6 Adhesion Testing 6.1 Fundamentals of Adhesion...6-1 6.2 Standardization of Adhesion Tests...6-3 6.3 Delamination Procedures ...6-4 6.4 Local Debonding Systems...6-7 6.5 Flaw Detection
Trang 26 Adhesion Testing
6.1 Fundamentals of Adhesion 6-1
6.2 Standardization of Adhesion Tests 6-3 6.3 Delamination Procedures 6-4 6.4 Local Debonding Systems 6-7 6.5 Flaw Detection Methods 6-10
6.6 Outlook 6-12 References 6-13
6.1 Fundamentals of Adhesion
Without sufficient adhesion, a coating of otherwise excellent properties in terms of resistance to weather, chemicals, scratches, or impact would be rather worthless It is therefore necessary to provide for good adhesion features when paint materials are formulated There must also be adequate means for controlling the level of adhesion strength after the coating has been spread and cured on the substrate Moreover, methods should be available that allow for the detection of any failure in the case of the dissolution of the bond between coating and substrate, under any circumstances whatsoever
6.1.1 Components at the Interface
In chemical terms, there is a considerable similarity between paints on one side and adhesives or glues
in this chapter to concentrate on the behavior of paint materials Adhesion is the property requested in either case, though perhaps with different emphasis on its intensity, according to the intended use Such a coating is, in essence, a polymer consisting of more or less cross-linked macromolecules and
a certain amount of pigments and fillers Metals, woods, plastics, paper, leather, concrete, or masonry,
to name only the most important materials, can form the substrate for the coating
It is important, however, to keep in mind that these substrate materials may inhibit a rigidity higher than that of the coating Under such conditions, fracture will occur within the coating, if the system experiences external force of sufficient intensity Cohesive failure will be the consequence, however, if the adhesion at the interface surpasses the cohesion of the paint layer Otherwise, adhesive failure is obtained, indicating a definite separation between coating and substrate
Ulrich Zorll
Forschungsinstitut für Pigmente and Lacke
DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM
Components at the Interface • Causes of Failure • Measures of
Cross-Cut Test • Tensile Methods Adhesion
Scratch Technique • Indentation Debonding • Impact Tests
Ultrasonic Pulse-Echo System • Acoustic Emission Analysis •
Knife-Cutting Method • Peel Test • Blister Method
Thermographic Detection of Defects
on the other (Figure 6.1) Both materials appear in the form of organic coatings; thus, it is appropriate
Trang 37 Coating Calculations
7.1 Introduction 7-1 7.2 Resins 7-1 7.3 Pigments 7-2 7.4 Solvents 7-2 7.5 Additives 7-2 7.6
7.7 Calculations 7-2
7.8 Converting to a 100 Gallon Formulation 7-4 7.9 Cost 7-4 7.10 Coverage 7-5 7.11 Computer Use 7-5 Bibliography 7-5
7.1 Introduction
Coatings are defined as mixtures of various materials The questions arise as to how much of which materials, and how do these things relate The materials fall into four general categories, as follows:
• Resins
• Pigments
• Solvents
• Additives
7.2 Resins
These are the generally solid, sticky materials that hold the system together They are also called binders, and when in a solvent, they are the vehicles for the system They may come as a “single-package” or “two-package” system Single package is just the liquid resin or the resin in solvent Two package means that
an “A” part was blended with a “B” part to cause a chemical reaction In both systems, we need to know the amount of solid resin present This dry material divided by the total of the dry plus the solvent is frequently called a “resin solid.” With the two-package systems, we need to know not only the solids but also the ratio of these solids to form the desired film This ratio may be designated as a simple ratio of
1 to 1 Or it may be based on 1 or 100, as 0.3 to 1, or 30 parts per hundred, or a total of 100 as 43 to
57 These ratios determine the film properties We will also need to know the density (weight per unit volume, usually as pounds per gallon) of the resin or vehicle to help calculate volume
Arthur A Tracton
Consultant
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Formulation Weight • Formulation Volume • Formulation Density • Formulation of “Nonvolatile by Weight” •
Ratio (Weight) • Pigment Volume Content (Volume)
Conventions 7-2
Formulation “Nonvolatile by Volume” • Pigment to Binder
Trang 4Coating Calculations
No.
Material lb/gal gal/lb %NV Cost, $/lb Weight Volume Dry Weight Dry Volume #/100 gal gal/100 gal Cost/gal
7
8
9
10
Factor = 1.96
On Total Formulation
© 2006 by Taylor & Francis Group, LLC
Trang 5% Solvent
% Water
Cost,
$/lb Weight Gallons Dry Wt Dry Vol #/100 gal gal/100#
Cost/
100 gal Water Solvent
1 Gloss Varnish 8.43 0.118623962 1 0 0 $0.00 75 8.896797153 75.00 8.896797153 347.76 41.25 $0.00 0 0
2 Resin @ 40% in BCarbAc 8.71 0.114810563 0.4 0.6 0 $0.00 25 2.870264064 10.00 1.148105626 115.92 13.31 $0.00 0 69.55284525
3 Titanium Dioxide 10.5 0.095238095 1 0 0 $0.00 95 9.047619048 95.00 9.047619048 440.50 41.95 $0.00 0 0
5 Butyl Carbitol Acetate 10.8 0.092592593 0 1 0 $0.00 7.4 0.685185185 0.00 0 34.31 3.18 $0.00 0 34.31273699
6 Cobalt Drier, 6% 17.83 0.05608525 0.5 0.5 0 $0.00 0.253 0.014189568 0.13 0.007094784 1.17 0.07 $0.00 0 0.586562328
7 Lead Drier, 12% 8.5 0.117647059 0.5 0.5 0 $0.00 0.379 0.044588235 0.19 0.022294118 1.76 0.21 $0.00 0 0.878684278
vol pigment + binder
© 2006 by Taylor & Francis Group, LLC
Trang 68 Infrared Spectroscopy
of Coatings
8.1 Introduction 8-1 8.2 Principles 8-1 8.3
8.4 Data Collection 8-3
8.5 Data Interpretation 8-5 8.6 Applications 8-6 References 8-7
8.1 Introduction
Infrared (IR) spectroscopy is a most useful technique for characterizing coatings, a very cost-effective and efficient means of gathering information If not the final answer, IR studies can point the way to other information or techniques needed to solve a problem Ease of sample preparation is one advantage
of IR There are numerous ways of presenting the coating sample to the infrared spectrometer The wide variety of sampling accessories or attachments, which can easily be swapped in and out of most spec-trometers, enables the study of liquids and solids under a wide range of conditions There is large body
of literature on infrared methodology,1,2,3 and there are extensive collections of reference spectra available Almost all components of coatings can be identified by IR; it is especially useful for polymers IR spectroscopy can monitor changes, such as drying, curing, and degradation, which occur to coatings Quality control of raw materials and process monitoring during coating synthesis and formulation can
be done by IR spectroscopy
Most important to the identification of coatings and the study of their properties is the skill of the analytical scientist This factor is often overlooked because the trend in analytical instrumentation in recent years has been increasing computer control and automation Even when these systems are at hand, they have little value without a well-trained and experienced analytical scientist behind them The individual with a coatings problem or application is well advised to seek the services of an experienced spectroscopist
8.2 Principles
The atoms of any molecule are continuously vibrating and rotating The frequencies of these molecular motions are of the same order of magnitude (1013 to 1014 cycles per second) as those of IR radiation When the frequency of molecular motion is the same as that of the IR radiation impinging on that
Douglas S Kendall
National Enforcement Investigations Center, U.S
Environmental Protection Agency
DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM
Infrared Microscopy • Imaging
Separation • Transmission Spectra • Attenuated Total
Depth Profiling • Other Sampling Methods
Instrumentation 8-2
Reflectance (ATR) • Infrared Photoacoustic Spectroscopy and
Trang 78-8 Coatings Technology Handbook, Third Edition
38 D Lin-Vien, N B Colthup, W G Fateley, and J G Grasselli, The Handbook of Infrared and Raman
Characteristic Frequencies of Organic Molecules New York: Academic Press, 1991.
39 B J Kip, T Berghmans, P Palmen, A van der Pol, M Huys, H Hartwig, M Scheepers, and D
Wienke, Vib Spectrosc., 24, 75 (2000).
40 J R Ferraro and K Krishnan, Eds., Practical Fourier Transform Infrared Spectroscopy: Industrial
and Laboratory Chemical Analysis New York: Academic Press, 1989.
41 B Schrader and D Bougeard, Eds., Infrared and Raman Spectroscopy: Methods and Applications.
Weinheim, Germany: VCH Publishers, 1995
42 W Sueteka and J T Yates, Surface Infrared and Raman Spectroscopy: Methods and Applications.
New York: Plenum Press, 1995
43 A M Millon and J M Julian, in ASTM Spec Tech Publ., Anal Paints Relat Mater., STP 1119, 173
(1992)
44 J K Haken and P I Iddamalgoda, Prog Org Coat., 19, 193 (1991).
45 S V Compton, J R Powell, and D A C Compton, Prog Org Coat., 21, 297 (1993).
46 R L De Rosa and R A Condrate, Glass Researcher, 9, 8 (1999).
47 A R Cassista and P M L Sandercock, J Can Soc Forensic Sci., 27, 209 (1994).
48 J A Payne, L F Francis, and A V McCormick, J Appl Polym Sci., 66, 1267 (1997).
49 G A George, G A Cash, and L Rintoul, Polym Int., 41, 162 (1996).
50 J L Gerlock, C A Smith, E M Nunez, V A Cooper, P Liscombe, D R Cummings, and T G
Dusibiber, Adv Chem Ser., 249, 335 (1996).
51 A A Dias, H Hartwig, and J F G A Jansen, Surf Coat Int., 83, 382 (2000).
52 R J Dick, K J Heater, V D McGinniss, W F McDonald, and R E Russell, J Coat Technol., 66,
23 (1994)
53 M W Urban, C L Allison, G L Johnson, and F Di Stefano, Appl Spectrosc., 53, 1520 (1999).
54 D J Skrovanek, J Coat Technol., 61, 31 (1989).
55 M L Mittleman, D Johnson, and C A Wilke, Trends Polym Sci., 2, 391 (1994).
56 M Irigoyen, P Bartolomeo, F X Perrin, E Aragon, and J L Vernet, Polym Degradation and
Stability, 74, 59 (2001).
57 H Kim and M W Urban, Polymeric Mater Sci and Eng., 82, 404 (2000).
58 B W Johnson and R McIntyre, Prog Org Coat., 27, 95 (1996).
59 M R Adams, K Ha, J Marchesi, J Yang, and A Garton, Adv Chem Ser., 236, 33 (1993).
60 L J Fina, Appl Spectrosc Rev, 29, 309 (1994).
61 T Buffeteau, B Besbat, and D Eyquem, Vib Spectrosc., 11, 29 (1996).
62 N Dupuy, L Duponchel, B Amram, J P Huvenne, and P Legrand, J Chemom, 8, 333 (1994).
63 M W C Wahls, E Kentta, and J C Leyte, Appl Spectrosc., 43, 214 (2000).
64 J E Dietz, B J Elliott, and N A Peppas, Macromolecules, 28, 5163 (1995).
65 T A Thorstenson, J B Huang, M W Urban, and K Haubennestal, Prog Org Coat., 24, 341 (1994).
66 B W Ludwig and M W Urban, J Coat Technol., 68, 93 (1996).
67 E Kientz and Y Holl, Polym Mater Sci Eng., 71, 152 (1994).
68 G C Pandey and A Kumar, Polym Test., 14, 309 (1995).
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Trang 89 Thermal Analysis
for Coatings Characterizations
9.1 Introduction 9-1 9.2 Characteristics 9-1 9.3 Techniques 9-1 9.4 Applications 9-2 Bibliography 9-3
9.1 Introduction
The evaluation of substances and finished materials by thermal analysis will be discussed as a tool that the paint chemist can use to help evaluate coating properties These properties are those that change as
a function of temperature
9.2 Characteristics
Substances change in a characteristic manner as they are heated Thermal analysis (TA) monitors these changes TA procedures are generally used to characterize various substances and materials that change chemically or physically as they are heated These changes in properties as a function of temperature have been used to help characterize the interrelationship of a coating’s composition and performance
TA methods or techniques measure changes in properties of materials as they are heated or at times cooled
A TA evaluation entails subjecting a small sample of from a few milligrams to 100 mg to a programmed change in temperature The resulting change in property is detected, attenuated, plotted, and measured
by a recording device
The instrumentation consists of an analysis module, a heating or cooling source, a measuring device, and a system for reporting the results, usually as an X–Y plot A computer is used to program and control the procedure and analyze and store the results
9.3 Techniques
The techniques of prime importance in coatings’ characterization and analysis include differential scan-ning calorimetry (DSC), differential thermal analysis (DTA), thermogravimetric analysis (TGA), ther-momechanical analysis (TMA), and dynamic mechanical analysis (DMA) Each of these will be discussed, with examples of the information derivable from each procedure
William S Gilman
Gilman & Associates
DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM