摘要:
Esters may be produced with a minimum formation of ether by-product by reacting an organic acid or ester with an alcohol at elevated temperatures in the presence of vinylaromatic polymer beads which are surface functionalized with strongly acidic functional groups, the inner volume of the polymer beads remaining unfunctionalized.
摘要:
This invention relates to the thermal stabilization of halogen-containing polymer compositions, more particularly, this invention relates to a poly(vinyl chloride) (PVC) or a chlorinated polyvinyl chloride (cPVC) composition comprising a methyl tin stabilizer and at least one salt of a polyacid material such as a polycarboxylic acid, a phosphoric acid, or a boric acid.
摘要:
A process for reducing the formation of aqueous phase polymer during the suspension polymerization of unsaturated monomer is disclosed. The reduction of polymer formation in the aqueous phase and subsequent fouling of polymerization reactor surfaces is achieved by incorporating an effective amount of a water-soluble peroxide compound into the aqueous phase used for the suspension polymerization. Hydrogen peroxide, sodium perborate and sodium percarbonate are effective aqueous phase inhibitors for use in the preparation of crosslinked polystyrene beads.
摘要:
Strongly acidic cation-exchange resin beads made by functionalizing jetted, suspension-polymerized, crosslinked, styrenic copolymer beads with sulfonic acid groups produce an unexpectedly high level of conversion when catalyzing condensation reactions, particularly the condensation of phenol with aldehydes or ketones to form bisphenols.
摘要:
A stringed musical instrument is disclosed which includes a body, a first bridge transversely mounted to the body adjacent one end thereof, and a second bridge mounted to the body in the vicinity of the opposite end. First and second string mounting means are positioned longitudinally outward of the first and second bridges, respectively, which tautly suspend a plurality of strings between said bridges. Lever means are provided for raising and lowering at least one of the strings at said first bridge to raise and lower the pitch of the strings.