摘要:
It has been discovered that certain compounds serve as particle size regulators when employed together with peroxide initiators for the polymerization of vinylaromatic monomers in the presence of diene polymers. Suitable compounds that can control particle size include, but are not necessarily limited to, cobalt naphthenate, zinc naphthenate, iron octoate, calcium octoate, zinc octoate, zinc neodecanoate, potassium octoate, copper naphthenate, calcium versalate, and the like. Use of these metal carboxylates when vinylaromatic monomers are polymerized in the presence of polybutadienes and peroxide initiators results in reduced polybutadiene particles. Grafting and morphology characteristics may also be improved.
摘要:
A fiber product drawn from an isotactic propylene copolymer of a C2, C4, C5, C6, C7 or C8 &agr;-olefin monomer produced in the presence of a metallocene catalyst characterized by a bridged chiral and stereorigid cyclopentadienyl or substituted cyclopentadienyl ligand structure of a transitional metal selected from group 4b, 5b, or 6b metals of the Periodic Table of Elements, the copolymer having a MFR less than 35, suitably about 30 or less. The copolymer is heated to a molten state and extruded to form a fiber preform. The preform is subjected to spinning at a spinning speed of at least 300 meters per minutes and subsequent drawing at a speed of up to about 1500 meters per minute to provide a draw ratio of at least 1.5 up to 5:1 to produce a continuous fiber having high tenacity of about 3.5 grams per denier and greater and good hand.
摘要:
Blown films and processes of forming the same are described herein. The processes generally include providing a bimodal ethylene based polymer, blending the bimodal ethylene based polymer with at least about 30 ppm peroxide to form modified polyethylene and forming the modified polyethylene into a blown film.
摘要:
Polyethylene modified by using radical initiators such as oxygen and peroxides sometimes has a yellow color which may be reduced or eliminated by incorporating additives such as polyethylene glycol, and/or neutralizing species such as alkali metal stearates, particularly calcium stearate, and zinc oxide.
摘要:
Commonly used triethyl aluminum and tri-isobutyl aluminum cocatalysts can be replaced in olefin polymerizations with a cocatalyst conforming to the formula AlRz(Xz)nLzm wherein Rz is a linear or branched organic moiety having at least 5 carbons and Xz is a linear or branched organic moiety having at least 5 carbons or heteroatom substituted organic moiety or a heterocyclic moiety having at least 4 atoms and can be anionic (n=2) or dianionic (n=1). Xz can also be hydrogen. The aluminum complex may also be in the form of an adduct complex where Lz is a Lewis base and m=1-3. The general formula is subject to the proviso that when n=2, each Xz may be the same or different and that both Xz moieties may not be hydrogen. Use of the invention enables production of a polyolefin film, such as polyethylene film, exhibiting improved bubble stability and other desirable properties.
摘要:
Commonly used triethyl aluminum and tri-isobutyl aluminum cocatalysts may be replaced in olefin polymerizations with a cocatalyst conforming to the formula AlRz(Xz)nLzm wherein Rz is a linear or branched organic moiety having at least 5 carbons and Xz is a linear or branched organic moiety having at least 5 carbons or heteroatom substituted organic moiety or a heterocyclic moiety having at least 4 atoms and may be anionic (n=2) or dianionic (n=1). Xz may also be hydrogen. The general formula is subject to the proviso that when n=2, each Xz may be the same or different and that both Xz moieties may not be hydrogen. The aluminum complex may also be in the form of an adduct complex where Lz is a Lewis base and m=1-3. Use of the invention enables production of a polyolefin pipe, such as polyethylene pipe, exhibiting improved processing, crack resistance and other desirable properties.
摘要:
It has been discovered that improved polystyrene products may be obtained by polymerizing styrene in the presence of at least one multifunctional initiator, at least one chain transfer agent, and at least one cross-linking agent. The presence of the multifunctional initiator tends to cause more branched structures in the polystyrene. A mathematical model that helps optimize the levels of these additives for given molecular weights, melt flow indices (MFIs) and zero shear viscosities (η0) has also been discovered.
摘要:
It has been discovered that the melt instability of styrenic polymers, particularly high impact polystyrene (HIPS) can be reduced or eliminated by the blending therewith of a relatively high melt flow index (MFI) material, such as polystyrene homopolymer. Draw resonance of the melt blend can also be reduced by this method, thereby improving melt processing of these materials. A method to measure melt instability of drawn materials is also discussed.
摘要:
The present invention provides a method for preparing an asphalt and thermoplastic elastomer composition. The process comprises preparing a crosslinking elastomer concentrate that is added to a heated asphalt cut in a stirred tank and then aged to improve SHRP high temperature grading. The crosslinking elastomer concentrate is prepared by adding thermoplastic elastomer and crosslinking agents to a suitable carrier oil, preferably an aromatic oil such as Hydrolene H series. This concentrate is maintained at a temperature that promotes association between the crosslinking agents and the elastomer for a time sufficient for association to substantially complete. In one embodiment, the associating time is in excess of 2 hours up to 24 hours. The asphalt is heated to a temperature sufficient to allow the stirring of the asphalt in the tank. The crosslinking thermoplastic elastomer concentrate is added to the asphalt while continuing to stir the asphalt. The mixture is stirred at a speed and for a period of time sufficient to increase the distribution of the elastomer into the asphalt. Stirring is continued for a period of time sufficient to improve the distribution of the crosslinking thermoplastic elastomer in the asphalt. The composition is then aged as a liquid for 12 to 48 hours to increase the SHRP high temperature grade.