INTRODUCTION:

Pet used in various applications like food container, bottle, plastic fibers, toys, wrapping materials, films and resins. Poly ethylene terephetalat is one of the highly requested plastic in the world. Poly ethylene terephetalat (PET) is thermoplastic polyester. PET has a good electrical insulating properties, Low water absorption, high hardness and strength .Plastics used highly in daily life, because plastic are flexible and cheap and have a many application. Despite all of the plastic benefits they remain in the environment. Plastic waste can be seen everywhere because plastic not biodegradable and remain in the environment for many years. Because of slow degradation of plastic materials they caused a problem in landfills and also make problem in collection of solid waste. There are ways for solve the plastic waste problem like source reduction and recycling.

Recycled plastic has a low performance because their properties reduce during recycling process. Recycling is a best way for reduce the amount of solid waste. Before recycling process PET should be separated from other waste.

PET recycling has a two form: Mechanical and chemical process. Mechanical process is most common way of PET recycling. In this method bottles and other PET base material must be washed and grinded. The resulting flaks blend with virgin PET in various percent according to future applications.

Most industries consider recycle PET as a good row material due to its chemical properties, good thermal resistance.PET Molecular weight reduced because moisture absorption, biological contamination, oxidation, thermal degradation and high temperature. During recycling process, chemical and mechanical degradation occurred¹. Degradation of PET waste has an impact on mechanical properties of recycled PET². Chemical resistance and melt viscosity recycled of PET are less than virgin PET. Factors that could decrease physical, mechanical, chemical and rheological properties of recycled PET also causing brittleness of this recycled polymer. This factor also leading to loss of melting elasticity behavior of recycled PET.

Polycarbonate is a thermoplastic polymer has a many applications³. Polycarbonate is though and transparent. Polycarbonate has a good thermal resistance and impact resistance.

Polymer alloying is suitable technique for production and development of new materials. In this method two or more polymer combined together and alloy have excellent properties more than primal polymer. This method not expensive and will give a result in short time. The blending of two or more polymer is a way for improve application of primary polymers.

In this article recycled PET blended with polycarbonate to improve mechanical properties of blend. .recycled PET prepared from used bottle.

EXPERIMENTAL:

Material: Waste Poly ethylene terephetalat obtained from used bottle and washed to remove pollutant. Recycled PET was grind to prepare flakes. Flakes washed again. Polycarbonate obtained from BASF Company. Ethylene Acrylate Terpolymer used as a compatibilizer obtained from Dupont Company.

Method: Materials dried in oven for 16 hours at 110 °C. Alloy prepared in twin-screw extruder with 150 rpm at 260 ° C.

The tensile properties were measured by instron 6025 testing machines. Morphological observation was done by Oxford Instruments INKA Penta FET×3 scanning electron microscope at voltage 20 KV. Samples fractured in liquid nitrogen, then sputter coated with gold 18 carat.

RESULT AND DISCUSSION:

Recycled PET was alloyed with various amount of polycarbonate. Table 1 gives the amount of polycarbonate and recycled PET.

Table 1 amount of polycarbonate (PC) and recycled pet (R-PET) alloy

Alloy	R-PET	PC
R-PET/PC	100	0
R-PET/PC	80	20
R-PET/PC	60	40
R-PET/PC	50	50

Table 2. mechanical properties of recycled PET/Polycarbonate alloy

Alloy	Elasticity modulus (GPa)	Tensile strength (MPa)	Elongation at break (%)
Recycled PET( R-PET)	29/1	52	598
R-PET/PC (80/20)	55/1	55	560
R-PET/PC (70/30)	65/1	57	288
R-PET/PC (60/50)	80/1	59	165
R-PET/PC (50/50)	98/1	61	100
Polycarbonate(PC)	22/2	72	91

Polycarbonate and recycled PET have different polar characters are compatible with each other. During the melt alloying sterification reaction take place. Sterification reaction between Polycarbonate and recycled PET cause enhance in recycled PET properties. With increasing the amount of polycarbonate properties such Transparency, impact resistance and tensile strength improved.

Mechanical properties of recycled PET/Polycarbonate alloys were shown in table 2. With increase the amounts of polycarbonate elasticity modulus increase significantly. Recycled PET has a lower tensile strength in comparison with Polycarbonate; Polycarbonate has a two phenyl aromatic cycle in this chain that cause a higher tensile strength than recycled PET. Polycarbonate improves the tensile strength of recycled PET/Polycarbonate alloys. The maximal elasticity modulus and tensile strength belong to R-PET/PC (50/50) blend. Elongation of break decreased with increasing polycarbonate. This can be explained the polycarbonate is though materials so has a low elongation at break.

PET properties decreased after recycling process, so usage of polycarbonate could be a good solution for that problem. So for enhance the tensile strength, Toughness in low temperature and high thermal stability.

(a)

(b)

(c)

(d)

Fig 3. Scanning electron micrograph (SEM) of recycled PET/Polycarbonate with different amount, (a) R-PET/PC (80/20), (b) R-PET/PC (70/30), (c) R-PET/PC (60/50), (d) R-PET/PC (50/50).

Fig 3 shows the scanning electron micrograph (SEM) of recycled PET/Polycarbonate alloys. SEM shows that blend morphologically are homogenous. There are few large particles in the matrix. Large particle can be seen in the sample with higher percent of PC. Internal interaction between two particles in the blend is intensive. With decreasing radius of the particle, adhesion between the surface increases. Hence, distribution of polycarbonate particle in PET matrix improved. Recycled PET and polycarbonate has a close crystallization temperature. Because of compatibility between Recycled PET and polycarbonate didn’t use any compatibilizer. If compatibilizer used the dispersed phase particle size will be smaller. With decrease particle radius the adhesion between the surfaces of two martial increases. Distribution of polycarbonate particle in the main phase of PET improved.

CONCLUSION:

PET has a various application but it’s not degradable in environment. Recycling is the best way for reduce PET solid waste. During recycling process some of the mechanical and thermal properties of recycled PET decreased. Alloying Recycled PET and polycarbonate improved the properties that decreased during recycling process.

ACKNOWLEDGEMENT:

This research supported by the research fund of Damavand Branch, Islamic Azad University, Iran.

REFERENCES;

1. Fraı¨sse F. Verney V. Commereuc S. and Obadal M. Recycling of poly(ethylene terephthalate)/polycarbonate blends. Polymer Degradation and Stability. 90 :2005: 250-255.

2. Fechine G.J.M. Souto-Maior R.M. and Rabello M.S. Structural changes during photodegradation of poly(ethylene terephthalate). Journal of Materials Science. 37(23): 2002: 4979-4984.

3. Liao ZL. and Chang FC. Rubber-Toughened polymer blends of polycarbonate (PC) and poly (ethylene terephthalate (PET). Journal of Polymer Research. 1(2): 1994: 197-203.

Received on 13.07.2011 Modified on 14.08.2011

Asian J. Research Chem. 4(10): Oct., 2011; Page 1539-1541