RILSAN® Polyamide 11 in Oil & Gas Off - HCL Fasteners Ltd

4
The excellent properties of polyamides
and in particular polyamide 11 are a result
of the amide linkages in the chain which
allow a strong interaction between the
chains by hydrogen bonds. Low creep,
high abrasion resistance, good resistance
to fatigue and high barrier properties are
a direct result of these strong inter-chain
links.
Molecules which can create hydrogen
bonds such as water, methanol, ethanol,
ethylene glycol can penetrate polyamide
11 and lead to plasticization. They can
interfere in inter-chain hydrogen bonds
thus weakening the hydrogen bond network.
Especially methanol has a significant
absorption rate and must be considered
in certain applications. Please refer
to section 3.6.
H–N
O=C
H–N
O=C
PA CHAINS WITH H-BONDING
C=O
N–H
N–H
IIIIIII
IIIIIII
H–N
O=C
C=O IIIIIII H-N
IIIIIII O=C
C=O IIIIIII H–N
N–H IIIIIII O=C
C=O IIIIIII H–N
N–H IIIIIII O=C
C=O
H–N
C=O
Although polyamide 11 is highly resistant
to aging and chain breakdown, the reaction
of water with amide bonds creates a
limit to the use of polyamide at higher
temperatures and in the presence of
water. The specific reaction induced by
water, called hydrolysis, can be accelerated
in the presence of acids. At continuous
service temperatures of 65°C and below,
the impact of hydrolysis on polyamide 11
in a neutral medium such as water can be
neglected. Under these conditions, the
material can have a service life of 20 years
or more. The use at higher continuous
service temperatures depends on the performance
requirements and more precise
conditions. The reader should refer to
data on temperature – lifetime correlations
in section 3.5.
O
=
REACTION: HYDROLYSIS
vvvvv C–Nvvvvv +H2O →
← vvvvv CO2H + vvvvv NH2
–
H
A special molecule, butyl-benzene-sulfonamide
or BBSA, has been chosen as a
plasticizer. It has very low volatility and
leads to an efficient plastification of the
resin. Questions related to its extraction
or its influence on material properties are
discussed in section 3.7.
BUTYL-BENZENE-SULFONAMIDE OR BBSA
O II
SII
O
N
H
A range of RILSAN ® polyamide 11 grades
has been developed to correspond to the
specific needs of the oil and gas industry.
BESNO P40 TL
A high viscosity and plasticized grade
developed for pipe extrusion.
BESNO P40 TLX
A high viscosity and plasticized grade
developed for pipe extrusion especially
for the inner pressure layer of flexible
pipe.
BESNO P40 TLO
A high viscosity and plasticized grade
developed for pipe extrusion with a low
extractable content especially adapted for
hydraulic hoses in umbilicals.
The blooming of oligomers has clogged
valves or filters in subsea installations.
Oligomeric molecules present in the
polymerized PA11 resin are extracted and
the material is compounded with a
plasticizer and heat additives.
BESNO P20 TL
A medium plasticized, high viscosity extrusion
grade for pipe and sheath extrusion.
BESNO TL
A high viscosity unplasticized grade
adapted for pipe extrusion.
BMNO TLD
An injection molding grade.
These grades are all of natural color.
Certain colored grades or color master
batches are also available.