Anisotropy - Thermoplastic polymers, elastomers and additives

The molded thermoplastic materials having different properties in the flow direction compared to the direction of the transverse flow (90 ° perpendicular to the flow direction) are "anisotropic" materials. Anisotropy is the tendency of a material to present a difference in the value of its properties depending on the direction in which they are measured. Applied to a laminate, when the properties in directions parallel to the length and width thereof differ, or when the property in the direction parallel to the thickness does not coincide with those of lamination. Anisotropy occurs when the polymer chains are oriented in the direction of flow. They are usually called oriented polymer is the strictest terms an anisotropic non-linear viscoelastic material. The anisotropy of materials is more pronounced in crystalline solids, due to their regular molecular and atomic structure. In Physics, anisotropy is the ability to have properties with different values ​​when measured along axes in different directions.

Isotropy ((opposite of Anisotropy)): Independence of the mechanical properties of the direction in which they are measured. Thermoplastic materials that always exhibit the same behavior regardless of the direction of injection are "isotropic" materials. Amorphous polymers are generally isotropic, such as pC, ABS, PMMA etc.

An orthotropic material has three planes perpendicular to each other that have elastic symmetry. A materiale è ortotropo is ¨ caratterizzato da proprietà meccaniche or termiche uniche and indipendenti nelle tre direzioni reciprocamente perpendicolari. Alcuni esempi di materiali ortotropi sono il legno, molti cristalli and i metalli placcati.

Some factors such as wall thickness, injection speed, melting temperatures and mold temperatures are some variables that affect the anisotropy. Depending on the processing conditions and design of the mold, most thermoplastics exhibit a degree of anisotropy. Most glass fiber composites in injection molding are "anisotropic" materials. In fact fiberglass rende are "anisotropic" any thermoplastic materials.