Editing Polymer (section)

===Mechanical properties===
[[File:Stable neck MDPE.jpg|upright=0.5|thumb|right|A polyethylene sample that has [[necking (engineering)|necked]] under tension]]
The bulk properties of a polymer are those most often of end-use interest. These are the properties that dictate how the polymer actually behaves on a macroscopic scale.

====Tensile strength====
The [[tensile strength]] of a material quantifies how much elongating stress the material will endure before failure.<ref>{{cite book|author-link=M. F. Ashby|last1=Ashby|first1=Michael|last2=Jones|first2=David|title=Engineering Materials|url=https://archive.org/details/engineeringmater01jone|url-access=limited|pages=[https://archive.org/details/engineeringmater01jone/page/n199 191]–195|publisher=Butterworth-Heinermann|year=1996|edition=2|isbn=978-0-7506-2766-5}}</ref><ref>{{cite book|first1=M. A.|last1=Meyers|first2=K. K.|last2=Chawla|title=Mechanical Behavior of Materials|publisher=Cambridge University Press|year=1999|page=41|url=http://www.toodoc.com/Mechanical-Behavior-of-Materials-ebook.html|isbn=978-0-521-86675-0|access-date=31 December 2018|archive-url=https://web.archive.org/web/20131102010325/http://www.toodoc.com/Mechanical-Behavior-of-Materials-ebook.html|archive-date=2 November 2013|url-status=dead}}</ref> This is very important in applications that rely upon a polymer's physical strength or durability. For example, a rubber band with a higher tensile strength will hold a greater weight before snapping. In general, tensile strength increases with polymer chain length and [[cross-link|crosslinking]] of polymer chains.

====Young's modulus of elasticity====
[[Young's modulus]] quantifies the [[elasticity (physics)|elasticity]] of the polymer. It is defined, for small [[deformation (mechanics)#Strain|strain]]s, as the ratio of rate of change of stress to strain. Like tensile strength, this is highly relevant in polymer applications involving the physical properties of polymers, such as rubber bands. The modulus is strongly dependent on temperature. [[Viscoelasticity]] describes a complex time-dependent elastic response, which will exhibit [[hysteresis]] in the stress-strain curve when the load is removed. [[Dynamic mechanical analysis]] or DMA measures this complex modulus by oscillating the load and measuring the resulting strain as a function of time.