I
ROY L. WHISTLER and
G. N.
RICHARDS
Department of Biochemistry, Purdue University, Lafayette, Ind.
Fibers from Amylose Triacetate
INDUSTRIAL
USES of cellulose and the potential uses of amylose are markedly similar. Also, the chemistry of both compounds is alike-they are linear polymers of 1,Clinked D-glucopyranose units, but the stereoconfiguration of the glycosidic bond ’ which links the ring units together differs-beta in cellulose, but alpha in amylose. Amylose alone forms strong films (7) of potential usefulness, but its triacetate films have stress-strain characteristics similar to those of cellulose triacetate ( 5 ) . Amylose triacetate film, like that from cellulose acetate undergoes orientation (6) when drawn. Films from mixed esters of cellulose dnd amylose are also similar (8). Starch is ,an abundant raw material, but inexpensive methods to separate its constituent polymers have not been found. Geneticists have raised the amylose content of cornstarch from 25% to 75 and SO%, and because a high amylose starch could be produced for nearly the same cost as normal starch, new genetic varieties are promising as a low cost source of amylose. Commercial carnstarch was defatted by extraction with methanol in a continuous extractor (7), fractionated with I-butanol (Z), and recrystallized twice more from water saturated with l-butanol. Finely powdered amylose, isolated in a finely powdered form from the butanol-amylose complex by washing with four successive portions of ethyl alcohol and drying over calcium chloride, had a intrinsic viscosity a t 25’ C. of 1 . 1 0 in 1N potassium hydroxide. After acetylated as described earlier (4), it was highly fibrous and odorless
Table 1.
Bobbin Denier 1 2 3
CD CT a
72.8 78.8 78.2 75 75
Tens., G./D. 0.56 0.54 0.50 1.30 1.2-1.4
when dried overnight at 40’ C. in vacuum over calcium chloride. The bulk material from several preparations had 62.7% of acetic acid and an [qJ25 of 1.66 in chloroform. A solution of 25 grams of amylose triacetate in 50 ml. of chloroform, spun from a 10-hole jet under a pressure of 100 to 150 P A . , produced highly lustrous filaments of about 7 denier. These were similar in appearance to those from cellulose acetate prepared under the same conditions, FiBments for mechanical testing were spun from 27% methylene chloride solution having a viscosity of 960 poises at- 25’ C. Tensile strength was tested for a 75-denier, 20-filament yarn using a 6-inch gage length and a strain rate of 67% per minute in a room conditioned to 65% relative humidity and 21’ C. Results are averages of five breaks (Table I). Single lengths of yarn (3 to 6 inches) were stretched mechanically at 25’ C. to produce a 25% elongation during 10 minutes, which was maintained for 20 minutes longer. These yarns were also stretched in water at 80’ C. to produce 50% elongation during 3 minutes, which was maintained 5 minutes longer. In water, breakage occurred a t about 140% elongation. Stretched yarns were tested with a length of 1.5 inches at 23’ C. and 22% relative humidity. Before stretching, their denier was 74.6 and reduction in denier was assumed proportional to elongation (Table 11). Results are the mean of five determinations. Undrawn yarns have lower tensile
Properties of Amylose Triacetate Yarn
Elong., % 64.4 66.4 56.9 28.0 25-28
Init. Mod.@,
Knot St.,
G./D.
G./D.
19.2 19.3 19.6 41.0 35-40
0.53 0.54 0.53 1.1 1.0-1.2
Knot Elong., % ”
‘63.6 66.3 62.2 22.0
Young’s: CD = cellulose diaoetate; CT = cellulose triacetate.
Loop
Loop
St.,
Elong., %
0.54 0.56 0.51 1.23 1.1-1.2
64.8 64.0 59.6 26.0
am.
Table II. Conditions of
Extension Unstretched (a)
(b)
Stretched Yarn
Exten- Tension at Break sion G. G./d. 0 25% 50%
42 39 35
0.’55 0.65 0.71
strengths than cellulose acetate yarns but much greater elongation at break (Table I). Hence, under proper drawing, the fibers might be orientated to give yarns of similar strength to those from cellulose acetate (Table 11). With yarn having heavier filaments, more extensive drawing and higher strengths would be likely. Generally, amylose triacetate films and fibers have greater flexibility and extensibility than similar products from cellulose acetate. Although triacetate fibers might be producible with properties similar to those of cellulose acetate fibers, they seem to show no superior properties. Use of cellulose acetate fibers has been decreasing in recent years and therefore the future of similar fibers from amylose acetate does not seem bright. However, because of their greater solubility and digestibility, fibers produced from amylose alone might find special industrial uses. Acknowledgment
The authors wish to thank the Celanese Corp. for spinning the fibers from amylose triacetate and for providing the data shown in Table I. Liierature Cited (I) Schoch, T. J., J. Am. Chem. SOC.64, 3954 11947’1 , - -,. ~ ( 2 ) b i d . , 64, 2957 (1942). (3) Whistler, R. L., unpublished work. (4) Whistler, R. L., Adv. in Carbohydrate Chem. 1, 285 (1945). (5) Whistler, R. L., Hilbert, G. E., IND. ENG.CHEM.36, 796 (1944). (6) Whistler, R. L., Schieltz, N. C., J. Am. Chem. Sac. 65, 1436 (1943). (7) Wolff, 1. A., Davis, H. A., Cluskey, J. E., Gundrum, L. J., Rist, C. E., IND. ENG.CHEM.43, 915 (1951). (8) Wolff, I. A., Olds, D. W., Hilbert, G. E., Zbid. 49, 1247 (1957). RECEIVED for review March 15, 1958 ACCEPTEDJuly 24, 1958 VOL. 50, NO. 10
OCTOBER 1958
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