Abstract: The invention features linear copolymers prepared from mixtures of allenes and alkynes. The new copolymers have the formula: ##STR1## wherein R.sub.1 through R.sub.6 are, independently, H, an alkyl, an aryl, a phenyl or substituted phenyl, an alkoxy, or an aryloxyl, x+n is 1 to 10,000, and m is 1 to 10,000. The invention also features efficient methods of preparing the new copolymers using nickel or palladium catalysts.

Abstract: The invention is to provide elastomer-like or rubber-like, recyclable cross-linked polymers capable of being liquefied and re-molded repeatedly without detracting from the physical properties of the polymers. The polymer comprises meltable cross-linked oligomer units and linkage units via which the oligomer units are linked to construct the main chains of the polymer. Each linkage unit in the polymer comprises a chemical bond that can be cleaved and re-formed repeatedly by predetermined treatment by which the bond between monomers in the oligomer units are not cleaved. The method for producing the polymer comprises a step of forming oligomer units by polymerizing monomers, a step of forming linkage units by linking the oligomer units via linkage units and a step of forming cross-linked units between the oligomer units.

Abstract: A recyclable polymer is formed of a plurality of oligomer units obtained by polymerizing a fixed number of monomers, and linkage units for linking the oligomer units through a chemical bond which is different from a bond between monomers constituting the oligomer units, thereby allowing repetitive scission and re-bonding of the linkage units by a predetermined treatment not cleaving the bond between monomers. The recyclable polymer is decomposable into oligomers and the oligomers can be linked again into the original polymer without degrading the quality of the polymer. A process for producing the recyclable polymer, a method for recovering the recyclable polymer, and a method for regenerating the recyclable polymer are also provided.

Abstract: A printer in which an end surface of a paper cutter having a sharp blade can be utilized as a paper carrying path by shunting the continuous sheet from the blade. The paper cutter is disposed in the carrying path of the continuous sheet. The paper cutter has a blade extending in a direction transverse to a carrying direction of the continuous sheet at its distal end. A conducting protrusion is formed on a part of the blade of the paper cutter along an extending direction of the blade. An outer periphery of the conducting protrusion, which contacts with the continuous sheet, has a cross section of a substantially circular arc.