synopsisThe effects of gas plasma generated by electrodeless (inductive coupling) glow discharge on polymers were investigated as functions of gas pressure, discharge power, exposure time, and type of plasma gas. A remarkable similarity between the plasma susceptibilities of low molecular weight organic compounds and polymers was observed ; i.e., polymers which have ether, carbonyl, ester, or carboxylic acid attached to a nonaromatic structure are very susceptible to plasma. The weight loss was proportional to the exposure time and exposed area. The discharge power and type of gas were found to have a great influence on both the rate of weight loss and the morphology of the exposed surface. The predominant effect of plasma on polymers was found to be degradation (manifested by weight loss). The crosslinking effect was found to be marginal with many polymers; however, significant crosslinking was observed with double bond-containing polymers. The crosslinking was examined by swelling the treated films. With copolymers of styrene-butadiene, 4-vinylpyridine-butadiene, methacrylic acidbutadiene, and acrylic acid-butadiene, the crosslinking was greatly dependent on the discharge power, the butadiene content of the copolymers, and the exposure time. Both degradation and crosslinking by gas plasma were generally limited to the exposed surface; however, the propagation of crosslinking in the direction of thickness was observed with copolymers of styrene-butadiene. The plasma of organic vapor also causes degradation of plasma-susceptible polymers, particularly at high wattage, although the deposition of polymer occurs simultaneously.

Extremely thin polypropylene films formed by evaporation of dilute solutions floating on water, thin films deposited on Mylar or on carbon‐coated Mylar, and bulk samples were deformed; after etching with aqua regia or chromic acid, the surfaces were studied by electron microscopy of surface replicas. At small draw ratio, microfibrils with lateral dimensions of about 200 Å, originating in micronecks at crack boundaries of the original crystal lamellae, were obtained in isolated areas exhibiting maximum local strain separated by large regions of much less deformed material. With increasing draw ratio the necked regions grow, the old structure gradually being reduced to smaller and smaller islands until it disappears completely. The inhomogeneity of strain in adjacent bundles of microfibrils creates a great many longitudinal voids with more or less disoriented microfibrils bridging the gaps. The regular arrangement of crystalline blocks of rather uniform length and width can be occasionally seen on surface replicas of drawn samples, and much better on dark‐field electron micrographs of drawn and annealed thin membranes. In the latter case the blocks are very uniform and have similar dimensions along and perpendicular to the axis of the microfibril. The evidence from the electron micrographs, together with previous small‐angle x‐ray scattering data, supports Peterlin's molecular model for plastic deformation of crystalline polymers.

SynopsisBy means of electron microscopy of surface replicas and both small-angle and wideangle x-ray scattering, nylon 6 fibers were investigated in the as-spun state, after drawing at 180°C to a draw ratio up to 4.95, and after subsequent annealing. As spun, the fiber exhibits a small fraction of row-nucleated cylindrites and a great many spherulites (with an average diameter of a few microns) side by side. Drawing deforms the spherulites into spindle-shaped structures (k = 2) and subsequently produces well-aligned microfibrils. Small-angle x-ray scattering yields a two-point diagram at small k and a fourpoint diagram a t high A. The long period seems to decrease slightly with draw ratio. Annealing at temperatures above the temperature of drawing increases the long period to a greater extent with samples of lower k. The crystal lattice orientation is nearly complete a t k = 4.95.

Articles you may be interested in Adsorption geometry and overlayer morphology in the formation of interfaces between metals and (110) III-V surfacesDuring the first stage of plastic deformation before the neck formation the crystal lamellae are rotated into the position of maximum compliance to applied stress that causes the stress--strain curve to drop to the plateau characteristic for deformation with neck propagation. The plastic-flow pattern in the neck results in an asymmetry of strain momentum imposed on tie molecules which during annealing lets the lamellae on the sample surface rotate about an axis parallel to the surface and perpendicular to the draw direction. The temperature at which such a rotation starts increases with the draw ratio. Concurrently the c axis moves away from the draw direction. The rotation of lamellae in the surface layer is nearly prevented by keeping the sample at constant length during annealing and in the interior of the sample by the surrounding lamellae even if the sample is free to shrink. The difference in long period which depends on the temperature of drawing in bulk samples and on the thickness of original crystals in extremely thin films is most probably a consequence of different geometry of heat dissipation in both cases.

Im Gegensatz zu makroskopischen Proben, jedoch in Ubereinstimmung mit den Einkristallen stimmt die Langperiode des plastisch verformten, extrem diinnen Films mit der der rlusgangsprobe iiberein. Beim Tempern wachst die Langperiode und nimmt einheitlichere Werte an. Die Kristallorientierung wird verbessert. Es tritt jedoch keine Rotation der Laniellen um eine in der Ober5ache senkrecht zur Dehnungsrichtung gelegene Achse auf, wie sie bei makroskopischen Proben beobachtet wird.

synopsisOf the 30 monomers and monomer combinations investigated, 11 were polymerized into essentially all powder, 17 into predominantly a film, and two could not be polymerized in an electrodeless rf plasma-initiated gas phase polymerization. Efficient powder formation was mainly determined by the type of the monomer, the monomer partial pressure, the type of inert gas used, and the design of the polymerization chamber. The powders examined consisted of spherical particles of submicron size and were almost completely or partially soluble; and in the case of polystyrene, the powders possesses a very narrow particle-size distribution. In all cases, the soluble material was of a very low molecular weight. The best conversion to powder achieved was 18%.

synopsisCrystallite sizes have been obtained from the breadth of equatorial x-ray reflections from polypropylene samples subjected to a draw ratio of 6 a t 21'C and then annealed a t 155OC, 14OoC, and 12OoC, respectively. For all samples it was found that the ratio of the dimension of the crystallite perpendicular to the { 110) planes to that perpendicular to the (040) plane is a constant. The ratio of the lateral crystallite size to the meridional long period was also found to be constant, independent of annealing temperature. In contrast, the thickness of the crystallites in the direction parallel to the draw direction, as calculated from the meridonal long period and density data, was not proportional to the lateral crystallite size.

The deformation of single crystals shows two preferential directions for crack formation at 60' t o each other. The cracks open very little on crystals lying directly on the Mylar substrate and substantially more on the higher layers of a multilayer crystal. The primary crack direction is parallel to the plane of hydrogen bridges. The microfibrils bridging the cracks are too short for a good dark field electron micrograph. Deformed thin membranes occasionally show a lamellar structure. After annealing at 215OC well oriented single crystal blocks belonging to microfibrils can be observed. Z U S A M M E N F A S S U N G :Die bei der Deformation von Einkristall-Lamellen auftretenden Risse zeigen zwei bevorzugte, unter 60 zueinander stehende Richtungen. Die Risse sind eng bei Kristallen, die unmittelbar auf der Mylar-Unterlage liegen, und wesentlich breiter in den oberen Schicbten von Lamellenpaketen. Die primare Richtung der Risse lauft parallel zu der Ebene der Wasserstoffbriickenbindungen. Die Mikrofibrillen, die die Risse iiberbriicken, sind zu kurz, um brauchbare Dunkelfeldaufnahmen erhalten zu konnen. Deformierte diinne Filme zeigen gelegentlich eine Lamellar-Struktur. Nach dem Tempern bei 215 "C werden gut orientierte Einkristallblocke, die zu den Mikrofibrillen gehoren, beobachtet. * ) Present address : Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo, Japan.