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A quantity of 7,710 Subminiature Metallized Polycarbonate Capacitors of the Second Production Run completed the extended life testing in accordance with Specification MIL-C-39022A, Paragraph 4.7.22.3.2, at +125C temperature at rated voltage for 10,000 hours. These capacitors were life tested in Ovens 1 and 2 up to the required 10,000 hour test period. The remainder of Subminiature Metallized Polycarbonate Capacitors 3,790 continued on test in Oven 3., See Quarterly rept. no. 23, AD-A013 511.

Polycarbonates from bisphenol fluorenone (BPF) have been synthesized by the addition of phosgene to aqueous caustic organic liquid suspensions of BPF and the BPF sodium salt. Addition of BPF end-capped dimethylsiloxane oligomers to these reaction media have resulted in copolycondensations to produce BPF carbonate-dimethyl siloxane multi-sequence black polymers of 7% to 25% dimethylsiloxane with siloxane blocks averaging 10 to 40 units in length. All polymers save one were water white and castable into clear films. Dynamic mechanical measurements, scanning calorimetry and thermooptical analysis are discussed. Mechanical properties are reported. The homopolymer and block polymers have been compression molded. BPF polycarbonate has been extruded as a transparent smooth ribbon at 370C. The ASTM flex strengths of BPF polycarbonate moldings were measured. Flammability and burning behavior are reported.

Ethylene terpolymers varying in molecular weight, hydroxyl content, and degree of partial crosslinking were investigated for the bonding of glass and polycarbonate used in armored windows. The primary requisites for the adhesive were that it be thermoplastic, optically clear, hydrolytically stable, and maintain the integrity of glass-polycarbonate laminate when exposed to either thermal cycling from -65 to + 165 F or ballistic impact. Ethylene terpolymer fulfilled the performance requirements.

Ethylene terpolymer compositions were tested for their use as adhesive for bonding glass- polycarbonate laminates. Ethylene terpolymer provides excellent and controllable adhesion to various glasses and polycarbonate. It is elastomeric and stable over a broad temperature range. It was demonstrated that glass-polycarbonate laminates bonded with the ethylene terpolymer could withstand repeated thermal cycling from -60 to 140 F. The potential for using this in unheated aircraft windshields are indicated. Ballistic tests at velocities up to 1500 feet per second confirm the excellent bond strength of this adhisive to both polycarbonate and glass. (Author, modified-PL)

Strain-time and surface rotation-time data are reported for twenty-seven tests involving axial impact of 0.741 inch diameter polycarbonate rods. An analysis is made of the data to determine various dynamic properties of polycarbonate. The data was obtained using in-surface diffraction grating strain transducers illuminated by a pulsed ruby laser, with the strain and surface rotation-dependent diffraction pattern recorded by high-speed streak cameras. Strain-time histories are obtained for up to 250 micron sec after impact, at locations ranging from one-third to four diameters from impact. (Author, modified-PL)

Disk-shaped specimens of polycarbonate, and polyimide were subjected to flat-plate impact in a light gas gun under well- controlled and well-monitored conditions. For polycarbonate the stress-volume loading and unloading paths were determined under both static and dynamic conditions. Quantitative fractographic analyses on the impacted polycarbonate specimens were carried out and the results were correlated with computed stress histories to obtain analytical relations and graphs enabling one to predict the extent of damage which will be produced in polycarbonate by an arbitrary dynamic load. A similar detailed analysis was not carried out for polyimide because this brittle material fractured in a much more catastrophic manner; for a given stress duration a small stress increment covered the range from incipient shock damage to complete disintegration. However, static stress-volume loading and unloading curves, an approximate constitutive relation, and the shock damage threshold stress for stress durations of about a microsecond were obtained for polyimide. A detailed study of the fracture mechanism was made for both materials. (Author, modified-PL)

The need to provide U.S. Army aircrewmen with increased eye protection saw a production technique developed to make optically acceptable, shatter- and impact-resistant eyeshields from polycarbonate resin. It was found that production quantities of optically transparent polycarbonate lenses can be manufactured with a great deal of reliability by injection-molding processes. Injection-molding of polycarbonate lenses employs standard equipment and techniques. These, however, must be adjusted to account for the idiosyncrasies of the resin, e.g., hygroscopic and flow characteristics. In this fabrication project, the mold used was end-gated and highly polished. Of three available grades of resin, the material with the lowest molecular viscosity provided the best results. The development molds produced about 75,000 acceptable eyeshields which were made available to U.S. Army and Air Force airmen for immediate tactical use. The polycarbonate resin characteristics and molding techniques that influenced the design of the eyeshield, and the development of the fabrication technique are discussed. Also discussed are factors that governed the selection of material type, mold design, and quality assurance considerations.

This experimental study investigates the 'retardation' effects observed when tensile overloads are applied during fatigue tests of polycarbonate, a transparent polymer. Fatigue cracks are grown in 4-point bend polycarbonate specimens at constant stress intensity ranges in order to obtain constant fatigue crack growth rates. Peak overloads are then applied to the specimens in order to investigate their effects on subsequent crack growth. Simple optical methods are used to observe and photograph the crack tip front at the center of the specimen. Tensile overloads are shown to retard fatigue crack growth in polycarbonate in a manner similar to that observed in metals. Crack tip blunting and crack closure appear to be associated with the retardation mechanism; however, their exact relationship is not investigated. It is concluded that polycarbonate offers potential as a model material for further retardation studies. (Author-PL)