Acylation Reaction of Polystyrene with Organic Anhydrides and Investigation of the Physico-Mechanical Properties

The acylation reaction of polystyrene with organic anhydrides, such as maleic and ace-tic anhydrides were investigated in the presence of cationic catalysis (AlCl 3, BF3•O(C2H5)2, FeCl 3, SnCl 4, TiCl4, ZnCl2), to synthesise some polyfunctional (carbonyl −, carboxyl −, keto−, olefinic) polystyrene. The incorporation of functional groups to polystyrene were caused an increase of adhesion capability, physico-mechanical properties, elasticity and photosensitivity polyfunctional product. Eurasian ChemTech Journal 2 (2000) 131-135  2000 al-Farabi Kazakh St.Nat. University *corresponding author. E-mail: refika@selcuk.edu.tr Introduction The synthesis of new polymeric materials having complex properties has recently be-come of great practical importance to polymer chemistry as wall as plastic technology. Generally, the synthesizing of new polymeric materials can be prepared by either the polymerization of their monomers or chemical modification of polymers appropriate with in polymer technology, the acylation reaction is very imported for producing new polymeric materials from polystyrene polyfunctional groups, in industry [1-6]. Today, polystyrene (PS), which is widely used in industrial applications as polyolefins and polyvinylchlorides, is also used for the production of plastic materials, which are used instead of metals in technology. The acylation reactions, in polymer chemistry, especially to producing of new polymeric materials from PS are very important. In our earlier work [7-11], the some polyfunctional polystyrenes which were prepared with different functional groups for such as epichlorohydrine, organic anhydrides and unsaturated hydrocarbons, in the presence of cationic catalysts. Therefore, the adhesion capability and currovun resistance of the obtained polyfunctional products were increased against various type materials, i.e. metals, glass or wood. In this study, the chemical modification of polystyrenes with maleic anhydride and acetic anhydride were performed in the presence of cationic catalysts. The prepared polyfunctional polystyrene have different functional groups such as ( −C=C−; −CO−CH3; −CO−CH=CH−COOH), that the physico-mechanical, thermal, adhesion properties of the polyfunctional polystyrenes were investigated on the nature and the quantity of binding functional groups to the aromatic ring. In this paper we will briefly summarize all the aspects of the acylation reactions of PS with organic anhydride, and will be covered in previous specialized reviews, allowing for a broad and general discussion on the subject. The chemical modification of PS in the presence of cationic catalysts will be dis-


Introduction
The synthesis of new polymeric materials having complex properties has recently be-come of great practical importance to polymer chemistry as wall as plastic technology. Generally, the synthesizing of new polymeric materials can be prepared by either the polymerization of their monomers or chemical modification of polymers appropriate with in polymer technology, the acylation reaction is very imported for producing new polymeric materials from polystyrene polyfunctional groups, in industry [1][2][3][4][5][6].
Today, polystyrene (PS), which is widely used in industrial applications as polyolefins and polyvinylchlorides, is also used for the production of plastic materials, which are used instead of metals in technology. The acylation reactions, in polymer chemistry, especially to producing of new polymeric materials from PS are very important.
In our earlier work [7][8][9][10][11], the some polyfunctional polystyrenes which were prepared with different functional groups for such as epichlorohydrine, organic anhydrides and unsaturated hydrocarbons, in the presence of cationic catalysts. Therefore, the adhesion capability and currovun resistance of the obtained polyfunctional products were increased against various type materials, i.e. metals, glass or wood.
In this study, the chemical modification of polystyrenes with maleic anhydride and acetic anhydride were performed in the presence of cationic catalysts.
The prepared polyfunctional polystyrene have different functional groups such as (−C=C−; −CO−CH 3 ; −CO−CH=CH−COOH), that the physico-mechanical, thermal, adhesion properties of the polyfunctional polystyrenes were investigated on the nature and the quantity of binding functional groups to the aromatic ring.
In this paper we will briefly summarize all the aspects of the acylation reactions of PS with organic anhydride, and will be covered in previous specialized reviews, allowing for a broad and general discussion on the subject. The chemical modification of PS in the presence of cationic catalysts will be discussed [3][4][5][6].
The Lewis acids catalysis as BF 3 •O(C 2 H 5 ) 2 , TiCl 4 , SnCl 4 , FeCl 3 , ZnCl 2 and AlCl 3 were commercial products and the all were distilled under nitrogen atmosphere, diluted with chloroform and sealed in glass ampoules.

Modification
In a 250 mL flask, 5,2 g (0,05 mol) PS and 40 mL of chloroform were mixed and stirred for one hour, then this solution 0.98 g (0.01 mol) of MA (corresponding to 20 mol% MA with respect PS) was added and 1,4 mL the catalysts [BF 3 •O(C 2 H 5 ) 2 ] was added dropwise at the same temperature and were stirred for 2 more h. Modified PS was precipitated by methanol from the reaction mixture, filtered and dried under vacuum at 40°C for 5 h. Conversion is found as 6,0 g (97,5 %). The characteristics of the synthesized polymers were as following: Tg (by DCS analysis) 145°C, [η] in toluene at 25°C 0,75 dL/g, acid number (AN) 136 mg KOH/g, thermostability (by TGA analysis) 350°C.

Measurements and Analyses
The IR spectra of polymer films were recorded by use of (Py-Unicam Sp-1025) spectrophotometer.
Photosensitivity of thin polymer coatings formed on glass surface were determined by change of their optical densities in UV-irradiation. The Osram-Ultra Vitalax E 27 moderate pressure UV lamp (300 W) served as a source of irradiation.

Thermal analysis
Thermogravimetry (TGA) and different; al thermal analysis (DTA) experiments were carried out by use of a Paulik-Erday derivatograph system. The thermal stability of modified PS has been arbitrarily defined by initial loss observed with increase in temperature at 10 °C/min heating rate on the air atmosphere.
Differential Scanning Calorimeter analysis were realized by use of a Dupont TA 2000 at an under of 10 °C/min heating rate nitrogen atmosphere.

Physico-mechanic analysis
The adhesion capability, relative extension and resistance to stretch were determined by RMI-250 apparatus. In this measurement, the sample was determined by stretching.
Resistance to stretch (σ): It can be calculated as following: where, P, the weight to which the sample is subjected, kgf; a, the width of sample, cm; and h, the thickness of sample, cm.
The relative extension (ε') (%): It can be calculated as using the equation: where, l 0 , the initial part of working sample, mm; and l, the breaking part of working sample, mm.

Adhesion capability (A):
The adhesion capability is calculated by the using following equation: where, A, adhesion (MPA); P, the force for stretch, kgf; and S, the exposed surface area sample, cm 2 .
S= a×b a, the width of signboard, cm; and b the exposed adhesion area, cm.
Resistance to stroke (α): It was determined by resistance to stroke using KM-15-1 apparatus. The resistance to stroke at the breaking time could be calculated (according to standard 120×15×10 mm) from the following equation: where, W, the work for breaking the sample, kgf/cm.

Brinell Hardness (H B ):
The hardness Brinell was determined by AS-101/KM-2 apparatus and was measured as (N/mm 2 ) according to standard.
Resistance to heat (T v ): It was determined by FWA model Vika apparatus. The heat rate was 50 °C/h.

Results and Discussion
In our earlier paper, the some physico-chemical properties of the acylated reaction of PS with maleic anhydride by using of Lewis acid catalysts were investigated in the presence of cationic catalysts [10,11].
The acylation reaction mechanism of the PS with MA in the presence of BF 3 •OEt 2 catalysts is as following:

Scheme 1
The mechanism of the acylation reaction of PS with acetic anhydride in the presence of Lewis catalysts can be considered as shown on Scheme 2.
The anchoring of the CH 3 -CO -group to the aromatic ring of PS was confirmed by spectral and chemical methods, for confirmation of the anchored CH 3 -CO -group to the CH 3 -CO -group was converted to the (CHCOH)−CH 3 group by hydrogenation reaction with LiAlH 4 .
When compared of the bonding groups to the aromatic ring of PS between MA and AA as a mol%, the higher bonding was obtained with MA and this is found to be mine then that of AA. These results were also confirmed by determination of the kinetic parameters between MA and AA, under the same reaction conditions, and the obtained kinetic parameters are given in Table 1. As shown in Table 1, if the initial rate (W 0 ) and rate constant (K) of the acylation reaction between MA and AA are compared, the MA is almost 10-14 times higher than AA in the presence of BF 3 .OEt 2 catalysts. This fact is due to the stretching structure of MA and the effect of the catalysts.
The physico-mechanical, thermal and adhesion properties of the synthesized polyfunctional PS's are dependent on the nature of functional (CH 3 CO−; −CO−CH=CH−COOH) groups in the aromatic ring.
The results of for physico-mechanic, thermal and adhesion capability properties of the synthesized polyfunctional PS's are given in Table 2.
When the quantity of -CO−CH 3 bonding group to PS was increased from 4.4 mol% to 9.8 mol%, the following changes were observed; the resistance to stretch was increased from 53.9 to 62.0 MPA and the adhesion capability was also increased from 0.5−2.4 MPA. As shown in Table 2, the adhesion capability was increased, on the contrary, and difference in the resistance to stretch for the carboxyl and acetyl groups was not observed. These observations demonstrate that the different functional (carboxyl−, keto, acetyl−) groups can be attached to the aromatic ring of PS with various chemical modification conditions, and it is possible to obtain different technical properties for polymer materials. Table 2 Physico-mechanic, Thermal and Adhesion Properties of Functional Polystyrenes