The process by which a chemical can pass through a protective film of glove material without going through pinholes, pores, or other visible openings. Individual ...
A Web Computer Tool for the Selection of Glove Material Against Chemicals Based on the « Hansen Solubility Parameters »
Daniel Drolet, Jaime Lara François Zimmerman, Alain Chollot, Gérald Perron, Robert Bourbonnais Charles M. Hansen
Portland 2011
Topics
Introduction; Theory; Testing the resistance of a material; ASTM permeation test, gravimetric cell; Solubility parameters ???; RED calculation; Development of an algorithm; Comparison data/prediction;
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Description of ProtecPo; Navigating into the tool; Operating rules and interpretation;
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The situation … Over 35 millions of chemical products with a C.A.S. number; Approximately 100 000 products are used on a daily basis in workplaces; Skin contacts are frequent and may cause irritations, allergy, burns, dermatitis, intoxications, cancer, etc.
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The situation (Cont’d) To protect themselves from dangerous products … use gloves or clothes made with materials resistant to chemicals; Most materials used for protection from chemicals are made from polymer (because of their flexibility), but...
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No polymer is resistant to all families of chemicals!
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Examples of polymeric materials used in personal protection
Latex
Multilayers Viton, Butyl, laminated
Butyl 5
Neoprene PVC
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Nitrile
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Testing the resistance ... Permeation cell (ASTM F739 ou ISO 6529); Gravimetric cell; Parameters : breakthrough time and permeation rate;
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Glove manufacturers provide information on tests for hundreds of permeation of pure products; There are databases with information on the strength of materials for a few hundred pure products;
lien Portland 2011
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How works the gravimetric cell?
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Process of permeation through a polymer material
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lien
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Permeation The process by which a chemical can pass through a protective film of glove material without going through pinholes, pores, or other visible openings. Individual molecules of the chemical enter the film and "squirm" through by passing between the molecules of the glove material. In many cases the permeated material may appear unchanged to the human eye. Absorption Diffusion Desorption/evaporation 9
Degradation A reduction in one or more physical properties of a glove material due to contact with a chemical. Certain glove materials may become hard, stiff, brittle, or they may grow softer, weaker, and swell to several times their original size. Portland 2011
Source : Ansell : http://www.ansellchemsafe.com/Content.aspx?topicID=254
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Breakthrough time and permeation rate
LIND M et al. Ann Occup Hyg 2007;51:479-485
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Permeation rate µg/cm²
© The Author 2007. Published by Oxford University Press on behalf of the British Occupational Hygiene Society
Breakthrough time min
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But… Permeation tests are not easy to do; Database information is limited, particularly for mixtures;
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We need an approach to predict the strength of materials in order to assist in the selection of the best performing materials; ProtecPo is a selection tool based on the …
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Solubility parameter, where it comes from?
δ =
ΔE V
Energy of vaporisation
Molar Volume
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The Hildebrand solubility parameter (δ) provides a numerical estimate of the degree of interaction between materials, and can be a good indication of solubility, particularly for non polar materials such as many polymers. Materials with similar values of δ are likely to be miscible.
Joel Henry Hildebrand 1881‐1983 Portland 2011
Wikipedia link 12
HSP: Tri-Dimensionnal Hansen Solubility Parameters, what is that? HSP were developed by Charles Hansen as a way of predicting if one material will dissolve in another and form a solution. Specifically, each molecule is given three Hansen parameters, each generally measured in MPa0.5: The energy from … ‐ dispersion bonds between molecules; ‐ dipolar intermolecular force between molecules; ‐ hydrogen bonds between molecules.
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These three parameters can be treated as co‐ordinates for a point in three dimensions also known as the Hansen space. The nearer two molecules are in this three dimensional space, the more likely they are to dissolve into each other. To determine if the parameters of two molecules (usually a solvent and a polymer) are within range a value called interaction radius (R0) is given to the substance being dissolved. This value determines the radius of the sphere in Hansen space and its center is the three Hansen parameters. Charles Hansen
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Source : Wikipedia
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HSP for dummies ! ... applications Hansen solubility parameters (HSP) explain … why a solvent can dissolve fingernail polish, or a sticky spruce resin, or a rubber cement. The HSP of the solvent and the HSP of the thing that is dissolved are close. If the HSP were not close, such as the case for water relative to these same materials, the “solvent” would not be good.
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There are HSP for such common things as sugar and butter, but even aspirin, phthalates, drugs, and DNA have HSP. The HSP describe whether things prefer to be near each other or not. Link Portland 2011
Video tutorial 14
Hansen approach Sum of 3 contributions
D : Dispersion bonds P : Polar forces
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δt =
δ D2 + δ P2 + δ H2
H : Hydrogene bonds
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Hansen space Homopolymer/solvents
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Obtaining data with swelling tests •HSPs polymeric material is obtained doing swelling tests with solvents having known HSP;
Nitrile material after immersion in acetone 17
•In our study, we used 40 solvents per polymeric material .
Sv = ΔV/V Solub. factor ... « good » solvent = 1 (Sv > 0,5) Solub. factor...« bad » solvent = 0 (Sv 1, RESISTANT material RED 1 Resistant Material
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Algorithm development... Glove
Swelling tests
HSP (A) and r of material 1 to n
RED (A/R)
solvents
Solvent(s)
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Known HSPs
Algorithm Y
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Comparison ! •Experimental data from literature(BT, Perm. rate, Degradation) •Experimental data Sv
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Expert jugdment
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RED (A/R)
Algorithm fine tuning
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Y
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For each polymeric material... What are the limits in terms of RED values, to set the Green, Yellow and Red zones
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RED max
Zones around the sphere
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RED min
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For each material * ... Experimental data (Sv, BT, perm. rate) expert decision R Y G
Comparison of FITs
N fits Ï false negativeÐ false positive Ð
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Empirical Determination REDmin et REDmax
Prediction from the algorithm for n Solvents décision R Y G
Nitrile Latex Butyl PVC VITON
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REDmax REDmin optimized 29
A first look! 30
Lien INRS Portland 2011
Lien IRSST 30
The entry screen ! 31
ProtecPo
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Team work 32
ProtecPo
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Conclusion … •A new tool … particularly relevant for “untested” chemicals or mixture against PM ; •Result of work of a multidisciplinary team; •Good example of a transition from fundamental research to applied research;
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•The next steps : •Coming tests with beta‐test users; •On the Web ... Fall 2011 ; •Other experimental tests (INRS) to compare the prediction and refine the algorithm if necessary; •Other PM will be added to the tool(?). Portland 2011
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The team ...
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Jaime Lara
Robert Bourbonnais Portland 2011
Charles M. Hansen 50
