1、BRITISH STANDARD AEROSPACE SERIES BS EN 2378:1995 Fibre reinforced plastics Determination of water absorption by immersion The European StandardEN2378:1995 has the status of a British Standard ICS 49.040.10 UDC 678.067-41:620.193.19:629.7BSEN2378:1995 This British Standard, having been prepared unde
2、r the directionof the Engineering SectorBoard, was published underthe authority of the Standards Board and comes intoeffect on 15 November1995 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference ACE/64 Draft for comment88/78341 DC ISBN 0 580 23111 9 Comm
3、ittees responsible for this British Standard The preparation of this European Standard was entrusted to Technical Committee ACE/64, Aerospace structural reinforced plastics, upon which the following bodies were represented: British Plastics Federation Ministry of Defence Society of British Aerospace
4、 Companies Limited Amendments issued since publication Amd. No. Date CommentsBSEN2378:1995 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN2378 3 List of references Inside back coverBSEN2378:1995 ii BSI 11-1999 National foreword This Br
5、itish Standard has been prepared under the direction of the Aerospace Standards Policy Committee and is the English language version ofEN2378:1993 Aerospace series Fibre reinforced plastics Determination of water absorption by immersion, published by the European Committee for Standardization (CEN).
6、 EN2378 was produced as a result of international discussions in which the UnitedKingdom took an active part. 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 British
7、 Standard does not of itself confer immunity from legal obligations. Cross-references Publication referred to Corresponding British Standard EN 2744:1992 BSEN2744:1992 Non-metallic material. Preferred test temperatures Summary of pages This document comprises a front cover, an inside front cover, pa
8、ges i and ii, theEN title page, pages 2 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM
9、 EN2378 September 1995 ICS49.040.10 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 defibres Dtermina
10、tion de labsorption deaupar immersion Luft- und Raumfahrt Faserverstrkte Kunststoffe Bestimmung der Wasseraufnahme durch Einlagerung This European Standard was approved by CEN on1995-09-19. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for g
11、iving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official ve
12、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 official versions. CEN members are the national standards bodies of Austria, Belgium
13、, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart
14、 36, B-1050 Brussels 1995 Copyright reserved to CEN members Ref. No. EN2378:1995 EEN2378:1995 BSI 11-1999 2 Foreword This European Standard has been prepared by the European Association of Aerospace Manufacturers (AECMA). After inquiries and votes carried out in accordance with the rules of this Ass
15、ociation, 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 shall be given the status of a national standard, either by publication of an identical text
16、 or by endorsement, at the latest by March1996, and conflicting national standards shall be withdrawn at the latest by March1996. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germ
17、any, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom. Contents Page Foreword 2 0 Introduction 3 1 Scope 3 2 Normative references 3 3 Principle 3 4 Reagents 3 5 Apparatus 3 6 Specimens 4 7 Procedure 5 8 Expression of results
18、 6 9 Designation 7 10 Test Report 7 Annex A (informative) Bibliography 8 Figure 1 4 Figure 2 6 Table 1 4 Table 2 5EN2378:1995 BSI 11-1999 3 0 Introduction The absorption of water into reinforced plastics involves phenomena which are characterised by the following points: They obey diffusion laws whi
19、ch are still not fully understood(2-parameter Fick model,4-parameter Langmuir-type model), seeAnnex A; The anisotropy of the material is a variable which affects the diffusion parameters; The surface finish and more generally the absorption conditions determine its behaviour; Determination of diffus
20、ion 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 reasons this standard confines itself to the laying down of a simple test method for which the specimens and t
21、he 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 immersion. It applies to fibre reinforced plastics in sheet form and enables: a comparison between two material
22、s; the determination of diffusion parameters at a later date. The choice of these depends on the model adopted (seeAnnex A). 2 Normative references This European Standard incorporates by dated or undated reference provisions from other publications. These normative references are cited at the approp
23、riate 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 Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publica
24、tion 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. EN 2564, Aerospace series Carbon fibre laminates Test method for the determination of the fibre and resin fractions
25、 and porosity content 1) . EN 2744, Aerospace series Non-metallic materials Preferred test temperature. 3 Principle To determine the water absorption curve with time of immersion of a specimen of specified shape in demineralised water at a given temperature. The absorption characteristics are obtain
26、ed at right angles to the plane of the specimen. The specimen is designed so that the edge effect can be disregarded. 4 Reagents Demineralised water with a resistivityU 3M7.cm 5 Apparatus 5.1 Glass beakers of a size suited to the number of specimens 5.2 Temperature-controlled vessel capable of maint
27、aining the beakers at the immersion temperature accurate to 2 C If necessary, provide means of water vapour recovery. 1) Published as AECMA Prestandard at the date of publication of this standardEN2378:1995 4 BSI 11-1999 5.3 Thermometer of appropriate scale and accuracy 5.4 Air circulating oven whic
28、h can be maintained at the specified temperature accurate to 2 C 5.5 Desiccator containing silica gel or equivalent 5.6 Balance accurate to0,1mg 5.7 Stirrer 6 Specimens 6.1 Determination of absorption 6.1.1 Take at least five identical specimens meeting the conditions of6.1.5 for each immersion temp
29、erature and for each material. 6.1.2 Using a diamond wheel cut the specimens to the dimensions specified inFigure 1 andTable 1. 6.1.3 Record the 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 fa
30、bric. Table 1 6.1.5 In all cases the thicknesses of specimens shall satisfy the following condition: If this condition is not fulfilled, remove specimen with extreme thickness values. 6.1.6 It is not permitted to drill holes in the specimens. 6.2 Determination of fibre content EN2564 orEN2331 accord
31、ing to the material on each sheet used for sampling of absorption specimens(see6.1). Figure 1 Dimensions in mm a e All surfaces machined 50 0,1 1 0,05 Unmachined surfaces Machined edges 50.e 0,1 1 a a The number of plies shall be calculated in such a way that the thickness of the laminate is as near
32、 to this value as possible. e max. e min. e mean -0,05 EN2378:1995 BSI 11-1999 5 7 Procedure 7.1 Conditioning the specimens Place the specimens in the oven maintained at(70 2) C until a constant mass is obtained. To do this, check weighings shall be made at regular intervals; these shall be reported
33、 as a drying curve. Record the mass M 0which represents the last weighing of the specimen to the nearest0,1mg and then place the specimen in the desiccator. 7.2 Immersion bath 7.2.1 Preparation Use at least4ml of demineralised water per square centimeter of total specimen surface area. When the spec
34、imens 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 the specimen is wetted. 7.2.2 Maintenanc
35、e 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 Immersion temperature Choose by preference
36、(23 2) C or(70 2) C. If other temperatures are used they shall be selected fromEN2744 with a tolerance of 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 total immersion time is not specified because it dep
37、ends 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 toTable 2. Table 2 7.5 Immersion (for each specimen) 7.5.1 Remove the specimen from the desiccator without finge
38、r contact. 7.5.2 Immediately place the specimen into the water at the specified temperature and immerse it completely. Fit the cover. Place the entire apparatus in the dark, or in lighting conditions specified. Stir the bath regularly, at least once a day, using the stirrer. 7.5.3 Whenever the cumul
39、ative immersion time (t) has reached one of the values listed in7.4, remove the specimen from the water. 7.5.4 If necessary bring the specimen to ambient temperature by immersing it in demineralised water at(23 2) C for15min. 7.5.5 Dry the specimen with filter paper or a lint-free cloth. 7.5.6 Weigh
40、 immediately and record the mass M (t) to the nearest0,1mg, as a function of the cumulative immersion time (t) at the specified temperature. 7.5.7 Repeat the procedure from7.5.2 to7.5.6 as often as necessary until the end of the test. Hours Weeks 1 2 4 8 16 24 48 96 168 2 4 6 8 16 26 52 AA AB AC AD
41、AE AF AG AH AJ BA BB BC BD BE BF BG Designation codesEN2378:1995 6 BSI 11-1999 8 Expression of results 8.1 For each cumulative immersion time (t) at the specified temperature calculate the percentage of water absorbed P (t): 8.2 Plot the absorption curve(Figure 2) as a function offor each specimen.
42、8.3 Plot the average absorption curve P M (t) obtained by plotting the average value of water absorption at the specified temperature as a function of : where: 8.4 Measurement of the absorption rate ! This is the slope at the origin of the absorption curve P expressed as a function of : where: 8.5 M
43、aximum water content M E This characteristic shall only be determined if the water content reaches a stable limit within the immersion time. 8.6 Further interpretations of tests Laboratories wishing to calculate the diffusion parameters may consult the bibliography, seeAnnex A. Figure 2 P i (t) is t
44、he percentage of water absorbed by specimen “i” (i=1 to N); N is the total number of specimens. Pt () Mt ()M 0 M 0 -100 = t t t dP d - = t =EN2378:1995 BSI 11-1999 7 9 Designation EXAMPLE: 10 Test report It shall include the following: 10.1 Number of this standard 10.2 Full description of the materi
45、al or product tested: a) manufacturing process; b) fibre content measured; c) arrangement of the plies (if applicable). 10.3 Dimensions of each specimen 10.4 Surface finish (machining, mould release agent,.) 10.5 Number of specimens 10.6 Total conditioning time and temperature 10.7 Drying curve 10.8
46、 Total immersion time and temperature 10.9 Lighting conditions 10.10 Absorption curve for each specimen and/or the mean absorption curve 10.11 Absorption rate ! for each specimen 10.12 Maximum water content M E , if appropriate 10.13 Any incident liable to have affected the results 10.14 For each se
47、t of results(10.11 and10.12) and each temperature(10.8): arithmetic mean of each parameter; standard deviation for each parameter.EN2378:1995 8 BSI 11-1999 Annex A (informative) Bibliography Harris G. Carter and alias: Langmuir-type model for anomalous moisture diffusion in composite resins, J.of Co
48、mposite Materials, Vol.12, April1978, page118 Chi-Hung Shen and G.S. Springer: Moisture absorption and desorption of composite materials, J.of Composite Materials, Vol.10, January1976, page2 J.N. Dewas JNC3: Le modle de Langmuir appliqu la diffusion deau dans les matriaux composites type carbone-pox
49、y, Paris09/82 pp.89.96BSEN2378:1995 BSI 11-1999 List of references Seenational foreword.BS EN 2378:1995 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishSta
