Mechanical properties of Xantar® polycarbonates

Grades are differentiated by molecular weight (MW) and by the addition of special stabilisers or modifications. Higher MW grades tend to have better critical strain than lower MW.

Xantar resins are stiffer than unfilled polyamides or polyesters and retain most of the stiffness up to around 100°C. The moduli of different viscosity unfilled resins do not vary. When enhanced stiffness is required, glass filled grades can be used as these can increase the modulus by up to 8 times depending on the fill content - fiber contents to 40% are offered.

Xantar polycarbonates are extremely tough and impact resistant. However, under extreme conditions, polycarbonate can still suffer brittle failure.
•  Toughness varies with molecular weight (MW) and increases as MW increases. The transition between ductile and brittle is influenced by MW. Higher MW grades are less notch sensitive and remain ductile to lower temperatures.
•  As viscosity increases with MW, processing higher MW grades becomes more difficult. Where toughness is important, the right balance between processability and impact performance has to be found. Special improved flow and toughness grades are available.
•  Where high toughness has to be combined with improved stiffness, DSM recommends Xantar G2F 23R. This 10% glass reinforced grade uses tough glass technology to maintain impact strength.

Ductile / Brittle transition of Xantar

In applications where a  part can be subjected to abrasion and wear, modified Xantar grades (with PTFE etc) are offered with reduced friction characteristics and improved wear resistance.

Xantar C– New Generation PC/ABS blends
Impact performance under extreme conditions can be improved by using blends of polycarbonate and ABS (PC/ABS blends).
•  Xantar C is a new generation of PC/ABS blends from DSM with an improved balance of flow and impact compared to traditional blends. These innovative materials represent a significant technological breakthrough and the whole property profile is improved, special features in addition to flow and impact being better heat and colour stability.

Structural foam grades can be used on larger parts (e.g. ATM fascias) where large wall thickness can be tolerated and this will give superior toughness and stiffer parts. Typical wall thickness of 6mm are used and the sandwich structure of the foamed part results in extreme toughness, stiffness and strength combination. Foamed grades also reduce sink marks.