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

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

Fig. 2 Morphology of a semicrystalline polymer

a. b.



● ●







● ● ●



● ● ●



d.

a. repeat unit cell b. crystalline (lc) and amorphous

(la) domains within the long period Lp (lamellar

structure) c. a stack of lamelle d. the spherolite.

1.1 Introduction to thermoplastic

polymers

Thermoplastic polymers are a class of

materials with a wide range of flexibility,

a medium range of elasticity and a wide

range of upper temperature limits. For

semicrystalline materials, their maximum

use temperatures are limited by the

melting point of the crystalline phase.

An image of the general structure of a

semicrystalline thermoplastic material is

given above. The properties of such a

material are governed by the interplay of

the crystalline phase giving strength and

temperature resistance and the amorphous

phase rendering the material

tough and flexible. Typical examples of

semicrystalline polymers are high density

polyethylene (HDPE), polyamide 11 or

nylon 11 (PA11) and polyvinylidene

fluoride (PVDF).

c.

lc

la

L p

The following table gives an outline of the scope of properties of thermoplastic

polymers which can be found in offshore applications today.

COMPARISON OF DIFFERENT THERMOPLASTIC POLYMERS USED IN OFFSHORE SERVICE

PVC HDPE PA11 PVDF

Density (g cm-3) 1.38 – 1.40 0.95 – 0.98 1.03 1.78

Melting Point (°C) 80 130 – 135 188 160 – 170

Flexural modulus (MPa) 1100 – 2700 700 – 1000 300 – 1300 800 – 2000

Tensile strength (MPa) 50 – 75 20 – 30 25 – 30 37 – 48

Shore D hardness 55 – 70 32 – 61 75 – 77

LOI (%) 42 5.7 26 44

1.2 General guide for the use of polyamide 11

Polyamide 11 is a specialty nylon. It combines high ductility, excellent aging resistance

and high barrier properties with mechanical strength and resistance to creep and fatigue.

It thus compares advantageously to standard nylons such as 6 and 66. Notably its significantly

lower water absorption results in better aging resistance, higher chemical resistance

and less property fluctuation due to plasticization by water.

COMPARISON OF DIFFERENT POLYAMIDES

PA 66 PA 6 PA 11 PA 11

plasticized

Melting point (°C) 255 215 188 184

Density 1.14 1.13 1.03 1.05

Flexural modulus (MPa)

50% RH (23°C) 2800 (1200) 2200 1300 300

Water absorption

50% RH (23°C) 2.5 2.7 1.1 1.2

in water immersion 8.5 9.5 1.9 1.9

Charpy notched impact

ISO 180/1A (kJ/m 2 )

23°C 5.3 (24) 8 (30) 23 N.B.

- 40°C X X 13 7

ISO 527

Tensile stress (MPa) 87 (77) 85 (70) 36 21

Tensile elongation (%) 5 (25) 22 –

Elongation at rupture (%) 60 (300) 15 – 200 360 380

N.B. = no break, values in parentheses at elevated humidities, RH = relative humidity

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