I have recently done a DMA test using the same machine.

Young's modulus is referred to as tensile modulus, which is totally different material property other than the storage modulus. The storage modulus refers to how much energy was stored by the material when subjected to oscillating loads.

Did you use the tension modulus in your test?

I disagree with the Youssef in some points. His definition for the storage modulus is absolutely true and all the physical issues and responses of a sample is originated from the structural features of materials (viscoelastic nature for polymers) in the solid state.  Therefore, tensile modulus is not conceptually too much different from the storage modulus in the solid state. In DMA tests performed by using of tension geometry, test specimen is subjected to very small strains at a constant frequency and each strain step reveals a stress. Modulus is simply related with the stress and strain in a particular conditions. Most DMA equipments enable to convert the data (creep data) to stress-strain. You can check the relationship between the tensile modulus to storage modulus of your sample by performing a short-term creep test and doing SS conversion.

Hello Ali, Thanks for your comment. I mentioned that tensile modulus and storage modulus are two different material properties. I think we both agree on that.

In case of doing DMA tests in tension mode, the material is subjected to repeated tensile forces, which resembles doing several tensile tests and accordingly relates storage modulus and tensile modulus. On the other hand, doing DMA tests in different loading modules will probably result in more divergence between tensile and storage moduli values.

Young modulus is the bulk property of the sample being tested. Its is defined by the rate of rate and the direction of the strain applied . The strain is towards the center then compression behaviour is observed hence compression modulus, when the strain is moving away for the strain, its creates elongation hence its called tensile modulus, the strain is applied on one surface while the other surface is fixed at tis position then shear force experienced leading to shear modulus.

Young's modulus describes tensile elasticity is the tendency of an object to deform along an axis when opposing forces are applied along that axis 

Now if the strain is applied sinusoidal as in with DMA,  along the asis, the definition of Stress and corresponding changes. Also, DMA is mainly used to test material with viscoleastic behavior. This material exhibits elastic and viscious compenent of the sample/The applied stress is sinusoidal hence corresponding strain will be sinusoidal. If a material is purely elastic such as silicon tube, then the stress and strain will overlap giving storage modulus. If the material have viscous component such as elastomer the modulus will be shown in to values i.e storage and viscous.

Also, one must remember the methods to test the tensile modulus is based on the assumption that the material deformation is opnly due to it is elasticity while DMA is based on the principle that when the material deforms , its due to the combination of the elastic and viscous components.

Hence, even if a purely elastic materials are tested, the storage modulus cannot be called as elastic (even though many people take freedom in calling it the same) due to the application of the stress, corresponding deformation and also due to the  method of  modulus 

Storage modulus is the energy which you get back after applying certain force to any sample. The amount lost is called loss modulus. In this measurement various modes are used bending tensile and few more. In the measurement load is applied and sample is allowed to relax back. Usually single frequency is used. There are also time-temperature superposition (WLF).

Other case `tensile modulus', is the application of constant load and is usually applied till it breaks. The sample has no/least scope  to relax.

Dear Supriya,

I found as very interesting your question and also I have appreciated the answers already received by you! I would like only to comment some aspects that can help more or less.

Traditionally, we are determining the tensile/ modulus of elasticity (also known as elastic modulus or Young’s modulus) of various polymeric materials (specimens made by injection or other techniques,  films, sheets, etc.) using specific standards. However, it is generally known that many factors could be determinant in the measuring with high accuracy of Young’s modulus (speed of testing/ a low speed is more indicated, form of specimens, etc.) thus it is necessary to give the correct information about the conditions of testing, to specify if it was used or no an extensimeter, etc.

I will say that the utilization of specific standard for films (e.g. ASTM D882, the Standard Test Method for Tensile Properties of Thin Plastic Sheeting) can be even more indicated.

But your question is about DMA Q800….According to TA Instruments you can work in “Controlled Force/Strain Rate Mode”. “In this mode, the temperature is held constant while stress or strain is ramped at a constant rate. This mode is used to generate stress/strain plots to obtain Young’s Modulus.” (http://www.tainstruments.com/pdf/literature/TA284.pdf).

According to the great part of answers already received, due to the differences between methods it is assumed to have dissimilarities between the storage and Young’s modulus values, both determined using DMA. But you can do this comparison if it is required, don’t forget to do the comparison for a similar temperature!!

Finally, I believe that this communication (Determination of the mechanical properties at elevated temperature for a PP homopolymer applying tensile tests and DMA measurements, see you http://research.fh-ooe.at/files/publications/2201_APST2_2011_Poster_Puehringer.pdf). The conclusion of authors is that at elevated temperature for polypropylene (PP) the curve of the flexural storage modulus shows a good correlation to the Young’s modulus determined by tensile testing.

Good luck in your research and best regards,

Marius

http://www.tainstruments.com/pdf/literature/TA284.pdf

http://research.fh-ooe.at/files/publications/2201_APST2_2011_Poster_Puehringer.pdf

Thank you all for your answers, you have been so helpful!

Thank you so much for your detailed answer!

During my researches, I found some additional relevant information, where Menard states that the storage modulus is ideally equivalent to Young's modulus, which is not actually true as (E) is calculated using data ranges for stress and strain, while E' comes from almost one point. Morover, the testing procedure for each of the properties are totally different.

You can refer to Section 5.2. Chapter 5 - Dynamic Mechanical Analysis: A Practical Introduction by Menard for more information.

Best of luck