For Brent English, the question is not paper or plastic. The question is paper and plastic. English puts the two recycled materials together to make plastic lumber at the U.S. Department of Agriculture's Forest Products Laboratory in Madison, Wis., where he works as an industrial specialist. Still undergoing testing under laboratory conditions, the process is about a year away from regular commercial use.
``We are starting to see a new class of materials,'' English said. ``We are not going to reinvent the world, but you are going to see broader and broader use of this process.''
His technique mixes polypropylene, low and high density polyethylene, polystyrene or PVC with paper. English discussed the process in a presentation at the Society of Plastics Engineers second annual recycling conference in Akron in late October.
The ink on the paper gives the plastic a dark gray appearance, English said, and the fiber in the paper increases both the stiffness and strength of the lumber.
English has tested the process using varying grades of paper, but said most interest focuses on newspaper and mixed office paper because of cost factors.
``Those are the paper grades that historically are the cheapest and most readily available,'' he said.
The paper needs to be under $50 per ton to be economically viable, English said.
Paper processors are interested in the process because of the potential for an additional market for sometimes hard-to-move material.
Plastic lumber manufacturers are interested because it reduces their costs.
The technique requires that the paper be processed through a hammermill and then dried. Temperatures that melt plastic boil water in the paper and create steam that causes foaming, English said.
But using processed paper presents at least one problem, English said - the light and fluffy paper is hard to feed into the machine.
While a 50-percent paper, 50-percent plastic mix is the practical upper limit for the process, some applications can use up to 70 percent paper, according to English.
Aeolian Enterprises Inc., a plastic lumber manufacturer in Latrobe, Pa., is experimenting with making pallets with the plastic-paper mix.
``Our lumber is hollow, and we are looking at using mix as a core,'' said Bill McClintic, president of Aeolian.
The cores are 30-40 percent paper, and the balance is plastic with some air to make a low-density - almost foam - core, McClintic said. The paper does not have to be as dry as in English's process because the steam-created foaming further decreases the weight of the lumber.
The technique can reduce a pallet's weight by 30-40 percent, McClintic said.
``The food industry is interested in the pallets because they often have to be moved around by hand,'' he said.