DURABILITY OF POLYPROPYLENE TUBES « DRAINTUBE ».
9Pages

Durability of Polypropylene Tubes “DRAINTUBE” Presented to : Richard Faucher Texel Inc. Prepared by : David Beaumier Project Leader Éric Blond Vice president

S006-159 Durability of polypropylene tubes “DRAINTUBE” Page 2 DURABILITY OF POLYPROPYLENE TUBES “DRAINTUBES” File: S006-159 Submitted to: TEXEL INC. 485 des Érables, Saint Elzéar de Beauce Québec G0S 2J0 Prepared by: David Beaumier, eng., M.Sc.A. Project Leader, SAGEOS Eric Blond, eng., M.Sc.A. Vice president, SAGEOS June 2, 2008

S006-159 Durability of polypropylene tubes “DRAINTUBE” Page 4 / 9 1 INTRODUCTION 1.1 Objective - Determine the durability of draintubes, and compare with a product of reference. 1.2 Theoretical approach 1.2.1 Materials degradation The degradation mechanism of polyolefin, as shown in figure 1, usually undergoes four stages: antioxidant depletion, induction period, acceleration period, and deceleration period. Oxygen Absorption Antioxidants Depletion Time Durability Property change (%) 100% 50% Induction Period Acceleration Period Deceleration Period Aging Time Aging Time A : Antioxidants...

S006-159 Durability of polypropylene tubes “DRAINTUBE” Page 5 / 9 residual life of a polyolefin product (such as polyethylene) until the antioxidants are completely depleted. The induction period is the lag time before the chain scission of the polymer backbone will occur. During this period, it can be observed that the mechanical properties of the material do not vary significantly but the OIT has reached a value close to ‘zero’. Once the oxidation process has started, the polymer properties will change because of molecular chain scission. In addition, the melt index (ASTM D1238) will...

S006-159 Durability of polypropylene tubes “DRAINTUBE” Page 6 / 9 From equation 2, the observed trend was projected and the degradation rate could be calculated at any temperature. By inserting it in equation 1, the OIT value was projected for a given temperature. Time Ln(OIT) 40° 55° 70° 85° Slope 1 / Temperature Slope (85°C (70°C (55°C (40°C Figure 2: Key principle of the Arrhenius model 2 MATERIALS The materials selected for this evaluation were as follows: - A draintube, made from polypropylene resin and claimed to be representative of a typical production run by the manufacturer; - A...

S006-159 Durability of polypropylene tubes “DRAINTUBE” Page 7 / 9 Figure 3: OIT prediction model of draintube D20 Arrhenius Projection Polypropylene Tube 'Draintube' y = -6184,5x + 9,0633 R2 = 0,934 -11,0 -10,5 -10,0 -9,5 -9,0 -8,5 -8,0 0,0028 0,0028 0,0029 0,0029 0,0030 0,0030 0,0031 0,0031 0,0032 0,0032 0,0033 1/T ln(k) Reaction of first order Figure 4: Arrhenius projection for Draintube

S006-159 Durability of polypropylene tubes “DRAINTUBE” Page 8 / 9 Figure 5: OIT prediction model of a HDPE geonet Arrhenius Projection Polyethylene Geonet y = -2848,6x + 0,3342 R2 = 0,8489 -9,0 -8,5 -8,0 -7,5 -7,0 0,0028 0,0028 0,0029 0,0029 0,0030 0,0030 0,0031 0,0031 0,0032 0,0032 0,0033 1/T ln(k) Reaction of first order Figure 6: Arrhenius projection for HDPE Geonet

S006-159 Durability of polypropylene tubes “DRAINTUBE” Page 9 / 9 Basing on these observations, the parameters of the Arrhenius equation for OIT prediction were deducted and ploted as shown on Figures 4 and 6. The antioxidant depletion time could then be estimated considering a service temperature of 20°C. This prediction model has shown that the draintube will be adequately protected against oxidation during an indicative duration of at least 80 years, while this duration could be approximately 40 to 100 years for the tested HDPE geonet. Given that actual field conditions may tremendously...