Improved polypropylene and method for improving yield strength and toughness of polypropylene

A technology of polypropylene and isotactic polypropylene, which is applied in the field of polypropylene materials, can solve problems such as important influences that cannot be questioned, and achieve the effect of improving yield toughness

Inactive Publication Date: 2012-06-27
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] So far, people have not fully understood the factors that affect the mechanical properties of polypropylene materials, but the important influence of the crystal phase transition between β and α under stress on the mechanical properties of materials is unquestionable, and the crystallization induced by isothermal crystallization at different temperatures The phase change can also affect the mechanical properties of PP (such as fracture strength, tensile toughness, elongation at break, etc.), so the improvement of the mechanical properties of the material can be attributed to the crystal structure and its growth and perfection. The mechanical properties of the materials measured by elongation are also different

Method used

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  • Improved polypropylene and method for improving yield strength and toughness of polypropylene
  • Improved polypropylene and method for improving yield strength and toughness of polypropylene

Examples

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Effect test

Embodiment 1

[0017] Take by weighing one hundred kilograms of isotactic polypropylene (brand T1701, Sinopec Beijing Yanshan Petrochemical Company), take by weighing DCNDCA nucleating agent 50g according to the amount of its mass percentage 0.05%, the polypropylene that takes by weighing and DCNDCA nucleating agent are at room temperature After being mixed evenly at high speed, it is sent to the feeding hopper of the twin-screw extrusion granulation unit. The temperature of the mixing section of the unit is set at 210 degrees Celsius, and the temperature of the machine head is set at 190 degrees Celsius. Polypropylene pellets containing 0.05% by mass of DCNDCA nucleating agent were obtained. The pellets were melted and then extruded into pipes. The crystallization temperature was controlled at 135° C., and the yield strength was 21.4 MPa when tested under tension.

Embodiment 2

[0019] Take by weighing one hundred kilograms of isotactic polypropylene (brand T1701, Sinopec Beijing Yanshan Petrochemical Company), take by weighing DCNDCA nucleating agent 50g according to the amount of its mass percentage 0.05%, the polypropylene that takes by weighing and DCNDCA nucleating agent are at room temperature After being mixed evenly at high speed, it is sent to the feeding hopper of the twin-screw extrusion granulation unit. The temperature of the mixing section of the unit is set at 210 degrees Celsius, and the temperature of the machine head is set at 190 degrees Celsius. Polypropylene pellets containing 0.05% by mass of DCNDCA nucleating agent were obtained. The pellets were melted and then extruded into pipes. The crystallization temperature was controlled at 140° C., and the yield strength was 23.9 MPa when tested under tension.

Embodiment 3

[0021] Take by weighing one hundred kilograms of isotactic polypropylene (brand T1701, Sinopec Beijing Yanshan Petrochemical Company), take by weighing DCNDCA nucleating agent 200g according to the amount of its mass percentage 0.2%, the polypropylene that takes by weighing and DCNDCA nucleating agent are at room temperature After being mixed evenly at high speed, it is sent to the feeding hopper of the twin-screw extrusion granulation unit. The temperature of the mixing section of the unit is set at 210 degrees Celsius, and the temperature of the machine head is set at 190 degrees Celsius. Polypropylene granules containing 0.2% by mass of DCNDCA nucleating agent were obtained, and the granules were melted and then injection-molded into thin sheets. The temperature of the mold was controlled at room temperature 135° C., and the yield strength was 19.3 MPa when tested under tension.

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Abstract

The invention discloses an improved polypropylene and a method for improving yield strength and toughness of polypropylene. The improved polypropylene is characterized in that isotactic polypropylene and N,N'-dicyclohexyl-2,6-naphthalene dicarboxamide (DCNDCA) which is utilized as a single nucleating agent of isotactic polypropylene and has a molecular structural formula shown in the formula 1 are mixed uniformly, then are subjected to melt blending and are subjected to isothermal crystallization at a temperature of 135 to 140 DEG C, wherein an addition amount of the nucleating agent of DCNDCA is greater than 0 and is less than or equal to 1% of the mass of the isotactic polypropylene. Through adjustment of a nucleating agent content and isothermal crystallization at different temperatures, the optimum condition capable of improving yield strength and toughness of polypropylene is acquired. The method provided by the invention improves yield strength and toughness of polypropylene thereby promoting polypropylene material development and industrial application.

Description

technical field [0001] The present invention relates to a polypropylene material, more specifically, to an improved polypropylene material and a method for increasing the yield toughness of polypropylene. Background technique [0002] Isotactic polypropylene (iPP) is a semi-crystalline polymer widely used in industry and commerce. Since the final morphology and material properties of the polymer are largely affected by the processing method, iPP can form a variety of crystal forms under different conditions, for example, it can form the monoclinic α-type crystal phase and hexagonal crystal The β-type crystal phase of the system. β-PP has attracted extensive attention because of its unique thermal and mechanical properties. The toughness of PP materials with high β-crystal content is significantly higher than that of PP materials with high α-crystal content. Usually, in order to obtain a sufficiently high content of β-crystals in polypropylene materials or products, or to c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08L23/12C08K5/20
Inventor 蔡紫薇李景庆蒋世春
Owner TIANJIN UNIV
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