An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A scanning transmission electron microscope has achieved better than 50 pm resolution in annular dark-field imaging mode and magnifications of up to about 10,000,000× whereas most light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000×.
An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and conductors—conduct electric current more easily. The property that distinguishes an insulator is its resistivity; insulators have higher resistivity than semiconductors or conductors. The most common examples are non-metals.
Polyurethane is a commonly encountered polymer composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials (monomers) and is therefore a class of polymers, rather than a distinct compound. This chemical variety allows for polyurethanes with very different physical properties, leading to an equally wide range of different applications including: rigid and flexible foams, varnishes and coatings, adhesives, electrical potting compounds, and fibres such as spandex and PUL. Of these, foams are the largest single application, accounting for 67% of all polyurethane produced in 2016.
A thermoplastic, or thermosoft plastic, is a plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.
Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also collectively called epoxy. The IUPAC name for an epoxide group is an oxirane.
Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device.
Polyvinyl acetate (PVA, PVAc, poly(ethenyl ethanoate)), commonly known as wood glue, white glue, carpenter's glue, school glue, or Elmer's glue in the US, is a widely available adhesive used for porous materials like wood, paper, and cloth. An aliphatic rubbery synthetic polymer with the formula (C4H6O2)n, it belongs to the polyvinyl ester family, with the general formula −[RCOOCHCH2]−. It is a type of thermoplastic.
In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure, or mixing with a catalyst. Heat is not necessarily applied externally, but is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.
Lamination is the technique/process of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance, or other properties from the use of the differing materials, such as plastic. A laminate is a permanently assembled object created using heat, pressure, welding, or adhesives. Various coating machines, machine presses and calendering equipment are used.
Poly(vinyl alcohol) (PVOH, PVA, or PVAl) is a water-soluble synthetic polymer. It has the idealized formula [CH2CH(OH)]n. It is used in papermaking, textile warp sizing, as a thickener and emulsion stabilizer in PVAc adhesive formulations, in a variety of coatings, and 3D printing. It is colourless (white) and odorless. It is commonly supplied as beads or as solutions in water.
A polyol is an organic compound containing multiple hydroxyl groups. The term "polyol" can have slightly different meanings depending on whether it is being used in the field of food science or that of polymer chemistry. Polyols containing two, three and four hydroxyl groups are a diol, triol, tetrol and so on.
A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both.
A polyolefin is a type of polymer with the general formula (CH2CHR)n. They are derived from a handful of simple olefins (alkenes). Dominant in a commercial sense are polyethylene and polypropylene. More specialized polyolefins include polybutene, polyisobutylene and polymethylpentene. Myriad copolymers are known. They are all colorless or white oils or solids. The name polyolefin indicates the dominant olefin from which they are prepared, i.e.,ethylene, propylene, butene, isobutene and 4-methyl-1-pentene. Polyolefins are not olefins, however. Polyolefins are the foundations of many chemical industries.
Hot melt adhesive (HMA), also known as hot glue, is a form of thermoplastic adhesive that is commonly sold as solid cylindrical sticks of various diameters designed to be applied using a hot glue gun. The gun uses a continuous-duty heating element to melt the plastic glue, which the user pushes through the gun either with a mechanical trigger mechanism on the gun, or with direct finger pressure. The glue squeezed out of the heated nozzle is initially hot enough to burn and even blister skin. The glue is sticky when hot, and solidifies in a few seconds to one minute. Hot melt adhesives can also be applied by dipping or spraying, and are popular with hobbyists and crafters both for affixing and as an inexpensive alternative to resin casting.
Pressure-sensitive adhesive is a type of nonreactive adhesive which forms a bond when pressure is applied to bond the adhesive with a surface. No solvent, water, or heat is needed to activate the adhesive. It is used in pressure-sensitive tapes, labels, glue dots, note pads, automobile trim, and a wide variety of other products.
Plastics extrusion is a high-volume manufacturing process in which raw plastic is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weatherstripping, fencing, deck railings, window frames, plastic films and sheeting, thermoplastic coatings, and wire insulation.
4,4′-Oxydianiline is an organic compound with the formula O(C6H4NH2)2. It is an ether derivative of aniline. This colourless solid is a useful monomer and cross-linking agent for polymers, especially the polyimides, such as Kapton.
A release liner is a paper or plastic-based film sheet used to prevent a sticky surface from prematurely adhering. It is coated on one or both sides with a release agent, which provides a release effect against any type of a sticky material such as an adhesive or a mastic. Release liners are available in different colors, with or without printing under the low surface energy coating or on the backside of the liner. Release is separation of the liner from a sticky material; liner is the carrier for the release agent.
A thermoset polymer matrix is a synthetic polymer reinforcement where polymers act as binder or matrix to secure in place incorporated particulates, fibres or other reinforcements. They were first developed for structural applications, such as glass-reinforced plastic radar domes on aircraft and graphite-epoxy payload bay doors on the space shuttle.
Acrylonitrile styrene acrylate (ASA), also called acrylic styrene acrylonitrile, is an amorphous thermoplastic developed as an alternative to acrylonitrile butadiene styrene (ABS), but with improved weather resistance, and is widely used in the automotive industry. It is an acrylate rubber-modified styrene acrylonitrile copolymer. It is used for general prototyping in 3D printing, where its UV resistance and mechanical properties make it an excellent material for use in fused deposition modelling printers.
