Abstract:
Chromium catalysts may be prepared using a process including contacting a chromium catalyst precursor with a treatment agent. This catalyst may be used for polymerization of a variety of monomers, particularly olefins, to form polymers for a wide variety of applications. The catalyst exhibits desirable activity rates and polymers produced therewith may exhibit improved melt flow, polydisperity values, and changes in shear thinning as compared to those prepared under similar conditions but using the same treatment agent as a cocatalyst instead.
Abstract:
A putter-type golf club head is provided having enhanced moment of inertia and alignment characteristics. The putter head includes a front body and a weight body. The weight body includes a central weight section extending rearwardly from the front body a prescribed distance to a rear weight section. The putter head is configured such that the rear weight section has a width less than the width of the front body and greater than a width of the central weight section. Thus, both the longitudinal and lateral moments of inertia are improved to offer greater forgiveness and increased accuracy during putts. The central weight section may include at least one and more preferably two elongated, high-density elements that are visible on a top surface of the sole between the front body and the rear weight section. The visibility of the elongated elements, with optional parallel markings on a top surface of the golf club head, also act as alignment aids to the golfer.
Abstract:
In the front end of a CDMA cellular or broadband PCS mobile phone receiver, a switched bypass connection is provided to bypass the low noise amplifier, sending the received signal through an amplifier bypass connection. The amplifier bypass connection may include an attenuator. The switched bypass is activated by a control signal generated by a digital signal processor. The digital signal processor analyzes the received signal to detect and determine the relative contribution of the IMD interference to the total received signal power and, when the IMD interference exceeds a predetermined level, sends a control signal to bypass the low noise amplifier. Identification of the presence of IMD interference is by spectral estimation to discern when the mobile phone is in the presence of large near-band signals from an AMPS or other narrow-band base station which causes in-band IMD. In a preferred embodiment, the spectral estimation is performed by collecting a series of data samples from the received signal and, using a digital signal processor (DSP), computing a Discrete Fourier Transform (DFT) to generate frequency domain data, passing the data through a filter bank, then using a decision algorithm to determine whether or not there is sufficient IMD present in the received signal to bypass the LNA. If the IMD level is high enough to warrant bypass of the LNA, the DSP will provide a signal to an automatic gain control (AGC) block for controlling a variable gain amplifier (VGA) to compensate for gain loss due to bypass of the LNA.
Abstract:
A method for forming a high molecular weight liquid crystalline polymer is provided. The method include melt polymerizing two or more precursor monomers (e.g., acetylated or non-acetylated) in the presence of an aromatic amide oligomer. The present inventors have discovered that such an oligomer can lower the melt viscosity of the viscous polymer as it is formed. The ability to lower melt viscosity in situ during melt polymerization enables the formation of high molecular weight polymers that display low melt viscosity and can still be removed from the reactor vessel without solidifying therein. This not only improves the ease of processing, but also allows molecular weights to be reached that are even higher than conventionally practical.
Abstract:
A molded part having a predetermined shape is provided. The molded part may be formed by casting a liquid crystalline polymer composition into a mold cavity at a relatively low shear rate. Due to the use of a relatively low shear rate, the polymer composition does not generally undergo extensive shear orientation, which can allow the resulting part to be further processed using standard finishing techniques. The ability to use relatively low shear rates during casting is achieved in the present invention through the use of an aromatic amide oligomer. More particularly, the present inventors have discovered that the aromatic amide oligomer can serve as a flow aid by altering intermolecular polymer chain interactions, thereby lowering the overall viscosity of the polymer matrix to “ultralow” levels without having a significant impact on the mechanical properties.
Abstract:
A melt-extruded substrate that can be readily thermoformed into a shaped, three-dimensional article is provided. The substrate is formed from a polymer composition that contains a thermotropic liquid crystalline polymer and a unique aromatic amide oligomer. The present inventors have discovered that the oligomer can help increase the “low shear” complex viscosity of the resulting polymer. The ability to achieve enhanced low shear viscosity values can lead to polymer compositions with an increased melt strength, which allows the resulting substrate to better maintain its shape during thermoforming without exhibiting a substantial amount of sag. Due to its relatively high degree of melt strength, the polymer composition is particularly well suited for forming thin extruded substrates for use in thermoforming processes.
Abstract:
A method for forming a high molecular weight thermotropic liquid crystalline polymer is provided. The method includes melt polymerizing two or more monomers in the presence of a unique aromatic amide oligomer to form a prepolymer, and then solid-state polymerizing the prepolymer to achieve a target molecular weight. The present inventors have discovered that a unique aromatic amide oligomer can be employed to help increase the “low shear” complex viscosity of the resulting solid-state polymerized composition. This allows for the attainment of higher than conventional “low shear” complex viscosity values and/or a substantial reduction in the solid-state polymerization time needed to achieve a target complex viscosity. In addition, the oligomeric flow aid can also accelerate the extent to which the “high shear” melt viscosity is increased during solid-state polymerization, which may also contribute to a substantial reduction in the solid-state polymerization time needed to achieve a certain molecular weight.
Abstract:
A method for making a polystyrene ionomer comprises: preparing a metallic comonomer within styrene monomer to form a reaction mixture; and placing the reaction mixture under conditions suitable for the formation of a polymer composition. The metallic comonomer can be a metal acrylate, formed by contacting a metal complex and an acrylate precursor.
Abstract:
A melt-extruded substrate that can be readily thermoformed into a shaped, three-dimensional article is provided. The substrate is formed from a polymer composition that contains a thermotropic liquid crystalline polymer and a unique aromatic amide oligomer. The present inventors have discovered that the oligomer can help increase the “low shear” complex viscosity of the resulting polymer. The ability to achieve enhanced low shear viscosity values can lead to polymer compositions with an increased melt strength, which allows the resulting substrate to better maintain its shape during thermoforming without exhibiting a substantial amount of sag. Due to its relatively high degree of melt strength, the polymer composition is particularly well suited for forming thin extruded substrates for use in thermoforming processes.