On-line measuring method and apparatus for degree of crystallization of polymer used for injection molding

Abstract

The invention discloses an on-line measuring method and apparatus for the degree of crystallization of a polymer used for injection molding. The method comprises the following steps: 1) acquiring the density of a complete crystal region of a polymer and the temperature-density curve of a complete noncrystal region of the polymer; 2) acquiring the density of a complete noncrystal region of a polymer melt in a die; 3) employing supersonic wave for real time detection of the current density of the polymer melt in the die and obtaining the real time degree of crystallization of the polymer melt according to the current density detected, the density of the complete crystal region and the density of the complete noncrystal region. The apparatus provided in the invention comprises a sensor unit, a data acquisition unit and a central processing unit, wherein, the sensor unit comprises a supersonic wave detection unit and a temperature sensor, the supersonic wave detection unit comprises a supersonic wave emitting unit and a supersonic wave receiving unit, and the temperature sensor and the supersonic wave receiving unit are respectively connected with the central processing unit through the data acquisition unit. The invention enables on-line measuring of the degree of crystallization of a polymer in the process of injection molding to be realized; the apparatus provided in the invention has the advantages of a low price and convenient usage.

Description

technical field [0001] The invention relates to the field of polymer injection molding, in particular to an online measurement method and device for polymer crystallinity in the injection molding process. Background technique [0002] Injection molding is the most important means of producing high-performance polymer products. According to statistics, more than 80% of engineering polymer products are produced by injection molding process. During the injection molding production process, the crystallinity of the polymer formed and finally solidified in the product directly affects the physical and mechanical properties of the product such as strength, stiffness, thermal properties, and transparency. For example, when the crystallinity of polypropylene increases from 70% to 95%, its tensile strength can be increased from 27.5MPa to 42MPa. When the crystallinity of polypropylene is 70% and 95%, respectively, its notched impact strength is 15.2kg cm / cm2 and 4.77kg cm / cm2, so th...

AI Technical Summary

Problems solved by technology

However, this technical solution is only suitable for transparent materials, and most crystalline polymers are translucent or opaque. At the same time, this device also has problems such as expensive equipment, cumbersome use, and poor versatility. It has certain limitations in industrial applications. Limitations, currently mostly used in laboratory research

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