|
Acid
An acid
(often represented by the generic formula HA
[H+A−]) is traditionally considered any chemical
compound that, when dissolved in water, gives a
solution with a hydrogen ion activity greater
than in pure water, i.e. a pH less than 7.0.
That approximates the modern definition of
Johannes Nicolaus Bronsted and Martin Lowry, who
independently defined an acid as a compound
which donates a hydrogen ion (H+) to another
compound (called a base). Common examples
include acetic acid (in vinegar) and sulfuric
acid (used in car batteries). Acid/base systems
are different from redox reactions in that there
is no change in oxidation state. Acrylic may
refer to: chemical compounds that contain the
acryl group derived from acrylic acid.
Acrylic
Poly(methylmethacrylate) (PMMA) poly(methyl
2-methylpropenoate) is a thermoplastic and
transparent plastic. Chemically, it is the
synthetic polymer of methyl methacrylate. It is
sold by the trade names Plexiglas, Vitroflex,
Limacryl, R-Cast, Per-Clax, Perspex, Plazcryl,
Acrylex, Acrylite, Acrylplast, Altuglas,
Polycast, Oroglass, Optix and Lucite and is
commonly called acrylic glass, simply acrylic,
perspex or plexiglas. Acrylic, or acrylic fiber,
can also refer to polymers or copolymers
containing polyacrylonitrile. The material was
developed in 1928 in various laboratories and
was brought to market in 1933 by Rohm and Haas
Company. PMMA is often used as an alternative to
glass, and in competition with polycarbonate
(PC). It is often preferred because of its
moderate properties, easy handling and
processing, and low cost, but behaves in a
brittle manner when loaded, especially under an
impact force. To produce 1 kg of PMMA, about 2
kg of petroleum is needed. PMMA ignites at 460°C
and burns completely to form only carbon dioxide
and water.
Alkaline
In
chemistry, an alkal is a basic, ionic salt of an
alkali metal or alkaline earth metal element.
Alkalis are best known for being bases that
dissolve in water. Bases are compounds with a pH
greater than 7. The adjective alkaline is
commonly used in English as a synonym for base,
especially for soluble bases. This broad use of
the term is likely to have come about because
alkalis were the first bases known to obey the
Arrhenius definition of a base and are still
among the more common bases. Since
Bronsted-Lowry acid-base theory, the term alkali
in chemistry is normally restricted to those
salts containing alkali and alkaline earth metal
elements.
return to top
Catheter
In medicine a catheter is a tube that can be
inserted into a body cavity, duct or vessel.
Catheters thereby allow drainage or injection of
fluids or access by surgical instruments. The
process of inserting a catheter is
catheterization. In most uses a catheter is a
thin, flexible tube: a "soft" catheter; in some
uses, it is a larger, solid tube: a "hard"
catheter.
Chamber
The entire Parylene process is generally carried
out in a closed system under constant negative
pressure. Such closed system may incorporate
separate chambers for the vaporization,
pyrolysis, and deposition steps of the process,
with such chambers being connected by way of
appropriate plumbing or tubular connections.
Conformal Coating
Conformal coating material is applied to a
surface to act as protection against moisture,
dust, chemicals, and temperature extremes. This
type of coating "conforms" to the applied
surface with an exact thickness of film 3
microns thick.
Dimer
A dimer is a chemical or biological entity
consisting of two subunits called monomers,
which are held together by either intramolecular
forces (covalent bonds) or weaker intermolecular
forces.
return to top
Elastomer
Elastomeric
An Elastomer is a polymer with the property
of elasticity. The term, which is derived
from elastic polymer, is often used
interchangeably with the term rubber, and is
preferred when referring to vulcanisates.
Each of the monomers which link to form the
polymer is usually made of carbon, hydrogen,
oxygen and/or silicon. Elastomers are
amorphous polymers existing above their
glass transition temperature, so that
considerable segmental motion is possible.
At ambient temperatures rubbers are thus
relatively soft (E~3MPa) and deformable.
Their primary uses are for seals, adhesives
and molded flexible parts.
Environment
The biophysical environment is the symbiosis
between the physical environment and the
biological life forms within the
environment, and include all variables that
comprise the Earth's biosphere. The
biophysical environment can be divided into
two categories: the natural environment and
the built environment, with some overlap
between the two. Following the industrial
revolution, the built environment has become
an increasingly significant part of the
Earth's environment.
Epoxy
In chemistry, epoxy or polyepoxide is a
thermosetting epoxide polymer that cures
(polymerizes and crosslinks) when mixed with
a catalyzing agent or hardener. Most common
epoxy resins are produced from a reaction
between epichlorohydrin and bisphenol-A. The
first commercial attempts to prepare resins
from epichlorohydrin were made in 1927 in
the United States. Credit for the first
synthesis of bisphenol-A-based epoxy resins
is shared by Dr. Pierre Castan of
Switzerland and Dr. S.O. Greenlee of the
United States in 1936. Dr. Castan's work was
licensed by Ciba, Ltd. of Switzerland, which
went on to become one of the three major
epoxy resin producers worldwide. Ciba's
epoxy business was spun off and later sold
in the late 1990s and is now the advanced
materials business unit of Huntsman
Corporation of the United States. Dr.
Greenlee's work was for the firm of
Devoe-Reynolds of the United States.
Devoe-Reynolds, which was active in the
early days of the epoxy resin industry, was
sold to Shell Chemical (now Hexion, formerly
Resolution Polymers and others).
return to top
Flight
Flight is the process by which an object
moves either through the air, or
movement beyond earth's atmosphere (as
in the case of spaceflight), by
aerodynamically generating lift,
propulsive thrust or aerostatically
using buoyancy, or by simple ballistic
movement.
Friction
Friction is
the force resisting the relative lateral
(tangential) motion of solid surfaces,
fluid layers, or material elements in
contact. It is usually subdivided into
several varieties: Dry friction resists
relative lateral motion of two solid
surfaces in contact. Dry friction is
also subdivided into static friction
between non-moving surfaces, and kinetic
friction (sometimes called sliding
friction or dynamic friction) between
moving surfaces. Lubricated friction[1]
or fluid friction[2][3] resists relative
lateral motion of two solid surfaces
separated by a layer of gas or liquid.
Fluid friction is also used to describe
the friction between layers within a
fluid that are moving relative to each
other.[4][5] Skin friction is a
component of drag, the force resisting
the motion of a solid body through a
fluid. Internal friction is the force
resisting motion between the elements
making up a solid material while it
undergoes deformation.[5]
Green
Chemicals normally
associated with being environmentally
friendly by being biodegradable.
Hydrochloric
Hydrochloric acid is the solution of
hydrogen chloride (HCl) in water. It is a
highly corrosive, strong mineral acid and
has major industrial uses. It is found
naturally in gastric acid. Historically
called muriatic acid or spirits of salt,
hydrochloric acid was produced from vitriol
and common salt. The alchemist Jabir ibn
Hayyan first formally described it in the
eighth century. During the Middle Ages, it
was used by alchemists in the quest for the
philosopher's stone, and later by European
scientists including Glauber, Priestley, and
Davy in their scientific research. With
major production starting in the Industrial
Revolution, hydrochloric acid is used in the
chemical industry as a chemical reagent in
the large-scale production of vinyl chloride
for PVC plastic, and MDI/TDI for
polyurethane. It has numerous smaller-scale
applications, including household cleaning,
production of gelatin and other food
additives, descaling, and leather
processing. About 20 million metric tons of
hydrochloric acid are produced annually.
return to top
I,
J, K and
L
Lubricity
Lubricity is the
measure of the reduction in friction of a
lubricant. The study of lubrication and
mechanism wear is called tribology.
return to top
M
Micron
A micron is equal to one millionth of a meter,
or about a tenth of the size of a droplet of
mist or fog. It is particulate smaller than the
naked eye can see. A micron is 1/25,000th of an
inch. A human hair is about 150 micros; the
smallest thing that can be seen with the naked
eye is about 10 microns. It is the largest
particles, above 5.0 microns, that cause
equipment problems and are what most filters are
able to catch. However, 98% of the particles in
the air are smaller than 1.0 micron. These
"sub-micron" particles are not caught by most
filters and get through our bodies' natural
defenses when inhaled. In technical terms, 1000
microns is equal to 1 mm. Human hair is 60 to 80
microns and the smallest visible object is about
40 microns across. 1 micron = 0.03937007874 mil
MIL
A United States Defense Standard, often called a
military standard, "MIL-STD", "MIL-SPEC", or
(informally) "MilSpecs", is used to help achieve
standardization objectives by the U.S.
Department of Defense. Standardization is
beneficial in achieving interoperability,
ensuring products meet certain requirements,
commonality, reliability, total cost of
ownership, compatibility with logistics systems,
and similar defense-related objectives
[1].Defense Standards are also used by other
non-Defense government organizations, technical
organizations, and industry. This article
discusses definitions, history, and usage of
Defense Standards. Related documents, such as
Defense Handbooks and Defense Specifications are
also addressed.
Moisture
Moisture generally refers to the presence of
water, often in trace amounts. The moisture
content is often an important aspect of various
foodstuffs including cheese and many dried goods
such as tea where excess moisture can promote
bacterial growth, decay, molding, or rotting
over time. Excessive moisture is usually
undesirable and can also cause rot in wood or
other organic material, corrosion in metals, and
electrical short circuits. Many home and
business owners go to great pains to prevent
these effects. Many products are sold to prevent
this. Some foodstuffs and other packaged
products come with desiccators, often made of
silicon oxide, to absorb moisture. In skin,
leather, and wood, moisture can also refer to
natural oils. Moisture is also sometimes used to
refer to the liquid form of solvents other than
water, especially when present in a solid.
Moisture is also used to refer to any type of
precipitation.
Monomer
Monomer is a small molecule that may become
chemically bonded to other monomers to form a
polymer.
N,
O and
P
Paraxylylene
The present invention provides a new class of
precursors for forming an improved diamond-like
carbon coating on a work piece. The precursors
of the present invention are paraxylylenes,
preferably dimers of paraxylylene, which are
solid at room temperature and which will
vaporize, pyrolize to substantially monomeric
form, condense onto a work piece, and
spontaneously polymerize to form a "parylene"
film which is free of precursor droplets and
absorbed water. Upon bombardment with an ion
beam, the parylene film is converted into a
uniform, pinhole-free DLC coating.
Pitch
A measure of distance between leads from an
integrated circuit
Plastic
Plastic is the general common term for a wide
range of synthetic or semi-synthetic organic
solid materials suitable for the manufacture of
industrial products. Plastics are typically
polymers of high molecular weight, and may
contain other substances to improve performance
and/or reduce costs. The word derives from the
Greek (plastikos), "fit for molding", from
(plastos) "molded" [1] [2]. It refers to their
malleability, or plasticity during manufacture,
that allows them to be cast, pressed, or
extruded into an enormous variety of shapes—such
as films, fibers, plates, tubes, bottles, boxes,
and much more. The common word "plastic" should
not be confused with the technical adjective
"plastic", which is applied to any material
which undergoes a permanent change of shape (a
"plastic deformation") when strained beyond a
certain point. Aluminum, for instance, is
"plastic" in this sense, but not "a plastic" in
the common sense; while some plastics, in their
finished forms, will break before deforming —
and therefore are not "plastic" in the technical
sense.
Polymer
A polymer is a large molecule (macromolecule)
composed of repeating structural units typically
connected by covalent chemical bonds. While
polymer in popular usage suggests plastic, the
term actually refers to a large class of natural
and synthetic materials with a variety of
properties and purposes. Polypropylene: IUPAC
name [show] Poly(propane-1,2-diyl) Except where
noted otherwise, data are given for materials in
their standard state at 25 °C, 100 kPa).
Well-known examples of polymers include plastics
and proteins. A simple example is polypropylene,
whose repeating unit structure is shown at the
right. However, polymers are not just limited to
having predominantly carbon backbones, elements
such as silicon form familiar materials such as
silicones, examples being silly putty and
waterproof plumbing sealant. The backbone of DNA
is in fact based on a phosphodiester bond.
Natural polymer materials such as shellac and
amber have been in use for centuries.
Biopolymers such as proteins and nucleic acids
play crucial roles in biological processes. A
variety of other natural polymers exist, such as
cellulose, which is the main constituent of wood
and paper. The list of synthetic polymers
includes Bakelite, neoprene, nylon, PVC,
polystyrene, polyacrylonitrile, PVB, silicone,
and many more. Polymers are studied in the
fields of polymer chemistry, polymer physics,
and polymer science.
Potting
In electronics, potting is a process of filling
a complete electronic assembly with a solid
compound for resistance to shock and vibration,
and for exclusion of moisture and corrosive
agents. Thermosetting plastics are often used.
Most circuit board assembly houses coat
assemblies with a layer of transparent conformal
coating rather than potting. Conformal coating
gives most of the benefits of potting, and is
lighter and easier to inspect, test, and repair.
When potting a circuit board that uses
surface-mount technology, Potting Solutions
recommends using low Tg potting compounds such
as polyurethane or silicone, because high Tg
potting compounds may break solder bonds as they
harden and shrink at low temperatures.
return to top
Rectifier
A rectifier is an electrical device that
converts alternating current (AC) to direct
current (DC), a process known as
rectification. Rectifiers have many uses
including as components of power supplies
and as detectors of radio signals.
Rectifiers may be made of solid state
diodes, vacuum tube diodes, mercury arc
valves, and other components. A device which
performs the opposite function (converting
DC to AC) is known as an inverter. When only
one diode is used to rectify AC (by blocking
the negative or positive portion of the
waveform), the difference between the term
diode and the term rectifier is merely one
of usage, i.e., the term rectifier describes
a diode that is being used to convert AC to
DC. Almost all rectifiers comprise a number
of diodes in a specific arrangement for more
efficiently converting AC to DC than is
possible with only one diode. Before the
development of silicon semiconductor
rectifiers, vacuum tube diodes and copper
(I) oxide or selenium rectifier stacks were
used. Early radio receivers, called crystal
radios, used a "cat's whisker" of fine wire
pressing on a crystal of galena (lead
sulfide) to serve as a point-contact
rectifier or "crystal detector". In gas
heating systems flame rectification can be
used to detect a flame. Two metal electrodes
in the outer layer of the flame provide a
current path and rectification of an applied
alternating voltage, but only while the
flame is present.
Refraction
Index of Refraction: The refractive index
(or index of refraction) of a medium is a
measure for how much the speed of light (or
other waves such as sound waves) is reduced
inside the medium. For example, typical
soda-lime glass has a refractive index of
1.5, which means that in glass, light
travels at 1 / 1.5 = 0.67 times the speed of
light in a vacuum. Two common properties of
glass and other transparent materials are
directly related to their refractive index.
First, light rays change direction when they
cross the interface from air to the
material, an effect that is used in lenses.
Second, light reflects partially from
surfaces that have a refractive index
different from that of their surroundings.
Resistance
Electrical resistance, a measure of the
degree to which an object opposes an
electric current through it.
return to top
Silicone
Silicones are largely inert compounds with a
wide variety of forms and uses. Typically
heat-resistant, nonstick, and rubberlike, they
are frequently used in cookware, medical
applications, sealants, lubricants, and
insulation. Silicones are polymers that include
silicon together with carbon, hydrogen, oxygen,
and sometimes other chemical elements. One of
the most common uses is holding glass together
(e.g., in aquariums).
SMT
Surface-mount technology (SMT) is a method for
constructing electronic circuits in which the
components (SMC, or Surface Mounted Components)
are mounted directly onto the surface of printed
circuit boards (PCBs). Electronic devices so
made are called surface-mount devices or SMDs.
In the industry it has largely replaced the
through-hole technology construction method of
fitting components with wire leads into holes in
the circuit board. An SMT component is usually
smaller than its through-hole counterpart
because it has either smaller leads or no leads
at all. It may have short pins or leads of
various styles, flat contacts, a matrix of
solder balls (BGAs), or terminations on the body
of the component.
Spec
In engineering, manufacturing, and business, it
is vital for suppliers, purchasers, and users of
materials, products, or services to understand
and agree upon all requirements. A specification
is a type of a standard which is often
referenced by a contract or procurement
document. It provides the necessary details
about the specific requirements. Specifications
may be written by government agencies, standards
organizations (ASTM, ISO, CEN, etc), trade
associations, corporations, and others. A
product specification does not necessarily prove
the product to be correct. Just because an item
is stamped with a specification number does not,
by itself, indicate that the item is fit for any
particular use. The people who use the item
(engineers, trade unions, etc) or specify the
item (building codes, government, industry, etc)
have the responsibility to consider the
available specifications, specify the correct
one, enforce compliance, and use the item
correctly. Validation of suitability is
necessary. An example of a US Federal
specification is FIPS-PUB 159, Detail
Specification for 62.5-μm Core diameter/125-μm
Cladding Diameter Class Ia Multimode Optical
Fibers. (Source: from Federal Standard 1037C and
from MIL-STD-188)
return to top
Torr
Unit of pressure defined as 1/760 of an
atmosphere. It was named after Evangelista
Torricelli, an Italian physicist and
mathematician who discovered the principle of
the barometer in 1644
Urethane
Are a group of organic compounds sharing a
common functional group with the general
structure - NH(CO)O -. Carbonates are esters
of carbamic acid, Nh3COOH, an unstable
compound. Since carbamic acid contains a
nitrogen attached to a carboxyl group, it is
also an amide. Therefore, carbamate esters
may have alkyl or aryl groups substituted on
the nitrogen, or the amide function. For
example, ethyl carbamate (trivial name
"urethane"), is unsubstituted, whereas ethyl
N–methylcarbamate has a methyl group
attached to the nitrogen (see methyl
isocyanate for formation of
N-methylcarbamates).
Vacuum
Vacuum is a volume of space that is
essentially empty of matter, such that its
gaseous pressure is much less than
atmospheric pressure.[1] The word comes from
the Latin term for "empty," but in reality,
no volume of space can ever be perfectly
empty. A perfect vacuum with a gaseous
pressure of absolute zero is a philosophical
concept that is never observed in practice.
Physicists often discuss ideal test results
that would occur in a perfect vacuum, which
they simply call "vacuum" or "free space" in
this context, and use the term partial
vacuum to refer to real vacuum. The Latin
term in vacuo is also used to describe an
object as being in what would otherwise be a
vacuum. The quality of a vacuum refers to
how closely it approaches a perfect vacuum.
The residual gas pressure is the primary
indicator of quality, and is most commonly
measured in units called torr, even in
metric contexts. Lower pressures indicate
higher quality, although other variables
must also be taken into account. Quantum
theory sets limits for the best possible
quality of vacuum, predicting that no volume
of space can be perfectly empty. Outer space
is a natural high quality vacuum, mostly of
much higher quality than can be created
artificially with current technology. Low
quality artificial vacuums have been used
for suction for many years.
return to top
W,
X,Y
XY
Parylene is the trade name for a variety of
polyxylylene polymers marketed by several
providers, including Kisco Conformal Coating,
LLC[1], Para Tech Coating, Inc.[2], Specialty
Coating Systems, Inc.[3], Parylene Coating
Services and others. Parylene N is a polymer
manufactured from di-p-xylylene, a dimer
synthesized from p-xylylene. Di-p-xylylene, more
properly known as [2.2]paracyclophane, is made
from p-xylylene in several steps involving
bromination, amination and elimination.
ZEROVOC
Zerovoc is a water-based, solvent free, super
hydrophobic, self-reactive siliconate HYBRID
protective water sealer. I is formulated to
deeply penetrate and chemically react within the
treated material on a molecular level. Because
of the unique cross-linking and symbiotic
relationship of the components contained in this
compound, this chemical reaction forms a hard,
tight, insoluble, microscopic crystalline
structure within the treated material creating
an impermeable water barrier. The unique
crystalline structure actually fuses into the
material, encapsulating surface and interior
particles while filling up capillaries and macro
and micro spaces within the material. Once the
protective water sealer is fully dried the
effect is irreversible and the water resistance
of the treated material is permanent. If
combines the latest advances in the water sealer
technology with tried and proven silicate
technology creating a protective water sealer
that is unmatched and unsurpassed at
withstanding the elements. It is a
“one-of-a-kind” protective water sealer and is
the result of years of research based upon
advanced reactive siliconate technology. It is
in a class by itself and differs greatly from
other water repellents and water sealers on the
market. Zerovoc was developed for any
application where long-term durability and
extreme water protection are required.
|
