CN110487669A - The method for measuring polyethylene pellet density - Google Patents
The method for measuring polyethylene pellet density Download PDFInfo
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- CN110487669A CN110487669A CN201810462912.9A CN201810462912A CN110487669A CN 110487669 A CN110487669 A CN 110487669A CN 201810462912 A CN201810462912 A CN 201810462912A CN 110487669 A CN110487669 A CN 110487669A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/02—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity by measuring weight of a known volume
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Abstract
The present invention relates to polyethylene fields, disclose the method for measurement polyethylene pellet density.Method includes the following steps: (1) is full of inert gas under conditions of closed and steady temperature, by container A, the pressure P in container A is measured0；(2) polyethylene pellet that the unknown weight of density is M is placed in sample bin B and closed, is then connected to sample bin B with container A, pressure P when measurement equilibrium state1, wherein polyethylene pellet density is calculated by formula (I), wherein a, b are calibration factor, V1For the volume of sample bin B, V0For the volume of container A.Method have quickly, accurate, the labor intensity of operator is low, as a result repeatability is high, and environmental-friendly advantage,
Description
Technical field
The present invention relates to polyethylene fields, and in particular to the method for measurement polyethylene pellet density.
Background technique
Density is the important indicator of polyethylene production.
Density of pe test is all made of the GB/T 1033.2-2010 " measurement the 2nd of the non-foam plastic density of plastics at present
Part: density gradient column method ".This method is based on Archimedes' principle:
1. first having to prepare density gradient column, general 1 time/month, single prepares 24 hours time-consuming or more, pure manual operation；
2. sample treatment:
2.1 are melted using melting means instrument and are squeezed into cylindrical batten；
2.2 above-mentioned battens are annealed 30 minutes in the distilled water of boiling, then are cooled down 60 minutes at room temperature；
2.3 batten dissections are about 0.5cm, and are soaked with light liquid.
3. test visually must persistently track batten 15 minutes in density gradient column, and record 15 minutes positions.
4. result calculates.
Therefore GB/T 1033.2-2010 is complex for operation step, manual operations mostly, large labor intensity.It must be artificial
Particles fall situation is tested in observation in continuous 15 minutes, and the drop-off positions of particle were determined at 15 minutes.Due to former in gradient column
There is the interference of particle, asthenopia, inevitable appearance position misjudgment easily occurs in tester.Do not consider that density gradient column is matched
System, single sample are 4 hours or so time-consuming.
CN1373353A discloses the device and method that polyethylene and acrylic resin density are measured under room temperature, but the party
Method needs to pre-process sample to be detected, and uses organic solvent isopropanol maceration extract, and measurement is both needed to again every time
With preparing isopropanol maceration extract, not environmentally, whole process needs manual operation, and sample levitation position is difficult to control, in addition sample
The pretreated time, single sample test time-consuming was more than 2 hours.
Alternatively, existing instrumental method surveys density of solid.But accuracy of instrument is inadequate, measurement result at most may be only accurate to thousand points
Position (g/cm3), and test repeatability cannot meet GB/T 1033.2-2010, can not meet polyethylene demand of industrial production.
To sum up, the method for existing GB/T 1033.2-2010 test polyethylene pellet density, there are complex for operation step,
Mostly manual operations, large labor intensity, not environmentally the problem of.For existing instrumental method density of solid, and there are results
The bad problem of repeatability.
Summary of the invention
The purpose of the invention is to overcome it is of the existing technology cannot quickly, accurately measure, operator when measurement
Labor intensity it is high, measurement result poor repeatability, not environmentally the problem of, the method for measurement polyethylene pellet density, the party are provided
Method is with quick, accurate, the labor intensity of operator is low, as a result repeatability height, and environmental-friendly advantage.
To achieve the goals above, the present invention provides a kind of methods for measuring polyethylene pellet density, wherein the side
Method the following steps are included:
(1) under conditions of closed and steady temperature, container A is full of inert gas, measures the pressure P in container A0；
(2) polyethylene pellet that the unknown weight of density is M is placed in sample bin B and closed, then by sample bin B and held
Device A connection, measures pressure P when equilibrium state1,
Wherein, polyethylene pellet density is calculated by formula (I),
Wherein, a, b are calibration factor, V1For the volume of sample bin B, V0For the volume of container A.
Preferably, a, b calculation method the following steps are included:
(I) under conditions of closed and steady temperature, inert gas is injected into container A, the pressure in container A is P0；
Weighing known density is ρ1Weight be M1Polyethylene pellet, and polyethylene pellet is placed in sample bin B, closed sample bin
Then sample bin B is connected to by B with container A, measure the pressure P under equilibrium state1,
Wherein, polyethylene pellet density p is calculated by formula (II)1',
(II) method for using step (I) tests x known density as ρxWeight be MxPolyethylene pellet, x are 2 or more
Positive integer, obtain ρ2' to ρx'；
(III) by ρ1' to ρx' to ρ1To ρxLinear fit is carried out, the value of a, b are obtained.
Preferably, the x is 10~20.
Preferably, ρ1To ρxIt is measured by 1033.2 method of GB/T.
Preferably, the inert gas is helium.
Preferably, the steady temperature is 20-40 DEG C.
Preferably, the weight of the M is 2g-4g.
Preferably, the M1Weight be 2g-4g.
Preferably, the MxWeight be 2g-4g.
Preferably, temperature measurement accuracy is 0.01 DEG C, and temperature fluctuation is not more than 0.05 DEG C when constant temperature；Pressure display precision is
0.1Pa, pressure oscillation is not more than 1.0Pa when constant pressure.
By means of the present invention, in addition to weighing sample quality, whole-course automation may be implemented, without artificial on duty, and
And polyethylene pellet, without pretreatment, the testing time of single sample is only 40min or so, the 4 small phases with the prior art
Than working efficiency improves 5 times.It is thereby achieved that the density of polyethylene pellet is detected on quick, accurate, repeatability highland, significantly
The labor intensity of reduction operation personnel.
Moreover, surging condition of the present invention by the measurement accuracy and temperature and pressure of limiting temperature and pressure, test
As a result position (g/cm very much can be accurate to3)。
In addition, the method for the present invention does not use organic solvent, it is safe and environmental-friendly.
Specific embodiment
The endpoint of disclosed range and any value are not limited to the accurate range or value herein, these ranges or
Value should be understood as comprising the value close to these ranges or value.For numberical range, between the endpoint value of each range, respectively
It can be combined with each other between the endpoint value of a range and individual point value, and individually between point value and obtain one or more
New numberical range, these numberical ranges should be considered as specific open herein.
The present invention provides a kind of methods for measuring polyethylene pellet density, wherein the described method comprises the following steps:
(1) under conditions of closed and steady temperature, container A is full of inert gas, measures the pressure P in container A0；
(2) polyethylene pellet that the unknown weight of density is M is placed in sample bin B and closed, then by sample bin B and held
Device A connection, measures pressure P when equilibrium state1,
Wherein, polyethylene pellet density is calculated by formula (I),
Wherein, a, b are calibration factor, V1For the volume of sample bin B, V0For the volume of container A.
According to the method for the present invention, the calculation method of a, b may comprise steps of:
(I) under conditions of closed and steady temperature, inert gas is injected into container A, the pressure in container A is P0；
Weighing known density is ρ1Weight be M1Polyethylene pellet, and polyethylene pellet is placed in sample bin B, closed sample bin
Then sample bin B is connected to by B with container A, measure the pressure P under equilibrium state1,
Wherein, polyethylene pellet density p is calculated by formula (II)1',
(II) method for using step (I) tests x known density as ρxWeight be MxPolyethylene pellet, x are 2 or more
Positive integer, obtain ρ2' to ρx'；
(III) by ρ1' to ρx' to ρ1To ρxLinear fit is carried out, a, b value are obtained.
For example, the sample of 10 known densities of test, density is respectively ρ1、ρ2、ρ3To ρ10, survey by means of the present invention
The density for trying out 10 samples is respectively ρ1’、ρ2’、ρ3' to ρ10', by ρ1' to ρ10' to ρ1To ρ10Carry out linear fit, obtain a,
B value.
According to the method for the present invention, the x can be 2 or more, it is contemplated that accuracy, preferably 10~20.
According to the method for the present invention, ρ1To ρxIt can be measured by 1033.2 method of GB/T.
According to the method for the present invention, the inert gas can be but be not limited to helium.
According to the method for the present invention, the steady temperature can be 20-40 DEG C.The temperature is according to test environment, such as in fact
It tests depending on the environmental condition of room.
According to the method for the present invention, the weight of the M can be but be not limited to 2g-4g.Under the preferred conditions, using energy
4 after decimal point Libras are enough accurate to weigh.Weight greater than 4g can also measure, and only will cause waste,
Weight less than 2g may relatively easily cause error.
According to the method for the present invention, the M1Weight can be but be not limited to 2g-4g.Under the preferred conditions, it uses
4 after decimal point Libras can be accurate to weigh.Weight greater than 4g can also measure, and only will cause wave
Take, the weight less than 2g may relatively easily cause error.
According to the method for the present invention, the MxWeight can be but be not limited to 2g-4g.Under the preferred conditions, it uses
4 after decimal point Libras can be accurate to weigh.Weight greater than 4g can also measure, and only will cause wave
Take, the weight less than 2g may relatively easily cause error.
According to the method for the present invention, in order to improve the accuracy of measurement, the measurement of single polyethylene pellet can repeat to survey
Amount 2 times calculates average value as sample.
According to the method for the present invention, temperature measurement accuracy is 0.01 DEG C, and temperature fluctuation is not more than 0.05 DEG C when constant temperature；Pressure
Display precision is 0.1Pa, and pressure oscillation is not more than 1.0Pa when constant pressure.The measurement accuracy and temperature and pressure of the temperature and pressure
The surging condition of power, measurement result can be accurate to position (g/cm very much3)。
The present invention will be described in detail by way of examples below.
Preparation example 1
20 samples are measured, a, b value are obtained:
(I) under conditions of closed and steady temperature, inert gas is injected into container A, the pressure in container A is P0；
Weighing known density is ρ1Weight be 4.0000g (M1) polyethylene pellet, and polyethylene pellet is placed in sample bin B, it is close
Sample bin B is closed, is then connected to sample bin B with container A, measures the pressure P under equilibrium state1,
Wherein, polyethylene pellet density p is calculated by formula (II)1',
(II) method for using step (I) tests the weight of 19 known densities as 4.0000g (M2To M20Weight be
4g) polyethylene pellet obtains ρ2' to ρ20'；
(III) by ρ1' to ρ20' to ρ1To ρ20Linear fit is carried out, the value for obtaining a, b is respectively 0.12497,0.80654.
Embodiment 1
(1) under conditions of closed and steady temperature, container A is full of inert gas, measures the pressure P in container A0；
It (2) is polyethylene pellet DFDA-7042 (sample 1, the middle petrochemical industry Zhenghai refinery point public affairs of 4g by the unknown weight of density
Department's production) it is placed in sample bin B and closed, then sample bin B is connected to container A, pressure P when measurement equilibrium state1,
Polyethylene pellet density is calculated by formula (I),
Wherein, the value of a, b are respectively 0.12497,0.80654, V1For the volume of sample bin B, V0For the volume of container A.It surveys
Test result is shown in Table 1.
Six repetitive operations are carried out, test result is shown in Table sample 1 in 1.
Embodiment 2
It is tested according to the method for embodiment 1, unlike, using polyethylene pellet M2320 (middle petrochemical industry Zhenghai refinery
Branch company's production), test result is shown in Table sample 2 in 1.
Table 1
It * is the difference of the maximum value of same sample and minimum value.
Can be seen that the method for the present invention by the result of table 1 has preferable repeatability, and test result is credible.
Embodiment 3
It is tested according to the method for embodiment 1, unlike, using polyethylene pellet S-8110 sample rate (middle stone
Change the production of Zhenghai refinery branch company), 16 groups are tested, twice, test result is shown in Table 2 measurement result 1 and measurement knot for every group of test
Fruit 2, and calculate average value.
Comparative example 1
Using the method for GB/T1033.2, polyethylene pellet S-8110 sample rate (middle petrochemical industry Zhenghai refinery point public affairs are measured
Department's production), 16 groups are tested, test result is shown in Table 2.
Table 2
It * is the difference of GB/T1033.2 and average value.
According to the result of table 2, whether there is or not aobvious in 95% confidence interval for calculating GB/T1033.2 method and method of the invention
Write sex differernce:
The difference average value d of two method measured valuesP=[- 0.0002+ (- 0.0004)+...+(- 0.0002)] ÷ 16=-3.7
×10-5
The difference standard deviation S of two method measured valuesd=2.17 × 10-4
T=3.7 × 10-5÷(2.17×10-4÷160.5)=0.68
Look into t table, t0.05,15=2.131 > 0.68, therefore two methods are in 95% confidence interval that there was no significant difference.
Calculate 95% confidence interval of two methods measurement difference
dP±t0.05,15×Sd=(- 3.7 × 10-5)±(4.628×10-4)
In 95% confidence interval, the absolute value of two method differences is respectively less than 0.0005 (g/cm3), it is subjected to.
It can be seen that labor intensity quick using the method for the present invention, accurate, operator by the result of Tables 1 and 2
Low, as a result repeatability is high, and there was no significant difference in 95% confidence interval for method and GB/T1033.2 method of the invention, and
The method of the present invention does not use organic solvent, has the advantages that environmental-friendly.
The preferred embodiment of the present invention has been described above in detail, and still, the present invention is not limited thereto.In skill of the invention
In art conception range, can with various simple variants of the technical solution of the present invention are made, including each technical characteristic with it is any its
Its suitable method is combined, and it should also be regarded as the disclosure of the present invention for these simple variants and combination, is belonged to
Protection scope of the present invention.
Claims (10)
1. a kind of method for measuring polyethylene pellet density, which is characterized in that the described method comprises the following steps:
(1) under conditions of closed and steady temperature, container A is full of inert gas, measures the pressure P in container A0；
(2) polyethylene pellet that the unknown weight of density is M is placed in sample bin B and closed, then by sample bin B and container A
Connection measures pressure P when equilibrium state1,
Wherein, polyethylene pellet density is calculated by formula (I),
Wherein, a, b are calibration factor, V1For the volume of sample bin B, V0For the volume of container A.
2. according to the method described in claim 1, wherein, the calculation method of a, b the following steps are included:
(I) under conditions of closed and steady temperature, inert gas is injected into container A, the pressure in container A is P0；It weighs
Know that density is ρ1Weight be M1Polyethylene pellet, and polyethylene pellet is placed in sample bin B, closed sample bin B, then
Sample bin B is connected to container A, measures the pressure P under equilibrium state1,
Wherein, polyethylene pellet density p is calculated by formula (II)1',
(II) method for using step (I) tests x known density as ρxWeight be MxPolyethylene pellet, x are 2 or more just
Integer obtains ρ2' to ρx'；
(III) by ρ1' to ρx' to ρ1To ρxLinear fit is carried out, the value of a, b are obtained.
3. according to the method described in claim 2, wherein, the x is 10~20.
4. according to the method described in claim 2, wherein, ρ1To ρxIt is measured by 1033.2 method of GB/T.
5. according to the method described in claim 1, wherein, the inert gas is helium.
6. according to the method described in claim 1, wherein, the steady temperature is 20-40 DEG C.
7. according to the method described in claim 1, wherein, the weight of the M is 2g-4g.
8. according to the method described in claim 1, wherein, the M1Weight be 2g-4g.
9. according to the method described in claim 2, wherein, the MxWeight be 2g-4g.
10. temperature measurement accuracy is 0.01 DEG C according to the method described in claim 1, wherein, temperature fluctuation is not more than when constant temperature
0.05℃；Pressure display precision is 0.1Pa, and pressure oscillation is not more than 1.0Pa when constant pressure.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112393941A (en) * | 2020-11-28 | 2021-02-23 | 国网江苏省电力有限公司盐城供电分公司 | Density test method for MPP (modified Polypropylene) or CPVC (chlorinated polyvinyl chloride) cable protection pipe |
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| CN107607672A (en) * | 2017-08-29 | 2018-01-19 | 广州海洋地质调查局 | A kind of underwater gas sensor calibrator (-ter) unit and calibration method |
| CN107843311A (en) * | 2017-11-02 | 2018-03-27 | 李秀水 | A kind of seal volume measurement equipment and method |
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| CN1675533A (en) * | 2002-08-05 | 2005-09-28 | 特罗克斯勒电子实验有限公司 | Determination of envelope volume and density of porous samples |
| CN103822971A (en) * | 2014-03-06 | 2014-05-28 | 北京理工大学 | Resolution detecting and calibrating method for ultrasonic microscope |
| CN104165868A (en) * | 2014-08-25 | 2014-11-26 | 西安近代化学研究所 | Solid propellant smog optical transmittance measuring method |
| CN105784054A (en) * | 2016-03-15 | 2016-07-20 | 中国原子能科学研究院 | System and method suitable for calibrating volume of gas cavity in irregular shape |
| CN107607672A (en) * | 2017-08-29 | 2018-01-19 | 广州海洋地质调查局 | A kind of underwater gas sensor calibrator (-ter) unit and calibration method |
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| CN112393941A (en) * | 2020-11-28 | 2021-02-23 | 国网江苏省电力有限公司盐城供电分公司 | Density test method for MPP (modified Polypropylene) or CPVC (chlorinated polyvinyl chloride) cable protection pipe |
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Application publication date: 20191122 |