A method for obtaining low molecular weight polytetrafluoroethylene (PTFE) comprising the following steps: provision of high molecular weight PTFE; arrangement of said high molecular weight PTFE in a chamber, delimited by a gas barrier and containing a controlled atmosphere with an amount of oxygen comprised from 0.005% to 0.5% by volume; hermetically sealing of said chamber containing said high molecular weight PTFE; irradiating said PTFE into said hermetically sealed chamber to obtain said low molecular weight PTFE.

A method for obtaining low molecular weight polytetrafluoroethylene (PTFE) comprising the following steps: provision of high molecular weight PTFE; arrangement of said high molecular weight PTFE in a chamber, delimited by a gas barrier and containing a controlled atmosphere with an amount of oxygen comprised from 0.005% to 0.5% by volume; hermetically sealing of said chamber containing said high molecular weight PTFE; irradiating said PTFE into said hermetically sealed chamber to obtain said low molecular weight PTFE.

A method for producing low-molecular-weight polytetrafluoroethylene containing a reduced amount of C4-C16 perfluorocarboxylic acids and salts thereof, as well as a powder containing low-molecular weight polytetrafluoroethylene, the method including (1) irradiating polytetrafluoroethylene containing a C4-C16 perfluorocarboxylic acid or any salt thereof and having a heat-of-fusion reduction of 40% or lower between first heating and second heating in differential scanning calorimetry with radiation to a dose of 5 to 1000 kGy substantially in the absence of oxygen at a temperature of lower than 100° C. to provide low-molecular-weight polytetrafluoroethylene containing a reduced amount of the perfluorocarboxylic acid and any salt thereof and having a melt viscosity at 380° C. of 1.0×10.sup.2 to 7.0×10.sup.5 Pa.Math.s.

A method for producing low-molecular-weight polytetrafluoroethylene containing a reduced amount of C4-C16 perfluorocarboxylic acids and salts thereof, as well as a powder containing low-molecular weight polytetrafluoroethylene, the method including (1) irradiating polytetrafluoroethylene containing a C4-C16 perfluorocarboxylic acid or any salt thereof and having a heat-of-fusion reduction of 40% or lower between first heating and second heating in differential scanning calorimetry with radiation to a dose of 5 to 1000 kGy substantially in the absence of oxygen at a temperature of lower than 100° C. to provide low-molecular-weight polytetrafluoroethylene containing a reduced amount of the perfluorocarboxylic acid and any salt thereof and having a melt viscosity at 380° C. of 1.0×10.sup.2 to 7.0×10.sup.5 Pa.Math.s.

Methods for processing polyolefin recyclates including, but not limited to, polyethylene and polypropylene and compositions therefrom are provided. polyolefin recyclate feedstocks can be visbroken to improve processing characteristics and/or devolatilized to remove waste byproducts to produce processed polyolefin recyclates. Processed polyolefin recyclates are compounded with pre-consumer polyolefins to produce blend compositions having acceptable or even improved processing characteristics. Such pre-consumer polyolefins can also be visbroken to further tailor processing characteristics of such polymer blends. A combination of extruders and/or extruder zones can be used at the same or different locations for visbreaking and/or compounding of both polyolefin recyclate and/or pre-consumer polyolefins.

A method for producing low molecular weight polytetrafluoroethylene having a melt viscosity at 380° C. of 1.0×10.sup.2 to 7.0×10.sup.5 Pa.Math.s. The method includes: (1) irradiating high molecular weight polytetrafluoroethylene with radiation in the presence of a substance capable of generating a free hydrogen atom and decomposing the high molecular weight polytetrafluoroethylene into a low molecular weight component; and (2) deactivating at least part of main-chain radicals and end radicals generated by the irradiation and providing the low molecular weight polytetrafluoroethylene. Also disclosed is a composition containing the low molecular weight polytetrafluoroethylene and a low molecular weight polytetrafluoroethylene.

A method for producing low molecular weight polytetrafluoroethylene having a melt viscosity at 380° C. of 1.0×10.sup.2 to 7.0×10.sup.5 Pa.Math.s. The method includes: (1) irradiating high molecular weight polytetrafluoroethylene with radiation in the presence of a substance capable of generating a free hydrogen atom and decomposing the high molecular weight polytetrafluoroethylene into a low molecular weight component; and (2) deactivating at least part of main-chain radicals and end radicals generated by the irradiation and providing the low molecular weight polytetrafluoroethylene. Also disclosed is a composition containing the low molecular weight polytetrafluoroethylene and a low molecular weight polytetrafluoroethylene.

The invention relates to a method for manufacturing low-molecular-weight polytetrafluoroethylene, comprising: a) a first step of mixing high-molecular-weight polytetrafluoroethylene with at least one additive selected from the group consisting of ethers having formula R.sup.1—O—R.sup.2, wherein R.sup.1 and R.sup.2 are independently selected among C.sub.1-C.sub.10 straight or branched aliphatic group, C.sub.4-C.sub.10 alicyclic or heterocyclic groups, C.sub.5-C.sub.10 aromatic or heteroaromatic groups; (per)fluorinated vinyl ethers; (per)fluorinated olefins; and optionally substituted aromatic hydrocarbons, and b) a second step of irradiating the so obtained mixture with ionizing radiation, said second step b) being carried out substantially in the absence of oxygen.

The invention relates to a method for manufacturing low-molecular-weight polytetrafluoroethylene, comprising: a) a first step of mixing high-molecular-weight polytetrafluoroethylene with at least one additive selected from the group consisting of ethers having formula R.sup.1—O—R.sup.2, wherein R.sup.1 and R.sup.2 are independently selected among C.sub.1-C.sub.10 straight or branched aliphatic group, C.sub.4-C.sub.10 alicyclic or heterocyclic groups, C.sub.5-C.sub.10 aromatic or heteroaromatic groups; (per)fluorinated vinyl ethers; (per)fluorinated olefins; and optionally substituted aromatic hydrocarbons, and b) a second step of irradiating the so obtained mixture with ionizing radiation, said second step b) being carried out substantially in the absence of oxygen.

Disclosed is a process for preparation of a propylene-based polymer composition involving the steps of: (a) mixing a propylene-based polymer and a peroxydicarbonate in a mixing device, wherein the mixing takes place at a temperature of ≤30° C., wherein the peroxydicarbonate is introduced into the mixing process in a dry form; (b) keeping the mixed composition at a temperature of ≤30° C.; (c) feeding the mixed composition into a melt extruder; (d) homogenizing the mixed composition at a temperature where the propylene-based polymer is in solid state during an average residence time of ≥6.0 and ≤30.0 seconds; (e) further homogenizing the mixed composition at a temperature at which the propylene-based polymer is in the molten state; and (f) extruding the homogenized material from a die outlet of the melt extruder followed by cooling and solidification; wherein the steps (a) through (f) are conducted in that order.