PC-ABS: Polycarbonate Material Properties

PC-ABS is a blend of the two polymers - polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) - and it includes the benefits (and limitations) of both thermoplastics. PC-ABS materials are widely popular in the engineering world for their functional characteristics.

This article will explore what makes PC-ABS an attractive engineering thermoplastic by detailing its desirable properties, its uses, and its unique attributes from other materials.

The tensile strength of a material is the stress level at which the material goes from deforming elastically to plastically. In other words, the tensile strength denotes at what point the material will permanently deform. This value is important when specifying a material for structural applications, where the tensile strength must never be surpassed. PC-ABS has a good tensile strength of 5,900 psi/ 41 MPa, being lower than PC but higher than ABS.

The tensile modulus of a material is defined as the ratio of its tensile strength to its strain when undergoing elastic (non-permanent) deformation. Also known as Young’s modulus or the modulus of elasticity, the tensile modulus describes the stiffness of a material or its ability to return to its original shape under stress. While not precisely elucidating by itself, the tensile modulus is used in calculations to predict how much a material will extend under tension or shorten under compression. PC-ABS has good stiffness, giving it good dimensional stability and creep resistance as well as better machinability than either polymer alone.

Tensile elongation defines how stretchy a material is. Also sometimes referred to as elongation at break, it describes the amount of stretching as a percentage of the stretched material length to its original length. Tensile elongation describes both elastic and plastic deformation of a material, where it is the sum of all possible elastic and plastic deformation. Large tensile elongation values represent ductile, gummy materials, while very small tensile elongation values represent brittle, crack-prone materials. PC-ABS has a good tensile elongation at 6%, showing it is flexible yet stiff enough to not be overly ductile.

Flexural strength is defined at the maximum stress point in which a material plastically bends (or snaps) in a 3-point flexure test. It is a general descriptor of how bendy a material is and is useful for structural applications where a material experiences forces perpendicular to its operating axis. The flexural strength of PC-ABS is good at 9800 psi / 68 MPa, making it ideal for snap-fits, jigs, and other bending components.

Flexural modulus defines a material’s ability to bend elastically and is virtually the same as the tensile modulus (just in a flexural loading arrangement and not in a tensile arrangement). It is another measure of stiffness and will help predict how much a material deflects in a structural/constant loading situation. Flexural modulus is a useful measure for materials that do not fracture easily upon applied stress (like plastics), as they generally have more bending capacity than brittle or stiff materials.

IZOD impact strength is a single-point test in which the impact strength and toughness of a material can be determined. A pendulum with a specific weight on its end will swing down and strike a specimen of a material, and the loss of energy of the pendulum plus the fracturing characteristics of a material are used to set values on impact strength and toughness. Notched vs unnotched IZOD impact strength refers to the specimen and if it has a stress-concentrating notch machined into it prior to testing. PC-ABS has great impact strength, having significantly higher values than both PC and ABS.

What Are the Usage Areas of PC-ABS?

The increased strength characteristics of PC-ABS make it a versatile engineering material. It is commonly employed in functional prototyping, as designers can freely work on the material, color it, and rely on its strength. It also has a good finish, allowing prototypes to better show what the final product will look and act like. Two industries where PC-ABS excels are the automotive and electronics industries, where it is used to make interior car components, glove boxes, seat backs, TV frames, computer housings, phone housings/cases, portable handheld device enclosures, and much more. PC-ABS can even extend into other industries with the inclusion of fiberglass and other additives to improve its resistances and mechanical properties.  

PC-ABS is also finding uses in 3D printing, as both PC and ABS are massively popular in FDM and other additive manufacturing applications. PC-ABS combines both the workability and strength of its constituents in 3D printing, and provides a more functional, attractive, and strong part.

What is the Difference Between PC-ABS and ABS?

PC-ABS is a blend of both PC and ABS, while ABS is a blend of acrylonitrile (a polymer), butadiene (a rubber), and styrene (a polymer). PC-ABS does not have the weaknesses of ABS, mainly the heat intolerance. It is also generally stronger and easier to machine than ABS and provides higher impact resistance. In general, PC-ABS is up to 60% stronger than ABS in specific blends, having higher overall mechanical properties in most categories.

Is PC-ABS Used in Plastic Injection Molding?

Yes, PC-ABS offers great plastic injection molding results. Its increased dimensional stability, heat tolerance, shrink rate, and flow characteristics make it a valuable injection-molded material when compared to its constituent polymers. It is also a fully sustainable and has an overall better performance than PC and ABS. The only major consideration for PC-ABS in injection molding is it must be dried (below 0.04% humidity) to be effectively molded.