When it comes to 3D printing, the sky is the limit. As 3D printing technology continues to advance, applications can be as far reaching as airplane and automobile parts to medical devices and even anatomically correct, biocompatible models. Although 3D printing technology is developing at a rapid pace, the technology itself is not new. It emerged in the 1980s as a means of creating rapid prototypes. In recent years the applications for 3D printed models have evolved with the available hardware, software, and printable materials. Evolving technology, paired with the creative and innovative minds of scientists, engineers, and physicians, has been the launching pad for developments within 3D printing technology specific to healthcare. One way 3D printing technology is poised to create better patient outcomes is in creating an anatomically and patient-specific models to aid in surgery and medical procedures. With the capability to 3D ...
Ever dream of being a knight? Putting on a lot of heavy armor (or armour) might be discouraging, but what if it were light and flexible?
The good news for contemporary knights is that a very strong, light, and flexible armor can be made from polymer fabric. The polymer structure of the fibers and their orientation relative to each other are directly related to the performance of the fabric armor.
The strongest fibers are made of ultra-high-molecular-weight polyethylene (UHMWPE), a highly-structured material of exceptional tensile strength. The strength comes from the length of aliphatic polymer chains (with molecular weight of 2-6 million Da), high degrees of crystallinity, and molecular alignment. Commercial UHMWPE fibers are known by names Dyneema and Spectra.
Dyneema fibers are used to make armored helmets, vests, and shields to protect against a wide range of ballistic threats, including handgun ammunition, knives, rifles, or high-speed fragments coming from makeshift bombs. It is used to make personal armor for soldiers, law enforcement officers, commercial pilots, and high-profile civilians, as well as vehicle armor for land, air, and sea transportation.
Dyneema fiber is lightweight, yet 15 times stronger than steel. The fibers also are used to make extra-strong, flexible, and water-resistant ropes, lines, and fabrics for fishing and sailing, and for extreme-sports attire. UHMWPE nets and air cargo containers provide both strength and weight advantages, reducing carbon footprint while increasing safety. UHMWPE polymer is also used as an inert, water-resistant, and strong medical implant material.
While the aliphatic polyethylene in UHMWPE polymer has a high degree of crystallinity, the aromatic polyesters with oriented liquid crystal domain composing the polymer fiber Vectran make it five times stronger than steel and 10 times stronger than aluminum.
According to “Material Benefits” in The Economist:
Vectran is also notable for its low ‘creep,’ or reluctance to stretch. It helps keep robots’ gestures precise when used in their cabling, for instance, and is woven into other materials to make stronger tapes, sails and slash-resistant butcher’s gloves. Lindstrand Technologies, a British maker of airships, recently switched from polyester to a Vectran-based fabric, even though it costs about 10 times as much. It has the advantage of being both lighter and tougher […]More recently, Vectran has been protecting British armoured vehicles from Russian-made rocket-propelled grenades, which use an explosion to propel a spike of copper through as much as 25cm of steel. A Vectran netting system, mounted on a light metal frame and wrapped around vehicles about 30cm from their surface, deforms the warhead tip in a way that prevents the spike from forming.
Other synthetic fibers exhibiting liquid-crystalline behavior include those made of aromatic polyamide (so called “aramid”) polymers, such as Kevlar, which have been used for body armor and other military applications for decades. More recently a new auxetic fabric Xtegra was designed, combining the high-tensile strength of Kevlar with the flexibility of the rubber-like polymer Hytrel. It has a unique ability to thicken when stretched, as auxetic materials have a property of becoming thicker perpendicular to the applied force due to their unique structural geometry. Xtegra™ won awards in the Global Security Challenge European Semi-finals in 2007 and 2009. Material design of Xtegra, as applied to blast mitigation, is explained in detail in a 10-minute video. The results are impressive, as described by The Economist:
Fragments of shrapnel from an explosion bounce off the fabric as it stretches and thickens to absorb their kinetic energy and then snaps back. In a test carried out by the British Ministry of Defense, five 1mm layers of Xtegra stopped shrapnel from a rocket-propelled grenade detonated 5 meters away. Adjusting the size and weaving patterns of the auxetic fiber can produce materials optimized for particular uses.
We all hope the day will come when we don’t need protection from each other. But for today, new polymer fabrics can help save lives in our less-then-perfect world.
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