On this day in science history: foam rubber was developed

In 1929, foam rubber was developed at the Dunlop Latex Development Laboratories in Birmingham. British scientist E.A. Murphy whipped up the first batch in 1929, using an ordinary kitchen mixer to froth natural latex rubber. His colleagues were unimpressed - until they sat on it. Within five years it was everywhere, on motorcycle seats, on London bus seats, Shakespeare Memorial Theatre seats, and eventually in mattresses.

In 1937 isocyanate based materials were first used for the formation of foam rubbers, after World War II styrene-butadiene rubber replaced many natural types of foam. Foam rubbers have been used commercially for a wide range of applications since around the 1940s. There are two types of foam in use today. One is flexible foam and the other is rigid foam. The flexible version of the foam is used in furniture, car seats, to insulate walls, and even in the very shoes that we wear. The rigid form of foam rubber is used in insulating buildings, appliances like freezers and refrigeration trucks. 

Foam rubber mattress [Public domain], via Wikimedia Commons

So, how is foam rubber manufactured? Rates of polymerization can range from many minutes to just a few seconds. Fast reacting polymers feature short cycle periods and require the use of machinery to thoroughly mix the reacting agents. Slow polymers may be mixed by hand, but require long periods on mixing. As a result industrial application tends to use machinery to mix products. Product processing can range from a variety of techniques including, but not limited to spraying, open pouring, and molding.

• Material preparation - Liquid and solid material generally arrive on location via rail or truck, once unloaded liquid materials are stored in heated tanks. When producing slabstock  typically two or more polymers streams are used.
• Mixing - Open pouring, better known as continuous dispensing is used primarily in the formation of rigid, low density foams. Specific amounts of chemicals are mixed into a mixing head, much like an industrial blender. The foam is poured onto a conveyor belt, where it then cures for cutting.
• Curing and Cutting - After curing on the conveyor belt the foam is then forced through a horizontal band saw. This band saw cuts the pieces in a set size for the application. General contracting uses 4’x12’x2’’.
• Further processing - Once cut and cured the slabstock can either be sold or a lamination process can be applied. This process turns the slabstock into a rigid foam board known as boardstock. Boardstock is used for metal roof insulation, oven insulation, and many other durable goods.

Unfortunately, because of the variety in polyurethane chemistries, it is difficult to recycle foam materials using a single method. Reusing slab stock foams for carpet backing is how the majority of recycling is done. This method involves shredding the scrap and bonding the small flakes together to form sheets. Other methods involve breaking the foam down into granules and dispersing them into a polyol blend to be molded into the same part as the original. The recycling process is still ever developing for foam rubber and the future will hopefully unveil new and easier ways for recycling.

For more information, visit:-

https://todayinsci.com/7/7_03.htm

https://en.wikipedia.org/wiki/Foam_rubber
http://www.prlabs.co.uk/lab-supplies.php?N=balls-rubber-20mm-&Id=46943

On this day in science – the rubber fire hose was patented

In 1821, a fire hose of cotton web lined with rubber was patented by James Boyd of Boston, Mass. He invented it to replace riveted leather hose. Leather hose had many drawbacks, including drying out, cracking and bursting from excessive pressure. The introduction of rivets (1807), to replace stitching, had allowed higher pressures and greater delivery of water on the fireground. The improved hose now was 40 to 50 feet in length and weighed more than 85 pounds with the couplings. Hose oilers were developed to keep the leather supple and pliable. Various types of oils and other substances were used to keep the hose in shape. By 1871, the Cincinnati Fire Department was using the B.F. Goodrich Company's new rubber hose reinforced with cotton ply.

Indoor fire hose with a fire extinguisher, by Raysonho @ Open Grid Scheduler / Grid Engine (Own work) [CC0], via Wikimedia Commons

Modern fire hoses use a variety of natural and synthetic fabrics and elastomers in their construction. These materials allow the hoses to be stored wet without rotting and to resist the damaging effects of exposure to sunlight and chemicals. Modern hoses are also lighter weight than older designs, and this has helped reduce the physical strain on firefighters. Various devices are becoming more prevalent that remove the air from the interior of fire hose, commonly referred to as fire hose vacuums. This process makes hoses smaller and somewhat rigid, thus allowing more fire hose to be packed or loaded into the same compartment on a fire fighting apparatus.

There are several types of hose designed specifically for the fire service. Those designed to operate under positive pressure are called discharge hoses. They include attack hose, supply hose, relay hose, forestry hose, and booster hose. Those designed to operate under negative pressure are called suction hoses.

For more information visit:-

https://todayinsci.com/5/5_30.htm

https://en.wikipedia.org/wiki/Fire_hose

http://www.prlabs.co.uk/lab-supplies.php?N=balls-rubber-20mm-&Id=46943