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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard is a revision of CJ/T 297-2008 High density polyethylene sheathing compounds for bridge cables. The following main technical changes have been made with respect to CJ/T 297-2008:
——"Classification" is modified (see 3.1);
——"Purpose" is deleted (see 3.3 of Edition 2008);
——"Color" is modified (see 4.1);
——The density index is modified (see 4.3);
——The name of melt flow rate is modified (see 4.3);
——The name and index of impact strength are modified (see 4.3);
——The name of hardness is modified (see 4.3);
——The name of brittleness temperature by impact is modified (see 4.3);
——The item “softening temperature” is deleted (see 4.3 of Edition 2008);
——The item “thermal aging resistance" is deleted (see 4.3 of Edition 2008);
——The item "ozone aging resistance" is deleted (see 4.3 of Edition 2008);
——The item “oxidation induction period at 200℃” is added (see 4.3);
——The time of resistance to fluorescent ultraviolet aging is modified (see 4.3);
——The name and index of carbon black dispersion are modified (see 4.3).
This standard was proposed by the Ministry of Housing and Urban-Rural Development of the People's Republic of China.
This standard is under the jurisdiction of the Technical Committee on Road and Bridge Standardization of MOHURD.
The previous editions of this standard are as follows:
——CJ/T 3078-1998;
——CJ/T 297-2008.
High density polyethylene sheathing compounds for bridge cables
1 Scope
This standard specifies the product classification, specification, requirements, test methods, inspection rules, marking, packaging, transportation and storage of high density polyethylene sheathing compounds for bridge cables.
This standard is applicable to the high density polyethylene sheathing compounds for bridge cables using high density polyethylene resin as the main raw material, and modifiers, antioxidants, light stabilizers, carbon black or pigments as additives, processed by mixing, plasticizing and prilling. It is mainly applied to hot extrusion sheathing and spiral or sleeve of bridge cables and may also be referenced by hot extrusion sheathing and sleeve of other cable structures.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 1033.1-2008 Plastics - Methods for determining the density of non-cellular plastics - Part 1: Immersion method, liquid pyknometer method and titration method
GB/T 1040.2-2006 Plastics - Determination of tensile properties - Part 2: Test conditions for moulding and extrusion plastics
GB/T 1040.3-2006 Plastics - Determination of tensile properties - Part 3: Test conditions for films and sheets
GB/T 1043.1-2008 Plastics - Determination of charpy impact properties - Part 1: Non-instrumented impact test
GB/T 1842-2008 Plastics - Test method for environmental stress-cracking of polyethylene
GB/T 2411-2008 Plastics and ebonite - determination of indentation hardness by means of a duronmeter (shore hardness)
GB/T 3682-2000 Determination of the melt mass-flow rate (MFR) and the melt volume-flow rate (MVR) of thermoplastics
GB/T 5470-2008 Plastics - Determination of the brittleness temperature by impact
GB/T 8427-2008 Textiles - Tests for color fastness - Color fastness to artificial light: Xenon arc fading lamp test
GB/T 9341-2008 Plastics - Determination of flexural properties
GB/T 9352-2008 Plastic - Compression moulding of test specimens of thermoplastic materials
GB/T 13021 Determination for the carbon black content of polyethylene pipes and fittings by calcination and pyrolysis
GB/T 15065-2009 Black polyethylene compounds for wire and cable
GB/T 16422.3-2014 Plastics - Methods of exposure to laboratory light sources - Part 3: Fluorescent UV lamps
GB/T 17391 Test method for thermal stability of polyethylene pipes and fittings
GB/T 18251 Method for the assessment of pigment or carbon black dispersion in polyolefin pipes, fittings and compounds
RAL K7 CLASSIC Ral Color Card (Germany)
3 Product classification and specification
3.1 Classification
According to the color, there are Type H and Type C products in black and color respectively.
3.2 Specification
The products should be φ4mm×3mm cylindrical particles or particles with equivalent size.
4 Requirements
4.1 Color
The color is composed of two types, i.e. Type H and Type C, of which the former should be RAL 9005 black. According to resistance to color change, Type C should cover RAL 9003 white, RAL 7047 grey, RAL 3018 red, RAL 1018 yellow, RAL 2003 orange and RAL 5015 blue successively.
4.2 Appearance
The particles shall be uniform, smooth-faced, and free of obvious impurities and connection of 3 or more particles.
4.3 Performance
The technical performance of high density polyethylene sheathing compounds for bridge cables shall meet those specified in Table 1.
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Table 1 Technical performance of high density polyethylene sheathing
compounds for bridge cables
S.N. Item Unit Index
Type H Type C
1 Density g/cm3 0.940~0.955
2 Melt mass-flow rate g/10min ≤0.45
3 Tensile fracture stress MPa ≥25
4 Tensile yield stress MPa ≥15
3 Fracture nominal strain % ≥400
6 Modulus of elasticity for tension MPa ≥500
7 Modulus of elasticity in bending MPa <1 000
8 Notch impact strength of simply supported beam kJ/m2 ≥50
9 Shore hardness - ≥50
10 Resistance to environmental stress cracking
F0>5 000h - Passed
11 Brittleness temperature <-76℃ - Passed
12 Resistance to thermal stress cracking F0>96h - Passed
13 Oxidation induction period at 200℃ min ≥60
14 Resistance to fluorescent ultraviolet aging for 3 000h
Change rate of tensile fracture stress
Change rate of fracture nominal strain
%
%
±25
±25
15 Color fastness to light Grade - ≥7
16 Carbon black dispersion Grade ≤3 -
17 Content of carbon black % 2.5±0.3 -
5 Test methods
5.1 Color
The color shall be inspected by visual comparison with the color represented by corresponding number of RAL K7 CLASSIC in natural light.
5.2 Appearance
The appearance shall be visually inspected in natural light.
5.3 Performance
5.3.1 Specimen preparation
Specimens shall be prepared by using flash mould according to Method C given in Table 1 of GB/T 9352-2008.
Foreword i
1 Scope
2 Normative references
3 Product classification and specification
4 Requirements
5 Test methods
6 Inspection rules
7 Marking, packaging, transportation and storage
