文档介绍：【英语四六级新题型练习】英语六级阅读理解之长篇阅读(附详解)
Paper--More than Meets the Eye
A) We are surrounded by so much paper and card that it is easy to forget just
plex it is. There are many varieties and grades of paper materials, and whilst
it is fairly easy to spot the varieties, it is far more difficult to spot the grades.
B) It needs to be understood that most paper and card is manufactured for a
specific purpose, so that whilst the corn-flake packet may look smart, it is clearly not
something destined for the archives. It is made to look good, but only needs a limited
life span. It is also much cheaper to manufacture than high grade card.
C) Paper can be made from an almost endless variety of cellulose-based material
which will include many woods, cottons and grasses or which papyrus is an example
and from where we get the word "paper". Many of these are very specialized, but the
preponderance of paper making has been from soft wood and cotton or rags, with the
bulk being wood-based.
Paper from Wood
D) In order to make wood into paper it needs to be broken down into fine strands.
Firstly by powerful machinery and then boiled with strong alkalies such as caustic
soda, until a fine pulp of cellulose fibers is produced. It is from this pulp that the final
product is made, relying on the bonding together of the cellulose into layers. That, in a
very small nutshell, is the essence of paper making from wood. However, the reality is
rather plicated. In order to give us our white paper and card, the makers will
add bleach and other materials such as china clay and additional chemicals.
E) A further problem with wood is that it contains a material that is not cellulose.
Something called lignin. This is essential for the tree since it holds the cellulose fibres
together, but if it is incorporated into the manufactured paper it presents archivists
with a problem. Lignin eventually breaks down and releases acid products into the
pape