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In a fire, PVC can form hydrogen chloride fumes; the chlorine serves to scavenge free radicals, making PVC-coated wires fire retardant. While hydrogen chloride fumes can also pose a health hazard in their own right, it dissolves in moisture and breaks down onto surfaces, particularly in areas where the air is cool enough to breathe, so would ...
When the polymer is heated, the side groups are stripped off from the chain before it is broken into smaller pieces. For example, the PVC eliminates HCl, under 100–120 °C. CH 2 (Cl)CHCH 2 CH(Cl)→CH=CH-CH=CH+2HCl Side group elimination can also proceed in a radical manner.
It is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). Vinyl chloride is a colourless flammable gas that has a sweet odor and is carcinogenic . Vinyl chloride monomer is among the top twenty largest petrochemicals ( petroleum -derived chemicals) in world production. [ 2 ]
General chemical structure of orthophthalates. (R and R' are general placeholders.) Phthalates (US: / ˈ θ æ l eɪ t s / UK: / ˈ (f) θ æ l eɪ t s ˌ ˈ (f) θ æ l ɪ t s / [1] [2]), or phthalate esters, are esters of phthalic acid. They are mainly used as plasticizers, i.e., substances added to plastics to increase their flexibility ...
N-O• + R• → N-O-R Although they are traditionally considered as light stabilizers, they can also stabilize thermal degradation. Even though HALS are extremely effective in polyolefins, polyethylene and polyurethane, they are ineffective in polyvinyl chloride (PVC). It is thought that their ability to form nitroxyl radicals is disrupted.
A premature ventricular contraction (PVC) is a common event where the heartbeat is initiated by Purkinje fibers in the ventricles rather than by the sinoatrial node. PVCs may cause no symptoms or may be perceived as a "skipped beat" or felt as palpitations in the chest.
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Hence, the P-R interval after the PVC is longer than the baseline P-R interval. [ citation needed ] Concealed conduction can be seen in cardiac aberrancy when a bundle branch temporarily blocks due to being refractory, and conduction from the other bundle branch conceals into the blocked branch retrograde thus perpetuation the bundle branch ...