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Graft copolymerization of nylon 6 with methylmethacrylate and methylacrylate I.

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Die Angewandte Makromolekulare Chemie 32 (1973) 81-90 ( N r . 456)
From the Indian Institute of Technology, Delhi, Hauz Khas,
New Delhi-29, India
Graft Copolymerization of Nylon 6 with Methylmethacrylate and Methylacrylate
I. Optimum Conditions of Grafting and Thermal Behaviour of the Copolymers
By D. S. VARMA
and N. D. RAY
(Received January 5, 1973)
SUMMARY:
Nylon 6 , 20 denier, monofilaments were grafted with methylmethacrylate and
methylacrylate using ceric ion/sulphuric acid as initiator. Grafted nylon samples
with different yo graft-on were prepared by varying the reaction conditions. The
thermal stabilities of these grafted samples were compared with parent nylon
using dynamic thermogravimetry in air a t a heating rate of 6 "C/min up to a
temperature of 550 "C. The initial decomposition temperature (IDT) integral
procedureal decomposition temperature (IPDT) and activation energy (E) values
indicated that thermal stability decreased as a result of grafting.
ZUSAMMENFASSUNG :
Nylon-6 wurde mit Methylmethacrylat und Methylacrylat unter Verwendung
von Cer-Ionen/Schwefels&ureals Initiator gepfropft. Proben mit verschiedenem
Pfropfungsgrad wurden durch Variation der Reaktionsbedingungen hergestellt.
Die thermische Stabilitat dieser gepfropften Produkte wurde im Vergleich ziim
Ausgangsnylon durch dynamische Thermogravimetry untersucht ; danach nimmt
die thermische Stabilitat als Folge der Pfropfung ab.
Introduction
The structure and properties of fibres can be modified by grafting with
suitable monomers. Grafting of nylon fibres by vinyl monomers has been
reported in the literaturel-13, and thermal behaviour of the grafted samples
has also been investigated. In the present work grafting of nylon 6 by methylacrylate and methylmethacrylate was carried out in presence of ceric ions a s
the initiator. The thermal behaviour of the grafted samples was investigated
by using dynamic thermogravimetry .
Experimental
Materials
The nylon 6 , monofilament of 20 denier, semi-dull (obtained from J. K. Synthetics
Ltd. Kota, Rajasthan, India), was extracted with petroleum ether for 12 hrs. to
81
D. S. VARMA
and N. D. RAY
remove grease and dirt, and was used. The BDH reagent grade monomers were
freed from the inhibitor by washing with alkali and water and dried over CaC12.
They were distilled before use.
Formic acid, analar grade was used for swelling of the nylon fibre. Ammonia
solution, analar grade was used for neutralization of the acid. Baker analyzed
reagent grade ceric ammonium sulphate and other chemicals of laboratory reagent
grade were used for grafting.
Pre-swelling
Nylon 6 filament was treated with 60% formic acid for 30 min, which acts as
a swelling agent. The filament was then washed with dilute ammonia and water.
Graft Copolymerization of Nylon 6
Graft copolymerization was carried out in a three necked flask in nitrogen
atmosphere. Nylon samples were immersed in a solution consisting of sulphuric
acid (0.25 N to 2 N) and ceric ammonium sulphate (0.001 N to 0.1 N) a t a temp.
of 60 "C. Monomer (2.5% to 15%) was added to the reaction mixture and the
contents of the flask were constantly stirred. Material to liquor ratio was 1:50 and
the reaction time was varied from 30 min to 8 hrs. After the reaction had proceeded
t o a desired interval of time, the sample was removed and washed in a stream of
tap water. The samples were soxhlet extracted with benzene or acetone and dried
in a n oven a t 105 "C for 5 hrs, cooled to the room temp. a,nd weighed. Grafting was
calculated as percent increase in weight over the original weight of the samples.
Thermogravimetric Analysis
The thermogravimetric analysis of the grafted and parent samples was done by
using a "Stanton Model HT-D Thermobalance" in air. The fibres were cut into
approximately 1/16 inch lengths and 50 & 2 mg sample was taken for each experiment. The samples were heated a t a uniform heating rate of 6 "C/min from room
temp. to a temp. of 550 "C. Primary thermograms were obtained by plotting
residual weight against temperature. The loss in weight occuring below 120 "C was
neglected as it may be due to the moisture.
Results and D~scussions
Egect of Acid Concentration
In Table 1, t h e effect of varying the acid concentration (from 0.25N t o
2 N) on the grafting of methylacrylate and methylmethacrylate on nylon 6 is
reported. It was observed t h a t grafting was maximum at a n optimum pH if
the acid concentration was increased or decreased from this optimum value, a
decrease in the yo grafting was taking place. Similar observations have been
reported on the grafting of vinyl monomers on cellulosel4-16 and nylonl. A
82
Graft Copolymerization of N y l o n 6
kinetic scheme has also been proposed to account. for i t l y 16. The present results can also be explained on similar grounds.
Table 1. Effect of sulphuric acid concentration on grafting of nylon 6 by methylmethacrylate and methylacrylate.
Methylmet hacrylate
Methy lacry late
63
81
52
49
23
37
59
70
58
52
0.25
0.50
0.75
1 .oo
1.50
2.00
-
Concentration of ceric ammonium sulphate in the bath 0.03 N for MMA and 0.07 N
for MA,
concentration of the Monomer: 5%,
time of swelling: 30 min,
temperature : 60 "C,
material: liquor = 1 :50,
reaction time: = 2 hrs.
Egect of Initiator Concentration
The effect of initiator concentration on grafting was studied by using different concentrations of ceric ammonium sulphate (0.001 N to 0.1 N). It was
observed that grafting increased progressively with increase in the initiator
concentration up to a concentration of 0.03 N in the case of methylmethacrylate and up to 0.07 N in the case of methylacrylate. At higher concentrations
of the initiator extent of grafting decreased as shown in Table 2. Similar results
were obtained by HAWORTH
et al.8 and VAEMAet al.1 while grafting vinyl
monomers onto nylon 6 by ceric ion method. This behaviour can be explained
on similar lines as reported earlierl.
Egect
of
Monomer Concentration
Nylon 6 fibres were treated with methylacrylate and methylmethacrylate
a t different concentrations ranging from 2.5% to 15%. As is obvious from
Table 3, the grafting increased with increase in the monomer concentration.
However, a t higher concentrations of the monomer, rate of homopolymerization
also increased and hence it became difficult to remove the homopolymer a t
higher monomer concentrations.
83
D. S. VARMA
and N. D. RAY
Ceric ammonium
sulphate normality
Graft-on
Methylmethacrylate
(yo)
Methylacry late
Concentration of acid in the bath: 0.5 N in the case of MMA, 1.00 N in the case
of MA,
concentration of the monomer: 5y0,
time of swelling: 30 min,
temperature : 60 "C,
reaction time: 2 hrs.,
material: liquor = 1 :50.
Monomer
concentration
(yo)
2.5
5.0
7.5
10.0
15.0
Graft-on
Methy imcthacrylate
62
81
88
92
93.5
(yo)
Methylacrylate
52
70
80
88
89
Concentration of ceric ammonium sulphate in the Lath: 0.03 N for MMA, 0.07 N
for MA,
concentration of HzS04: 0.5 N for MMA, 1.0 N for MA
reaction time: 2 hrs.,
temperature: 60 "C,
material: liquor = 1 :50,
time of swelling: 30 min.
Eflect of Reaction Time
Grafting was carried out a t different intervals of time. It was observed t h a t
grafting increased with time, though the rate of increase was not very high
a t higher intervals of time (Fig. 1). From these investigations it is obvious
84
Graft Copolymerization of Nylon 6
that a t 60 "C and 5% monomer concentration maximum grafting occurred a t
an acid concentration of 0.75 N in methylmethacrylate (catalyst concentration :
0.03 N) and 1 N in methylacrylate (catalyst concentration: 0.07 N).
REACTION
Fig. 1.
TIME
Effect of reaction time on grafting of nylon 6.
Thermogravimetric Analysis
The thermal behaviour of nylon 6 grafted with methylmethacrylate and
methylacrylate to various percentages of grafting was studied by comparing
their primary thermograms.
85
D. S. VARMA
and N. D. RAY
IOC
GRAFT
ON
\
*/.
37
57
70
79
8C
6C
4c
2c
0
2
I
280
I
I
36 0
TEMPERATURE
440
'C
J
52 0
_ _ f
Fig. 2 . Primary thermograms of parent nylon 6 and nylon 6 grafted with methylacrylate.
Primary thermograms of parent yarn and nylon 6 grafted with methylacrylate and methylmethacrylate are shown in Fig. 2 and 3. The temperature
of decomposition is very much influenced by the percentage graft-on in both
the cases. The decomposition temperature TD a t various degrees of grafting
is given in Table 4. Till about 80% decomposition the grafted samples degraded a t a lower temperature than the parent nylon. At 90% weight loss,
there was a remarkable improvement in the thermal stability. Thus 90%
weight loss was observed a t 456 "C in the parent yarn whereas it was 470 "C,
86
Graft Copolymerization of Nylon 6
GRAFT
\
\
ON
I.
0
2.
3.
4.
46
BI
92
5.
I02
I'.
I
3
200
TEMPERATURE
.C
-Lc
Fig. 3. Primary thermograms of parent nylon 6 and nylon 6 grafted with methy:methacrylate.
476 "C, 484 "C and 498 "C in the case of methylacrylate grafted nylon 6 with
37%, 57%, 70%, and 79% graft-on respectively. The decrease in thermal
stability up to 400 "C in the methylacrylate grafted nylon may be due to the
earlier decomposition of the polymethylacrylate, thus decreasing the overall
thermal stability of the grafted samples.
Nylon grafted with methylmethacrylate also showed a lower thermal
stability compared to the parent nylon up to 70% decomposition and the temperature of decomposition decreased as the percent graft-on increased.
87
D. S. VARMAand N. D. RAY
TD ("C) corresponding to the weight loss of
Samples
yo Graft-on
10
20
30
40
50
60
70
80
90
424
364
364
338
346
363
367
370
375
429
400
392
350
356
383
388
397
406
434
456
465
394
410
420
432
446
465
456
503
510
467
480
470
476
484
498
( O/O )
Parent garn
Methylmethacrylate
grafted nylon 6
Methylacrylate
grafted nylon 6
0
46
81
92
102
37
57
70
79
368
302
306
304
297
323
318
308
304
886
322
323
316
308
332
328
322
320
396
336
336
323
319
338
337
336
330
408
347
343
328
331
346
346
347
350
416
353
350
333
340
352
355
358
362
The increase in the thermal stability of grafted samples a t high percentage
decomposition may be due to partial cyclizations leading to stable ring structures as in the case of polyacrylonitrilel.
Initial decomposition temperature values (IDT) for parent yarn and nylon
grafted with methylacrylate and methylmethacrylate to various percentage
of grafting are given in Table 5. Grafted samples start decomposing earlier
than the parent yarn in both the cases. A decrease in IDT with increase in
graft-on percentage was observed.
Table 5. Thermogravimetric analysis of nylon 6 and grafted samples.
Sample
Parent nylon 6
Methylmethacrylate
grafted nylon 6
Methylacrylate
grafted nylon 6
Graft -on
(Yo)
IDT ("C)
0
46
81
92
102
37
57
70
79
280
270
265
265
260
257
245
240
235
IPDT ("C)
409
379
377
357
361
37 1
378
380
381
Activation energy
(kcal/mole)
54
47
64
73
70
64
54
53
52
The integral procedural decomposition temperature (IPDT) as proposed
by D O Y L Eto~ ~
find out the integral end of volatilization temperature was
calculated for the different grafted and parent samples from the thermograms (Table 5). IPDT values increased with increase in graft-on percent in the
case of methylacrylate grafted nylon 6 whereas in the case of methylmethacryl88
Graft Copolymerization of N y l o n 6
ate grafted nylon, the value of IPDT decreased with increase in graft-on
percent. However, the value of IPDT was greater for the parent nylon than
for the grafted one.
Activation energy was calculated for the decomposition reaction in the
temperature range of 250 "C t o 500 "C using the method given by DHARWADKAR
and KHARKHANAWALA~~.
Activation energies for parent yarn and nylon grafted
with methylacrylate and methylmethacrylate t o various degrees of grafting
are given in Table 5 .
I n the case of methylacrylate grafted nylon, activation energy is less than
the parent nylon, but withincreasing percentage ofgraft-on,thereisno appreciable
change in the value of activation energy. Nylon grafted with methylmethacrylate shows an increase in the value of activation energy with increase in percentage
graft-on and the grafted samples a t higher percentages of graft-on have activation energy higher than that of the parent nylon.
From the values of IDT, IPDT and E it can be concluded that the thermal
stability of nylon is decreased due to grafting with methylacrylate and methplmethacrylate. But a t higher percentage of graft-on thermal stabilities of the
grafted samples are comparable to the parent sample.
The authors are thankful to Mrs. VEENANARSIMHAN
for helping in the
preparation of the manuscript.
1
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13
14
15
16
17
D. S. VARMA
and S. RAVISANKAR,
Angew. Makromol. Chem. 28 (1973) 191
G. MINO and S. KAISERMAN,
J. Polym. Sci. 31 (1958) 242
K. SUZUKI,I. KIDO, N. TAKEKAWA,
and Y. YAMAZAKI,
Sen-i Gakkaishi 25
(1969) 515
G. J. HOWARD,
S. R. RINO,and R . H . PETERS,J. Soc. Dyers Colour. 85 (1969)
468
J. A. W. SYKESand J. K . THOMAS,
J. Polym. Sci. 55 (1961) 721
A. A. ARMSTRONG
and H. A. RUTHERFORD,
Text. Res. J. 33 (1963) 264
R . ROBERTS
and J. K. THOMAS,
J. SOC.Dyers Colour. 76 (1960) 342
S. HAWORTH
and J. R. HOLKER,
J. Soc. Dyers Colour. 82 (1966) 257
S. DASGUPTA,
J. T. SLOBODION,
and P. L. RAWAT,
Amer. Dyest. Rep. 51 (1962)
235
G. ODEON,M. SOBAL,
A. ROSSI,R . KLEIN,and T. ACKER,J. Polym. Sci. A 1
(1963) 639
D. S. BALLANTINE,
P. COLOMBO,
A. GLUSES,B. MONOWITZ,
and D. L. METZ,
Brookhaven National Lab. Rep. 414 (1956) T. 81
B. E. MAGAT, I. K. MILLER,D. JANNER,and J. ZIMMERMAN,
J. Polym. Sci.
C 4 (1963) 615
Y. SHINOHARA,
J. Appl. Polym. Sci. 11 (1957) 251
S. RANGARAOand S. L. KAPOOR,
J. Appl. Polym. Sci. 13 (1969) 2649
Y.OGIWARA,
Y.OGIWARA,
and H. KUBOTA,
J. Polym. Sci. A-1 5 (1967) 2791
D.S. VARMA
and VEENA
NARSIDIHAN,
J. Appl. Polym. Sci. 16 (1972) 3325
C. D. DOYLE,Anal. Chem. 33 (1961) 77
89
D. S. VARMA
and N. D. RAY
S. R . DHARWADKAR
and M. D. KARKHANAWALA,
“Thermal Analysis, Inorganic
Materials and Physical Chemistry”, Ed. Schwenker/Garn, Vol. 2, Academic
Press, New York 1969, p. 1049
90
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