CC BY
7u(r) = ße-ar -
Q
(12)
(13)
где а, в, Q - константы. В дальнейшем положим, что параметр Q совпадает с соответствующим параметром потенциала Леннард-Джонса ^ = 4ваб), а параметры а и в находятся из системы уравнений
Ги(а) = ии(а)
Ца) = иь;(а)'
где а отвечает минимуму потенциала Леннард-Джонса Иы. Для декана нами были получены следующие результаты в = 3,84-105е, а = 11,5/а, Q = 4еа. Как видно из рис.1б (кривая 2), изотерма расклинивающего давления, отвечающая потенциалу (12), несколько лучше согласуется с экспериментальными данными, чем леннард-джонсовская изотерма, хотя это различие не является существенным.
Таким образом, термодинамическая теория возмущений и модель парных межмолекулярных взаимодействий вполне адекватно объясняют происхождение одного из экспоненциальных членов в выражении (11), отвечающего короткодействующим структурным силам. Вместе с тем, хорошее согласие с экспериментом свидетельствует о том, что вклад дальнодействующей компоненты структурных сил, обусловленный ориентационными эффектами, является для исследуемой системы пренебрежимо малым. Таким образом, по крайней мере для смачивающих слоев неполярных жидкостей типа декана мнение о заметной роли ориен-тационных эффектов в устойчивости смачивающих слоев [11,16] не подтверждается.
ЛИТЕРАТУРА
1. Дерягин Б.В., Чураев Н.В., Муллер В.М. Поверхностные силы. М.: Наука. 1985.
2. Мартынов Г.А. // Коллоид.журн. 2000. Т.62. №3. С.154.
3. Samsonov V.M., Rumyantsev A.A.//XII International Conference "Surface Forces", June 29-Jule 5.2002. Zvenigorod. 2002. P.80-82.
4. Щербаков Л.М.//Исследование в области поверхностных сил. М.:Наука.1964 C.17.
5. Samsonov V.M., Shcherbakov L.M., Novoselov A.R., Lebedev A.V. //Colloids and Surfaces. 1999. V.160. Issue 2.P.117-121.
6. СамсоновВ.М., Муравьев С.Д., БазулевА.Н. // Журн. физ. хим. 2000. Т.74. №11. С.1971-1975.
7. Базулев А.Н., Самсонов В.М., Сдобняков Н.Ю. //ЖФХ. 2002. Т. 76. №11. С. 2073-2077.
8. Ruckenstein.E. // J.Colloid Interface Sci. 1996. V.179. P.136-142.
9. Blake T.D., Cayias J.L., Wade W.H., Zerdecki J.A.
// J.Colloid Interface Sci. 1971. V.37. №4. P.678.
10. Абрамзон А.А. Поверхностно-активные вещества. Л.: Химия. 1981.
11. Семашко О.В., Усьяров О.Г. //Коллоид.журн. 2000. Т.62. №2. С.232.
12. Китайгородский А.Н. Органические кристаллы. М.: Химия. 1955.
13. Гордон А., Форд Р. Спутник химика М: Мир. 1976.
14. Бредшнайдер С. Свойства газов и жидкостей. М.: Химия. 1966.
15. Schiff D. // Phys. Rev.B. 1960. V.186 N.1. P.151.
16. Смирнова Н.А. Методы статистической термодинамики в физической химии. М.: Высшая школа. 1982.
17. Алтоиз Б.А., Поповский Ю.М. Физика поверхностных слоев жидкостей. Одесса: Изд-во ОГУ. 1996.
6
O. VOGT, J. RAKOCZY, J. OGONOWSKI, M. MIZDRA, M. BISOK, D. NOWAK
UTILIZATION OF THE WASTE FRACTION OF MONOHYDRIC ALCOHOLS FOR SYNTHESIS
OF A PVC PLASTICIZER
(Institute of Organic Chemistry and Technology, Cracow University of Technology, Krakow, Poland)
The possibility of application of the alcoholic waste fraction obtainedfrom Cyclopol process as a raw material for synthesis of PVC plasticizers was investigated. First, the methodology for esterification of the fraction was developed. The „simplex" method was applied for optimisation of the process parameters. PVC paste containing the synthesized plasticizer was prepared. Next, rheological tests of the PVC paste were performed and strength of the PVC foils obtained from the paste after gelation were studied. The PVC foils obtained showed good and useful properties. On the basis of these results it is concluded that the esters obtained can be industrially applied as non-expensive plasticizers for PVC.
INTRODUCTION waste compounds are produced. Usually, they are util-
The production of cyclohexanone by oxidation ized by combustion. Mixture of monohydric alcohols is
of cyclohexane is one of the specialities of Polish fun- an example of such undesirable products. In view of eco-
damental chemical industry. During this process many logical aspects, other methods of the alcohols utilization
are developed. Analysis of the composition of the waste alcoholic fraction let us suppose that it can be used as the raw material for production of a PVC plasticizer.
PVC is often used as thermoplastic polymer like polyethylene and polystyrene. Without additives such as plasticizers, stabilizers, fillers, pigments and many others, PVC products are hard, fragile and opaque. Plasticizers are the most important PVC additives. About 70 % of plasticizers in use are esters of phthalic acid, so esters comprise the most important class of plasticizers [1,2].
Phthalic anhydride and alcohols obtained from oxo process (1-butanol, isobutanol, 1-octanol, isooctanol, mixtures of C9 and C10 alcohols), from Ziegler's method in Alfol process (non branching alcohols) as well as alcohols C7 - C15 coming from alpha-olefines are used for the esters synthesis [3, 4].
The organic phase of the waste - fraction obtained from Cyclopol process includes mainly mono-hydric alcohols (Table 1).
Table 1.
Composition of the organic phase of the waste fraction obtained from Cyclopol process.
Component [wt%] Component [wt%]
alkanes C5 - C7 0,70 1-propanol 1,10
alkenes C6 0,08 1-butanol 11,00
dienes C6 0,02 1-pentanol 58,40
benzene 0,02 cyclopentanol 8,60
ketones C3 - C6 12,90 cyclohexanol 0,50
aldehydes C5 - C6 3,88 other 2,80
H2O content reach a maximum of 3 wt.%.
While taking into consideration the large importance of phthalates of aliphatic alcohols as PVC plasticizers we made an attempt to synthesize the plas-ticizer by esterification of the waste alcoholic fraction with phthalic anhydride.
RESULTS AND DISCUSSION THE PLASTICIZER SYNTHESIS
In the first part of our investigations we developed the methodology for esterification of the waste alcoholic fraction. We checked the possibility of carrying out this process both without a catalyst and in the presence of such catalysts as: HCl, H2SO4 and amorphous aluminosilicate. These investigations have shown that only sulphuric acid gives satisfactory results.
The highest conversion was obtained when we used the stoichiometric excess of the waste fraction and removed the water produced. The «simplex method» was applied for optimisation of the process parameters (Fig. 1). Two parameters of the experiment: the esterification time and the amount of the alcoholic fraction were taken as the variables, while the
amounts of phthalic anhydride and the catalyst were kept constant. The esterification was carried out at the temperature 408 - 413 K. To remove the volatile components, atmospherical distillation was applied. The plasticizer was purified by vacuum distillation. The fraction boiling in temperature range 330 K and 500 K was collected. The plasticizer obtained was a clear slightly yellow liquid with a characteristic smell.
240 -
.2 220 -
200
£ 180 -
160 -
140
experiment number 1
(164.5) (206.1) (65.6)
(10.1)
yield of the plasticiser [g]
'—I—'
1—1—I—1—I—1—I—1—I—1—I—1—I—1—I
0
1
8
2 3 4 5 6 process time [h]
Figure 1. Estimation of optimal parameters of the esterification by the "simplex method".
We conclude that the optimisation method used is the simple way to determine the process parameters, which give the maximum yield of the plasti-cizer. The product mixture obtained in the experiment corresponding to the maximal yield of plasticizer contained: water (9.3 wt %), light components (15.2 wt %), vacuum distillation products boiling up to 330 K (4.4 wt %), plasticizer fraction (65.6 wt %) and the residue (4.7 wt %). There was 0.8 wt % of unaccounted losses that comprised the losses of volatile components during the distillation and the residues remaining on glassware walls after distillation.
ESTIMATION OF PLASTICIZER QUALITY.
Using the fraction containing mixture of phthalates we prepared the PVC paste. Next, rheological tests [5] of the paste were performed. The rheological analyses were repeated for the same samples after different storage times (Fig. 2). On the basis of the results obtained stability of the pastes was determined. The stability parameter is very important for storage of such materials. For comparison, PVC pastes containing n-butyl and n-octyl phthalates as plasticizer were prepared. In all cases the weight ratio of PVC to the corresponding plasticizer was 1: 1.25.
The results obtained indicate that the PVC paste with n-octyl phthalate has the best stability. However, the properties of the paste containing the prepared plasticizer are similar to those of the paste, containing n-butyl phthalate (Fig.2).
XHMH3 H XHMHHECKAS TEXHOœrHfl 2003 TOM 46 Btm. 5
101
Table 2.
The tensile strength of PVC foils (average values from several measurements).
sample thickness [mm] sample width [mm] sample Cross section [mm2] F max [N] max stress [N/mm2] max elongation [mm] relative elongation [%]
The foils containing n-octyl phthalate as a plasticizer
3.50 10.00 35.00 46.37 1.32 51.14 102.3
The foils containing the prepared plasticizer
3.50 10.00 35.00 68.29 1.95 97.96 195.90
2500
2250 -
2000
rtn 1750 cs
[L1500 -■&1250 -
CO
° 1000 CO
> 750 -500 250 0
150 200 250
time [h]
Figure 2. The viscosity of the PVC pastes containing different plasticizers versus the storage time.
On the basis of the results obtained we conclude that the prepared plasticizer from the waste alcohol fraction from the Cyclopol process can be applied industrially where n-butyl phthalate has been applied.
Next tensile strength of plasticized PVC foils was studied. The foils were prepared by gelation of the pastes. Their tensile strength was measured with ZWICK 1445. The following measurement parameters were applied: initial power = 0.2 N, testing speed = 100 mm/min, length of the samples L0 = 50 mm.
The results obtained are shown in Table 2 and Fig. 3.
80 -,
Z 60 u.
S 50 -
0
t! 40 -g
ni
1 30 -Й 20 -
10 0
with n-octyl phthalate
125
50 75
elongation AL [mm]
Figure 3. Stretching characteristics of the PVC foils.
The results obtained indicate that the PVC foil containing the synthesized plasticizer show higher tensile strength than the strength of the foil plasticized with n-octyl phthalate (Table 2 and Figure 3). Young modulus of the PVC foil plasticized with n-octyl
phthalate is slightly higher than that of the foil plasticized with the prepared plasticizer as indicated by the slopes of the stretching characteristics (Figure 3). However, the latter foil endures higher stress and proceeds to higher elongation before it breaks.
These data confirm that the phthalic esters obtained on the basis of the waste alcoholic fraction from Cyclopol process are good candidates for synthesis of non-expensive plasticizers for PVC. These new plasticizers can supplement or replace n-butyl phthalate and n-octyl phthalates in industrial applications.
CONCLUSIONS
1. The waste fraction obtained during the production of cyclohexanone from cyclohexane can be used to manufacture a PVC plasticizer.
2. From among the catalysts studied sulphuric acid is the most effective catalyst for the esterification of phthalic acid with the waste fraction.
3. The plasticizer obtained was a clear slightly yellowish liquid with characteristic smell. This property limits its practical application to coloured products.
4. PVC paste containing n-octyl phthalate plasticizer shows the best stability during storage from among the pastes studied. However, the prepared plas-ticizer forms PVC pastes of comparable stability to that of the paste based on n-butyl phthalate.
5. The foil obtained by gelation of the PVC paste containing the synthesized plasticizer shows higher mechanical strength than the foils obtained by gelation of the PVC / n-octyl phthalate paste.
LITERATURE
1. Oblój-Muzaj M., Swierz-Motysia B., Szablowska B.
Polichlorek winylu, WNT, Warszawa 1997, s.65.
2. WHO report Environmental Health Criteria: Diethyl-hexyl phtalate., Genewa, 1992.
3. Maciaszek St. „Plastyfikatory tworzyw sztucznych. Cz^sc I", Chemik 1980, 7-8, s. 224 - 227.
4. Maciaszek St. „Plastyfikatory tworzyw sztucznych. Cz^sc II", Chemik 1980, 10, s. 303 - 309.
5. PN-EN 535:1993 (ISO 2431 edition 1984 modified), "Paints and varnishes - Determination of flow time by use of flow cups".
