Reinforcing Degraded Textiles: Effect of Deacidification on Fabric

25 Reinforcing Degraded Textiles: Effect of Deacidification 1

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on Fabric Deterioration

N. KERR, S. P. HERSH, P. A. TUCKER, and G. M. BERRY School of Textiles, North Carolina State University, Raleigh, NC 27650

Textiles which have deteriorated with age are frequently weak, brittle and powdery and often require treatment to prevent further damage. However, there is a lack of understanding of both the mechanisms of degradation and techniques for preserving historic textiles. For these reasons studies were initiated about three years ago to examine new approaches to textile conservation. Part of this program involved the characterization of naturally degraded historic textiles and the development of model degraded fabrics by means of artificial aging (1) and the use of textile finishing resins as consolidants (2). The naturally degraded archaeological fabrics examined were obtained from two locations in Peru. The first group of samples dated from about 1200 A.D. and came from a Chancay Valley grave site. The others dated from about 1000 B.C. and were obtained from the Gramalote site in northern Peru. The model degraded fabrics were prepared from a contemporary cotton print cloth by irradiation with high voltage electrons, exposure to dry heat and hydrolysis with mineral acids. The fabrics were characterized by measuring their tensile and tear strengths, extent of oxidation via Turnbull's blue test and infrared spectroscopy, infrared crystallinity index and molecular weight. A comparison of the properties of the artificially degraded fabrics with those of the Pre-Columbian cottons indicated that none of the artificially degraded fabrics duplicated the ancient samples in all properties. For example, none of the aging techniques produced the severe powdering evident in naturally degraded samples. The strength levels of laboratory degraded samples, however, could be controlled to match those of the archaeological cottons. Both types of samples, whatever the degradation process, showed a sharp drop in DP and an lr

Project supported by the National Museum Act, vrtiich is administered by the Smithsonian Institution. 0-8412-0485-3/79/47-095-357$05.00/0 ©

1979 A m e r i c a n C h e m i c a l Society

Eby; Durability of Macromolecular Materials ACS Symposium Series; American Chemical Society: Washington, DC, 1979.

DURABILITY O F MACROMOLECULAR

358

MATERIALS

accompanying s t r e n g t h l o s s . However, t h e degree o f c r y s t a l l i n i t y , a c t u a l DP a n d e x t e n t o f o x i d a t i o n d e p e n d e d o n t h e mode o f d e g r a d a t i o n . The r e s e a r c h t o be r e p o r t e d h e r e c o n c e r n s e f f o r t s t o p r e v e n t o r r e t a r d degradation o f c o t t o n t e x t i l e s by a p p l y i n g v a r i o u s deacidifying agents. Prevention of

Deterioration

T h e d e t e r i o r a t i o n o f p a p e r i n books and documents h a s been a c o n c e r n f o r many y e a r s . Research by paper conservators i n d i c a t e s t h a t b o o k s and m a n u s c r i p t s may b e p r o t e c t e d f r o m a g i n g by treatment w i t h a l k a l i n e agents which n e u t r a l i z e the a c i d i t y o f the paper as i t develops ( 3 A , S , 6 , J ) . The d e a c i d i f i c a t i o n process not o n l y n e u t r a l i z e s the a c i d i t y o f the o x i d i z e d c e l l u l o s e , b u t a l s o l e a v e s an " a l k a l i n e r e s e r v e " i n the paper t o retard future deterioration. T e x t i l e s made f r o m c e l l u l o s e f i b e r s s u c h a s c o t t o n , f l a x and r a y o n a r e s u b j e c t t o t e n d e r i n g w i t h a g e j u s t a s p a p e r weakens a n d y e l l o w s w i t h a g e . A s a c o n s e r v a t i o n m e a s u r e , t e x t i l e s may b e washed and r i n s e d t h o r o u g h l y t o remove o x i d a t i o n b y p r o d u c t s and n e u t r a l i z e the f a b r i c . Yet historic textiles are rarely t r e a t e d w i t h a l k a l i n e a g e n t s t o n e u t r a l i z e them and r e d u c e t h e rate of degradation. T h e r e i s a r e l u c t a n c e among c o n s e r v a t o r s t o l e a v e o n a f a b r i c a n y s u b s t a n c e w h i c h was n o t o r i g i n a l l y p r e s e n t i n the f a b r i c . H o w e v e r , i f a f a b r i c i s l i k e l y t o become a c i d i c from o x i d a t i o n o r exposure t o atmospheric p o l l u t a n t s , t h e p r e s e n c e o f a n a l k a l i n e b u f f e r w o u l d be e x p e c t e d t o r e d u c e f u t u r e tendering o f the f a b r i c . T h e r e m i g h t b e some h i s t o r i c t e x t i l e s which would b e n e f i t from the p r e s e n c e o f an a l k a l i n e r e s e r v e , p r o v i d e d t h e b u f f e r h a d no d e l e t e r i o u s e f f e c t o n t h e p h y s i c a l p r o p e r t i e s o f the t e x t i l e . I f a f a b r i c c o u l d n o t be n e u t r a l i z e d by wet c l e a n i n g , a v a p o r phase t r e a t m e n t might s e r v e t o remove t h e a c i d i t y o f t h e t e x t i l e . T h e o b j e c t i v e o f t h e p r e s e n t s t u d y was t o d e t e r m i n e w h e t h e r c o t t o n f a b r i c s t r e a t e d w i t h a l k a l i n e a g e n t s c a n be p r o t e c t e d from d e g r a d a t i o n during a c c e l e r a t e d oven a g i n g . The b u f f e r s s e l e c t e d were ones which have been used i n p a p e r c o n s e r v a t i o n . M o r p h o l i n e was o f p a r t i c u l a r i n t e r e s t b e c a u s e i t c a n be a p p l i e d from the vapor phase. Experimental Fabric. T h e f a b r i c u s e d for t h e a c c e l e r a t e d a g i n g t e s t s was a 78 x 76 c o u n t 3 . 5 o z / y d u n b l e a c h e d s c o u r e d p r i n t c l o t h . B e f o r e u s e , i t was m a c h i n e washed t w i c e , o n c e i n T r i t o n ® X - 1 0 0 n o n i o n i c d e t e r g e n t and o n c e i n h o t w a t e r . 2

Reagents. agents,

Cotton

Ca(0H)2,

fabrics

were t r e a t e d w i t h t h r e e

MgCe>3 a n d m o r p h o l i n e ,

alkaline

before


25.

KERR E T A L .

Fabric

Deterioration

359

a r t i f i c i a l l y aging i n an o v e n . S o l u t i o n s o f Ca(0H)2 and MgCX>3 p r e p a r e d f o r wet t r e a t i n g t h e c o t t o n by s h a k i n g o n e gram o f r e a g e n t i n 500 m l d i s t i l l e d w a t e r f o r two m i n u t e s . T h e m i x t u r e was t h e n a l l o w e d t o s e t t l e f o r 24 h o u r s b e f o r e d e c a n t i n g the c l e a r supernatant l i q u i d . T h e c o t t o n was e x p o s e d t o m o r p h o l i n e v a p o r f r o m a s o l u t i o n p r e p a r e d b y c o m b i n i n g 50 m l m o r p h o l i n e w i t h 50 m l d i s t i l l e d w a t e r . w

e

r

e

Application Procedures. A l l f a b r i c s a m p l e s were c u t t o 4 x 6 i n c h (W x F ) r e c t a n g l e s . T h r e e r e p l i c a t e s p e c i m e n s were p r o c e s s e d f o r e a c h t r e a t m e n t t o be s u b j e c t e d t o e a c h o f t h e a r t i f i c i a l aging experiments d e s c r i b e d below. For the c o m p a r i s o n s a m p l e s w h i c h were n o t t o be* a r t i f i c i a l l y a g e d , s i x r e p l i c a t e s p e c i m e n s were t r e a t e d e i t h e r w i t h w a t e r o r o n e o f the a l k a l i n e agents. T h e c o n t r o l f a b r i c was w e t o u t f o r 10 m i n u t e s w i t h d i s t i l l e d w a t e r a t 2 4 ° C , d r a i n e d f o r 10 s e c o n d s , t h e n d r i e d f l a t o n g l a s s . T o t r e a t s a m p l e s w i t h M3CO3 a n d C a ( O H ) 2 , t h e s a m p l e s w e r e immersed i n t h e s o l u t i o n a t 24 °C f o r 10 m i n u t e s ( l i q u o r t o f a b r i c r a t i o o f . 5 0 : 1 ) , d r a i n e d 10 s e c o n d s t h e n l a i d f l a t o n g l a s s t o d r y . Ca(OH)2 t r e a t m e n t g a v e a w e i g h t g a i n o f a p p r o x i m a t e l y 2%. F o r t h e 360 and 600 h o u r a g i n g e x p e r i m e n t s , t h e s a m p l e s t o be t r e a t e d w i t h M3CO3 w e r e i m m e r s e d , d r i e d and t h e n immersed and d r i e d a s e c o n d t i m e t o o b t a i n a n a d d - o n o f a p p r o x i m a t e l y 2%. S a m p l e s were e x p o s e d t o m o r p h o l i n e v a p o r b y h a n g i n g f o r 1 h o u r a t 2 4 °C f r o m a r a c k i n a d e s i c c a t o r c o n t a i n i n g 100 m l o f t h e a q u e o u s m o r p h o l i n e s o l u t i o n . A p a r t i a l vacuum was drawn t o e n c o u r a g e t h e p e n e t r a t i o n o f morpholine vapor i n t o the c o t t o n f a b r i c . Other conditions f o r e x p o s i n g t o m o r p h o l i n e were i n v e s t i g a t e d . A r t i f i c i a l Aging. S a m p l e s were a r t i f i c i a l l y a g e d b y e x p o s u r e e i t h e r t o d r y o r n o i s t h e a t i n an o v e n . A l l except the 600 h o u r e x p o s u r e s were c o n d u c t e d i n a F i s h e r I s o temp f o r c e d d r a f t oven. T h e 600 h o u r e x p o s u r e was c a r r i e d o u t i n a G r i e v e I n d u s t r i a l forced d r a f t o v e n . D r y a g i n g was a c c o m p l i s h e d b y h a n g i n g s a m p l e s i n t h e o v e n and h e a t i n g a t 100°C o r 170°C f o r 5 0 , 1 1 6 , 120 o r 600 h o u r s . A r e l a t i v e humidity o f approximately 50% was a c h i e v e d b y p l a c i n g t h e s a m p l e s i n d e s i c c a t o r s c o n t a i n i n g s u f f i c i e n t water t o h a l f s a t u r a t e the atmosphere w i t h i n the c o n t a i n e r . An e a r l i e r a t t e m p t t o o b t a i n a c l o s e d s y s t e m w i t h a r e l a t i v e h u m i d i t y o f 50% u s i n g a s a t u r a t e d s o l u t i o n o f N a l was n o t s u c c e s s f u l . A saturated solution of Nal s h o u l d m a i n t a i n a r e l a t i v e h u m i d i t y o f 50.4% a t 100°C i n a c l o s e d c o n t a i n e r (8). VJhen a d e s i c c a t o r c o n t a i n i n g 145 m l o f s a t u r a t e d N a l s o l u t i o n was h e a t e d i n t h e o v e n a t 1 0 0 ° C , t h e c o l o r l e s s s o l u t i o n g r a d u a l l y t u r n e d d a r k brown a s i o d i n e was released. I n a d d i t i o n , a l a y e r o f c r y s t a l s formed o n t h e s u r f a c e o f the s a l t s o l u t i o n thus preventing the evaporation o f w a t e r and c o n t r o l o f r e l a t i v e h u m i d i t y .


DURABILITY

360 To o b t a i n a r e l a t i v e

humidity o f

w a t e r was a d d e d t o e a c h d e s i c c a t o r . approximately within glass the

the rod

in

times

was p l a c e d

360 and 600

in

saturate

treated

a partial

100°C,

atmosphere a

then

Samples were h e a t e d

Fabric Tensile

Strength:

a t 21 + 2 ° C a n d 65 + 2% r e l a t i v e

ASTM m e t h o d D-1628 test)

the

vacuum was d r a w n ,

the o v e n .

of

w a t e r was

s a m p l e s was hung o n

Samples

for

(Breaking

load

were

humidity.

s t r e n g t h was m e a s u r e d o n an I n s t r o n CRE m a c h i n e grab

10 m l

quantity of

hours.

T e s t Methods. conditioned

100% a t This

t h a t needed t o

Each s e t o f

the d e s i c c a t o r ,

container

120,

three

container.

O F MACROMOLECULAR MATERIALS

Tensile

according

and e l o n g a t i o n o f

to

textiles

-

(9).

F a b r i c pH: H i e pH o f o n e o r two s a m p l e s f r o m e a c h t r e a t m e n t a n d a g i n g p e r i o d was m e a s u r e d u s i n g t h e f o l l o w i n g a d a p t a t i o n o f t h e B a r r o w m e t h o d (6): t e n s q u a r e i n c h e s o f f a b r i c ( 0 . 9 g ) was c u t i n t o 1/8 i n c h s q u a r e s , a d d e d t o 50 m l w a t e r a t 4 7 ° C a n d s t i r r e d v i g o r o u s l y to f a c i l i t a t e w e t t i n g out o f the f a b r i c . A f t e r s t e e p i n g f o r o n e h o u r a t room t e m p e r a t u r e , t h e f a b r i c was r e m o v e d , a n d t h e pH o f t h e l i q u i d was m e a s u r e d . The pH o f f i v e samples o f the o r i g i n a l u n t r e a t e d f a b r i c as w e l l as the C a ( O H ) 2 a n d MgOCVj b u f f e r s o l u t i o n s were a l s o m e a s u r e d . I n o r d e r t o determine whether the a l k a l i n e t r e a t m e n t s would e f f e c t i v e l y n e u t r a l i z e a c i d i c c o t t o n , f a b r i c e x p o s e d t o 50 M r a d s o f i o n i z i n g r a d i a t i o n was t r e a t e d i n t h e f o l l o w i n g manner b e f o r e measuring pH: (a)

Two 2 g r a m s a m p l e s o f 50 M r a d o o t o n were immersed i n 400 m l d i s t i l l e d w a t e r a t 2 5 ° C f o r 15 m i n u t e s , t h e p r o c e s s was r e p e a t e d and t h e n t h e s a m p l e s were d r i e d f l a t on g l a s s .

(b)

A f t e r r i n s i n g and d r y i n g a d d i t i o n a l s a m p l e s a s d e s c r i b e d a b o v e , two s a m p l e s were immersed i n e i t h e r MgC03 o r C a ( O H ) 2 s o l u t i o n ( l i q u o r t o f a b r i c r a t i o o f 9 0 : 1 ) f o r 10 m i n u t e s a t 2 4 ° C a n d t h e n d r i e d

f l a t on g l a s s . The a l k a l i n e l i q u o r s w e r e p r e p a r e d a s described previously. F a b r i c C o l o r Change: T h e c o l o r o f t h e a g e d s a m p l e s was assessed with a General E l e c t r i c Recording Spectrophotometer w h i c h m e a s u r e s t r i s t i m u l u s v a l u e s X , Y a n d Z and r e f l e c t a n c e . Color using

d i f f e r e n c e AE i n NBS u n i t s (AN 40 u n i t s ) was the Adams-Nickerson c o l o r d i f f e r e n c e formula

AE = 40 The

{(0.23AV ) y

terms V , x

and Z v a l u e s

V y and V

2

z

+ [A(V

x

-

V )] y

2

+ [0.4A(V

are modified Munsell X,

y

calculated (10, 1 1 ) : - V

)] } 2

z

Y

(11).


1 / 2

25.

kerr

et

al.

Fabric

361

Deterioration

R e s u l t s and D i s c u s s i o n F a b r i c Properties a f t e r Treatment. None o f t h e t r e a t m e n t s a l t e r e d f a b r i c c o l o r , and o n l y C a ( 0 H ) 2 h a r s h e n e d t h e f a b r i c hand. T h e s a m p l e s e x p o s e d t o m o r p h o l i n e v a p o r were s i g n i f i c a n t l y w e a k e r (87% o f t h e o r i g i n a l s t r e n g t h ) t h a n f a b r i c treated with water. Fabric Strength. The s t r e n g t h r e t e n t i o n o f t r e a t e d c o t t o n aged under v a r i o u s c o n d i t i o n s i s g i v e n i n T a b l e 1. The v a l u e s r e p o r t e d a r e an a v e r a g e o f s i x b r e a k s f o r imaged samples ( 5 b r e a k s f o r water t r e a t e d ) and a t l e a s t t h r e e breaks f o r a r t i f i c i a l l y aged s a m p l e s . T h e s t a n d a r d d e v i a t i o n and t h e c o e f f i c i e n t o f v a r i a t i o n f o r e a c h t r e a t m e n t and a g i n g p e r i o d was calculated. A p o o l e d s t a n d a r d d e v i a t i o n , T h e s t r e n g t h l o s s o f f a b r i c s h e a t e d a t 100°C a n d 100% R . H . a s a f u n c t i o n o f t i m e a r e shown i n F i g u r e s 1 , 2 , and 3 f o r C a ( O H ) 2 , M3CO3 a n d m o r p h o l i n e , r e s p e c t i v e l y . Crily Ca(OH)2 s i g n i f i c a n t l y d e c r e a s e s t h e r a t e o f d e g r a d a t i o n . A f t e r 600 h o u r s h e a t i n g , t h e f a b r i c t r e a t e d w i t h Ca(OH)2 r e t a i n e d 49% o f i t s o r i g i n a l s t r e n g t h w h i l e a l l o t h e r s a m p l e s r e t a i n e d o n l y a p p r o x i m a t e l y 10% o f t h e i r o r i g i n a l s t r e n g t h . H i g h h u m i d i t y a p p e a r s t o be n e c e s s a r y t o e n a b l e t h e a n i o n s t o d i f f u s e i n t o t h e c o t t o n f i b e r s and r e d u c e f a b r i c a c i d i t y , aging a t 50% r e l a t i v e h u m i d i t y d i d n o t a p p e a r t o p r o v i d e s u f f i c i e n t



170°C,

Dry,

360

600

100% R H , 1 0 0 ° C ,

100% R H , 1 0 0 ° C ,

hours

hours

hours

hours

10

42

75

84

97

20

84

b

b

3

9

49*

79

71*

93

19

91

93

102

101

MgC0

49*

69*

93*

84

93

18

87

96

100

102

Treatment Ca(OH)

(%) o f T r e a t e d F a b r i c s A f t e r

n

Heating

8

38

77

75*

94

18

85

85*

94

87*

Morpholine

D

f k v e r a g e o f s i x b r e a k s f o r u n h e a t e d s a m p l e s and t h r e e b r e a k s f o r h e a t e d s a m p l e s ( e x c e p t a s n o t e d ) . Average of 7 breaks * S i g n i f i c a n t l y d i f f e r e n t a t t h e 95% c o n f i d e n c e l e v e l f r o m a g e d w a t e r - t r e a t e d s a m p l e s b a s e d o n p o o l e d s t a n d a r d d e v i a t i o n a = 4.7%.

120

120

50% R H , 1 0 0 ° C ,

hours

100% R H , 1 0 0 ° C ,

50

hours

hours

50% R H , 1 0 0 ° C ,

116

600

93

100°C,

hours

Dry,

120

100°C,

f

Dry

hours 96

50

100°C,

Dry,

Water

Strength Retention

100

Conditions

I.

None

Heating

Table

25.

KERR

Fabric

E T A L .

Deterioration

lOO^C j

IOO°/o R . H .

IOO

z §

Ik

O

x

8 0

60

4

0

I-

o z

III

2 0

_

QC

O

WATER

&

Co(OH) I

(0

O

120

2

JL 360

AGING TIME Figure 1.

600

(HOURS)

Strength of cotton print cloth pretreated with Ca(OH) or water as a function of time of heating at 100°C and 100% R.H. 2

IOO»C

IOO*/* R . H .

IOO

< Z SO

c o

ft.

o

X

60

40

I© z

III c

H 01

20

O

WATER

#

MgCO,

-L

L. ISO AGING

360 TIME

600

(HOURS)

Figure 3. Strength of cotton print cloth pretreated with morpholine vapor or water as a function of time of heating at 100°C and 100% R.H.


364

DURABILITY O F M A C R O M O L E C U L A R M A T E R I A L S

J O

I

120 AGING

Figure 2.

I

I

360 TIME

L 600

(HOURS)

Strength of cotton print cloth pretreated with MgCO or water as a function of time of heating at 100° C and 100% R.H. s


25.

KERR E T A L .

Fabric

Deterioration

365

m o i s t u r e t o m o b i l i z e t h e a n i o n s a s t r e a t e d s a m p l e s were n o t s i g n i f i c a n t l y s t r o n g e r than the water t r e a t e d c o n t r o l s . F a b r i c p H . T h e pH o f s a m p l e s t r e a t e d w i t h v a r i o u s a l k a l i n e a g e n t s and t h e n aged i s r e p o r t e d i n T a b l e I I . Both exposure to h i g h h e a t ( 1 7 0 ° C ) a n d l o n g t e r m h e a t i n g a t 100°C c a u s e c o t t o n t o become a c i d i c . The p r e s e n c e o f an a l k a l i n e b u f f e r such a s C a ( 0 H ) 2 o r M3CO3 o n t h e c o t t o n w h i l e i t a g e s a s s i s t s i n r e d u c i n g the development o f a c i d i t y . The Ca(0H)2 t r e a t m e n t was m o s t e f f e c t i v e i n m a i n t a i n i n g a n a l k a l i n e p H . Samples t r e a t e d w i t h t h i s agent remained a l k a l i n e during, a l l o f the a g i n g e x p e r i m e n t s , and t h e s e s a m p l e s e x h i b i t e d t h e l e a s t l o s s i n strength. T h e pH o f 50 M r a d c o t t o n t r e a t e d w i t h d i s t i l l e d w a t e r , Mg3 a n d Ca(OH)2 i s r e p o r t e d i n T a b l e I I . Simply r i n s i n g t h e 50 M r a d c o t t o n w i t h d i s t i l l e d w a t e r f o r 30 m i n u t e s r a i s e d t h e pH f r o m 4 . 3 t o 5 . 5 . R i n s i n g w i t h w a t e r and t h e n t r e a t i n g w i t h M3CO3 d i d n o t n e u t r a l i z e t h e f a b r i c . Because o f t h e l o w s o l u b i l i t y o f M3CO3 i n w a t e r and t h e f a c t t h a t t h i s b u f f e r s o l u t i o n h a d a pH o f 8 . 5 c o m p a r e d w i t h 1 2 . 4 f o r t h e Ca(OH>2 s o l u t i o n , i t i s l i k e l y t h a t r e p e a t e d a p p l i c a t i o n o f MgC03 w o u l d be n e c e s s a r y t o n e u t r a l i z e a n a c i d i c f a b r i c . T h e Ca(OH)2 t r e a t m e n t r a i s e d t h e f a b r i c pH t o 9 . 0 b u t a l s o y e l l o w e d t h e 50 M r a d d e g r a d e d f a b r i c . Hey (_3) r e p o r t s t h a t p a p e r i s o c c a s i o n a l l y y e l l o w e d b y i m m e r s i o n i n Ca(OH)2r and t h e y e l l o w c o l o r d e v e l o p e d d u r i n g e x t r a c t i o n i n sodium b i c a r b o n a t e h a s b e e n u s e d t o d e t e r m i n e t h e C\ a l d e h y d e content i n oxidized cotton (14). Fabric Yellowing. T h e c o l o r c h a n g e ( i n NBS H u t s ) o f f a b r i c s t r e a t e d w i t h a l k a l i n e a g e n t s and e x p o s e d t o h e a t i s r e p o r t e d i n T a b l e I I I . A c o l o r c h a n g e o f 4 NBS u n i t s r e p r e s e n t s a " s l i g h t c h a n g e " i n c o l o r o r a r a t i n g o f 4 o n t h e AATCC G r e y S c a l e for E v a l u a t i n g C o l o r C h a n g e , w h i l e a d i f f e r e n c e o f 12 NBS u n i t s i s equivalent to a Grey Scale rating of 2 (10). Exposure o f c o t t o n t o h e a t c a u s e s i t t o change from a creamy w h i t e t o a y e l l o w brown c o l o r . The c o l o r which d e v e l o p s depends on the a l k a l i n e t r e a t m e n t and t h e c o n d i t i o n s o f a g i n g i n c l u d i n g t e m p e r a t u r e , h u m i d i t y and t i m e . B o t h h i g h t e m p e r a t u r e s (>100°C) and h i g h h u m i d i t y a c c e l e r a t e t h e y e l l o w i n g o f c e l l u l o s e . These f i n d i n g s a g r e e w i t h t h e work o f o t h e r r e s e a r c h e r s ( 1 3 ) . However, i t i s i n t e r e s t i n g t o note t h a t l e s s y e l l o w i n g o c c u r s d u r i n g m o i s t a g i n g when s a m p l e s a r e p r e t r e a t e d w i t h Ca(OH)2 t h a n when p r e t r e a t e d w i t h MgCC>3, m o r p h o l i n e o r w a t e r . In f a c t , pretreatment with morpholine accelerates yellowing during e x p o s u r e t o h e a t a l t h o u g h no c o l o r c h a n g e o c c u r r e d when t h e s e s a m p l e s were f i r s t t r e a t e d w i t h m o r p h o l i n e v a p o r . Walker r e p o r t s t h a t f e w e r t h a n o n e p e r c e n t o f t h e 3000 b o o k s t r e a t e d w i t h m o r p h o l i n e a t t h e B a r r o w l a b o r a t o r y showed a n i n i t i a l c o l o r c h a n g e []_). He made no comments c o n c e r n i n g c o l o r c h a n g e s


Eby; Durability of Macromolecular Materials ACS Symposium Series; American Chemical Society: Washington, DC, 1979. 3

7.4 5.3 7.1 6.7 5.4 4.2

-

8.5 7.4 8.4 8.0 8.2 7.7 9.0

7.8 5.7 7.6 6.8 6.3 4.5 6.5

6.0 5.4 7.1 6.7 5.7 4.3

100°C,

170°C,

Dry,

Dry,

Cotton

600

100% R H , 1 0 0 ° C ,

50 M r a d

360

120

50% R H , 1 0 0 ° C ,

hours

hours

tours

hours

100% R H , 1 0 0 ° C ,

50

hours

hours

hours

50% R H , 1 0 0 ° C ,

116

600

120

5.5

7.8

8.4

7.8

7.2

100°C,

Dry,

4.3

8.0

8.7

8.0

hours

7.0

50

100°C,

Morpholine

Dry,

2

7.3

Treatment Ca(OH) MgC0

Heating

9.1

Water

Treated Fabrics After

7.1

None

pH o f

6.8

Conditions

II.

None

Heating

Table


600

100% R H , 1 0 0 ° C ,

hours

hours*

hours*

hours

two r e p l i c a t e

360

100% R H , 1 0 0 ° C ,

*A v e r a g e o f

120

120

50% R H , 1 0 0 ° C ,

hours

100% R H , 1 0 0 ° C ,

50

hours

50% R H , 1 0 0 ° C ,

600

experiments

38.7

43.1

24.8

20.4

19.2 31.5

11.6

4.4

10.6

6.0

2.1

100°C,

Dry,

2.2

3.0

3.0

hours

100°C,

Dry,

120

2.1

1.7

hours

0.4

3

33.2

27.4

16.8

10.5

2.9

3.5

2.2

1.5

0.3

2

43.9

34.1

19.2

11.1

8.3

6.0

5.4

3.6

0.2

of Treated Fabrics A f t e r Heating Treatment MgC0 Ca(QH) Morpholine

100°C,

Water

( i n NBS u n i t s )

Dry,

50

C o l o r Change

0.0

Conditions

III.

None

Heating

Table

>

i a

DURABILITY O F M A C R O M O L E C U L A R

368

MATERIALS

during heating. In a r e v i e w a r t i c l e on the y e l l o w i n g o f p a p e r , S p i n n e r (13) r e p o r t s t h a t a number o f r e s e a r c h e r s h a v e a s s o c i a t e d y e l l o w i n g of c e l l u l o s e with the presence o f aldehyde g r o u p s a t c a r b o n s two and t h r e e . L a t e r work b y A l b e c k , B e n - B a s s e t and L e w i n , a t t r i b u t e t h e y e l l o w c o l o r o f h o t a l k a l i n e e x t r a c t s from m o d i f i e d c o t t o n p r i m a r i l y t o the aldehyde c o n t e n t (14). Summary a n d

Conclusions

The a b i l i t y o f t h r e e a l k a l i n e agents t o r e t a r d the d e g r a d a t i o n o f c o t t o n exposed t o h e a t has been i n v e s t i g a t e d . The e f f e c t i v e n e s s o f e a c h a g e n t i s summarized i n T a b l e I V . M e a s u r e m e n t o f pH a f t e r a g i n g i n d i c a t e s t h a t C a ( 0 H ) 2 i s a b l e t o d e p o s i t an a l k a l i n e r e s e r v e o n c o t t o n . This alkalinity w i l l p r o t e c t c o t t o n from s t r e n g t h l o s s i f t h e r e i s s u f f i c i e n t m o i s t u r e p r e s e n t d u r i n g a g i n g t o m o b i l i z e t h e h y d r o x y l i o n s and e n a b l e them t o d i f f u s e i n t o t h e c o t t o n f i b e r s . The d i s a d v a n t a g e s a s s o c i a t e d w i t h t h e use o f Ca(0H)2# n a m e l y a h a r s h e n i n g o f f a b r i c hand and y e l l o w i n g i f u s e d t o d e a c i d i f y d e g r a d e d c o t t o n , m u s t a l s o be c o n s i d e r e d . However, s i n c e t r e a t m e n t w i t h C a ( 0 H ) 2 i s r e v e r s i b l e , t h e o r i g i n a l hand o f a f a b r i c s h o u l d be r e s t o r e d b y w a s h i n g w i t h d i s t i l l e d w a t e r . Table

IV.

Effect

o f D e a c i d i f y i n g Agents on P r o p e r t i e s Heated C o t t o n F a b r i c s

Characteristic

of

Agent MgCO Morpholine

Ca(QH) z

Reduces s t r e n g t h l o s s , m o i s t h e a t i n g Reduces s t r e n g t h l o s s , d r y h e a t i n g Extent of yellowing, moist heating Extent of yellowing, dry heating M a i n t a i n s pH > 7 . 0

yes no less varies yes

no no varies same no

no no greater greater no

Magnesium c a r b o n a t e i s l e s s e f f e c t i v e than Ca(0H)2 i n preventing strength loss during aging. Because o f i t s low s o l u b i l i t y i n water, i t i s d i f f i c u l t to deposit s u f f i c i e n t Mg(X>3 o n a f a b r i c t o p r o v i d e a g o o d a l k a l i n e r e s e r v e . It i s l i k e l y t h a t more t h a n o n e a p p l i c a t i o n o f a s a t u r a t e d s o l u t i o n w o u l d be n e c e s s a r y t o n e u t r a l i z e a c i d i c c o t t o n . A l t h o u g h morpholine i s f r e q u e n t l y used i n d e a c i d i f y i n g paper and has a d i s t i n c t advantage i n t h a t i t can be a p p l i e d from the v a p o r p h a s e , i t h a s n o t p r o v e n t o be s u i t a b l e f o r use o n c o t t o n fabrics. Even a s h o r t exposure to morpholine enhances y e l l o w i n g d u r i n g a g i n g and a c c e l e r a t e s l o s s i n s t r e n g t h .


25.

KERR

E TA L .

Fabric

Deterioration

369

Literature Cited 1. Berry, G. M., Hersh, S. P., TUcker, P. A., Walsh, W. K., "Reinforcing Degraded Textiles Part I: Properties of Naturally and ArtificiallyAgedCotton Textiles," Adv. Chem. (1977) 164, 228-248. 2. Berry, G. M.,Hersh,S. P.,Tucker,P. A., Walsh, W. K., "Reinforcing Degraded Textiles Part II: Properties of Resin Treated ArtificiallyAgedCottonTextiles,"Adv. Chem. (1977) 104, 249-260. 3. Hey, Margaret,"TheDeacidification and Stabilization of Iron Gall Inks - Cellulose Combinations on Paper," a paper delivered at the A.I.C. 5th Annual Meeting, Boston, Mass., May 30 - June 2, 1977. 4. Kelly, George B.,"PracticalAspects of Deacidification," IIC-AG Paper, Conference at the American Philosophical Society, Philadelphia, Penn., 1972. 5. Kusterer, J. K. and Sproull, R. C.,"GaseousDiffusion Paper Deacidification," U.S. Patent 3,771,958, Nov. 13, 1973. 6. Walker, B. P. and Kusterer, J. K.,"Processfor Deacidifying a Book which Has a Pyroxylin-containing Cover," U.S. Patent 3,837,804, Sept. 24, 1974. 7. Walker, B. F.,"MorpholineDeacidification of Whole Books," Adv. Chen. (1977) 164, 72-78. 8. Weast, R. C.,"Handbookof Chemistry andPhysics,"CRC Press, Cleveland, Chio, 1974, E-46. 9. "1977 Annual Book of ASTM Standards, Part24,"American Society for Testing and Materials, Philadelphia, 1977. 10. AATCC Technical Manual, Vol. 53, AATCC, Research Triangle Park, 1977, 103. 11. McLaren, K."Adams-NickersonColor Difference Formula," J . Soc. Dyers and Colorists (1970) 86, 354-366. 12. Morris, M. A. "Effect of Weathering on Cotton Fabrics," California Agricultural Experiment Station Bulletin 823, Davis, 1966. 13. Spinner, I. H.,"BrightnessReversion,"TAPPI (1962) 45, 495-513. 14. Albeck, M., Ben-Bassat, A. and Lewin, M.,"TheYellowing of Cotton Cellulose Part II: The Influence of Functional Groups and the Nature ofYellowing,"Textile Research J. (1965) 35, 935-942. This is the third part of a series. RECEIVED

December 8, 1978.


Reinforcing Degraded Textiles: Effect of Deacidification on Fabric

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