Method for utilizing potentiometric titration method to measure polyhydric alcohol acid value
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A potentiometric titration method and potentiometric titration technology, which is applied in the direction of chemical analysis by titration method, to achieve the effect of simple method and accurate and reliable measurement results
Inactive Publication Date: 2015-09-02
SHANDONG INOV NEW MATERIALS CO LTD
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[0009] At present, there is no report on the method for de...
Method used
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Embodiment 1
[0030] The present embodiment utilizes potentiometric titration to measure the acid value of polyoxypropylene ether polyols whose Gardner chromaticity is 6:
[0031] 1. Set the titration method on the potentiometric titrator in advance, including the type, concentration, and acid value calculation formula of the titrant.
[0032] The acid value calculation formula is:
[0033] Acid value AV=V*C*56.1 / m
[0034] V: The volume of KOH-methanol standard solution reaching the titration end point, mL;
[0035] C: Concentration of KOH-methanol standard solution, mol / L;
[0036] m: weight of the sample to be tested, g;
[0037] 56.1: Molar mass of potassium hydroxide, g / mol
[0038] 2. Accurately weigh 12.5g of sample in a clean beaker, accurate to 0.01g.
[0039] 3. Add 100ml of isopropanol to the beaker, place it on a magnetic stirring table and start stirring to dissolve the sample completely, then stop stirring.
[0040] 4. Select the titration method set on the potentiometri...
Embodiment 2
[0047] The present embodiment utilizes the potentiometric titration method to measure the acid value of the aromatic polyester polyol whose Gardner chromaticity is 12 in the Gardner chroma produced with waste PET as raw material:
[0048] 1. Set the titration method on the potentiometric titrator in advance, including the type, concentration, and acid value calculation formula of the titrant.
[0049] The acid value calculation formula is:
[0050] Acid value AV=(V1-V2)*C*56.1 / m
[0051] V1: KOH-ethanol alcohol standard solution titration solution volume, mL;
[0052] V2: KOH-ethanol standard solution titration solution consumption in blank test, mL;
[0053] C: Concentration of KOH-ethanol standard solution, mol / L;
[0054] m: weight of the sample to be tested, g;
[0055] 56.1: Molar mass of potassium hydroxide, g / mol.
[0056] 2. Add 30ml of toluene-ethanol solution into a blank beaker.
[0057] 3. Set the blank titration method on the potentiometric titrator.
[005...
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Abstract
The invention relates to polyhydric alcohol value determination, in particular to a method for utilizing potentiometric titration method to measure a polyhydric alcohol acid value. The method comprises the steps of accurately weighing a polyhydric alcohol sample and utilizing an organic solvent without acid to dissolve the polyhydric alcohol sample, setting an acid value calculation formula for a potentiometric titrator, wherein an acid value AV is equal to (V1-V2)*C*56.1/M; using a potassium hydroxide-alcoholic solution to titrate the sample, enabling the potentiometric titrator to automatically stop working when a terminal point is reached, and an acid value result is given. The polyhydric alcohol contains aromatic polyester polyol prepared by raw materials including polypropylene oxide ether polyhydric alcohol, phenyl anhydride polyester polyol and waste PET and the polyhydric alcohol which needs a special assistant in a production process and accordingly cannot normally develop color in acid value determination. The problem that a titration end point is unobvious in color development and inaccurate in titration result due to deep color of a detected material and other reasons can be solved through potentiometric titration, and the method is simple, and a determination result is accurate and reliable.
Description
technical field [0001] The invention relates to the determination of the acid value of polyalcohols, in particular to a method for determining the acid value of polyalcohols by means of potentiometric titration. Background technique [0002] In the field of polyurethane polymer materials, polyol is an important chemical intermediate. During the synthesis of polyurethane, the pH of polyol directly affects the reactivity of isocyanate. The pH may also have a high or low impact on the determination of the hydroxyl value. [0003] In the synthesis process of some polyether polyols, since the use of catalysts may bring or generate alkaline substances, polyols should avoid alkaline residues to prevent many unpredictable side reactions from being promoted in the synthesis of polyurethane materials, so Measurements of pH and acidity are required to quickly determine the extent of alkaline treatment. [0004] Phthalic anhydride polyester polyols use phthalic anhydride as a raw mat...
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