摘要:
Low level irradiation of narrow molecular weight distribution, linear, low density ethylene/alpha-olefin copolymer sufficient to introduce crosslinks into the copolymer but insufficient to provide for significant gelation produces improved copolymer rheology providing superior film fabrication.
摘要:
Disclosed is a method and apparatus for ensuring uniform distribution of higher and lower viscosity or flow rate resins in a product produced by a coextrusion process. A flow restriction is provided in the flow path of the lower viscosity or flow rate resin to increase the pressure drop of this resin as it passes through a coextrusion die. The increased pressure drop introduced by the flow restriction causes the lower viscosity or flow rate resin to be more uniformly distributed in the extruded product. A specific die construction providing a uniform resin flow channel within the die is also described.
摘要:
Apparatus for moulding articles of synthetic plastics. Plasticized plastics material is fed by a screw within a cylinder, along the cylinder to a nozzle from whence the material is injected into the mould cavity. The feeding of the material into the mould cavity is however effected by rotation of the screw almost in its forwardmost position instead of by longitudinal movement of the screw from its rearwardmost to its forwardmost position. The longitudinal position of the screw is adjusted during filling of the mould cavity by biasing apparatus acting axially on the screw and controlled by means sensing the position of the screw.The temperature distribution throughout the cylinder, the nozzle, the screw and the screw tip is controlled by separate cooling circuits for the various zones, the various cooling circuits coming into operation at various times during a moulding cycle, as determined by timing apparatus.
摘要:
Aramid fiber reinforced hose having the fiber in discrete particles extruded with the elastomer to provide orientation of the aramid fibers in two oppositely helical overlapping directions. A strainer plate is located within the extruder that has a series of apertures on concentric circles with each series of apertures extending through the plate at opposite helical directions.
摘要:
Multilayer film or sheet prepared by coextrusion is extruded wherein the thickness of the inner layers is varied by varying the flow of one component to the central portion of the sheet while diverting that portion to an external portion of the sheet or film.
摘要:
The invention relates to an apparatus for the extrusion of temperature sensitive thermoplastics to form structural rib-free semi-finished products in contra-rotating driven screws.
摘要:
Improved extrusion apparatus is shown for the preparation of a rod-like body from a coal-containing particulate mixture. Control mechanisms are disclosed for automatically controlling the throughput resistance experienced by the rod-like (or a developing version thereof) body through a die. Portions of the die wall near the outlet end thereof are adapted for inward displacement in response to these control mechanisms. This embodiment may also be coupled with a longitudinally movable die and control means for adjusting the length of the consolidating coal-containing mixture in contact with the surface of the movable die.
摘要:
The pressure and temperature and in some cases the flow rate of fluids such as polymers are controlled by reducing the cross-sectional area of the conduit carrying the fluid to provide a flow channel communicating with the inner surface of the conduit whose cross-sectional area is less than that of the conduit. A valve housing is provided containing a chamber which communicates with the flow channel. The pressure and temperature and in some cases the flow rate of the fluid is controlled by adjusting the position of a valve member slideably disposed in the chamber. As the valve member slides within the chamber, it enlarges or reduces the cross-sectional area of the flow channel to change the flow resistance of the channel, thereby changing the pressure and temperature upstream of the channel and in some cases the flow rate through the channel.In applications where the material at the upstream end of the channel is wet and at a substantially greater pressure than the downstream end, it is desirable to also provide an elongated chamber whose inlet port communicates with the downstream end of the channel and which contains means for advancing and compacting material emanating from the downstream end of the channel. In cases where fragmentation of the material is produced by a rapid, and sometimes explosive, vaporization of the moisture associated therewith upon exposure of the material to the low pressure at the downstream end of the channel, the chamber contains the explosion, collects the resulting fragmented materials and compacts the fragments into a form more convenient to handle.
摘要:
A composite article suitable for forming liquid-containing paperboard cartons is made by laminating an extruded thermoplastic film to an elongated paperboard web. The film has thick and thin strips and the thick strips are laminated to the web over areas thereof which are to ultimately form the bottom portions of the cartons. Thermoplastic material is regulated within an extruder and after extrusion the film takes on a profile imparted by the regulation of the material within the extruder die.
摘要:
A process is provided for the production of a cellular thermoplastic body, wherein solid thermoplastic material is melted under pressure in an extruder, a gaseous blowing agent is injected into the molten thermoplastic material under pressure and said molten thermoplastic material and gaseous blowing agent is passed to a zone of reduced pressure to effect the cellular expansion of said thermoplastic material by said gaseous blowing agent, and wherein said gaseous blowing agent is metered at sonic velocity at a point upstream of the injection of said gaseous blowing agent into said molten thermoplastic material.