export your heat flow curve to an excel sheet. the excel sheet will have three columns of time, temperature, and heat flow mW.

divide the heat flow column by the mass to get mW/g = mJ/sec

divide mJ/sec by the heating rate ( mJ/sec / degree C/min/60 =mJ/C.g )

multiply it by the temperature interval (delta T) for the temperature you are looking at= mJ/g

this way you get J/g which is enthalpy at a certain temperature.

In order to get heat capacity at that temperature: divide by the temperature interval (J/g.K)

Compare your DSC result with a standard sample with known properties ( I used Sapphire) for my results. Check your DSC data bank, Sapphire properties must be given. 

Check the attachment.

Well, if you are using a modulated DSC then you have option to change the Y-axis from heat flow to heat capacity. 2ndly, for enthalpy you can use the instrument software to calculate the value. Good luck. 

you may follow the instruction given in this paper: 

Article Thermal behavior of cement based plastering mortar containin...

Your DSC software should be able to do that.  When superposed your curve with a baseline, you just have to compute the area below the baseline.

which DSC are you using? Mettler or TA instruments... both have softwares to do it... 

 Looking at your thermogram, time scale and temperature scale dose not match with the heating rate of  0.5 deg/min  and temperature range of 30 to 90.  Plus base line is not stable at the start of scan, you need to add isothermal step before and after the scan.

Why do you say time scale and temperature doesn't match? I see a heating rate of 0.5°C/min, He has only shown till 85°C that's about it. Use the DSC software, select the area of the peak according to the standards you have set.

I am talking about the heat signal , which is going flat around 75 deg C. 

export your heat flow curve to an excel sheet. the excel sheet will have three columns of time, temperature, and heat flow mW.

divide the heat flow column by the mass to get mW/g = mJ/sec

divide mJ/sec by the heating rate ( mJ/sec / degree C/min/60 =mJ/C.g )

multiply it by the temperature interval (delta T) for the temperature you are looking at= mJ/g

this way you get J/g which is enthalpy at a certain temperature.

In order to get heat capacity at that temperature: divide by the temperature interval (J/g.K)

@rami Saeed.....Sir,please can u explain what is temperature interval (delta T) we should consider for calculation, is it Tc - Ts?? Also, what should be the temperature interval, as it is varying throughout??

@Ashwin Raut:

mainly you multiply by Delta T to get the area over that range of temperature. So the smaller delta T you have, the more accurate you area (J/g) you get specially when your heat flow curve has a slope. 

So I would say your delta T really depends on the resolution of your data in your excel sheet. most of the DSCs can get u a resolution of 0.1C. I would say 0.5C should be enough. For example, if you look at Cp at 31C, you should take your Delta as (30.75 to 31.25) ~ =0.5 deltaT, to get the Cp value at 31C.

@Dr. Yogesh Kumar Sinha Can we choose any sample with known properties?? and in the way you mentioned do we have to use fixed mass for all samples in the study  ??

And if you have Sapphire data, please send it to me.

Regards.

@Rami Saeed

I think that we have to subtract the power ( DSC or dh/dt) loss due to heating of crucible first. In other words, we have to define a base line. 

Regards.

so what is the answer? i have a same problem like @ Ajeet Singh. i want to calculate with my mW value my work's heat capacity value but i dont do it still. how can we do it? is there any formula?

You need 3 measurements at same conditions:

1.  Baseline with 2 empty crucibles

2.  Standart with known heat capacity

3.  Your sample

Heat capacity could be deatrmined by equation:

Cp(T)= [mass(standart)/mass(sample)] * [DSC(sample)-DSC(baseline)] / [DSC(standart)-DSC(baseline)] *Cp(standart)

As shown in attached figure, there is relationship:

a = m/1000*cp *r/60*1000

thus

cp = 60*a/(m*r)

In practice, the zero line of a DSC curve is not really identifiable. Thus heat the specimen at heating rate r1 to a temperature, then cool it down at heating rate -r2. cp is determined by;

cp = 60*b/[m*(r1+r2)]

where: a (or b) heat flow (mW); m - mass of sample (mg), r, r1and r2 heating rate (oC/min). Done

Kameel Isaac

I also want to know how to calculate the rate of polymerization and double bond conversion from photo DSC results which is in terms of heat flow (W/g) as a function of time (minutes). Can someone help me.

Dear Asma I have the same problem. Could you please share it if can find out how to calculate the rate polymerization.