- published: 03 Nov 2014
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Curing is a term in polymer chemistry and process engineering that refers to the toughening or hardening of a polymer material by cross-linking of polymer chains, brought about by chemical additives, ultraviolet radiation, electron beam or heat. In rubber, the curing process is also called vulcanization.
Despite the wide variety of thermoset resin formulations (epoxy, vinylester, polyester, etc.), their cure behavior is qualitatively identical. The resin viscosity drops initially upon the application of heat, passes through a region of maximum flow and begins to increase as the chemical reactions increase the average length and the degree of cross-linking between the constituent oligomers. This process continues until a continuous 3-dimensional network of oligomer chains is created – this stage is termed gelation. In terms of processability of the resin this marks an important watershed: before gelation the system is relatively mobile, after it the mobility is very limited, the micro-structure of the resin and the composite material is fixed and severe diffusion limitations to further cure are created. Thus in order to achieve vitrification in the resin, it is usually necessary to increase the process temperature after gelation. Cure monitoring methods give a significant insight to the chemical process and define process actions towards achieving specific quality indices of the cured resin systems.
Chemistry is the science of atomic matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds.
Chemistry is sometimes called "the central science" because it connects physics with other natural sciences such as geology and biology. Chemistry is a branch of physical science but distinct from physics.
The etymology of the word chemistry has been much disputed. The genesis of chemistry can be traced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world, particularly the Middle East.
Traditional chemistry starts with the study of elementary particles, atoms, molecules,substances, metals, crystals and other aggregates of matter. in solid, liquid, and gas states, whether in isolation or combination. The interactions, reactions and transformations that are studied in chemistry are usually a result of interaction between atoms, leading to rearrangments in the chemical bonds which hold atoms together. Such behaviors are studied in a chemistry laboratory.
The Cure are an English alternative rock band formed in Crawley, West Sussex in 1976. The band has experienced several line-up changes, with frontman, vocalist, guitarist and principal songwriter Robert Smith being the only constant member. The Cure first began releasing music in the late 1970s with its debut album Three Imaginary Boys (1979); this, along with several early singles, placed the band as part of the post-punk and New Wave movements that had sprung up in the wake of the punk rock revolution in the United Kingdom. During the early 1980s, the band's increasingly dark and tormented music helped form the gothic rock genre.
After the release of Pornography (1982), the band's future was uncertain and Smith was keen to move past the gloomy reputation his band had acquired. With the 1982 single "Let's Go to Bed" Smith began to place a pop sensibility into the band's music (as well as a unique stage look). The Cure's popularity increased as the decade wore on, especially in the United States where the songs "Just Like Heaven", "Lovesong" and "Friday I'm in Love" entered the Billboard Hot 100 chart. By the start of the 1990s, The Cure were one of the most popular alternative rock bands in the world. The band is estimated to have sold 27 million albums as of 2004. The Cure have released thirteen studio albums, 10 EPs and over thirty singles during the course of their career. Since 2010, they have been working on a fourteenth studio album.