Analysis of the effective content of the hottest m

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Analysis of effective content of modified CTBN products

due to the trouble of CTBN prepolymerization, in order to facilitate the promotion and use of products, many enterprises are exploring the production of etbn

the so-called modified CTBN is actually a professional CTBN prepolymerization. Its principle is that under the condition of nitrogen filling and the action of a certain catalyst, CTBN and epoxy resin react separately first, and the reaction ends until the acid value in the system does not decrease

CTBN as a raw material is required, especially the acrylonitrile content, because the nitrile group has heat resistance, oil resistance and corrosion resistance, and good bonding properties. In addition, the higher the acrylonitrile content, the stronger its compatibility with epoxy. On the other hand, the higher the acrylonitrile content, the higher the viscosity of CTBN products. Therefore, it is difficult to have both viscosity and performance

the connection reaction between CTBN and epoxy requires conditions, and the principle of this reaction is very simple. Here, take CTBN with an acrylonitrile content of 26% as an example, the average molecular weight of the product is 3150. If the two ends of the product are connected with a terminal carboxyl group (the molecular weight of COOH is 45), then the molecular weight of nitrile rubber in the product is 3150- (45*2) =3060, and the corresponding content is about 97%. Taking bisphenol A with molecular weight of 336 and epoxy equivalent of 170 and containing two epoxy functional groups as an example, if the prepolymerization result is very ideal, that is, the reaction ends after two carboxyl ends are connected to a bisphenol a molecule, then the molecular weight of the polymer will become 3150+ (336*2) =3822. Since it is a new material, the determination of epoxy value is based on the oxygen content in the product, There are four epoxy groups in this polymer (two of which are opened due to polymerization), the equivalent molecular weight is 4*43=172, the epoxy value of the product is 172/3822=0.045, and the epoxy equivalent is 2222

if the more epoxy molecules polymerized at both ends of CTBN, it is obvious that the epoxy value will begin to increase and the corresponding epoxy equivalent will decrease. Therefore, if the prepolymerization result is reflected in the polymer, it is the epoxy value. The smaller the value, the more average the polymerization, and the better the prepolymerization effect

try to calculate the polymerization results of two epoxy molecules polymerized at both ends of CTBN molecule: the molecular weight of the polymer is 4494, the epoxy value is 344/4494=0.077, and the epoxy equivalent decreases to 1307

because the molecular weight of epoxy exceeds 1/10 of CTBN, when the epoxy value of polymer increases, the molecular weight of etbn also increases rapidly. In the above two polymerization results, the total market share of nitrile rubber in etbn is more than 90%, and the content changes as follows:

ctbn 3060/3150=97%

etbn-1 3 has high stability, convenient operation Features such as simple protection 060/3822=80%

etbn-2 3060/4494=68%


it can be seen that even if the molecular content of etbn remains unchanged, the content of nitrile rubber decreases significantly, because the molecular weight of polymer increases (3) universal testing machine can not do both tensile and zigzag experiments at the same time, but the corresponding content of nitrile rubber remains unchanged, so that the proportion of BNR in the whole molecule decreases significantly

the following table lists the change process of epoxy value and epoxy equivalent:

epoxy equivalent corresponding to polymer epoxy value


etbn-1 0.045 2222

etbn-2 0.077 1307

etbn-100.174 575

the above analysis results are for reference only

in addition, the effective content of chx100 etbn is 100%, and the epoxy value of the product is 0.0625. These analyses are mainly to help customers design formulas. (end)

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