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APPENDIX G
Proposed Draft Standard Specification
for Recycled Content Containing HDPE Resin
Formulations for Corrugated Pipe Made to
AASHTO Standard M294-Recycled
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DRAFT
____________________________________________________________
Standard Specification for
SPECIFICATION FOR RECYCLED CONTAINING HDPE
RESIN FORMULATIONS FOR CORRUGATED PIPE MADE TO
AASHTO SPECIFICATION M-294-RECYCLED
AASHTO Draft Standard XXX-XX
____________________________________________________________
1. SCOPE
1.1 This specification covers the quality HDPE resin formulations containing
recycled HDPE that are intended for use in AASHTO M294Recycled approved
corrugated drainage pipe, in sizes 300- to 1500-mm (12- to 60-in) diameter.
1.2 The recycled polyethylene may be either post-commercial or post-industrial.
1.3 This specification presents a set of properties to be met for the resin and test
frequencies.
1.4 This specification can be used by resin containing recycled PE suppliers as part
of manufacturing quality control (MQC), or by pipe manufacturers or
independent bodies as manufacturing quality assurance (MQA).
______________________________________________________________________
2. REFERENCED DOCUMENTS
2.1 ASTM Standards:
D638, Test Method for Tensile Properties of Plastics
D790, Test Method for Flexural Properties of Unreinforced and Reinforced
Plastics and Electrical Insulating Materials
D792, Test Methods for Density and Specific Gravity (Relative Density) of
Plastics by Displacement
D1238, Test Method for Melt Flow Rates of Thermoplastics by Extrusion
Plastometer
D1505, Test Method for Density of Plastics by the Density-Gradient
Technique
D3895, Standard Test Method for Oxidative-Induction Time of Polyolefins
by Differential Scanning Calorimetry
D4218, Test Method for Determination of Carbon Black Content in
Polyethylene Compounds By the Muffle-Furnace Technique
D4703, Practice for Compression Molding Thermoplastic Materials into Test
Specimens, Plaques, or Sheets
D5630, Test Method for Ash Content in Plastics
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F2136, Standard Test Method for Notched, Constant Ligament-Stress
(NCLS) Test to Determine Slow-Crack-Growth Resistance of HDPE Resins
or HDPE Corrugated Pipe
______________________________________________________________________
3. TERMINOLOGY
3.1 Mixed-Color PCR-HDPE Post-Consumer Recycled HDPE that is composed
of mostly colored detergent bottles.
3.2 Natural PCR-HDPE Post-Consumer Recycled HDPE that is composed of milk
bottles.
3.3 Post-Consumer Recycled HDPE (PCR-HDPE) Polyethylene that has been
discarded by consumers after use, then collected, cleaned and washed. The
density is greater than 0.940 g/cm3 and typical sources include primarily bottles
and some bags.
3.4 PCR-HDPE Regrind Post-Consumer Recycled HDPE that has been cleaned,
washed, and ground into plastic chips.
3.5 Post-Industrial Recycled HDPE (PIR-HDPE) Polyethylene that has been
obtained for recycling from industrial sources. This may include industrial scrap,
rejected parts, or surplus goods.
3.6 Reprocessed PCR-HDPE Post-Consumer Recycled HDPE that has been
cleaned, washed, melt-filtered, and pelletized. Commonly known as "Repro."
______________________________________________________________________
4. REQUIRED PROPERTIES
4.1 The required properties for corrugated pipe resins containing recycled HDPE
are given in Table 1. Specific details of the tests are found in Section 7.
4.2 In addition to the properties in Table 1, the percentage recycled shall be
disclosed by the resin supplier and included on the resin certification.
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Table 1. Required properties for corrugated pipe resins containing recycled HDPE.
Property Test Method Sample Specified Frequency
Value
Density ASTM D1505 Pellets/Plaque >0.947- 0.955 a 1 per shift
ASTM D792 g/cm
Melt Index ASTM D1238 Pellets/Plaque <0.4 g/10 min 1 per shift
190°C/2.16 Kg
% Volatiles 175°C/1 Hour Pelletsb <0.2 % Certifyc
% Carbon ASTM D4218 Pellets/Plaque 2-4 % 1 per shift
Black
% Ash ASTM D5603 Pellets/Plaque <0.5 % 1 per shift
% PP DSC Plaque <5.0 % 1 per lotd
Section 7.6
Flexural ASTM D790 Plaque >130,000 psi 1 per lot
Modulus
Yield Stress ASTM D638e Plaque >3500 psi 1 per lot
Break Strain ASTM D638f Plaque >200 % 1 per lot
NCLS Stress- ASTM F2136 Plaque 36 hrs 1 per lot
Crack Test
OIT ASTM D3895 Pellets/Plaque 50 ming 1 per lot
BFF Stress- Section 7.9 Plaque 200 hrs 1 per lot
Crack Test 80°C/650 psi
a
Correct for carbon black by Dcor = D 0.0044C, where C is % carbon black.
b
Tested on pellet samples before melt blending.
c
Manufacturer will provide a certificate stating their material will lose less than 0.2% of its weight when a
2.000- ± 0.100-g sample is heated at 350°F for 1 h.
d
A production lot is defined as either a truckload, or one compartment of a railcar. Its weight is generally
between 40,000 and 50,000 lbs.
e
Strain rate shall be 2.0 in. per minute.
f
Assume 2.0in. gage length.
g
A common additive package that meets this requirement is 1,000 ppm Irganox 1010 plus 1,000 ppm
Irgaphos 168, or equivalent.
______________________________________________________________________
5. SAMPLING
5.1 A production lot shall be considered as a truckload or shipping container full of
1,500 lb boxes of resin, or one compartment of a railcar. The weight is
normally between 40,000 and 50,000 lb.
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5.2 A truckload shall be sampled by obtaining 0.5 lb of material from each of eight
boxes, for a total of 4 lb of resin. This is about every fourth box. Combine the
eight samples to form a lot sample.
5.3 A compartment of a railcar shall be sampled by obtaining 2 lb from the top and
2 lb from the bottom of the compartment. Combine the two samples to form a
lot sample. Therefore, each railcar will have four lot samples for evaluation.
5.4 The entire lot sample shall be dry blended before sample preparation. A
convenient way to do this is by hand in a 5-gallon plastic pail.
5.5 Divide the lot sample into two; one for immediate testing and the other for
validation testing, should the need arise. The back-up sample will be kept for 90
days after the resin is sold.
5.6 Clearly label the sample and include a traceable production number and a date.
______________________________________________________________________
6. SAMPLE PREPARATION
6.1 Homogenize about 2 lb (900 g) of material by melt blending, preferably with a
twin screw laboratory extruder. A two roll mill is also acceptable.
6.2 The blended material shall be compression molded into plaques according to
ASTM D4703, with the use of a 15°C/min. cooling rate.
6.3 The plaques shall be 1.9- 0.08-mm (0.075- 0.003-in.) thick for tensile and
NCLS testing, 3.2-mm (0.125-in.) thick for flexural modulus, and 1.1-mm
(0.043-in.) thick for the BFF test.
6.4 The plaques shall be allowed to equilibrate at standard laboratory conditions
(72°F, 50% RH) for at least 12 hours.
______________________________________________________________________
7. TEST METHODS
7.1 Test Conditions Unless otherwise specified in the test methods or in this
specification, conduct tests at the standard laboratory temperature of 23 2°C
(73.4 3.6 °F).
7.2 Density Test methods ASTM D1505 or D792 are acceptable. Make three
separate determinations using separate pellets or separate portions of a
plaque. The plaque thickness shall be 1.9 0.08 mm (0.075 .003 in.).
Calculate and report the average and standard deviation from the mean.
Correct the density value for % carbon black by subtracting 0.0044 g/cm3 for
each percent of carbon black.
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7.3 Melt Index Test method ASTM D1238, using Condition 190/2.16. Make
duplicate determinations on either pellets or a plaque and calculate the
average.
7.4 % Volatiles This test shall be performed in aluminum pans that have been
heated at 350°F (177°C) until they obtain a constant weight.
7.4.1 Test duplicate samples.
7.4.2 Weigh 2.000 ± 0.100 grams of pellets or a plaque to an accuracy of three
places past the decimal point into an aluminum pan.
7.4.3 Place the pan in a forced-air recirculating oven preheated and stabilized to 350
± 5°F (177 2°C) for a period of 1 h.
7.4.4 Remove the pan and let it completely cool to room temperature in a desiccator.
7.4.5 Reweigh the pan and calculate the percentage weight loss of the sample.
Report the average to the nearest 0.01%.
7.5 % Ash - Test method ASTM D5630, Procedure B.
7.5.1 Sample size shall be 1 g.
7.5.2 Heat at least 10 minutes at 800°C.
7.5.3 Test triplicate samples.
7.6 % Polypropylene
7.6.1 Generate a melting curve by differential scanning calorimetry (DSC) at a
heating rate of 10°C/min from room temperature to 200°C. See Figure 1.
0
-1
Heat Flow (W/g)
-2
-3
-4
20 40 60 80 100 120 140 160 180 200
Exo Up Temperature (°C) Universal V4.5A TA Instruments
Figure 1. DSC curve of HDPE containing PP generated.
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7.6.2 The curve shall be expanded to a range that includes the end of the HDPE
peak and the complete PP peak. See Figure 2.
-0.56
150.59°C
-0.58 2.568J/g
142.71°C
-0.60
Heat Flow (W/g)
-0.62
162.84°C
-0.64
-0.66
130 140 150 160 170 180
Exo Up Temperature (°C) Universal V4.5A TA Instruments
Figure 2. DSC curve of HDPE containing PP expanded.
7.6.3 Integrate the curve from a flat point before the PP melting to a point where the
PP curve returns to baseline.
7.6.4 Mark the point where the HDPE melt returns to baseline. The end of the HDPE
melt and the beginning of the PP melt will not necessarily be the same point.
7.6.5 Record the HDPE end-of-melt temperature and the PP heat of fusion in J/g.
7.6.6 Calculate the theoretical heat of fusion for 100% polypropylene for the portion
of the PP melting curve that does not overlap with HDPE by:
Y = -0.035X2 + 8.851X 475.6 (1)
Where: X = HDPE end-of-melt temperature (°C)
And Y = Hf of 100% PP not overlapped with HDPE.
For X = 142.7, Y = 74.7 J/g.
7.6.7 Calculate the percentage PP by:
%PP = Hf sample/ Hf 100% PP x 100 (2)
For Hf sample = 2.57 J/g, %PP = 3.4 %
7.6.8 Test two specimens from different parts of the molded plaque and report the
average.
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7.7 Flexural Modulus Test by ASTM Method D790. The test specimens shall be
2.5 in. x 0.5 in. (w) x 0.125 in. (t). A span of 2.0 in. will be used at a crosshead
rate of 0.5 in. per minute. Report the 2% secant modulus. Test five replicates
and report each result, along with the average and standard deviation.
7.8 Yield Stress/Break Strain Test by ASTM Method D638, with a Type IV
dumbbell at 2-in./min crosshead speed.
7.8.1 Test five specimens, individually measured for thickness.
7.8.2 2.0-in. gage length, use crosshead to follow displacement.
7.8.3 Report five results, average, and standard deviation.
7.9 NCLS Stress Crack Test Test 1.9-mm plaque for slow-crack growth with
ASTM F2136 with a notch depth of 20% of the test specimen thickness and
under an applied load of 4,100 kPa (600 psi).
7.9.1 Test five replicates and report the average and standard deviation.
7.10 Oxidative Induction Time (OIT) Test by ASTM D3895 at 200°C in oxygen in
duplicate and report the average time.
7.11 BFF Stress Crack Test This test is performed with the use of common stress
crack frames in deionized water at 80°C (176°F), under an applied stress of 650
psi.
7.11.1 A bath that has never contained Igepal or other surfactants is preferred.
Residual surfactant can dramatically accelerate the test.
7.11.2 The test specimen is basically an ASTM D638 Type I Dumbbell with a couple of
modifications. First, a 7/32in. hole is drilled into each head portion so that the
specimens can be mounted with a screw in a conventional stress crack testing
device. However, because of the holes, the tabs on each side of the hole are
narrower than the reduced section of the dumbbell. Therefore, the highest
stressed areas are the tabs, so all the specimens would naturally fail at the
tabs. To get around this, a 6in. square open faced mold was modified to
produce plaques that were about 45 mil in the center and over 90 mil on the
edges. This way, the tabs are under less stress than the reduced section so
nearly all of the failures occur in the reduced section. A drawing of the fathead
test specimen is shown in Figure 3.
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Figure 3. Fathead specimen used in the BFF test.
7.9.2 The test device is manufactured by BT Technology and is shown in Figure 4.
The weight tubes were modified to allow for the higher loads used in this test.
Figure 4. Load frame for the BFF test.
7.9.2 Five replicates are tested and the average and standard deviation reported.
___________________________________________________________________
8. RETEST AND REJECTION
8.1 If any failure occurs, the material shall be retested to establish conformity in
accordance to the specified property. A second failed result will result in
rejection of the lot for the purposes of this specification.
______________________________________________________________________
9. CERTIFICATION
9.1 Upon request of the purchaser in the contract or order, a manufacturer's
certification that the material was manufactured and tested in accordance with
this specification, together with a report of the test results, and the percentage
recycled shall be furnished at the time of shipment.
