What is Polycarbonate?

Polycarbonate Structure and Properties

Polycarboante is a kind of polymer whose macromolecular chain is compsed of carbonate-type repeating structural units,name:polycarbonate,PC for short.It is the second largest variety of general purpose engineering plastics.  

 According to the specific composition,PC can be devided in to aliphatic group,aliphatic ring group,aromatic group three types,but only aromatic PC has practical engineering application value.  

PC is a colorless transparent (or light yellow transparent),rigid and tough material,non-toxic,tasteless,similar to the appearance of plexiglass.The performance of PC is closely related to the structural characteristics of macromolecules.

General performace:PC is transparent,yellowish or white hard and tough resin,when burning it smells like bad flowers,the falme is yellow,and has molten bubbles,extinguish once leave the fire.

Mechanical properties:the mechanical properties of PC are very good,with the advantage of stiffness and toughness.Its impact performance is one of the best of thermoplastics, three times higher than PA and POM, close to the level of PF and UP FRP.PC tensile strength and bending strength also good, and less affected by temperature.PC has better creep resistance than PA and POM and better dimensional stability.

Thermal properties: Polycarbonate has good resistance to high and low temperature, can be used in the temperature range of -130 ~ 130℃, thermal deformation temperature can reach 130-140℃, and under small load, thermal conductivity and linear expansion coefficient are relatively small, good flame retardant, belongs to self-extinguishing materials. 

Electrical properties:PC due to the weak polartiy of the polymer,its insulation performance is general.But what is valuable is that its electrical properties change little in a wide temperature range,such as dielectric constant and tangent value of dielectric loss angle almost unchanged in the range of 23-125℃.However, it should be noted that the volume resistivity of PC products increases with the increase of crystallinity.

Environmental properties: PC is resistant to organic acids, dilute inorganic acids, salts, oils, aliphatic hydrocarbons and alcohols, but not to chlorinated hydrocarbons, dilute alkali, concentrated acids, amines, ketones and lipids, soluble in dichloromethane, dichloroethane and cresol and other solvents.PC is not resistant to hot water above 60℃, long-term contact will lead to stress cracking and loss of toughness.PC uv resistance performance is not good, need to add uv absorbent, but PC resistance to air, ozone better.

Optical performance: PC is one of the optical plastics with excellent strength. Its transmittance can reach 93% and refractive index is 1.587, which is suitable for lens materials.PC as a high-end optical materials shortcomings: low hardness, poor wear resistance,so hard coating becomes very necessary to protect polycarbonate sheets from scratches,and improve their abrasion performance.