Utilisation of Waste Plastic

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INTRODUCTION
Bitumen is a useful binder for road construction. Different grades of bitumen like 30/40, 60/70 and 80/ 100 are available on the basis of their penetration values. The steady Increase in high traffic intensity in terms of commercial vehicles, and the significant Variation in daily and seasonal temperature demand improved road characteristics. Any Improvement in the property of the binder is the needed.

Today the availability of the waste plastics is enormous, as the plastic materials have become part and parcel of daily life. They either get mixed with Municipal Solid Waste and/or thrown over land area. If not recycled, their present disposal is either by land filling or by incineration. Both the processes have certain impact on the environment. Under this circumstance, an alternate use for the waste plastics is also the needed. Thinner polythene carry bags are most abundantly disposed of wastes, which do not attract the attending rag pickers for collection for onward recycling, for lesser value. Again, these polythene/polypropylene bags are easily compatible with Bitumen at specified conditions. The waste polymer bitumen blend can be prepared and a study of the properties can throw more light on their use for road laying.

WASTE PLASTICS - AS BINDER AND MODIFIER:
Waste plastics (polythene carry bags, etc.) on heating soften at around 130°C. thermo gravimetric analysis has shown that there is no gas evolution in the temperature range of 130-180°C. Moreover the softened plastics have a binding property. Hence, the molten plastics materials can be used as a binder and/or they can be mixed with binder like bitumen to enhance their binding property. This may be a good modifier for the bitumen, used for road construction.

NEED FOR THE STUDY:
1) Disposal of waste plastic is a major problem
2) It is non-biodegradable
3) Burning of these waste plastic bags causes environmental pollution. 4) It mainly consists of low-density polyethylene
5) To find its utility in bituminous mixes for road construction 6) Laboratory performance studies were conducted on bituminous mixes. Laboratory studies proved that waste plastic enhances the property of the mix 7) Improvement in properties of bituminous mix provides the solution for disposal in an useful way

DEFINITION
WASTE PLASTICS - AS BINDER AND MODIFIER:
Waste plastics (polythene carry bags, etc.) on heating soften at around 130°C. Thermo gravimetric analysis has shown that there is no gas evolution in the temperature range of 130-180°C. Moreover the softened plastics have a binding property. Hence, the molten plastics materials can be used as a binder and/or they can be mixed with binder like bitumen to enhance their binding property. This may be a good modifier for the bitumen, used for road construction.

DIFFERENT TYPE OF WASTE PLASTIC (POLYMER) AND ITS
ORIGIN:
Type of waste plastic (polymer) origin
Low density polyethylene (LDPE): bags, sacks, bin lining and squeezable detergent bottles etc High density polyethylene (HDPE): bottles of pharmaceuticals, disinfectants,milk, fruit juices, bottle caps etc Polypropylene (PP): bottle cap and closures, film wrapping for biscuits, microwave trays for ready-made Meals etc. Polystyrene (PS): yoghurt pots, clear egg packs, bottle caps. Foamed Polystyrene: food trays, egg boxes, disposable cups,protective packaging etc Polyvinyl Chloride (PVC): mineral water bottles, credit cards, toys, pipes and gutters; electrical fittings, furniture, folders and pens; medical disposables; etc

CHARACTERIZATION OF WASTE PLASTICS:
THERMAL STUDY
Thermal behavior of the polymers namely PE, PP and PS is shows in Table 1. Table 1. Thermal Behavior of Polymers
Polymer| SolubilityWaterEPT*| Softening Tempin Deg. C| Productsreported| DecompositionTemp Deg. C| IgnitionTempDeg .C| PE| Ni| Nil| 100-120 | No gas| 270-350| >700|
PP| Nil| Nil| 140-160 | No gas| 270-300| >700|
PS| Nil | Nil| 110-140| No...
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