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A method for regulating the crystallization of α-olefin homopolymer by processing conditions

A technology of olefin homopolymer and processing conditions, applied in the field of polymer crystallization, can solve the problems of low crystallization temperature and unfavorable processing and molding, and achieve the effect of shortening crystallization time and improving processing and molding efficiency

Active Publication Date: 2022-05-24
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The crystallization behavior of long-chain α-olefins has been reported in detail in the prior art, but due to the low crystallization temperature of long-chain α-olefin homopolymers, it is not conducive to processing and molding
Moreover, there are few reports on the method of controlling the crystallization time of long-chain α-olefins through processing conditions.

Method used

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  • A method for regulating the crystallization of α-olefin homopolymer by processing conditions
  • A method for regulating the crystallization of α-olefin homopolymer by processing conditions
  • A method for regulating the crystallization of α-olefin homopolymer by processing conditions

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Embodiment 1 The method for preparing α-olefin homopolymers of different crystal forms by regulating and controlling processing conditions, comprising the following steps:

[0036] Long chain alpha-olefin homopolymers were thermally treated using a Linkam hot stage. The temperature was raised to 160°C at 10°C / min and kept for 10min, and then cooled to -30°C at 10°C / min, and the Type II crystal was obtained by crystallization. The samples obtained by cooling and crystallization were characterized by WAXD, such as figure 1 shown. The sample has obvious diffraction signals at 2θ=21° and 23.7°, indicating that Type II crystal form is formed by cooling at 10°C / min.

[0037] The poly-1-tetradecene sample was heat-treated with a Linkam hot stage, heated to 160 °C at 10 °C / min and held for 10 min, then quenched with liquid nitrogen for 30 s and returned to room temperature. The samples obtained by cooling and crystallization were characterized by WAXD, such as figure 2 sho...

Embodiment 2

[0039] Testing was performed using a DSC Q2000 (TAInstrument). Weigh 5 mg of poly-1-hexadecene sample, put it into a crucible, heat it up to 160 °C at 10 °C / min and keep it for 10 minutes, then cool it down to -30 °C at 10 °C / min and keep it for 2 minutes to obtain a Type II crystal sample; Then, the temperature was raised to 90°C and 160°C at 5°C / min, maintained for 10 minutes, and then cooled to 44°C at 10°C / min, and isothermally crystallized to complete crystallization. Relative crystallinity X during isothermal crystallization at 44°C for samples after melting at 90°C and 160°C c Change with time image 3 shown.

[0040] Relative crystallinity X c Calculated by the following formula:

[0041]

Embodiment 3

[0044] Testing was performed using a DSC Q2000 (TA Instrument). Weigh 5 mg of poly-1-octadecene sample, put it into a crucible, heat it up to 160 °C at 10 °C / min and keep it for 10 minutes, then cool it down to -30 °C at 10 °C / min and keep it for 2 minutes to obtain a Type II crystal sample. , and then heated to 110°C and 160°C at 5°C / min respectively and kept for 180min, then cooled to 52°C at 10°C / min and isothermally crystallized to complete crystallization. Relative crystallinity X of samples melted at 110°C and 160°C during isothermal crystallization at 52°C c Change with time Figure 4 shown. from Figure 4 It can be seen that under the same isothermal crystallization temperature conditions, the time for complete crystallization when the melting temperature is 110 °C is shorter than that when the melting temperature is 160 °C, which shows that the method of reducing the melting temperature can effectively shorten the crystallization time.

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Abstract

The invention discloses a method for controlling the crystallization of α-olefin homopolymer through processing conditions, and belongs to the technical field of polymer crystallization. The long-chain α-olefin homopolymer with 12-20 carbon atoms is heated to 160°C and kept for 10 minutes, and the temperature is lowered so that the long-chain α-olefin homopolymer crystallizes to obtain the initial sample; then the temperature is raised to 45-160°C to melt and Keep warm for 1-3600s, then cool down to an isothermal temperature of 10-75°C at 10°C / min; apply a shear strain rate of 0-5s ‑1 , a flow field with a shear time of 0‑5s, and crystallization at the isothermal crystallization temperature. In the present invention, there are obvious differences in the crystallization time of long-chain α-olefin homopolymers under different processing conditions, which shows that processing conditions have a greater impact on the crystallization time of long-chain α-olefin homopolymers, and provides a basis for improving processing and molding efficiency. a feasible solution.

Description

technical field [0001] The invention belongs to the technical field of polymer crystallization, and in particular relates to a method for regulating the crystallization of an alpha-olefin homopolymer through processing conditions. Background technique [0002] Long-chain alpha-olefin homopolymers are unique comb polymers in which both the backbone and side chains may crystallize, depending on the length of the side chains. The crystals formed by main chain crystallization are Type I crystals. Type I crystal form is obtained by melt quenching followed by heating to a temperature range of 5-30°C below the melting temperature. The Type II crystal form formed by the orderly arrangement of side chains can be directly obtained by cooling and crystallization from the melt. The crystallinity of long-chain α-olefin homopolymers increases with increasing side chain length. The crystallization behavior of long-chain alpha-olefins has been reported in detail in the prior art, but the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08J3/00C08L23/24
CPCC08J3/00C08J2323/24
Inventor 马哲娄雅卉赵芮君曲春静
Owner TIANJIN UNIV
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