ASTM-D792
ADOPTION NOTICE
ASTM-D792, "DENSITY AND SPECIFIC GRAVITY (RELATIVE DENSITY) OF
PLASTICS BY DISPLACEMENT", was adopted on 15-JUL-91 for u by
the Department of Defen (DoD). Propod changes by DoD
activities must be submitted to the DoD Adopting Activity:
Commander, Defen Supply Center Philadelphia, ATTN: DSCP-ILEA,
700 Robbins Avenue, Philadelphia, PA 19111-5096. Copies of this
document may be purchad from the American Society for Testing
and Materials 100 Barr Harbor Drive West Conshohocken,
____________________ Pennsylvania, United States, 19428-2959. www.astm/
白玫瑰的寓意
-
-`-`-`,,`,,`,`,,`---
Custodians:Adopting Activity:
DLA - IS
Army - MR
Navy - SH
Air Force - 11
DLA - GS
Reviewer Activities:
Navy - YD
FSC 9330
DISTRIBUTION STATEMENT A:Approved for public relea; distribution
is unlimited.
Copyright ASTM International
Provided by IHS under licen with ASTM
Not for Resale
No reproduction or networking permitted without licen from IHS
immersion is determined,and its specific gravity(relative density)calculated.
5.Significance and U
5.1The specific gravity or density of a solid is a property that can be measured conveniently to identify a material,to follow physical changes in a sample,to indicate degree of uniformity among diff
erent sampling units or specimens,or to indicate the average density of a large item.
5.2Changes in density of a single specimen may be due to changes in crystallinity,loss of plasticizer,absorption of solvent,or to other caus.Portions of a sample may differ in density becau of difference in crystallinity,thermal history, porosity,and composition(types or proportions of resin, plasticizer,pigment,orfiller).
N OTE6—Reference is made to Test Method D1622.
5.3Density is uful for calculating strength-weight and cost-weight ratios.
6.Sampling
6.1The sampling units ud for the determination of spe-cific gravity(relative density)shall be reprentative of the quantity of product for which the data are required,in accordance with Practice D1898.
6.1.1If it is known or suspected that the sample consists of two or more layers or ctions having different specific gravities,either completefinished parts or complete cross ctions of the parts or shapes shall be ud as the specimens, or parate specimens shall be taken and tested from each
layer.The specific gravity(relative density)of the total part cannot be obtained by adding the specific gravity of the layers, unless relative percentages of the layers are taken into account.
7.Conditioning
7.1Conditioning—Condition the test specimens at 2362°C and5065%relative humidity for not less than40 h prior to test in accordance with Procedure A of Practice D618,unless otherwi specified by the contract or relevant material specifications.In cas of disagreement,the tolerances shall be61°C and62%relative humidity.
7.2Test Conditions—Conduct tests in the standard labora-tory atmosphere of2362°C and5065%relative humidity, unless otherwi specified in this specification or by the contract or relevant material specification.In cas of disagree-ment,the tolerances shall be61°C and62%relative humid-ity.
TEST METHOD A FOR TESTING SOLID PLASTICS IN WATER(SPECIMENS1TO50g)
8.Scope
8.1This test method involves weighing a one-piece speci-men of1to50g in water,using a sinker with p
lastics that are lighter than water.This test method is suitable for plastics that are wet by,but otherwi not affected by water.
9.Apparatus
9.1Analytical Balance—A balance with a precision within 0.1mg,accuracy within0.05%relative(that is,0.05%of the mass of the specimen in air),and equipped with a stationary support for the immersion vesl above the balance pan(“pan straddle”).
N OTE7—Assurance that the balance meets the performance require-ments should be provided by frequent checks on adjustments of zero point and nsitivity and by periodic calibration for absolute accuracy,using standard mass.
9.2Sample Holder,corrosion-resistant(for example,wire, gemholder,etc.).
9.3Sinker—A sinker for u with specimens of plastics that have specific gravities less than1.000.The sinker shall:(1)be corrosion-resistant;(2)have a specific gravity of not less than 7.0;(3)have smooth surfaces and a regular shape;and(4)be slightly heavier than necessary to sink the specimen.The sinker should have an opening to facilitate attachment to the specimen and sample holder.
9.4Immersion Vesl—A beaker or other wide-mouthed vesl for holding the water and immerd specimen.
9.5Thermometer—A thermometer with an accuracy of 60.1°C is required.
关于花10.Materials
10.1Water—The water shall be substantially air-free and distilled or demineralized water.
N OTE8—Water may be rendered substantially air-free by boiling and cooling or by shaking under vacuum in a heavy-walled vacuumflask. (Precaution:U gloves and shielding.)If the water does not wet the specimen,a few drops of a wetting
agent shall be added.If this solution does not wet the specimen,Method B shall be ud.
11.Test Specimen
11.1The test specimen shall be a single piece of the material under test of any size and shape that c
an conveniently be prepared and tested,provided that its volume shall be not less than1cm3and its surface and edges shall be made smooth.The thickness of the specimen should be at least1mm for each1 g of weight.A specimen weighing1to5g usually will be found convenient,but specimens up to approximately50g may be ud(Note9).Care should be taken in cutting specimens to avoid changes in density resulting from compressive stress or frictional heating.
N OTE9—Specifications for certain plastics require a particular method of specimen preparation and should be consulted if applicable.
11.2The specimen shall be free from oil,grea,and other foreign matter.
12.Procedure
12.1Measure and record the water temperature.
12.2Weigh the specimen in air to the nearest0.1mg for specimens of mass1to10g or to the nearest mg for specimens of mass more than10to50g.
12.3If necessary,attach to the balance a piece offine wire sufficiently long to reach from the hook above the pan to the support for the immersion vesl.In this ca attach the specimen to the wire s
uch that it is suspended about25mm above the vesl support.
N OTE10—If a wire is ud the specimen may be weighed in air after hanging from the wire.In this ca,record the mass of the specimen,
a =(mass of specimen +wire,in air)−(mass of wire in air).
12.4Mount the immersion vesl on the support,and
completely immer the suspended specimen (and sinkers,if
ud)in water (10.1)at a temperature of 2362°C.The vesl
初中故事
must not touch sample holder or specimen.Remove any
bubbles adhering to the specimen,sample holder,or sinker,
paying particular attention to holes in the specimen and sinker.
Usually the bubbles can be removed by rubbing them with a
wire.If the bubbles cannot be removed by this method or if
bubbles are continuously formed (as from dissolved gas),the
u of vacuum is recommended (Note 12).Determine the mass
of the suspended specimen to the required precision (12.2)
(Note 11).Record this apparent mass as b (the mass of the
specimen,sinker,if ud,and the partially immerd wire in
liquid).Unless otherwi specified,weigh rapidly in order to
minimize absorption of water by the specimen.
N OTE 11—It may be necessary to change the nsitivity adjustment of母亲生日贺卡
the balance to overcome the damping effect of the immerd specimen.
N OTE 12—Some specimens may contain absorbed or dissolved gas,
or irregularities which tend to trap air bubbles;any of the may affect the
density values obtained.In such cas,the immerd specimen may be
subjected to vacuum in a parate vesl until evolution of bubbles has
substantially cead before weighing (e Test Method B).It must also be
demonstrated that the u of this technique leads to results of the required
degree of precision.12.5Weigh the sample holder (and sinker,if ud)in water
with immersion to the same depth as ud in the previous step
13.Calculation 13.1Calculate the specific gravity of the plastic as follows:sp gr 23/23°C 5a /~a 1w 2b !where:a =apparent mass of specimen,without wire or sinker,in air,b =apparent mass of specimen (and of sinker,if ud)completely immerd and of the wire partially im-merd in liquid,and w =apparent mass of totally immerd sinker (if ud)and of partially immerd wire.13.2Calculate the
density of the plastic as follows:D 23C ,kg/m 35sp gr 23/23°C 3997.513.3If the temperature of the water is different than 23°C,the following equations will be ud:M 5D D /D t (1)D –~conversion to 23°C !,kg/m 35sp gr t a /t w 3@997.51~t w –23!3M #(2)sp gr 23/235D ~conversion to 23°C !/997.5(3)
where:M =slope,D D =difference between the lowest and highest tempera-ture tolerance for the standard density of water (D @A S r =within laboratory standard deviation for the individual material.It is obtained by pooling the within-laboratory standard deviations of the test results from all of the participating laboratories:
S r =[[(s 1)2+(s +(s n )2]/n]1/2
B S R =between-laboratories reproducibility,expresd as standard deviation:S R =[S r 2+S L 2]1/2where S L is the standard deviation of laboratory means.
C r =within-laboratory critical interval between two test results =2.83S r .
D R =between-laboratories critical interval between two test results =2.83S R .
different layers or areas of a nonhomogeneous product,
14.1.4Report the temperature of the water.
14.1.5Report the density and specific gravity with four
significant figures.
14.1.6Any evidence of porosity of the material or speci-
men,
14.1.7The method of test (Method A of Methods D 792),
and
14.1.8Date of test.
15.Precision and Bias
15.1See Section 23.
TEST METHOD B FOR TESTING SOLID PLASTICS
IN LIQUIDS OTHER THAN WATER (SPECIMENS 1
TO 50g)
16.Scope
16.1Test Method B us a liquid other than water for testing
one-piece specimens,1to 50g,of plastics that are affected by
water or which are lighter than water.
17.Apparatus
17.1The apparatus shall include the balance,wire,and
immersion vesl of Section 8,and,optionally,the following:
17.2Pycnometer with Thermometer —A 25-mL specific
gravity bottle with thermometer,or
17.3Pycnometer —A pycnometer of the Weld type,prefer-
ably with a capacity of about 25mL and an external cap over
the stopper.
17.4Thermometer —A thermometer having ten divisions
孩子孤独症per degree Celsius over a temperature range of not less than
5°C or 10°F above and below the standard temperature,and
having an ice point for calibration.A thermometer short
enough to be handled inside the balance ca will be found
convenient.ASTM Thermometer 23C (e Specification E 1)
and Anschütz-type thermometers have been found satisfactory巍峨什么意思
for this purpo.17.5Constant-Temperature Bath —An appropriate constant-temperature bath adjusted to maintain a temperature of 2360.1°C.18.Materials 18.1Immersion Liquid
—The liquid ud shall not dissolve,swell,or otherwi affect the specimen,but should wet it and sho
uld have a specific gravity less than that of the specimen.In addition,the immersion liquid should be nonhygroscopic,have a low vapor pressure,a low viscosity,and a high flash point,and should leave little or no waxy or tarry residue on evaporation.A narrow cut distilled from kerosine meets the requirements for many plastics.The specific gravity 23/23°C of the immersion liquid shall be determined shortly before and after each u in this method to a precision of at least 0.1%relative,unless it has been established experimentally in the particular application that a lesr frequency of determination can be ud to assure the desired precision.N OTE 15—For the determination of the specific gravity of the liquid,the u of a standard plummet of known volume (Note 15)or of Method A,C,or D of Test Methods D 891,using the modifications required to give specific gravity 23/23°C instead of specific gravity 60/60°F,is recom-mended.One suggested procedure is the following:If a constant-temperature water bath is not available,deter-mine the mass of the clean,dry pycnometer with thermometer to the nearest 0.1mg on an analytical balance.Fill the pycnometer with water (10.1)cooler than 23°C.Inrt the thermometer-stopper,causing excess water to be expelled through the side arm.Permit the filled bottle to warm in air until the thermometer reads 23.0°C.Remove the drop of water at the tip of the side arm with a bit of filter paper,taking care not to draw any liquid from within the capillary,place the cap over the side arm,wipe the outside carefully,and determine the mass of the filled bottle again to the nearest 0.2mg.Empty the pycnomet
er,dry,and fill and determine the mass with the other liquid in the same manner as was done with the water.
TABLE 2Test Method B
Specific Gravity Tested in Liquids Other Than Water Material
Mean S r A S R B r C R D Polypropylene
0.90230.001390.002390.003930.00676LDPE
0.92150.001090.001950.003080.00552HDPE
0.96780.001260.001890.003560.01007Thermot清淋颗粒
1.31300.001600.002170.004530.01282A S r =within laboratory standard deviation for the individual material.It is obtained by pooling the within-laboratory standard deviations of the test results from all of the participating laboratories:
S r =[[(s 1)2+(s +(s n )2]/n]1/2
B S R =between-laboratories reproducibility,expresd as standard deviation:S R =[S r 2+S L 2]1/2where S L is the standard deviation of laboratory means.
C r =within-laboratory critical interval between two test results =2.83S r .
D R =between-laboratories critical interval between two test results =2.83S R .
TABLE 3Standard Density of Water A
°C
r /kg m –30.0
0.10.20.30.40.50.60.70.80.921
997.994897319513929490738852863084068182795722
997.773075037275704568156584635161185883564823
997.541251744936469744564215397337303485324024
997.299427472499225020001749149712440990073525
997.048002239965B 9707B 9447B 9186B 8925B 8663B 8399B 8135B A
Obtained from CRC Handbook of Chemistry and Physics ,78th edition,1997-1998.B The leading figure decreas by 1.
Calculate the specific gravity23/23°C of the liquid,d,as follows:
d5~b2e!/~w2e!
where:
e=apparent mass of empty pycnometer,
w=apparent mass of pycnometerfilled with water at
23.0°C,and
b=apparent mass of pycnometerfilled with liquid at
23.0°C.
If a constant-temperature water bath is available,a pycnom-eter without a thermometer may be ud(compare30.2).
N OTE16—One standard object which has been found satisfactory for this purpo is the Reimann Thermometer Plummet.The are normally supplied calibrated for measurements at temperatures other than23/23°C, so that recalibration is necessary for the purpos of the methods. 19.Test Specimen
19.1See Section11.
20.Procedure
20.1The procedure shall be similar to Section12,except for the choice of immersion liquid,and the temperature during the immerd weighing(12.3)shall be2360.5°C.
21.Calculation
21.1The calculations shall be similar to Section13,except that d,the specific gravity23/23°C of the liquid,shall be placed in the numerator:
Sp gr23/23°C5~a3d/~a1w2b!
22.Report
22.1See Section14.
23.Precision and Bias
23.1Tables1and2are bad on an interlaboratory study8conducted in1985in accordance with Practice E691,involv-ing5materials tested with Test Method A by6laboratories or 4materials tested with Test Method B by6laboratories.Each test result was bad on two individual determinations and each laboratory obtained four test results for each material.
N OTE17—Caution:The explanations of r and R are only intended to prent a meaningful way of considering the approximate precision of the test methods.The data of Tables1and2should not be applied to acceptance or rejection of materials,as the data apply only to the materials tested in the round robin and are unlikely to be rigorously reprentative of other lots,formulations,conditions,materials,or labo-ratories.Urs of this test method should apply the principles outlined in Practice E691to generate data specific to the materials and laboratory(or between specific laboratories).The principles of23.2-23.2.3would then be valid for such data.
23.2Concept of r and R in Tables1and2—If S r and S R have been calculated from a large enough body of data,and for test results that were averages from4test results for each material,then:
23.2.1Repeatability—Two test results obtained within one laboratory shall be judged not equivalent if they differ by more than the r value for that material.The concept r is the interval reprenting the critical difference between two test results for the same material,obtained by the same operator using the same equipment on the same day in the same laboratory. 23.2.2Reproducibility—Two test results obtained by differ-ent laboratories shall be judged not equivalent if they differ by more than the R value for
that material.The concept R is the
interval reprenting the critical difference between two test
results for the same material,obtained by different operators
using different equipment in different laboratories.
23.2.3Any judgment in accordance with23.2.1or23.2.2
would have an approximate95%(0.95)probability of being
correct.
23.3There are no recognized standards by which to esti-
mate bias of this test method.
24.Keywords
空调维修工具24.1density;relative density;specific gravity
SUMMARY OF CHANGES
Committee D20has identified the location of lected changes to the test methods since the last issue that
may impact the u of the test methods.
D792–98:
(1)An ISO equivalency statement(Note2)was added and subquent notes were renumbered.
(2)Practice E380was added to the text.
(3)Paragraph9.2was revid to include the identification of a sample holder.
(4)“And”was added to10.1.
(5)Paragraphs12.1and14.1.4were added and subquent paragraphs were renumbered.
(6)“I r”and I R were changed to“r”and“R”in Tables1and2.
(7)Section23was rewritten.
D792–00:(1)Changed Note2from“There is no similar or equivalent ISO standard”to“This standard is not equivalent to ISO1183 Method A.”
(2)Deleted reference to Note2in3.2.2.
(3)Changed1°C to61°C in7.1.
(4)Changed“if the wire is ud”to“if a wire is ud”in Note 13.
(5)Changed the correction factor from997.6to997.5in Note 5and13.2.
(6)Replaced“wire”with“sample holder”in9.3.
(7)Changed accuracy from1°C to0.1°C in9.5.
(8)Deleted“if the test is not performed in the standard
8Supporting data are available from ASTM Headquarters.Request RR:D20-1133.
