Higher temperatures lead to lower young modulus of the material. Weak points of every polymeric material are the secondary bonds between molecules of your polymer. With increasing temperatures, the molecules have more kinetic energy, thus the weak secondary bonds have less and less effect. With temperature high enough, the secondary bonds let go and you get molten polymer.

How much does the temperature effect your polymer depends on the material you are using and the degree of cristalinity of the material. The more cristalinic material is, smaller is the effect of the temperature until you get of course to the melting temperature. Highly amorphic (uncristalinic) materials lose the value of Young modulus at lower temperatures. The important temperature with amorphic materials is the glass transition temperature at which the Young modulus starts to decline significantly.

Hope that helps.

Jernej

Young modulus decrease at higher temp.

The answer by Jernej is correct. However, I think you cannot tackle any polymer related problems without reading some basic textbook on polymer science.

Indeed, the basic knowledge of polymers is fundamental in 3D printing.

Thank you Jernej Lenkič, Karar Abdali and Alberto D'Amore for pay attention on my question but I mean to say printing temperature in FDM technology, not only temperature. I am elaborating my question again. Let say, I have printed few parts at various liquefier temperature values. After printing parts, tensile test is being performed at room temperature then how it will affect the tensile strength, young modulus and elongation%?

Please, can you specify which polymer are you working on?

However, the mechanical properties of polymers are strongly dependent on the thermal history (indeed, I mean the cooling rate) to which they have been subjected.  In principle, the higher the printing temperature the faster the "cooling rate" to room temperature. Due to the accumulation of free volume, in amorphous polymers higher cooling rates give rise to more ductile materials with slightly lower moduli.

Higher cooling rate may also reduce the the crystallinity of semi-crystalline polymers, and this may decrease the moduli.

Thank you, Sir, I am working on the Ethylene-vinyl acetate (EVA) and the melting point of this material is about 84 Degree C. 

Sir Could you suggest me some literature work on this ?

Modulus of both entangled and cross-linked polymers reduces with temperature. If one increases the temperature from below Tg the polymers pass from frozen state to rubbery state and modulus decreases. In frozen state the polymer molecules do not much motion but only small vibrations and have high modulus. As the temperature increases they acquire higher kinetic energy leading to rubbery state and further reduction in modulus and with further increase in temperature modulus reduce the till it is melted.

(1) A. Rudin, and P Choi, “ Chapter 4 – Mechanical Properties ofpolymer solids and liquids”,Elem. Polym. Sci. Eng. (Third Ed.) pp 149-229, 2013. (2) D. J. Yarusso, “13- Effect of rheology on PSA performance”,

Adhesion Science and Engineering”, 1, 499-533, 2002

Dr. B R Gupta, Retd. Prof. I I T Kharagpur, India