Study on In-situ Compatibilized Polyvinyl Chloride/Polystyrene Blends Catalyzed by Anhydrous Aluminum Chloride. Hong-mei NIU and Kan-she LI

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1 2017 2nd International Conference on dvanced Materials Science and Environment Engineering (MSEE 2017) ISN: Study on In-situ Compatibilized Polyvinyl Chloride/Polystyrene lends Catalyzed by nhydrous luminum Chloride Hong-mei NIU and Kan-she LI College of Chemistry & Chemical Engineering, Xi an University of Science & Technology, Xi an; , China Keywords: Polyvinyl chloride, Polystyrene (PS), Friedel-crafts alkylation reaction, In-situ compatibilization, nhydrous aluminum chloride. bstract. In order to improve the compatibility of the blend, the in-situ compatibilization of polyvinyl chloride and polystyrene blends (PVC/PS) were prepared successfully in the presence of anhydrous aluminum chloride. The structure of PVC/PS blends was characterized by FTIR. The peaks of 1943 cm -1 and 838 cm -1 in FTIR spectrum revealed that the substitution for para-position of benzene was realized. The properties of PVC/PS blends were characterized by SEM, DSC, and tests of mechanical properties. The results show that adding appropriate amount of PS, anhydrous alluminium chloride and styrene, the interface adhesion of PVC/PS blends increased. The tensile strength increased from MPa to MPa, the notched impact strength of PVC/PS blends reached 5.3 kj /m 2, compared with 3.9 kj /m 2 of PVC, increased by 35.9%. The glass-transition temperature of PVC/PS blends is 89 between 83 of PVC and 106 of PS. The optimum adding amount of PS, anhydrous aluminum chloride and styrene is 6%, 0.6% and 9%, respectively. Introduction It is well known that the direct blending of two or more thermoplastic polymers in appreciable proportions can cause phase segregate, low interfacial adhesion and poor mechanical properties. The compatibilization technique can reduce the interfacial tension and increase the phase adhesion to obtain a stable morphology. Usually by adding the third component as the compatibilizer, to reduce the interfacial tension of the two-phase interface, increase the contact area of the two phases, and enhance the adhesion between the two phases to promote the two-phase compatibility. ut it is difficult to find suitable compatibilizers, as well as the synthesis method of compatibilizers is difficult. However reactive compatibilization technology has proved to be the best ones, which is the compatibilizer, usually a copolymer, is generated in situ by a reaction between the homopolymers [1]. PVC and PS as two general plastics have a wide range of applications. PVC resin is high strength, low cost, but the thermal stability of PVC is not good, requiring processing at a lower temperature, so the higher melt viscosity makes it difficult to produce hard PVC products. lending with PS can reduce the melt viscosity of PVC. However, the compatibility of PVC and PS is undesirable because of their large differences in solubility parameter values (δ), PVC is 20.13, PS is Lewis acid catalysts were widely used in the chemical industry as the classic catalysts for Friedel-Crafts acylation and alkylation reactions. They can also be used in polymerization and isomerization reactions of hydrocarbons due to outstanding catalytic activity [2]. lcl3 as a catalyst, PVC and PS occurred as follows chemical reaction, shown in Figure 1, the HCl is absorbed by the stabilizer. In this paper, anhydrous lcl3 was used as a catalyst, reactive blending and in situ compatibilization techniques were used to obtain a comprehensive mechanical property of PVC / PS alloy material [3-4]. lcl 3 CH 2 CH CH 2 CH + CH 2 CH + HCl Cl CH 2 CH Cl Figure 1. Grafting reaction principle of PVC and PS. 57

2 Experimental Details Materials Commercial PVC SG-5 was purchased from Xi'an chemical plant (China). Commercial PS GPPS-500 was purchased from China National Petroleum Corporation Dushanzi Petrochemical Company (China). nhydrous aluminum trichloride (lcl3), from Sinopharm Group Chemical Reagent Co., Ltd. (China). Preparation of lend Materials certain amount of PVC, anhydrous lcl3, and calcium and zinc composite stabilizer was added to the disc-type force chemical reactor, grinding 20 times, adding PS, and then grinding 5 times. The mixture was placed in an oven at 85 C and dried for 30 min; kneading in the XK-1 open mixing machine, 140 ~ 150, the blend was placed on a QL-25D/Q flat vulcanizer to be hot-pressed to obtain a PVC/PS test piece. Structure and Performance Characterization Respectively, the PVC/PS blends () and the simple mixture of PVC and PS () 5 grams each, was dissolved in 20 ml of tetrahydrofuran, to obtain a paste liquid, Kr smear and dried at 80 C for 30 min, tested on a Spectrum-GX infrared spectrometer (Perkin Elmer). The tensile test was performed using a dog-bone bar sample on an Instron mechanical tester at room temperature, with a cross-head speed of 20 mm/min (G/T ). The notched impact strength was measured (G/T ) on an XJ-40 impact tester. The PVC / PS blends samples immersed in liquid nitrogen for 20 min and then brittle, the morphology was observed on a Quanta 200 field emission scanning electron microscope (FEI). Respectively, PVC, PS and the PVC / PS blends, were scanned at a DSC 200 differential scanning calorimeter (Netzsch, Germany), 40 C ~ 250 C, heated at a rate of 5 K / min. Results and Discussion Structural Characterization Figure 2 shows the infrared spectra of PVC / PS blends () and PVC and PS simple mixtures () (PS mass fraction is 6%). It can be seen from Figure 2 that 1943 cm -1 and 838 cm -1 new peaks appear in the PVC / PS blends (), which are characteristic absorption peaks of the benzene ring-substituted in the para-position, it confirms that Friedel-Crafts grafting has occurred between PVC and PS. Due to the low PS content, the amount of "chlorinated hydrocarbons" is much larger than the amount of benzene ring, so that part of the substitution reaction occurs in the ortho-position of benzene ring, so the peaks position slightly redshift. Transmittance (T%) PVC-g-PS mixrure of PVC and PS Wavenumbers (cm -1 ) Figure 2. IR spectra of PVC / PS blend () and mixture of PVC and PS () with a mass fraction of 6%. Figure 3 shows the DSC curves for PVC, PS and the PVC / PS blends with PS mass fraction of 6%. It can be seen from Figure 3 that the Tg of the PVC is 83 C and the Tg of the PS is 106 C, while the PVC / PS blend has only one Tg of 89 C and is between the two. In general, when the compatibility 58

3 is good between the two components, the system tends to form homogeneous system; the blend has only one Tg and is between the Tg of the homopolymer of the component. In Figure 4, the curve is the tensile strength of the PVC / PS blend varies with the PS mass fraction when the lcl3 content is 1.0%. Curve shows the relationship between the tensile strength of the PVC / PS blend and the PS mass fraction without lcl3. It can be seen from Figure 4 that the tensile strength of PVC / PS blends decreases rapidly with the increase of PS content from MPa to MPa when lcl3 is absent. The curve shows that the tensile strength of PVC / PS increases first and then decreases with the increase of PS content when lcl3 is added. The possible reason is that with the increase of PS content, more compatibility agent, graft copolymer, is produced to increase the compatibility of PVC / PS. Finally, with the increase of PS, excessive PS additions make system compatibility worse, which leads to the decrease of mechanical properties of PVC / PS exo C PVC PVC-g-PS C PS DSC (mw/mg) o C 89 o C 106 o C Temperature ( o C) Figure 3. DSC curves of PVC (), PVC /PS blends () and PS (C). Tensile Strength (MPa) with lcl 3 without lcl Content of PS (wt%) Figure 4. Effect of PS content on tensile strength of the blends. In Figure 5, the curve is the change of the notched impact strength of the PVC / PS blends with the PS mass fraction without lcl3. Due to there is no compatibility between the two-phase interface, the interface adhesion is poor, with the increase in PS content, the brittleness of the PVC / PS blends increases and the notched impact strength decreases. Curve shows that the notched impact strength of PVC / PS blends is affected by the change of PS mass fraction when lcl3 content is 0.4%, with the increase of PS content, the notched impact strength of PVC / PS showed a decreasing trend, which decreased from 3.9 kj / m 2 of PVC to 2.7 kj / m 2 when the PS content was 10%. Compared with the curve, curve shows the downward trend of notched impact strength is obviously slow. It can be seen that the copolymer produced by the Friedel-crafts alkylation reaction increases the adhesion between the two phases to a certain degree. 59

4 with lcl 3 without lcl 3 Content of PS (w%) Figure 5. Effect of PS content on notched impact strength of the blends. In Figure 6, curve and curve show the influence of the tensile strength and the notched impact strength of PVC / PS blends on the amount of lcl3, respectively, and the PS mass fraction is 6%. It can be seen that the tensile strength of the blend is low when there is no lcl3, only MPa. With the increase of the amount of lcl3, the grafting rate increases and the tensile strength increases accordingly. When the mass fraction of lcl3 is 0.6%, the tensile strength of the PVC / PS blend reached a maximum of MPa. Curve shows that the notched impact strength also increases first and then decreases with the increase of lcl3 content and the higher value is obtained when the mass fraction of lcl3 is 0.4% ~ 0. 6%. 5 Tensile strength (MPa) Tensile strength Notched impact strength Content of lcl 3 (wt%) Figure 6. Effect of lcl3 content on mechanical properties of the blends. While the PS mass fraction is 6%, Figure 7 are some scanning electron micrographs of the cross section obtained in liquid nitrogen of the PVC / PS samples. Image can hardly see the phase interface between the dispersed phase PS and the matrix PVC, the two phases are evenly distributed, the phase interface is blurred; while the pits in image are the dispersed phases PS, PVC and PS show obvious two-phase structure, in which PS is distributed irregularly in the matrix material PVC, and the distribution is uneven and the particle size is obviously different. Further study, image C and Image D reflect the same rule. with lcl () without lcl () with lcl (C) Figure 7. SEM photographs of the blends of PVC / PS. without lcl (D) In the blending process, the smaller the PS particles in the dispersed phase, the larger the contact area of the matrix PVC, which results in a greater amount of carbon positive ions, and the larger carbon cation concentration makes the PVC more easily reactive with the PS, compatibility improved. Figure 8 shows the relationship between the grinding times and the tensile strength and notched

5 impact strength of PVC / PS blends. It can be seen that with the increase of the grinding times, the tensile strength increases first and then becomes constant. The reason may be that the grinding times increases to a certain value, the reaction tend to be balanced. When the grinding times is less than 15 times, the notched impact strength of the blends is almost unrelated to the grinding times, when the grinding times is greater than 15, the notched impact strength of the blend increases with the grinding times; when the number of grinding times is more than 25, the particles of PS are no longer significantly reduced, and the notched impact strength is no longer improve. Tensile strength (MPa) Notched impact strength Tensile strength Times of grinding Figure 8. The influence of grinding times on mechanical properties of the blends of PVC /PS. Further, we added a certain proportion of styrene monomer (St) to the mixture, the results shown in Figure 9. Figure 9 shows the relationship between the mass fraction of St and the mechanical properties of the blend. It can be seen that the tensile strength and the notched impact strength show a tendency to increase first and then decrease with the increase of the amount of St, and the tensile strength reaches Mpa when the mass of St is 6%, and the notched impact strength reaches the maximum value is 5.3kJ / m 2 when the St mass fraction is 9%. The reason is that a small amount of St polymerization to produce low molecular weight PS, in the presence of lcl3. t the same time, the oligomer PS is grafted on PVC, and the graft copolymer acts as a compatibilizer, further reducing the tension of the two-phase interface; when the St monomer content exceeds a certain value, the excess St reduces the force between the PVC molecules, played a role in the plasticizer. Tensile strength (MPa) Tensile strength Notched impact strength Content of St (%) Figure 9. The influence of St content on mechanical properties of the blends of PVC /PS. Conclusions With anhydrous lcl3 as a catalyst, in situ produce grafted polymers by Friedel-crafts alkylation reaction of PVC and PS, the comprehensive mechanical properties of the alloy was obtained. When the PS mass fraction is 6%, the amount of anhydrous lcl3 is 0.6%, the tensile strength of PVC / PS is increased to MPa, which is 14% higher than that of pure PVC, under the same conditions, the notched impact strength of the PVC / PS blend material is 3.8 kj / m 2, slightly lower than the 3.9 kj / m 2 of pure PVC. y adding St, grinding the raw materia by disc-type force chemical reactor, can effectively improve the notched impact strength, the optimum conditions were as follows: the mass fraction of St was 9% and the grinding times were 25 times, under this condition, the tensile strength increased from MPa to MPa, and increased by 23.7%; the notched impact strength was 5.3 kj / m 2, which was 35.9% higher than that of PVC at 3.9 kj / m 2. 61

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