Methods for extrusion of polyolefins (110) that utilize melt temperature to control molecular weight and also reduce gels. Disclosed herein is an example method for controlling polymer chain scission in an extrusion system (100), comprising: melting a polyolefin resin (110) in extruder (102) at a first melt temperature to form a first melt (112); passing the first melt (112) through a screen pack (106); forming the first melt 112) into a first polyolefin product (116, 118); melting additional polyolefin resin (110) of the same grade in the extruder (102) at a second melt temperature to form a second melt (112), wherein the second melt temperature differs from the first melt temperature by 5° C. or more to control chain scission in the extruder (102); passing the second melt (112) through the screen pack (106); and forming the second melt (112) into a second polyolefin product (116, 118).

The invention relates to a polymer composition comprising a polyethylene and a crosslinking agent, wherein the polymer composition contains a total amount of vinyl groups which is B vinyl groups per 1000 carbon atoms, and B.sub.1≤B, wherein B.sub.1 is 0.88, when measured prior to crosslinking according to method ASTM D624898; and wherein the crosslinking agent is present in an amount which Z wt %, based on the total amount (100 wt %) of the polymer composition, and Z≤Z.sub.2, wherein Z.sub.2 is 0.60, an article being e.g. a cable, e.g. a power cable, and processes for producing a polymer composition and an article; useful in different end applications, such as wire and cable (W&C) applications.

The present invention relates to filtration media made from melt-blown fibers having improved barrier properties. The melt-blown fibers in the filtration media of the invention are made of a visbroken metallocene-catalyzed propylene homopolymer composition with specified melting temperature Tm and molecular weight distribution (MWD).

The present invention relates to melt-blown webs having no shots and improved barrier properties, whereby the melt-blown webs are made of a visbroken metallocene-catalyzed propylene homopolymer composition with specified melting temperature T.sub.m, content of 2,1 erythro regiodefects and molecular weight distribution (MWD).

The invention relates to a process for the preparation of a propylene homopolymer or a propylene α-olefin random copolymer comprising the step of a) preparing a propylene homopolymer or a propylene α-olefin random copolymer, wherein the α-olefin is chosen from the group consisting of ethylene, and α-olefins having 4 to 10 carbon atoms, for example 1-butene or 1-hexene by contacting at least the propylene and optionally α-olefin, with a catalyst in a gas-phase reactor at a temperature T1 and a pressure P1, wherein T1 is chosen in the range from 75 to 90° C., for example in the range from 77 to 85° C., for example in the range from 78 to 83° C., wherein P1 is chosen in the range from 22 to 30 bar to prepare a propylene homopolymer (A′) or a propylene α-olefin random copolymer (A′).

The present invention provides a process for producing a polyethylene composition by treating a cross-linkable ethylene copolymer containing monomer units with hydrolysable silane-groups and polar monomer units. The invention further provides a treated cross-linkable polyethylene composition 5 obtained by the process and a silane-crosslinked polyethylene composition obtained by the process. The invention further provides articles comprising the treated cross-linkable polyethylene composition or comprising the silane-crosslinked polyethylene composition.

Methods for processing LLDPE recyclates including, but not limited to, polyethylene and polypropylene and compositions therefrom are provided. LLDPE recyclate can be visbroken to improve processing characteristics and/or devolatilized to remove waste byproducts to produce processed LLDPE recyclates. Processed LLDPE 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 LLDPE recyclate and/or pre-consumer polyolefins.

Process for obtaining polyethylene with an MFI (190° C./2.16 kg) of at least 4 g/10 minutes and a melt strength (190° C.) of at least 8.0 cN, said process involving extrusion of low density polyethylene (LDPE) with an MFI of at least 5 g/10 minutes and a vinyl content of less than 0.25 terminal vinyl groups per 1000 C-atoms (measured with NMR in deuterated tetrachloroethane solution)—in the presence of 500-5,000 ppm, based on the weight of low density polyethylene, of an organic peroxide.

Disclosed herein are ethylene-based polymers generally characterized by a density of at least 0.94 g/cm.sup.3, a high load melt index from 4 to 20 g/10 min, a zero-shear viscosity at 190° C. from 20,000 to 400,000 kPa-sec, and a relaxation time at 190° C. from 225 to 3000 sec. These ethylene polymers can be produced by peroxide-treating a broad molecular weight distribution Ziegler-catalyzed resin, and can be used in large diameter, thick wall pipes and other end-use applications.

Disclosed herein are ethylene-based polymers having low densities and narrow molecular weight distributions, but high melt strengths for blown film processing. Such polymers can be produced by peroxide-treating a metallocene-catalyzed resin.