แปลภาษาอังกฤษเป็นไทย ออนไลน์ แปลภาษา แปลข้อความ แปลบทความ แปลเอกสาร แปลประโยคอังกฤษเป็นไทยทั้งประโยค แปลเอกสารภาษาอังกฤษเป็นภาษาไทยทั้งประโยค แปลประโยคอังกฤษเป็นไทย แปลอังกฤษ แปลไทย ฟรี [Translate] English to Thai Translation Translate Translator , ภาษาอังกฤษ มีใช้ในประเทศออสเตรเลีย แคนาดา ไอร์แลนด์ นิวซีแลนด์ สหราชอาณาจักร สหรัฐอเมริกา ไลบีเรีย เบลีซ แอฟริกาใต้ อินเดีย
olymers are substances made up of recurring structural units, each of
which can be regarded as derived from a specific compound called a moanomer.
The number of monomeric units usually is large and variable, each sample of
a given polymer being characteristically a mixture of molecules with different
molecular weights. The range of molecular weights is sometimes quite narrow,
but is more often very broad. The concept of polymers being mixtures of molecules
with long chains of atoms connected to one another seems simple and
logical today, but was not accepted until the 1930's when the results of the
extensive work of I-I. Staudinger, who received the Nobel Prize in Chemistry
in 1953, finally became appreciated. Prior to Staudinger's work, polymers
were believed to be colloidal aggregates of small molecules with quite nonspecific
chemical structures.
The adoption of definite chemical structures for polymers has had farreaching
practical applications, because it has led to an understanding of
how and why the physical and chemical properties of polymers change with
the nature of the monomers from which they are synthesized. This means that
to a very considerable degree the properties of a polymer can be tailored to
particular practical applications. Much of the emphasis in this chapter will be
on how the properties of polymers can be related to their structures. This is
appropriate because we already have given considerable attention in previous
chapters to methods of synthesis of monomers and polymers, as well as to the
mechanisms of polymerization reactions.
The special technical importance of polymers can be judged by the fact
that half of the professional organic chemists employed by industry in the
United States are engaged in research or development related to polymers.