Abstract:
A recording medium is provided which includes a microporous thermoplastics film having a fibrillar or reticulated structure and a contrasting underlayer. Impact on the microporous film causes it to change from an opaque to a clear state revealing the contrasting underlayer. The medium may be used to reveal impact e.g. of a golf ball on the head of a golf club to which it is attached, it may be printed in an impact or thermal printer or it may be used to detect temperature rises above a characteristic limit at which the film becomes transparent.
Abstract:
A gel wound dressing which comprises a water absorbent copolymer of a starch and a monounsaturated carboxylic acid or an ester or salt thereof, and water. Preferably, the particles of the copolymer are small, such that at least about 70 % of the particles have a particle size of not more than about 100 mu m.
Abstract:
A filter comprises a filter tube of a porous polymeric material, which is set so that it has a tendency to collapse towards a pre-determined flattened configuration, and a porous support sleeve disposed around the filter tube to support it against internal fluid pressure while providing no more resistance to flow of fluid than the filter tube. The support sleeve can also be set so that it has a tendency to collapse towards a flattened configuration.
Abstract:
Crown ether compounds which can function as receptor molecules for species such as alcohols, especially for ethanol, and other materials capable of forming hydrogen bonds. The compounds are based on 1,7-diaza-12-crown-4 group, substituted on the diaza groups with alkaryl groups as in formula (I) or with bridges extending to diaza groups on another 1,7-diaza-12-crown-4 group as in formula (II).
Abstract:
A composite polymer membrane comprises a first polymeric material which defines a porous matrix, and a second polymeric material which at least partially fills, and thereby blocks, the pores of the matrix, each of the first and second materials, being crosslinked. The membrane preferably includes a layer of an ethylenically unsaturated carboxylic acid which is graft-polymerised with the first polymeric material of the porous matrix on a surface thereof. Crosslinking the matrix has been found to improve the transport characteristics of species through the membrane, such as the barrier performance of the membrane towards species dissolved in solution.
Abstract:
A microporous polymeric film comprises a halopolymer in which the repeating units are -(CnH2n)- and -(CmX2m)- in which each X independently represents fluorine or chlorine and the values of n and m are greater than one and less than six. The film is the result of firstly melt processing a mixture of the halopolymer, an extractable salt and extractable polymer secondly extracting at least some of the extractable salt to render the film porous and extracting at least some of said polymer to impart surface porosity to the film. The film may be used as the separator of an electrochemical cell e.g. a battery having a lithium anode and a thionyl chloride electrolyte. High porosities and good electrical properties can be obtained by using as extractable polymer a material having a molecular weight less than one million e.g. a polyethylene oxide of molecular weight about 100,000 - 300,000. The film may be made in relatively long lengths by addition of an anti-oxidant to the mixture to be melt processed.
Abstract:
A polymeric sheet, which is particularly suited for use as a separator in an electrochemical device, is formed, by graft copolymerising acrylic acid, or another vinyl monomer capable of reacting with an acid or a base to form a salt directly or indirectly, with fibres of a non-woven sheet, whose outer surface is provided by a polyolefin, especially polypropylene. The polyolefin is crosslinked as a result of the polymerisation reaction. The polymerisation reaction is preferably initiated by exposure of the sheet to ultraviolet radiation, after impregnation with an appropriate solution of the vinyl monomer.
Abstract:
A liquid crystal material is incorporated into a porous polymer matrix having generally random pores of internal volume 10-100 cubic microns to provide an article that may be used in e.g. electro-optical devices, for example windows for buildings, whose transmissivity may be adjusted by variation of an applied electric field.
Abstract:
A microporous polymeric film of high porosity comprises a halopolymer in which the repeating units are -(CnH2n)- and -(CmX2m)- in which each X independently represents fluorine or chlorine and the values of n and m are greater than one and less than six. The film is the result of firstly melt processing a mixture of the halopolymer, more than 150 parts by weight of an extractable salt and not more than 80 parts by weight of an extractable polymer per 100 parts by weight of the halopolymer, the extractable polymer not being completely and homogeneously mixed with the halopolymer and being less viscous than the halopolymer when both are molten so that the surfaces of the film resulting from melt processing are rich in the extractible polymer, and secondly extracting at least some of the extractable salt to render the film porous and extracting at least some of said polymer to impart surface porosity to the film. The film has a porosity of more than 50 % by volume and more usually 60-70 %. The film may be used as the separator of an electrochemical cell e.g. a battery having a lithium anode and a thionyl chloride electrolyte. It has further been found that high porosities and good electrical properties can be obtained by using as extractable polymer a material having a molecular weight less than one million e.g. a polyethylene oxide of molecular weight about 100,000.