Abstract:
A method is provided for making 9,10-dithiaanthracene-2,3,6,7-tetracarboxylic acid dianhydride. Polyimides having improved oxidative stability also are provided which can be made intercondensing organic diamine and the aforementioned dianhydride or a dianhydride mixture.
Abstract:
Branched polyester compositions having high melt viscosities, especially under conditions of low shear, are prepared in a two-step method. The first step is the reaction of a linear polyester, polycarbonate or polyester-polycarbonate containing free carboxylic acid groups with a polyfunctional epoxyalkyl compound such as triglycidyl isocyanurate to form a reactive concentrate. The second step is the reaction of said reactive concentrate with a polyester, such as poly(ethylene terephthalate) or poly(butylene terephthalate), containing a measurable proportion of carboxylic acid end groups. By this two-step method, it is possible to use less epoxy compound for a given melt viscosity level than is the case when the epoxy compound is directly blended with the polyester.
Abstract:
A phase shifting network with multiple outputs between which a constant phase difference is maintained over a large frequency range is disclosed. The configuration consists of a four branch all pass network (10) which in turn consists of four similar all pass networks one in each branch (11, 12, 13, 14). An in phase and an out of phase input signal are applied to this network and four signals in phase quadrature, 0°, 90°, 180°, and 270° may be obtained from the network. The network is designed for operation at frequencies of micro and millimeter wavelengths and may be realized from resistive and capacitive elements fabricated upon a common monolithic substrate. A suitable substrate is gallium arsenide, permitting both passive and active elements to be formed and interconnected by lithographic techniques.
Abstract:
Polyphenylene ether-polyamide compositions having improved resistance to water absorption and swell are provided by incorporating therein a phenolic compound.
Abstract:
Polyphenylene ether-polyamide compositions having improved resistance to water absorption and swell are provided by incorporating therein a phenolic compound.
Abstract:
The stability of polymer mixtures which comprise a polyphenylene ether, a polyamide and an agent to improve the impact strength can be improved by the addition of an ester of a multiple alcohol and a saturated aliphatic carboxylic acid having 5-34 carbon atoms.
Abstract:
A method for producing holes in a polymer film includes the steps of irradiating a spot on the film with a burst of focused laser energy at a level sufficient to damage the film without puncturing it and then subsequently plasma etching the irradiated film so as to remove the damaged portions. This method is particularly applicable to the formation of multichip integrated circuit packages in which a plurality of microcircuit chips are affixed to an underlying substrate which is coated with a polymer film covering the chips and the substrates. The holes are provided for the purpose of interconnecting the chips or making intrachip connections by means of a subsequently applied metallization layer.
Abstract:
Polymer mixtures which comprise an aromatic polycarbonate and a rubber-modified polystyrene. The polystyrene used is characterized by a particular structure: a polystyrene matrix having dispersed therein rubber-like particles with a capsule morphology and an average particle size from 0.2 to 0.6 micrometres.
Abstract:
Room temperature vulcanizable organopolysiloxane compositions based on the use of a silanol or alkoxy terminated organopolysiloxane and an effective amount of a diorganotin dicarboxylate and an amine accelerator.
Abstract:
A transformer comprises a tank (12) containing insulating liquid (14), and within the liquid there is an amorphous-alloy laminated core (20) that comprises spaced-apart upper and lower yokes (21, 22) and two spaced-apart legs (23, 24) at opposite ends of the yokes. Coil structure (17, 18) surrounds the legs, locating the yokes outside the coil structure. Box-like enclosures (40, 42) primarily of electrical insulating material respectively enclose the yokes in positions outside the coil structure. The enclosure (40) about the lower yoke is positioned to capture therein chips of amorphous alloy which might become detached from said core and fall toward the bottom of the tank.