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Study of methacrylamide grafting onto cellulose triacetate films under ultraviolet light
STUDY OF METHACRYLAMIDE GRAFTING ONTO CELLULOSE TRIACETATE FILMS UNDER ULTRAVIOLET LIGHT* S. K . KUDRI~_ Leningrad Institute of Cinema Engineers
(Received 29 October 1965)
Al~ EARLIER investigation [1] of the grafting of methacrylamide onto the surface of cellulose triacetate films using U V irradiation had shown that the grafting gave rise to an insoluble graft copolymer in the form of a surface film. The s t u d y of the acidity changes of the cellulose triacetate (CTA) film during UV irradiation had led to the theory that the free radicals which initiate the grafting are created at the points of acyl radical dissociation. The formation of free radicals in CTA could also take place on glucoside bond fracture or the liberation of an a-hydrogen atom from the main chain. Glucoside chain fracture in CTA can be detected with UV absorption at 2480 A and below [2]. The same fracture, b u t in the cellulose molecule, takes place at 2537 [3] or 2660 A [4, 5]. The aim of this work was to determine the wavelength of the UV light which would lead to the formation of sufficiently reactive free radicals to initiate the g r a f t c o p o l y m e r i z a t i o n o f m e t h a c r y l a m i d e w i t h t h e s u r f a c e o f C T A films.
EXPERIMENAL CTA with a bound acetic acid convent of 61"9% was used to prepare 0.1 m m thick films by pouring its solution in 9 : 1 methylene dichloride and methanol on to the surface of mirror glass. F o r m a t i o n of the film from solution and its drying were carried out in a nitrogen atmosphere. A 9% concentration of benzophenone on TCA was used in the solution as t h e photo-sensitizer. The films were irradiated with U V light in the presence of the methacrylamide (MAA) solution using a Tesla Tube TNK-700 on an assembly described earlier [1]. _An optical filter consisting of a number of films of the same composition as t h a t subjected to grafting was placed between the TCA film and the light source. B y varying the thickness of this one could alter the total thickness of the filter and thus also the spectral composition of the radiation. A uranyl oxalate actinometer was placed together with the film under test in the chamber filled with nitrogen. The irradiated film was removed from the chamber, washed with distilled water and left for 16 hr in water at 40°C to remove any homopolymcr (MAA). The film was then dried for 1 hr at 90°C and left for 24 hr in a 9 : 1 mixture of methylene dichloride with methanol to remove the uncopolymerized CTA. The solution was prepared * Vysokomol. soyed. 8: NO. 10, 1823-1827, 1966. 2011
2012
S . K . KUDRNA
in both cases by mixing with a magnetic stirrer. The insoluble graft copolymer which remained was dried to constant weight and the weight per unit of irradiated surface of the original film was determined. Titration of the actinometrie solution by the usual method [6] gave the irradiation intensity per unit surface area of the filter. Confirmation of the dependence of grafting on irradiation intensity was obtained by using the same apparatus and method, but different types of filter. The optical filter was in this work placed between the light source and the sample, and also between the light source and the actinometer, i.e. the irradiation intensity was measured directly. RESULTS
P r e l i m i n a r y experiments h a d confirmed the t h e o r y t h a t the a m o u n t of graft copolymer, P, was proportional to the square root of UV light intensity:
P=A' ad
(i)
Where the UV light was filtered first, its i n t e n s i t y at the surface of the film would obey the L a m b e r t - B e e r rule according to:
l~rad=lO"e-kzd,
(2)
in which t 0 is the i n t e n s i t y of UV light before filtering, d - - t h i c k n e s s of the filter. B y combining equations (1) a n d (2), using the derivation A . x/I0----B, one gets (3)
P = B " e-kad12
which, t r a n s f o r m e d into logarithms, gives finally log P----log B - - (b~14-606). d
(4)
The plotting of grafting as a function of thickness of the filtering film will t h u s be a straight line. The experimental results (Fig. 1) fully confirmed this theory. The slope of this line is, according to equation (4), proportional to the extinction coefficient o f the filter for the w a v e l e n g t h of the UV light. A more exact d e t e r m i n a t i o n of
~p J
O5
O
0
,
' O
1
-05 -I'0
Fro.
1. Grafting as a function of the thickness of the filtering layer.
Study of methacrylamide grafting onto cellulose triacetate films
2013
this coefficient was made by processing the experimental data by the method of least squares, taking into account that
the line does not pass through
the
c o o r d i n a t e o r i g i n . T h e r e s u l t s o f t h i s p r o c e s s i n g a r e s h o w n i n T a b l e 1.
TABLE
1. M E T H A C R Y L A M I D E
GRAFTING
TO
CTA
FILM AS A FUNCTION
OF ]~rLTERINO LAYER
THICKNESS
Arbitrary symbols for processing by the m e t h o d of least squares, n
X~
Y~
d
P
thickness of filtering layer, mm
quantity of gra~ eopolymer, mg/cm ~
log P
2 3 4 5 6 7 8 9 10 11 12 13 14
0 0-018 O.O35 0.040 0.055 0.085 0.100 0.105 0.115 0.141 0-175 0.215 0 0
5"34 3"95 3"19 2'66 1.72 1"51 1"16 0.812 1"15 0"504 0"184 0'096 5'41 5"32
0-727 0-596 0.503 0.424 0.235 0.179 0.064 --0.041 0.060 --0.298 --0.736 --1-022 0.733 0.725
Z
1.084
--
test No. 1
y,~
• ~, mm 2
2.149
0 0.00032 0.00122 0.00160 0.00302 0.00722 0.01000 0.01102 0.013225 0.01988 0.03062 0.04622 0 0
0.5285 0"3552 0.2530 0.1798 0"0552 0.0320 0.0041 0"0017 0.0036 0.0888 0.5417 1"0445 0.5372 0.5256
0 0"01073 0"01760 0"01696 0"01292 0"0152I 0"00640 --0"00431 0"0069 0"04202 --0"12880 --0"21973 0 0
0.14434
4.1509
--0.31814
Io= 16.2 × lO~hv/cm~.scc; t - 24°C; c~I- 19.5% w/w methacrylamide in water; tirrad = 10 rain. Using these results, one gets the direct correlation
byx ~
Z x~y ~ - Z x, Z y, n Z x ~ - ( Z xi)"o
x~Yi mm
=-s.ol
the constant
bo__~f l Yi--by~ f f x i = 0 . 7 7 5 , n and the correlation factor
/n Z~-(Z ~,)~__o.9999.
,
9014
S . K . KUDRNA
T h e d e v i a t i o n f r o m t h e m e a n will be Sby~=
~l
~
- - p by×= ~ 0 . 2 6 . P
A f t e r inserting t h e various values into e q u a t i o n (4), one gets:
log 1 ) = 0 . 7 7 5 - - 8 . 0 1
d.
(5)
:By using t h e f o u n d correlation bye, t h e e x t i n c t i o n coefficient was calculated: kx=by~.4 . 6 0 6 = 3 6 . 8 9 ± 1.19 a n d the e q u i v a l e n t w a v e l e n g t h of the light was f o u n d f r o m the U V s p e c t r u m o f the film used in the grafting, k~, according to Fig. 2, is e q u i v a l e n t to a w a v e l e n g t h of 3130-3150 A. T h e second series o f tests was carried o u t u n d e r the same conditions on t h e same t y p e of film b y using different filters. T h e U V spectra of these filters are Shown in Fig. 3. T h e y were selected so t h a t a certain sector was isolated from t h e t o t a l s p e c t r u m . Consecutive irradiation o f the films t h r o u g h these filters a n d t h e d e t e r m i n a t i o n of the a m o u n t o f graft c o p o l y m e r t h u s p r o d u c e d m a d e it possible to select the m o s t effective p a r t of the s p e c t r u m initiating the grafting r e a c t i o n . T a b l e 2 gives t h e results of this series o f tests, which were carried out a t 24°C w i t h a 19.5% w/w m e t h a c r y l a m i d e concentration. T A B L E 2. COI~PARISOI~" O)" T H E O R A F T I N G R E S U L T S W H E N FILTERING: T H E I N I T I A T I N G R A D I A T I O N
Filter No.
Type of filter
m
2 mm Si-glass 0.2 ram CTA film 1 cm layer of benzene 2 mm "Kavalier" glass 3130 /~ filter
Amount of graft copolymer, mg/cm 2
measured
calculated
graphed
5.38 3.98 2.63 1.70
16"2 × 10TM 14"9 × 10TM 11.4× 10TM 9"9 × 10TM
16-2 × 10TM 8"8 X 10'6 3"9 × 1016 1'6 × 1016
9"1 × 10le 7"5 × 10TM 5"6 × 1016 1"9 × 10TM
0 0.92
4:.5 × 10TM 1"7 × l0 TM
0 0"5 × 10TM
0 0"6 × 1016
Iirrad
T h e i r r a d i a t i o n t i m e was in all e x p e r i m e n t s 10 min. T h e irradiation i n t e n s i t y was calculated b y inserting into e q u a t i o n (1) the f o u n d quantities of g r a f t copolymer. Grafting tests w i t h o u t light filtering gave t h e coefficient A ~ 1.34 × 10 -s mg- sec½/h7½. 4 I t is t h o u g h t [6] t h a t the u r a n y l oxalate a c t i n o m e t e r is sensitive to radiation in t h e range 2000-4000 /~. A graphic c o m p a r i s o n (Fig, 3) of the whole surface a r e a o f the s p e c t r u m with the m e a s u r e d Iirrad-Value (without filtering) gave the light i n t e n s i t y b e h i n d the filter, taking i n t o a c c o u n t the surface area between t h e a b s o r p t i o n c u r v e and the 3130 ~ line.
Study of mothacrylamide grafting onto cellulose triaoetate film~
2015
As one c a n see f r o m T a b l e 2, no g r a f t i n g o c c u r r e d u p to 3130 A line. A direct r e l a t i o n s h i p r e m a i n e d b e t w e e n t h e a m o u n t of g r a f t c o p o l y m e r p r o d u c e d a n d t h e s q u a r e r o o t of light i n t e n s i t y in all o t h e r cases (if one includes in t h e calculation o n l y t h a t p a r t of U V light w i t h a w a v e l e n g t h s h o r t e r t h a n 3130 A). 2000
o
X,A
3000
4'000
2 X 150
4
t00
50 I
2000
02000
3000
,
4000~,~
~000 o
3130 A
FIG. 2 FIG. 3 FIG. 2. UV spectrum of a CTA film containing 9% benzophenone. FIe. 3. Characteristics of the filters used in the tests: 1--Si-glass, d=2 ram; 2--CTA-film without sensitizer, d=0.2 mm; 3--benzene layer in 1 cm Si-cell; 4--"Kavalier" glass, d = 2 mm; 5--3 cm layer of a solution composed of 46 g NiS04.6I=I20~14 g CoS04.7tt,O in 100 ml watcr~-1 cm layer of solution made of 5 g potassium phthalate in 1 1. water. A m o r e n o t i c e a b l e d e v i a t i o n f r o m this p r o p o r t i o n a l i t y can be seen in t e s t s No. 0 a n d 1. I r r a d i a t i o n a t a w a v e l e n g t h less t h a n 2500 A a p p e a r s to initiate a certain q u a n t i t y of free radicals o f a n o t h e r t y p e a n d this increased t h e g r a f t yield. T h e w a v e l e n g t h o f 3130 A, a t which g r a f t i n g begins, r e p r e s e n t s a r a d i a t i o n q u a n t u m e n e r g y o f 91.5 kcal/molc. This v a l u e is in g o o d a g r e e m e n t w i t h t h e e n e r g y of I t - - 0 b o n d dissociation [7, 8], which, in t h e C T A molecule, m e a n s t h a t t h e following b o n d s are f r a c t u r e d : O Cell" -{- "O--C--Ctt 3 0 hv
Cell-O-- --CHa --~
O
II
Cell-O" -b "C--CH3
2016
S.K. KUDRNA
This is in agreement with the results obtained earlier [1]. Furthermore, the activ ity of a wavelength of 3130 A with respect to the carbonyl group was shown b y Guillet and Norrish [9] in the photo-decomposition of polymethylvinylketone. CONCLUSIONS
(1) The graft copolymerization of cellulose triacetate with methacrylamide is shown to take place in UV light only at a wavelength shorter t h a n 3130 A. (2) A met hod is given to determine the effective wavelength of UV light which is based on selective filtering of the beam b y films of the same polymer as t h a t on which the grafting is to be produced. (3) A comparison of the effective q u a n t u m energies of UV light with the energy of dissociation of chemical bonds confirmed the earlier assumption t h a t free radicals are produced on the surface of the film at the point of dissociation; these are acyl groups or acetyl group fragments. Translated by K. A. A ~ y .
REFERENCES
1. S. K. KUDRNA, Vysokomol. soyed. 7: 557, 1965 (Translated in Poly. Sci. U.S.S.R, 7: 3, 617, 1965) 2. S. K. KUDRNA, Trudy Leningrad. Inst. Ki~oinzhenerov. Sbornik 12, 1966 3. G. S. EGGERTON, E. ATTLE and M. A. RATHOR, Nature 194: 968, 1962 4. F. H. FLYNN and W. L. MORROW, J. Polymer Sci. A2: 81, 1964 5. A. BE]~LIK and J. HAMILTON, Das Papier 13: 77, 1959 6. Sbornik: Kataliticheskiyc, fotokhimieheskiye i elektrokhimicheskiye reaktsii. (Collection: Catalytic, Photochemical and Electrochemical Reactions.) Foreign Lit. Publ. House, 1960 7. K. MORTIMER, Teploty reaktsii i prochnost' svyazei. (Heats of Reactions and the Strength of Bonds.) Izdat "Mir", Moscow, 1964 8. Ch. WOLLING, Svobodnye racUkaly v rastvore. (Free Radicals in Solution.) Foreign Lit. Publ. House, 1960 9. J. E. GUILLET and R. G. W. NORRISH, Nature 173: 625, 1954
(Received 29 October 1965)
Al~ EARLIER investigation [1] of the grafting of methacrylamide onto the surface of cellulose triacetate films using U V irradiation had shown that the grafting gave rise to an insoluble graft copolymer in the form of a surface film. The s t u d y of the acidity changes of the cellulose triacetate (CTA) film during UV irradiation had led to the theory that the free radicals which initiate the grafting are created at the points of acyl radical dissociation. The formation of free radicals in CTA could also take place on glucoside bond fracture or the liberation of an a-hydrogen atom from the main chain. Glucoside chain fracture in CTA can be detected with UV absorption at 2480 A and below [2]. The same fracture, b u t in the cellulose molecule, takes place at 2537 [3] or 2660 A [4, 5]. The aim of this work was to determine the wavelength of the UV light which would lead to the formation of sufficiently reactive free radicals to initiate the g r a f t c o p o l y m e r i z a t i o n o f m e t h a c r y l a m i d e w i t h t h e s u r f a c e o f C T A films.
EXPERIMENAL CTA with a bound acetic acid convent of 61"9% was used to prepare 0.1 m m thick films by pouring its solution in 9 : 1 methylene dichloride and methanol on to the surface of mirror glass. F o r m a t i o n of the film from solution and its drying were carried out in a nitrogen atmosphere. A 9% concentration of benzophenone on TCA was used in the solution as t h e photo-sensitizer. The films were irradiated with U V light in the presence of the methacrylamide (MAA) solution using a Tesla Tube TNK-700 on an assembly described earlier [1]. _An optical filter consisting of a number of films of the same composition as t h a t subjected to grafting was placed between the TCA film and the light source. B y varying the thickness of this one could alter the total thickness of the filter and thus also the spectral composition of the radiation. A uranyl oxalate actinometer was placed together with the film under test in the chamber filled with nitrogen. The irradiated film was removed from the chamber, washed with distilled water and left for 16 hr in water at 40°C to remove any homopolymcr (MAA). The film was then dried for 1 hr at 90°C and left for 24 hr in a 9 : 1 mixture of methylene dichloride with methanol to remove the uncopolymerized CTA. The solution was prepared * Vysokomol. soyed. 8: NO. 10, 1823-1827, 1966. 2011
2012
S . K . KUDRNA
in both cases by mixing with a magnetic stirrer. The insoluble graft copolymer which remained was dried to constant weight and the weight per unit of irradiated surface of the original film was determined. Titration of the actinometrie solution by the usual method [6] gave the irradiation intensity per unit surface area of the filter. Confirmation of the dependence of grafting on irradiation intensity was obtained by using the same apparatus and method, but different types of filter. The optical filter was in this work placed between the light source and the sample, and also between the light source and the actinometer, i.e. the irradiation intensity was measured directly. RESULTS
P r e l i m i n a r y experiments h a d confirmed the t h e o r y t h a t the a m o u n t of graft copolymer, P, was proportional to the square root of UV light intensity:
P=A' ad
(i)
Where the UV light was filtered first, its i n t e n s i t y at the surface of the film would obey the L a m b e r t - B e e r rule according to:
l~rad=lO"e-kzd,
(2)
in which t 0 is the i n t e n s i t y of UV light before filtering, d - - t h i c k n e s s of the filter. B y combining equations (1) a n d (2), using the derivation A . x/I0----B, one gets (3)
P = B " e-kad12
which, t r a n s f o r m e d into logarithms, gives finally log P----log B - - (b~14-606). d
(4)
The plotting of grafting as a function of thickness of the filtering film will t h u s be a straight line. The experimental results (Fig. 1) fully confirmed this theory. The slope of this line is, according to equation (4), proportional to the extinction coefficient o f the filter for the w a v e l e n g t h of the UV light. A more exact d e t e r m i n a t i o n of
~p J
O5
O
0
,
' O
1
-05 -I'0
Fro.
1. Grafting as a function of the thickness of the filtering layer.
Study of methacrylamide grafting onto cellulose triacetate films
2013
this coefficient was made by processing the experimental data by the method of least squares, taking into account that
the line does not pass through
the
c o o r d i n a t e o r i g i n . T h e r e s u l t s o f t h i s p r o c e s s i n g a r e s h o w n i n T a b l e 1.
TABLE
1. M E T H A C R Y L A M I D E
GRAFTING
TO
CTA
FILM AS A FUNCTION
OF ]~rLTERINO LAYER
THICKNESS
Arbitrary symbols for processing by the m e t h o d of least squares, n
X~
Y~
d
P
thickness of filtering layer, mm
quantity of gra~ eopolymer, mg/cm ~
log P
2 3 4 5 6 7 8 9 10 11 12 13 14
0 0-018 O.O35 0.040 0.055 0.085 0.100 0.105 0.115 0.141 0-175 0.215 0 0
5"34 3"95 3"19 2'66 1.72 1"51 1"16 0.812 1"15 0"504 0"184 0'096 5'41 5"32
0-727 0-596 0.503 0.424 0.235 0.179 0.064 --0.041 0.060 --0.298 --0.736 --1-022 0.733 0.725
Z
1.084
--
test No. 1
y,~
• ~, mm 2
2.149
0 0.00032 0.00122 0.00160 0.00302 0.00722 0.01000 0.01102 0.013225 0.01988 0.03062 0.04622 0 0
0.5285 0"3552 0.2530 0.1798 0"0552 0.0320 0.0041 0"0017 0.0036 0.0888 0.5417 1"0445 0.5372 0.5256
0 0"01073 0"01760 0"01696 0"01292 0"0152I 0"00640 --0"00431 0"0069 0"04202 --0"12880 --0"21973 0 0
0.14434
4.1509
--0.31814
Io= 16.2 × lO~hv/cm~.scc; t - 24°C; c~I- 19.5% w/w methacrylamide in water; tirrad = 10 rain. Using these results, one gets the direct correlation
byx ~
Z x~y ~ - Z x, Z y, n Z x ~ - ( Z xi)"o
x~Yi mm
=-s.ol
the constant
bo__~f l Yi--by~ f f x i = 0 . 7 7 5 , n and the correlation factor
/n Z~-(Z ~,)~__o.9999.
,
9014
S . K . KUDRNA
T h e d e v i a t i o n f r o m t h e m e a n will be Sby~=
~l
~
- - p by×= ~ 0 . 2 6 . P
A f t e r inserting t h e various values into e q u a t i o n (4), one gets:
log 1 ) = 0 . 7 7 5 - - 8 . 0 1
d.
(5)
:By using t h e f o u n d correlation bye, t h e e x t i n c t i o n coefficient was calculated: kx=by~.4 . 6 0 6 = 3 6 . 8 9 ± 1.19 a n d the e q u i v a l e n t w a v e l e n g t h of the light was f o u n d f r o m the U V s p e c t r u m o f the film used in the grafting, k~, according to Fig. 2, is e q u i v a l e n t to a w a v e l e n g t h of 3130-3150 A. T h e second series o f tests was carried o u t u n d e r the same conditions on t h e same t y p e of film b y using different filters. T h e U V spectra of these filters are Shown in Fig. 3. T h e y were selected so t h a t a certain sector was isolated from t h e t o t a l s p e c t r u m . Consecutive irradiation o f the films t h r o u g h these filters a n d t h e d e t e r m i n a t i o n of the a m o u n t o f graft c o p o l y m e r t h u s p r o d u c e d m a d e it possible to select the m o s t effective p a r t of the s p e c t r u m initiating the grafting r e a c t i o n . T a b l e 2 gives t h e results of this series o f tests, which were carried out a t 24°C w i t h a 19.5% w/w m e t h a c r y l a m i d e concentration. T A B L E 2. COI~PARISOI~" O)" T H E O R A F T I N G R E S U L T S W H E N FILTERING: T H E I N I T I A T I N G R A D I A T I O N
Filter No.
Type of filter
m
2 mm Si-glass 0.2 ram CTA film 1 cm layer of benzene 2 mm "Kavalier" glass 3130 /~ filter
Amount of graft copolymer, mg/cm 2
measured
calculated
graphed
5.38 3.98 2.63 1.70
16"2 × 10TM 14"9 × 10TM 11.4× 10TM 9"9 × 10TM
16-2 × 10TM 8"8 X 10'6 3"9 × 1016 1'6 × 1016
9"1 × 10le 7"5 × 10TM 5"6 × 1016 1"9 × 10TM
0 0.92
4:.5 × 10TM 1"7 × l0 TM
0 0"5 × 10TM
0 0"6 × 1016
Iirrad
T h e i r r a d i a t i o n t i m e was in all e x p e r i m e n t s 10 min. T h e irradiation i n t e n s i t y was calculated b y inserting into e q u a t i o n (1) the f o u n d quantities of g r a f t copolymer. Grafting tests w i t h o u t light filtering gave t h e coefficient A ~ 1.34 × 10 -s mg- sec½/h7½. 4 I t is t h o u g h t [6] t h a t the u r a n y l oxalate a c t i n o m e t e r is sensitive to radiation in t h e range 2000-4000 /~. A graphic c o m p a r i s o n (Fig, 3) of the whole surface a r e a o f the s p e c t r u m with the m e a s u r e d Iirrad-Value (without filtering) gave the light i n t e n s i t y b e h i n d the filter, taking i n t o a c c o u n t the surface area between t h e a b s o r p t i o n c u r v e and the 3130 ~ line.
Study of mothacrylamide grafting onto cellulose triaoetate film~
2015
As one c a n see f r o m T a b l e 2, no g r a f t i n g o c c u r r e d u p to 3130 A line. A direct r e l a t i o n s h i p r e m a i n e d b e t w e e n t h e a m o u n t of g r a f t c o p o l y m e r p r o d u c e d a n d t h e s q u a r e r o o t of light i n t e n s i t y in all o t h e r cases (if one includes in t h e calculation o n l y t h a t p a r t of U V light w i t h a w a v e l e n g t h s h o r t e r t h a n 3130 A). 2000
o
X,A
3000
4'000
2 X 150
4
t00
50 I
2000
02000
3000
,
4000~,~
~000 o
3130 A
FIG. 2 FIG. 3 FIG. 2. UV spectrum of a CTA film containing 9% benzophenone. FIe. 3. Characteristics of the filters used in the tests: 1--Si-glass, d=2 ram; 2--CTA-film without sensitizer, d=0.2 mm; 3--benzene layer in 1 cm Si-cell; 4--"Kavalier" glass, d = 2 mm; 5--3 cm layer of a solution composed of 46 g NiS04.6I=I20~14 g CoS04.7tt,O in 100 ml watcr~-1 cm layer of solution made of 5 g potassium phthalate in 1 1. water. A m o r e n o t i c e a b l e d e v i a t i o n f r o m this p r o p o r t i o n a l i t y can be seen in t e s t s No. 0 a n d 1. I r r a d i a t i o n a t a w a v e l e n g t h less t h a n 2500 A a p p e a r s to initiate a certain q u a n t i t y of free radicals o f a n o t h e r t y p e a n d this increased t h e g r a f t yield. T h e w a v e l e n g t h o f 3130 A, a t which g r a f t i n g begins, r e p r e s e n t s a r a d i a t i o n q u a n t u m e n e r g y o f 91.5 kcal/molc. This v a l u e is in g o o d a g r e e m e n t w i t h t h e e n e r g y of I t - - 0 b o n d dissociation [7, 8], which, in t h e C T A molecule, m e a n s t h a t t h e following b o n d s are f r a c t u r e d : O Cell" -{- "O--C--Ctt 3 0 hv
Cell-O-- --CHa --~
O
II
Cell-O" -b "C--CH3
2016
S.K. KUDRNA
This is in agreement with the results obtained earlier [1]. Furthermore, the activ ity of a wavelength of 3130 A with respect to the carbonyl group was shown b y Guillet and Norrish [9] in the photo-decomposition of polymethylvinylketone. CONCLUSIONS
(1) The graft copolymerization of cellulose triacetate with methacrylamide is shown to take place in UV light only at a wavelength shorter t h a n 3130 A. (2) A met hod is given to determine the effective wavelength of UV light which is based on selective filtering of the beam b y films of the same polymer as t h a t on which the grafting is to be produced. (3) A comparison of the effective q u a n t u m energies of UV light with the energy of dissociation of chemical bonds confirmed the earlier assumption t h a t free radicals are produced on the surface of the film at the point of dissociation; these are acyl groups or acetyl group fragments. Translated by K. A. A ~ y .
REFERENCES
1. S. K. KUDRNA, Vysokomol. soyed. 7: 557, 1965 (Translated in Poly. Sci. U.S.S.R, 7: 3, 617, 1965) 2. S. K. KUDRNA, Trudy Leningrad. Inst. Ki~oinzhenerov. Sbornik 12, 1966 3. G. S. EGGERTON, E. ATTLE and M. A. RATHOR, Nature 194: 968, 1962 4. F. H. FLYNN and W. L. MORROW, J. Polymer Sci. A2: 81, 1964 5. A. BE]~LIK and J. HAMILTON, Das Papier 13: 77, 1959 6. Sbornik: Kataliticheskiyc, fotokhimieheskiye i elektrokhimicheskiye reaktsii. (Collection: Catalytic, Photochemical and Electrochemical Reactions.) Foreign Lit. Publ. House, 1960 7. K. MORTIMER, Teploty reaktsii i prochnost' svyazei. (Heats of Reactions and the Strength of Bonds.) Izdat "Mir", Moscow, 1964 8. Ch. WOLLING, Svobodnye racUkaly v rastvore. (Free Radicals in Solution.) Foreign Lit. Publ. House, 1960 9. J. E. GUILLET and R. G. W. NORRISH, Nature 173: 625, 1954