Dyeing Kinetics and Colouristic Properties of Blend PP/PES Fibres

n Introduction 

E. Bolhová, 

Anna Ujhelyiová, 

K. Vaľková, 

Anton Marcinčin 

Slovak University of Technology in Bratislava, 

Faculty of Chemical and Food Technology 

Institute of Polymer Materials, 

Department of Fibres and Textile Chemistry, 

Radlinského 9, 812 37 Bratislava, Slovak Republic, 

e-mail: eva.bolhova@stuba.sk 

Polypropylene (PP) is a very important 

polymer for the production of synthetic 

fibres due to its good physical and 

chemical properties as well as relatively 

low price. Recently, a lot of research has 

dealt with the modification of PP for engineering 

applications and improvement 

of some properties. The improvement 

of the dyeability of PP fibres bath-dyed 

belongs among these properties. 

One of these modifications, which improves 

some properties and dyeability 

of PP, is the preparation of fibre-forming 

polymer blends [1 - 7]. A polymer blend, 

which can increase the affinity of PP to 

disperse dyes, is blending PP with dif- 

FIBRES & TEXTILES in Eastern Europe January / December 2007, Vol. 15, No. 5 - 6 (64 - 65) 

Dyeing Kinetics and Colouristic Properties 

of Blend PP/PES Fibres 

Abstract 

The aim of this work was the study of the dyeability of blended polypropylene/polyester 

(PP/PES) fibres. Blended PP/PES fibres contain various polyesters - polyethylene 

terephthalate (PET), polybuthylene terephthalate (PBT), polytrimethylene terephthalate 

(PTT) and a blend of these polyesters. The fibres were dyed with C.I. Disperse Blue 79 

and C.I. Disperse Violet 95 at 98°C. The dyeing kinetics and colouristic properties of these 

fibres were investigated. In addition, the influence of different contents of individual PES 

was also studied. 

Key words: blend PP/PES fibres, disperse dye, dyeing kinetics. 

ferent polyesters (PES) [8, 9]. Apart from 

an improvement in dyeabilty, the blend 

of these polymers attains higher sorption 

properties and higher elasticity [2]. 

Polypropylene and polyester are thermodynamically 

immiscible, and therefore 

blending two or more polymers 

usually results in a multiphase blend, 

instead of homogenous materials. The 

formation of fibrillar phase morphology 

is affected by the compatibility of the 

polymer blendand technological process 

of preparation, i.e. blending history, 

blend ratio, viscosity of individual polymer 

compound and share rate. Hence, 

many researchers have focused on the 

control of morphology and interfaces of 

immiscible polymer blends in order to 

improve their compatibility. Bataile et al. 

[10] reported that PP/PET blends without 

compatibilisers exhibit weak interactions 

between the two phases and the mechanical 

properties showed lower values than 

individual PP and PET. The option of 

mixing and spinning conditions as well 

as the addition of suitable compatibilizers 

can increase uniformity in blend 

phase morphology and evenness of fibre 

properties at a lower viscosity of the PET 

dispersed in the PP matrix [11, 12] 

The morphology of the blended PP/PES 

fibres influences the dyeability of these 

fibres. Whereupon for the dyeing process 

of these fibres it is important to provide a 

uniform distribution of the PES particles 

in the PP matrix because the molecules 

of the disperse dye penetrate through 

the full cross section of blended PP/PES 

fibres, but the molecules of the dye are 

mainly localised in the PES particles. 

The uniform size and distribution of 

the PES particles in the PP matrix form 

a higher specific surface for the adsorption 

of disperse dyes from dyebath into 

fibres [9]. 

The transport of disperse dyes in PP/PES 

fibres from a bath can be described in 

four stages as follows: 

a) dissolution of the dye molecules from 

a dispersed state into a monomolecular 

dissolved state; 

b) transport through a bulk solution to 

near the surface; 

c) diffusional transport through any 

boundary layer surrounding the fibres 

and partition to the immediate surface 

of the fibre; 

d) diffusion within the fibre. 

In a well-optimised dyebath, the last step 

is rate-determinion . Most dye diffusion 

studies so far have usually determined the 

overall rate of dyeing. In these studies the 

diffusion coefficient is determined from 

the time-dependant dye-uptake [13 - 15]. 

The study of the dyeability of blended 

PP/PES fibres is the main aim of this paper. 

We prepared blend fibres containing 

different types of PES compounds (PET, 

PBT and PTT) and blends of PES compounds 

(PET/PBT, PET/PTT, PBT/PTT 

and PET/PBT/PTT). For the dyeing of 

blended PP/PES fibres, Disperse Blue 79 

and Disperse Violet 95 were used. The 

composition of dyebath was used as for 

PET fibres. We focused on the influence 

of the individual type of PES and its 

ability to increase the affinity of blended 

PP/PES fibres to disperse dyes. The influence 

of PES additives dispersed into a PP 

matrix on the dyeability and diffusion of 

disperse dyes are presented. 

n Experimental 

Synthetic fibres 

The following polymers were used for 

the preparation of the blended PP/PES 

fibres: 

n Polypropylene Tatren TG 920 (PP), 

Slovnaft, a.s., Bratislava, 

MFI = 10.5 g/10 min ; 

131

Table 1. Composition of the blend PP/PES fibres. 

n Polyethylene terephthalate PET 

(PET), Slovenský Hodváb, a. s., 

Senica, IV = 0.5 l.g-1 ; 

n Polybuthylene Terephthalate Celanex 

N 2000 (PBT), Ticona Engineering 

Polymer, MFI =19.8 g/10 min; 

n Poly(trimethylene terephthalate) 

(PTT) - Du Pont Co - η(γ =100 s-1) = 

260 Pa.s; 

n Licowax E (LiE) – polyester (montane) 

wax, Ciba Specialty Ltd. 

The blended PP/PES fibres was prepared 

in two steps - preparation of the 

PES concentrates and preparation of the 

blended PP/PES fibres. The composition 

of blended PP/PES fibres is in Table 1. 

Disperse dyes 

n C.I. Disperse Blue 79 

n C.I. Disperse Violet 95 

Dyeing 

Dyeing conditions 

In order to remove the lubricants, the 

fibres were washed in a bath of 1.5 g.l-1 

Slovapon and 1 g.l-1 Na3PO4 at 75°C for 

20 min. 

The fibres were dyed using a laboratory 

dyeing machine - Ahiba ↑↓ AG CH 4127 

Birsfelden (Switzerland). The following 

bath composition was used: dispersant 1 

g.l -1 Kortamol NNO, 2 g.l -1 (NH4)2SO4, 

132 

Types of fibres 

Contents of individual compound in the blended PP/PES fibres, % 

PP TG 920 PET PBT PTT Licowax E 

PET A - 100 - - 0.12 

PP/PET B 94.34 5.54 0.12 

PP/PBT C 94.34 5.54 0.12 

PP/PTT D 94.34 5.54 0.12 

PP/PET/PBT E 94.36 1.64 3.88 0.12 

PP/PET/PTT F 94.36 1.64 3.88 0.12 

PP/PBT/PTT G 94.36 3.88 1.64 0.12 

PP/PET/PBT/PTT H 94.40 1.88 1.8 1.8 0.12 

a) b) 

Figure 1. The dependencies of K/S on the type of blended PP/PES fibres dyed with Disperse 

Blue 79 (a) and Disperse Violet 95 (b) at 98 °C. Remark: A, ... H as in Table 1. 

0.17 g.l-1 Texavin and disperse dye 

1% o.w.f. The fibres were dyed at 98°C. 

Reduction clearing 

The dyed fibres were washed in a solution 

consisting 3 ml.l-1 NaOH 38°Be, 

1.5 g.l -1 Slovapon and 2 g.l -1 Na2S2O4, at 

75°C for 20 minutes. 

n Methods of analysis 

The kinetics of the disperse dyes exhaustion 

from bath into the PET and PP/PES 

fibres was evaluated upon an increase 

(decrease) of dye concentration in the 

fibres (in bath) during the dyeing process. 

The dyeing process of the? blended 

PP/PES fibres was finished at time intervals 

3, 5, 10, 15, 20, 25, 30, 50, 70 

and 90 min. The quantity of exhausted 

dye on the fibre was estimated from the 

absorption of dye solution measured at 

its λ max and from the calibration curve. 

The dependence of the exhaustion of dye 

on time was used for the calculation of 

the dyeing rate constant (K) and diffusion 

coefficient (D). The dyeing rate was determined 

from Vickerstaff’s hyperbolic 

equation [16, 17] (1): 

c t = K . t . c ∞ 2/(K . t . c ∞ + 1) (1) 

Diffusion coefficients D were obtained 

from Hill’s empirical equation [13, 18, 

19]. The principle of calculation for the 

apparent diffusion coefficient from Hill’s 

equation is the assumption of the identity 

of the half-dyeing time t1/2 (t1/2 is the 

time required for a fibre absorbing half 

the quantity of dye absorbed in a state of 

equilibrium) and half-time diffusion. The 

diffusion coefficient was calculated from 

the equation (2): 

D Hill = 6.324×10-2. K . c∞ . r2 (2) 

where: 

r - radius of fibre, m 

D - diffusion coefficient, m2. s-1 

K - dyeing rate constant from Vickerstaff’s 

equation, s -1 

ct - concentration of dye in fibre in the 

time t, mg . g-1 

c ∝ - concentration of dye at the moment 

of state of equilibrium (mg . g-1). 

n Results and discussion 

Dyeability of blended PP/PES fibres 

The blended PP/PES fibres, which contained 

5.54 wt. % of PET, PBT, PTT 

and blends of these polyesters, were 

dyed from bath at a temperature of 

98 °C with C.I. Disperse Blue 79 and 

C.I. Disperse Violet 95. The dyeability 

of the blended PP/PES fibres was 

evaluated on the basis of colour strength 

(K/S). The dependences of K/S on the 

composition of the blended PP/PES 

fibres are shown in the Figure 1 a-b. 

The results show that the affinity of disperse 

dyes to the blended PP/PES fibres 

is affected by the content and type of PES 

additive dispersed in the PP matrix. 

The highest value of K/S was reached in 

the blended PP/PES fibres, which contained 

5.54 wt.% of PET and was dyed 

with C.I. Disperse Blue 79. The K/S of 

the blended PP/PBT/LiE and PP/PTT/ 

LiE fibres reached about 23 - 25% lower 

values of K/S than PET fibres. PET and 

PTT dispersed in the PP matrix appeared 

to be an optimal blend of polyesters 

(Figure 1.a, blended PP/PET/PTT/LiE 

fibre). The value of K/S for this fibre 

reached similar K/S to that of the PET 

and PP/PET/LiE fibres and the K/S 

was about 20% higher than the K/S of 

blended PP/PTT/LiE fibre. The positive 

influence of PTT on the dyeability of 

blended PP/PET/PTT fibre can be caused 

by the suppression of crystallinity and an 

increase in their deformation ability in 

comparison with PET and PBT. It can 

improve the sorption of dye into blended 

PP/PES fibres. The K/S of the blended 

PP/PBT/PTT and PP/PET/PBT/PTT fibres 

were comparable with the K/S of the 

FIBRES & TEXTILES in Eastern Europe January / December 2007, Vol. 15, No. 5 - 6 (64 - 65)

lended fibres which contained 5.34 wt% 

of PBT or PTT. 

When dyeing with C.I. Disperse Violet 

95, the highest K/S was also measured 

for the blended PP/PET/LiE fibre. Actually, 

the K/S of these blended PP/PES 

fibres had a higher value than the K/S of 

PET fibre. Blended PP/PES (PP/PTT/LiE 

and PP/PET/PTT/LiE) fibres, which contain 

PTT compound have higher affinity 

to C.I. Disperse Violet 95 than blended 

PP/PBT/LiE and PP/PET/PBT/LiE fibres. 

On the other hand, a blend using all of 

PESs (PET, PBT and PTT) creates a suitable 

homogeneous phase, which is dispersed 

in the PP matrix as PES particles, 

for the fixation of Disperse Violet 95. 

There were reduction cleaning (RC) decreases 

of K/S in all investigated blend 

PP/PES fibres. The lower loss of dye 

after reduction cleaning was reached 

a) b) 

d) e) 

g) h) 


using C.I. Disperse Blue 79 for all the 

blended PP/PES fibres than using C.I 

Disperse Violet 95. The blended PP/PES 

fibres, which contained PET and a blend 

of PET/PBT/PTT, provide better fixation 

of disperse dye than other blended 

PP/PES fibres. The mutual effects of the 

PET/PBT/PTT blend was observed on 

the dyeability of these fibres. 

Kinetics of dyeing process of blended 

PP/PES fibres 

The dependencies of dye uptake (in 

mg . g-1) on the dyeing time for C.I. Disperse 

Blue 79 and C.I. Disperse Violet 95 

are shown at the Figures 2 and 3. The 

amount of exhausted dye for both dyes is 

increased with dyeing time. The dependencies 

of dye uptake confirm previous 

results. The amounts of exhausted dye 

in blended PP/PES fibres depend on the 

composition of these fibres. 

Results obtained from dyeing PET and 

blended PP/PES fibres with C.I. Disperse 

Blue 79 show that the temperature of 

98 °C is not satisfactory for the ideal 

colouring of PET fibre (Figure 2.a). All 

the blended fibres attained a higher 

dye uptake than PET fibre (Figure 2). 

It means that this dyeing temperature is 

not sufficient for the achievement of an 

equilibrium state in the dyeing of PET 

fibres. The influence of the individual 

type of polyester on the dyeability of 

blended fibres is shown in Figure 2. 

The highest amount of the exhausted 

dye from bath was reached in the fibres 

which contained 5.54 wt. % of PET and 

blend of PET/PTT (1.64/3.88) and the 

lowest in the blended PP/PBT fibre. 

The amount of the exhausted dye on 

the fibres is about 3 mg . g -1. The dyeability 

of blended PP/PES fibres containing 

two types of polyesters (PET/PBT 

c) 

f) 

Figure 2. The amount of exhausted 

dye c in [mg.g -1] C.I. Disperse Blue 

79 at 98°C for PET (a), blended PP/ 

PET (b), PP/PBT (c), PP/PTT (d), 

PP/PET/PBT (e), PP/PET/PTT (f), 

PP/PBT/PTT (g) and PP/PET/PBT/ 

PTT (h) fibres. 

133

or PET/PTT) is affected by the dominant 

PES component. 

Using the dye C. I. Disperse Violet 

95, the amount of exhausted dye for 

blended PP/PES is within the range up to 

2 mg . g-1 (Figure 3). The Blended PP/PET 

and PP/PTT fibres attained the highest 

dye uptake of all the fibres. Lower 

dye uptake of C.I. Disperse Violet 95, in 

comparison with C.I. Disperse Blue 79, 

can be evoked by a different molecular 

structure of dye as well as size of the 

particles. 

The dyeing process of blended PP/PES 

fibres using both disperse dyes can be 

described by the following steps - disperse 

dye is absorbed from bath on the 

surface of blended PP/PES fibres, then 

the dye penetrates from the surface into 

the blended fibres, where the disperse 

134 

dye is mainly absorbed by dispersed 

PES particles and interphase of PP and 

PES. For the description of the dyeing 

process of blended PP/PES fibres from 

bath, the Viskerstaff′s and Hill′s models 

were used. Calculated and experimental 

results are in the Figures 2 and 3 and in 

Table 2 (see page 140). From the dependencies 

(Figures 2 and 3) it is possible to 

observe, that both models (Vickerstaff 

and Hill) are suitable for evaluation 

of the kinetic process. In both circumstances 

calculated curves partially copy 

experimental points. These models were 

used for the evaluation of rate constant 

(K) and diffusion coefficient (D) for PET 

and PP/PES fibres coloured at 98 °C. The 

highest value of diffusion coefficient was 

reached for the blended PP/PTT/LiE and 

PP/PET/PTT/LiE fibres dyed with C.I. 

Disperse Blue 79 and for the blended 

PP/PBT/LiE and PP/PET/PBT/LiE fibres 

a) b) 

d) e) 

g) h) 

dyed with C.I. Disperse Violet 95. This is 

caused by the polymer chain of PTT and 

PBT because these chains are more flexible 

than that of PET. The diffusion of 

dye molecules into the dispersed particles 

of PTT or PBT in the PP matrix of blended 

fibres could be faster than into PET 

particles but fixation of disperse dyes is 

better in blended PP/PES fibres which 

a contain PET compound (Figure 1). 

The dyeing rate constants and diffusion 

coefficients define the rate of process 

dyeing but they do not characterise the 

quality exhaustion of dye on fibres and 

ability of individual fibres to dye. The 

exhaustion of dye’s very good ability as 

well as its fixation on the textile fibre 

or fabric depends on: affinity of dyes to 

fibres, concentration of dyes in bath, temperature 

and time of dyeing and textile 

auxiliaries. The results obtained confirm 

Figure 3. The amount of exhausted 

dye c in [mg.g-1] C.I. Disperse Violet 

95 at 98°C for PET (a), blended PP/ 

PET (b), PP/PBT (c), PP/PTT (d), 

PP/PET/PBT (e), PP/PET/PTT (f), 

PP/PBT/PTT (g) and PP/PET/PBT/ 

PTT (h) fibres. 


c) 

f)

Table 2. Diffusion coefficients (D) and dyeing rate constants (K) of blended PP/PES fibres 

dyed with C.I. Disperse Blue 79 and C.I. Disperse Violet 95. 

Blended PP/PES fibres 

that PP/PES fibres are sufficiently dyeable 

from bath by the classical method 

of using disperse dyes, but it is necessary 

to optimalise the dyeing condition of certain 

types of blended PP/PES fibres. 

n Conclusions 

On the basis of the results obtained, the 

following conclusions can be made: 

n the dyeability of all the blended fibres 

was excellent without streakiness; 

n the dyeability of blended PP/PES fibres 

is influenced by the type of PESs 

in blend fibres; 

n the highest K/S of dyed fibres was 

reached for the blended PP/PES fibre 

which contained 5.34 wt. % of PET 

dyed with both disperse dyes; 

n the dyeing kinetics of blend PP/PES 

fibres dyed with disperse dyes is possible, 

as described by the Viskerstaff’s 

and Hill’s model; 

n the highest value of diffusion coefficient 

was reached for the blended 

PP/PTT/LiE and PP/PET/PTT/LiE fibres 

dyed with C.I. Disperse Blue 79 

and for the blended PP/PBT/LiE and 

PP/PET/PBT/LiE fibres dyed with 

C.I. Disperse Violet 95. 

Acknowledgments 

C.I Disperse 

Blue 79 

Support of the National Grant Agency of Slovakia 

APVT -20-011404 and VEGA 1/4456/07 

is appreciated. 

References 


C.I Disperse 

Violet 95 

DHill . 10 14, m 2. s -1 KV . 10 4, s -1 DHill . 10 14, m 2. s -1 KV . 10 4, s -1 

PET A 4.93 3.8 1.06 1.1 

PP/PET/Li 

94.34/5.34/0.12 

PP/PBT/Li 

94.34/5.34/0.12 

PP/PTT/Li 

94.34/5.34/0.12 

PP/PET/PBT/Li 

94.36/1.64/3.88/0.12 

PP/PET/PTT/Li 

94.36/1.64/3.88/0.12 

PP/PBT/PTT/Li 

94.36/3.88/1.64/0.12 

PP/PET/PBT/PTT/Li 

94.36/1.88/1.8/1.8/0.12 

16.1 7.8 1.29 0.7 

7.06 4.7 2.30 2.7 

39.2 26.6 2.18 1.8 

5.84 3.5 2.36 2.5 

22.2 10.6 1.71 1.1 

8.44 4.9 2.00 1.8 

13.0 7.7 1.66 1.5 

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Received 15.11.2007 Reviewed 15.01.2008 

TZG 

Conference 

2008 

‘Textile Science 

and Economy’ 

26th January, 2008 

Organisers: 

n Faculty of Textile 

Technology, University 

of Zagreb 

n Croatian Academy 

of Sciences and Arts, 

the Scientific Council 

for Technological 

Development 

n Croatian Academy 

of Engineering 

The following topics 

are proposed: 

n A European technology 

platform for the future 

of textiles and clothing 

n The textile and clothing 

industry in the republic 

of Croatia – the present 

state and prospect for the 

future 

n New technologies 

& developments 

n Science & economy 

n Standarisation 

n Ecology 

n Intelligent clothing 

n Education 

For more information 

please contact: 

Tekstilno-tehnološki fakultet 

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Dyeing Kinetics and Colouristic Properties of Blend PP/PES Fibres

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