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Polycarbonate is commonly used in eye protection, as well as in other projectile-resistant viewing and lighting applications that would normally indicate the use of glass, but require much higher impact-resistance. Polycarbonate lenses also protect the eye from UV light.
Although single layer polycarbonate sheeting is more flexible than polycarbonate in twinwall configuration, it still retains significant advantages over alternative materials, including glass. A typical 6mm sheet has a density of 0.72 g/cm^2 [ 6 ] and a thermal insulation R value of 0.3 m^2°C/W, while allowing 80% of visible light pass through ...
As done in crystalline materials, particles can be added to semi-crystalline polymers to change the mechanical properties. In crystalline materials the addition of particles works to impede dislocation motion and strengthen the material. However, for many semi-crystalline polymers particle fillers weaken the material.
Also mechanical properties are closely linked to the thermal stability. Based on the properties of the standard plastics some improvements of mechanical and thermal features can already be accomplished by addition of stabilizers or reinforcing materials (glass and carbon fibers, for example) or by an increase in the degree of polymerization ...
Time-independent plastic flow in both single crystals and polycrystals is defined by a critical/maximum resolved shear stress (τ CRSS), initiating dislocation migration along parallel slip planes of a single slip system, thereby defining the transition from elastic to plastic deformation behavior in crystalline materials.
Low molecular weight PTMC is a rubbery polymer with poor dimensional stability, tackiness, and inadequate mechanical properties. Nevertheless, high molecular weight amorphous PTMC (over 100,000) is very flexible, with a relatively low elastic modulus (5–7 MPa) at room temperature, tough and it presents excellent ultimate mechanical properties.
For example, polycarbonates are highly resistant to impact, while polyamides are highly resistant to abrasion. Other properties exhibited by various grades of engineering plastics include heat resistance, mechanical strength, rigidity, chemical stability, self lubrication (specially used in manufacturing of gears and skids) and fire safety.
A polycarbonate is an oxocarbon dianion consisting of a chain of carbonate units, where successive carbonyl groups are directly linked to each other by shared additional oxygen atoms. That is, they are the conjugate bases of polycarbonic acids , the conceptual anhydrides of carbonic acid , or polymers of carbon dioxide .