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Latex deposition on fibers: Effect of electrolytes on rate and interaction energy
Latex Deposition on Fibers: Effect of Electrolytes on Rate and Interaction Energy 1 H I S A S H I TAMAI AND T O S H I R O S U Z A W A Department of Applied Chemistry, Faculty of Engineering, Hiroshima University, Senda-machi, Naka-ku, Hiroshima, 730, Japan Received March 10, 1981, accepted December 16, 1981 The rate of deposition of anionic polymethyl methacrylate latex on polyamide, polyester, and polyacrylonitrile fabrics and its relation to the interaction energy were investigated as a function of electrolyte concentration. With increasing the concentration of electrolytes, the total interaction energy between latex particles and fabrics decreased and the rates of deposition on polyamide and polyester fabrics increased. The rates of deposition on polyacrylonitrile fabric were constant above a certain concentration of electolytes. The rate constants of deposition on polyacrylonitrile fabric were constant below a certain value of the estimated maximum total interaction energy (Vrm~x) as a function of the separation distance between latex particles and fabric and decreased with further increasing Vr .... The rate constants on polyamide fabric and polyester fabric decreased gradually with increasing Vr .... however, latex particles deposited in spite of large values estimated for Vr .... At the same value of Vrmax with respect to the three kinds of fabrics, the rate constants decreased in the order of polyacrylonitrile fabric, polyamide fabric, and polyester fabric. INTRODUCTION
A heterocoagulation theory has been proposed by Derjaguin (1), and Hogg, Healy, and Fuerstenau ( H H F ) (2). Recently, Barouch et al. (3) have determined the interaction energy of unequal spheres by employing the Poisson-Boltzmann equation in its two- dimensional form, and their theoretical results have been compared with experimental data (4, 5). Since the deposition of latex particles on fibers is assumed to be a heterocoagulation between fibers and latex particles, the deposition is probably influenced by the interaction energy of electrical double layers and van der Waals forces between both substances. Thus, the theoretical interpretation of latex deposition may be aid by application of heterocoagulation theory. This paper is Part IV in a series "Interfacial electrical studies on the deposition of polymer latexes onto fabrics and the removal of these deposited latexes"; Part III: H. Tamai and T. Suzawa, Colloid Polym. Sci., 259, l l 0 0 (1981).
From these points of view, on the deposition of anionic polystyrene latex and polymethyl methacrylate ( P M M A ) latex on fibers, the change of the interaction energy between fibers and latex particles as a function of pH has been estimated using the H H F approximate solution for the interaction of dissimilar materials (6, 7). In addition, the relation between their interaction energy and the amount deposited of latex, the rate of deposition and the state of latex particles deposited on fibers have been considered (6-8). Further, it is important that the effects of the kind and the concentration of electrolytes on the deposition are considered, because the stability of latex is remarkably influenced by those factors. In this paper, on the deposition of anionic P M M A latex on fibers, the relation between the rate of deposition and the interaction energy as a function of electrolyte concentration is reported. Sodium chloride and sodium sulfate were used as electrolytes, and 372
0021-9797/82/080372-0652.00/0 Copyright© 1982 by AcademicPress, Inc, All rightsof reproductionin any form reserved.
Journalof ColloidandInterfaceScience,Vol. 88, No. 2, August 1982
373
DEPOSITION OF LATEX ON FIBERS
the interaction energy was estimated by heterocoagulation theory using the H H F approximation (1). EXPERIMENTAL
Materials Methyl methacrylate was purified three times by distillation under reduced pressure. Potassium persulfate was recrystallized twice from water and then dried under vacuum. Sodium chloride and sodium sulfate were all analytical grade materials and were used without further purification. Distilled and deionized water was used throughout the experiments. P M M A latex was prepared in the absence of emulsifier. The polymerization of 60-g methyl methacrylate in 240-ml deionized water was initiated with 0.08-g potassium persulfate. The reaction was carried out in nitrogen atmosphere at 70°C for 4 hr. This latex was purified by the procedure described in previous paper (7). The average diameter of latex particles was 0.454 #m by electron microscopy. Fabrics of polyamide Nylon (Toyobo Comp., Ltd.), polyester Tetoron (Toray Comp., Ltd.), and polyacrylonitrile Vonnel (Mitsubishi Rayon Comp., Ltd.) were used as fibers. These fabrics were purified by the procedures described previously (7).
Methods Five-grams weighed fabric (1 × 2 cm) was immersed in a 200-ml latex dispersion (0.1 g/liter solid content) adjusted to the required concentration of electrolytes. About 3.5-ml dispersion was withdrawn at regular time intervals and the amount of latex deposited on fiber was determined as a function of time by means of turbidity measurement. Turbidity measurements were performed at a wavelength of 540 nm by using a Hitachi 100-10 type spectrophotometer. From this, the rate of deposition was determined. ~" potentials of latex particles and fibers were measured by the methods of micro-
electrophoresis and streaming potential, respectively (7). For both ~"potential and turbidity measurements, the pH was 5.7. The interaction energy between fibers and latex particles was determined by application of heterocoagulation theory for spheres and plates (2). The interaction energy of electrical double layers (IRE) was calculated by the equation ae I" 2
VE = 4 ~ L(Ipl"~ ~2) 71-
lneXp(2KH)-- 1 exp(2rH)
2~11~2In exp(KH) --
,
[ 1]
where a is the radius of a latex particle, ~ is the dielectric constant of the medium, k is the Boltzmann constant, T is the absolute temperature, H is the distance between a latex particle and fiber, x is the DebyeHiickel parameter, and ¢1 and ¢2 are surface potentials of a latex particle and fiber, respectively. In this study, ~" potentials were used as surface potentials. The interaction energy of van der Waals forces (VA) was calculated by the equation
(lO)
A12/3 VA
=
--
6kT
V2a(H + a)
LH---~+--2a) -In----~],
[2]
where A12/3 is the Hamaker constant between PMMA and fiber in water. The value of A12/3 was calculated by
A12/3 = (A11/3"A22/3) 1/2,
[3]
where A11/3 and A22/3 are the Hamaker constants for P M M A and fiber in water, respectively. The value of A11/3 used was 4.0 × 10-13 erg (11). The value of A22/3 was calculated from the contact angles with water by the method described by Fowkes (6, 12). From those results, the values of A22/3 used for Nylon, Vonnel, and Tetoron were 4.1 × 10-13, 6.1 × 10-13, and 3.6 × 10-13 ergs, respectively. Journal o f Colloid and Interface Science, VoL 88, No. 2, August 1982
374
TAMAI AND SUZAWA
The total interaction energy (VT) was calculated by the summation of VE and IrA.
60
RESULTS AND DISCUSSION Potential
~" potentials of latex particles and three kinds of fabrics are shown in Figs. 1 and 2 as a function of ionic strength by sodium chloride and sodium sulfate at pH 5.7, respectively. The negative values of ~" potentials of latex particles and fabrics decrease linearly with increasing the concentration of electrolytes, and those in sodium sulfate solutions are slightly higher than those in sodium chloride ones at the same ionic strength. The negative values of ~ potentials of three kinds of fabrics decrease in the order of Tetoron fabric, Nylon fabric, and Vonnel fabric at the same concentration of electrolytes. R a t e o f Deposition
The amounts of latex deposited on Nylon fabric, Vonnel fabric, and Tetoron fabric are shown in Figs. 3, 4, and 5, respectively, as a function of time and the concentration of sodium sulfate at pH 5.7. For the three kinds of fabrics, the amounts of latex deposited all increase with increasing concentration of sodium sulfate. Though the amounts deposited decrease in the order of Vonnel fabric, Nylon fabric, and Tetoron fabric at the same concentration of sodium sulfate, those on Vonnel fabric increase remarkably at the initial stage of deposition. The deposition in sodium
2o 0
-3
-2
Log l
'
-1
FIG. 2. ~" potential of fabrics as a function of ionic strength of electrolytes at pH 5.7 and 25°C. O: Nylon fabric in NaCI; O: Nylon fabric in Na2SO4; A: Tetoron fabric in NaCI; A: Tetoron fabric in Na2SO4; n: Vonnel fabric in NaCI; I1: Vonnel fabric in Na2SO4.
chloride solutions exhibited the same tendency as that in sodium sulfate solutions shown in Figs. 3, 4, and 5, with respect to the change of the concentration of electrolyte. Since the turbidity of latex dispersions without fabrics was constant for the passage of time, latex particles were stable for homocoagulation in the range of the concentration of electrolytes used, and it was expected that latex particles deposit individually on fabrics. According to Boughey et al. (13), it was assumed that the rate of deposition is dCt dt = kc[Co - Ct][1 -
otl]
- kECt,
[4]
-O.8
o 0.6 o 0.4 t &
8°f I
'2b Log I
FIG. 1. ~" potential of latex as a function of ionic strength of electrolytes at pH 5.7 and 25°C. O: NaC1; O: Na2SO4. Journal of Colloid and Interface Science, Vol. 88, No. 2, August 1982
'4b
'
Time(min.)
' 8b
'
FIG. 3. Deposition of latex on Nylon fabric as a function of time and concentration of NazSO4 at pH 5.7 and 25°C. O: 0.3 X 10 -9 M; A: 0.7 X 10 -3 M; n: 1.0 X 10 -3 M; O: 1.4 X 10 -3 M; A: 2.0 X 10 -9 M; I : 3.0 X 10 -3 M; 0~: 7.0 X 10 -3 M.
DEPOSITION OF LATEX ON FIBERS 1.5
375
d i s p e r s i o n is v e r y d i l u t e a n d t h e s u r f a c e a r e a of f a b r i c is large. T h e r e f o r e , t h e r a t e o f deposition is e x p r e s s e d b y
~I.0
,
,
~
dCt - -
"~-o
dt
=
ko[Co
-
ct]
[5]
a n d i n t e g r a t i o n o f Eq. [5] gives kot = In [Co/(Co - C,)].
_J
20
40 60 Time(min.)
80
FIG. 4. Deposition of latex on Vonnel fabric as a function of time and concentration of Na2SO4 at pH 5.7 and 25°C. O: 0.3 × 10 .3 M; A: 0.4 × 10 .3 M; n: 0.6 × 10.3 M; 0:1.0 X 10.3 M; A: 3.0 X 10.3 M.
w h e r e Co is t h e initial c o n c e n t r a t i o n of l a t e x p a r t i c l e s , Ct is t h e a m o u n t o f l a t e x p a r t i c l e s d e p o s i t e d at t i m e t, a n d kc, kE a r e r a t e constants for p a r t i c l e c a p t u r e b y t h e f a b r i c a n d t h e i r e s c a p e f r o m it, respectively; 0 t is t h e f r a c t i o n a l s u r f a c e c o v e r a g e of f a b r i c at t i m e t. In o u r e x p e r i m e n t s , kE is p r o b a b l y z e r o since t h e d e p o s i t i o n e x p e r i m e n t s w e r e c a r ried o u t on s t a n d i n g w i t h o u t s t i r r i n g or rot a t i n g . I n a d d i t i o n , 0t is v e r y s m a l l t h r o u g h out the deposition time because the latex
[6]
F r o m Eq. [6], t h e r a t e c o n s t a n t s of d e p o s i tion were d e t e r m i n e d as a f u n c t i o n o f t h e c o n c e n t r a t i o n o f e l e c t r o l y t e s . In this d e t e r m i n a t i o n , the l a t e x c o n c e n t r a t i o n at 10 m i n a f t e r i m m e r s i n g f a b r i c s in l a t e x d i s p e r s i o n s was t a k e n as t h e initial c o n c e n t r a t i o n to e l i m i n a t e t h e e r r o r in t h e initial m i x i n g o f f a b r i c w i t h l a t e x dispersions. The rate constants of deposition obtained a r e shown in Fig. 6 as a f u n c t i o n o f ionic strength generated by sodium chloride and s o d i u m s u l f a t e at p H 5.7. T h e r a t e s o f deposition on t h e t h r e e kinds o f f a b r i c s all inc r e a s e with i n c r e a s i n g t h e c o n c e n t r a t i o n of e l e c t r o l y t e s a n d t e n d to b e c o m e c o n s t a n t above a certain concentration of electrolytes. T h e c o n c e n t r a t i o n of electrolytes above which
~<3 0.8 ~-
It:
0.6
k,7,~ oJ3
c~_ 0.4 •
0o
I
"13 o'~
0 20 FIG. 5. Deposition function of time and 5.7 and 25°C. O: 0.3 2.0 X 10.3 M; O: 3.0
4O 60 Time(rain.)
80
of latex on Tetoron fabric as a concentration of Na2SO4 at pH × 10-3 M; ZX: 1.0 × 10 -3 M ; El: × 10 3 M; A: 8.0 X 10.3 M.
-3
-2 Log I
FIG. 6. Rate constants of deposition of latex on fabrics as a function of ionic strength of electrolytes at pH 5.7 and 25°C. O: Nylon fabric in NaC1; O: Nylon fabric in N a 2 S O 4 ; A: Tetoron fabric in NaCI; A: Tetoron fabric in Na2SO4; el: Vonnel fabric in NaC1; I1: Vonnel fabric in Na2SO4. Journal o f Colloid and Interface Science, Vol. 88, No. 2, August 1982
376
TAMAI AND SUZAWA
the rates of deposition become constant decreases in the order of Tetoron fabric, Nylon fabric, and Vonnel fabric. At the same ionic strength, the rate constants of deposition decrease in the order of Vonnel fabric, Nylon fabric, and Tetoron fabric. The rates of deposition in sodium chloride solutions are slightly higher than those in sodium sulfate ones at the same ionic strength.
o3
a
7r:
E2
o
ro
u1
Total Interaction Energy The total interaction energy (VT) between latex particles and Nylon fabric is illustrated in Fig. 7 as a function of distance and the concentration of sodium sulfate at pH 5.7. The value of VT between latex particles and Nylon fabric decreases with increasing concentration of sodium sulfate. Though VT between Tetoron fabric and latex particles and VT between Vonnel fabric and latex particles are not shown in this report, these VT exhibited the same tendency as that between Nylon fabric and latex particles with respect to the change of the concentration of electrolytes. Accordingly, it is expected that la-
20O A
.-.100
>
16o H (A) 26o FIG. 7. Total interaction energy between latex particles and Nylon fabric as a function of distance ( H ) and concentration of Na2SO4 at pH 5.7 and 25°C. A: 0.3 X 10 -3 M; B: 0.7 X 10 -3 M; C: 1.0 X 10 -3 M; D: 1.4 × 10 -3 M; E: 2.0 × 10 -3 M; F: 3.0 × 10 -3 g . Journal of Colloid and Interface Science, VoL 88, No, 2, August 1982
0
0
100 2O0 3OO ZOO 5O0 Vr~.a~ ( k T )
FIG. 8. Relation between rate constants of deposition and Vrm~. ©: Nylon fabric in NaC1; O: Nylon fabric in Na2SO4; A: Tetoron fabric in NaCI, A: Tetoron fabric in Na2SO4; 12: Vonnel fabric in NaC1; n: Vonnel fabric in Na:SO4.
tex particles become deposited rapidly, that is to say, the rate of deposition increases with increasing concentration of electrolytes. The values of Vr between latex particles and fabric possess maxima (VTmax) at a certain distance in all solutions of electrolytes, and decrease when both substances approach closer.
Relation between Rates of Deposition and Interaction Energy Since VTmax must significantly influence the rate of deposition, the relation between VTmax and the rate constants of deposition was considered. The results obtained are shown in Fig. 8. The rate constants of deposition on Vonnel fabric are constant below about 200kT of Vx maxand decrease with further increasing VT.... Those on Nylon fabric and Tetoron fabric decrease gradually with increasing VTmax and latex particles deposit up to about 500kT of VTmax- The rate constants of deposition on Vonnel fabric are larger than those on the other two fabrics when the values of VTmaxare the same. Marshall et al. (14) have studied the deposition of carbon black particles on solids by the
377
DEPOSITION OF LATEX ON FIBERS
rotating disk technique, and reported that the deposition is dependent only partly on the interaction energy of electrical double layers and van der Waals forces, but is also influenced by the surface roughness of solids. In our previous paper (7), it has been noted that the surface of Nylon and Tetoron is smoother than that of Vonnel, and that many grooves are present on the surface of Vonnel from observation with a scanning electron microscope. Therefore, the high deposition on Vonnel fabric may be attributed to the influence of the surface roughness of fiber. On the other hand, it is generally supposed that a repulsive energy of more than 15kT is necessary to prevent colloidal particles from coagulating (15). However, as shown in Fig. 8, latex particles deposit on Nylon and Tetoron fabrics in spite of the presence of V x m a x m o r e than 15kT. From the study of the deposition of polystyrene latex particles on smooth plastic films by rotating disk technique, Hull et al. (16) have reported that anomalous deposition may be correlated to some heterogeneity of potential. This heterogeneity of potential may cause the deposition of latex particles on Nylon and Tetoron fabric in spite of large Vx In our previous paper (8), on the deposition of P M M A latex on fabrics, the relation between the rate of deposition and the interaction energy has been studied as a function of pH at 10-3 constant ionic strength. Those results have suggested that the deposition of P M M A latex on Tetoron fabric and Nylon fabric is highly influenced by the change of Vx max as a function of pH. The deposition of P M M A latex on Tetoron and Nylon fabrics is similarly influenced by the change of Vxmax as a function of the con....
centration of electrolytes as shown in Fig. 8. However, V m a x a s a function of the concentration of electrolytes does not so highly influence the deposition as does Vx max as a function of pH. ACKNOWLEDGMENTS The authors wish to thank Toyobo Comp., Ltd., Toray Comp., and Mitsubishi Rayon Comp., Ltd. for providing the fabrics. REFERENCES 1. Derjaguin, B. V., Kolloid Z. 69, 155 (1934); Acta Physicochim. USSR 10, 333 (1939). 2. Hogg, R., Healy, T. W., and Fuerstenau, D. W., Trans. Faraday Soc. 62, 1638 (1966). 3. Barouch, E., Matijevi6, E., Ring, T. A., and Finlan, M., J. Colloid Interface Sci. 67, 1 (1978); 70, 29 (1979). 4. Sasaki, H., Matijevi6, E., and Barouch, E., J. Colloid Interface Sci. 76, 319 (1980). 5. Kuo, R. J., and Matijevi6, E., J. Colloid Interface Sci. 78, 407 (1980). 6. Suzawa, T., Tamai, H., Shirahama, H., and Yamamoto, K., Nippon Kagaku Kaishi 1979, 16 (1979). 7. Tamai, H., Hakozaki, T., and Suzawa, T., Colloid Polym. ScL 258, 870 (1980). 8. Tamai, H., and Suzawa, T., Colloid Polym. Sci. 259, 1100 (1981). 9. Imamura, T., and Tokiwa, F., Nippon Kagaku Kaishi 1972, 2177 (1972). 10. Kitahara, A., Kagaku no Ryoiki 24, 402 (1970). 11. Ono, H., and Saeki, H., Colloid Polym. ScL 253, 744 (1975). 12. Fowkes, F. M., Ind. Eng. Chem. 56, 40 (1964). 13. Boughey, M. T., Duckworth, R. M., Lips, A., and Smith, A. L., J. Chem. Soc. Faraday Trans. 1 74, 2200 (1978). 14. Marshall, J. K., and Kitchener, J. A., J. Colloid Interface Sci. 22, 342 (1966). 15. Verway, J. W., and Overbeek, J. Th. G., "Theory of the Stability of Lyophobic Colloids." Elsevier, Amsterdam, 1948. 16. Hull, M., and Kitchener, J. A., Trans. Faraday Soc. 65, 3093 (1969).
Journal o f Colloid and Interface Science, Vol. 88, No. 2, August 1982
A heterocoagulation theory has been proposed by Derjaguin (1), and Hogg, Healy, and Fuerstenau ( H H F ) (2). Recently, Barouch et al. (3) have determined the interaction energy of unequal spheres by employing the Poisson-Boltzmann equation in its two- dimensional form, and their theoretical results have been compared with experimental data (4, 5). Since the deposition of latex particles on fibers is assumed to be a heterocoagulation between fibers and latex particles, the deposition is probably influenced by the interaction energy of electrical double layers and van der Waals forces between both substances. Thus, the theoretical interpretation of latex deposition may be aid by application of heterocoagulation theory. This paper is Part IV in a series "Interfacial electrical studies on the deposition of polymer latexes onto fabrics and the removal of these deposited latexes"; Part III: H. Tamai and T. Suzawa, Colloid Polym. Sci., 259, l l 0 0 (1981).
From these points of view, on the deposition of anionic polystyrene latex and polymethyl methacrylate ( P M M A ) latex on fibers, the change of the interaction energy between fibers and latex particles as a function of pH has been estimated using the H H F approximate solution for the interaction of dissimilar materials (6, 7). In addition, the relation between their interaction energy and the amount deposited of latex, the rate of deposition and the state of latex particles deposited on fibers have been considered (6-8). Further, it is important that the effects of the kind and the concentration of electrolytes on the deposition are considered, because the stability of latex is remarkably influenced by those factors. In this paper, on the deposition of anionic P M M A latex on fibers, the relation between the rate of deposition and the interaction energy as a function of electrolyte concentration is reported. Sodium chloride and sodium sulfate were used as electrolytes, and 372
0021-9797/82/080372-0652.00/0 Copyright© 1982 by AcademicPress, Inc, All rightsof reproductionin any form reserved.
Journalof ColloidandInterfaceScience,Vol. 88, No. 2, August 1982
373
DEPOSITION OF LATEX ON FIBERS
the interaction energy was estimated by heterocoagulation theory using the H H F approximation (1). EXPERIMENTAL
Materials Methyl methacrylate was purified three times by distillation under reduced pressure. Potassium persulfate was recrystallized twice from water and then dried under vacuum. Sodium chloride and sodium sulfate were all analytical grade materials and were used without further purification. Distilled and deionized water was used throughout the experiments. P M M A latex was prepared in the absence of emulsifier. The polymerization of 60-g methyl methacrylate in 240-ml deionized water was initiated with 0.08-g potassium persulfate. The reaction was carried out in nitrogen atmosphere at 70°C for 4 hr. This latex was purified by the procedure described in previous paper (7). The average diameter of latex particles was 0.454 #m by electron microscopy. Fabrics of polyamide Nylon (Toyobo Comp., Ltd.), polyester Tetoron (Toray Comp., Ltd.), and polyacrylonitrile Vonnel (Mitsubishi Rayon Comp., Ltd.) were used as fibers. These fabrics were purified by the procedures described previously (7).
Methods Five-grams weighed fabric (1 × 2 cm) was immersed in a 200-ml latex dispersion (0.1 g/liter solid content) adjusted to the required concentration of electrolytes. About 3.5-ml dispersion was withdrawn at regular time intervals and the amount of latex deposited on fiber was determined as a function of time by means of turbidity measurement. Turbidity measurements were performed at a wavelength of 540 nm by using a Hitachi 100-10 type spectrophotometer. From this, the rate of deposition was determined. ~" potentials of latex particles and fibers were measured by the methods of micro-
electrophoresis and streaming potential, respectively (7). For both ~"potential and turbidity measurements, the pH was 5.7. The interaction energy between fibers and latex particles was determined by application of heterocoagulation theory for spheres and plates (2). The interaction energy of electrical double layers (IRE) was calculated by the equation ae I" 2
VE = 4 ~ L(Ipl"~ ~2) 71-
lneXp(2KH)-- 1 exp(2rH)
2~11~2In exp(KH) --
,
[ 1]
where a is the radius of a latex particle, ~ is the dielectric constant of the medium, k is the Boltzmann constant, T is the absolute temperature, H is the distance between a latex particle and fiber, x is the DebyeHiickel parameter, and ¢1 and ¢2 are surface potentials of a latex particle and fiber, respectively. In this study, ~" potentials were used as surface potentials. The interaction energy of van der Waals forces (VA) was calculated by the equation
(lO)
A12/3 VA
=
--
6kT
V2a(H + a)
LH---~+--2a) -In----~],
[2]
where A12/3 is the Hamaker constant between PMMA and fiber in water. The value of A12/3 was calculated by
A12/3 = (A11/3"A22/3) 1/2,
[3]
where A11/3 and A22/3 are the Hamaker constants for P M M A and fiber in water, respectively. The value of A11/3 used was 4.0 × 10-13 erg (11). The value of A22/3 was calculated from the contact angles with water by the method described by Fowkes (6, 12). From those results, the values of A22/3 used for Nylon, Vonnel, and Tetoron were 4.1 × 10-13, 6.1 × 10-13, and 3.6 × 10-13 ergs, respectively. Journal o f Colloid and Interface Science, VoL 88, No. 2, August 1982
374
TAMAI AND SUZAWA
The total interaction energy (VT) was calculated by the summation of VE and IrA.
60
RESULTS AND DISCUSSION Potential
~" potentials of latex particles and three kinds of fabrics are shown in Figs. 1 and 2 as a function of ionic strength by sodium chloride and sodium sulfate at pH 5.7, respectively. The negative values of ~" potentials of latex particles and fabrics decrease linearly with increasing the concentration of electrolytes, and those in sodium sulfate solutions are slightly higher than those in sodium chloride ones at the same ionic strength. The negative values of ~ potentials of three kinds of fabrics decrease in the order of Tetoron fabric, Nylon fabric, and Vonnel fabric at the same concentration of electrolytes. R a t e o f Deposition
The amounts of latex deposited on Nylon fabric, Vonnel fabric, and Tetoron fabric are shown in Figs. 3, 4, and 5, respectively, as a function of time and the concentration of sodium sulfate at pH 5.7. For the three kinds of fabrics, the amounts of latex deposited all increase with increasing concentration of sodium sulfate. Though the amounts deposited decrease in the order of Vonnel fabric, Nylon fabric, and Tetoron fabric at the same concentration of sodium sulfate, those on Vonnel fabric increase remarkably at the initial stage of deposition. The deposition in sodium
2o 0
-3
-2
Log l
'
-1
FIG. 2. ~" potential of fabrics as a function of ionic strength of electrolytes at pH 5.7 and 25°C. O: Nylon fabric in NaCI; O: Nylon fabric in Na2SO4; A: Tetoron fabric in NaCI; A: Tetoron fabric in Na2SO4; n: Vonnel fabric in NaCI; I1: Vonnel fabric in Na2SO4.
chloride solutions exhibited the same tendency as that in sodium sulfate solutions shown in Figs. 3, 4, and 5, with respect to the change of the concentration of electrolyte. Since the turbidity of latex dispersions without fabrics was constant for the passage of time, latex particles were stable for homocoagulation in the range of the concentration of electrolytes used, and it was expected that latex particles deposit individually on fabrics. According to Boughey et al. (13), it was assumed that the rate of deposition is dCt dt = kc[Co - Ct][1 -
otl]
- kECt,
[4]
-O.8
o 0.6 o 0.4 t &
8°f I
'2b Log I
FIG. 1. ~" potential of latex as a function of ionic strength of electrolytes at pH 5.7 and 25°C. O: NaC1; O: Na2SO4. Journal of Colloid and Interface Science, Vol. 88, No. 2, August 1982
'4b
'
Time(min.)
' 8b
'
FIG. 3. Deposition of latex on Nylon fabric as a function of time and concentration of NazSO4 at pH 5.7 and 25°C. O: 0.3 X 10 -9 M; A: 0.7 X 10 -3 M; n: 1.0 X 10 -3 M; O: 1.4 X 10 -3 M; A: 2.0 X 10 -9 M; I : 3.0 X 10 -3 M; 0~: 7.0 X 10 -3 M.
DEPOSITION OF LATEX ON FIBERS 1.5
375
d i s p e r s i o n is v e r y d i l u t e a n d t h e s u r f a c e a r e a of f a b r i c is large. T h e r e f o r e , t h e r a t e o f deposition is e x p r e s s e d b y
~I.0
,
,
~
dCt - -
"~-o
dt
=
ko[Co
-
ct]
[5]
a n d i n t e g r a t i o n o f Eq. [5] gives kot = In [Co/(Co - C,)].
_J
20
40 60 Time(min.)
80
FIG. 4. Deposition of latex on Vonnel fabric as a function of time and concentration of Na2SO4 at pH 5.7 and 25°C. O: 0.3 × 10 .3 M; A: 0.4 × 10 .3 M; n: 0.6 × 10.3 M; 0:1.0 X 10.3 M; A: 3.0 X 10.3 M.
w h e r e Co is t h e initial c o n c e n t r a t i o n of l a t e x p a r t i c l e s , Ct is t h e a m o u n t o f l a t e x p a r t i c l e s d e p o s i t e d at t i m e t, a n d kc, kE a r e r a t e constants for p a r t i c l e c a p t u r e b y t h e f a b r i c a n d t h e i r e s c a p e f r o m it, respectively; 0 t is t h e f r a c t i o n a l s u r f a c e c o v e r a g e of f a b r i c at t i m e t. In o u r e x p e r i m e n t s , kE is p r o b a b l y z e r o since t h e d e p o s i t i o n e x p e r i m e n t s w e r e c a r ried o u t on s t a n d i n g w i t h o u t s t i r r i n g or rot a t i n g . I n a d d i t i o n , 0t is v e r y s m a l l t h r o u g h out the deposition time because the latex
[6]
F r o m Eq. [6], t h e r a t e c o n s t a n t s of d e p o s i tion were d e t e r m i n e d as a f u n c t i o n o f t h e c o n c e n t r a t i o n o f e l e c t r o l y t e s . In this d e t e r m i n a t i o n , the l a t e x c o n c e n t r a t i o n at 10 m i n a f t e r i m m e r s i n g f a b r i c s in l a t e x d i s p e r s i o n s was t a k e n as t h e initial c o n c e n t r a t i o n to e l i m i n a t e t h e e r r o r in t h e initial m i x i n g o f f a b r i c w i t h l a t e x dispersions. The rate constants of deposition obtained a r e shown in Fig. 6 as a f u n c t i o n o f ionic strength generated by sodium chloride and s o d i u m s u l f a t e at p H 5.7. T h e r a t e s o f deposition on t h e t h r e e kinds o f f a b r i c s all inc r e a s e with i n c r e a s i n g t h e c o n c e n t r a t i o n of e l e c t r o l y t e s a n d t e n d to b e c o m e c o n s t a n t above a certain concentration of electrolytes. T h e c o n c e n t r a t i o n of electrolytes above which
~<3 0.8 ~-
It:
0.6
k,7,~ oJ3
c~_ 0.4 •
0o
I
"13 o'~
0 20 FIG. 5. Deposition function of time and 5.7 and 25°C. O: 0.3 2.0 X 10.3 M; O: 3.0
4O 60 Time(rain.)
80
of latex on Tetoron fabric as a concentration of Na2SO4 at pH × 10-3 M; ZX: 1.0 × 10 -3 M ; El: × 10 3 M; A: 8.0 X 10.3 M.
-3
-2 Log I
FIG. 6. Rate constants of deposition of latex on fabrics as a function of ionic strength of electrolytes at pH 5.7 and 25°C. O: Nylon fabric in NaC1; O: Nylon fabric in N a 2 S O 4 ; A: Tetoron fabric in NaCI; A: Tetoron fabric in Na2SO4; el: Vonnel fabric in NaC1; I1: Vonnel fabric in Na2SO4. Journal o f Colloid and Interface Science, Vol. 88, No. 2, August 1982
376
TAMAI AND SUZAWA
the rates of deposition become constant decreases in the order of Tetoron fabric, Nylon fabric, and Vonnel fabric. At the same ionic strength, the rate constants of deposition decrease in the order of Vonnel fabric, Nylon fabric, and Tetoron fabric. The rates of deposition in sodium chloride solutions are slightly higher than those in sodium sulfate ones at the same ionic strength.
o3
a
7r:
E2
o
ro
u1
Total Interaction Energy The total interaction energy (VT) between latex particles and Nylon fabric is illustrated in Fig. 7 as a function of distance and the concentration of sodium sulfate at pH 5.7. The value of VT between latex particles and Nylon fabric decreases with increasing concentration of sodium sulfate. Though VT between Tetoron fabric and latex particles and VT between Vonnel fabric and latex particles are not shown in this report, these VT exhibited the same tendency as that between Nylon fabric and latex particles with respect to the change of the concentration of electrolytes. Accordingly, it is expected that la-
20O A
.-.100
>
16o H (A) 26o FIG. 7. Total interaction energy between latex particles and Nylon fabric as a function of distance ( H ) and concentration of Na2SO4 at pH 5.7 and 25°C. A: 0.3 X 10 -3 M; B: 0.7 X 10 -3 M; C: 1.0 X 10 -3 M; D: 1.4 × 10 -3 M; E: 2.0 × 10 -3 M; F: 3.0 × 10 -3 g . Journal of Colloid and Interface Science, VoL 88, No, 2, August 1982
0
0
100 2O0 3OO ZOO 5O0 Vr~.a~ ( k T )
FIG. 8. Relation between rate constants of deposition and Vrm~. ©: Nylon fabric in NaC1; O: Nylon fabric in Na2SO4; A: Tetoron fabric in NaCI, A: Tetoron fabric in Na2SO4; 12: Vonnel fabric in NaC1; n: Vonnel fabric in Na:SO4.
tex particles become deposited rapidly, that is to say, the rate of deposition increases with increasing concentration of electrolytes. The values of Vr between latex particles and fabric possess maxima (VTmax) at a certain distance in all solutions of electrolytes, and decrease when both substances approach closer.
Relation between Rates of Deposition and Interaction Energy Since VTmax must significantly influence the rate of deposition, the relation between VTmax and the rate constants of deposition was considered. The results obtained are shown in Fig. 8. The rate constants of deposition on Vonnel fabric are constant below about 200kT of Vx maxand decrease with further increasing VT.... Those on Nylon fabric and Tetoron fabric decrease gradually with increasing VTmax and latex particles deposit up to about 500kT of VTmax- The rate constants of deposition on Vonnel fabric are larger than those on the other two fabrics when the values of VTmaxare the same. Marshall et al. (14) have studied the deposition of carbon black particles on solids by the
377
DEPOSITION OF LATEX ON FIBERS
rotating disk technique, and reported that the deposition is dependent only partly on the interaction energy of electrical double layers and van der Waals forces, but is also influenced by the surface roughness of solids. In our previous paper (7), it has been noted that the surface of Nylon and Tetoron is smoother than that of Vonnel, and that many grooves are present on the surface of Vonnel from observation with a scanning electron microscope. Therefore, the high deposition on Vonnel fabric may be attributed to the influence of the surface roughness of fiber. On the other hand, it is generally supposed that a repulsive energy of more than 15kT is necessary to prevent colloidal particles from coagulating (15). However, as shown in Fig. 8, latex particles deposit on Nylon and Tetoron fabrics in spite of the presence of V x m a x m o r e than 15kT. From the study of the deposition of polystyrene latex particles on smooth plastic films by rotating disk technique, Hull et al. (16) have reported that anomalous deposition may be correlated to some heterogeneity of potential. This heterogeneity of potential may cause the deposition of latex particles on Nylon and Tetoron fabric in spite of large Vx In our previous paper (8), on the deposition of P M M A latex on fabrics, the relation between the rate of deposition and the interaction energy has been studied as a function of pH at 10-3 constant ionic strength. Those results have suggested that the deposition of P M M A latex on Tetoron fabric and Nylon fabric is highly influenced by the change of Vx max as a function of pH. The deposition of P M M A latex on Tetoron and Nylon fabrics is similarly influenced by the change of Vxmax as a function of the con....
centration of electrolytes as shown in Fig. 8. However, V m a x a s a function of the concentration of electrolytes does not so highly influence the deposition as does Vx max as a function of pH. ACKNOWLEDGMENTS The authors wish to thank Toyobo Comp., Ltd., Toray Comp., and Mitsubishi Rayon Comp., Ltd. for providing the fabrics. REFERENCES 1. Derjaguin, B. V., Kolloid Z. 69, 155 (1934); Acta Physicochim. USSR 10, 333 (1939). 2. Hogg, R., Healy, T. W., and Fuerstenau, D. W., Trans. Faraday Soc. 62, 1638 (1966). 3. Barouch, E., Matijevi6, E., Ring, T. A., and Finlan, M., J. Colloid Interface Sci. 67, 1 (1978); 70, 29 (1979). 4. Sasaki, H., Matijevi6, E., and Barouch, E., J. Colloid Interface Sci. 76, 319 (1980). 5. Kuo, R. J., and Matijevi6, E., J. Colloid Interface Sci. 78, 407 (1980). 6. Suzawa, T., Tamai, H., Shirahama, H., and Yamamoto, K., Nippon Kagaku Kaishi 1979, 16 (1979). 7. Tamai, H., Hakozaki, T., and Suzawa, T., Colloid Polym. ScL 258, 870 (1980). 8. Tamai, H., and Suzawa, T., Colloid Polym. Sci. 259, 1100 (1981). 9. Imamura, T., and Tokiwa, F., Nippon Kagaku Kaishi 1972, 2177 (1972). 10. Kitahara, A., Kagaku no Ryoiki 24, 402 (1970). 11. Ono, H., and Saeki, H., Colloid Polym. ScL 253, 744 (1975). 12. Fowkes, F. M., Ind. Eng. Chem. 56, 40 (1964). 13. Boughey, M. T., Duckworth, R. M., Lips, A., and Smith, A. L., J. Chem. Soc. Faraday Trans. 1 74, 2200 (1978). 14. Marshall, J. K., and Kitchener, J. A., J. Colloid Interface Sci. 22, 342 (1966). 15. Verway, J. W., and Overbeek, J. Th. G., "Theory of the Stability of Lyophobic Colloids." Elsevier, Amsterdam, 1948. 16. Hull, M., and Kitchener, J. A., Trans. Faraday Soc. 65, 3093 (1969).
Journal o f Colloid and Interface Science, Vol. 88, No. 2, August 1982