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Determination of bromine content in polyolefin brominated flame retardants
2017-12-2 11:56:39
Determination of bromine content in polyolefin brominated flame retardants
The main factors affecting the full combustion of brominated flame retardants and the full absorption of the components to be tested were studied from the aspects of sample size, combustion improver and absorbent. The influence of potentiometric titration parameters, titration operation process and electrode performance on bromine flame retardants bromine content determination accuracy was discussed. In order to ensure the accurate and reliable results of the determination of bromine content in polyolefin brominated flame retardants, the corresponding measures are put forward to different influence factors.
Oxygen flask combustion is one of the simplest methods for the determination of bromine content in bromine flame retardant, and is a semi micro and micro analytical method. The determination of bromine flame retardants in polyolefin is similar to other samples. The accuracy of the results is influenced and restricted by various factors such as sample pretreatment process, potential titration parameter, artificial operation process and electrode performance in the instrument.
The oxygen flask combustion process has the characteristics of simple operation process, convenient equipment manufacture, short processing period, batch processing of samples and less interference from matrix. The specific operation process of determination of bromine content of brominated flame retardant polyolefin: 500 mL iodine flask, by sintering a spiral platinum wire fixed on the bottle stopper; will be accurately weighed samples in ash free filter paper, to wrap the sample clip on th; adding absorption liquid and oxygen filled in iodine flask, bag filter and tail light samples quickly add iodine flask to the full combustion. try
The organic halogen in the sample will form halogenated hydrogen and free halogen. It is absorbed by dilute solution of sodium hydroxide.
The absorption solution is determined by silver nitrate standard titration solution, and the halogen content is determined by potentiometric titration. The accuracy of the potentiometric titration in general and with high precision, the current widely used automatic potentiometric titration. The titration end point more quickly and accurately, improve the repeatability of measurement results and the accuracy, reduce the human error, the complex automatic titration procedure. The following focuses on the effects of sample pretreatment, potential titration parameters, operation process, electrode performance and other factors on the measurement results.
The purpose of sample pretreatment is to make brominated flame retardant bromine content determination of polyolefin more simple and fast, and the results of the tested components can truly reflect the properties of samples. Before sample processing, we must study whether there are interference components in the sample pretreatment method, so as to reduce the factors that affect the measurement results in the process of sample operation. The bromine content in brominated flame retardants was determined by oxygen flask combustion potentiometric titration. The following 4 aspects should be noticed when using oxygen flask combustion to treat high bromine content samples.
Triphenyl Phosphate (TPP)
Retardants tpp quality standards:
Appearance: white flaky crystal
Content : ≥ 99%;
Acid value (mgKOH / g): ≤ 0.1;
Free phenol : ≤ 0.1%;
Freezing point : ≥ 47.0 ℃
Chromaticity (APHA): ≤ 60;
Moisture : ≤ 0.1%
Density (50 ℃, g/cm3) :1.185-1 .202
Retardants tpp Packing: NW 25KG / composite paper ( lined with black plastic bags ) , a small cabinet loaded 12.5 tons .
Flame retardant TPP has many advantages, such as excellent transparency, softness, bacterial resistance, and water proof, grease-proof, good electric insulation, as well as good compatibility. Flame retardant TPP is mainly used as the flame-retardant plasticizer for cellulose resin, vinyl resin, natural rubber and synthetic rubber. And it may also be used as the flame-retardant plasticizer for glyceryl triacetate thin ester and film, rigid polyurethane foam, phenolic aldehyde resin, and PPO, etc.
Flame retardant TPP is a kind of halogen-free environment-friendly flame retardant with phosphorus element. Most of the products in the market are self-colored flaky crystal, our product is self-colored crystalline powder, and is more soluble in organic solvents. TPP is not soluble in water, but soluble in benzene, chloroform, ether and acetone, and slightly soluble in Z alcohol. Flame retardant TPP is nonflammable with slight aromatic odor and slight deliquescence. The fusion point is about 50 ℃, and fast melts to hoop-shape when heated. The lubricate effect is excellent, and it is often used as the flame retardant plasticize lubricant. What is more, it is used as the flame retardant for many plastics and resins, such as phenolic aldehyde resin, epoxy resin and so on.
(1) weigh the sample. Brominated flame retardants due to high bromine content in the sample, the combustion is more difficult, but the total amount of oxygen iodine flask restricted basic does not burn bottle capacity adjustment. Therefore, under the premise of ensuring the accuracy of measurement, minimizing the amount of sample and the smaller the amount of sample, the more sufficient the combustion is. If the amount of sample is more, the combustion of the sample is not enough, the decomposition will be more incomplete. For the 500 mL iodine flask samples, preferably not more than 15 mg. Because the sample size is very small, it is easy to result in large measurement uncertainty. Therefore, the performance of the balance is very important. The accuracy of the balance is the prerequisite to ensure the accuracy of the measurement results. The weighing sample needs to use more than 1/100000 precision balance, preferably using one million parts of the precision balance to reduce the weighing error.
(2) combustion supporting agent. The oxygen flask combustion method is used to treat bromine flame retardant. The key of this method is whether the sample can burn and decompose completely. In order to ensure the accuracy and reliability of the test results, the samples are fully burned and absorbed completely. Bromine flame retardants have high bromine content. The samples treated by the general oxygen flask combustion method are incomplete, and the tested components in the samples can not be fully decomposed. The results are quite different from the actual values.
The combustion state of the sample can be improved and the combustion temperature of the sample can be improved by adding the combustion supporting agent, so as to guarantee the complete decomposition of the components to be measured. The specific operation is to add some can produce high accelerant in filter paper bag package samples, such as long chain alcohols ethylene glycol with higher hydrogen content, so as to generate heat and hydrogen in the combustion with the sample, can ensure the sample in the combustion component to be measured completely decomposed. If the residue is still found in the absorption liquid after burning, the sample is not completely decomposed, and the sample must be reburned.
(3) absorption fluid. Because of brominated flame retardants in combustion decomposition in generating hydrogen bromide, also generates bromate and a small amount of free bromine absorption liquid, sodium hydroxide does not absorb bromate and free bromine, resulting in low measurement results, by increasing the absorption of liquid components to improve the absorption efficiency of analytes. Specific measures: adding hydrazine or sodium hydroxide in the absorption of hydrogen peroxide reducing agent has very strong reducing ability of liquid, can make bromate and completely free bromine was reduced to bromide.
Hydrazine hydrate or hydrogen peroxide has very strong reducing power, and excessive interference to measure the titration end point group. So the selected hydrazine hydrate or hydrogen peroxide as reducing agent and sodium hydroxide solution composed of absorption liquid, can significantly improve the absorption liquid measuring components absorption treatment, guarantee the accuracy and reliability of measurement results.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
The main factors affecting the full combustion of brominated flame retardants and the full absorption of the components to be tested were studied from the aspects of sample size, combustion improver and absorbent. The influence of potentiometric titration parameters, titration operation process and electrode performance on bromine flame retardants bromine content determination accuracy was discussed. In order to ensure the accurate and reliable results of the determination of bromine content in polyolefin brominated flame retardants, the corresponding measures are put forward to different influence factors.
Oxygen flask combustion is one of the simplest methods for the determination of bromine content in bromine flame retardant, and is a semi micro and micro analytical method. The determination of bromine flame retardants in polyolefin is similar to other samples. The accuracy of the results is influenced and restricted by various factors such as sample pretreatment process, potential titration parameter, artificial operation process and electrode performance in the instrument.
The oxygen flask combustion process has the characteristics of simple operation process, convenient equipment manufacture, short processing period, batch processing of samples and less interference from matrix. The specific operation process of determination of bromine content of brominated flame retardant polyolefin: 500 mL iodine flask, by sintering a spiral platinum wire fixed on the bottle stopper; will be accurately weighed samples in ash free filter paper, to wrap the sample clip on th; adding absorption liquid and oxygen filled in iodine flask, bag filter and tail light samples quickly add iodine flask to the full combustion. try
The organic halogen in the sample will form halogenated hydrogen and free halogen. It is absorbed by dilute solution of sodium hydroxide.
The absorption solution is determined by silver nitrate standard titration solution, and the halogen content is determined by potentiometric titration. The accuracy of the potentiometric titration in general and with high precision, the current widely used automatic potentiometric titration. The titration end point more quickly and accurately, improve the repeatability of measurement results and the accuracy, reduce the human error, the complex automatic titration procedure. The following focuses on the effects of sample pretreatment, potential titration parameters, operation process, electrode performance and other factors on the measurement results.
The purpose of sample pretreatment is to make brominated flame retardant bromine content determination of polyolefin more simple and fast, and the results of the tested components can truly reflect the properties of samples. Before sample processing, we must study whether there are interference components in the sample pretreatment method, so as to reduce the factors that affect the measurement results in the process of sample operation. The bromine content in brominated flame retardants was determined by oxygen flask combustion potentiometric titration. The following 4 aspects should be noticed when using oxygen flask combustion to treat high bromine content samples.
Triphenyl Phosphate (TPP)
Retardants tpp quality standards:
Appearance: white flaky crystal
Content : ≥ 99%;
Acid value (mgKOH / g): ≤ 0.1;
Free phenol : ≤ 0.1%;
Freezing point : ≥ 47.0 ℃
Chromaticity (APHA): ≤ 60;
Moisture : ≤ 0.1%
Density (50 ℃, g/cm3) :1.185-1 .202
Retardants tpp Packing: NW 25KG / composite paper ( lined with black plastic bags ) , a small cabinet loaded 12.5 tons .
Flame retardant TPP has many advantages, such as excellent transparency, softness, bacterial resistance, and water proof, grease-proof, good electric insulation, as well as good compatibility. Flame retardant TPP is mainly used as the flame-retardant plasticizer for cellulose resin, vinyl resin, natural rubber and synthetic rubber. And it may also be used as the flame-retardant plasticizer for glyceryl triacetate thin ester and film, rigid polyurethane foam, phenolic aldehyde resin, and PPO, etc.
Flame retardant TPP is a kind of halogen-free environment-friendly flame retardant with phosphorus element. Most of the products in the market are self-colored flaky crystal, our product is self-colored crystalline powder, and is more soluble in organic solvents. TPP is not soluble in water, but soluble in benzene, chloroform, ether and acetone, and slightly soluble in Z alcohol. Flame retardant TPP is nonflammable with slight aromatic odor and slight deliquescence. The fusion point is about 50 ℃, and fast melts to hoop-shape when heated. The lubricate effect is excellent, and it is often used as the flame retardant plasticize lubricant. What is more, it is used as the flame retardant for many plastics and resins, such as phenolic aldehyde resin, epoxy resin and so on.
(1) weigh the sample. Brominated flame retardants due to high bromine content in the sample, the combustion is more difficult, but the total amount of oxygen iodine flask restricted basic does not burn bottle capacity adjustment. Therefore, under the premise of ensuring the accuracy of measurement, minimizing the amount of sample and the smaller the amount of sample, the more sufficient the combustion is. If the amount of sample is more, the combustion of the sample is not enough, the decomposition will be more incomplete. For the 500 mL iodine flask samples, preferably not more than 15 mg. Because the sample size is very small, it is easy to result in large measurement uncertainty. Therefore, the performance of the balance is very important. The accuracy of the balance is the prerequisite to ensure the accuracy of the measurement results. The weighing sample needs to use more than 1/100000 precision balance, preferably using one million parts of the precision balance to reduce the weighing error.
(2) combustion supporting agent. The oxygen flask combustion method is used to treat bromine flame retardant. The key of this method is whether the sample can burn and decompose completely. In order to ensure the accuracy and reliability of the test results, the samples are fully burned and absorbed completely. Bromine flame retardants have high bromine content. The samples treated by the general oxygen flask combustion method are incomplete, and the tested components in the samples can not be fully decomposed. The results are quite different from the actual values.
The combustion state of the sample can be improved and the combustion temperature of the sample can be improved by adding the combustion supporting agent, so as to guarantee the complete decomposition of the components to be measured. The specific operation is to add some can produce high accelerant in filter paper bag package samples, such as long chain alcohols ethylene glycol with higher hydrogen content, so as to generate heat and hydrogen in the combustion with the sample, can ensure the sample in the combustion component to be measured completely decomposed. If the residue is still found in the absorption liquid after burning, the sample is not completely decomposed, and the sample must be reburned.
(3) absorption fluid. Because of brominated flame retardants in combustion decomposition in generating hydrogen bromide, also generates bromate and a small amount of free bromine absorption liquid, sodium hydroxide does not absorb bromate and free bromine, resulting in low measurement results, by increasing the absorption of liquid components to improve the absorption efficiency of analytes. Specific measures: adding hydrazine or sodium hydroxide in the absorption of hydrogen peroxide reducing agent has very strong reducing ability of liquid, can make bromate and completely free bromine was reduced to bromide.
Hydrazine hydrate or hydrogen peroxide has very strong reducing power, and excessive interference to measure the titration end point group. So the selected hydrazine hydrate or hydrogen peroxide as reducing agent and sodium hydroxide solution composed of absorption liquid, can significantly improve the absorption liquid measuring components absorption treatment, guarantee the accuracy and reliability of measurement results.
Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd
http://www.yaruichem.com
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