Crystallinity and Unit Cell Variations in Linear High-Density Polyethylene

1994 ◽  
Vol 38 ◽  
pp. 495-502
Author(s):  
Kenneth B. Schwartz ◽  
Jinlong Cheng ◽  
Vijay N. Reddy ◽  
Matilda Fone ◽  
Howard P. Fisher
Keyword(s):  
High Density Polyethylene ◽  
Unit Cell ◽  
High Density ◽  
Degree Of Crystallinity ◽  
Lamellar Thickness ◽  
Interfacial Zone ◽  
Unit Cell Parameters ◽  
Scanning Calorimetry ◽  
Cell Parameters ◽  
The Degree Of Crystallinity

Abstract The degree of crystallinity and unit cell parameters have been determined using WAXS on a number of compression molded high-density polyethylene (HDPE) plaques processed at widely varying conditions of crystallization and annealing times and temperatures. Changes in unit cell parameters with variations in processing conditions can be explained in terms of increases in lamellar thickness of polyethylene crystals with increasing thermal treatments. Concomitant increases in the degree of crystallinity of these samples can also be explained in terms of lamellar thickening and other changes in polyethylene morphology. Crystallinity determinations using XRD data are also compared with values determined by differential scanning calorimetry (DSC) and solid-state 13C nuclear magnetic resonance (NMR). Comparisons of crystallinity values obtained by these three different techniques can reveal details of the morphology of HDPE including the presence of an interfacial zone in addition to the crystalline and amorphous components of the system.

scholarly journals Auto-Radiation Damages in Zircons of the Yastrubtsi Ore Occurrence of the Ukrainian Shield According to the Data of NMR and XRD

2021 ◽  
Vol 43 (1) ◽  
pp. 25-33
Author(s):  
A.E. GRECHANOVSKY ◽  
A.M. KALINICHENKO ◽  
E.E. GRECHANOVSKAYA ◽  
A.B. BRIK
Keyword(s):  
Mas Nmr ◽  
Ukrainian Shield ◽  
Degree Of Crystallinity ◽  
Initial Structure ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Radiation Damages ◽  
The Degree Of Crystallinity ◽  
Good Agreement ◽  
Xrd Method

By the method of XRD and high-resolution nuclear magnetic resonance (MAS NMR), the features of the structure of partially metamict zircons from Yastrubtsi ore occurrence of the Ukrainian Shield were studied. Samples 1 and 2 (depths 627 and 1069 m) belong to middle metamict zircons, and sample 3 (depth 1302.5 m) — to weak metamict zircons. The purpose of this work was to elucidate the features of the structure of partially metamictic zircons from Yastrubtsi ore occurrence of the Ukrainian Shield and the features of their recrystallization. The XRD method showed the presence of diffuse diffraction bands, which indicates the presence of an amorphous phase. For sample 3, these bands are less pronounced. After heating at T = 1100°C, these bands significantly decrease. Based on the XRD data, the degree of crystallinity and unit cell parameters of the samples were calculated. To obtain information on the local structure of the samples, spectra were obtained for the initial and annealed samples. It was shown by MAS NMR that there are regions in the initial structure in which [SiO4] tetrahedra are interconnected. These regions are designated Qn (n is the number of bridging oxygen atoms per Si atom). It has been established that the silica phase is practically absent in the zircon samples. In such samples, mainly Q1-2 and Q3 polymerization of silicon atoms occurs (for sample 3, only Q1-2 polymerization is characteristic). The MAS NMR results are in good agreement with the XRD data.

Investigation of thermal and dielectric properties of Fe3O4/high-density polyethylene nanocomposites

2017 ◽  
Vol 51 (28) ◽  
pp. 3923-3929 ◽  
Author(s):  
Fatemeh Ahangaran ◽  
Ali Hassanzadeh ◽  
Sirous Nouri ◽  
Rasoul Esmaeely Neisiany
Keyword(s):  
Dielectric Properties ◽  
Crystalline Structure ◽  
High Density Polyethylene ◽  
Electrochemical Impedance ◽  
High Density ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Polyethylene Matrix ◽  
Average Size

High-density polyethylene nanocomposites containing Fe3O4 nanoparticles were prepared by employing melt mixing process. The amorphous Fe3O4 nanoparticles with average size about 50 nm were prepared by the conventional coprecipitation method from iron (ΙΙ and ΙΙΙ). Thermal and dielectric properties of high-density polyethylene and its nanocomposites were investigated via differential scanning calorimetry and electrochemical impedance spectroscopy. The crystalline structure of high-density polyethylene and Fe3O4/high-density polyethylene nanocomposite were studied by wide-angle X-ray diffraction, which confirmed orthorhombic crystalline structure. The results of thermal and dielectric analysis indicated that the addition of Fe3O4 nanoparticles to high-density polyethylene matrix leads to decreasing degree of crystallinity and improvement of dielectric constant.

Structure and Martensitic Transformation in NiMnSn Alloy Ribbons with Partial Sn Substitution by Al

2013 ◽  
Vol 203-204 ◽  
pp. 232-235 ◽  
Author(s):  
Wojciech Maziarz ◽  
Paweł Czaja ◽  
Marek Faryna ◽  
Tomasz Czeppe ◽  
Anna Góral ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Melt Spinning ◽  
Parent Phase ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Scanning Calorimetry ◽  
Cell Parameters ◽  
Al Content ◽  
Dsc Measurements ◽  
Profile Fitting

The influence of Al substitution for Sn in Ni44Mn43.5AlxSn12.5-x(x= 0, 1, 2, 3) ferromagnetic shape memory alloy ribbons on phase transformation and microstructure evolution is outlined in this paper. Ribbons produced by melt spinning technique showed fully crystalline structure, however non uniform. Energy dispersive spectroscopy microanalysis (EDS) confirmed the average composition of ribbons in accord with the initial alloys. The higher symmetry parent phase was identified with the aid of X-ray diffraction (XRD) as bcc L21Heusler type structure. The unit cell parameters were determined applying the XRD profile fitting method. It was observed that with increase of Al content unit cell parameters and in turn unit cell volume decrease. This may be attributed to the fact that Al has a smaller radius compared to Sn, which it was substituted for. Differential scanning calorimetry (DSC) measurements did not allow to detect the martensitic transformation above -150°C.

Investigating the Limiting Mechanical Properties of Nanocomposites Based on High-Density Polyethylene

2017 ◽  
Vol 44 (12) ◽  
pp. 47-52
Author(s):  
N.S. Dikanova ◽  
A.V. Matseevich ◽  
O.V. Kovriga ◽  
A.A. Askadskii ◽  
T.P. Kravchenko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
High Density Polyethylene ◽  
High Density ◽  
Degree Of Crystallinity ◽  
Elasticity Limit ◽  
Multiwalled Nanotubes ◽  
Twofold Increase ◽  
The Given ◽  
The Degree Of Crystallinity

The effects of nanotubes and modifiers on the elastic modulus and forced elasticity limit of high-density polyethylene were studied. It was found that a very low concentration of multiwalled nanotubes (0.1 wt%) leads to a considerable (twofold) increase in the elastic modulus and a certain increase in the forced elasticity limit. This is connected with the experimentally found increase in the degree of crystallinity of polyethylene when it is filled with the given nanoparticles.

Reinforcing high-density polyethylene by polyacrylonitrile fibers

2018 ◽  
Vol 47 (1) ◽  
pp. 86-94 ◽  
Author(s):  
Lien Zhu ◽  
Di Wu ◽  
Baolong Wang ◽  
Jing Zhao ◽  
Zheng Jin ◽  
...  
Keyword(s):  
Tensile Strength ◽  
High Density Polyethylene ◽  
Flexural Modulus ◽  
High Density ◽  
Degree Of Crystallinity ◽  
Content Type ◽  
Resistance To Deformation ◽  
Different Content ◽  
The Degree Of Crystallinity ◽  
Pan Fibers

Purpose The purpose of this paper is to find a new method to reinforce high-density polyethylene (HDPE) with polyacrylonitrile fibers (PAN). Furthermore, the crystallinity, viscoelasticity and thermal properties of HDPE composites have also been investigated and compared. Design/methodology/approach For effective reinforcing, samples with different content fillers were prepared. HDPE composites were prepared by melt blending with double-screw extruder prior to cutting into particles and the samples for testing were made using an injection molding machine. Findings With the addition of 9 Wt.% PAN fibers, it was found that the tensile strength and flexural modulus got the maximum value in all HDPE composites and increased by 1.2 times than pure HDPE. The shore hardness, storage modulus and vicat softening point of the composites improved continuously with the increase in the proportion of the fibers. The thermal stability and processability of composites did not change rapidly with the addition of PAN fibers. The degree of crystallinity increased with the addition of PAN fibers. In general, the composites achieve the best comprehensive mechanical properties with the fiber content of 9 Wt.%. Practical implications The fibers improve the strength of the polyethylene and enhance its ability to resist deformation. Originality/value The modified HDPE by PAN fibers in this study have high tensile strength and resistance to deformation and can be used as an efficient material in engineering, packaging and automotive applications.

scholarly journals Photocatalytic Degradation of High Density Polyethylene using CaO Nanocatalyst

2020 ◽  
Vol 32 (9) ◽  
pp. 2293-2297
Author(s):  
V.S. KUMAWAT ◽  
J.P. BHATT ◽  
D. SHARMA ◽  
S.C. AMETA ◽  
R. AMETA
Keyword(s):  
Functional Groups ◽  
High Density Polyethylene ◽  
Chain Scission ◽  
High Density ◽  
Degree Of Crystallinity ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry ◽  
Fusion Enthalpy ◽  
Before And After ◽  
Scanning Electron

The photodegradation of high density polyethylene (HDPE) using CaO nanoparticles as a catalyst was carried out using 500 W lamp. After exposure, morphology as well as thermal properties of the HDPE was investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). SEM results showed that the HDPE is more prone to crack into small fragments, which indicated a rise in crystallinity with different amounts of catalyst i.e. CaO nanoparticles. The DSC results confirmed the remarkable influence of photodegradation on degree of crystallinity (XC%), fusion enthalpy (ΔH J g-1) and melting temperature (Tm) of HDPE. Infrared spectrometry (FTIR) demonstrated all functional groups of HDPE, present before and after photodegradation. Overall results showed that HDPE was photodegraded into small fragments successfully by using CaO nanopartilces, where different functional groups such as carbonyl, esters and vinyl were obtained during chain scission.

Differential scanning calorimetry/small-angle X-ray scattering analysis of ultraviolet sensible polypropylene filaments

2021 ◽  
pp. 004051752110533
Author(s):  
Martina Vikova ◽  
Shinichi Sakurai ◽  
Aravin Prince Periyasamy ◽  
Hidekazu Yasunaga ◽  
Miroslava Pechočiaková ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Pigment Concentration ◽  
Degree Of Crystallinity ◽  
Lamellar Thickness ◽  
Drawing Ratio ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
The Degree Of Crystallinity ◽  
Ray Scattering

In this work, ultraviolet (UV) sensible metallocene isotactic polypropylene (miPP) filaments were produced with different drawing ratios and various concentrations of photochromic pigment. The effects of pigment concentration and drawing ratio on the chromatic properties and the structural modification for the miPP filaments were studied extensively by differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS/WAXS) measurements. The change in melting temperature and the polymeric structures, such as lamellar thickness, long period and degree of crystallinity of miPP with the addition of a UV sensible pigment into miPP and the drawing process, were evaluated. The results show that the pigment concentration and the drawing ratio influence the inner structure of miPP filaments. Finally, our investigation shows that SAXS and also WAXS are appropriate to determine the lamellar thickness and the degree of crystallinity established by the DSC approach. This work attempts to correlate the results of lamellar thickness, the degree of crystallinity and the higher-order structure of the polymer acquired by DSC as well as X-ray diffraction (XRD) techniques in order to develop an appropriate approach to find the influence of pigment concentration and drawing ratio on miPP filaments.

scholarly journals Heat capacity and thermal expansion of yttrium tantalate

2019 ◽  
Vol 484 (2) ◽  
pp. 181-183
Author(s):  
A. V. Khoroshilov ◽  
A. A. Ashmarin ◽  
V. N. Guskov ◽  
E. G. Sazonov ◽  
K. S. Gavrichev ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Heat Capacities ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Scanning Calorimetry ◽  
Crystal Lattices ◽  
Cell Parameters ◽  
The Difference

The isobaric heat capacities of two monoclinic (M' and M) modifications of yttrium orthotantalate at temperatures 5–1300 K have been measured by the adiabatic and differential scanning calorimetry methods. It has been demonstrated that the difference in structure between the crystal lattices of M' and M has small effect in the heat capacity, and the difference between the heat capacities of these phases Cp(M)-Cp(M') is small, always positive, and increases in the range of the lowest temperatures. The unit cell parameters of M-YTaO4 have been determined as a function of temperature in the range 300–1173 K.

Preparation and Properties of Recycled PET Fibers Filled Polyethylene Composites

2016 ◽  
Vol 848 ◽  
pp. 89-93 ◽  
Author(s):  
Zhi Gang Wang ◽  
Wen Hao Xi ◽  
Jing Bo Zhou ◽  
Jia Ming Xu ◽  
Guang Li
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Density Polyethylene ◽  
Degree Of Crystallinity ◽  
Environmental Damage ◽  
Scanning Calorimetry ◽  
Recycled Pet ◽  
Recycled Polyethylene ◽  
Pet Fibers ◽  
The Degree Of Crystallinity

Responding to the resource waste and environmental damage, the recycled Polyethylene Terephthalate (PET) fibers were successfully obtained from waste PET textiles using a PFI mill. The high density polyethylene (HDPE)-based composites reinforced with recycled PET fibers were manufactured by melting blend. The mechanical properties of the composites were investigated by mechanical property test. The thermal stability and crystallinity were analyzed by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), and their microstructures were characterized by Scanning Electron Microscopy (SEM). The mechanical properties of the composites indicated the significant improvements in tensile, flexural and impact properties by increasing the recycled PET fibers to 20wt%. The morphological and structural results showed that the recycled PET fibers dispersed well in HDPE matrix with the help of PE-g-MAH as a compatibilizer. The thermal analysis revealed that the degree of crystallinity and crystallizing rate tended to increase, while the thermal stability remained stable. In addition, using PFI mill in dealing with the waste textiles will help open new ways for recycling of waste textiles.

Kinematical and Dynamical CBED Pattern Models: Increasing the Accuracy of the Unit-Cell Parameter Measurements Based on CBED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 540-541
Author(s):  
I.N. Yadhikov ◽  
S.K. Maksimov
Keyword(s):  
Reciprocal Lattice ◽  
Unit Cell ◽  
Reciprocal Lattice Vector ◽  
Unit Cell Parameters ◽  
Lattice Vector ◽  
Cell Parameters ◽  
Accuracy Of Measurements ◽  
The Difference ◽  
Image Position ◽  
Convergent Beam

Convergent beam electron diffraction (CBED) is widely used as a microanalysis tool. By the relative position of HOLZ-lines (Higher Order Laue Zone) in CBED-patterns one can determine the unit cell parameters with a high accuracy up to 0.1%. For this purpose, maps of HOLZ-lines are simulated with the help of a computer so that the best matching of maps with experimental CBED-pattern should be reached. In maps, HOLZ-lines are approximated, as a rule, by straight lines. The actual HOLZ-lines, however, are different from the straights. If we decrease accelerating voltage, the difference is increased and, thus, the accuracy of the unit cell parameters determination by the method becomes lower.To improve the accuracy of measurements it is necessary to give up the HOLZ-lines substitution by the straights. According to the kinematical theory a HOLZ-line is merely a fragment of ellipse arc described by the parametric equationwith arc corresponding to change of β parameter from -90° to +90°, wherevector, h - the distance between Laue zones, g - the value of the reciprocal lattice vector, g‖ - the value of the reciprocal lattice vector projection on zero Laue zone.

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