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Method for improving heat stability of polypropylene plastic

A polypropylene plastic and thermal stability technology, applied in the field of physical modification of polypropylene fiber, can solve the problems of uneven physical and chemical properties, not being well utilized, complex lignin structure, etc., and achieve simple process and good quality Application prospect, low cost effect

Inactive Publication Date: 2014-05-14
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At the same time, due to many problems such as complex structure, uneven physical and chemical properties, difficulty in separation and extraction, and easy condensation of lignin, it has not been well utilized so far.

Method used

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  • Method for improving heat stability of polypropylene plastic
  • Method for improving heat stability of polypropylene plastic
  • Method for improving heat stability of polypropylene plastic

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The lignin powder dried in vacuum at 70°C for 24h and polypropylene were mixed evenly in a high-speed mixer at a mass ratio of 5:95, and the mixed materials were melt-blended in a micro-blender at 180°C to obtain a uniformly mixed Blend: the above blend is added to the feed hopper of the micro injection molding machine and melted at 190°C, and the mixture melt is injected into the dumbbell-shaped mold under the pressure of the injection molding machine, and the temperature of the mold is set at 30°C. Cool to obtain a dumbbell-shaped blended spline. Among them, the crystallization performance of the blended spline is improved, the crystallinity is 50%, the thermal stability in nitrogen is improved, and the residual rate (12.73%) in the air at 350 °C for 1 hour is 42% higher than that of pure pp (8.98%).

Embodiment 2

[0024] The lignin powder dried in vacuum at 70°C for 24 hours and polypropylene were mixed evenly in a high-speed mixer at a mass ratio of 10:90, and the mixed materials were melt-blended in a micro-blender at 180°C to obtain a uniformly mixed Blend: Add the above blend into the feed hopper of the micro-injection molding machine and melt it at 200°C, and inject the melted mixture into the strip mold under the pressure of the injection molding machine, and the temperature of the mold is set at 40°C , cooling to obtain a long blended spline. Among them, the crystallization performance of the blended spline is improved, the crystallinity is 54%, the thermal stability in nitrogen is improved, and the residual rate (14.83%) in the air at 350 ° C for 1 hour is 65% higher than that of pure pp (8.98%).

Embodiment 3

[0026] The lignin powder dried in vacuum at 70°C for 24h and polypropylene were mixed evenly in a high-speed mixer at a mass ratio of 15:85, and the mixed materials were melt-blended at 170°C in a micro-blender to obtain a uniformly mixed Blend: Add the above blend into the feed hopper of the micro-injection molding machine and melt it at 200°C, and inject the mixture melt into the dumbbell-shaped mold under the pressure of the injection molding machine, and the temperature of the mold is set at 30°C. Cool to obtain a dumbbell-shaped blended spline. Among them, the crystallization performance of the blended spline is improved, the crystallinity is 62%, the thermal stability in nitrogen is improved, and the residual rate (15.47%) in the air at 350 ° C for 1 hour is 72% higher than that of pure pp (8.98%).

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Abstract

The invention relates to a method for improving the heat stability of polypropylene plastic. The method comprises the steps of (1) uniformly mixing lignin and polypropylene according to a mass ratio of (5:95)-(20:80), and performing melt blending on a mixture under the temperature of 150-250 DEG C to obtain a uniformly mixed blend; and (2) adding the blend into a material feeding hopper of a micro injection molding machine for melting under the temperature of 170-240 DEG C, injecting a mixture melt into a mold, and cooling to obtain a blended sample. The technology of the method disclosed by the invention is simple; an operating method is simple, and the cost is low; the lignin can realize a certain heterogeneous nucleation function in a polypropylene crystallization process, so that the crystallinity and the crystallization property of polypropylene can be improved; meanwhile, due to the influence of a three-dimensional meshed structure of the lignin, the heat resistance of a composite material can be improved; and the method can be popularized industrially and has a good application prospect.

Description

technical field [0001] The invention belongs to the field of physical modification of polypropylene fibers, in particular to a method for improving the thermal stability of polypropylene plastics. Background technique [0002] Polypropylene is a thermoplastic resin obtained by the polymerization of propylene. It has three configurations: isotactic, random and syndiotactic. Industrial products use isotactic as the main component. The melting temperature of polypropylene is about 174°C, and the density is about 0.91g / cm 3 , is the lightest general-purpose plastic, has the advantages of high strength, high hardness, wear resistance, bending fatigue resistance, corrosion resistance, and easy processing and molding. key issues in the field. Lignin is a natural polymer compound that is second only to cellulose in the amount of synthesis and existence in nature. Together with cellulose and hemicellulose, lignin constitutes the main body of plants and is the most abundant renewab...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08L23/12C08L97/00B29C45/78
CPCB29C45/78B29C2945/76531C08L23/12C08L97/02C08L2201/08C08L2205/24
Inventor 余木火陈磊刘淑萍张文辉张静洁王海风韩克清荣怀苹覃辉林严斌王丹景鹏展张建军柯盛包李双江王会峰吴玉霞
Owner DONGHUA UNIV
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