Development of composite materials results in superstrong yet flexible equipment for a wide range of uses.
by Wendy Elliman
A paramedic runs to the scene of a horrific accident. Unstrapping a rolled-up stretcher from his waist, he moves quickly: the stretcher, far from needing a heavy frame across his back, can be held in one hand, and when needed snaps into a man-sized pallet, easily carrying up to 500 lbs (227 kgs.) He finds the wounded woman and eases her on to the stretcher, when there is another cry. He reaches for the second stretcher at his waist - and still has a third in reserve.
This paramedic is living neither in a dream nor in the future. The stretcher exists. Weighing (and costing) half of the traditional stretcher, it bears 100 times its own weight and rolls up so small that three may be carried at once around the waist.
It is one result of the relatively new science of composite materials, the combining of two or more substances to produce a new material, with properties superior to its constituents. Wood, bone and muscle are natural composites, and traditional building materials, like wattle and daub, are examples of 'large-scale' composites. The modern science of composite materials, however, is on the microscopic level. It 'glues' fibers of glass, carbon or a synthetic material into a ceramic, metal or polymer 'frame'. The result: tough, lightweight materials, stronger than concrete or steel, which can support heavy structures and survive under extreme conditions.
The lightweight stretcher, developed in the Entrepreneurial Incubator at the Technion - Israel Institute of Technology, is made of a mixture of rubber-like synthetic materials, metals and metal composites. "Its collapsible lightweight support beams fold along their weaker side, but are rigid when unfolded," explains mechanical engineer Prof. Yehiel Weinstein. "We call it 'Flexibeam technology'."
Because all mechanical structures use support beams, Flexibeam has a wide range of potential applications, such as firefighters' ladders, folding beds, shelving, pergolas, oars, tents, scaffolding, antennae, electric poles, traffic signs and solar panels.
Flexibeam is one among a growing number of new materials created in Israel. Another is polyeitan, which is made from polyethylene, the material used for making plastic bags. Resembling hard white pipes or boards, polyeitan could be used to replace human hips, build submarine bodies and protect radar antennae.
"Polyeitan is light, strong, resists rust and low temperatures and is impervious to acids and external impact, while remaining penetrable by radar and sonar, because its fibers and frame are made from the same substance," says its inventor, Technion chemical engineer, Prof. Yachin Cohen.
Composites based on ceramics are also being developed. One combines molten metal alloys with ceramics, "producing a compound resistant to both abrasion and heat," explains Prof. Moshe Daniel of Ben-Gurion University of the Negev. Another, being developed by materials engineer Dr. Wayne Kaplan at the Technion, infiltrates porous ceramic with liquid metal and reinforces it with microscopic-sized metal particles. The resulting materials will be strong enough for spacecraft hulls and oil-drilling platforms, while light enough to armor cars and create flak jackets.