Utilisation of Photo Activators to Produce of Low Density Polyethylene Based Photodegradable Composite Materials

Abstract

Polymeric materials are branch of our daily life and have found in a wide variety ofapplications. Synthetic polymers now constitute one of the most successful and useful classesof materials and possess a broad range of useful physical properties. Today, there is anincreasing concern about the protection of our ecological systems. Most of today’s syntheticpolymers are produced from petrochemicals and are not degradable. Many polymers do notreadily decompose due to some natural factors like high temperatures or sunlight. In someways, this non degradation is a positive aspect of some polymers since it permits to designdurable and long lasting polymer items but it provides negative effect when polymers use forshort term applications like packaging. They create significant problems by piling up inlandfills. About twenty five percent of all domestic waste products in landfill sites arecomposed of various polymer packaging items. There is a world-wide research effort todevelop phodegradable polymers as a waste management option for polymers in theenvironment. Photodegradable polymers are especially designed in order to control theirdegradability when exposed to sunlight in the environment. The failure of photodegradablepolymer depends on indiscretions in the polymers. These abnormities cause polymers togradually degrade when exposed to ultraviolet (UV) light, normally sunlight. Inphotodegradable polymers, the speed of degradation is increased by adding photo - activators.The objective of this research is to produce photodegradable Low Density Polyethylene(LDPE) based composite materials with the help of photo - activators. ZnO was used as aphoto - activator in this research.

ZnO is a material which is of great interest for a variety of applications due to its uniqueproperties and the availability of a variety of growth methods resulting in a number ofdifferent morphologies and a wide range of material properties. ZnO (p-type) of band – gap3.24 eV with 0 -150 μm particles were used to produce composite in this research.Laboratory scale blender was used to mix the LDPE and ZnO particles by varying 1 wt% to 5wt% of ZnO. Mixing parameters were temperature 1500C, speed of the rotor 60 rpm and10minutes mixing time. Mixtures were prepared without significant phase separation. LDPE -ZnO based composite samples were prepared by using hydraulic press. Ultraviolet exposuretest, water absorption test and tensile test were performed to evaluate the degree of photodegradability.Additionally, colour changes also observed during the ultraviolet exposure test.ZnO containing samples showed the reduction of tensile properties and higher waterabsorption properties during the ultraviolet exposure testing period. Pure LDPE did not showthe significant tensile strength varialtion during the testings. Significant colour changes alsoobserved in ZnO containing samples with compared to pure LDPE during the testing time.According to these experimental results developed LDPE - ZnObased photodegradablecomposite materials can be used as an alternative material to the conventional polymerproducts to build a green environment.