1、BRITISH STANDARD BS2782-7: Method720B: 1979 Methods of testing Plastics Part 7: Rheological properties Method 720B: Cup flow of phenolic and alkyd moulding materials IMPORTANT NOTE. Before reading this method it is essential to read the foreword, general introduction and instructions to BS2782, issu
2、ed separately. UDC 678.5/.8:678.01:532.135BS2782-7:Method720B:1979 This British Standard, having been prepared under the directionof the Plastics StandardsCommittee, was published under the authority ofthe Executive Board and comesinto effect on 31August1979 BSI11-1999 The following BSI references r
3、elate to the work on this standard: Committee reference PLC/17 Draft for comment78/55155 DC ISBN 0 580 10903 8 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a Britis
4、h Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be
5、 indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS2782-7:Method720B:1979 BSI 11-1999 i Contents Page 0 Introduction 1 1 Scope 1 2 Reference 1 3 Principle 1 4 Apparatus 1 5 Procedure 1 6 Expression of results 2 7 Test rep
6、ort 2 Figure 1 Detail of cup flow mould 2ii blankBS2782-7:Method720B:1979 BSI 11-1999 1 0 Introduction This method which has been prepared under the direction of the Plastics Standards Committee is similar in technical content to method105B of BS2782:1970, which is being withdrawn. The method is for
7、 assessing the flow properties of phenolic and alkyd moulding materials. It is not suitable for fast-curing moulding materials. WARNING NOTE. This method does not necessarily detail all the precautions necessary to meet the requirements of the Health and Safety of Work etc Act1974. Attention should
8、be paid to any necessary safety precautions, and the method should only be operated by trained personnel. 1 Scope This method describes a procedure for assessing the flow properties of phenolic and alkyd moulding materials. 2 Reference The following standards publication is referred to in this stand
9、ard. BS593, Laboratory thermometers. 3 Principle The flow properties of moulding materials are assessed by measuring the time taken for a mould in the form of a cup of specified dimensions to close under a specified pressure and temperature. 4 Apparatus The following apparatus is required. 4.1 Stand
10、ard compression mould of form and dimensions shown in Figure 1. The mould shall comply in all respects with the details shown in thefigure. A pocket for the thermometer shall be provided in the die to reach within13mm of the outside wall of the moulding. The mould shall be made of good quality steel
11、 as usually used for moulds, e.g.high carbon, high chromium, air-hardening alloy steel, hardened to45HRC to48HRC(500HV to550HV). The surfaces marked “X” in Figure 1shall be smooth and polished. The final polishing shall be in the line of the tool draw, i.e.parallel to the direction of movement of th
12、e press. The method of heating the mould shall be such as to maintain a uniform temperature within 1 C of the specified temperature. 4.2 Compression moulding press, capable of exerting and maintaining the pressure required. The force on the mould shall be100 5kN, calculated according to the expressi
13、on appropriate to the type of press in use. In the case of an up-stroking press F = Ap mg In the case of a down-stroking press the force on the mould is given by the following expression, the symbols having the same meaning as previously. F = Ap + mg The cross-sectional area of the ram shall be dete
14、rmined from its measured diameter. The pressure gauge shall be checked for accuracy and shall be connected to the press inlet pipe. The line pressure shall not vary by more than3% during the course of the test. The inlet of the hydraulic supply shall be choked with a bored nipple so that the press r
15、am travels130mm in a period of between4s and5s when the valve is fully opened, as at the beginning of the test. 4.3 Thermometer complying with the requirements of BS593. 4.4 Timing device, graduated in divisions of0.5s or less. 5 Procedure Ensure that the mould is clean and polished. Heat the mould
16、to a temperature of163 1 C determined by inserting the thermometer in the inside end of the thermometer pocket (seefigure). Wrap the bulb of the thermometer in copper gauze or metal foil or alternatively surround it with oil to ensure that a good contact is made with the mould. Keep the mould closed
17、 until the test is started so as to maintain a uniform temperature throughout the mould. Weigh on to a charging scoop sufficient powder to give when moulding a flash of mass more than2g but less than2.5g. If a fibrous or other bulky material is being tested, lightly compress it before charging so as
18、 to form a cylinder of32mm to38mm in diameter and not more than32mm high. where F is the force on the mould (in N) A is the cross sectional area of the ram (inm 2 ) p is the gauge pressure (inPa) m is the mass of ram, platen and mould (inkg) g is the acceleration due to gravity (inm/s 2 )BS2782-7:Me
19、thod720B:1979 2 BSI 11-1999 Adjust the temperature of the powder before placing it in the mould to10 C to40 C (i.e.normal room temperature). Open the mould sufficiently to charge it with the powder; then close the mould. Ensure that the time from the beginning of the charging to closing the mould an
20、d applying full pressure is between5s and10s. Measure the time in seconds from the instant that the hydraulic gauge shows pressure (indicating that the initial pressure has been applied) to the instant that the flash ceases to move. 6 Expression of results Express the cup flow of the material as the
21、 time in seconds measured in accordance with clause5. 7 Test report The test report shall include the following particulars. a) A complete identification of the material tested, including type, source, manufacturers code numbers, previous history, etc. b) A reference to this British Standard method
22、(i.e.BS2782:Method720B) c) The result of the test. All dimensions are in millimetres. NOTEX indicates smooth and polished surfaces Figure 1 Detail of cup flow mouldblankBS2782-7: Method720B: 1979 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national
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