Silk, One of God's Many Wonders

Compiled by Mike Toler

 A recent article in the March-May 2001 issue of Creation Magazine gave many reasons why silk is a very difficult substance to reproduce. What follows is a brief discussion of what is going on in the current research into artificial silk manufacture.

Many people in this society have often seen the bulletproof vests that the police have taken to wearing with regularity, but perhaps have not thought about what is ‘bulletproofed’ and how it is manufactured. The material that is in today’s bulletproofed vests is the material known as Kevlar, a synthetic fiber which is ten percent stronger by weight than steel.

The strength of Kevlar lies in its chemical structure. It is spun as a liquid crystal, forming a rigid rod polymer, and when it is oriented properly, is very stiff. That particular characteristic plus the fact that it does not have a melting point (it decomposes before melting), gives it great flame retardant properties. This is also why it is used in airplanes and certain areas in autos to reduce the likelihood of a fire. Few people know that Kevlar is used in other areas besides bulletproof vests. Its bullet stopping capacity comes from its ability to flatten out on bullet impact, thereby absorbing the impact energy.

While Kevlar is the champion of manmade products, it is overshadowed in many ways by the spider web. Spider silk is stronger and more elastic than Kevlar. Dragline silk, the main support for a spiders web, is a hundred times stronger than steel, a cable of this silk a little thicker than a garden hose could support the weight of two full Boeing 737 aircraft. It can also stretch to 40% of its length, while the silk used in the web itself can stretch to over 200% of its length.

Spider silk owes its amazing strength and elasticity to its incredible complexity. Man-made fibers are usually just simple strands of material, but a silk fiber has a core surrounded by concentric layers of nanofibrils (tiny threads). Some layers contain nanofibrils aligned parallel to the axis, while other layers contain nanofibrils coiled like a spiral staircase. The coiled ones allow the silk to be stretched, because they simply straighten up rather than break. The nanofibrils themselves are very complicated, containing tiny protein crystals in an amorphous matrix of tangled protein chains. These nanocrystals contain electrical charges that stop the chains from slipping, so providing strength, while the amorphous material is rubbery and allows the fiber to stretch.

Some researches have tried to make silk artificially, but they always end up with a product half as strong as nature produces. The researchers believe that silk is made using liquid crystals using a process similar to the manufacture of Kevlar.

Spiders normally now use their webs for trapping insects and other prey. But some baby spiders catch pollen for food, providing a possible clue to a pre-fall function for the spider web.

Why is this so important? It is little known that Genghis Khan’s men actually used silk armor when they came out of the east, and that it was very effective. What today’s researchers are trying to do is develop body armor made of silk that would be both lighter and breath better than today’s Kevlar vests. The problem has always been to get enough silk for mass production as it takes many spiders working overtime to produce enough for a shirt, much less body armor.

A biotech firm has bio-engineered a herd of sheep so that the sheep produce silk in their milk and the silk can then be filtered out. At this time the herd has the potential to take the spiders out of the silk producing.  The potential is there for body armor that is light to carry, many times stronger than Kevlar, and yet will let enough air pass through that no police officer will get too hot and pull his vest off and thereby endanger his or her self.

All this from a creature that is a product of random chance------NOT

References

1.      Creation  23(2) March-May 2001

2.      The Spinners, New Scientist, 162(2183)

3.      How Spiders Make Their Silk, Discover 19(10)

4.      Spider Genes Reveal Flexible Design, Science 270(5457)

5.      Nature Australia 26(7)

6.      Pollen eating Spiders, Creation 22(3)

7.      Nature Bioterchnology article