Historic Textile and Paper Materials II. Conservation and Characterization 9780841216839, 9780841212664, 0-8412-1683-5

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ACS SYMPOSIUM SERIES 410

Historic Textile and Paper Materials II Conservation and Characterization

S. Haig University of California—Davis

Howard L. Needles, EDITOR University of California—Davis

Developed from a symposium sponsored by the Cellulose, Paper, and Textile Division at the 196th National Meeting of the American Chemical Society, Los Angeles, California, September 25-30, 1988

American Chemical Society, Washington, DC 1989

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

Library of Congress Cataloging-in-Publication Data Historic textile and paper materials II: conservation and characterization S. Haig Zeronian, editor, Howard L. Needles, editor p.

cm.—(ACS Symposium Series, 0097-6156; 410)

"Developed from a symposium sponsored by the Cellulose, Paper, and Textile Division at the 196th National Meeting of the American Chemical Society Lo Angeles California, September 25-30, Includes bibliographical references ISBN 0-8412-1683-5 1. Textile fabrics—Conservation and restoration— Congresses. 2. Paper—Preservation—Congresses. I. Zeronian, S. Haig, 1932. II. Needles, Howard L. III. American Chemical Society. Cellulose, Paper, and Textile Division. IV. American Chemical Society. Meeting (196th: 1988: Los Angeles, Calif.). V. Series TS1449.H57 746—dc20

1989 89-38410

CIP

The paper used in this publication meets the minimum requirements of American National Standard for Information Sciences—Permanence of Paper for Printed Library Materials, ANSI Z39.48-1984. _ Copyright © 1989 American Chemical Society All Rights Reserved. The appearance of the code at the bottom of the first pace of each chapter in this volume indicates the copyright owner's consent that reprograpnic copies of the chapter may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per-copy fee through the Copyright Clearance Center, Inc., 27 Congress Street, Salem, MA 01970, for copying beyond that permitted by Sections 107 or 108 oT the U.S. Copyright Law. This consent does not extend to copying or transmission by any means—graphic or electronic—for any other purpose, such as for general distribution, for advertising or promotional purposes, Tor creating a new collective work, for resale, or for information storage and retrieval systems. The copying fee for each chapter is indicated in the code at the bottom of the first page of the chapter. The citation of trade names and/or names of manufacturers in this publication is not to be construed as an endorsement or as approval by ACS of the commercial products or services referenced herein; nor should the mere reference herein to any drawing, specification, chemical process, or other data be regarded as a license or as a conveyance oT anyrightor permission to the holder, reader, or any other person or corporation, to manufacture, reproduce, use, or sell any patented invention or copyrighted work that may in any way be related there to. Registered names, trademarks, etc., used in this publication, even without specific indication thereof, are not to be considered unprotected by law. PRINTED IN THE UNITED STATES OF AMERICA

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

ACS Symposium Series M . Joan Comstock, Series Editor

1989 ACS Books Advisory Board Paul S. Anderson Merck Sharp & Dohme Research Laboratories

Mary A. Kaiser

E. I. du Pont de Nemours and Company

Alexis T. Bell University of California—Berkeley

Harvey W. Blanch University of California—Berkeley

Malcolm H. Chisholm Indiana University

John L. Massingill

Dow Chemical Company

Daniel M. Quinn

University of Iowa

James C. Randall Alan Elzerman

Exxon Chemical Company

Clemson University

Elsa Reichmanis John W. Finley

Nabisco Brands, Inc.

Natalie Foster

Lehigh University

Marye Anne Fox The University of Texas—Austin

AT&T Bell Laboratories

C. M. Roland U.S. Naval Research Laboratory

Stephen A. Szabo Conoco Inc.

Wendy A. Warr

Imperial Chemical Industries

G. Wayne Ivie

U.S. Department of Agriculture, Agricultural Research Service

Robert A. Weiss

University of Connecticut

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

Foreword The ACS SYMPOSIUM SERIES was founded in 1974 to provide a

medium for publishing symposia quickly in book form. The format of the Series parallels that of the continuing ADVANCES IN CHEMISTRY SERIES except that, in order to save time, the papers are not typeset but are reproduced as they are submitted by the authors in camera-readyform.Papers are reviewed under the supervision of the Editors with the assistance of the Series Advisory Board and are selected to maintain the integrity of the symposia; however verbatim reproductions of previously pub lished papers are no research are acceptable, because symposia may embrace both types of presentation.

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

Preface

EXTENSIVE

RESEARCH HAS BEEN PUBLISHED on the

chemistry and

physics of paper and textiles. From the volume of available work, physical scientists must extract the information required by conservators to assist them in the preservation offibrousmaterials. To this end, the Cellulose, Paper, and Textile Division of the American Chemical Society has sponsored four symposi paper and textiles of histori provided a forum where conservators and physical scientists could meet and discuss matters of mutual interest Papers presented at the first three meetings have been published as chapters in three volumes of the Advances in Chemistry Series: • Preservation of Paper and Textiles of Historic and Artistic Vabie\ Williams, John C., Ed.; Advances in Chemistry 164; American Chemical Society: Washington, DC, 1977. • Preservation of Paper and Textiles of Historic and Artistic Value II; Williams, John C., Ed.; Advances in Chemistry 193; American Chemical Society: Washington, DC, 1981. • Historic Textile and Paper Materials: Conservation and Characterization; Needles, Howard L.; Zeronian, S. Haig, Eds.; Advances in Chemistry 212; American Chemical Society: Washington, DC, 1986. This volume contains chaptersfromthe fourth symposium. The seriousness of problems related to the conservation of paper is already well recognized. In about 1850, paper became much more susceptible to deterioration because of the acidic nature of the products prepared by the manufacturing processes then being introduced. Today, steps are being taken to correct and prevent problems. The Wall Street Journal of March 6, 1989, reported that the publishing industry estimated

vii In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

that in 1990, 50% of all paper used in book publishing would be acid free compared with only 25% in 1989. According to a report in the March 13, 1989, Chemical & Engineering News, acid-free paper is estimated to last 300 years compared with an approximately 30-year lifetime for acidic paper. The change to alkaline—neutral papermaking is laudable and will assist in the preservation of books published in the future. (The production of alkaline-neutral paper is surveyed in Chapter 1 of this volume.) However, the difficulty with books printed since 1850 remains. Methods of deatidifying paper are critically evaluated in Chapter 2, and the potential of graft copolymerization as a means of strengthening paper is described in Chapter 3. Another problem conservators face is the deterioration of paper by exposure to light; it is discussed in Chapter 4 Paper is hydrophilic and may turn yellow over time atmosphere in which books are stored is brought out in Chapter 5, and yellowing is discussed in Chapter 6. Unlike paper, textiles are made from a wide range offibersformed from different types of polymers. Textiles are usually colored, and the type of dye used depends on the fiber. Thus, each fiber has its own unique set of problems. For example, syntheticfibersare less susceptible to insects than are naturalfibers,whose potential for damage depends on thefiberand on the insect. Also, the rate at whichfibersdeteriorate when exposed to sunlight varies, depending on how they have been dyed and which type of dye has been used. Again, afiber'ssusceptibility to a reagent depends on its organochemical nature. Different dyes are susceptible to different reagents as well. Thus, whereas some general rules can be applied to textile conservation, knowledge of the individual fiber, dye, andfinishis important Currently, the vast majority of textiles being collected by museums are madefromnaturalfibers,and attention is focused on these products in this volume. Silk is discussed in Chapters 7-9, and cellulosics in Chapters 10 and 11. Techniques that may be useful for the characterization of textiles to be preserved are described in Chapters 13-15. One of the fascinations of studying textiles is that in addition to being manufactured from conventionalfibers,they can be formed from other materials. Problems related to conservation of a particularly sensitive material, tapa cloth, are discussed in Chapter 12. The authors wish to thank Sandy Brito for her valuable and prompt assistance with respect to the correspondence generated in the

viii In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

organization of the symposium and of this volume. We would also like to acknowledge the help we received from Cheryl Shanks and Donna Lucas of the ACS Books Department in the preparation of this book.

S. HAIG ZERONIAN

University of California Davis, CA 95616 HOWARD L. NEEDLES

University of California Davis, CA 95616 August 3, 1989

ix In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

Chapter 1

Permanence and Alkaline—Neutral Papermaking D. J. Priest Department of Paper Science, University of Manchester Institute of Science and Technology, Manchester, P.O. Box 88, Sackville Street, Manchester M60 1QD, United Kingdom

The papermaking proces i increasingl bein modified that the sheet i s forme environment, rathe Pape this way i s normally longer lasting because acid hydrolysis of the cellulose can no longer occur. However, the reasons for introducing the modified process are largely economic, and the product may not necessarily meet specifications for permanence and durability. This review describes the technicalities of the economic advantages (including easier fibre refining, increased filler content, the use of calcium carbonate fillers, and the availability of cost-efficient neutral sizes), the factors involved i n making a change to neutral/alkaline papermaking, and how all this impinges on producing a satisfactory permanent paper. Paper i s e s s e n t i a l l y a bonded mat or f e l t of r e l a t i v e l y small f i b r e s to which can be added, i f required, f i l l e r s , wet strengtheners, coatings and so on. Although a paper-like material can be produced from many d i f f e r e n t polymeric f i b r e s , paper i t s e l f i s nearly always made using f i b r e s from natural sources, usually, but not exclusively of course, from wood. These natural f i b r e s a l l comprise polysaccharides of one sort or another, predominantly c e l l u l o s e , which are very hydrophilic because they contain many accessible hydroxyl groups. The e s s e n t i a l adhesion between f i b r e s i s a consequence o f hydrogen bonds formed through these hydroxyl groups, as i s the s e n s i t i v i t y o f unmodified paper to d i s i n t e g r a t i o n when wetted by water. In many of i t s uses, paper needs to have resistance to penetration by aqueous f l u i d s such as w r i t i n g inks or the damping solutions used i n lithographic p r i n t i n g . The treatment given to the surfaces of f i b r e s to make them hydrophobic, which i s usually done as the sheet i s being formed, pressed and dried on the papermaking machine, i s known as " i n t e r n a l s i z i n g " , to d i s t i n g u i s h i t from "surface s i z e " applied on a s i z e press part way down the drying section of the machine. 0097-6156/89A)410-0002$06.00A) o 1989 American Chemical Society

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

1.

PRIEST

Alkaline-Neutral Papermaking

3

Since the early days of machine made paper i n the f i r s t h a l f of the nineteenth century, the most widely applied method of i n t e r n a l s i z i n g has been the use of n a t u r a l l y occurring resinous materials ("rosins") i n conjunction with an aluminium s a l t , usually aluminium sulphate (called "alum" by papermakers). Various forms of r o s i n sizes (rosin soaps, r o s i n emulsions, f o r t i f i e d rosins) have been developed over the years to improve the process, but these variants s t i l l involve the use of alum as a means of ensuring that f i b r e s r e t a i n a layer of size. Aluminium sulphate hydrolyses i n aqueous solution to y i e l d complex hydrated aluminium ions plus hydroxonium ions (Jj 2), and hence a low pH. Papers made using alum/rosin s i z i n g are often said to be " a c i d i c " , although t h i s i s rather imprecise terminology. A complete d e f i n i t i o n , following the related TAPPI standard method (3), i s that paper a c i d i t y i s the extent to which water-soluble materials i n the paper a l t e r the hydrogen-hydroxyl ion equilibrium of pure water causing an excess of hydroge under s p e c i f i e d conditions The important point i s that the c e l l u l o s e i n these alum/rosin sized papers i s susceptible to acid h y d r o l y s i s , which r e s u l t s i n a lowering of the degree of polymerisation and, eventually, to a serious reduction i n the strength of f i b r e s and to complete embrittlement of the paper. Some recent work i n the w r i t e r ' s laboratory suggests that when alum/rosin papers are made, the hydroxonium ions which lead to the degradation are adsorbed independently of aluminium i o n i c species W. In recent years, increasing attention i s being paid by the paper industry to systems i n which s i z i n g i s accomplished without the need to have the wet end of the machine running at a c i d i c pH values. In these newer systems the pH may be around the neutral point, or be s l i g h t l y a l k a l i n e due usually to the use of calcium carbonate f i l l e r (see below), so they are known as " n e u t r a l / a l k a l i n e " . Papers made i n t h i s way do not y i e l d a c i d i c aqueous extracts and hence degrade more slowly (5, 6). C l e a r l y , t h i s i s of great s i g n i f i c a n c e to those concerned with ensuring that important books and a r c h i v a l documents use paper expected to have a long l i f e , and which w i l l not lead i n 30-150 years time to the enormous problems now being experienced i n l i b r a r i e s and archives with paper made 30-150 years ago (7). However, i t must be recognised that the reasons f o r introducing neutral/alkaline papermaking were not p r i m a r i l y associated with permanence; papers made i n t h i s way do not necessarily meet a l l the requirements f o r permanence and d u r a b i l i t y . Also, the alum/rosin a c i d i c s i z i n g method has been such a dominant force i n papermaking that many other features of the process have been designed around i t and adapted to i t ; the often used term "alum/rosin s i z i n g system" i s e n t i r e l y appropriate. Making the change to n e u t r a l / a l k a l i n e papermaking nearly always involves, as we s h a l l see, much more than throwing a switch or opening a valve. In a previous publication i n t h i s series (8), Hagemeyer set a l k a l i n e papermaking i n the context of future demand f o r paper, and dealt b r i e f l y with some of the technical consequences. Since then, more m i l l s have converted to the new method, and the aim of t h i s chapter i s to inform the reader i n some d e t a i l about the reasons f o r changing to n e u t r a l / a l k a l i n e papermaking, some of the consequences f o r the production and properties of paper, and how the change impinges on

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

4

HISTORIC TEXTILE AND PAPER MATERIALS U

permanence and d u r a b i l i t y . I t i s important for those concerned with conservation and permanence to be able to communicate with papermakers and others with an awareness of relevant problems. Where possible, l i t e r a t u r e i s c i t e d , but a complete review i s not intended, and some of the comments a r i s e from the w r i t e r ' s past involvement i n some of the i n d u s t r i a l aspects of n e u t r a l / a l k a l i n e papermaking. REASONS FOR CHANGING TO NEUTRAL/ALKALINE PAPERMAKING. As i n most i n d u s t r i a l change, the c h i e f Incentive i s economic, and we need to look at ways i n which the n e u t r a l / a l k a l i n e process gives r i s e to savings i n the cost of production. Four main areas are involved: the f i b r e f u r n i s h , mineral f i l l e r s , the s i z i n g system and the papermaking process i t s e l f . Although f o r convenience these w i l l be discussed i n turn, i t should be noted at the outset that there i s a great deal of i n t e r a c t i o n between the various aspects. FIBRE FURNISH. I t i s w e l or r e f i n e d at a neutral process i s greater than at the a c i d i c pH of around 4.5 common i n alum/rosin systems. (When running an alum/rosin system i t i s i n e v i t a b l e that much of the stock preparation part of the m i l l operates at low pH because most of the water used i s recycled from the wet-end of the paper machine). The increase i n r e f i n i n g e f f i c i e n c y means, f o r example, that a given l e v e l of strength i n the paper can be obtained f o r a lower expenditure of energy. This i s a major fundamental economic incentive for converting to n e u t r a l / a l k a l i n e papermaking, because large amounts of expensive energy are consued i n r e f i n i n g f i b r e s (_10)* This basic advantage can be exploited i n d i f f e r e n t ways, depending on the p a r t i c u l a r product being made and market requirements (£)• For example: a) The composition of the f i b r e f u r n i s h can be a l t e r e d . The proportion of hardwood pulp might be increased, f o r instance, to give a product with the same strength as before, but with improved formation and opacity. Some cheap, r e l a t i v e l y weak, bleached mechanical pulp might be introduced, or the proportion already used increased, again g i v i n g better uniformity and opacity, and a lower apparent density, but without l o s s of strength. This l a t t e r trend, of course, would not be acceptable i n a permanent grade of paper. b) The p o t e n t i a l l y improved strength can be o f f s e t by increasing the amount of mineral f i l l e r i n the paper, and t h i s i s a common route to f o l l o w , because f i l l e r s are usually much l e s s expensive than the fibrous raw materials they replace, w h i l s t at the same time properties such as brightness and opacity are improved. This important aspect i s discussed more f u l l y i n the next s e c t i o n . c) A product of s i m i l a r composition can be made but simply using l e s s energy i n r e f i n i n g . In f a c t , these three approaches are not mutually exclusive, and a m i l l would need to consider how to combine changes to optimise f i n a n c i a l savings w h i l s t producing a paper acceptable i n q u a l i t y to the p a r t i c u l a r market being served.

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

1.

Alkaline-Neutral Papermaking

PRIEST

5

FILLERS. In addition to being able to use more f i l l e r , a very important feature of running n e u t r a l / a l k a l i n e i s the c a p a b i l i t y of greatly increasing the choice of mineral f i l l e r . This i s because i t becomes e a s i l y possible to use f i l l e r s constituted from calcium carbonate (CaCO-), of which there are many d i f f e r e n t types. In alum/rosin systems, the pH i s low enough f o r chemical reaction with the CaCO~ to occur, producing troublesome evolution of C0 gas, causing f r o t n and foaming and a l t e r i n g the i o n i c c o n s t i t u t i o n and pH of the wet-end c i r c u i t s . 2

CaC0 + 2H0**" — ^ 3

3

Ca

2 +

+ C0

2

+

3^0

Some attempts have been made i n the past to overcome t h i s d i f f i c u l t y by pre-treating the s l u r r y of carbonate f i l l e r with s p e c i a l starches or water soluble polymers i n order to protect the f i l l e r p a r t i c l e s from a c i d attack f o r long enough to avoid foaming e t c i f the treated carbonate s l u r r i n the acid environment can work w e l l i f properly set up and c o n t r o l l e d , they have not found wide a p p l i c a t i o n , l a r g e l y being superseded by the advent of cost e f f e c t i v e neutral s i z e s , which also avoids the cost of the protecting starch or polymers. However, a p a r a l l e l development i s the a v a i l a b i l i t y of r o s i n s i z e emulsions which are e f f e c t i v e at higher pH's ( i . e . just on the acid s i d e ) , and at least one m i l l i n the UK has been taking t h i s approach to using low additions of alum with carbonate f i l l e r (J2). Once again, the advantage of being able to use carbonate f i l l e r s can be r e a l i s e d i n many d i f f e r e n t ways, depending both on the product and market requirements, and also on the a v a i l a b i l i t y and cost of f i l l e r supplies. Calcium carbonate f i l l e r s are produced either by controlled comminution of n a t u r a l l y occurring materials d i f f e r i n g as widely as chalk, limestone or even marble, or by a chemical process leading to "Precipitated Calcium Carbonates", or PCC»s. Within each type there are a range of products, varying i n p a r t i c l e s i z e and d i s t r i b u t i o n , p a r t i c l e shape, and brightness. D i f f e r e n t materials are produced at d i f f e r e n t locations throughout the world, so a f f e c t i n g detailed l o c a l economics. In Europe, there i s a p l e n t i f u l supply of inexpensive ground chalk f i l l e r , and there i s u s u a l l y an incentive to replace some or a l l of the clay (used i n an acid s i z i n g system) with chalk, and to increase the t o t a l f i l l e r content. However, due regard must be paid to relevant properties of the paper; e.g. large proportions of chalk f i l l e r w i l l increase the o i l a b s o r p t i v i t y of the paper and hence i t s behaviour i n p r i n t i n g processes. Also, although the more e f f i c i e n t a l k a l i n e beating w i l l generally allow r e t e n t i o n of strength at higher f i l l e r l e v e l s , the r e l a t i v e values of d i f f e r e n t types of strength can change, leading to possible d i f f i c u l t i e s i n use. For example, i f burst and t e n s i l e strength remain unaltered, but the paper i s not as s t i f f as before, there i s a danger that sheets w i l l not feed properly i n t o p r i n t i n g machines. In the USA, where there i s not the same supply of cheap ground chalks, i t may be cost e f f e c t i v e to use the more expensive precipitated carbonate, e s p e c i a l l y i f i t can be prepared i n the m i l l , as i s often the case. Through proper c o n t r o l , i t i s possible to make f i n e p a r t i c l e sized uniform products of high brightness, g i v i n g the p o s s i b i l i t y of

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

6

HISTORIC TEXTILE AND PAPER MATERIALS II

replacement, at l e a s t i n part, of very expensive s p e c i a l i t y f i l t e r s such as titanium dioxide (.1^3) • Use of PCC can sometimes also be j u s t i f i e d , even where supplies of cheap chalk are a v a i l a b l e , when making products i n v o l v i n g the use of T10 * In complete contrast, the choice might be a lower brightness coarser f i l l e r where the main aim i s cheapening a product without much a f f e c t i n g i t s o p t i c a l properties, i . e . employing carbonate only as a filler. Using appropriate techniques, and f o r suitable products, i t i s now possible to make s a t i s f a c t o r y papers containing 25-30J w/w of chalk f i l l e r , although 15-20* i n general n e u t r a l / a l k a l i n e p r i n t i n g and w r i t i n g grades i s probably more common. Such high l e v e l s of f i l l e r are not needed f o r supplying an " a l k a l i n e reserve" i n permanent grades of paper; the American National Standard f o r permanence of paper f o r printed l i b r a r y materials proposes a minimum of 2% as calcium carbonate Although the presence of excess f i l l e r i s u n l i k e l y to be detrimental to permanence properties of the pape d u r a b i l i t y - such as those s p e c i f i e d i n the standard. 2

SIZING. C l e a r l y , the key to the increased use of n e u t r a l / a l k a l i n e systems i s the a v a i l a b i l i t y of suitable c o s t - e f f i c i e n t s i z e s . This has come about through the development of synthetic materials which are designed to form chemical covalent bonds with the hydroxyl groups i n the surfaces of f i b r e s (13> 15). In addition to the reactant group, the s i z e molecule also has a hydrophobic portion, usually consisting of short a l k y l chains. The two types of s i z e i n most common use are a l k y l ketene dimers (AKD) or a l k y l succinic anhydrides (ASA); Figure 1 shows the intended s i z i n g reactions. In practice several problems have had to be overcome before t h i s apparently a t t r a c t i v e method of s i z i n g could be implemented efficiently. Since the ketene or the anhydride have to react with hydroxyl groups, they w i l l also react r e a d i l y with water; i . e . the molecules are hydrolysed to give non-reacting carboxylic acids (Figure 2). Some means must therefore be found to permit addition of the s i z e s to the wet-end of a paper machine, and then to ensure that they are retained within the wet paper web i n such a way that an adequate s i z e f i l m i s deposited on f i b r e s i n the dried sheet. This i s made more awkward by the e s s e n t i a l l y hydrophobic nature of the molecules. The means adopted i s to prepare emulsions of the s i z e s , often using c a t i o n i c starch as a s t a b i l i s e r and retention a i d . The storage s t a b i l i t y of these reactive synthetic s i z e emulsions i s also of p r a c t i c a l importance; AKD sizes tend to be delivered by the manufacturer i n emulsion form, w h i l s t ASA i s emulsified on s i t e s h o r t l y before pumping i t i n t o the wet-end. This i s an area where much c o n f i d e n t i a l manufacturer's expertise comes into play. At one time, d i f f i c u l t i e s were encountered with ensuring that the desired degree of s i z i n g developed i n a reasonable time, e s p e c i a l l y with AKD's. With rosin/alum, s i z i n g i s complete i n the r e e l at the end of the paper machine, but with some early AKD s i z e s , water resistance continued to develop f o r some days a f t e r the paper was made, making q u a l i t y control d i f f i c u l t i f not impossible. With newer grades of AKD t h i s problem no longer a r i s e s , provided care i s taken to ensure that temperatures i n the drying section of the paper machine are high enough

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

1. PRIEST

Alkaline-Neutral Papermaking

(a) Cril-OH+^-CH

1

R

2

I I

—

CeH-0-CO-CHR Hg OINH + 7KI + 2H 0 2

2

2

A 50 mg sample of each ground f a b r i c was introduced into a 50 mL Erlenmeyer flask, and 20-30 mL of d e i o n i z e d / d i s t i l l e d water was added. After approximately 15 minutes, each solution was f i l t e r e d through ashless f i l t e r paper into a 100 mL volumetric f l a s k . A 2 mL aliquot of Nessler's Reagent (APHA, Fisher S c i e n t i f i c Company) was

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

7.

Screening of Stabilizers

BECKER ET

101

added to the 100 mL s o l u t i o n . After at least 10 minutes, but not longer than 20 minutes, the absorbance of the solution at 425 nm was measured on a Bausch and Lomb Spectronic 20 spectrophotometer. Results and Discussion Although the treated samples were heated for up to four days i n increments of one day and exposed to l i g h t for up to 20 days i n 2-day i n t e r v a l s , not a l l the degraded fabrics were evaluated. The heatdegraded samples i n Set A were measured after two and four days exposure while those i n Set Β were measured after d a i l y exposure. The l i g h t degraded samples i n Set A were measured after four-day exposure i n t e r v a l s and those i n Set Β were measured either after 2day i n t e r v a l s (tensile strength and color) or 4-day i n t e r v a l s (ammonia and amino-group content). Since the results observed and conclusions reached on properties measured during intermittent exposures are s i m i l a r to those based on the complete 4-day heating and 20-day l i g h t exposures exposures w i l l be reporte the remaining data are available elsewhere ( 4 ) · Strength Loss. The strengths of the a r t i f i c i a l l y aged samples are reported i n Table V. After 20-day l i g h t exposure, the only sample i n Table V.

Yarn Tensile Strength Retained After A r t i f i c i a l Aging of Fabrics i n Sets A and B. (Four Days at 150°C or 20 Days of Light Exposure) SET A

SET Β

DMF

Heat m 37.9

Light (%) 14,.8

Stabilizer None

Heat m 31.4

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rwfwrs ta aatar af laapaj r

Fraaaat ia atjatftaaat aaiiaatf ( > 3 0 « af akawats af ataaria aa. >11). Praaaat. (aj.ahSOfi af akawats af ataaria aa. >1t) Aaaaat (aat aVtaataaO. Pasrtaaj arasaat («J. 9S ar toss af alaawats af ataaria aa. >11).

In Historic Textile and Paper Materials II; Zeronian, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.

HISTORIC TEXTILE AND PAPER MATERIALS Π

Table I I I . pH, S u l f u r , Ash of H i s t o r i c Flags tapi»

pH»

Mfw/* « f

c

A*fc i

BUKMrtPta 012 019 022 02ft 096 137 173 066 167 168 089 098 002 108

4J61 4.97 9.10 430 4J06 4J64 4.17 33 4.1 4J00 4JB1 930 4JB9 939

0371 0.27 0.19 036 030 OJB 032

9.99 6.49 732 4.75 3J62 C=0 absorption peak a t about 1700 cm"*. The exact composi­ t i o n of the extract i s not known. Note, however, that (1) the ex­ t r a c t absorbs a t about 265 nm i n the UV, i n d i c a t i n g carbonyl species; (2) the extract absorbs a t about 1700 cm" i n the IR, i n d i c a t i n g e i t h e r carbonyl or carboxyl species; and (3) that the extract i s acidic. I t i s l i k e l y , then, that t h i s peak may be assigned t o various low-molecular-weight degradation products that may account for the a c i d i t y o f the extract. I t also should be noted that t h i s spectrum i s e s s e n t i a l l y the same as that reported by K l e i n e r t (18, 19) f o r the aqueous extract of n a t u r a l l y and a r t i f i c i a l l y aged l i n e n . 1

Kinetics The change i n absorbance a t the maximum i n the 255 - 270 nm region o f f i l m s baked f o r various periods o f time a t 140, 110 and 90 °C are shown i n Figure 7. A l l o f the data were f i t t o curves of the form of Equation 5. The reaction rate r e s u l t s are summarized i n Table I f o r both the early (up t o twenty hours) and the l a t t e r portions of the curves (beyond twenty hours). This range o f temperatures, 90 - 140 °C, was chosen because i t includes the b o i l i n g point of water. Since f i l m s baked a t tempera­ tures above 100 °C have a much lower moisture content than those baked a t