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.

Melting, Crystallization Behaviors and Mechanical Properties of iPP Nucleated by β Nucleation Masterbatches

2014 ◽  
Vol 941-944 ◽  
pp. 1229-1232
Author(s):  
Guo Rui Dou ◽  
Qiang Dou
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Impact Strength ◽  
Isotactic Polypropylene ◽  
Tensile Strain ◽  
Mechanical Tests ◽  
Crystalline Form ◽  
Scanning Calorimetry ◽  
Crystallization Behaviors ◽  
Injection Molded

Injection-molded β-isotactic polypropylene (β-iPP) specimens were prepared by adding three β nucleation masterbatches, i.e., NT-MA, NT-MB and NT-MC, respectively. The melting, crystallization and mechanical properties of β-iPP specimens were investigated by means of differential scanning calorimetry (DSC) and mechanical tests. It is revealed that β crystalline form contents were enhanced by the β nucleation masterbatches, and the β contents of the cores were higher than those of the skins of injection molded specimens. The tensile strain at break and Izod notched impact strength of iPP were greatly improved by the β nucleation masterbatches. It was found that the β nucleation efficiency was in the order: NT-MC > NT-MA > NT-MB.

Investigation on β-Polypropylene/Talc Composites

2012 ◽  
Vol 182-183 ◽  
pp. 259-264
Author(s):  
Jia Wei Duan ◽  
Qiang Dou
Keyword(s):  
Polarized Light ◽  
Nucleating Agent ◽  
Mechanical Tests ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Melt Compounding ◽  
Β Phase ◽  
Α Phase ◽  
Melting And Crystallization

In this study polypropylene (PP) composites containing β-nucleating agent (NT-C) and talc filler were prepared by melt compounding. The melting and crystallization behavior, morphology and mechanical properties of the composites were studied by means of differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), polarized light microscopy (PLM) and mechanical tests. The results indicate that talc suppresses the formation of β phase, but promotes the formation of α phase. The Izod notched impact strength and tensile strength of β-PP/talc composites are superior to those of PP/talc composites, indicating an outstanding balance of stiffness and toughness of β-PP/talc composites.

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.

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

Tailored Structure and Properties of Injection-Molded Atactic Polypropylene/Isotactic Polypropylene Blend

2013 ◽  
Vol 1 (8) ◽  
pp. 937-949 ◽  
Author(s):  
Zhengchi Zhang ◽  
Jun Lei ◽  
Yanhui Chen ◽  
Jun Chen ◽  
Xu Ji ◽  
...  
Keyword(s):  
Isotactic Polypropylene ◽  
Structure And Properties ◽  
Atactic Polypropylene ◽  
Injection Molded

scholarly journals Effect of microstructure on the properties of polystyrene microporous foaming material

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 103-110
Author(s):  
Anfu Guo ◽  
Hui Li ◽  
Jie Xu ◽  
Jianfeng Li ◽  
Fangyi Li
Keyword(s):  
Thermal Conductivity ◽  
Compression Modulus ◽  
Cell Diameter ◽  
Compressive Property ◽  
Strength Increase ◽  
Compression Performance ◽  
Negative Linear Correlation ◽  
Sample Density ◽  
Foaming Temperature ◽  
The Relationship

AbstractThe performance of Polystyrene microporous foaming (PS-MCF) materials is influenced by their microstructures. Therefore, it is essential for industrializing them to investigate the relationship between their microstructure and material properties. In this study, the relationship between the microstructure, compressive property, and thermal conductivity of the PS-MCF materials was studied systematically. The results show that the ideal foaming pressure of PS-MCF materials, obtaining compression performance, is around 20 MPa. In addition, the increase of temperature causes the decrease of sample density. It effects that the compression modulus and strength increase with the decrease of foaming temperature. Because the expansion rate and cell diameter of the PS-MCF materials reduce the thickness of cell wall, they are also negatively correlated with their mechanical properties. Moreover, there is a negative linear correlation between the thermal conductivity and cell rate, whereas the cell diameter is positively correlated with the thermal conductivity.

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

scholarly journals Post-Processing Time Dependence of Shrinkage and Mechanical Properties of Injection-Molded Polypropylene

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Artur Kościuszko ◽  
Dawid Marciniak ◽  
Dariusz Sykutera
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Injection Molding ◽  
Accelerated Aging ◽  
Mold Temperature ◽  
Degree Of Crystallinity ◽  
Injection Mold ◽  
Secondary Crystallization ◽  
Scanning Calorimetry ◽  
Injection Molded

Dimensions of the injection-molded semi-crystalline materials (polymeric products) decrease with the time that elapses from their formation. The post-molding shrinkage is an effect of secondary crystallization; the increase in the degree of polymer crystallinity leads to an increase in stiffness and decrease in impact strength of the polymer material. The aim of this study was to assess the changes in the values of post-molding shrinkage of polypropylene produced by injection molding at two different temperatures of the mold (20 °C and 80 °C), and conditioned for 504 h at 23 °C. Subsequently, the samples were annealed for 24 h at 140 °C in order to conduct their accelerated aging. The results of shrinkage tests were related to the changes of mechanical properties that accompany the secondary crystallization. The degree of crystallinity of the conditioned samples was determined by means of density measurements and differential scanning calorimetry. It was found that the changes in the length of the moldings that took place after removal from the injection mold were accompanied by an increase of 20% in the modulus of elasticity, regardless of the conditions under which the samples were made. The differences in the shrinkage and mechanical properties of the samples resulting from mold temperature, as determined by tensile test, were removed by annealing. However, the samples made at two different injection mold temperature values still significantly differed in impact strength, the values of which were clearly higher for the annealed samples compared to the results determined for the samples immediately after the injection molding.

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