To provide a method for producing modified polytetrafluoroethylene, in which formation of a fluorinated oligomer as a by-product is little. A method for producing modified polytetrafluoroethylene which contains substantially no C.sub.6-34 fluorinated oligomer containing hydrophilic functional groups and which contains substantially no fluorinated surfactant, the method comprising conducting copolymerization of tetrafluoroethylene and a monomer having a polar group, in a liquid dispersion 1 comprising a polymer containing units derived from a non-fluorinated monomer and an aqueous medium, or in a solution 2 obtainable by mixing at least one member selected from the group consisting of a polyalkylene oxide compound and a hydrocarbon-containing surfactant, with an oxidizing agent, in an aqueous medium, under such a condition that the amount of the monomer having a polar group to be used, is at most 0.150 mass % to the whole amount of tetrafluoroethylene, to obtain modified polytetrafluoroethylene.

A process for treating a surface coating of a bulk metal part, comprises the steps of placing, in a cavity, at least one what is called metal part including what is called a surface coating that is able to absorb microwaves at the frequency .sub.0, the cavity being surrounded by one or a plurality of first susceptors the dimensions, material and arrangement of which are configured to screen the microwaves at the frequency .sub.0, in the vicinity of each the metal part, and in emitting the microwaves at the frequency .sub.0 into the cavity.

The invention provides a production method for producing low molecular weight polytetrafluoroethylene enabling easy removal of most of C8-C14 perfluorocarboxylic acids and salts thereof, which are unfortunately generated by irradiation, from the low molecular weight polytetrafluoroethylene. The method for producing low molecular weight polytetrafluoroethylene includes: (1) irradiating polytetrafluoroethylene to provide low molecular weight polytetrafluoroethylene having a melt viscosity of 110.sup.2 to 710.sup.5 Pa.Math.s at 380 C.; (2) pulverizing the low molecular weight polytetrafluoroethylene; and (3) heating the low molecular weight polytetrafluoroethylene pulverized in the step (2).

A polytetrafluoroethylene formed product according to an aspect of the invention contains, as a principal component, a polytetrafluoroethylene having a crosslinked structure and has a PV limit of not less than 1600 MPa.Math.m/min.

The present invention provides, among other aspects, stabilized chromophoric nanoparticles. In certain embodiments, the chromophoric nanoparticles provided herein are rationally functionalized with a pre-determined number of functional groups. In certain embodiments, the stable chromophoric nanoparticles provided herein are modified with a low density of functional groups. In yet other embodiments, the chromophoric nanoparticles provided herein are conjugated to one or more molecules. Also provided herein are methods for making rationally functionalized chromophoric nanoparticles.

Low molecular weight polytetrafluoroethylene powder having a complex viscosity of 110.sup.2 to 710.sup.5 Pa.Math.s at 380 C., containing 5 or less carboxyl groups at ends of the molecule chain per 10.sup.6 carbon atoms in the main chain, and being substantially free from C8-C14 perfluorocarboxylic acids and salts thereof. Also disclosed is a method for producing low molecular weight polytetrafluoroethylene.

A non-humidified proton-conductive membrane according to the present invention includes a polymer and a proton-conductive substance. The polymer includes a glassy or crystalline first site having a glass-transition temperature or melting temperature higher than the service temperature of the proton-conductive membrane and a second site capable of forming a noncovalent bond. The proton-conductive substance includes a proton-releasing/binding site capable of noncovalently binding to the second site of the polymer and a proton coordination site capable of coordinating to protons, the proton-releasing/binding site and the proton coordination site being included in different molecules that interact with each other or being included in the same molecule. A proton-conductive mixed phase that includes the second site to which the proton-releasing/binding site of the proton-conductive substance is bound and the proton-conductive substance is lower than the service temperature of the proton-conductive membrane. The amount of the proton-releasing/binding site is excessively large compared with the amount of the second site of the polymer.

The present invention provides, among other aspects, stabilized chromophoric nanoparticles. In certain embodiments, the chromophoric nanoparticles provided herein are rationally functionalized with a pre-determined number of functional groups. In certain embodiments, the stable chromophoric nanoparticles provided herein are modified with a low density of functional groups. In yet other embodiments, the chromophoric nanoparticles provided herein are conjugated to one or more molecules. Also provided herein are methods for making rationally functionalized chromophoric nanoparticles.

To provide a modified PTFE excellent in heat resistance. The modified polytetrafluoroethylene comprises a polymer having units based on tetrafluoroethylene and a polymer having units based on a fluorine-free monomer, wherein the endothermic amount ratio R calculated by a prescribed method is at least 0.65.

To provide a modified polytetrafluoroethylene excellent in breaking strength. The modified polytetrafluoroethylene comprises a polymer having units based on tetrafluoroethylene and a polymer having units based on a monomer represented by formula (1), wherein the content of the units based on a monomer represented by formula (1) is from 10 to 500 mass ppm, to all units in the modified polytetrafluoroethylene, and the standard specific gravity is from 2.155 to 2.175,

CH.sub.2CR.sup.1-L-R.sup.2Formula (1)

wherein R.sup.1 represents a hydrogen atom or an alkyl group, L represents a single bond, COO*, OCO*, or O, * represents a bonding position to R.sup.2, and R.sup.2 represents a hydrogen atom, an alkyl group, or a nitrile group.