1、Designation: D 5492 06Standard Test Method forDetermination of Xylene Solubles in Propylene Plastics1This standard is issued under the fixed designation D 5492; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method is to be used for determining the 25Cxylene-soluble fraction of polypropylene homopolymers andcopolymers.1.2
3、This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1This test met
4、hod is technically equivalent to ISO 16152.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1600 Terminology for Abbreviated Terms Relating toPlasticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:IS
5、O 16152 PlasticsDetermination of Xylene Solubles ofPolypropylene33. Terminology3.1 Definitions:3.1.1 For definitions of plastic terms see Terminology D 883and for abbreviations see Terminology D 1600.3.2 Definitions of Terms Specific to This Standard:3.2.1 soluble-fraction (SS)the percentage of the
6、polymermass that does not precipitate out when the polymer solution iscooled from reflux temperature to +25 6 0.5C and held at thattemperature for a specified period of time.4. Summary of Test Method4.1 A weighed amount of sample is dissolved in xyleneunder reflux conditions. The solution is cooled
7、under con-trolled conditions and maintained at a +25C equilibriumtemperature so that the crystallization of the insoluble fractiontakes place. When the solution is cooled the insoluble portionprecipitates and is isolated by filtration. The ortho-xylene isevaporated from the filtrate, leaving the sol
8、uble fraction in theresidue. The percentage of this fraction in the plastic isdetermined gravimetrically.5. Significance and Use5.1 The results of this test provide a relative measure of thetotal soluble fraction of polypropylene homopolymers andcopolymers. The soluble fraction can be approximately
9、corre-lated to the amorphous fraction in the polypropylene. Xylene iswidely used for determining the soluble fraction in polypropy-lene. Xylene is more specific to the atactic fraction than othersolvents. The concentration of a soluble fraction obtained witha specific solvent has been found to relat
10、e closely to theperformance characteristics of a product in certain applica-tions, for example film and fiber. Data obtained by one solventand at one precipitation time cannot be compared with dataobtained by another solvent or precipitation time, respectively.6. Interferences6.1 Materials with solu
11、bilities similar to the soluble frac-tion, such as additives, may interfere with the measurement ofsolubles. When present in concentrations that are judged toimpart a significant error to the soluble-fraction data, the levelof interference must be determined and corrections made.6.2 Small-particle f
12、illers and pigments that may passthrough the filter and insoluble gels present in the polymer maycause errors in the measurement.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-als.Current ed
13、ition approved May 1, 2006. Published June 2006. Originallyapproved in 1994. Last previous edition approved in 2003 as D 5492 - 98(2003).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume i
14、nformation, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Driv
15、e, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 The polymer flakes and spheres must be dried beforetesting to eliminate moisture that can influence the initialweight of sample added to the flask.7. Apparatus7.1 Reflux-Condenser Apparatus, 400 mm, with 24/40 glassjoint.7.2 Flat-Bo
16、ttom Boiling Flask, with one or two necks, 400mL with 24/40 joint, Erlenmeyer flask, or cylindrical bottle.7.3 Insulation Disk, made of fiberglass or rock wool.7.4 Electromagnetic Stirrer Unit, with temperature-controlled heating plate, thermostatted oil bath, or heater blockcapable of maintaining 1
17、45 to 150C.7.5 Stirring Bar.7.6 Pipet, Class A, 200 mL or equivalent.7.7 Pipet, Class A, 100 mL or equivalent.7.8 Glass-Stoppered Volumetric Flask, 250 mL.7.9 Thermostatically Controlled Water Bath, at +25 60.5C.7.10 Electromagnetic Stirrers.7.11 Filter Paper, fluted, Whatman No. 4, No. 541,4orequiv
18、alent, at least 125 mm in diameter.7.12 Funnel, 60, or equivalent, at least 125 mm in diam-eter.7.13 Heated Vacuum Oven.7.14 Aluminum Pans, 300-mL capacity, with smooth sidesor other suitable container of similar design.7.15 Temperature-Controlled Heating Plate.7.16 Analytical Balance, with minimum
19、weighing sensitiv-ity to 0.0001 g (a sensitivity of 0.00001 g is preferred).7.17 Desiccator, containing appropriate desiccant.7.18 Timer, preferably with an alarm, in minutes.7.19 Oven, conventional forced air or gravity.8. Reagents8.1 Reagent-Grade Ortho-Xylene (o-Xylene)Assay gaschromatography (GC
20、) = 98 % min; less than 2 % ethylbenzeneas established by GC; evaporation residue at 140C less than0.002 g/100 mL; boiling point 144C.8.2 Reagent-Grade Para-Xylene (p-Xylene)Assay gaschromatography (GC) = 98 % min; less than 2 % ethyl-benzene as established by GC, evaporation residue at 140Cless tha
21、n 0.002 g/100 mL; boiling point 138C.NOTE 2Mixed xylene may be used within a laboratory if the ratio ofpara-xylene to ortho-xylene remains constant from lot to lot and the levelof ethyl-benzene is less than 2 %.NOTE 3Grade ortho-xylene shall be used as the reference solventwhenever there is a disput
22、e between laboratories on test results, unless thelaboratories agree otherwise.9. Procedure9.1 Preparation of the Xylene:9.1.1 Stabilization of the xylene is not required. Whentesting non-stabilized polypropylene powders or spheres, anti-oxidants may be added to prevent degradation. This addition is
23、optional if previous testing shows there is no significant changein xylene soluble level.NOTE 4Butylated hydroxyl toluene (BHT), 4,4 thiobis (6-tert-butyl-m-cresol), and tetrakis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamate)methane at an approximate concentration of 0.02 g/L of xylene have beenfound
24、to be effective stabilizers. Agitate with a magnetic stirring bar andheat for a minimum of one hour at 80C to 90C to ensure the thoroughmixing of the antioxidants and the xylene. This is a suitable heatingtemperature for BHT, which is highly volatile.9.1.2 Degas the xylene. Using nitrogen gas, purge
25、 thexylene for a minimum of 1 h every 24 h.9.2 Determine the Level of Contamination in the Xylene(Solvent Blank):9.2.1 The purpose of the solvent blank is to determinewhether the xylene to be used contains significant amounts ofevaporation residue or foreign components. A solvent-blanktest for resid
26、ue should be run on every new lot of xylene. Testand average the solvent-blank results, for three aliquots perbottle or lot of xylene. Each aliquot shall be 200 mL.NOTE 5If the xylene is an extrapure grade (minimum 99.5 %) and isused immediately after being opened, the determination of the blank may
27、be eliminated. If not used immediately (within three days) a solvent blankmust be run. It is recommended that xylene be purchased in glass orglass-lined containers and of a size such that the xylene will be usedwithin three days, once opened. Containers of larger size may be used ifthe xylene is use
28、d up within a short period of time. The purpose of theshort time period is to ensure purity and minimize moisture pickup andother contaminants.9.2.2 Pipet 200 mL of unstabilized or stabilized xylene intoa clean empty flask.9.2.3 Place a 125-mm diameter or larger No. 4 filter paperor equivalent in a
29、125-mm diameter of larger funnel in a funnelrack over a 250-mL glass-stoppered flask.9.2.4 For each sample blank, pour the contents from theflask into a funnel and allow the filtrate to drip into a secondflask. Continue the filtration until all the filtrate has beencollected.9.2.5 Dry the aluminum p
30、ans (or other suitable container)for 30 min in an oven at 200C. Cool the pans in a desiccatoruntil ready to use. For each sample weigh a clean, dry pan onthe analytical balance to the nearest 0.0001 g.9.2.6 With a Class A pipet, pipet a 100-mL aliquot of thefiltered xylene into the weighed pan.9.2.7
31、 Place the pan on a temperature-controlled heatingplate maintained at 145 to 150C. Allow the aliquot to obtaina rolling boil to prevent splashing. Blanket the pan with a slowstream of nitrogen. Continue heating the pan until the residuein the dish is almost dry.9.2.8 Place the pan into a vacuum oven
32、 at 100 6 10C at apressure less than 13.3 kPa for a known suitable time whereconstant weight is observed.9.2.9 Cool the pan to room temperature in a desiccator for aminimum of 15 minutes and weigh the pan to the nearest0.0001 g. Calculate the average blank-residual mass of thethree determinations.9.
33、3 Determine the Percent Soluble Fraction in the Polymer:4The sole sources of supply (EU/U.S.) of the apparatus known to the committeeat this time are Whatman Intl. Ltd., Maidstone, England or from Fisher Scientific,711 Forbes Ave., Pittsburgh, PA 15219. If you are aware of alternative suppliers,plea
34、se provide this information to ASTM International Headquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.D 5492 0629.3.1 Dry the polypropylene powder or spheres beforeanalysis. It is not necessary to dry the pellets un
35、less it is knownthat they contain high levels of moisture. If necessary, dry thesamples in a vacuum oven at 70 6 5C, in a vacuum of 13.3kPa for a minimum of 20 min. Cool the sample in a desiccatorto prevent moisture pickup.NOTE 6For large pellets or spheres, where there is concern that thepolymer sa
36、mple will not dissolve in a reasonable time frame, the pellets orspheres may be ground to an appropriate size to afford a faster dissolution.Attention shall be paid not to mechanically shear the polymer and increasethe residual solubles level. Ground material shall be dried as specified in9.3.1.9.3.
37、2 Weigh out a sample in accordance with Table 1. Whenthe expected solubles level is unknown or referee testingbetween laboratories is being conducted, a 2.0 6 0.1 g sampleshall be used, unless there is agreement between the laborato-ries to use a different sample size. Determine mass of thesample to
38、 the nearest 0.0001 g. Pour the sample into aflat-bottom boiling flask. Place a magnetic stirring bar in theflask.NOTE 7Table 1 provides a choice of sample mass. Use the largestsample mass possible to minimize variability of the test data, unless fromprior experience it is known that the polymer/xyl
39、ene solution does notfilter readily as in 9.3.13.9.3.3 Pipet 200 mL of unstabilized or stabilized xylene intothe flask.9.3.4 Attach the flask to the condenser.9.3.5 Place an insulation disk on top of the electromagneticstirrer plate to prevent localized heating of the flask. Positionthe flask and co
40、ndenser system on top of the insulation disk(see Fig. 1). Position the nitrogen inlet tube in the top of thecondenser. Turn on the cooling water to the condenser.9.3.6 Blanket the contents of the boiling flask with a slowflow of nitrogen directed across the top of the condenser, notdirectly into the
41、 condenser, to minimize possible xylene loss.Nitrogen flow rate shall be approximately 2 L/h.9.3.7 Heat the polymer/xylene mixture to reflux temperaturewhile vigorously stirring. The stirring shall be vigorous enoughto obtain a deep vortex, which keeps the boiling under controland prevents boiling u
42、p into the condenser. Ensure that thereflux is gentle so that localized burning and sticking of thepolymer to the flask walls does not occur.9.3.8 Once the reflux temperature is reached, stir the solu-tion for an additional 30 min. The liquid will appear water-clear.9.3.9 Remove the heating plate fr
43、om beneath the flask.Detach the flask from the condenser and lightly stopper theflask. Cool the solution temperature from reflux temperature tobelow 100C by cooling the flask in air for 12 to 14 min. Atimer, preferably with an alarm, must be used to ensure that thesolution is cooled to within a narr
44、ow range of temperature fromrun to run.9.3.10 Transfer the flask to a thermostatically controlledwater bath at 25 6 0.5C. Do not shake the flask to break upany precipitate before immersing the flask in the bath.NOTE 8Do not shake the flask while the xylene-polymer solution isstill hot as this may cr
45、eate a safety hazard.NOTE 9Because the rate of cooling affects the crystal size and the rateof crystallization, the time and temperature during the cooling steps arevery critical to the final test result.NOTE 10The water bath must have sufficient cooling capacity tomaintain a constant temperature of
46、 25 6 0.5C during cooling.9.3.11 Precipitation Time9.3.11.1 Without stirring, cool the solution for 30 min in thetemperature-controlled bath at 25 6 0.5C. Using a timer,preferably with an alarm, to ensure that the solution-precipitation time ranges from 30 to 32 min. Remove the flaskfrom the tempera
47、ture-controlled bath. Stir or gently shake theflask to break up any precipitated-polymer gel.NOTE 11Shorter precipitation times (for example, comparing 30minutes versus 60 minutes or longer) lead to higher values of solublecontent for propylene plastics. Users of this method should be warned thatpro
48、duct specification ranges may need to be adjusted in order tocompensate for these differences.NOTE 12With the shorter 30 minute precipitation time, a true equi-librium will not be reached. Consequently, it is very critical that both theprecipitation time and cooling temperature be controlled very pr
49、ecisely tominimize variance.9.3.12 Place a 125-mm diameter or larger No. 4 filter paperor equivalent in a 125-mm diameter of larger funnel in a funnelrack over a 250-mL glass-stoppered flask.TABLE 1 Sample SizeExpected Solubles Initial Sample Mass, gA30.0 % by mass 2.0000 6 0.1000 or 1.0000 6 0.1000ASee Note 7.FIG. 1 Equipment SetupD 5492 0639.3.13 For each sample, pour the contents from the flaskinto a funnel and allow the filtrate to drip into the second flask.NOTE 13With some materials that may have been compounded withfiller or rubber, it may
