Conservation Polymers
Code
11007
Academic unit
Faculdade de Ciências e Tecnologia
Department
Departamento de Conservação e Restauro
Credits
6.0
Teacher in charge
Joana Lia Antunes Ferreira, Maria João Seixas de Melo
Weekly hours
6
Total hours
76
Teaching language
Português
Objectives
The aim of Polymers in Conservation is to prepare the student to a critical evaluation of the importance of Polymers in Conservation, and their evolution in time, i.e., their ageing. Polymers are used as protective materials, consolidants, and as the materials from which the work of Art is made of. The student should become familiar with the literature produced in different fields of research, ranging form material science, polymer chemistry and technical art history; and aware of its importance and constant growing. The theoretical lessons may be divided in two main sections: Part 1 and Part 2, by Ana Ramos and Maria João Melo, respectively. The first part, deals with the fundamental aspects of the chemical and physical behaviour of polymeric materials and its characterization. In the second part, the fundamental aspects of polymer degradation, stability and conservation are discussed. Also, the requirements a material must fulfil to be used in conservation and restoration of cultural heritage are set and analysed.
Prerequisites
It has no application´s condition.
Subject matter
The course "Polymers in Conservation" is set in theoretical lessons (42h), laboratory experiments (30h) and exercises (4h). The theoretical lessons are given in two main sections: Part 1 and Part 2, by Ana Ramos (Assistant Professor in the Department of Chemistry) and Maria João Melo (Assistant Professor in the DCR). The experiments in the laboratory and exercise classes are given by Ana Claro (PhD student in the DCR). Maria João Melo is also the regent of the course. Evaluation is performed through i) short reports and a report, for the lab; ii) written exam, for the AT. Theoretical lessons I) Fundamental aspects of the chemical and physical behaviour of polymeric materials and its characterization. 1ª. Definition and nomenclature of macromolecules. Brief history of polymers. 2ª, 3ª. Classification of polymers concerning: synthesis and mechanisms, monomers nature in the chain, stereoisomerism, final use, processing, molecular structure, morphology and mechanical properties. 4. Identification methods. 5. Study of polymers behaviour in solution. 6ª, 7ª, 8ª. Definition of average molecular weights and its distributions; respective determination methods, absolute and not absolutes. 9ª, 10ª. Mechanical behaviour of polymeric materials (models and real behaviour). 11ª. Specific transition temperatures and its correlation with the morphology. 12ª. Crystallization mechanism. Crystalline polymers morphology: micelles and spherulitic models. 13ª. Normalization. Polymer additives. II) Fundamental aspects of polymer degradation, stability and conservation 1ª Introduction to the history of plastics degradation and conservation. 2ª Fundamental aspects of thermal and photochemical reactions; the excited state; thermal and photochemical stability. 3ª, 4ª Polymer degradation, a molecular approach: i) chemical evolution in the polymer matrix, mechanisms, kinetics and general photooxidative pathways; ii) intermediates, formation and evolution; iii) influence of internal and external factors in the degradation pathways; iv) role of anti-oxidant compounds and UV absorbers; v) The simulation methodology versus the mechanistic approach; correlating chemical changes with physical damage and loss in performance; predicting life-times. 5ª, 6ª Examples of photodegradation and photo-oxidation mechanisms in synthetic polymers: i) polyethylene, poly(vinyl acetate), polyacrylates and poly(methyl acrylates). 7ª Protective treatments: definition and general characteristics. Coatings versus materials used to consolidate. Requirements for a material to be used in Conservation and Restoration of Works of Art: the Rome Conference, 1934 (Conference on the Examination and Conservation of Works of Art), the Robert Feller classification and the current perspectives (reversibility and re-treatment). 8ª,9ª Treatments used to consolidate: i) inorganic compounds, ii) polymers such as, silicon based polymers, fluoride polymers, epoxy resins, phenol resins. 10ª, 11ª, 12ª The natural polymers and their degradation mechanisms are introduced as: 1- pictoric binders and animal glues used in Ancient Art until the end of XIX century 2- varnishes used in Ancient Art until the end of XIX century. TP lessons IR spectra interpretation Experiments and exercises Presentation of the objectives and experimental work to carry out in the laboratory 1st lesson (TP) Infrared spectroscopy: IR spectra interpretation I 2nd lesson (P) Obtaining a IR spectra of a polymer 3rd lesson (P) Obtaining IR spectra of dyes and pigments 4th lesson (TP) Infrared spectroscopy: IR spectra interpretation II 5th lesson (P) Preparation of the polymer solutions to be used in TP1 and TP2 6th lesson (P) TP1. Photodegradation study of acrylic polymers used in Conservation: PB72 e PB67. (part 1). 7th lesson (P) TP2. An ancient binding media, arabic gum: study of the influence of additives as glucose and honey on the properties of the pictorial layer 8th lesson (P) TP3. A reversible reticulation: PVA and borax TP4. Colourful experiments 9th lesson (P) TP5. Synthesis and characterization of an acrylic polymer: PMMA 10th lesson (P) Producing a vinyl emulsion 11th lesson (P) TP6. Measuring the colour coordinates (Lab*) of acrylic paints, naturally aged. Comparison and discussion of the results obtained with t0, 2000. 12th lesson (P) TP1. Photodegradation study of acrylic polymers used in Conservation: PB72 e PB67. (part 2). 13th lesson (P) Discussion of the reports.
Bibliography
I) F. W. BILLMEYER Jr., Textbook of Polymer Science, Wiley Interscience, 3ª ed. 1984; J.M.G. COWIE, Polymers: Chemistry and Physics of Modern Materials, Interte Books, 2ª Ed, 1993.; P. J. FLORY, Principles of Polymer Chemistry, Cornell Univ. Press, 10ª ed. 1978; J. BRANDRUP, E. H. IMMERGUT, Polymer Handbook, John Wiley & Sons, 4ª Ed., 1999;
II) [1] Polymers in Conservartion, ed by N. S. Allen, M. Edge and C. V. Horie, The Royal Society of Chemistry, 1992; [2] C. V. Horie, Materials for Conservation: organic consolidants, adhesives and coatings, Butterwoth-Heinemann, 5nd ed, 1995; [3] Materiali e techniche nel restauro, ed by G. G. Amoroso, Dario Flaccovio Editore, 1996; [4] Painting Conservation catalog, varnishes and surface coatings, Vol.1, American Institute for Conservation, 1996; [5] I. McNeill, in Polymers in Conservartion, p14; [7] J. F. Rabek, Polymer Photodegradation: mechanisms and experimental methods, Chapman & Hall, 1995; [7] a) C. H. J. Wells Introduction to Molecular Photochemistry, Chapman and Hall 1972; b) N. J. Turro Modern Molecular Photochemistry, University Science Books 1991; c) A. Gilbert & J. Baggott Essentials of Molecular Phtochemistry, Blackwell Scientific Publications 1991; [8] R. L. Feller., Accelerated aging – photochemical and thermal aspects, The J.Paul Getty Trust, USA, 1994; [9] J. Lemaire, J. Gardette, J. Lacoste, P. Delprat, D. Vaillant "Mechanisms of photooxidation of polyolefins: prediction of lifetime in wheathering conditions", in Polymer Durability: degradation, stabilization and lifetime predictions; ed R. L. Clough, N. C. Billingham, K. T. Gillen, American Chemical Society 1996; [10] J. L. Down, M. A. McDonald, J. Tétreault, R. S. Williams "Adhesive testing at the Canadian Conservation Institute- an evaluation of selected poly(vinyl acetate) and acrylic adhesives" Studies in Conservation 41 (1996) 19; [11] G. G. Amoroso and M. Camaiti, Scienza dei materiali e restauro, Alinea Editrice, 1997; [12] Science for Conservators vol 3, Adhesives and coatings, Routledge, 1992; [13] R. L. Feller, Standards in the evaluation of thermoplastic resins, ICOM Comittee for Conservation- 5th Triennial Meeting, 78/16/4, Zagreb 1978; [14] S. Z. Lewin, N. S. Baer "Rationale of the barium hydroxide-urea treatment of decayed stone" Studies in Conservation 19 (1974) 24-35; [15] M. A. Fox, J. K. Whitesell, Organic Chemistry, 2nd ed., Jones and Bartlett Publishers, 1997; Alkoysilanes and the consolidation of stone, George Wheeler, Getty Conservation Institute, 2005 [16] L. Masschelein-Kleiner, Ancient binding media, varnishes and adhesives, ICCROM, 1995; [17] M. Matteini and A. Moles, La chimica nel restauro: i materialli dell''''''''''''''''''''''''''''''''arte pittorica, Nardini Editore, 5nd ed, 1996; [18] G. A. van der Doelen, Molecular studies of fresh and aged triterpenoid varnishes, Ph.D. thesis-Molart, 1999.
Nota: artigos e textos vários em dossier para consulta no laboratório
Analysis of Modern Paints (Research in Conservation), Thomas J. S. Learner, Getty Conservation Institute, 2005
Teaching method
The "Polymers in Conservation" course is given through 42h of theoretical lessons, 30 h of experiments in the laboratory, 4h of exercised in Infra-red spectroscopy and 4 h for final evaluation. In average a student should dedicate 56h working time for study and 60h for the reports. During the semester the course is organized in 14 lessons of 1h30, 12 sessions in the laboratory of 3h, following a previously distributed protocol, and 2 lessons, 2h each, of IR spectra interpretation Note: with ERASMUS students or other foreign students, in the laboratory, in the discussions and in the written evaluation the following languages may be used: English, French, Italian or Spanish.