An unusual promotion of γ-crystals in metallocene-made isotactic polypropylene from orientational relaxation and favorable temperature window induced by shear

Wang, Yan; Zhao, Jianqing; Qu, Minjie; Guo, Jing; Yang, Shen; Lei, Jun; Xu, Jia‐Zhuang; Chen, Yanhui; Li, Zhong‐Ming; Hsiao, Benjamin S.

doi:10.1016/j.polymer.2017.11.040

Cited by 15 publications

(10 citation statements)

References 41 publications

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“…The orthorhombic γ-iPP was first prepared by Addink and Beintema 4 from low-molecular-weight iPP at high pressure and in random copolymers with less regular chains, although this modification was observed in commercial injection-molded products as well due to the higher shearing conditions. 5 Recently, Lotz et al 6 discovered another new form, ε-iPP. The thermodynamically stable polymorph is α-iPP; however, also the β-modification can develop in significant amounts during processing if favorable conditions are present.…”

Section: Introductionmentioning

confidence: 99%

Effect of N,N′-Dicyclohexyldicarboxamide Homologues on the Crystallization and Properties of Isotactic Polypropylene

et al. 2021

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Application of nucleating agents is the most versatile and industrially applied way to manipulate the crystalline structure of isotactic polypropylene (iPP). Various materials possess a nucleating effect, but from the viewpoint of dispersibility, the partially soluble ones are the most advantageous. Our objective was to synthesize new N , N ′-dicyclohexyldicarboxamide homologues and study their applicability as nucleating agents in iPP. Carbon-13 nuclear magnetic resonance ( 13 C NMR) and infrared spectroscopy were used to prove that the synthesis reactions were successful. Thermal stability of the compounds was investigated with simultaneous thermal analysis. Nucleating efficiency and solubility were characterized by polarized light microscopy and differential scanning calorimetry. Polarized light microscopy was also applied to study the effect of novel additives on the morphology of iPP. The properties, important from the viewpoint of applicability, were also investigated. Tensile tests were performed to characterize the main mechanical properties, and standard haze measurements were performed to characterize optical properties. It can be concluded that the investigated compounds are partially soluble nucleating agents and influence the crystalline structure of iPP. Most of the studied compounds have a moderate nucleating efficiency, but a very interesting dendritic structure develops in their presence. Two of them proved to be non-selective β-nucleating agents, which result in a remarkable improvement of impact resistance and higher opacity.

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Section: Introductionmentioning

confidence: 99%

Effect of N,N′-Dicyclohexyldicarboxamide Homologues on the Crystallization and Properties of Isotactic Polypropylene

et al. 2021

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“…Titanium dioxide (TiO 2 ) is one of the most commercially white pigments . It has been widely used in many fields, such as paints, coatings, fillers for plastic and paper, chemical fibers, rubbers, and inks, due to its splendid properties of high refractive index, low density, high brightness, and hiding power …”

Section: Introductionmentioning

confidence: 99%

Mechanism of synthesis of anatase TiO₂ pigment from low concentration of titanyl sulfuric–chloric acid solution under hydrothermal hydrolysis

Tian

Liu

Wang

et al. 2019

J Chinese Chemical Soc

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In order to investigate the influence of Cl−/SO42− molar ratios and hydrolysis temperature on the hydrolysis process and TiO2 pigment, H2TiO3 was prepared with a low concentration of titanyl sulfuric–chloric acid solution by hydrothermal hydrolysis. Under the optimal hydrolysis conditions, 1.5–2.2 μm of H2TiO3 samples were achieved. After doping and calcination, anatase TiO2 pigments demonstrated excellent performance: the achromic ability of tinctorial strength (TCS) and blue phase index (SCX) were 1,429 and 4.07, respectively. As hydrolysis was a significant step in the process, the structure was simplified to a periodic structure of Ti[OH](H2O)3Cl(SO4) to simulate the cluster structures. Based on experimental results and density functional theory (DFT) calculation, the hydrolysis mechanism was presumed to be a process of anionic (OH−, Cl− and SO42−) competition reaction to explain the formation of anatase‐type H2TiO3, and the crystal growth direction of H2TiO3 was also confirmed to be a (OA) and b (OB).

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“…The β form, which is produced during the crystallization of a sheared melt, crystallization in a temperature gradient, or during the addition of certain nucleating agents, has to be achieved under well-controlled conditions in iPP products [8]. The γ phase is usually formed at high pressure and favored by the low-molecular-weight fraction of polydisperse melts [9,10]. In addition to these crystal phases, a mesomorphic phase could be obtained at high cooling rates, which is usually formed during high-speed spinning [11,12].…”

Section: Introductionmentioning

confidence: 99%

Structure and Properties of a Metallocene Polypropylene Resin with Low Melting Temperature for Melt Spinning Fiber Application

Zhang

Wang

et al. 2019

Polymers

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An isotactic polypropylene (iPP-1) resin with low melting temperature (Tm) is synthesized by a metallocene catalyst and investigated for melt-spun fiber applications. The structure, thermal and mechanical properties, and feasibility of producing fibers of a commercial metallocene iPP (iPP-2) and a conventional Ziegler–Natta iPP (iPP-3) are carefully examined for comparison. Tm of iPP-1 is about 10 °C lower than the other two samples, which is well addressed both in the resin and the fiber products. Besides, the newly developed iPP-1 possesses higher isotacticity and crystallinity than the commercial ones, which assures the mechanical properties of the fiber products. Thanks to the addition of calcium stearate, its crystal grain size is smaller than those of the two other commercial iPPs. iPP-1 shows a similar rheological behavior as the commercial ones and good spinnability within a wide range of take-up speeds (1200–2750 m/min). The tensile property of fibers from iPP-1 is better than commercial ones, which can fulfill the application requirement. The formation of the mesomorphic phase in iPP-1 during melt spinning is confirmed by the orientation and crystallization investigation with wide angle X-ray diffraction (WAXD), which is responsible for its excellent processing capability and the mechanical properties of the resultant fibers. The work may provide not only a promising candidate for the high-performance PP fiber but also a deep understanding of the formation mechanism of the mesomorphic phase during fiber spinning.

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An unusual promotion of γ-crystals in metallocene-made isotactic polypropylene from orientational relaxation and favorable temperature window induced by shear

Cited by 15 publications

References 41 publications

Effect of N,N′-Dicyclohexyldicarboxamide Homologues on the Crystallization and Properties of Isotactic Polypropylene

Effect of N,N′-Dicyclohexyldicarboxamide Homologues on the Crystallization and Properties of Isotactic Polypropylene

Mechanism of synthesis of anatase TiO₂ pigment from low concentration of titanyl sulfuric–chloric acid solution under hydrothermal hydrolysis

Structure and Properties of a Metallocene Polypropylene Resin with Low Melting Temperature for Melt Spinning Fiber Application

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An unusual promotion of γ-crystals in metallocene-made isotactic polypropylene from orientational relaxation and favorable temperature window induced by shear

Cited by 15 publications

References 41 publications

Effect of N,N′-Dicyclohexyldicarboxamide Homologues on the Crystallization and Properties of Isotactic Polypropylene

Effect of N,N′-Dicyclohexyldicarboxamide Homologues on the Crystallization and Properties of Isotactic Polypropylene

Mechanism of synthesis of anatase TiO2 pigment from low concentration of titanyl sulfuric–chloric acid solution under hydrothermal hydrolysis

Structure and Properties of a Metallocene Polypropylene Resin with Low Melting Temperature for Melt Spinning Fiber Application

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Mechanism of synthesis of anatase TiO₂ pigment from low concentration of titanyl sulfuric–chloric acid solution under hydrothermal hydrolysis