IAEA-TECDOC-1617 Controlling of Degradation Effects in Radiation Processing of Polymers May 2009 IAEA-TECDOC-1617 Controlling of Degradation Effects in Radiation Processing of Polymers May 2009 The originating Section of this publication in the IAEA was: Industrial Applications in Chemistry Section International Atomic Energy Agency Wagramer Strasse 5 P.O. Box 100 A-1400 Vienna, Austria CONTROLLING OF DEGRADATION EFFECTS IN RADIATION PROCESSING OF POLYMERS IAEA, VIENNA, 2009 ISBN 978–92–0–105109–7 ISSN 1011–4289 © IAEA, 2009 Printed by the IAEA in Austria May 2009 FOREWORD Since the beginning of radiation processing of polymers almost half a century ago, radiation crosslinking technologies have been extensively developed for useful commercial applications. The most well developed examples are the radiation crosslinking of wire insulation, heat shrinkable products for food packaging and electrical connections. The opposite of crosslinking namely, degradation which is used in the sense of chain scissioning here, has not been considered for long as an industrially desirable process and did not find sizeable applications. Controlled radiation degradation of polymers has now become an expanding technology encompassing the cleavage of polymer main chains, side chains or oxidative degradation. Established commercial processes based on the application of radiation degradation are now in place and a number of applications are in various stages of research, development and implementation. Radiation-induced degradation of synthetic polymers is utilized for the preparation of ion track membranes used in filtration and to prepare Teflon powder to be used in inks, lubricants and coatings. Another important application of radiation-induced degradation is in lithographic patterning. By using X rays and accelerated electrons it is possible to manufacture integrated circuits with radiation-patterned sub-micron dimensions. Natural polymers like cellulose (carboxy methyl cellulose) and other marine based polysaccharides (chitin/chitosan, alginates, carrageenans) are predominantly chain-scissioning polymers, and irradiation results in substantial decrease in molecular weight. This is accompanied with the formation of oxidation products and reduction in crystallinity. The degraded polysaccharides thus possess improved properties for applications in manufacturing of health care products, ingredients for cosmetics, plant growth promoters, viscosity modifiers in the food industry, and textile industry. The interest of Member States of the IAEA in introducing radiation technology into the polymer and plastics industry has led the IAEA to organize Coordinated Research Programmes on relevant topics. The first in this series was organized from 1994 to 1997 under the title The Stability and Stabilization of Polymers under Irradiation, with the objective of better understanding the factors affecting the stability of irradiated polymers, the main emphasis being on the enhancement of radiation-induced crosslinking. One of the main conclusions of the CRP was that much remained to be learned in terms of understanding degradation mechanism and phenomena. A consultants meeting on The Controlling of Degradation Effects in Radiation Processing of Polymers, held in 2002, provided an opportunity for extensive discussions by the experts of the subject on the recent developments and achievements of using radiation in controlled degradation of natural and synthetic polymers. The potential and use of ionizing radiation for controlled degradation of polymers have been considered from the points of view of: i) molecular weight modification, ii) bulk properties modification, and iii) surface modification. Following the recommendation of the consultants the IAEA established the CRP entitled Controlling of Degradation Effects in Radiation Processing of Polymers, covering the years 2003- 2006. This technical publication compiles the most important results and achievements of the participating centers and laboratories during the course of the said CRP. It has been prepared to give first a comprehensive summary of the findings highlighting individual contributions and the full texts of scientific reports as prepared by the respective authors of the CRP. The IAEA wishes to thank all the participants for their valuable contributions, and O. Guven for the technical editing of this IAEA-TECDOC. The IAEA officer responsible for this publication was M.H. de Oliveira Sampa of the Division of Physical and Chemical Sciences. EDITORIAL NOTE The papers in these proceedings are reproduced as submitted by the authors and have not undergone rigorous editorial review by the IAEA. The views expressed do not necessarily reflect those of the IAEA, the governments of the nominating Member States or the nominating organizations. The use of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the IAEA. The authors are responsible for having obtained the necessary permission for the IAEA to reproduce, translate or use material from sources already protected by copyrights. CONTENTS SUMMARY ..........................................................................................................................................1 Effects of ionizing radiation on commercial food packaging .............................................................13 E.A.B. Moura, A.V. Ortiz, H. Wiebeck, A.B.A. Paula, A.O. Camargo, L.G.A. Silva Application of positron annihilation (PA) methods, together with conventional ones, to study the structural changes in some environmentally friendly polymers upon ionising radiation................................................................................................................41 M.A. Misheva Analysis of plasma treated metallized polymers and conventional polymers modified by various techniques ..................................................................................................55 A. Macková Controlling of degradation effects in radiation processing of polymers .............................................67 E.A. Hegazy, H. Abdel-Rehim, D.A. Diaa, A. El-Barbary Effect of radiation on ultra high molecular weight polyethylene (UHMWPE)...................................85 Sungsik Kim, Young Chang Nho Modification of microstructures and physical properties of ultra high molecular weight polyethylene by electron beam irradiation..................................................................................95 Y.C. Nho, S.M. Lee, H.H. Song Electrospinning of polycaprolactone and its degradation effect by radiation ...................................107 Y.C. Nho, J.-P. Jeun, Y.-M. Lim Mitigation of degradation by different class of antioxidants in LDPE exposed to ionizing radiations.................................................................................................................117 T. Yasin, S. Ahmed, Z.I. Zafar Influence of radiation on some physico-chemical properties of gum acacia.....................................125 T. Yasin, S. Ahmed Radiation resistance of polypropylene modified by amine stabilizers versus PP copolymers..........129 Z. Zimek, G. Przybytniak, A. Rafalski, E. Kornacka Improvement in the thermal performance of polypropylene.............................................................139 T. Zaharescu Effect of irradiation on polyolefin-based materials: 1. Polymorphism in conventional isotactic polypropylend by effect of gamma radiation .............................................................................................153 M.L. Cerrada, E. Pérez, C. Álvarez, A. Bello, R. Benavente, J.M. Pereña Effect of irradiation on polyolefin-based materials: 2. Effect of irradiation in metallocene polymeric materials: amorphous ethylene-norbonene copolymers and crystalline syndiotactic polypropylene ................................................................................................157 M.L. Cerrada, E. Pérez, A. Bello, R. Benavente, J.M. Pereña Effect of irradiation on polyolefin-based materials: 3. Effect of electron irradiation in the crystallization rate of composites of syndiotactic polypropylene with clay nanoparticles...............................165 M.L. Cerrada, V. Rodríguez-Amor, E. Pérez, The use of radiation-induced degradation in: I. Controlled degradation of isoprene-isobutene rubber; II. Controlling molecular weights of polysaccharides; III. Controlling the conductivity of polyaniline blends via in-situ dehydrochlorination of PVC ....................................................................................171 O. Güven Insights into oxidation mechanisms in gamma irradiated polypropylene, utilizing selective isotopic labelling with analysis by GC/MS, NMR and FTIR ....................................189 R. Bernstein, S.M. Thornberg, R.A. Assink, D.M. Mowery, M.K. Alam, A.N. Irwin, J.M. Hochrein, D.K. Derzon, S.B. Klamo, R.L. Clough Application of chitin/chitosan in agriculture.....................................................................................205 Truong Thi Hanh, Nguyen Quoc Hien, Tran Tich Canh Application of chitin/chitosan in environment..................................................................................213