Standard Test Method for Determination of Linear Low Density Polyethylene (LLDPE) Composition by Carbon-13 Nuclear Magnetic Resonance

SIGNIFICANCE AND USE
Performance properties are dependent on the number and type of short chain branches. This test method permits measurement of these branches for ethylene copolymers with propylene, butene-1, hexene-1, octene-1, and 4-methylpentene-1.
SCOPE
1.1 This test method determines the molar composition of copolymers prepared from ethylene (ethene) and a second alkene-1 monomer. This second monomer can include propene, butene-1, hexene-1, octene-1, and 4-methylpentene-1.
1.2 Calculations of this test method are valid for products containing units EEXEE, EXEXE, EXXE, EXXXE, and of course EEE where E equals ethene and X equals alkene-1. Copolymers containing a considerable number of alkene-1 blocks (such as, longer blocks than XXX) are outside the scope of this test method.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See Section 8 for a specific hazard statement.
Note 1—There is no equivalent ISO standard.

General Information

Status
Historical
Publication Date
09-Jun-2003
Technical Committee
Drafting Committee
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ASTM D5017-96(2003)e1 - Standard Test Method for Determination of Linear Low Density Polyethylene (LLDPE) Composition by Carbon-13 Nuclear Magnetic Resonance
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e1
Designation:D5017–96 (Reapproved 2003)
Standard Test Method for
Determination of Linear Low Density Polyethylene (LLDPE)
Composition by Carbon-13 Nuclear Magnetic Resonance
This standard is issued under the fixed designation D5017; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Editorially changed content in Sections 2 and 3 in June 2003.
1. Scope 3. Terminology
1.1 This test method determines the molar composition of 3.1 Some units, symbols, and abbreviations used in this test
copolymers prepared from ethylene (ethene) and a second method are summarized in IEEE/ASTM SI-10 and Practice
alkene-1monomer.Thissecondmonomercanincludepropene, E386. Other abbreviations are listed as follows:
butene-1, hexene-1, octene-1, and 4-methylpentene-1. 3.2 Abbreviations:Abbreviations:
1.2 Calculations of this test method are valid for products 3.2.1 C—carbon 13,
containing units EEXEE, EXEXE, EXXE, EXXXE, and of 3.2.2 LLDPE—linear low-density polyethylene,
course EEE where E equals ethene and X equals alkene-1. 3.2.3 T1—relaxation time, and
Copolymers containing a considerable number of alkene-1 3.2.4 TR—pulse repetition time.
blocks(suchas,longerblocksthanXXX)areoutsidethescope 3.3 Definitions of Terms Specific to This Standard:
of this test method. 3.3.1 With a few modifications, terms used to designate
1.3 This standard does not purport to address all of the different carbon types were suggested by Carman. Methine
safety concerns, if any, associated with its use. It is the carbons are identified by CH and branch carbons are labeled
responsibility of the user of this standard to establish appro- according to branch type as summarized in Table 1. Branch
priate safety and health practices and determine the applica- carbons are numbered starting with the methyl as number one.
bility of regulatory limitations prior to use. See Section 8 for a 3.3.2 Backbone methylene carbons are designated by a pair
specific hazard statement. ofGreeklettersthatspecifythelocationofthenearestmethine
carbon in each direction. For example, a,a-methylene carbon
NOTE 1—There is no equivalent ISO standard.
+
is between two methine carbons or an a,d methylene carbon
has one immediate methine neighbor and the second methine
2. Referenced Documents
2 carbon is located at least four carbons away.
2.1 ASTM Standards:
E177 Practice for Use of the Terms Precision and Bias in
4. Summary of Test Method
ASTM Test Methods
4.1 Polymer samples are dispersed in hot solvent and
E386 Practice for Data Presentation Relating to High-
analyzed at high temperatures using Carbon-13 nuclear mag-
ResolutionNuclearMagneticResonance(NMR)Spectros-
netic resonance (NMR) spectroscopy.
copy
4.2 Spectra are recorded under conditions such that the
E691 Practice for Conducting an Interlaboratory Study to
response of each chemically different carbon is identical.
Determine the Precision of a Test Method
Integrated responses for carbons originated from the different
IEEE/ASTM SI-10 Standard for Use of the International
comonomers are used for calculation of the copolymer com-
System of Units (SI): The Modern System
position.
5. Significance and Use
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
5.1 Performance properties are dependent on the number
Current edition approved June 10, 2003. Published August 2003. Originally
and type of short chain branches. This test method permits
approved in 1991. Last previous edition approved in 1996 as D5017–96.
This revision includes the addition of an ISO equivalency statement and an
update of model numbers of referenced NMR instruments.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
Available from ASTM International Headquarters, 100 Barr Harbor Drive, Carman,C.J.,Harrington,R.A.,andWilkes,C.E., Macromolecules1977,Vol
C700, West Conshohocken, PA 19428. 10, p. 536.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
e1
D5017–96 (2003)
TABLE 1 Designations for Different Carbon Types NOTE 6—Thenuclearoverhauserenhancementforthecarbonsusedfor
4, 6 , 7
quantitative analysis have been shown to be full.
Monomer Branch Type Label
Propane (P) methyl M1
10. Procedure
Butene-1 (B) ethyl E1–E2
Hexene-1 (H) butyl B1–B4
10.1 Weigh a 1.2-g sample into a 10-mm NMR tube. Add
4-Methylpentene-1 (MP) isobutyl IB1–IB3
1.5 mLof solvent (7.1) and 1.3 mLdeuterated solvent (7.2) to
Octene-1 (O) hexyl H1–H6
the tube. Cap the tube.
NOTE 7—Solution concentration can be varied with instruments of
different field strength as long as one meets the minimum signal-to-noise
measurement of these branches for ethylene copolymers with
requirement of 9.4.
propylene, butene-1, hexene-1, octene-1, and
10.2 Homogenize the sample in an oven at 150°C for 3 to 4
4-methylpentene-1.
h. Keep the tube in a vertical position during the heating step.
10.3 Set spectrometer parameters as detailed in Section 9.
6. Apparatus
10.4 Transfer the tube to the NMR spectrometer and equili-
6.1 NMR Spectrometer, C pulse-Fourier transform with
brate 10 to 15 min at 130°C.
fieldstrengthofatleast2.35T.Typicalinstrumentsincludethe
10.5 Scan the sample with complete broadband decoupling
JeolGSX-400,BrukerAvanceDPX-300,andVarian400Unity
using the parameters of Section 9.
PLUS spectrometers.
10.6 Record the spectrum and the accurate full-scale inte-
NOTE 2—The system should have a computer size of at least 32 K for
gralfrom10to50ppm.Adjustpartialintegralssothatintegral
50-MHz carbon frequency with digital resolution of at least 0.5 Hz/point
of the second largest peak in the spectrum is at least 50% of
in the final spectrum.
full-scale.This partial integral must be flat before and after the
6.2 Sample Tubes, 10-mm outside diameter.
area to be measured.
NOTE 3—Sample tube size can be varied; however, the sample prepa-
NOTE 8—The combination of sample preparation time and acquisition
ration procedure described in 10.1 may need to be altered to maintain the
timenecessarytoobtainthesignal-to-noiserequirementof9.4canleadto
minimum signal-to-noise requirement of 9.4.
prohibitively long experiments if samples are run multiplicatively. It is
acceptable to perform sample determinations using a single analysis.
7. Reagents and Materials
Duplicate runs in accordance with 13.1 were performed for the round-
robin exercise.
7.1 Ortho-dichlorobenzene or 1,2,4-trichlorobenzene, re-
agent grade
11. Calculation
7.2 Deuterated o-dichlorobenzene or p-dichlorobenzene.
11.1 Measure the area between the appropriate integration
This material is used at a concentration up to 20% with the
limits outlines in Annex A1.
reagent specified in 7.1 as an internal lock.
11.2 Substitute the integrals into the appropriate equations
8. Hazards from Annex A2 to calculate the mole percent alkene-1.
11.3 Annex A3 gives a sample calculation for an ethylene-
8.1 Precaution: Solvents should be handled in a wellven-
octene copolymer using integrals and equations in accordance
tilated fume hood.
with 11.1 and 11.2.
9. Instrument Parameters
NOTE 9—With the prescribed repetition time (10 s) and pulse angle
9.1 Pulse angle, 90° (90°), the maximum allowable relaxation time (T ) for carbons used for
quantitative analysis is 2 s. To shorten the analysis time, a shorter pulse
9.2 Pulse repetition, 10 s
repetition time can be used if one accounts for the relaxation time
9.3 Sample temperature, 130°C
differences. Relaxation times of carbons for the five copolymers were
determinedatacarbonfrequencyof50MHzusingtheinversionrecovery
NOTE 4—The precise temperature should be measured using the NMR
6 8, 9
method. Annex A4 summarizes these relaxation times and correction
thermometer (cyclooctane/methylene iodide).
factors(reciprocaloftherelativeintensities)fora4-srepetitiontime(T ).
R
9.4 Minimum signal-to-noise, 5000:1
With the shorter T , multiply integrals by these correction factors before
R
using the equations in Annex A2. The T values would have to be
NOTE 5—The signal-to-noise ratio is defined as 2.5 times the signal 1
remeasuredforanalysesperformedatspectrometerfrequenciesotherthan
intensity of the 30.0-ppm peak (isolated methylenes) divided by the peak
50 MHz.
to peak noise for the region from 50 to 70 ppm. Calculation of
signal-to-noise is permitted using an equivalent software procedure.
11.4 If desired, convert results from mole percent alkene-1
9.5 Sweep width, 175 ppm tobranchesper1000carbons(br/1000C)usingtheequationsin
9.6 Transmitter frequency (F1), 50 to 55 ppm Annex A5.
9.7 Apodisation, 2 (exponential) Hz
−1
9.8 Pulse width, <[4 3sweep width Hz]
9.9 Decoupling, complete
Randall, J. C., “NMR and Macromolecules,” Chapter 9, American Chemical
Society Symposium Series 247, 1984.
Farrar,T.C.,andBecker,E.D., Pulse and Fourier Transform NMR,Chapter2,
Available from Wilmad Scientific Glass Co. Academic Press, New York, 1971.
6 9
Vidrime, D. W., and Peterson, P. E., Analytical Chemistry, Vol 48, 1976, p. Cheng, H. N., and Bennet, M. A., Macromolecule Chemistry, Vol 188, 1987,
1301. pp. 2665–2677.
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D5017–96 (2003)
12. Report prepared at the laboratories that tested them. Each “test result”
was the average of two individual determinations. Each labo-
12.1 Report the mole percent alkene from 11.2 or branches/
ratory obtained one test result for each material.
1000C from 11.4, or both.
NOTE 10—Caution:The following explanations of r and R (13.2-
13. Precision and Bias
13.2.3) are only intended to present a meaningful way of considering the
approximate precision of this test method. The data in Table 2 should not
13.1 Table 2 is based on a round robin conducted in 1988
be rigorously applied to acceptance or rejection of material, as those data
in accordance with Practice E691, involving nine materials
arespecifictotheroundrobinandmaynotberepresentativeofotherlots,
tested by six laboratories. For each material, all the samples
conditions, materials, or laboratories. Users of this test method should
werepreparedatonesource,buttheindividualspecimenswere
apply the principles outlined in Practice E691 to generate data specific to
their laboratory and materials, or between specific laboratories. The
principles of 13.2-13.2.3 would then be valid for
...

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