Method for regulating and controlling crystal morphology of butene / pentene copolymer

Abstract

The invention relates to the technical field of polymer crystallization, in particular to a method for regulating and controlling the crystal morphology of a butene / pentene copolymer. And heating the butylene / pentene copolymer to 180 DEG C, keeping the temperature for 10 minutes, cooling to an isothermal crystallization temperature, and keeping the temperature until the butylene / pentene copolymer is completely crystallized, thereby realizing regulation and control on the crystal morphology of the butylene / pentene copolymer. According to the invention, by adjusting the crystallization temperature and the content of a pentene copolymerization unit, the arrangement and stacking state of a macromolecular chain in the crystallization process is changed, so that different crystal morphologies are formed, and the crystal morphologies are related to the crystal form of the crystal. Meanwhile, the annular spherocrystal with the lamellar crystal synergistically twisted in the radial direction of the spherocrystal is obtained, and a feasible method is provided for morphology regulation and control and crystal form transformation regulation and control of existing butenyl polymer crystals.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer crystallization, and particularly to a method for regulating the crystal morphology of butene / pentene copolymers. Background Art

[0002] Spherulitic banding is a special spherulite morphology with an internal annular banded structure. The formation of such spherulitic banding may be due to the cooperative twisting of macromolecular chains along the radial direction of the spherulite during the melt crystallization process. Butene-based polymers are typical polymorphic polymers with relatively complex polymorphic transitions. The trigonal phase crystals (form I / I') are the thermodynamically most stable crystal form of poly-1-butene, but melt crystallization usually forms metastable tetragonal phase crystals with kinetic advantages, which then spontaneously transform into thermodynamically stable trigonal phase crystals at room temperature through polymorphic transformation. Although extensive research has been carried out on the crystallization behavior of butene-based polymers, it mainly focuses on the regulation of the crystallization crystal form and polymorphic transformation of butene-based polymers, and the research on the crystal morphology controlled by thermodynamics and kinetics has progressed slowly. This may be because usually, polybutene materials form spherulites during melt or solution crystallization, and introducing copolymer units or blending components only changes the spherulite growth rate and crystal size, hardly changes the crystal morphology, making it difficult to discuss and regulate the crystal morphology of butene polymers, and also difficult to correspond the crystal structure to its morphology. Therefore, the present invention provides a method for regulating the crystal morphology of butene / pentene copolymers, which is of great significance to the technical field of polymer crystallization. Summary of the Invention

[0003] Based on the above, the present invention provides a method for regulating the crystal morphology of butene / pentene copolymers.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention, a method for regulating the crystal morphology of butene / pentene copolymers, comprises the following steps:

[0006] Heat the butene / pentene copolymer to 180 °C and hold for 10 min, then cool to the isothermal crystallization temperature and hold until complete crystallization, thereby realizing the regulation of the crystal morphology of the butene / pentene copolymer.

[0007] Another technical solution of the present invention, a method for regulating the melting temperature of butene / pentene copolymers, realizes the regulation of the melting temperature of butene / pentene copolymers by using the above method for regulating the crystal morphology of butene / pentene copolymers.

[0008] The present invention discloses the following technical effects:

[0009] The present invention provides a method for regulating the crystal morphology of butene / pentene copolymer by crystallization temperature or pentene copolymer unit content, which makes up for the blank of the non-adjustable crystal morphology in the crystallization and molding process of existing butene-based copolymers. In the present invention, by adjusting factors such as crystallization temperature and pentene copolymer unit, the arrangement and stacking state of polymer chains during crystallization are changed, so as to form different crystal morphologies, and this crystal morphology is related to its crystallization crystal form. At the same time, ring-banded spherulites are obtained due to the cooperative torsion of lamellae along the radial direction of spherulites, providing a feasible method for regulating the crystal morphology and crystal form transformation of existing butene-based polymers.

[0010] The technical method provided by the present invention is applicable to butene / pentene copolymers with pentene copolymer unit content of 4.0 - 36.1 mol%, and the crystal morphology of butene / pentene copolymer can be changed by changing the isothermal crystallization temperature and pentene copolymer unit content. The present invention provides an effective way to regulate the crystal morphology of butene / pentene copolymer. Brief Description of the Drawings

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings without creative efforts based on these drawings.

[0012] Figure 1 It is the crystal morphology of the butene / pentene copolymer with a pentene copolymer unit content of 7.6 mol% in Example 1 of the present invention after isothermal crystallization at 70 °C and 80 °C.

[0013] Figure 2 It is the crystal morphology of the butene / pentene copolymer with a pentene copolymer unit content of 12.3 mol% in Example 2 of the present invention after isothermal crystallization at 55 °C and 75 °C.

[0014] Figure 3 It is the crystal morphology of the butene / pentene copolymer with a pentene copolymer unit content of 17.6 mol% in Example 3 of the present invention after isothermal crystallization at 54 °C and 66 °C.

[0015] Figure 4 It is the crystal morphology of the butene / pentene copolymer with a pentene copolymer unit content of 26.9 mol% in Example 4 of the present invention after isothermal crystallization at 48 °C and 60 °C.

[0016] Figure 5 It is the crystal morphology of the butene / pentene copolymer with a pentene copolymer unit content of 36.1 mol% in Example 5 of the present invention after isothermal crystallization at 32 °C and 44 °C.

[0017] Figure 6Morphology of the crystals of the butene / pentene copolymers with pentene copolymerization unit contents of 4.0 mol% and 7.6 mol% in Example 6-7 of the present invention after isothermal crystallization at 75°C.

[0018] Figure 7 Melting process of the butene / pentene copolymer with a pentene copolymerization unit content of 36.1 mol% in Example 5 of the present invention after isothermal crystallization at 32°C.

[0019] Figure 8 Melting process of the butene / pentene copolymer with a pentene copolymerization unit content of 36.1 mol% in Example 8 of the present invention after isothermal crystallization at 48°C.

[0020] Figure 9 Morphology of the crystals of the butene homopolymer in Comparative Example 1 of the present invention after isothermal crystallization at 80°C. Detailed Description of the Invention

[0021] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as limiting the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0022] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0024] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0025] The terms "comprising", "including", "having", "containing", etc. as used herein are all open-ended terms, meaning including but not limited to.

[0026] The spontaneous phase transition from form II to form I can be affected by the internal stress of the polymer. Therefore, the cooperative twisting effect that forms ring-banded spherulites can affect the phase transition from the tetragonal phase to the trigonal phase of the butene polymer. Thus, a method for controlling the crystal morphology of butene-based polymers by the crystallization temperature is developed. Obtaining ring-banded spherulites with cooperative twisting of lamellae can control the crystallization morphology and crystal form transition of butene polymers.

[0027] The first aspect of the present invention provides a method for controlling the crystal morphology of a butene / pentene copolymer, comprising the following steps:

[0028] Heat the butene / pentene copolymer to 180 °C and hold for 10 min, then cool to the isothermal crystallization temperature and hold until complete crystallization, thereby realizing the control of the crystal morphology of the butene / pentene copolymer.

[0029] In a preferred embodiment of the present invention, the content of the pentene copolymer unit in the butene / pentene copolymer is 4.0 - 36.1 mol%.

[0030] In a preferred embodiment of the present invention, the molecular weight of the butene / pentene copolymer is 1.0 - 1.8×10 6 , and the molecular weight distribution is 1.8 - 2.3; the proportion of mmmm isotactic pentads in the butene / pentene copolymer is between 94% and 97%.

[0031] In a preferred embodiment of the present invention, the heating rate is 10 °C / min.

[0032] In a preferred embodiment of the present invention, the cooling rate is 30 °C / min.

[0033] In a preferred embodiment of the present invention, the isothermal crystallization temperature is 32 - 90 °C.

[0034] The time for holding at the isothermal crystallization temperature until complete crystallization is 1 - 16500 s.

[0035] In order to observe the crystal morphology of the butene / pentene copolymer, before controlling the crystal morphology of the butene / pentene copolymer, it further includes the steps of placing the butene / pentene copolymer on a glass slide, heating to 180 °C at a rate of 20 °C / min, covering with a cover glass, and holding at 180 °C for 10 min, and then cooling to room temperature to prepare an initial sample.

[0036] The method for regulating the crystal morphology of the butene / pentene copolymer in the present invention is reversible, that is, the butene / pentene copolymer with regulated crystal morphology is heated to the melting temperature, and then kept at the isothermal crystallization temperature until complete crystallization, and the crystal morphology before melting can be reproduced again.

[0037] In the second aspect of the present invention, a method for regulating the melting temperature of the butene / pentene copolymer is provided, and the melting temperature of the butene / pentene copolymer is regulated by using the above method for regulating the crystal morphology of the butene / pentene copolymer.

[0038] The technical solutions of the present invention are all conventional solutions in the art unless otherwise specified. The reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0039] In the examples of the present invention, the content of the pentene copolymerization unit in the butene / pentene copolymer is 4.0 - 36.1 mol%, the molecular weight is between 1.0 - 1.8×10 6 , the molecular weight distribution is between 1.8 - 2.3, and the proportion of the mmmm isotactic pentad is between 94% - 97%.

[0040] The technical solutions provided by the present invention will be described in detail below with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

[0041] Example 1

[0042] A butene / pentene copolymer with a pentene copolymerization unit content of 7.6 mol% (molecular weight 1.57×10 6 , molecular weight distribution 1.90) was heat-treated using a Linkam hot stage. The sample was placed on a glass slide, heated to 180°C at a rate of 20°C / min, covered with a cover glass, and kept at 180°C for 10 min, and then naturally cooled to room temperature to obtain an initial sample for polarized light testing that was flat and bubble-free. Subsequently, the Linkam hot stage was used in combination with a polarized light microscope, heated to 180°C at a rate of 10°C / min and kept at 180°C for 10 min, and then cooled to 70°C and 80°C at a rate of 30°C / min respectively for isothermal crystallization until complete crystallization. The crystal morphologies of the sample after isothermal crystallization at 70°C and 80°C are as Figure 1 shown. As can be seen from Figure 1 , the sample formed spherulites with a black cross extinction when isothermally crystallized at 70°C. The crystal morphology changed significantly during isothermal crystallization at 80°C, and ring-banded spherulites with periodic changes formed outside the spherulites with a black cross extinction. This shows that the crystal morphology can be effectively controlled by changing the temperature method.

[0043] Example 2

[0044] Using a Linkam hot stage, a butene / pentene copolymer with a pentene comonomer content of 12.3 mol% (molecular weight 1.78×10 6 , molecular weight distribution 2.12) was heat-treated. The sample was placed on a glass slide, heated to 180 °C at 20 °C / min, covered with a coverslip, and held at 180 °C for 10 min, then naturally cooled to room temperature to obtain an initial sample for polarized light testing that was flat and bubble-free. Subsequently, the Linkam hot stage was used in conjunction with a polarized light microscope, heated to 180 °C at 10 °C / min and held for 10 min, and then cooled to 55 °C and 75 °C at 30 °C / min respectively for isothermal crystallization until complete crystallization. The crystal morphologies of the sample after isothermal crystallization at 55 °C and 75 °C are as shown in Figure 2 . As can be seen from Figure 2 , the sample formed spherulites with a black cross extinction when isothermally crystallized at 55 °C. There were obvious changes in the crystal morphology during isothermal crystallization at 75 °C. The crystal morphology could be divided into two parts. There were ring-banded spherulites with periodic changes formed outside the spherulites with a black cross extinction, or there were only ring-banded spherulites with periodic changes. This shows that by changing the temperature, the crystal morphology can be effectively controlled.

[0045] Example 3

[0046] Using a Linkam hot stage, a butene / pentene copolymer with a pentene comonomer content of 17.6 mol% (molecular weight 1.2×10 6 , molecular weight distribution 1.87) was heat-treated. The sample was placed on a glass slide, heated to 180 °C at 20 °C / min, covered with a coverslip, and held at 180 °C for 10 min, then naturally cooled to room temperature to obtain an initial sample for polarized light testing that was flat and bubble-free. Subsequently, the Linkam hot stage was used in conjunction with a polarized light microscope, heated to 180 °C at 10 °C / min and held for 10 min, and then cooled to 54 °C and 66 °C at 30 °C / min respectively for isothermal crystallization until complete crystallization. The crystal morphologies of the sample after isothermal crystallization at 54 °C and 66 °C are as shown in Figure 3 . As can be seen from Figure 3 , the sample formed spherulites with a black cross extinction when isothermally crystallized at 54 °C. There were obvious changes in the crystal morphology during isothermal crystallization at 66 °C. Ring-banded spherulites with periodic changes were formed outside the spherulites with a black cross extinction. This shows that by changing the temperature, the crystal morphology can be effectively controlled.

[0047] Example 4

[0048] Using a Linkam hot stage, a butene / pentene copolymer with a pentene comonomer content of 26.9 mol% (molecular weight 1.03×10 6, (molecular weight distribution 1.91) was heat-treated. The sample was placed on a glass slide, heated to 180 °C at a rate of 20 °C / min, covered with a cover glass, and kept at 180 °C for 10 min, and then naturally cooled to room temperature to obtain an initial sample for polarized light testing that was flat and bubble-free. Subsequently, the Linkam hot stage was used in combination with a polarized light microscope, heated to 180 °C at a rate of 10 °C / min and kept at this temperature for 10 min, and then cooled to 48 °C and 60 °C at a rate of 30 °C / min respectively for isothermal crystallization until complete crystallization. The crystal morphologies of the samples after isothermal crystallization at 48 °C and 60 °C are as Figure 4 shown. As can be seen from Figure 4 , the sample formed spherulites with black cross extinction and granular crystals during isothermal crystallization at 48 °C. The granular crystals obtained during isothermal crystallization at 66 °C were more obvious. This shows that the crystal morphology can be effectively controlled by changing the temperature method.

[0049] Example 5

[0050] The Linkam hot stage was used to heat-treat a butene / pentene copolymer with a pentene copolymer unit content of 36.1 mol% (molecular weight 1.11×10 6 , molecular weight distribution 2.0). The sample was placed on a glass slide, heated to 180 °C at a rate of 20 °C / min, covered with a cover glass, and kept at 180 °C for 10 min, and then naturally cooled to room temperature to obtain an initial sample for polarized light testing that was flat and bubble-free. Subsequently, the Linkam hot stage was used in combination with a polarized light microscope, heated to 180 °C at a rate of 10 °C / min and kept at this temperature for 10 min, and then cooled to 32 °C and 40 °C at a rate of 30 °C / min respectively for isothermal crystallization until complete crystallization. The crystal morphologies of the samples after isothermal crystallization at 32 °C and 44 °C are as Figure 5 shown. As can be seen from Figure 5 , the sample mainly formed spherulites with black cross extinction and a small amount of granular crystals during isothermal crystallization at 32 °C. The crystal morphology changed significantly during isothermal crystallization at 44 °C, with the spherulites decreasing and the granular crystals increasing. This shows that the crystal morphology can be effectively controlled by changing the temperature method.

[0051] Example 6

[0052] The difference from Example 2 is only that the pentene copolymer unit content of the sample is 4.0 mol%. Figure 6 shows the crystal morphology of a butene / pentene copolymer with a pentene copolymer unit content of 4.0 mol% after isothermal crystallization at 75 °C ( Figure 6BP04.0 indicates that the pentene comonomer content in the butene / pentene copolymer is 4.0 mol%, and BP07.6 indicates that the pentene comonomer content in the butene / pentene copolymer is 7.6 mol%). It was found that the isothermal crystallization of the butene / pentene polymer with 4.0 mol% pentene comonomer only formed spherulites with a black cross extinction, and no ring-banded spherulites were formed.

[0053] Example 7

[0054] The difference from Example 2 is only that the pentene comonomer content of the sample is 7.6 mol%. Figure 6 The crystal morphology after isothermal crystallization at 75 °C of the copolymer with 7.6 mol% pentene comonomer content is shown. It was found that the isothermal crystallization of the butene / pentene polymer with 7.6 mol% pentene comonomer formed spherulites with a black cross extinction and there were also ring-banded spherulites with periodic changes on the periphery.

[0055] From the results of Examples 6 - 7, it can be seen that the crystal morphology of the butene / pentene copolymer can be changed by the method of regulating the pentene comonomer content in the present invention.

[0056] Example 8

[0057] The difference from Example 5 is only that the isothermal crystallization temperature is 48 °C, and after crystallization, it is heated to melting at a rate of 10 °C / min.

[0058] Figure 7 The change in crystal morphology during the process of heating to melting at a rate of 10 °C / min after isothermal crystallization at 32 °C of the butene / pentene copolymer with 36.1 mol% pentene comonomer content is shown. From Figure 7 it can be seen that melting starts when the temperature rises to 92 °C and is completely melted until the temperature is raised to 107 °C.

[0059] Figure 8 The change in crystal morphology during the process of heating to melting at a rate of 10 °C / min after isothermal crystallization at 48 °C of the butene / pentene copolymer with 36.1 mol% pentene comonomer content is shown. From Figure 8 it can be seen that as the temperature rises, there are two stages of melting for the polymer crystals. Under lower temperature conditions (68 °C), the granular crystals melt first; as the temperature rises to around 90 °C, the spherulites start to melt.

[0060] The butene / pentene copolymer with a pentene copolymer unit content of 36.1 mol% mainly forms a trigonal phase (form I / I') during isothermal crystallization at 15 - 60 °C, and the crystal form formed has an obvious temperature dependence. Crystallization at low temperatures is prone to indirectly obtaining form I with a higher melting temperature through a phase transition, while crystallization at high temperatures tends to directly melt-crystallize to form form I' with a lower melting temperature. The butene / pentene copolymer mainly forms spherulites with a Maltese cross extinction during isothermal crystallization at 32 °C and has a higher melting temperature. While during isothermal crystallization at 48 °C, the granular crystals increase and melt first, the spherulites decrease and have a higher melting temperature. This shows that different trigonal phases have different crystal morphologies.

[0061] Comparative Example 1

[0062] The difference from Example 1 is only that the sample is a butene homopolymer (molecular weight 1.39×10 6 , molecular weight distribution 2.30). Figure 9 The crystal morphology of the butene homopolymer after isothermal crystallization at 80 °C is shown. It was found that in addition to forming spherulites with a Maltese cross extinction during isothermal crystallization of the butene homopolymer, it is impossible to form ring-banded spherulites. This shows that by changing the temperature and introducing a pentene copolymer unit, the polymer crystal morphology can be changed to form ring-banded spherulites.

[0063] Under the conditions of different isothermal crystallization temperatures and pentene copolymer unit contents in the above examples, the crystal morphologies of the butene / pentene copolymer are significantly different, indicating that the crystallization temperature and pentene copolymer unit content have a greater impact on the crystal morphology, and the crystal morphology is closely related to its crystal form. At the same time, obtaining ring-banded spherulites due to the cooperative torsion of lamellae along the radial direction of the spherulite provides a feasible method for the regulation of the crystal morphology and crystal form transformation of existing butene-based polymers.

[0064] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for regulating the crystal morphology of butene / pentene copolymer, characterized in that It includes the following steps: Heat the butene / pentene copolymer to 180 °C and hold for 10 min, then cool to the isothermal crystallization temperature and hold until complete crystallization, thus realizing the regulation of the crystal morphology of the butene / pentene copolymer.

2. The method for regulating the crystal morphology of the butene / pentene copolymer according to claim 1, wherein The content of the pentene copolymerization unit in the butene / pentene copolymer is 4.0 - 36.1 mol%.

3. The method for regulating the crystal morphology of the butene / pentene copolymer according to claim 1, wherein The molecular weight of the butene / pentene copolymer is 1.0 - 1.8×10 6 , and the molecular weight distribution is 1.8 - 2.3; the proportion of mmmm isotactic pentads in the butene / pentene copolymer is between 94% and 97%.

4. The method for regulating the crystal morphology of the butene / pentene copolymer according to claim 1, wherein The heating rate is 10 °C / min.

5. The method for regulating the crystal morphology of the butene / pentene copolymer according to claim 1, wherein The cooling rate is 30 °C / min.

6. The method for regulating the crystal morphology of a butene / pentene copolymer according to claim 1, wherein The isothermal crystallization temperature is 32 - 90 °C.

7. A method for regulating the melting temperature of a butene / pentene copolymer, characterized in that, Regulate the melting temperature of the butene / pentene copolymer by using the method for regulating the crystal morphology of the butene / pentene copolymer according to any one of claims 1 - 6.

Images