Plastics are polymers. Epoxy is a specific chemical means to produce a plastic.
A dictionary, and English lessons (which includes definitions of words like these) would serve you well.
TimOzone - 19-8-2007 at 21:24
"Resin" implies an incompletely polymerized material. For example, styrene is polymerized so as to achieve rather high conversion and medium molecular
weight. Then the polymerization is haulted. At his point the material is a viscous liquid which can be poured for casting, etc. The resulting
material can be re-initiated (benzoyl peroxide is common, think Bondo) at will to rapidly produce the final 99.9% conversion, yielding high molecular
weight "plastic" in a time span which is convenient. E.g. minutes rather than hours.
Epoxy resin contains your hexamethylene diamine:epichlorohydrin polymer at low to medium moelcular weight...plus some more monomer. When mixed with
the curing reagent (also containing the other monomer), you get plastic, quickly. The straight monomer-->plastic reaction takes too long, so, a
pre-polymerized resin is what they sell you.
Cheers,
O3Xenoid - 19-8-2007 at 21:43
Quote:
Originally posted by 12AX7
A dictionary, and English lessons (which includes definitions of words like these) would serve you well.
Tim
Yeah, except the dictionary definitions are a bit vague!
Plastic
any of a group of natural or synthetic organic materials which may be shaped when soft and then hardened, including many types of resins, resinoids,
polymers, cellulose derivitives, casein materials and proteins.
Resin
any of a class, of non-volatile, solid or semisolid organic substances obtained directly from certain plants as exudations or prepared by
polymerisation of simple molecules and used in the making of varnishes and plastics
Xenoidjokull - 20-8-2007 at 06:11
Hi!
I'll try to explain both terms based on fundamental definitions:
Polymer:
The word polymer is derived from classical Greek "poly" meaning “many” and "meres" meaning “parts.”
Thus a polymer is a large molecule (macromolecule) built up by the repetition of small chemical units.
Plastic:
This word is derived from greek "plastikos" meaning "molding".
Originally, the term was used as an adjective to indicate a material was capable of being ‘‘molded or shaped’’.
In the field of polymeric materials, a plastic is a material that contains as an essential ingredient one or more high polymers,
is solid in its finished state and, at some stage in its manufacture or processing into finished articles, can be shaped by flow.
However, this definition is supplemented by notes explaining that materials such as rubbers, textiles, adhesives, and paints, which may in some cases
meet this definition, are not considered to be plastics.
Resin:
This word is related to the greek "rhetine" refered to pine resin. The term resin is defined by ASTM D 883 as a solid or pseudosolid material, often
of high molecular weight, that exhibits a tendency to flow when subjected to stress, usually has a softening or melting range, and usually fractures
conchoidally.
A note appended to this definition explains that in a broad sense, the term is used to designate any polymer that is a basic material (or raw
material) for plastics. However, common uses of the term in the plastics industry do not always conform to this definition.
The term is also used for uncured fluid thermosetting materials, some chemically modified natural resins, and often synonymously with the terms
plastic and polymer.
The conclusion:
The terms plastic, resin, and polymer are somewhat synonymous, but resin and polymer most often denote the basic materials as polymerized, while the
term plastic or plastics encompasses compounds containing plasticizers, stabilizers, fillers, and other additives.
