PCT Engineered Electron Beam Effects on Polymers - Manual

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Electron Beam Effects on Polymers
By Dr. Steve Lapin
March 10, 2010
Here is a summary of the effect of electron beam processing on some common materials used in the
converting industry:
• Elastomers such as natural rubber, polybutadiene, and SBR: Most will undergo crosslinking.
• Polyethylene (LDPE, LLDPE, HDPE) and polyethylene copolymers such as EAA and EVA:
Crosslinking; used for shrink films and physical property enhancement.
• Polypropylenes (BOPP): Chain scission can give a slight degradation in mechanical properties.
This does not usually affect the functionality of the film at typical cure dose levels.
• Fluoropolymers: PTFE (Teflon) is degraded by EB. Little effect on PVDF at normal cure doses.
• PVC: Degraded by EB. Properties may still acceptable at normal cure doses. Films will
yellow. Color is easily visible in a roll but may be usable when viewing a single layer of film.
• Polyester (PET): Very resistant to EB effects.
• Polyamides (Nylon): Little effect on mechanical properties at typical cure dose levels. Color
may be formed which fades and disappears in a few hours.
• Polystyrene: Very resistant to EB effects.
• Polysiloxanes (silicones): Will undergo crosslinking.
• Paper (cellulose): Chain scission. Some discoloration and off-odor may occur depending on the
grade of paper that is used. Paper is widely used in EB converting without problems.
Notes:
• “Normal cure dose” means up to about 50 kGy. Some polymers are treated at much higher
levels to intentionally induce crosslinking or scission effects.
• Atmosphere (air or nitrogen) can influence the effect EB will have on polymers.
• Polymer additives such as antioxidants and fillers can influence the effect EB will have on
polymers.
• The crystallinity of a polymer can influence how it will be affected by EB.
• The temperature of the polymer during irradiation can also influence the effect EB will have.
Additional recommended reference: “Physical Properties of Polymers Handbook”, James E. Mark
editor, ISBN 0387312358, Published by Springer, 2
nd edition 2006.