Epoxy Resins and Polyurethanes example, reaction and common product? the mechanism of epoxy resin and polyurethanes?

Epoxy Resins and Polyurethanes example, reaction and common product?

the mechanism of epoxy resin and polyurethanes?

Expert Solution

Epoxy resins are resinous polymeric substances which are prepared by polymerization of 1,2- epoxide like ethylene oxide.

Poly (oxymethylene) glycols is an addition polymer and is obtained by polymerization of ethylene oxide in presence of water and sodium hydroxide as catalyst. Besides this, epoxy resin can also be prepared by reacting epichlorohydrin with bisphenol A in the presence of base.

The polymerization begins by initial attack of phenoxide ion on the epoxide ring. It opens the epoxide ring and a molecule of NaCl is eliminated in next step to regenerate epoxide ring. This molecule again reacts with NaOH to form phenoxide ion which further reacts with epichlorohydrin to form a product having epoxide group at each step. This leads to the formation of epoxy resin.

Polyurethane

Urethane is an ester of carbamic acid (R-NH-COOH). Carbamic acid being unstable decomposes to give amines and CO₂. But, the esters of carbamic acid i. e. Urethane are stable. Urethane are prepared by reaction between alcohol and isocyanate. Thus, polyurethane are condensation polymers which are prepared by reacting diol with diisocyanate. The diol can be ethylene glycol and diisocyanate used is toluene - 2,4-diisocyanate. The polyester having CH₂OH end groups can also be used as diol.

In the second reaction, ethylene glycol reacts with adipic acid forming a polyester ( by loss of water molecule). This polyester reacts with diisocyanate to form polyurethane.

queen_honey_blossom answered 2 years ago

for polyurethanes and epoxy polymers write out the relevant chemical reactions involved on polymerization and cross...

for polyurethanes and epoxy polymers write out the relevant chemical reactions involved on polymerization and cross linking. Indicate the functionality of the monomers being used.

What is the product of the following reaction and what is the mechanism?

Predict the major organic product of the following reaction and complete its mechanism below.

What is the reaction scheme and mechanism for the halogen exchange reaction, via an Sn2 mechanism,...

What is the reaction scheme and mechanism for the halogen exchange reaction, via an Sn2 mechanism, using benzyl bromide as the electrophilic substrate? In this reaction, the alkyl halide will react with sodium iodine in acetone.

Using chemical structures and a reaction mechanism to illustrate your answer, provide an example of concerted...

Using chemical structures and a reaction mechanism to illustrate your answer, provide an example of concerted acid-base catalysis in enzyme catalysis AND briefly explain why this is not possible in the absence of an enzyme.

What is the mechanism of this reaction? What type of reaction is it? What is the...

What is the mechanism of this reaction? What type of reaction is it? What is the H-NMR evidence that it has taken place?

Consider this two step mechanism for a reaction

Consider this two step mechanism for a reaction Step 1 NO2 + Cl2 ---------> ClNO2 + Cl slow; rate determining step Step 2 NO2 + Cl ---------> ClNO2 fast a. What is the overall reaction? b. Identify the intermediates in the mechanism. c. What is the predicted rate law expression? Be sure to only list reactants from the overall equation and not intermediates in the rate law expression.

1) There are two reaction mechanism for polymerization and.

1) There are two reaction mechanism for polymerization __________ and__________. 2) Stress relaxation in polymer is ________________. 3) Define HIP in ceramics processing and the advantage of the technique:_____________________________________________. 4) Common soda-lime-silica glass is made by melting together Na2CO3, CaCO3 and SiO2. Carbon dioxide will release from the process. For 1000 kg of glass with the composition of 15 wt% Na2O, 10 wt% CaO and 75% wt% SiO2, the amount Na2CO3 needed in kg is _____________ and the wt% of...

Draw the mechanism for the formation of the imine (forward reaction) and the hydrolysis of the imine (reverse reaction.)

In the reaction mechanism of chymotrypsies, formation of the tetrahedral intermediate is then followed by the...

In the reaction mechanism of chymotrypsies, formation of the tetrahedral intermediate is then followed by the formation of an acyl enzyme Intermediate. What active site residue(s) /are responsible for forming the first intermediate , and what type of catalysis occurring the first step of the reaction ?

Question