Study the Properties of Irradiated Packaging Material-A Short Review

Abstract

Plastics become the most favourite use among society due to its own characteristics in aspect of barrier properties and strength, we are able to get them anywhere, plus they are cheap, resistible with water and very flexible. Also these days people would mould the polymer into any kind of shape. Lots of efforts have been done to reduce the amount of plastics but not work really well, even with the 3R program, reduce, reuse and recycle. For that reason, bioplastics are born to educate people for having better choices in saving the earth. Carbohydrate-based polymers were most famous as the polymers came from starch, cellulose, lactic acid and lactide, polyhydroxyalkanoates and chitosan which were easier to obtain, especially polymers from starch as it was the cheapest among others. Ratio of amorphous and crystalline regions play huge role in bioplastic. Using only starch and water is not enough to compete with polyethylene (PE) or polypropylene (PP). Therefore, plasticizers need to add in to enhance water barrier and mechanical strength. Plasticizers such as glycerol, sorbitol, citric acid and even beeswax have been tested in several studies for reducing water permeability. However, water permeability for bioplastic is quite high due to presence of water itself as plasticizer makes some bioplastic easier to attract water molecule. Fortunately, adding with other plasticizer will affect relative humidity (RH) where water content of material will follow it. Other than that, content of moisture test can tell the level of hydrophilicity of a material. Meanwhile, in contact angle measurement, sessile droplet mostly used for examine wettability. Angle of 0 labelled as the most hydrophilic and 180  for super-hydrophobic. When it  comes  to industrial use, gamma radiation and electron beams are generally involved. The reason for gamma radiation is because gamma rays are extreme in penetration and Cobalt 60 mainly used and often for sterilization purpose. Abstraction, recombination, disproportionation and polymerization are effect due to exposure of ionizing radiation which lead to crosslinking or degradation of the chemical bonds of polymer. Reaction of irradiation towards oxygen reported that formation of free radicals can occur. By the presence of free radical, crosslinking of the polymer may occur due to the potential possessed by the attacked chain. Nevertheless, result would not be equal for all polymer as different presence of molecule might react differently. In the end, the effect towards polymer can be figured out with examine molecular weight.