CS231795B1 - Method for determining epoxide groups - Google Patents

Abstract

The invention falls within the field of macromolecular] chemistry. It concerns the determination of epoxy groups bound to powdered isotactic polypropylene with a content of 0.5 to 2.0% by weight of epoxy oxygen. The essence of the method according to the invention is that 1 part by weight of powdered isotactic polypropylene reacts with 0.3 to 0.4 parts by weight of a substance containing in the molecule a mobile hydrogen atom bound to a nitrogen or sulfur atom, preferably succinimide, 2-mercaptobenzthiazole or diethanolamine in an environment of 3.6 to 4.8 parts by weight of organic solvents, preferably n-heptane, of dioxane, dimethylformamide or their mixture, occurs in the presence of 0.02 to 0.4 parts by weight of a catalyst, which is a tertiary amine, for 2 to 5 hours at a temperature of 90 to 100 CC. The weight gain on the polypropylene powder and/or bound nitrogen, sulfur is determined.

Description

231795 8

The invention relates to a method for determining epoxidic groups.

Quantitative determination of epoxide groups is one of the most difficult tasks in organic analysis. The major complication is due to the high reactivity of this functional group, allowing the reaction associated with the opening of the epoxide ring, skidding to form carboinyl functionalities, the formation of enols or polymers, respectively. other reaction products resulting from primary premenepoxide functional group products. Conducting the epoxide functionality to be used for its quantitative determination usually requires extensive optimization of assay conditions.

Methods for determining epoxide groups in polymers are in most cases based on the addition of hydrogen halide, the most commonly used hydrogen chloride or in pyridinium chloride or ipyridinium perchlorate naepoxide group in aqueous medium. Sodium thiosulphate, sodium sulfite or periodic acid are also used as reagents. most often titration, possibly with turbidimetric measurement. Excess reagent that has not reacted is determined by the direct method. One solution is to use physical or physico-chemical instrumental methods to determine. The determination of the epoxy-functional groups bound to the polymers has its specific features, especially when the polymers are solid, although adsorption phenomena occurring on the superficial phase are present.

These drawbacks are overcome in the process of determining epoxide groups of the invention bound to an isotactic polypropylene powder containing 0.5 to 2.0 percent by weight of epoxy oxygen, wherein 1 weight percent of isotactic polypropylene powder is reacted with 0, From 3 to 0.4 parts by weight of a hydrogen-containing mobile nitrogen-containing molecule, preferably succinimide, 2-mercapto-benzothiazole or diethanolamine, in the range of 3.6 to 4.8 parts by weight of organic solvents, preferably n-heptane, dioxane, dimethylformamide or mixtures thereof, in the presence of 0.02 to 0.04 parts by weight of a catalyst which is a tertiary amine, for 2 to 5 hours, a temperature of 90 to 100 ° C, and the epoxide group is determined from an isotactic powder weight gain. polypropylene and / or bound nitrogen or sulfur content determined by elemental analysis Powdered isotactic polypropylene having a content of 0.5 to 2.0 wt. The epoxide is obtained by seeding low-oxidized polypropylene with 2,3-epoxypropyl methacrylate in an aqueous emulsion at 30 ° C to activate the reaction with divalent iron chelate.

The method of the invention makes it possible to obtain accurate results over time courses of polymer reactions, exhibiting a decrease in the content of epoxide groups, respectively. their origin.

Epoxically functional groups can react under certain conditions with mobile hydrogen-containing substances as described in MS. AO No. 218 602

pp-CH-CH + HX xoz Substances with extraordinary mobile hydrogen can be used to quantitatively determine epoxide functional groups attached to isotactic polypropylene powder. The substance used must, for the sake of unambiguous interpretation, have one movable hydrogen capable of bonding to the epoxide group, and it is useful to use it in molar prevalence. Agents such as succinimide, 2-mercaptiobenzothiazole and diethanolamine have been shown to be suitable.

Their effect may be enhanced by the addition of a catalytic amount of a tertiary amine which shortens the time required to determine and reduces the reaction temperature. The solvent used is intended to mediate contact of the agent with the surface of the polymer. The determination temperature is determined by the stability of the epoxide functional group and is chosen so that no other reactions occur. It is preferred to make the determination in an inert atmosphere, such as under nitrogen.

-PP-CH-CHX i

OH The result of the assay was calculated from the weight gain of the sample after washing and drying, therefore the reagents used must be of sufficiently high molecular weight to allow the sample weight to be readily identifiable. The presence of a precisely defined amount of nitrogen or sulfur in the reagent also makes it possible to verify the result of the gravimetric analysis by elementary analysis of their content in the sample.

The method of the present invention can be used to monitor time-varying reactions by decreasing the content of epoxide functional groups in the polymer, or by the course of their formation. It is preferred to observe this in the vials in static conversion using a series of samples.

The error in the determination of the epoxide group by the methodology was comparable to that obtained in other procedures in the homogeneous phase. 231795 8

WITH

The invention is illustrated by the following examples. Example 1

In a 15 cm 3 ampoule in an inert nitrogen atmosphere, 1.0 g of powdered isotactic polypropylene containing 0.5 to 2.0% by weight of epoxy oxygen is dispensed, the agent being 0.3 g of succinimide in the binary excess over the epo- xidic groups, 5 cm 3 of a solvent mixture of 3.1 g of n-heptane and 0.5 g of dicoxane and a catalyst of 0.04 g of triethylamine.

After closing, the vial contents are mixed by shaking and the vial is placed statically in a bath. After a period of 2 to 5 hours, the tube is cooled for 3 hours and transferred quantitatively to 100 ml of methanol. After 2 hours, the solid phase is separated on a S 2 glass frit. The nanowash is washed with water and acetone, and air drying at room temperature to a constant weight. From the weight gain of the sample, the amount of bound reagent, calculated per mol number, is given simultaneously with the number of moles of epoxide oxygen in 1 g of the sample being examined. Multiplying this figure by 1600 yields% by weight of epoxy oxygen in the sample. The result is presented as the arithmetic mean of two na-independent parallel determinations.

The epoxide oxygen content is also determined by the result of the nitrogen or sulfur determination in the sample by organoanalytical procedures.

The error of the epoxide-oxygen charge determination was ± 0.7% from analysis to nitrogen content ± 1.6 ° / o, from analysis to sulfur content of ± 1.5%. The results of the other assays given in Examples 2 to 4 are shown in Table 1. Example 2

The procedure is as in Example 1 except that 0.3 g of 2-mercaptobenzothiazole and 4.8 g of dimethylformamide are metered into 1.0 g of isotactic polypropylene powder. Example 3

The procedure is as in Example 1 except that 0.4 g of 2-mercaptobenzothiazole, 0.02 g of triethylamine and 4.4 g of goylene are metered into 1.0 g of isotactic polypropylene powder. Example 4

The procedure is as in Example 1 except that 0.3 g of diethanolamine and a mixture of 3.1 g of n-heptane and 0.5 g of di-oxane are added to 1.0 g of isotactic polypropylene powder. 231795

Conditions for the quantitative determination of epoxide oxygen in an amount of 0.5 to 2.0% by weight. bound to isotactic powder polypropylene Example Reagent Dimethyl-Catalyst Solvent Temperature Time Epoxy Determination Result (%) 0.51 ± 0.01 0.70 ± 0.01 1.20 ± 0.02 1.83 ± 0.03 Determination (hr.) CO ΙΌ CO CM at determination (° C) in O in o ω o® 03 * r-1 emitter Triethyl amine (g) CM CO <OO C3 Ti • pH forman (g) 00 '<8 _ -3 in in O 'c' tu i - 1 * * C3 0 S cv - · x tx> Λ 'ά r- (rH co co "bo CO MO θ θ' O JB 3 Ό XL> 1 Sukcínimid 2 2-mercaptobenzothiazole 3 2-mercaptobenzothiazole 4 Dietanolamine

Claims (1)

SUBJECT Method for the determination of epoxide groups bound to powdered isotactic polypropylene containing 0.5 to 2.0% by weight of epoxide oxygen, characterized in that 1 part by weight of isotactic polypropylene powder reacts with 0.3 to 0.4 parts by weight of a substance containing a mobile a hydrogen atom bonded to a nitrogen or sulfur atom, preferably succinimide, 2-mercaptobenzothiazole, or diethanolamine, in an environment of 3.6 to 4.8 parts by weight of organic solvent, preferably n-heptane, dioxane, dimethylformamide or a mixture thereof, optionally in the presence of 0.02 to 0.04 parts by weight of a tertiary amine catalyst for 2 to 5 hours at a temperature of 90 to 100 ° C and the epoxide groups are determined from the weight gain on isotactic polypropylene powder and / or the bound nitrogen content or sulfur determined by elemental analysis.