Analysis Of Standard And Method For Quantitative Detection Of Cotton And Flax

In the present cotton,

1 cotton and flax quantitative

At present, the standard for the quantitative detection of cotton and linen blended fabrics is the FZ/T3003 - 2000 "microscopic projection method for quantitative analysis of hemp and cotton blended products".

However, according to the quantitative analysis of the standard formula, the deviation of some results can be very large. This deviation is different from the content, generally from 2% to 10%.

Such a large error not only exceeds the error range stipulated in the fiber content standard, but also challenges the significance of cotton and linen content test itself.

So what is the reason for such a big deviation?

In the exchange with peers, they also encountered similar situations in testing. This shows that the calculation and correction according to the above standards may be a problem.

With this question, we conducted a comparative analysis experiment, trying to find new correction coefficients, so that the calculation results are closer to the true value.

2 experimental situation

Flax and cotton are cellulose fibers. After blending, they can not be determined by chemical analysis, nor can they be separated by mechanical means.

This method uses ordinary biological microscope, micro projector or digital fiber fineness instrument to distinguish and count a certain number of fibers, and measure the diameter or cross-sectional area of fiber by means of a micro projector or digital fiber fineness instrument, so as to calculate the weight percentage of various fibers.

On the experimental samples, in order to be able to reflect the different proportions of cotton and linen blended, the cotton and linen blend was set at 5% to 95% by weight method, and the interval was 5%.

2.1 experimental operation

Preparation of 2.1.1 slides

In strict accordance with the requirements of FZ/T 1057.3 - 1999 "microscopic observation method for textile fiber identification test method", the above dyed samples were evenly cut from 0.2mm~0.36 mm long fiber bundles with the fiber slicer and moved to the surface pan, adding a certain amount of glycerol without water, and fully mixed into dense suspension.

Use a wide mouth suction tube to absorb a small amount of mixed and uniform suspension on the glass slide, unfold it evenly, cover the cover glass to fix the sample, and note that the fiber can not be put outside the cover glass to avoid loss of fiber, otherwise, the glass slides should be re prepared.

Count of 2.1.2 fiber root number

The fibers were observed by an ordinary biological microscope or a microprojector.

The prepared slides were placed on an ordinary biological microscope with a cross eyepiece and a magnifying magnification of 200 to 250 times, or a magnification 500 times microprojector stage. All kinds of fibers entering the field of vision were observed through eyepiece, and their types were identified according to the morphological and structural characteristics of fibers (see Appendix C and fiber morphology photos).

Count from the top corner or the bottom corner near the view.

When the slides move horizontally along the horizon, all fibers are identified and counted through the center of the eyepiece cross.

After crossing every field of vision, slide the glass slide vertically 1 mm~2 mm and then move slowly across the horizon, identify and count the fibers, repeat the procedure until all the slides are finished, and the total count should be more than 1000.

If the number of roots in the glass slides exceeds 1000, the glass slides must be counted in the whole range. If the glass slides are less than 1000 in the whole range, another glass slide should be made, so that the total number of accumulated fibers will reach more than 1000.

Each batch of samples counted more than 1000 fibers in two groups. The number of converted roots of each fiber in the two groups was calculated. The difference between the number of converted roots per fiber was not greater than 10 in the two test.

Determination of 2.1.3 fiber diameter

The microprojector is calibrated to magnify to 500 times the projected plane, and then the prepared slides are loaded on the stage to make the measured fibers in the projection circle of the microprojector.

Adjust the projector's fine adjustment so that the edge of the fiber image is projected onto the wedge ruler as a thin line, and the projection width of the middle length of the fiber is measured as the diameter.

But do not measure those fibers at the intersection of two fibers and those that are shorter than 150 m, measuring 200 or more of each type of fiber.

After calculating, the average diameter of each fiber is calculated.

2.2 applicable formula

The experimental results are based on the standard formula in the FZ/T3003 - 2000 "micro projection method for quantitative analysis of ramie cotton blended products" (no longer listed in the text).

In the process of forming this article, my colleague recommended an article about the standard draft for solicitation.

In this paper, the formula is revised on the basis of the original standard.

3 Analysis of test results

The test results are expressed on the average of the two tests. If the difference between the two test results is greater than 2%, third tests should be carried out, and the test results are expressed on the average of three tests.

The test results were revised to two after decimal places according to GB/T 8170 (see Table 1, table 2).

Table 1 comparison with current standard calculation results

Splitting method flax

Content /% experiment operation

Result /% error /%