1、# CEN EN823 95 M 3404589 OLL2329 Y79 - _. _ - BRITISH STANDARD AEROSPACE SERIES Fibre reinforced plastics Determination of water absorption by immersion The European Standard EN 2378 : 1995 has the status of a British Standard ICs 49.040.10 UDC 678.O67-41:60.193.19:629.7 BS EN 2378 : 1995 CEN ENr237
2、8 95 I 3404589 OLL2330 190 Date BS EN 2378 : 1995 Qxt affected This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 November 1995 0 BSI 1995 The following BSI references r
3、elate to the work on this standard: Committee reference ACE164 Draft for comment 88178341 DC ISBN O 580 23111 9 Committees responsible for this British Standard The preparation of this European Standard was entrusted to Technical Committee ACE/64, Aerospace structural reinforced plastics, upon which
4、 the following bodies were represented: British Plastics Federation Ministry of Defence Society of British Aerospace Companies Limited Amendments issued since publication Amd. No. . CEN ENx2378 95 m 3404589 0332333 027 m BS EN 2378 : 1995 Contents Committees responsible National foreword page Inside
5、 front cover ii Foreword Text of EN 2378 2 3 i CEN ENx2378 95 = 3404589 OLL2332 Tb3 = BS EN 2378 : 1995 National foreword This British Standard has been prepared under the direction of the Aerospace Standards Policy Committee and is the English language version of EN 2378 : 1993 Aerospace series - F
6、ibre reinforced plastics - Determination of water absorption by immersion, published by the European Committee for Standardization (CEN). EN 2378 was produced as a result of international discussions in which the United Kingdom took an active part. Cross-references Publication referred to EN 2744 :
7、1992 Corresponding British Standard BS EN 2744 : 1992 Non-metallic material. Preferred test temperatures Compliance with a British Standard does not of itself confer immunity from legal obligations. CEN ENa2378 75 = 3YOY587 0332333 7TT I EUROPEAN STANDARD EN 2378 NORME EUROPENNE EUROPISCHE NORM Sept
8、ember 1995 ICs 49.040.10 Descriptors: aircraft industry, plastics, reinforced plastics, water absorption tests, immersion tests English version Aerospace series - Fibre reinforced plastics - Determination of water absorption by immersion Srie arospatiale - Plastiques reinforcs de fibres - Dterminati
9、on de labsorption deau par immersion Luft- und Raumfahrt - herverstrkte Kunststoffe - Bestimmung der Wasseraufnahme durch Einlagerung This European Standard was approved by GEN on 1995-09-19. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for
10、giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may beobtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official ve
11、rsions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officiai versions. CEN members are the national standards bodies of Austria, Belgium
12、, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Centrai Secretariat: rue de Stassar
13、t 36, B-1050 Brussels O 1995 Copyright reserved to CEN members Ref. No. EN 2378 : 1995 E CEN EN*2378 95 m 3404589 0332334 836 m Page 2 EN 2378 : 1995 Foreword This European Standard has been prepared by the European Association of Aerospace Manufacturers (AECMA) . After inquiries and votes carried o
14、ut in accordance with the rules of this Association, this Standard has successively received the approval of the National Associations and the Official Services of the member countries of AECMA, prior to its presentation to CEN. The European Standard shali be given the status of a national standard,
15、 either by publication of an identical text or by endorsement, at the latest by March 1996, and conflicting national standards shali be withdrawn at the latest by March 1996. According to the CENKENELEC Internal Regulations, the following countries are bound to implement this European Standard: Aust
16、ria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. CEN ENx2378 75 = 3404587 0332335 772 Page 3 EN 2378 : 1995 O Introduction The absorption of water into reinforced plastics i
17、nvolves phenomena which are characerised by the following points : - They obey diffusion laws which are still not fully understood -parameter Fick model, 4-parameter Langmuir-type model), see annex A ; - The anisotropy of the material is a variable which affects the diffusion parameters ; - The surf
18、ace finish and more generally the absorption conditions determine its behaviour ; - Determination of diffusion parameters is never simple and requires complex calculations which can only be undertaken with relatively powerful computers regardless of the mathematical model selected. For all these rea
19、sons this standard confines itself to the laying down of a simple test method for which the specimens and the procedure are defined as precisely as possible, so as to eliminate as many variables as possible. 1 Scope This standard specifies the method for the determination of water absorption by imme
20、rsion. It applies to fibre reinforced plastics in sheet form and enables : - a comparison between two materials : - the determination of diffusion parameters at a later date. The choice of these depends on the model adopted (see annex A). 2 Normative references This European Standard incorporates by
21、 dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standa
22、rd only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 2331 Aerospace series - Textile glass fibre preimpregnates - Test method for the determination of the resin and fibre content and mass of fibre per unit area
23、 EN 2564 Aerospace series - Carbon fibre laminates - Test method for the detemination of the fibre and resin fractions and porosity content EN 2744 Aerospace series - Non-metallic materials - Preferred test temperature Published as AECMA Prestandard at the date of publication of this standard CEN EN
24、812378 95 3404589 OLL2336 609 Page 4 EN 2378 : 1995 3 Principle To determine the water absorption curve with time of immersion of a sptcimen of specified shape in demineralised water at a given temperature. The absorption characteristics are obtained at right angles to the plane of the specimen. The
25、 specimen is designed so that the edge effect can be disregarded. 4 Reagents Demineralised water with a resistivity 2 3 Mnxm 5 Apparatus 5.1 Glass beakers of a sire suited to the number of specimens 5.2 accurate to f 2 C Temperature-controlled vessel capable of maintaining the beakers at the immersi
26、on temperature If necessary, provide means of water vapour recovery. 5.3 Thermometer of appropriate scale and accuracy 5.4 5.5 Air circulating oven which can be maintained at the specified temperature accurate to i 2 C Desiccator containing silica gel or equivalent 5.6 5.7 Stirrer Balance accurate t
27、o 0,l mg 6 Specimens 6.1 Determination of absorption 6.1.1 temperature and for each material. Take at least five identical specimens meeting the conditions of 6.1.5 for each immersion 6.1.2 6.1.3 Using a diamond wheel cut the specimens to the dimensions specified in figure 1 and table 1. Record the
28、particulars of the surface finish of the specimens (machining, mould release agents,.). 6.1.4 Record the orientation of the fibres or of the warp of the fabric. . All surfaces machined Unmachined surfaces Machined edges - CEN ENx2378 95 = 3404589 OLL2337 545 = Dimensions in mm a e 50 f 0,l 1 fO,O5 5
29、0. e i 0,l 1 ) a r= - Figure 1 Table 1 Page 5 EN 2378: 1995 I laminate is as near to this value as possible. 1 6.1.5 In all cases the thicknesses of specimens shall satisfy the following condition : r; 0,05 e max. -e min. e mean If this condition is not fulfilled, remove specimen with extreme thickn
30、ess values. 6.1.6 It is not permitted to drill holes in the specimens. 6.2 Determination of fibre content EN 2564 or EN 2331 according to the material on each sheet used for sampling of absorption specimens (see 6.1). 7 Procedure 7.1 Conditioning the specimens Place the specimens in the oven maintai
31、ned at (i0 f 2) C until a constant mass is obtained. To do this, check weighings shall be made at regular intervals ; these shall be reported as a drying cuwe. Record the mass Mo which represents the last weighing of the specimen to the nearest 0,l mg and then place the specimen in the desiccator. C
32、EN EN*:2378 95 3404589 0332338 481 Hours 11 2 14 18 Il61241481961168 AA I AB I AC I AD 1 AE 1 AF I AG 1 AH I AJ Weeks 2 14 16 18 Il6126(52 BA I BB I BC I BD I BE I BF I BG Page 6 EN 2378 : 1995 7.2 Immersion bath 7.2.1 Preparation Use at least 4 ml of demineralised water per square centimeter of tot
33、al specimen surface area. When the specimens are of identical composition it is possible to put several into the same beaker provided they do not touch each other. Ensure that the contact between specimens and beaker walls or specimen supports is point contact to ensure that as much as possible of t
34、he specimen is wetted. 7.2.2 Maintenance For immersions of long duration, replace the water every seven days. Analyse the bath regularly to ensure it has not been contaminated by the decomposition products from the material. If it has, the water shall be renewed and replaced more frequently. 7.3 Imm
35、ersion temperature Choose by preference (23 i 2) C or (70 i 2) C.lf other temperatures are used they shall be selected from EN 2744 with a tolerance of f 2 C. Ensure that the temperature selected is not too close to the glass transition temperature of the laminate. 7.4 Duration of immersion The tota
36、l immersion time is not specified because it depends on the material, immersion temperature, etc. The total immersion time and the times for intermediate measurements conducted during the course of immersion shall be selected according to table 2. Table 2 7.5 Immersion (for each specimen) 7.5.1 Remo
37、ve the specimen from the desiccator without finger contact. 7.5.2 completel y. Immediately place the specimen into the water at the specified temperature and immerse it Fit the cover. Place the entire apparatus in the dark, or in lighting conditions specified. Stir the bath regularly, at least once
38、a day, using the stirrer. 7.5.3 the specimen from the water. Whenever the cumulative immersion time (t) has reached one of the values listed in 7.4, remove CEN ENx2378 95 W 3404589 0332339 318 W Page 7 EN 2378: 1995 7.5.4 (23 f 2) C for 15 min. If necessary bring the specimen to ambient temperature
39、by immersing it in demineralised water at 7.5.5 Dry the specimen with filter paper or a lint-free cloth. 7.5.6 cumulative immersion time (9 at the specified temperature. Weigh immediately and record the mass M (f) to the nearest 0.1 mg. as a function of the 7.5.7 Repeal the procedure from 7.5.2 to 7
40、.5.6 as often as necessary until the end of the test. a Expression of results 8.1 water absorbed P (0 : For each cumulative immersion time (f) at the specified temperature calculate the percentage of 8.2 Plot the absorption curve (figure 2) as a function of 4 for each specimen. O 1 Figure 2 8.3 abso
41、rption at the specified temperature as a function of 4 : Plot the average absorption curve PM (9 obtained by plotting the average value of water where: pi (9 N is the percentage of water absorbed by specimen “i“ (i = 1 to N); is the total number of specimens. CEN EN*(2378 95 9 3404589 OLL2340 03T m
42、Page 8 EN 2378: 1996 8.4 Measurement of the absorption rate a This is the slope at the origin of the absorption curve P expressed as a funtion of 4 : where: *=$ 8.5 Maximum water content ME This characteristic shall only be determined if the water content reaches a stable limit within the immersion
43、time. 8.6 Further interpretations of tests Laboratories wishing to calculate the diffusion parameters may consult the bibliography, see annex A. 9 Designation EXAMPLE: Immersion temperature (see 7.3) Number of this standard Immersion time code (see 7.4) 10 Test report It shall include the following
44、: 1 O. 1 10.2 Number of this standard Full description of the material or produci tested : a) manufacturing process; b) fibre content measured: c) arrangement of the plies (if applicable). 10.3 Dimensions of each specimen 10.4 10.5 Number of specimens 10.6 Surface finish (machining, mould release ag
45、ent, .) Total conditioning time and temperature 10.7 10.8 10.9 10.1 0 10.11 10.12 10.13 10.14 CEN EN*E!378 95 3404589 0332343 T7b Page 9 EN 2378 : 1995 Drjing curve Total immersion time and temperature Lighting conditions Absorption curve for each specimen andior the mean absorption curve Absorption
46、 rate a for each specimen Maximum water content ME, if appropriate Any incident liable to have affected the results For each set of results (10.1 1 and 10.12) and each temperature (10.8): - arithmetic mean of each parameter ; - standard deviation for each parameter. CEN ENx2378 95 3404587 OLL2342 70
47、2 M Page 10 EN 2378 : 1995 Annexe A (informative) Bibliography - Hams G. Carter and alias: Langmuir-type model for anomalous moisture diffusion in composite resins, J. of Composite Materials, Vol. 12. April 1978, page 11 8 - Chi-Hung Shen and G.S. Springer: Moisture absorption and desorption of comp
48、osite materials, J. of Composite Materials, Vol. 10, January 1976, page 2 - J.N. Dewas - JNCJ: Le modle de Langmuir appliqu A la diffusion deau dans les matriaux composites type carbone-poxy, Paris 09/82 pp.89.96 CEN EN*:237B 95 3Li04589 OLL2343 849 BS EN 2378 : 1995 List of references See national
49、foreword. CEN EN*2378 95 W 3g04589 0332344 785 = BS EN 2378 : 1995 BSI 389 Chiswick High Road London W4 4AL 9511- 5- 0.4k- FP BSI - British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Contract requirements 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. Rev
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