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Plasma
Treatment Improve Adhesion To Polymers
Polymeric
materials are of great interest in various biomedical
fields. For instance, acrylic polymers are applied as
prosthetic materials in ears, dentures, face prosthesis,
breath tubes and joints. Engineering polymers, such as
PEEK, POM, polyamides and PTFE are used widely in medical
product manufacturing, such as catheters, micro-catheters,
nasogastric feeding tubes and endotracheal tubes.
One
important property which create technical challenges in a
production environment is the characteristic low surface
energy of polymers and the resulting intrinsically poor
adhesion characteristics. Various methods of improving
adhesion are available but often don’t lend themselves to
production settings and frequently involve the use of
harsh and environmentally unfriendly chemicals to
physically attack and etch the surface of the material.
Plasma surface modification offers a reliable and
environmentally friendly alternative surface preparation
for most engineering polymers.
 Plasma
treatment techniques have advantages over other approaches
because it has the ability to uniformly modify the surface
and a few top monolayers of the material surface without
any change in the bulk properties.
Plasmas can
be a vacuum types (batch) or atmospheric types (in-line)
and contain reactive gas species which, by careful choice
of gas type and process parameters, can be used to
increase the surface energy of a wide range of engineering
polymers, and in doing so significantly improve wetting
characteristics and therefore adhesion characteristics.
In-line
atmospheric plasma surface treatment has been successfully
demonstrated to increase the surface energy of PEEK from
35mN/m to >72mN/m, ensuring permanent PAD print adhesion.
The treatment is active on PEEK for several weeks and so
parts can be stored until needed. For PTFE catheters, air
is ineffective due to the strength of the C-F bond. Batch
processes are preferred which allow different plasma gases
to be used and which are more effective in fluorine
extraction from the surface. The surface energy of PTFE is
raised from 18mN/m to >72mN/m in this case also.
Both batch
and in-line plasma treatments offer a reliable and
repeatable surface preparation method for improving
adhesion to a wide range of engineering polymers used in
medical device manufacture.
(Ref:
http://www.medicalplasticsnews.com/technology/plasmatreatments-improve-adhesion-to-polymers/)
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