scholarly journals The Influence of Nano CaCO3 on Nucleation and Interface of PP Nano Composite: Matrix Processability and Impact Resistance

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1389
Author(s):  
Meshal Al-Samhan ◽  
Fatema Al-Attar ◽  
Jamal Al-Fadhli ◽  
Mustafa Al-Shamali
Keyword(s):  
Polymer Matrix ◽  
Impact Resistance ◽  
Nucleating Agent ◽  
Composite Matrix ◽  
Nano Composite ◽  
Nucleation Behavior ◽  
High Frequencies ◽  
The Past ◽  
Fine Control ◽  
Twin Screws

Polypropylene (PP) is a commodity material that has been increasingly used in different industries in the past two decades due to its versatile properties when enhanced with additives. Homo polypropylene, in general, has weak mechanical properties and limited chemical resistance; thus, using a different type of fillers to adjust such properties to fit the required applications opened a large market for this commodity. Understanding the interface constituent between the polymer matrix and the added filler and the nucleation behavior is a key to fine control of the enhancement of PP properties. In this study, PP was incorporated with nano calcium carbonate (CaCO3) at 2 and 5 wt% in the presence of maleic anhydride (MAH) to overcome the weak interface due to low polymer polarity. The mix was compounded in a twin screws extruder at a temperature range of 180–200 °C ; then, the prepared samples were left to dry for 24 h at 25 °C. Nuclear Magnetic Resonance (NMR) was used to study the interface adhesion of the nanofiller and the curved revealed that at 2% of nano CaCO3 PP structure remained the same and the nano experienced good adhesion to the polymer matrix. The mechanical impact resistance results showed a real enhancement to the polymer matrix of the nanocomposite by 37%. Moreover, DSC results showed a faster crystallinity rate due to the nanofiller acting as a nucleating agent and rheology tests indicated that low content of nano additive (2%) has better processability behavior, with suitable viscosity complex values at high frequencies.

Synthesis and Characterizations of Poly(Butylene Succinate) Copolyester

2014 ◽  
Vol 1015 ◽  
pp. 381-384
Author(s):  
Li Liu ◽  
Li Hai Cai ◽  
Dan Liu ◽  
Jun Xu ◽  
Bao Hua Guo
Keyword(s):  
Mechanical Properties ◽  
Polymer Matrix ◽  
Crystallization Temperature ◽  
In Situ Polymerization ◽  
Nucleating Agent ◽  
Single Fiber ◽  
Butylene Succinate ◽  
Crystallization Behaviors ◽  
Polymerization Method

The poly (butylene succinate) (PBS) and 3 wt% attapulgite (ATP) reinforced PBS/ATP nanocomposites with 1,6-hexanediol were fabricated using an in situ polymerization method. The crystallization behaviors indicated that ATP had effectively acted as nucleating agent, resulting in the enhancement on the crystallization temperature. The SEM results showed a superior interfacial linkage between ATP and PBS. Also, ATP could disperse as a single fiber and embed in the polymer matrix, which resulted in the improved mechanical properties.

scholarly journals Spectra of Southern Radio Sources

1977 ◽  
Vol 74 ◽  
pp. 85-97 ◽  
Author(s):  
J. G. Bolton
Keyword(s):  
Time Scale ◽  
Galactic Plane ◽  
Complete Sample ◽  
High Frequencies ◽  
The Past ◽  
Average Accuracy ◽  
Sky Survey ◽  
Two Factors ◽  
Optical Identifications ◽  
One Year

Surveys of the sky between declinations +25° and −90° at 2700 MHz (11 cm) have been in progress for the past 10 years. Excluding some regions close to the galactic plane the whole sky south of +25° has been surveyed to a flux density limit of 0.6 Jy at 2700 MHz and within this area surveys to limits of 0.35, 0.25 or 0.1 Jy have been made covering 3.5 sr. Flux densities have been measured at 5000 MHz for all sources stronger than 0.35 Jy at 2700 MHz. The source positions have an average accuracy of 10″ arc in both coordinates and the positions have been examined for optical identifications on Palomar, ESO or SRC sky survey plates, which now cover 95% of the area. The first part of this paper concerns the relationships between the spectral indices α(2700 to 5000 MHz) and the identifications of the 2300 sources with galactic latitudes greater than 10°. It is a statistically significant sample, since the sources stronger than 0.35 Jy cover 3.5 sr. It is also a representative sample, since no selection was made on the basis of spectral index or identification. It cannot however be claimed as a complete sample, for two reasons. A substantial fraction of sources found in radio surveys at high frequencies are variable - variations of up to a factor of three can occur on a time scale of a year - thus the various sections of the survey are complete only for the relevant epoch. Many of their optical counterparts are also variables - variations of up to a factor of 100 can occur on a time scale of one year. It is hoped to make some assessment of the effect of these two factors in the next two years, when second-epoch Parkes surveys will begin and SRC Schmidt plates will overlap the Palomar Sky Survey.

Study on Crystallization and Rheological Behavior of PEN/PET Blends

2013 ◽  
Vol 830 ◽  
pp. 72-75 ◽  
Author(s):  
Cheng Zhi Chuai ◽  
Kai Li
Keyword(s):  
Tensile Strength ◽  
Rheological Property ◽  
Rheological Properties ◽  
Rheological Behavior ◽  
Impact Resistance ◽  
Crystallization Rate ◽  
Nucleating Agent

The crystallization and rheological properties of PET were studied by using capillary remoter and plate remoter in the paper. The results showed that the addition of PEN could improve the rheological property of PEN/PET blends and the addition of PC could improve the toughness of PEN/PET blends. Besides, Nucleating agent could accelerate the crystallization rate and form crystal particles with small dense in order to improve the properties of impact resistance, tensile strength and transparency of products.

scholarly journals Effect of Quinacridone Pigments on Properties and Morphology of Injection Molded Isotactic Polypropylene

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Mateusz Barczewski ◽  
Danuta Matykiewicz ◽  
Bartłomiej Hoffmann
Keyword(s):  
Isotactic Polypropylene ◽  
Morphological Changes ◽  
Hexagonal Phase ◽  
Impact Resistance ◽  
Polymeric Materials ◽  
Hardness Test ◽  
Thermomechanical Properties ◽  
Scanning Calorimetry ◽  
Nucleation Behavior ◽  
Injection Molded

Two quinacridone pigments were added (0.01; 0.05; 0.1; 0.5; 1; 2 wt%) to isotactic polypropylene (iPP), and their influence on mechanical and thermomechanical properties were investigated. Complex mechanical and thermomechanical iPP properties analyses, including static tensile test, Dynstat impact resistance measurement, and hardness test, as well as dynamic mechanic thermal analysis (DMTA), were realized in reference to morphological changes of polymeric materials. In order to understand the differences in modification efficiency and changes in polymorphism of polypropylene matrix caused by incorporation of pigments, differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) experiments were done. Both pigments acted as highly effective nucleating agents that influence morphology and mechanical properties of isotactic polypropylene injection molded samples. Differences between polypropylene samples nucleated by two pigments may be attributed to different heterogeneous nucleation behavior dependent on pigment type. As it was proved by WAXS investigations, the addition of γ-quinacridone (E5B) led to crystallization of polypropylene in hexagonal phase (β-iPP), while for β-quinacridone (ER 02) modified polypropylene no evidence of iPP β-phase was observed.

scholarly journals Symbiont-mediated cytoplasmic incompatibility: what have we learned in 50 years?

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
J Dylan Shropshire ◽  
Brittany Leigh ◽  
Seth R Bordenstein
Keyword(s):  
Sexual Reproduction ◽  
Cytoplasmic Incompatibility ◽  
Life Sciences ◽  
Relative Fitness ◽  
High Frequencies ◽  
The Past

Cytoplasmic incompatibility (CI) is the most common symbiont-induced reproductive manipulation. Specifically, symbiont-induced sperm modifications cause catastrophic mitotic defects in the fertilized embryo and ensuing lethality in crosses between symbiotic males and either aposymbiotic females or females harboring a different symbiont strain. However, if the female carries the same symbiont strain, then embryos develop properly, thereby imparting a relative fitness benefit to symbiont-transmitting mothers. Thus, CI drives maternally-transmitted bacteria to high frequencies in arthropods worldwide. In the past two decades, CI experienced a boom in interest due to its (i) deployment in worldwide efforts to curb mosquito-borne diseases, (ii) causation by bacteriophage genes, cifA and cifB, that modify sexual reproduction, and (iii) important impacts on arthropod speciation. This review serves as a gateway to experimental, conceptual, and quantitative themes of CI and outlines significant gaps in understanding CI’s mechanism that are ripe for investigation from diverse subdisciplines in the life sciences.

Study on variable nucleation efficiency of N,N ′-Dicyclohexyl-2,6-naphthalenedicarboxamide on isotactic polypropylene

2016 ◽  
Vol 29 (12) ◽  
pp. 1667-1679 ◽  
Author(s):  
Yaoqi Shi ◽  
Zhong Xin
Keyword(s):  
Optical Microscopy ◽  
Isotactic Polypropylene ◽  
Nucleating Agent ◽  
Recrystallization Process ◽  
Schematic Diagram ◽  
Microscopy Observation ◽  
Crystallization Peak ◽  
Nucleation Behavior ◽  
Polarized Optical Microscopy ◽  
Whole Process

N, N′-Dicyclohexyl-2,6-naphthalenedicarboxamide (NU100), a commercial β-nucleating agent (NA) for isotactic polypropylene (iPP), is found dissolvable in iPP melt. Various heating temperatures ( Ths) of iPP/NU100 cause different solubilities of NA, resulting in various aggregation morphologies of NU100 in the melt. Moreover, nucleation efficiency of NA NU100 on iPP changes with the Th of iPP/NU100. In this article, the effects of Th on nucleation behaviors of iPP nucleated with different concentrations of NU100 were systematically studied. The results indicated nucleation efficiency of NU100 depended not only on concentration of NA but also on Th of nucleated iPP. With the increase of Th, crystallization peak temperature ( Tcp) of nucleated iPP decreased remarkably. The whole process that Tcp shifted from 126.8°C to 120.8°C was obtained by investigating the nucleation behavior of iPP/0.1 wt% NU100. Polarized optical microscopy observation confirmed lower Tcp, representing the crystallization of iPP nucleated by dissolved–recrystallized NA NU100. Further, diverse aggregation morphologies of NA in iPP melt during crystallization were observed. A schematic diagram was proposed illustrating the morphologies formed during recrystallization process of NU100 melted at different Ths.

scholarly journals Space Charge Characteristics of Polypropylene Modified by Rare Earth Nucleating Agent for β Crystallization

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 42 ◽  
Author(s):  
Jiaming Yang ◽  
Mingze Gao ◽  
Hong Zhao ◽  
Shilin Liu ◽  
Ming Hu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Space Charge ◽  
Impact Resistance ◽  
Nucleating Agent ◽  
Mechanical Analysis ◽  
Mechanical Relaxation ◽  
Charge Accumulation ◽  
Depolarization Current ◽  
High Voltage Direct Current ◽  
Lamellar Crystals

Compared to cross-linked polyethylene, polypropylene has a thermoplastic property and the advantage of recycling. However, the poor impact resistance at low temperature and the corresponding space charge problem restrict the application of polypropylene with the extruded high voltage direct current (HVDC) cable. Sufficient introduction of the β form of the polypropylene crystal can significantly improve impact resistance at low temperatures. Although it has been widely applied in insulation engineering, the effect of β-crystal on the space charge characteristics of polypropylene has rarely been researched until now. In this paper, a rare earth nucleating agent of β-crystal is employed to modify the performance of polypropylene to investigate the effects of nucleating agent content on β-crystalline, mechanical relaxation, trap, and space charge characteristics of polypropylene. The results of differential scanning calorimeter (DSC) and X-ray diffraction (XRD) tests indicate that the relative content of β-crystal in modified polypropylene increases gradually with the increasing concentration of the nucleating agent, approaching 43.5% when the nucleating agent content has been raised to 0.2 wt %, suggesting appreciable efficiency of the nucleating agent utilized in our research. Scanning electron microscopy (SEM) is utilized to characterize the morphology of β-crystal spherulites, which illustrates that the β-spherulites are in bunchy shape, and the lamellar crystals are parallel to each other without an obvious boundary between them. The results of the space charge test demonstrate that the modified polypropylene can substantially suppress space charge accumulation, which is attributed to an increment of β-crystal content by adopting a rare earth nucleating agent. It is indicated from dynamic mechanical analysis (DMA) measurements that the enhancement of β-crystalline in modified polypropylene can distinctly increase and decrease the β and α relaxation losses, respectively, which proves that the defects in β-crystal and amorphous regions are reduced and increased respectively. Thermally stimulated depolarization current tests further confirm that the number of traps caused by defects in the β-form of polypropylene crystal declines definitely, which dominantly accounts for the suppression of space charge accumulation.

scholarly journals Monthly VLBI Monitoring of Selected Gamma-Bright Quasars

1998 ◽  
Vol 164 ◽  
pp. 43-44 ◽  
Author(s):  
S. Britzen ◽  
A. Witzel ◽  
T.P. Krichbaum ◽  
J. Roland ◽  
S.J. Wagner
Keyword(s):  
Structural Changes ◽  
Gamma Ray ◽  
High Time Resolution ◽  
Radio Sources ◽  
High Frequencies ◽  
Geodetic Vlbi ◽  
High Energies ◽  
The Past ◽  
Curved Trajectories ◽  
Moving Jet

AbstractIn the past few years EGRET observations of extragalactic radio sources demonstrated the presence of blazars at high energies and supplied informations about their enormous luminosities. Questions arose whether outbursts at these high frequencies can be linked to structural changes in the radio regime and the need for VLBI monitoring became obvious. In the past two decades geodetic VLBI measurements gathered this kind of data.We analyzed λ =3.6 cm observations with high time-resolution (up to once a month) from the geodetic IRIS campaigns for the γ-ray active quasars PKS 0420-014 and PKS 0528+134. In both sources superluminally moving jet components could be traced over time periods of several years on curved trajectories. Both sources exhibit component ejections preceding the time of an observed gamma-ray flaring.

The Effect Nucleating Agent on Open-Celled Morphology of Polymer in Vibration

2014 ◽  
Vol 670-671 ◽  
pp. 309-312
Author(s):  
Bing Li ◽  
Bao Shan Huang ◽  
Qiao Zhou Nan ◽  
Xue Mei Qin
Keyword(s):  
Polymer Blends ◽  
Polymer Matrix ◽  
Cell Morphology ◽  
Nucleating Agent ◽  
Vibration Field

The purpose of this work is to analysis on cell morphology of polymer blends foam in different nucleating agent and vibration field. The addition of the nucleating agent promote the nucleating and improve the density of foam. The vibration influences the nucleating agent distribution in the polymer matrix. At the same time, the vibration make the walls between cells thinned, the bubble merged.

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