مقالات علمی

In this work, we studied the effect of polyethylene glycol (PEG) with two different molecular weights (400 g/mol and 2000 g/mol) on the mechanical properties of polylactic acid (PLA). Samples including 5%, 10% and 15% PEG were prepared in a twin screw extruder and then injection moulded. The results showed that the young modulus and tensile strength of PLA decreased and elongation at break and impact strength increased as the loading amount of PEG increased. The sample with 15% PEG with molecular weight of 400 g/mol had the optimum properties, so Nano-silver particles (AgNPs) with different amounts (0.5, 0.015 and 0.075 phr) were added to it in order to investigate its mechanical and antibacterial properties. The results revealed that with increasing the amount of AgNPs, the young modulus and tensile strength of PLA increased and elongation at break and impact strength decreased. According to the SEM images, AgNPs were distributed uniformly thorough the PLA matrix. In addition, AgNPs had a significant effect on destroying bacteria and improving antibacterial properties. The sample including 0.075 phr AgNPs had the best antibacterial properties. Due to the importance of antibacterial properties in food packaging industry, this nanocomposite can be used in packaging films in order to prevent the growth of microbes on the food surface, decreasing the dosage of preservatives and finally increasing the life time of the food material.

The main purpose of this article is to improve the thermal properties of polypropylene (PP) by means of cyclic copolymer (CC). PP/CC blends were produced by the melt blending process. The heat deflection temperature (HDT) of compounds was measured. Heat deflection temperature of PP/50%CC compound were improved effectively. Mechanical properties consisting of tensile strength, impact strength, and flexural modulus were performed. The mechanical properties of compounds increased by increasing CC proportion except impact strength resistance.

Breathable microporous films are permeable to water vapor while providing a barrier to water in liquid state. These films are used in health care products as well as food and packaging industry. One approach in producing breathable films is by adding mineral filler to the polymer and stretching the film after it is produced. Presence of interconnecting network of micro pores allows the transmission of water vapor through the film various factors such as filler concentration, particle size, stretching method and heat setting temperature affect the breathability of the films. In this study, microporous breathable films and factors affecting their properties are reviewed.

The main purpose of this article is to improve the mechanical and electroconductive properties of polyethylene by means of glass fiber and graphite. A compatiblizer (0.5, 1, 2 wt%) was used to improve the compatibility of the PE/glass fiber compound. Graphite (15,20,30,40 wt%) was mixed with polyethylene compound. Mechanical tests consist of tensile strength, impact strength, and flexural modulus were performed. The results of mechanical properties and electrical conductivity showed that the optimal amount of graphite was 20% by weight and also the amount of 20% graphite was suitable for electrical conductivity, for this reason, this compound can be used in industrial applications such as the automobile industry.

The main purpose of this article is to improve the thermal properties of polypropylene (PP) by means of cyclic copolymer (CC). PP/CC blends were produced by the melt blending process. The heat deflection temperature (HDT) of compounds was measured. Heat deflection temperature of PP/50%CC compound were improved effectively. Mechanical properties consisting of tensile strength, impact strength, and flexural modulus were performed. The mechanical properties of compounds increased by increasing CC proportion except impact strength resistance.

Investigation of biodegradation behavior of biopolymers direct material designer to select the best material for special application. Main purpose of this lecture is analysis of biodegradation behavior and mechanism of biopolymers including polycaprolactone, polylacticacid, chitosan, polyvinyl lcohol and cellulose. polyvinylalcohol has been degraded  completely,however; Ultimate biodegredation of PCL is only 5 percent. PCL degreded at 400 degree has the most thermal degredation temprature. Chitosan with thermal degredation of 298 degree has the lowest thermal resistance.Cellulose illustrate the best mechanical properties in comparison with other biopolymers.