Synthetic Paper from Plastics
- Published: October 01, 2000, By Balasubramanian K. and D. D. Kale, Univ. of Mumbai, Matunga, Mumbai 400 019, India
Application: A mixture of linear low density polyethylene and polystyrene with 40% filler consisting of 80% dolomite and 20% talc is very promising for synthetic paper uses.
Synthetic paper and paper-like products made from polymers have tremendous application potential. For synthetic paper, using commodity polymers such as polyethylene, polypropylene, or polyvinyl chloride is always attractive due to the ready availability, low cost, and versatile processing possibilities of the polymers. Earlier work has described the process of making synthetic paper from plastics. This includes high loading with fillers.
Plastic bags form a major fraction of municipal waste. They offer a good source of inexpensive raw material that could be very suitable to develop a synthetic paper-like product. This work examines mixtures of linear low density polyethylene (LLDPE) with high density polyethylene (HDPE), waste plastic bags, polystyrene (PS), and high impact polystyrene (HIPS) with dolomite (D) and talc (T) fillers.
Results
All the films had paper-like appearance. Examining the effect of filler, dolomite gave considerable reduction in tensile strength. Incorporation of fillers may weaken polyethylene film structure that may be desirable for synthetic paper applications. Adding HDPE decreased tear strength and falling dart impact. Addition of PS and HIPS causes the properties of LLDPE films to approach the mechanical properties of paper.
With higher filler levels, the water vapor permeability of LLDPE increased. This is probably due to more porosity in the film from filler loading.
Heat seal temperature increased slightly and peel strength decreased with higher levels of dolomite. Addition of waste plastic bags gave higher heat seal temperature and greater peel strength. Examination of melt flow index showed that the range of this property for all the compositions was suitable for film blowing.
Conclusions
Addition of fillers reduces the tensile strength, dart impact, and folding endurance of LLDPE to approach the behavior of paper. Use of mixed fillers and incompatible polymers helps to attain the properties of paper. The tensile strength of most compositions in this study is slightly less than that of paper. Using a small amount of crosslinking agent such as dicumyl peroxide may help improve this property. Waste plastic bags can have successful use to develop synthetic paper. Incorporation of mixed fillers and a small amount of incompatible polymer to any film forming polymer such as polyethylene or polypropylene requires further study for synthetic paper applications.
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