1、BRITISH STANDARD BS2782-8: Method835D: 1980 Methods of testing Plastics Part8: Other properties Method835D: Determination of gelation time of thermosetting resins using a hot plate IMPORTANT NOTE. Before reading this method it is essential to read the foreword, general introduction and instructions
2、to BS2782, issued separately. UDC 678.5/.8:678.01:536.421.4:678.072BS2782-8:Method 835D:1980 This British Standard, having been prepared under the directionof the Plastics StandardsCommittee, was published under the authority ofthe Executive Board andcomesinto effect on 30May1980 BSI11-1999 The foll
3、owing BSI references relate to the work on this standard: Committee reference PLC/17 Draft for comment79/51003 DC ISBN 0 580 11312 4 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. Co
4、mpliance with a British 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 to3 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorp
5、orated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS2782-8:Method 835D:1980 BSI 11-1999 i Contents Page 0 Introduction 1 1 Scope 1 2 References 1 3 Principle 1 4 Apparatus 1 5 Test temperature 2 6 Proce
6、dure 2 7 Expression of results 2 8 Test report 3ii blankBS2782-8:Method 835D:1980 BSI 11-1999 1 0 Introduction This method has been prepared under the direction of the Plastics Standards Committee. It is one of a series of methods for determination of gelation time of resins, the others being as fol
7、lows: It should be noted that BS4584 “Metal-clad base materials for printed circuits” Part11 “Bonding sheet material for use in the fabrication of multilayer printed boards: EP-GC-11” also includes a method for testing resins used for laminates, etc. This method describes a procedure for determining
8、 the time for a phenolic resin, in solid or liquid form or in solution, to set to a rubbery state when maintained at one specified elevated temperature. It is suitable for comparative testing of heat hardening phenolic resins of the resol type or mixtures of novolak phenolic resins with hexamine. It
9、 can also be applied to some thermosetting resins or solutions other than phenolic (e.g.epoxide resins with hardeners) where appropriate. It provides a rapid method for quality control and a measure of the suitability of the resin, mixture, or solution for use in moulding compositions, laminating pr
10、ocesses, surface coating and other bonding applications. WARNING NOTE. This method does not necessarily detail all precautions necessary to meet the requirements of the Health and Safety at Work etc. Act1974. Attention should be paid to any appropriate safety precautions, and the method should be op
11、erated only by trained personnel. 1 Scope This method describes a procedure for the determination of gelation time at a specified temperature of heat hardening phenolic or other thermosetting resins. 2 References The following standards publications are referred to in this method. BS593, Laboratory
12、thermometers. BS700, Graduated pipettes (including blowout pipettes). BS1704, General purpose thermometers. 3 Principle A sample of the resin (solid, liquid or solution) is placed on the surface of a horizontal steel hot plate at the specified temperature. The molten mass is worked with a palette kn
13、ife in a controlled manner until gelation is detected. The time to achieve gelation is recorded. The specified temperature is chosen so that the gelation time does not exceed300s. 4 Apparatus The following apparatus is required. 4.1 Gelation hot plate (gel plate) which may be either steam heated or
14、electrically heated as described in4.1.1 or4.1.2 respectively. Other closely similar designs may be used provided that it can be shown that they give similar results. 4.1.1 Steam cored gel plate, consisting of a steel rectangular plate cored for steam heating which is set with the surface horizontal
15、 within a framework of rigid heat insulating materials and the whole surrounded on three sides by a draught shield. The steel plate shall be45mm thick and have surface dimensions of240mm 190mm. The plate shall be drilled horizontally with a6.5mm diameter thermometer socket with the axis of this sock
16、et6.35mm below the upper surface. The plate is conveniently set up with a longer side to the front, the draught shield fitted at the back and two sides, and with the thermometer socket drilled in the centre of the right hand side. A50mm 50mm square shall be engraved or etched in outline at the centr
17、e of the surface of the plate. Suitable controls for steam supply shall be provided to enable the plate to operate consistently at the specified temperature 0.5 C as measured by a thermometer(4.2) fitted in the drilled socket. 4.1.2 Electrically heated gel plate, consisting of a square steel plate25
18、mm thick with surface dimensions of150mm 150mm. Beneath this plate shall be clamped a cast aluminium heating block of the same dimensions as the plate, i.e.150mm 150mm 25mm. The plate and heating block shall be set horizontally within a framework of rigid heat insulating material and the whole surro
19、unded on three sides by a draught shield. Method835A Determination of gelation time of phenolic resins Method835B Determination of gelation time of polyester resins (manual method) Method835C Determination of gelation time of polyester and epoxide resins using a gel timer Method835E Determination of
20、 gelation time of resins in impregnated materials used for laminatesBS2782-8:Method 835D:1980 2 BSI 11-1999 The plate shall be drilled horizontally with a6.5mm diameter thermometer socket with the axis of the socket6.35mm below the upper surface. The plate is conveniently set up with the draught shi
21、eld at the back and at both sides and with the thermometer socket drilled in the right hand side at a point15mm from the centre of the side. A50mm 50mm square shall be engraved or etched in outline at the centre of the surface of the plate. The aluminium heating block shall consist of a400W metal-sh
22、eathed mineral-insulated tubular electrical heater, arranged in a configuration so as to provide even heating over the area around which is cast aluminium to make the block. A suitable socket to receive a thermostat probe shall be drilled in the aluminium block. Suitable thermostat controls shall be
23、 provided to enable the gel plate to operate consistently at the specified temperature 0.5 C as measured by a thermometer(4.2) fitted in the drilled thermometer socket. 4.2 Thermometer complying with the requirements of BS593 designation F255C/100 (range95 C to255 C) or BS1704, general purpose with
24、a range0 C to250 C. The thermometer chosen shall be a close fit in the socket of the plate. 4.3 Palette knife, with blade preferably125mm long 22mm broad or, if not available,150mm long 25mm broad. 4.4 Graduated pipette,5ml capacity, complying with the requirements of BS700, with the tip cut off to
25、provide a rapid delivery. 4.5 Analytical balance 4.6 Paint scraper with nominal40mm wide blade. 4.7 Stopwatch or stopclock 4.8 Pestle and mortar 4.9 Beeswax 5 Test temperature The test temperature shall be as specified in the relevant product specification. 6 Procedure 6.1 Preparation of sample. In
26、the case of solid resins grind a representative sample to powder in the pestle and mortar. When specified for novolak resins, mix the required proportional mass of powdered hexamine thoroughly with the ground sample. Test in the as-received condition pre-ground resins and resin/hexamine mixtures, li
27、quid resins and resin solutions except where it is specified that hardener additions are required. 6.2 Determination of gelation time. Adjust the temperature of the gel plate to that specified in the material specification. Weigh to the nearest0.05g,1g of the powdered solid resin or mixture, or pipe
28、tte the volume of liquid resin or resin solution containing1g (calculated from the known resin content of the sample) using the pipette and transfer rapidly to the centre of the50mm square on the surface of the gel plate (1 0.05g of very viscous liquid resins may be weighed directly on the tip of th
29、e palette knife). Start the stopwatch or stopclock simultaneously. Immediately spread the resin over the50mm square with sweeping movements of the palette knife and work the melted resin over the square with a slow side to side movement of the knife which is alternated with a gentle patting and pull
30、ing towards the operator. Repeat the following cycle at the rate of one stroke per second: two side-to-side smoothing strokes followed by six patting strokes toward the operator. Keep the knife well down on the resin. Do not raise it at any time more than13mm above the plate and maintain the resin e
31、venly spread but within the50mm square as far as possible. As soon as the resin starts to become more viscous, test frequently for stringing by lifting the palette knife not more than25mm above the plate at intervals not greater than3s. When the melted resin sticks to the entire length of the wet pa
32、rt of the palette knife in hair-like strings, this is designated the “string point” and the time at which this occurs is required on some occasions. After the resin has reached the “string point” continue with the patting motion but apply the smoothing only when it is necessary to secure an even dis
33、tribution of resin over the50mm square. Continue the patting strokes until the resin no longer strings but is rubbery and when this occurs observe or stop the stopwatch. Note the time from the start of the whole operation. Clean the plate by scraping the resin off the plate with the paint scraper; b
34、eeswax may be applied to soften the resin. Finally wipe clean. Make a second determination using a fresh portion of the material. 7 Expression of results Calculate the mean of the two results and report this mean as the gelation time expressed in seconds.BS2782-8:Method 835D:1980 BSI 11-1999 3 8 Tes
35、t report The test report shall include the following particulars. a) Complete identification of the material tested, including type, source, manufacturers code number and previous history. b) A reference to this British Standard method, i.e.BS2782:Method835D:1980. c) The test temperature. d) The res
36、ult of the test and, if required, the individual results. e) The time to the “string point”, if required.BS2782-8: Method835D: 1980 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the
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