating the hydroxyl value easily
and quickly by simply measuring the near infrared spectrum of the sample, then using PLS to calculate quantities.
Evaluation of Raw Materials H ʢOCH2CHʣ n - OH
-
ɹɹɹɹ CH3
Structural Formula of Polypropylene Glycol
NIR spectra for four homologous types of PPG with different hydroxyl values and a calibration curve created using the PLS
Product Evaluation method are shown below. The NIR spectra indicate a difference in their peak intensities near 6990 cm and 4850 cm . The
-1
-1
peaks near 6990 cm correspond to the first overtone of the O-H stretching vibration, whereas the peaks near 4850 cm
-1
-1
correspond to a combination of the O-H stretching and bending vibrations.
1.75
Abs
1.5
Product Information 1.25 1 Corr. Coef.: 0.99996
0.75
MSEP : 0.00008
6000 5500 5000 4500 SEP : 0.00901
1/cm
NIR Spectra of Polypropylene Glycol Actual Hydroxyl Value (known concentration) vs.
Predicted Hydroxyl Value (quantitative value)
NIR Heating Transmission Cell
This cell allows measuring transmittance while liquid samples placed in the provided
6-mm diameter test tube are heated or held at a constant temperature. This is
especially convenient for quantitative analysis of multiple components in liquid
samples or when monitoring reactions during heating processes.
Specifications
• Measurement range : 12,500 to 3,800 cm -1
• Temperature range : Room temp. to 120°C
• Accessory recognition function : Included
• Test tube 6 mm dia. × 50 mm
NIR Heating Transmission Cell
4 LAAN-D-XX001A
