Molecular weight dependency of β phase formation in injection‐molded isotactic polypropylene

2019 ◽  
Vol 137 (15) ◽  
pp. 48555 ◽  
Author(s):  
Xiao Yang ◽  
Cristina Tuinea‐Bobe ◽  
Ben Whiteside ◽  
Phil Coates ◽  
Ying Lu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Phase Formation ◽  
Isotactic Polypropylene ◽  
Β Phase ◽  
Injection Molded

Molecular Weight Induced Conformational Change and Its Impact on β-Phase Formation of Polydiarylfluorene in Dilute Solution

2020 ◽  
Vol 124 (11) ◽  
pp. 6304-6310 ◽  
Author(s):  
Masaru Nagai ◽  
Jie Liu ◽  
Wei Huang ◽  
Moriya Kikuchi ◽  
Seigou Kawaguchi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Conformational Change ◽  
Phase Formation ◽  
Dilute Solution ◽  
Β Phase

scholarly journals The Friction of Structurally Modified Isotactic Polypropylene

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7462
Author(s):  
Natalia Wierzbicka ◽  
Tomasz Sterzyński ◽  
Marek Nowicki
Keyword(s):  
Isotactic Polypropylene ◽  
Heterogeneous Nucleation ◽  
Total Content ◽  
Mold Temperature ◽  
Pimelic Acid ◽  
Reciprocating Motion ◽  
Shore Hardness ◽  
Β Phase ◽  
Forming Temperature ◽  
Injection Molded

The purpose of studies was to analyse an impact of heterogeneous nucleation of modified isotactic polypropylene (iPP) on its tribological properties. The iPP injection molded samples, produced by mold temperature of 20 and 70 °C, were modified with compositions of two nucleating agents (NA’s), DMDBS creating α-form and mixture of pimelic acid with calcium stearate (PACS) forming β–phase of iPP, with a total content 0.2 wt.% of NA’s. A polymorphic character of iPP, with both, monoclinic (α) and pseudo-hexagonal (β) crystalline structures, depending on the NA’s ratio, was verified. The morphology observation, DSC, hardness and tribological measurements as test in reciprocating motion with “pin on flat” method, were realized, followed by microscopic observation (confocal and SEM) of the friction patch track. It was found that Shore hardness rises along with DMBDS content, independent on mold temperature. The friction coefficient (COF) depends on NA’s content and forming temperature—for upper mold temperature (70 °C), its value is higher and more divergently related to NA’s composition, what is not the case by 20 °C mold temperature. The height of friction scratches and the width of patch tracks due to its plastic deformation, as detected by confocal microscopy, are related to heterogeneous nucleation modified structure of iPP.

The Relationship between Structure and Properties of β-Phase Isotactic Polypropylene

2011 ◽  
Vol 233-235 ◽  
pp. 2129-2137 ◽  
Author(s):  
Yuan Hong Shi ◽  
Qiang Dou
Keyword(s):  
Impact Strength ◽  
Isotactic Polypropylene ◽  
Crystal Morphology ◽  
Mechanical Tests ◽  
Strength Increase ◽  
Structure And Properties ◽  
Β Phase ◽  
Injection Molded ◽  
The Relationship ◽  
Melting And Crystallization

In this paper, β-phase isotactic polypropylene (β-iPP) was prepared with two different β nucleating agents (NT-A and NT-D). The melting and crystallization behavior, crystal morphology and mechanical properties of β-iPP were studied by means of DSC, WAXD, PLM and mechanical tests. It is found that the spherulites become smaller, and tensile strength, tensile strain at break and notched impact strength increase for the nucleated iPP. NT-D is more efficient than NT-A. The notched impact strength is three times greater than that of pure iPP for the samples nucleated by NT-D. The injection molded specimens have obvious skin-core structures.

scholarly journals Comparative Study of PVDF Sheets and Their Sensitivity to Mechanical Vibrations: The Role of Dimensions, Molecular Weight, Stretching and Poling

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1637
Author(s):  
Miroslav Mrlík ◽  
Josef Osička ◽  
Martin Cvek ◽  
Markéta Ilčíková ◽  
Peter Srnec ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Comparative Study ◽  
Vinylidene Fluoride ◽  
Initial Thickness ◽  
Complementary Method ◽  
Β Phase ◽  
Vibration Sensing ◽  
Poly Vinylidene Fluoride ◽  
Processing Techniques ◽  
The Comparative Study

This paper is focused on the comparative study of the vibration sensing capabilities of poly(vinylidene fluoride) (PVDF) sheets. The main parameters such as molecular weight, initial sample thickness, stretching and poling were systematically applied, and their impact on sensing behavior was examined. The mechanical properties of prepared sheets were investigated via tensile testing on the samples with various initial thicknesses. The transformation of the α-phase to the electro-active β-phase was analyzed using FTIR after applying stretching and poling procedures as crucial post-processing techniques. As a complementary method, the XRD was applied, and it confirmed the crystallinity data resulting from the FTIR analysis. The highest degree of phase transformation was found in the PVDF sheet with a moderate molecular weight (Mw of 275 kDa) after being subjected to the highest axial elongation (500%); in this case, the β-phase content reached approximately 90%. Finally, the vibration sensing capability was systematically determined, and all the mentioned processing/molecular parameters were taken into consideration. The whole range of the elongations (from 50 to 500%) applied on the PVDF sheets with an Mw of 180 and 275 kDa and an initial thickness of 0.5 mm appeared to be sufficient for vibration sensing purposes, showing a d33 piezoelectric charge coefficient from 7 pC N−1 to 9.9 pC N−1. In terms of the d33, the PVDF sheets were suitable regardless of their Mw only after applying the elongation of 500%. Among all the investigated samples, those with an initial thickness of 1.0 mm did not seem to be suitable for vibration sensing purposes.

scholarly journals Plastic Deformation of Oriented Lamellae. II. Hot Rolling of β-Phase Isotactic Polypropylene

1979 ◽  
Vol 11 (5) ◽  
pp. 383-390 ◽  
Author(s):  
Tsutomu Asano ◽  
Yasuna Fujiwara ◽  
Toshiho Yoshida
Keyword(s):  
Plastic Deformation ◽  
Isotactic Polypropylene ◽  
Hot Rolling ◽  
Β Phase
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