1、Designation: D5492 10Standard Test Method forDetermination of Xylene Solubles in Propylene Plastics1This standard is issued under the fixed designation D5492; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 Thi
3、s 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 method
4、 is technically equivalent to ISO 16152.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology for Abbreviated Terms Relating toPlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 1615
5、2 PlasticsDetermination of Xylene Solubles ofPolypropylene33. Terminology3.1 Definitions:3.1.1 For definitions of plastic terms see Terminology D883and for abbreviations see Terminology D1600.3.2 Definitions of Terms Specific to This Standard:3.2.1 soluble-fraction (SS)the percentage of the polymerm
6、ass 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 under co
7、n-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 xylene is evapo-rated from the filtrate, leaving the soluble fractio
8、n 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 approximately correlates tothe am
9、orphous fraction in the polypropylene. Xylene is widelyused for determining the soluble fraction in polypropylene as itis more specific to the atactic fraction than other solvents. Theconcentration of a soluble fraction obtained with a specificsolvent has been found to relate closely to the performa
10、ncecharacteristics of a product in certain applications, for examplefilm and fiber. Data obtained by one solvent and at oneprecipitation time cannot be compared with data obtained byanother solvent or precipitation time, respectively.6. Interferences6.1 It is possible that materials with solubilitie
11、s similar tothe soluble fraction, such as additives, can interfere with themeasurement of solubles. When present in concentrations thatare judged to impart a significant error to the soluble-fractiondata, the level of interference must be determined and correc-tions made.6.2 It is possible that smal
12、l-particle fillers and pigments andinsoluble gels present in the polymer can pass through the filterand cause errors in the measurement.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.1This test me
13、thod is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-als.Current edition approved Aug. 1, 2010. Published September 2010. Originallyapproved in 1994. Last previous edition approved in 2006 as D5492 - 06. DOI:1
14、0.1520/D5492-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards I
15、nstitute (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 Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Apparatus7.1 Reflux-Condenser Apparatus, 400 mm, with
16、24/40 glassjoint.7.2 Flat-Bottom 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 b
17、lockcapable of maintaining 145 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, Wha
18、tman No. 4, No. 541,4orequivalent, 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 Analy
19、tical Balance, with minimum 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
20、)Assay gaschromatography (GC) = 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, evapora
21、tion residue at 140Cless than 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 and the level of ethyl-benzene is less than 2 %.8.3 Reagent grade ortho-xylene shall be used as the refer-ence solvent whene
22、ver there is a dispute between laboratorieson test results, unless the laboratories agree otherwise.9. Procedure9.1 Preparation of the Xylene:9.1.1 Stabilization of the xylene is not required.NOTE 3When testing non-stabilized polypropylene powders orspheres, antioxidants may be added to prevent degr
23、adation. This additionis optional if previous testing has shown there is no significant change inxylene soluble level.NOTE 4Butylated hydroxyl toluene (BHT), 4,4 thiobis (6-tert-butyl-m-cresol), or tetrakis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamate) meth-ane at an approximate concentration of 0.02
24、 g/L of xylene have beenfound 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 xyl
25、ene. Using nitrogen gas, purge 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.
26、 A solvent-blanktest for residue shall 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.9.2.2 If the xylene is an extra pure grade (minimum 99.5 %)and is used within three days after being opened
27、, the determi-nation of the blank is not required. If used after three days afterbeing opened, a solvent blank must be run.NOTE 5It 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 l
28、arger size may be used ifthe xylene is used up within a short period of time. The purpose of theshort time period is to ensure purity and minimize moisture pickup andother contaminants.9.2.3 Pipet 200 mL of unstabilized or stabilized xylene intoa clean empty flask.9.2.4 Place a 125-mm diameter or la
29、rger No. 4 filter paperor equivalent in a 125-mm diameter of larger funnel in a funnelrack over a 250-mL glass-stoppered flask.9.2.5 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
30、has beencollected.9.2.6 Dry the aluminum pans (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.9.2.7 With a Class A pipet, pipet a 100-mL aliquot of the
31、filtered xylene into the weighed pan.9.2.8 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
32、dry.9.2.9 Place the pan into a vacuum oven at 100 6 10C at apressure less than 13.3 kPa for a known suitable time whereconstant weight is observed.9.2.10 Cool the pan to room temperature in a desiccator fora minimum of 15 minutes and weigh the pan to the nearest0.0001 g. Calculate the average blank-
33、residual mass of thethree determinations.9.3 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
34、you are aware of alternative suppliers,please 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.D5492 1029.3.1 Dry the polypropylene powder or spheres beforeanalysis.
35、 It is not necessary to dry the pellets unless 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,
36、 where there is concern that thepolymer sample 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 materia
37、l shall be dried as specified in9.3.1.9.3.2 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 s
38、ample size. Determine mass of thesample to the nearest 0.0001 g. Pour the sample into aflat-bottom boiling flask. Place a magnetic stirring bar in theflask.9.3.3 Table 1 provides a choice of sample mass. Use thelargest sample mass possible to minimize variability of the testdata, unless from prior e
39、xperience it is known that thepolymer/xylene solution does not filter readily as in 9.3.15.9.3.4 Pipet 200 mL of unstabilized or stabilized xylene intothe flask.9.3.5 Attach the flask to the condenser.9.3.6 Place an insulation disk on top of the electromagneticstirrer plate to prevent localized heat
40、ing of the flask. Positionthe flask and condenser 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.9.3.7 Blanket the contents of the boiling flask with a slowflow of nitrogen directed across the
41、top of the condenser, notdirectly into the condenser, to minimize possible xylene loss.Nitrogen flow rate shall be approximately 2 L/h.9.3.8 Heat the polymer/xylene mixture to reflux temperaturewhile vigorously stirring. The stirring shall be vigorous enoughto obtain a deep vortex, which keeps the b
42、oiling under controland prevents boiling up into the condenser. Ensure that thereflux is gentle so that localized burning and sticking of thepolymer to the flask walls does not occur.9.3.9 Once the reflux temperature is reached, stir the solu-tion for an additional 30 min. The liquid will appear wat
43、er-clear.9.3.10 Remove the heating plate from 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
44、that thesolution is cooled to within a narrow range of temperature fromrun to run.9.3.11 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.9.3.12 The water bath shall have sufficient co
45、oling capacityto maintain a constant temperature of 25 6 0.5C duringcooling.NOTE 7Do not shake the flask while the xylene-polymer solution isstill hot as this may create a safety hazard.NOTE 8Because the rate of cooling affects the crystal size and the rateof crystallization, the time and temperatur
46、e during the cooling steps arevery critical to the final test result.9.3.13 Precipitation Time9.3.13.1 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
47、to 32 min. Remove the flaskfrom the temperature-controlled bath. Stir or gently shake theflask to break up any precipitated-polymer gel.NOTE 9Shorter precipitation times (for example, comparing 30 min-utes versus 60 minutes or longer) lead to higher values of soluble contentfor propylene plastics. U
48、sers of this method should be warned that productspecification ranges may need to be adjusted in order to compensate forthese differences.NOTE 10With the shorter 30 minute precipitation time, a true equi-librium will not be reached. Consequently, it is very critical that both theprecipitation time a
49、nd cooling temperature be controlled very precisely tominimize variance.9.3.14 Place a 125-mm diameter or larger No. 4 filter paperor equivalent in a 125-mm diameter or 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 9.3.3.FIG. 1 Equipment SetupD5492 1039.3.15 For each sample, pour the contents from the flaskinto a funnel and allow the filtrate to drip into the second flask.NOTE 11With some materials that may have bee
