31 Sentences With "polymethyl methacrylate"

Polymethyl methacrylate (PMMA) is used in the construction, automotive and electronics industries and known by brand names such as Plexiglas.

Eye prosthetics, polymethyl methacrylate Polymethyl methacrylate (PMMA), commonly known as acrylic, is a transparent thermoplastic available for use as ocular prosthesis, replacement intraocular lenses when the original lens has been removed in the treatment of cataracts and has historically been used as hard contact lenses. PMMA has a good degree of compatibility with human tissue, much more so than glass. Although various materials have been used to make nonintegrated implants in the past, polymethyl methacrylate is one of the implants of choice.

Previous solutions to AMD included bulky glasses or surgical implants. But the development this new contact lens, which is made of polymethyl methacrylate, could offer an unobtrusive solution.

Dentures are mainly made from acrylic due to the ease of material manipulation and likeness to intra-oral tissues, i.e. gums. Most dentures made are fabricated from heat-cured acrylic polymethyl methacrylate and rubber-reinforced polymethyl methacrylate. Coloring agents and synthetic fibers are added to obtain the tissue-like shade, and to mimic the small capillaries of the oral mucosa, respectively. However, dentures made from acrylic can be fragile and fracture easily if the patient has trouble adapting neuromuscular control.

It is one of the most developed method in chain-growth polymerization. Currently, most polymers in our daily life are synthesized by free radical polymerization, such as polyethylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, styrene butadiene rubber, nitrile rubber, neoprene, etc.

The most noticeable thing about the KR200 is its distinctive bubble canopy, which gave rise to the term 'bubble car'. The KR200 continued Messerschmitt's side-hinged canopies. These were usually transparent acrylic ("Plexiglas" or "Perspex"), though reproductions are car-safe polymethyl methacrylate.

However in polymethyl methacrylate (PMMA), a compound similar to PMA, degradation occurs instead. It is soluble in dimethyl sulfoxide (DMSO). PMA is water-sensitive and unlike PMMA, is not stable against alkalies. It is used as macroinitiator to initiate the copolymerisation of HEMA and DMAEMA.

Poly(methyl acrylate) (PMA) is a hydrophobic synthetic acrylate polymer. PMA, though softer than polymethyl methacrylate (PMMA), is tough, leathery, and flexible. It has a low glass-transition temperature about 10°C (12.5°C in case of PMA38). High-energy radiation leads to cross linking in PMA.

Implant creation sequence: CT scan to CAD to 3D printed titanium cranial implant Alloplasty is a method for synthetic implants to be inserted into the body to aid physical and mental function. The procedure can be performed to reconstruct defects such as cranial defects. A common synthetic material used in the production of alloplastic grafts for craniotomy is heat-cure polymethyl methacrylate resin due to being nonconductive, radiolucent, light in weight and is easily modified to smoothly mould to the shape of the skull. The non-conduciveness and biocompatibility of polymethyl methacrylate resin and alloplastic materials in general, provides the ability for alloplastic implants to be used in aiding brain defects that may have been caused by decompressive craniectomy.

Bone cement chemically is nothing more than Plexiglas (i.e. polymethyl methacrylate or PMMA). PMMA was used clinically for the first time in the 1940s in plastic surgery to close gaps in the skull. Comprehensive clinical tests of the compatibility of bone cements with the body were conducted before their use in surgery.

The first acrylic acid was created in 1843. Methacrylic acid, derived from acrylic acid, was formulated in 1865. The reaction between methacrylic acid and methanol results in the ester methyl methacrylate. Polymethyl methacrylate was discovered in the early 1930s by British chemists Rowland Hill and John Crawford at Imperial Chemical Industries (ICI) in the United Kingdom.

Otto Röhm was the first chemist who isolated and applied enzymes in technical applications. This led to a revolution in the production and in the use of washing detergents around 1914. In 1920 he introduced enzymes in the pharmaceutical industry and 1934 in the food industry, first application here was the clarifying of fruit juices. Additionally, the development of polymethyl methacrylate (PMMA) contributed to his economical success.

Polymethyl methacrylate is the cement used with cemented implants, whereas 250-micrometres (diameter) titanium beads usually cover the stem surface of the press-fit implants. The THR is expected to last 10–15 years, which usually surpasses the remaining lifetime of the dog. In less than 5% of cases, the THR will malfunction through loosening of the acetabular cup or femoral fracture. These failures require correction with revision surgery.

Mechanical force can provide a source of energy used by a desired chemical reaction. To create such materials, mechanically sensitive chemical groups called mechanophores are built into the chemical structure of the polymer. In one set of experiments, researchers used spiropyran molecules to detect mechanical stress. The spiropyran (SP) mechanophore was covalently bonded into a stretchy barbell-shaped polymer called polymethyl acrylate (PMA) and a small, glasslike bead-shaped polymer called polymethyl methacrylate (PMMA).

Glass lenses were never comfortable enough to gain widespread popularity. The first lenses to do so were those made from polymethyl methacrylate (PMMA or Perspex/Plexiglas), now commonly referred to as "hard" lenses. Their main disadvantage is they do not allow oxygen to pass through to the cornea, which can cause a number of adverse, and often serious, clinical events. Starting in the late 1970s, improved rigid materials which were oxygen-permeable were developed.

In 2004 there were about 150 MRI units and about 350 CAT units in use in Canada.Press Release CIHI, "CIHI report shows increase in MRI and CT scanners, up more than 75% in the last decade." Medical Imaging in Canada, 2004 The corneal contact lenses first developed in 1949 gained mass appeal in Canada and elsewhere in the 1960s. Made of polymethyl methacrylate (PMMA) they could be worn up to 16 hours a day.

Dip coating have been utilized for example in the fabrication of bioceramic nanoparticles, biosensors, implants and hybrid coatings. For example, dip coating has been used to establish a simple yet fast nonthermal coating method to immobilize hydroxyapatite and TiO2 nanoparticles on polymethyl methacrylate. In another study, porous cellulose nanocrystals and poly(vinyl alcohol) CNC/PVA nanocomposite films with a thickness of 25−70 nm were deposited on glass substrates using dip coating.

A scleral lens is a prototypical lens dating back to the early 1880s. Originally these lenses were designed by using a substance to take a mold of the eye. Lenses would then be shaped to conform to the mould, initially using blown glass and then ground glass in the 1920s and polymethyl methacrylate in the 1940s. Early sclerals were not oxygen permeable, which severely restricted the amount of oxygen provided to the cornea of the wearer.

A 3D "Electrical Tree" (or Lichtenberg figure), imbedded within a 1.5-inch cube of polymethyl methacrylate (PMMA) In electrical engineering, treeing is an electrical pre-breakdown phenomenon in solid insulation. It is a damaging process due to partial discharges and progresses through the stressed dielectric insulation, in a path resembling the branches of a tree. Treeing of solid high-voltage cable insulation is a common breakdown mechanism and source of electrical faults in underground power cables.

Many plastics are completely amorphous, such as: all thermosets; polystyrene and its copolymers; and polymethyl methacrylate. However, some plastics are partially crystalline and partially amorphous in molecular structure, giving them both a melting point, the temperature at which the attractive intermolecular forces are overcome, and also one or more glass transitions, the temperatures above which the extent of localized molecular flexibility is substantially increased. These so-called semi-crystalline plastics include: polyethylene, polypropylene, polyvinyl chloride, polyamides (nylons), polyesters and some polyurethanes.

The principal application, consuming approximately 75% of the MMA, is the manufacture of polymethyl methacrylate acrylic plastics (PMMA). Methyl methacrylate is also used for the production of the co-polymer methyl methacrylate-butadiene-styrene (MBS), used as a modifier for PVC. Another application is as cement used in total hip replacements as well as total knee replacements. Used as the "grout" by orthopedic surgeons to make the bone inserts fix into bone, it greatly reduces post-operative pain from the insertions but has a finite lifespan.

But the center shifted again, this time to Germany because of their superior glass blowing techniques. Shortly following the introduction of the art of glass eye-making to the United States, German goods became unavailable because of World War II. As a result, the US instead made artificial eyes from acrylic plastic. Production of modern ocular prosthetics has expanded from simply using glass into many different types of materials. In the United States, most custom ocular prostheses are fabricated using PMMA (polymethyl methacrylate), or acrylic.

SCF in V-groove (left) V-groove open microfluidic channel (right) Rectangular open-surface U-grooves are the easiest type of open microfluidic channel to fabricate. This design can maintain the same order of magnitude velocity in comparison to V-groove. Channels are made of glass or high clarity glass substitutes such as polymethyl methacrylate (PMMA), polycarbonate (PC), or cyclic olefin copolymer (COP). To eliminate the remaining resistance after etching, channels are given hydrophilic treatment using oxygen plasma or deep reactive-ion etching(DRIE).

After gaining his doctorate, Renfrew worked for DuPont in New Jersey, where he produced a number of patents on polymethyl methacrylate, including one on photopolymerization,M. M. Renfrew (1948) US Patent 2448828 Photopolymerization material for tooth repair,M. M. Renfrew (1943) US Patent 2335133 Tooth Reconstruction as well as epoxy resinsM. M. Renfrew & H. Wittcoff (1955) US Patent 2705223 Thermosetting resinous compositions from epoxy resins and polyamides derived from polymeric fat acids and the first method of synthesis of poly(tetrafluoroethylene) in a form which was suitable for the commercial production of Teflon.

Meanwhile, in the United States, United Technologies Center (Chemical Systems Division) and Beech Aircraft were working on a supersonic target drone, known as Sandpiper. It used MON-25 (mixed 25% NO, 75% N2O4) as the oxidizer and polymethyl methacrylate (PMM) and Mg for the fuel. The drone flew six times in 1968, for more than 300 seconds and to an altitude greater than . The second iteration of the rocket, known as the HAST, had IRFNA-PB/PMM for its propellants and was throttleable over a 10/1 range.

A special tray is an impression tray custom made for an individual patient by a denturist (dental technician), usually made from acrylic, such as polymethyl methacrylate, or shellac. A stock tray is used to make a preliminary impression, from which a model can be cast. This is then used for wax to make the tray to be laid down. The thickness corresponds to specific spacing, and can be classed as spaced, where about 3mm of space is left between the tray and the mucosa for the impression material to occupy, or closely adapted, where less space is left for the impression material.

Dishmaker is a machine which thermoforms cups, bowls, and plates from acrylic (polymethyl methacrylate) plastic discs and then thermoforms them back into discs when they are done being used. It was about the size of a home dishwasher, and could store hundreds of discs for potential dishes. It was designed by Leonardo Bonanni for the Counter Intelligence Group which was active from January 1999 to January 2007 as part of the MIT Media Lab. The Media Lab is an antidisciplinary laboratory, and the Counter Intelligence Group was focused on "developing a digitally connected, self-aware kitchen with knowledge and memory of its activities".

A pair of Intacs after insertion into the cornea A possible surgical alternative to corneal transplant is the insertion of intrastromal corneal ring segments. A small incision is made in the periphery of the cornea and two thin arcs of polymethyl methacrylate are slid between the layers of the stroma on either side of the pupil before the incision is closed by a suture. The segments push out against the curvature of the cornea, flattening the peak of the cone and returning it to a more natural shape. The procedure offers the benefit of being reversible and even potentially exchangeable as it involves no removal of eye tissue.

Plaster is widely used as a support for broken bones; a bandage impregnated with plaster is moistened and then wrapped around the damaged limb, setting into a close-fitting yet easily removed tube, known as an orthopedic cast. Plaster is also used in preparation for radiotherapy when fabricating individualized immobilization shells for patients. Plaster bandages are used to construct an impression of a patient's head and neck, and liquid plaster is used to fill the impression and produce a plaster bust. The transparent material polymethyl methacrylate (Plexiglas, Perspex) is then vacuum formed over this bust to create a clear face mask which will hold the patient's head steady while radiation is being delivered.

Fast neutron detectors differentiate themselves from one another by their 1.) capability of neutron/gamma discrimination (through pulse shape discrimination) and 2.) sensitivity. The capability to distinguish between neutrons and gammas is excellent in noble gas based 4-He detectors due to their low electron density and excellent pulse shape discrimination property. In fact, inorganic scintillators such as zinc sulfide has been shown to exhibit large differences in their decay times for protons and electrons; a feature that has been exploited by combining the inorganic crystal with a neutron converter (such as polymethyl methacrylate) in the Micro-Layered Fast-Neutron Detector . Such detection systems are capable of selectively detecting only fast neutrons in a mixed neutron-gamma radiation field without requiring any additional discrimination techniques such as pulse shape discrimination .

Modern Lichtenberg figures can also be created within solid insulating materials, such as acrylic (polymethyl methacrylate or PMMA) or glass by injecting them with a beam of high speed electrons from a linear electron beam accelerator (or Linac, a type of particle accelerator). Inside the Linac, electrons are focused and accelerated to form a beam of high speed particles. Electrons emerging from the accelerator have energies up to 25 MeV and are moving at an appreciable fraction (95 - 99+ percent) of the speed of light (relativistic velocities). Lichtenberg figure captured in an acrylic block If the electron beam is aimed towards a thick acrylic specimen, the electrons easily penetrate the surface of the acrylic, rapidly decelerating as they collide with molecules inside the plastic, finally coming to rest deep inside the specimen.