The present disclosure relates to a method of preparing a polymer including preparing a first polymer mixture by polymerizing while continuously adding a monomer mixture comprising a (meth)acrylate-based monomer, a vinyl aromatic monomer, and a first vinyl cyanide-based monomer to a first reactor; and preparing a second polymer mixture by polymerizing while continuously adding a second vinyl cyanide-based monomer and the first polymer mixture to a second reactor, wherein a starting time of the continuous addition of the second vinyl cyanide-based monomer and the first polymer mixture is a time when a polymerization conversion rate is 40.0 to 55.0%, and a weight ratio of the first vinyl cyanide-based monomer and the second vinyl cyanide-based monomer is 10:90 to 35:65.

The invention relates to a novel synthesis process in order to produce meltable PAN copolymers with increased thermal stability. The PAN copolymers produced using the method according to the invention surprisingly exhibit improved thermal and mechanical properties compared to PAN copolymers produced using methods known from the prior art. The invention additionally relates to corresponding PAN copolymers and to molded bodies produced therefrom or to a method for producing such molded bodies, in particular melt-spun mono- or mufti-filaments.

The invention relates to a novel synthesis process in order to produce meltable PAN copolymers with increased thermal stability. The PAN copolymers produced using the method according to the invention surprisingly exhibit improved thermal and mechanical properties compared to PAN copolymers produced using methods known from the prior art. The invention additionally relates to corresponding PAN copolymers and to molded bodies produced therefrom or to a method for producing such molded bodies, in particular melt-spun mono- or mufti-filaments.

The present invention relates to a method for producing an acrylonitrile-based fiber, the method including: providing a polymer solution including an acrylonitrile-based copolymer containing a carboxylic acid group; mixing 100 parts by weight of the polymer solution with 1 to 6 parts by weight of a hydrophilization solution containing an organic solvent and ammonia water in a weight ratio of 95:5 to 60:40 to prepare a spinning stock solution; and spinning the spinning stock solution. The method controls the viscosity of the spinning stock solution to improve the stretchability and strength of the acrylonitrile-based fiber, and suppresses the occurrence of gelation.

The present invention relates to a method for producing an acrylonitrile-based fiber, the method including: providing a polymer solution including an acrylonitrile-based copolymer containing a carboxylic acid group; mixing 100 parts by weight of the polymer solution with 1 to 6 parts by weight of a hydrophilization solution containing an organic solvent and ammonia water in a weight ratio of 95:5 to 60:40 to prepare a spinning stock solution; and spinning the spinning stock solution. The method controls the viscosity of the spinning stock solution to improve the stretchability and strength of the acrylonitrile-based fiber, and suppresses the occurrence of gelation.

The present disclosure provides a vibrating diaphragm for a miniature sound-producing device and the miniature sound-producing device. The vibrating diaphragm is made of nitrile rubber; the nitrile rubber is prepared by performing cross-linking polymerization on polyacrylonitrile as a polymerization main monomer and a crosslinking monomer which is polybutadiene, and the content of a polyacrylonitrile block of the polymerization main monomer in the nitrile rubber is 10 to 70 wt %. The vibrating diaphragm provided by the present disclosure has more excellent structural stability, anti-polarization capability and low frequency sensitivity. The miniature sound-producing device provided by the present disclosure has more excellent acoustic performance.

The present disclosure provides a vibrating diaphragm for a miniature sound-producing device and the miniature sound-producing device. The vibrating diaphragm is made of nitrile rubber; the nitrile rubber is prepared by performing cross-linking polymerization on polyacrylonitrile as a polymerization main monomer and a crosslinking monomer which is polybutadiene, and the content of a polyacrylonitrile block of the polymerization main monomer in the nitrile rubber is 10 to 70 wt %. The vibrating diaphragm provided by the present disclosure has more excellent structural stability, anti-polarization capability and low frequency sensitivity. The miniature sound-producing device provided by the present disclosure has more excellent acoustic performance.

This invention relates to a hydrophilic polymer and membrane for oil-water separation. More particularly, this invention relates to a super hydrophilic polymer and membrane with zwitterionic property for oil-water separation, and method of producing the same. The hydrophilic polymer comprises polymer repeat units, each unit having at least one negatively charged carboxylic functional group and at least one positively charged amine functional group; and a monomer having a single aromatic ring and an imide functional group.

This invention relates to a hydrophilic polymer and membrane for oil-water separation. More particularly, this invention relates to a super hydrophilic polymer and membrane with zwitterionic property for oil-water separation, and method of producing the same. The hydrophilic polymer comprises polymer repeat units, each unit having at least one negatively charged carboxylic functional group and at least one positively charged amine functional group; and a monomer having a single aromatic ring and an imide functional group.

This invention relates to a hydrophilic polymer and membrane for oil-water separation. More particularly, this invention relates to a super hydrophilic polymer and membrane with zwitterionic property for oil-water separation, and method of producing the same. The hydrophilic polymer comprises polymer repeat units, each unit having at least one negatively charged carboxylic functional group and at least one positively charged amine functional group; and a monomer having a single aromatic ring and an imide functional group.