Study of the effect of solid waste reinforcing on the thermal behavior of a nanocomposite

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Chraibi & al. / Mor. J. Chem. 2 N°5 (2014) 490-493 EDE4

490

Study of the effect of solid waste reinforcing on the thermal behavior of a nanocomposite

S. Chraibi â, M. Allouch â, F. Boukhlifi ^b, M. Alami â

a. Equip Materials, Metal and Engineering industry of the Processes, ENSAM, Meknes, Morocco b. Materials and Applied Catalysis, FSM, Meknes, Morocco

*Corresponding author. E-mail : [email protected]

Received 13 sept 2014, Revised 01 oct 2014, Accepted 24 Oct 2014.

Abstract

In our work, we are interested in polystyrene nanocomposites prepared by in situ polymerization by adding as reinforcement particles from solid waste. It has been shown that due to their small size, nanoparticles can be incorporated easily into the matrix and can provide very substantial improvements to mechanical, thermal and electrical properties of the nanocomposite. In this sense, we conducted our study on nanocomposites based on polystyrene (PS) as a reinforcement with CaCO₃ particles from solid waste at different load percentages, typically between 1 and 10% by weight. First morphological and structural analysis was performed using the scanning electron microscope (SEM) and the Fourier transform infrared spectroscopy (FTIR). After the in-situ synthesis by polymerization of these nanocomposites were studied new thermal degradation of the material based on the thermal aging by UV light and sunlight. To characterize the effect of this damage we used micrographs by optical microscope and a scanning calorimetry.

1. Introduction

The use of fillers has been a common practice in the plastics industry to improve the mechanical and thermal properties of the thermoplastic, such as heat distortion temperature, the melting or softening point, thermal stability, hardness the strength, stiffness and mold shrinkage. The effects of load on the properties of the composite are strongly dependent of the shape, particle size, aggregate size, surface characteristics and the degree of dispersion. In this sense some work on nanocomposites based on polystyrene as CdS / polystyrene [1, 2, 3], nanocomposite CdTe / polystyrene [4] and nanocomposites ZnSe / Polystyrene and ZnO / Polystyrene [5] showed an impressive improvement impact with the addition of rigid particles. The increasing use of composite materials creates management problems resulting waste. We then turned more and more towards the implementation of degradable products either by using degradable polymers treated either by incorporating loads in degradable composite materials. The major problem caused by the production of such composite materials is the poor quality of adhesion between the charge and the matrix, often resulting in a reduction of their use properties compared to the matrix alone. Other work products however incorporate natural origins, [6] a-clay nanocomposite polystyrene (PS) prepared by bulk polymerization using an organically modified montmorillonite (MMT). It has been shown that the stability of PS was significantly increased in the presence of clay, the heat emission is half that of the virgin PS, it is

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491 deduced that the clay acts as a promoter by slowing the degradation providing a protective layer (barrier) of nanocomposite. An inorganic charge can profoundly change the characteristics of a polymer system. The properties of the particles themselves (size, shape and module) can have a significant impact. The particle can act as a nucleating agent for crystallization to reduce the crystallinity or introducing the kinetic barrier [7], [8]. The load introduction CaCO3 in polypropylene by melt blending in a mixer gives an optimal dispersion of CaCO₃ nanoparticles PP [9]. Curing of polypropylene with rigid particles leads to a system with a greater rigidity and a more impact resistant. A polypropylene composite -CaCO3 showed improved toughness and a high young's modulus [8].

2. Experimental studies

In order to disperse the nanoparticles in an organic environment, the main problem to be faced is the risk of poor dispersion of these nanoparticles in the matrix. Compared to conventional methods, the in situ polymerization of monomers in presence of nanoparticles allows better control of the homogeneity of nanocomposite and the degree of interaction between the matrix and the nanofiber. We performed the synthesis of styrene from polystyrene and benzoyl peroxide. The degree of polymerization varies considerably with the operating conditions (concentration, temperature, initiator ...) and the length of the macromolecules in the polymer is not constant on this we have ensured that the nanocomposites different percentages of reinforcement are derived of the same base polymer.

3 Results and Discussion

3.1. Analyses structural and morphological

Following preparation of the polystyrene only and polystyrene strengthened with different percentages were made their characterization by IR, as shown in figure 1. By examining the IR spectra of the figure, we see that the characteristic bands of polystyrene were not affected by the addition of CaCO₃ extracted from egg shells, except in limited areas. The insertion of the CaCO3 in the polystyrene was carried out without substantial interaction, which coincides with the bibliography. [10]

Figure1. Results of infrared polystyrene and polystyrene reinforced with different percentages of CaCO3.

4000 3500 3000 2500 2000 1500 1000 500 0

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300

% Transmittance

1/Cm

poly+10%

poly+5%

poly+1%

polystyrène

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492 Analysis of Figures 2 and 3 shows that the appearance of the polymer changed completely. The transparent appearance polystyrene disappeared after adding reinforcements.

According to SEM analysis, it was found that the distribution of the reinforcement in the polymer is not regular.

Figure 2. SEM image of 100 microns polystyrene without reinforcement

Figure 3. SEM image of polystyrene 500 microns with 10% CaCO3

To measure the thermal degradation we performed heat aging by increasing the temperature, we measured sample weight every 30 min to define the mass loss. We noticed based on visual examinations that it is change color and transparency of the new nanocomposite. There is also the presence of bubbles and cracks.

The effect of this degradation has been observed with the optical microscope, after only 4h of the beginning of the experiment, the significant changes observed in polystyrene without reinforcement and same fractures appeared on the surface (Figure 4). In contracst no change appears for samples of polystyrene with reinforcement [11].

Figure 4. Electron microscope image of polystyrene without reinforcement after thermal degradation

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4. Conclusion

PS nanocomposites with CaCO₃ nanoparticles were prepared at different weight percentages by the in situ polymerization. The high temperature behavior has significantly increased thanks to reinforcements. CaCO3

nanoparticles have a flame retardant effect of preventing immediate combustion nanocomposites.

The effect of UV-visible was significantly limited by reinforcements, we observed a total lack of response to UV compared to pure PS. The CaCO₃ particles as inorganic reinforcement have improved thermal properties of PS.

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