GB/T 4688-2020 in English

《GB/T 4688-2020纸、纸板和纸浆 纤维组成的分析》由TC141（全国造纸工业标准化技术委员会）归口，主管部门为中国轻工业联合会。

GB/T 4688-2020 Paper, board and pulp - Analysis of fiber furnish

Warning: Persons using this standard shall be familiar with normal laboratory practice. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.

1 Scope

This standard specifies the method fiber furnish analysis of paper, board and pulp.

This standard applies to all kinds of pulp, and to paper and board other than heavily impregnated or highly colored.

Note: Heavily impregnated or highly colored paper and board cannot be dispersed or decolored without affecting the structure or the staining reactions of the fibers.

2 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

2.1
fiber coarseness
mass per unit length for a particular type of fiber (oven-dry weight).

Note: This is expressed in milligrams per meter (mg/m).

2.2
weight factor
ratio of the fiber coarseness of a particular type of fiber to that of a reference (given) fiber

Note: Traditionally, cotton fiber was selected as the reference fiber to which all other fibers were compared. The weight factor of cotton fiber was taken as 1.00, and the fiber coarseness of that fiber was determined to be 0.180 mg/m. The weight factor, f, of a particular type of fiber can be derived from its fiber coarseness by comparison with the fiber coarseness of cotton, as derived by the expression (1):

(1)

where,

f—the weight factor;

c—the fiber coarseness, in milligrams per meter (mg/m).

3 Principle

The fiber furnish analysis is carried out under the microscope or with the fiber analyzer on a small quantity of stained fibers representative of the sample being tested: qualitatively, on the basis of the stain reactions and the morphological characteristics of the fibers; quantitatively, by counting the number of crossings of various kinds of fibers with the counting line and by transforming the number of counts into the percentages by weight by the application of weight factors.

4 Reagents

Unless otherwise stated, during the analysis, use only reagents of recognized analytical grade and only distilled water or deionized water, or water of equivalent purity.

4.1 Sodium hydroxide (NaOH) solution, about 1% (m/m), containing 10g sodium hydroxide per litre.

4.2 Hydrochloric acid (HCl) solution, about 0.2% (m/m), containing 5mL of hydrochloric acid per litre.

4.3 Phosphoric acid (H3PO4) solution, about 5% (m/m), containing 35mL of 85% (m/m) phosphoric acid per litre.

4.4 Aluminum sulfate [Al2(SO4)3] solution, about 5% (m/m), containing 50 g of aluminium sulfate per litre.

4.5 Potassium permanganate (KMnO4) solution, about 6.5% (m/m), containing 65 g of potassium permanganate per litre.

4.6 Oxalic acid (C2H2O4·2H2O) solution, about 5% (m/m), containing 50 g of oxalic acid per litre.

4.7 Organic solvents: ethanol (C2H5OH), diethyl ether (C2H5OC2H5), ethyl acetate (CH3COOC2H5), acetone (CH3COCH3), xylene [C6H4(CH3)2], toluene (C6H5CH3), chloroform (CHCl3), tetrachloroethene (C2Cl4) and trichloroethane (C2H3Cl3).

5 Apparatus

5.1 Microscope

It shall be equipped with a mechanical stage objective lens, eyepiece with cross micrometer, and daylight LED lamp or normal vacuum lamp with daylight filter.

Note: For the identification and counting of fibers, a magnification of ×40 to ×120, and for the study of structural details, ×200 to ×500 is recommended.

5.2 Fiber analyzer

It consists of an imaging system and a measurement system. The imaging system includes a microscope and a digital imaging acquisition unit; the measurement system includes an image transmission and conversion unit and a measurement and analysis unit.

5.3 Disperser

It is intended for easily dispersible samples, e.g., agitator, ultra-sonic disperser and high-speed macerator.

5.4 Infra-red lamp, or hot-plate

It shall be capable of being maintained at 50℃ to 60℃.

5.5 Filtering devices

5.5.1 Glass filter: 200mL, with sintered disc, pore size 15μm to 40μm or with screen, aperture diameter 15μm to 40μm.

5.5.2 Round sieve, diameter 50 mm to 70 mm, with metal or plastic edge, height about 10 mm. The sieve bottom shall be made of woven wire cloth, aperture size 60μm to 80μm.

5.6 Dropper

The internal diameter of the outlet of the dropper is 5mm to 8mm, and the wall of the tube shall have marks of 0.5mL and 1.0mL.

5.7 Microscope slides

The size of the slide is 25mm×75mm, with the thickness of 1mm or 2mm.

5.8 Microscope cover glasses

Recommended size: 22mm × 22mm or 20mm × 20mm.

5.9 Dissecting needles

They shall be made of stainless steel.

5.10 Petri dishes

Petri dishes, or shallow covered dishes, approximately 100mm to 120mm in diameter.

5.11 Counter

A multi-stage decimal counter that can record multiple sets of data.

5.12 Dropper bottles

30mL or 50mL.

5.13 Beakers

Foreword i
1 Scope
2 Terms and definitions
3 Principle
4 Reagents
5 Apparatus
6 Preparation of the test piece
7 Staining and preparation of fiber slides
8 Test procedure
9 Expression of results
10 Test report
Annex A (Informative) List for cross-reference to clauses/subclauses between this standard and ISO 9184-1:1990, ISO 9184-2:1990, ISO 9184-3:1990, ISO 9184-4:1990, ISO 9184-5:1990
Annex B (Normative) Staining guide
Annex C (Normative) Herzberg staining test
Annex D (Normative) Graff "C" staining test
Annex E (Normative) Lofton-Merritt staining test
Annex F (Informative) Reference weight factors by fiber species