Spherulite (polymer physics)

In <a href="/facts/Polymer_physics/01sWSKtL">polymer physics</a>, spherulites (from Greek sphaira = ball and lithos = stone) are <a href="/facts/Spherical/jywYLNM2">spherical</a> <a href="/facts/Crystallinity/qA9S1duu">semicrystalline</a> regions inside non-<a href="/facts/Branching_(polymer_chemistry)/KYF9YA1j">branched</a> linear polymers. Their formation is associated with <a href="/facts/Crystallization_of_polymers/hLNR2u5c">crystallization of polymers</a> from the melt and is controlled by several parameters such as the number of nucleation sites, structure of the polymer molecules, cooling rate, etc. Depending on those parameters, spherulite diameter may vary in a wide range from a few micrometers to millimeters. Spherulites are composed of highly ordered <a href="/facts/Lamella_(materials)/GtQ7hVIA">lamellae</a>, which result in higher density, hardness, but also brittleness when compared to disordered regions in a polymer. The lamellae are connected by amorphous regions which provide elasticity and impact resistance. Alignment of the polymer molecules within the lamellae results in <a href="/facts/Birefringence/J4lLuR3a">birefringence</a> producing a variety of colored patterns, including a <a href="/facts/Maltese_cross_(optics)/SbsQ3Ium">Maltese cross</a>, when spherulites are viewed between crossed <a href="/facts/Polarizers/kPDwyboP">polarizers</a> in an <a href="/facts/Optical_microscope/5700vcna">optical microscope</a>.

Spherulite (polymer physics) open-in-new

Spherulite (polymer physics)