Sugar was not the only plant that changed society and motivated slave trade during 18 century,cotton plantation also need extensive manual labors provide by enslaved Africans,and the great demand for cotton motivated the industrial revolution during eighteen century.If we define sugar as fuel of industrial revolution,then cotton must be the catalyst of industrial revolution.
Cotton was cultivated in India,Pakistan,Mexico and Peru five thousands years ago,and it was known by Europeans around 300 B.C. Cotton was not able to be grown in regions of Europe,because Europe did not have conditions that cotton required.But people could still get cotton products by importing cotton from other country or from their colonies.
Lancashire,in England,was famous for its cotton manufacture.Its damp climate make cotton fibers stick together which makes cotton fibers less easily to break.Besides,Lancashire had available land to build mills and houses for workers to live in.It was until eighteenth century when a series of cotton-making machines were invented such as spinning jenny and spinning throstle,which greatly improved efficiency of making cotton products.At that time,these machines were powered by human,the invention of steam engine set human free from heavy works,and steam engine was the main power source of cotton-making machines.
Cotton and other plant fibers consist of over 90 percent cellulose,which is the polymer of glucose.Again,there are two types of glucose,αglucose and βglucose，the difference is only the position of OH group.For αglucose,OH is above carbon number one.As for αglucose,OH is below carbon number one.These two types of glucose show different properties due to this small difference.βglucose（OH above）has a structural function and α glucose has a storage function
Cellulose is made of many individual glucose that joined together.For example,polysaccharide is made of glucose units that are joined to each through condensation reaction.In condensation reaction,carbon number one on a glucose unit and carbon number four on another glucose unit are bonded together with a water molecule comes out,forming a O linkage.Each end of the glucose molecule joins to another,that is how polysaccharide formed.Furthermore,cellulose tend to pack,forming a cellulose bundle.and these bundles twist together again,becoming what we can see through our naked eyes:cotton.
Chitin,another structural polysaccharide,polysaccharide is mostly found in the shell of crustaceans such as crabs,shrimps,and lobsters.And it is also a β polysaccharide(OH above),it differs from cellulose at carbon number two,where OH group is replace by (NHCOCH3).
By the 1830s,cellulose was found that it can dissolve in concentrated nitric acid,becoming a highly flammable and explosive white powder.It was believed by Friedrich Schonbein that cellulose can replace gunpowder due to its flammable character.Friedrich made an experiment at his home,he used his wife’s cotton apron and spilled some acid on it,then he put his wife’s cotton apron near the stove.Bang,the cotton apron exploded.He name his newly discovered material guncotton(or schiessbaumwolle).By examining composition of this new material,the OH group in cellulose is replaced by NO2 group,forming what we call it nitrocellulose.He also established factories to manufacture guncotton.But he failed at last,because guncotton is extremely unstable,it could explode if it was not kept properly.A number of his factor were destroyed by explosions.It was not until 1860s,proper methods were found to keep guncotton safely. Nowadays,nitrocelluloses are used in many area.For example celluloid (first plastic) and collodion(fused in early photography),
Humans and other mammal do not have enzyme to break down βlinkage ，so humans and other mammals are unable to digest β polysaccharide（structural）.Thankfully,there some kinds of microorganisms living in livestocks' body that can allow their hosts break down cellulose into glucose unit.
However,humans do have the enzyme to break down anαlinkage,which exists in αpolysaccharides(storage).We can find αpolysaccharides in starch which is found in plant roots,tuber and seeds.Starch consists of two slightly different polysaccharide molecules: amylose(20-30 percent) and amylopectin(70-80 percent).They both have αlinkages and same shapes,the only difference is that amylopectin has cross linkages between carbon number one of one glucose unit and carbon number six of another glucose unit,and the cross linkage occurs every twenty to twenty-five glucose units.Also,amylose tend to form into a shape of a helix,so water is easy to penetrate into amylose,that is why starch is water soluble.
The storage polysaccharide in animal is called glycogen. Glycogen(in animal) and amylopectin(in plant) are very similar.Unlike amylopectin,glycogen tend to form a cross linkage every ten glucose units instead of twenty.In this way,more chain branches can be formed and when energy is needed,these branches can be removed at same time and provide energy at same time,that is why glycogen can provide energy much quicker than amylopectin.Plants do not need sudden bursts of energy,so amylopectin fit them better than glycogen.
Cellulose presents in our society in many forms and area:explosive,movie,photography.We can almost find cellulose everywhere in our life.
Friedrich Schonbein experiment is a great example of serendipity how he accidentally spilled acid and the first thing he grabbed was his wife's apron who knew he would stumble upon nitrocellulose.
回复删除I thought it was really interesting that cellulose was the start of the photography and film industry, because I had no idea of that role in history. Is just one more example of how much this molecules have affected our world.
回复删除I, too found it interesting that cellulose was the start of photography and films because I am so interested in both. I had no idea that cellulose would be present in both of those.
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