Chain extender acetoxylation of ethylene diamine modification effect

Chain extender acetoxylation of ethylene diamine modification effect, from the infrared spectra of synthetic product as you can see, in about 1652 cm - 1 has a strong absorption peak, corresponding to the C = O stretching vibration, namely amide band.

Band at 3292 cm 1 is the stretching vibration free of N - H, 3087 cm - 1 band is form hydrogen bonding, association of N - H stretching vibration, all into unimodal, instructions for secondary amide; 1556 cm - 1 band is N - H bending vibration, strength, very characteristics, namely the amide; 1289 cm - 1 band is C - N stretching vibration, namely amide band. According to the presence of these characteristic peak, can be concluded that the chemical formula which best characterizes the synthetic product for H3COCHN (CH2) 2 nhcoch3, chemical structure in line with expectations.

The determination of nitrogen content. Product of synthetic nitrogen measured 19. 39%, ethylenediamine and ice acetic acid reaction might be the following 3 kinds of product, its chemical formula respectively H3COCHN nhcoch3 (CH2) 2, (H3COC) 2 n (CH2) 2 nhcoch3 (H3COC) 2 n (CH2) 2 n (COCH3) 2, the theory of nitrogen content of 19 respectively. 44%, 15. 05%, 12. 28%. And measured values is 19. 39%, and 19. Close to 44%, so can be concluded that the chemical formula which best characterizes the synthetic product for H3COCHN nhcoch3 (CH2) 2. Nuclear magnetic resonance hydrogen spectrum analysis.

Using 1 h-nmr the synthetic products were characterized, synthetic products of 1 H nuclear magnetic resonance spectra as you can see, the modified with ethylenediamine acetoxylation of proton resonance absorption peak appears. In the chemical shift = 3. 10 (s, 4 h), as the original ethylenediamine two hydrogen absorption peaks of methylene, in = 1. 78 (s, 6 h), as on two acetyl methyl hydrogen absorption peak, and D2O - NH - active hydrogen peak in = 4. 65 overlap. 1 H nuclear magnetic resonance spectra analysis is further evidence that the result of the synthetic product for diacetyl ethylenediamine, its chemical structure is CH3OCHNCH2CH2NHCOCH3.

The chain extender reactivity determination. The type of chain extender, the active also have very big distinction, select the appropriate chain extender can control gel time. This system USES two amine chain extender, generally speaking if chain extender amino on the electron-withdrawing groups, it is easy to give active H +, this kind of chain extender is relatively lively; If amino pick up on the rich electronics group is good for the stability of H + on amino, so will weaken the activity of diamine class chain extender. The activity of chain extender and the molecular structure of the whole diamine and space steric factors also have certain relations.




Chinese name: Diethyl toluene diamine(DETDA)

Diethyltoluenediamine Uses:

The product is identical to Ethancure 100 and Lonza DETDA 80, DETDA is very effective polyurethane elastomer chain extender; also be used as polyurethane and epoxy resin curing agent, epoxy resin of an antioxidant, industrial oils and lubricants . In addition, also as intermediates in organic synthesis.Especially for the RIM (reaction injection molding), is important in the field of spray polyurea chain extender species. Also can be used for casting polyurethane elastomer (CPU) and a curing agent, epoxy curing agent, epoxy resin of antioxidants, lubricants and industrial oils other antioxidants.


According to the D - 2000 = 73 (mass ratio), chain extension agent NCO index of 1. 05, calculate drug dosage, measured the gel time of ethylene diamine extender chain agent system of 4. 6 s, and, in the same situation with diacetyl ethylenediamine extender chain of polyurea gel time is 53 s. The experimental results show that using the diacetyl ethylenediamine as chain extender, can greatly reduce the reaction rate of polyurea, extend the gel time.

Ethylenediamine simple space steric small molecular structure, amino on the activity of H + is very big, and modification of new chain extender diacetyl ethylenediamine, - COCH3 structurally replaced the original structure of active H atoms, and increased the steric hindrance effect, and - COCH3 for electronic group, thus reducing its reactivity, prolong the gelation time.

Through the methods of acyl ethylene diamine and ice acetic acid reaction to generate new amide blocking the diacetyl ethylenediamine chain extension agent, and through the study of the melting point, ir, nitrogen content of products and hydrogen nuclear magnetic spectrum analysis to determine the structure of products, and concluded that the product is the diacetyl ethylenediamine, on the structure of two - COCH3 replaced the original structure of the two active H atoms. Effect test shows that modified amide chain extender can significantly reduce the polyurea synthetic reaction activity.

For 2 amine chain expanding agent, such as MOCA, urea, etc., due to containing four active hydrogen, it and diisocyanate reaction form of urea key-value NHCONH - and polar groups and also contains two active hydrogen, can form a double hydrogen bond, secondary crosslinking, form more than two alcohols chain extender dense mesh structure, so it can greatly improve the crosslink density of propellant and the tensile strength, and secondary crosslinking keys too dense increase the crosslink density is too large (such as M0CA extender chain of propellant crosslinking density than the blank was increased by more than 2 times) indeed reduce the elongation.

Actually contains four active hydrogen of diamine extender chain agent ACTS as a crosslinking agent. For diamino diphenyl ether, may be because of ether bond p electron cloud on the oxygen atoms and two conjugate benzene, increase the negative charge of benzene ring, which reduces the -n ~ base activity and curing reaction slowly, propellant mechanical properties reduced.

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