Mechanically gradient polymers

Polymer gradient materials (PGM) are a class of <a href="/facts/Polymers/eF32E50K">polymers</a> with gradually changing mechanical properties along a defined direction creating an <a href="/facts/Anisotropic/YMqTQWVB">anisotropic</a> material. These materials can be defined based upon the direction and the steepness of the <a href="/facts/Gradient/TsR7uukj">gradient</a> used and can display gradient or graded transitions. A wide range of methods can be used to create these gradients including gradients in reinforcing fillers, <a href="/facts/Cross-link/zeQ9hEAA">cross-link</a> density or porosity to name a few. <a href="/facts/3D_printing/lbvWU3t0">3D printing</a> has been used to combine several of these methods in one manufacturing technique.
These materials can be inspired by nature where mechanical gradients are used commonly to improve interfaces between two dissimilar surfaces. When two materials that have different moduli are connected together in a bilayer, this can create a weak junction, whereas a mechanical gradient can reduce the stress and strain of the connection. In contrast, a <a href="/facts/Butt_joint/pSSpVGz5">butt joint</a> that gives a junction between materials with little to no gradient has been shown to be weaker than the homogenous components.
Mechanically gradient polymers are not manufactured as extensively as can be found in nature, and there can also be unintended gradients during the manufacturing process. Materials are not always completely uniform despite the intentions of the manufacturer, and these unintended gradients may weaken the material rather than improve. Therefore, mechanical gradients must be properly applied to the particular application to prevent introduction of instabilities.

Mechanically gradient polymers open-in-new

Mechanically gradient polymers