Characteristics Of Polypropylene Research Articles

High frequency radar transmittance in bumper and exterior trim parts molded from thermoplastic olefins (TPOs): Part I TPO base resin

AbstractAn extensive investigation of the interaction of thermoplastic olefin (TPO) compounds with high frequency radar wave has been conducted to understand how TPO materials affect radar sensor efficiency, an important function for vehicle safety and especially the advancement of autonomous vehicles. In this article, the effect of major ingredients of a TPO on its dielectric properties was studied, and then a wide range of TPO compounds were evaluated for their radar transmittance or attenuation. It was demonstrated that the characteristics of polypropylene (PP) resin and rubber have little impact on the dielectric properties of a TPO, thus minimal influence on TPO's radar transparency, while increasing the talc loading in the compound increases the dielectric constant of the TPO. The TPO materials containing talc from 7% up to 34% were found to have dielectric constants ranging from 2.30 to 2.70 and nearly zero dielectric loss. Experiments confirmed that parts molded with these materials are transparent to high frequency radar wave at optimized thicknesses. Some pigments for coloring the materials also affect dielectric properties of TPOs, thus radar transmittance, with metal pigments showing the most impact. Finally, commercial TPO products are shown to have great batch to batch consistency in radar transmittance at a selected part thickness.

Influence of injection molding parameters, melt flow rate, and reinforcing material on the weld‐line characteristics of polypropylene

AbstractIn this work, the relation of injection molding parameters to the mechanical properties of various polypropylene grades is investigated to find the optimal processing parameters to minimize weld‐line effects like reduced mechanical and/or optical performance. Injection molded test specimens of five polypropylene grades with different melt flow rates were characterized for their mechanical behavior and compared with equal‐shaped specimens with a colliding weld line in the middle of the specimen. For the production of these weld‐line specimens, a special mold was used and injection molding parameters were systematically varied, tensile (ISO 527‐2) and impact (ISO 179‐1/1eU) properties were measured, and statistical analyses were performed to gain insight on the correlation between melt flow rate and weld‐line behavior. It showed that mechanical properties of specimens with weld lines can be influenced by the processing parameters, but the effect is limited. Positive correlations were found between tool temperature and tensile modulus and strength. Polypropylene grades with low melt flow indexes seem to be more susceptible to weld‐line‐induced property reductions. In a second test series similar to the pure PP investigations, glass‐fiber‐ and talc‐filled PP were used to gain insight into the weld‐line behavior of PP composites. In addition to mechanical characterization, optical and scanning electron micrographs were taken of the weld‐line areas. It was found that the reinforcing particles align along the melt flow front in the weld‐line area. As a result, the mechanical performance of weld‐line specimens is poor. Injection molding parameters were found to have only a small effect.

Preparation and characteristics of polypropylene with long chain branches utilizing the C–H insertion capability of azidoformate

In this study, azidoformate (AF) is investigated as a reactive functional group to mediate noncatalytic C–H insertion reactions to interconnect polypropylene (PP) chains to generate long-chain branches (LCBs). 4,4′-Isopropylidenediphenyl azidoformate (DAF) with two terminal AF groups is synthesized, which is first mixed with propylene/α-olefin copolymer at 100 °C. Then, the prepared mixture with a predetermined amount of DAF is reactively melt mixed with PP at 165 °C. This unique two-step preparation strategy affords PP with prominent rheological properties of LCBs, e.g., shear thinning and strain hardening. The rheological characteristics are easily controlled by adjusting the amount of DAF to afford an effective tool to prepare high-melt-strength PPs. The strength of this strategy is distinct, including a simple/typical melt processing procedure, no degradation of PP chains, and no purification/solvent recycling steps. The C–H insertion capability of azidoformate groups suggests an expandability of this methodology as a platform technology to prepare modified polymers.

Space Charge and Trap Distributions and Charge Dynamic Migration Characteristics in Polypropylene under Strong Electric Field

Space charge accumulation in the polypropylene will accelerate the aging of the material and lead to the degradation of its insulation performance. In the work, space charge distribution, current conduction characteristics, thermally stimulated depolarization current (TSDC) and surface potential decay (SPD) characteristics of polypropylene (PP) under strong electric field are measured and analyzed, and the bulk trap and surface trap parameters are extracted. Further, the charge transport model of PP is established to study the charge dynamic transport physical processes and characteristics under strong electric field. The experimental results show that the charge accumulation amount in PP under the action of negative polarity electric field is higher than that of positive polarity electric field, about one order of magnitude. and the corresponding trap energy levels are 0.84 eV and 0.81 eV, which both belong to deep traps. There are two obvious charge density peaks on the PP surface, which are 2.60 × 1020·eV−1·m−3 and 3.66 × 1020·eV−1·m−3, respectively, and the corresponding surface trap energy levels are 0.86 eV and 0.97 eV. The simulation results show that with the extension of the applied voltage time, the injected charges by the electrode gradually migrate to the bulk of the material and eventually the positive and negative charges are offset at the middle position. The local electric field caused by the accumulation of interfacial charges will weaken the original electric field, while the local electric field caused by the accumulation of the bulk charges will strengthen the original electric field, resulting in the distortion of the internal electric field.

Pengujian Karakteristik Pembakaran Bahan Bakar Minyak Pirolisis Plastik Dan Minyak Jelantah Sebagai Bahan Bakar Alternatif

The purpose of this study was to determine the effect of the ratio of used cooking oil on the combustion characteristics of polypropylene (pp) plastic pyrolysis fuel oil. This study used a mixture of used cooking oil and pyrolysis oil of 75%:25%, 50%:50%, and 25%:75%, respectively. The results of mixing the used cooking oil are burned using a combustion container in an open space with. The maximum temperature obtained from each mixture was 20 minutes for a mixture of 75%: 25% used cooking oil, a 50%:50% mixture, 42 minutes for a mixture of 25%:75%. is 34 minutes.Key Words: Used cooking oil, plastic pyroliysis oil.

Investigation and Optimization of Resistance Implant Welding of Polypropylene Sheets

Recently, the use of resistance welding in the joining of polymeric materials and polymer composites in the aviation, marine, and automotive industries has been gradually increasing. However, challenges continue in regard to improving product quality as affected by several parameters. This study focused on the effects of wire geometries and wire diameters on the characteristics of polypropylene (PP) sheets united by resistance implant welding. Here, PP sheets manufactured by the injection molding method were joined via the resistance upset welding method with three different wire geometries, including spiral, wavy, and M-shaped, and two different wire diameters of 0.3 and 0.5 mm. Mechanical properties, morphological properties, and heating characteristics were examined. The results showed that wire diameter and wire geometry affected amount of heat formation in the weld zone and, therefore, weld performance in terms of the mechanical properties. The results obtained from the study can be used as a reference in similar applications.

Electrical Breakdown Characteristics of Polypropylene for an Eco-Friendly Power Cable

Cross Linked Polyethylene (XLPE) has been widely used as an insulation material of a power cable due to its excellent electrical and mechanical properties. XLPE may cause an environmental devastation because it is not recyclable due to its thermosetting characteristics. Therefore, it is necessary to develop an insulation material which could be replaced with the conventional XLPE owing to its eco-friendly and good dielectric characteristics. In this paper, an analytic study on the comparison between conventional XLPE and six types of eco-friendly polypropylene (PP) samples developed by Hu-innovation Co. Ltd is conducted. As a result, the dielectric characteristics of PP according to manufacturing process are analyzed.

Mehano-chemical synthesis and research hybrid nanocomposite on the basis of polypropylene and clinoptilolite

The separate influence of the coupling agent, aminopropyltriethoxysilane, on the physicomechanical characteristics of polypropylene- and clinoptilolite-based nanocomposites has been considered. It was established that the introduction of the coupling agent improves the properties of nanocomposites. A comparative assessment of the influence of clinoptilolite particle size on the key performance characteristics of polymeric materials is given. The regularities of changes in the properties of composites depending on the concentration of the filler are revealed.

Liquefation Characteristics of Polypropylene by Low-Temperature Pyrolysis by using Co and Mo Dispersed Catalysts under time and loading variations

Liquefation Characteristics of Polypropylene by Low-Temperature Pyrolysis by using Co and Mo Dispersed Catalysts under time and loading variations

Polymerization of propylene in liquid monomer using state-of-the-art high-performance titanium-magnesium catalysts

A comparative study of propylene polymerization in liquid monomer is performed under laboratory conditions using the IK-8-21 Ti-Mg catalyst designed at the Boreskov Institute of Catalysis and imported industrial catalysts (conditionally labeled TMC-1, -2, and -3). The activity and stereospecificity of the catalysts are estimated along with properties of the resulting polypropylene (granular composition and physicomechanical characteristics). It is shown that the IK-8-21 catalyst is not inferior to imported counterparts in terms of catalytic properties in the synthesis of polypropylene. The polypropylene powder formed on IK-8-21 is homogeneous and has good morphology. The physicomechanical characteristics of polypropylene synthesized on the domestic IK-8-21 catalyst are similar to those for polypropylene prepared with the imported TMK-1 catalyst.

Study on the Dynamic Performance of Polypropylene Fiber Reinforced Concrete

The dynamic performance of polypropylene fiber reinforced concrete is studied with the SHPB experiment. The relationship of the strain-stress curves are all obtained in the experiment. The crack characteristics of polypropylene reinforced concrete and plain concrete are also investigated. Analyzed the relation between the character on the crack surface of concrete and material properties and the impact pressure. Also the multi-fractal characteristics are given on the crack surface of concrete. The crack distributions of plain concrete and polypropylene concrete are investigated. The crack resistance effects of polypropylene fiber are analyzed from the degree of closeness and uniformity.

Experimental Study of Rheological Characteristics of Polymer Melts in the Micro-Die

Compared with in the conventional scales, the rheological properties of polymer melts have changed in the micro-scales. Based on the principle of capillary flow and modified with the method of Bagley or zero die micro-die, the rheological characteristics of polypropylene (PP) were investigated using the HAAKE capillary rheometer under the micro-die and conventional die. The results show that: the viscosity of polymer melt modified with the method of bagley or zero die micro-die in the different L/D ratio of micro-die is the same and the shear viscosity of PP decreases with the increase of shear rate; Compared with the viscosity in the conventional scales, the measured viscosity of PP in the micro-scales was reduced by 46% in 0.25mm diameter die, 44% in the 0.20mm diameter die and 88% in the 0.15mm diameter die at the same shear rate; a layer of fixed polymer melt was found in the inwall of the micro-die through the calculation of wall slip rate.

The Plastic Deformation Characteristics of Crystalline Polymer Materials via Rolling Process

The present work investigated the variation of internal structure, molecular orientation, crystallinity and mechanical characteristics of polypropylene(PP) after rolling process. The materials plate became narrow when rolled from entrance to exit, and the internal crystalline gradually deformed and at last destroyed. Plastic deformation was discovered along the rolling direction. In this direction, the crystallinity and vickers hardness were decreased, and molecular orientation was increased. Moreover, molecular orientation had a sharp increase at the second half part of rolling sample. The tensile stress of rolled samples increased by 80% parallel to rolling direction and decreased by 22% perpendicular to rolling direction.

The Effect of Comonomers on the Foaming Characteristics of Polypropylene

In the process of polypropylene (PP) polymerization, different kinds of PP are produced depending on the differences in the structural changes with the arrangement of comonomers. Each kind of PP has distinct properties, which arise from differences in the fundamental chain bonding structure of each polymer and affect not only the mechanical properties but also the foaming characteristics of each resin. Therefore, the fundamental foaming characteristics require experimental investigation. We examined the effects of PP polymerization on the foaming rate and solubility in the microcellular foaming process.

Transobturator approach to suburethral sling placement in the treatment of stress urinary incontinence in women

Minimally invasive suburethral sling procedures have become a mainstay for the surgical treatment of stress urinary incontinence in women. The transvaginal tape sling is the urethral sling most commonly used today. Although the transvaginal tape procedure is safe and efficacious, complications such as bladder, bowel and blood vessel injury have been reported. The most promising recent innovation in minimally invasive surgery for stress urinary incontinence is the transobturator approach for sling placement. This review will cover the mechanism of continence, rationale for the use of suburethral slings in the treatment of stress urinary incontinence, characteristics of polypropylene, comparison of the slings that are commercially available and early data on the efficacy of the transobturator approach in the treatment of stress urinary incontinence.

Effect of surface treatment on polypropylene film-oil interactions

The results are being presented of an investigation to explore the possibility of using surface modification of biaxially oriented polypropylene (BOPP) film in the control of some polymer-oil interactions. The deposition of thin-film polymer structures by means plasma polymerization of styrene in r.f. glow discharges have been used as a method of polymer surface treatment. The change of some characteristics of polypropylene after treatment and effect of use of plasma polymer coating on polymer-oil interaction as well as on resulting dielectric properties of polymer-oil system have been investigated.

Effect of annealing on the mechanical properties and structure of carbon-black polypropylene composites

We present the results of investigation of the behavior of mechanical and various physical characteristics of polypropylene with and without three types of fillers produced in Poland depending on the type of heat treatment. It is shown that if the content of the carbon-black filler is as high as 10%, then the composite behaves as a conductor. Thermal treatment improves all mechanical properties of materials except fracture toughness. This is also partially explained by changes in the crystal lattice.

Comparison of the efficiency of N 2 and NH 3 plasma treatments to improve the adhesion of PP films to in situ deposited Al coatings. Study of ageing phenomena in terms of acid-base properties

This paper reports on the characteristics of polypropylene (PP) treated at two different frequencies, 70 kHz and 13.56 MHz, in two plasma atmospheres, NH 3 and N 2 plasmas. Chemical modifications created on the plasma-treated material were investigated by different complementary surface analytical techniques (X-ray photoelectron spectroscopy (XPS) and contact angle measurements), which revealed a higher reactivity of the NH 3 plasma. The incorporation of nitrogen plays an important role as revealed by the adhesion study of thermally evaporated aluminium with treated PP: the measured peel strengths were two times higher for NH 3-treated surfaces than for N 2-treated ones, with XPS measurements showing a sharper increase of N/C ratio as a function of treatment time for the former treatment. Ageing of the PP pretreated in NH 3 was also studied in terms of surface acid-base properties. The work of adhesion, calculated from contact angle measurements, showed a distinct dependence on the pH value of the test liquids and good correlations were obtained with peel test results. The basic character of the NH 3-treated PP disappears with ageing, leading to an amphoteric surface.

Orientation and Properties of Polypropylene

The orientation characteristics of polypropylene are studied with respect to annealing temperature, orientation temperature, stretch ratio and mode of extension, in order to determine optimum orientation conditions.

Effect of the molecular characteristics of polypropylene on properties of oriented films

The ability of films to fibrillate is determined by nonuniform stresses, which depend on M and MWD. With increase in M and decrease in Mw/Mn, formation of a uniform inter- and intrafibrillar structure takes place, which ensures high physicomechanical properties of the film materials.