Vehari : A permanent waste dumping ground near Quaid-i-Azam Road. - Dawn

Alternative to  Plastic Shopping Bags

Plastic packaging is extensively used in all sorts of food and drug packing and in many household applications. Conventional plastic shopping bags, made of polyethylene, do not degrade and have become a serious source of pollution. They frequently end up clogging drains and making the gutters overflow. In cities and towns the stagnant sewerage water leads to bacterial germinations, water borne diseases and the spread of mosquitoes while in the rural areas these bags also affect the agriculture and suffocate animals mistaking bags for food. Banning the production and sales of plastic bags is not the whole answer as it will not only affect businesses worth million of dollars and make thousands of persons redundant but also there are so many purposes for which the bags are ideally suitable.   

There is increasing activity by the Government to address the huge problems of litter and waste and a number of important proposals are currently being considered to tackle the dilemma. While plastic bags are a major contributor to these problems, the availability of photodegradable plastic bags in Pakistan now provides an opportunity to the legislators to encourage their use and thereby mitigate the adverse effects which have been traditionally associated with the non-degradable plastic bags.

Production of Photodegradable Plastic Bags  

New Emerging Technology Limited has developed the technology for the production of photodegradable plastic bags. The technology is primarily based on the addition of 1 % of Degradable Polymer Additive (DPA-47) in polyethylene resin during the manufacturing process. Similar processing conditions during the extrusion as regular polyethylene are used in the same way to produce finished goods. The technology can therefore be used by a wide range of existing manufacturers without major processing cost increases. The degradable plastic shopping bags perform like normal plastic bags. It is light weight. It is also strong and has same mechanical properties, good sealing, printing and barrier properties like the traditional bag.  

1. Outdoor Weathering Study

 The degradable plastic bags along with conventional bags were exposed to the outdoor environment of Islamabad , Lahore , Faisalabad , Multan , Karachi and Peshawar . No changes in the traditional polyethylene bags were visible whereas the degradable plastic shopping bags were physically broken down within two weeks of exposure and the degraded material was totally oxidized and disappeared after 90 – 100 days.  

2. Testing of Bags

The outdoor weathered bags were characterized by FTIR, GPC and uniaxial Tensile Test. Results are presented in figures 1 – 4. The build up of carbonyl group at 1715 cm^-1 indicate that chemical reaction is taking place in the degradable plastic bag (fig.1) which leads to break down of the main carbon – carbon bond in polyethylene bag thus reducing the molecular weight of the material (fig.2). Figures 3 and 4 show that not only the tensile strength has gone down but also the nature of the fracture has changed from ductile to brittle as is indicated by a major reduction in the elongation at break. It can be concluded from these results that ordinary shopping bags currently being used in the market have excellent resistance to the outdoor weather and indicate no sign of degradation while bags containing DPA-47 degrade and disintegrate extensively within 2 weeks on exposure to the outdoor environment .  

3. Food Safe Bags

Migration test to study the “food Safe Bags” were carried out by Rapra Technology Ltd of England . The results show that degradable bags meet European Union Specification (EC Directive 2002/72/EC and subsequent amendments) and are therefore certified safe for direct food contact.  

4. Environmental Safety

Tests were conducted by Ayub Agriculture Research Institute Faisalabad and National Agriculture Research Centre Islamabad by sowing wheat and potatoes crops in soil which has large quantity of degradable plastic remnants. No toxic or adverse effects on crop or soil have been reported.  

5. Shelf Life & Storage

Degradable Bags can be stored indoors for a long time without loss of properties unless exposed to direct sunlight continuously for Several days.      

6. Recycling

Recycling of photodegradable PE bag is possible before degradation of material takes place.  

7. Testing by Independent Organizations

Photodegradable plastic bags were extensively characterized by Pakistan Institute of Nuclear Science and Technology (Pakistan Atomic Energy Commission) Islamabad and Plastic Technology Centre Karachi. Oven ageing and accelerated weathering tests were also conducted. The results are presented in table 1 and figure 5 and indicate clearly that rapid reduction in elongation at break is primarily due to the UV radiation in the sunlight.  

8. Cost

This technology is highly cost effective and is considerably less expensive as compared to other technology available in the market. There is approximately 5 % increase per kg in the cost of the bags in comparison to the traditional bags.