CN117946478B - Toughened isotactic polypropylene composite material and preparation method thereof, method for improving the impact strength of isotactic polypropylene - Google Patents

Abstract

The invention discloses a toughened isotactic polypropylene composite material, a preparation method thereof and a method for improving the impact strength of isotactic polypropylene, and belongs to the field of high polymer materials. The toughened isotactic polypropylene composite material comprises isotactic polypropylene, a second monomer and N' N-dicyclohexyl terephthalamide, wherein the second monomer is nylon 11, nylon 1212 or thermoplastic polyurethane elastomer; when the second monomer is nylon 11 or nylon 1212, the raw materials are as follows: 70-97 parts of isotactic polypropylene, 3-30 parts of second monomer and 0.05-1 part of N' -N-dicyclohexyl terephthalamide. According to the invention, DCHT can form different self-assembly morphologies at different temperature concentrations, and the mechanical properties of the isotactic polypropylene blend can be regulated and controlled by changing the processing temperature and the concentration, so that the preparation requirements of isotactic polypropylene with different mechanical property materials are met.

Description

Toughened isotactic polypropylene composite material and preparation method thereof, method for improving the impact strength of isotactic polypropylene

Technical Field

The present application relates to a toughened isotactic polypropylene composite material and a preparation method thereof, and a method for improving the impact strength of isotactic polypropylene, and belongs to the field of polymer materials.

Background technique

Isotactic polypropylene has the advantages of excellent comprehensive mechanical properties, good electrical insulation, chemical corrosion resistance, etc., and is also inexpensive, and has been widely used in daily necessities, home appliances, automobiles, etc. However, the impact resistance of isotactic polypropylene is poor, which limits its application range. Therefore, the toughening of isotactic polypropylene has always been a key research topic at home and abroad.

For example, Chinese patent application CN201310193831.0 discloses a method for toughening isotactic polypropylene (iPP ) products using random polypropylene as an elastomer, the method comprising the following steps: melt-blending and extruding random polypropylene (aPP) and isotactic polypropylene (iPP ) pellets in a twin-screw extruder, wherein the content of random polypropylene in the blend is less than 30 wt %; and then drying and injection molding the aPP/ iPP blend pellets on a common injection molding machine to form products.

Chinese patent application CN201910933449.6 discloses a toughened isotactic polypropylene composite material and a preparation method thereof. The composite filler prepared in this scheme is to melt-blend and modify isotactic polypropylene by surface-coated _SiO2 titanate whiskers and multi-walled carbon nanotube composite fillers. The impact strength of the obtained composite material is greatly improved. At the same time, the tensile strength is almost unaffected while the Young's modulus of the material is also improved.

Chinese patent application CN201510000542.3 discloses a method for preparing an in-situ toughened polypropylene alloy, in which high-vinyl polybutadiene is in-situ grafted onto a polypropylene molecular chain by a reactive extrusion method to improve the interfacial compatibility between polypropylene and high-vinyl polybutadiene.

At present, the main way to toughen isotactic polypropylene is to introduce rubber, elastomer or semi-crystalline polymer, such as EPDM rubber, EPDM rubber, high-density polyethylene, etc. Due to their poor compatibility, polypropylene grafted with maleic anhydride is often required as a compatibilizer.

Therefore, a new method and/or material is urgently needed to solve the above problems.

Summary of the invention

The invention object of the present application is to provide a toughened isotactic polypropylene composite material and a preparation method thereof, and a method for improving the impact strength of isotactic polypropylene, so as to achieve the toughening effect of isotactic polypropylene.

The technical solution of the present invention:

The first technical problem to be solved by the present invention is to provide a toughened isotactic polypropylene composite material, the raw materials of which include isotactic polypropylene, a second monomer and N'N-dicyclohexyl terephthalamide, wherein the second monomer is nylon 11, nylon 1212 or a thermoplastic polyurethane elastomer;

When the second monomer is nylon 11 or nylon 1212, the ratio of each raw material is:

Isotactic polypropylene 70-97 parts by weight,

3 to 30 parts by weight of the second monomer,

N'N-dicyclohexylterephthalamide 0.05-1 parts by weight;

When the second monomer is a thermoplastic polyurethane elastomer, the ratio of each raw material is:

Isotactic polypropylene 80 parts by weight,

The second monomer: 20 parts by weight,

N'N-dicyclohexylterephthalamide 0.05 to 1 parts by weight.

When the second monomer is nylon 11 or nylon 1212, the ratio of each raw material is:

Isotactic polypropylene 80 parts by weight,

The second monomer: 20 parts by weight,

N'N-dicyclohexylterephthalamide 0.05 to 1 parts by weight.

The composite material has a core-shell structure.

Furthermore, the second technical problem to be solved by the present invention is to provide a method for preparing the aforementioned toughened isotactic polypropylene composite material, the preparation method comprising: uniformly mixing isotactic polypropylene and a second monomer in proportion, adding N'N-dicyclohexylterephthalamide, and melt blending to obtain a first melt; then cooling and pelletizing the obtained first melt, and hot pressing and molding to obtain a toughened isotactic polypropylene composite material.

Further, melt blending is performed at a temperature of 180° C.-200° C., a time of 6-30 min, and a rotation speed of 30-60 rpm to obtain a first melt.

Furthermore, melt blending was performed at a temperature of 180° C., a time of 10 min, and a rotation speed of 50 rpm.

Furthermore, the hot pressing molding temperature is 200°C to 240°C.

The third technical problem to be solved by the present invention is to provide a method for improving the impact strength of isotactic polypropylene, the method comprising introducing N'N-dicyclohexyl terephthalamide and a second monomer into isotactic polypropylene, wherein the second monomer is selected from nylon 11 or nylon 1212 or a thermoplastic polyurethane elastomer;

When the second monomer is nylon 11 or nylon 1212, the ratio of each raw material is:

Isotactic polypropylene 70-97 parts by weight,

3 to 30 parts by weight of the second monomer,

N'N-dicyclohexylterephthalamide 0.05-1 parts by weight;

When the second monomer is a thermoplastic polyurethane elastomer, the ratio of each raw material is:

Isotactic polypropylene 80 parts by weight,

The second monomer: 20 parts by weight,

N'N-dicyclohexylterephthalamide 0.05 to 1 parts by weight.

The impact strength of isotactic polypropylene is improved by a method comprising the following steps: isotactic polypropylene and a second monomer are uniformly mixed according to a proportion, N'N-dicyclohexyl terephthalamide is added, and melt blending is performed to obtain a first melt; the first melt is then cooled, pelletized, and hot-pressed to obtain a toughened isotactic polypropylene composite material.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an electron microscope image of the impact fracture of the iPP /20%PA11 blend system in Example 1: from left to right, they correspond to 0.1% DCHT content at 240°C, 1.0% DCHT content at 200°C, and 0.3% DCHT content at 240°C.

Figure 2 is an electron microscope image of different DCHT concentrations and different temperatures in the iPP /20%PA11 blend system in Example 1: the first row corresponds from left to right to 0.05% DCHT content at 200°C, 0.1% DCHT content at 200°C, 0.3% DCHT content at 200°C, 0.5% DCHT content at 200°C, and 1% DCHT content at 200°C; the second row corresponds from left to right to 0.05% DCHT content at 240°C, 0.1% DCHT content at 240°C, 0.3% DCHT content at 240°C, 0.5% DCHT content at 240°C, and 1% DCHT content at 240°C.

Figure 3 is a diagram of the mechanical properties of the i PP/20% PA11 composite material prepared in Example 1: the left figure shows the tensile strength of i PP/20% PA11 at different DCHT contents and processing temperatures, and the right figure shows the impact strength of i PP/20% PA11 at different DCHT contents and processing temperatures.

Figure 4 is an electron microscope image of the i PP/0.3%DCHT blend system with different PA11 contents in Example 2: the first row corresponds from left to right to 3% PA11 content at 200°C, 10% PA11 content at 200°C, 15% PA11 content at 200°C, 20% PA11 content at 200°C, and 30% PA11 content at 200°C; the second row corresponds from left to right to 3% PA11 content at 240°C, 10% PA11 content at 240°C, 15% PA11 content at 240°C, 20% PA11 content at 240°C, and 30% PA11 content at 240°C.

Figure 5 is a diagram of the mechanical properties of the i PP/0.3%DCHT blend system with different PA11 contents in Example 2: the left figure shows the tensile strength of i PP/0.3%DCHT at different PA11 contents and processing temperatures, and the right figure shows the impact strength of i PP/0.3%DCHT at different PA11 contents and processing temperatures.

FIG . 6 is a diagram of the embodiment 3. Electron microscope images of different DCHT concentrations and temperatures in the PP/20%TPU372X blend system: the first row corresponds from left to right to 0.05% DCHT content at 200°C, 0.1% DCHT content at 200°C, 0.3% DCHT content at 200°C, 0.5% DCHT content at 200°C, and 1% DCHT content at 200°C; the second row corresponds from left to right to 0.05% DCHT content at 220°C, 0.1% DCHT content at 220°C, 0.3% DCHT content at 220°C, 0.5% DCHT content at 220°C, and 1% DCHT content at 220°C; the third row corresponds from left to right to 0.05% DCHT content at 240°C, 0.1% DCHT content at 240°C, 0.3% DCHT content at 240°C, 0.5% DCHT content at 240°C, and 1% DCHT content at 240°C.

Figure 7 is a diagram of the mechanical properties of the i PP/20% TPU372X blend system in Example 3: the left figure shows the tensile strength of i PP/20% TPU372X at different DCHT contents and processing temperatures, and the right figure shows the impact strength of i PP/20% TPU372X at different DCHT contents and processing temperatures.

Figure 8 is a diagram of the mechanical properties of the i PP/10%TPU372X/10%TPU1135AU blend system in Example 4: the left figure shows the tensile strength of i PP/10%TPU372X/10%TPU1135AU at different DCHT contents and processing temperatures, and the right figure shows the impact strength of i PP/10%TPU372X/10%TPU1135AU at different DCHT contents and processing temperatures.

Figure 9 shows the DSC spectra of Comparative Example 4, Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 6, and Example 5: the first row corresponds from left to right to i PP/0.05%DCHT, i PP/3%PA6/0.05%DCHT, i PP/3%PA610/0.05%DCHT, and the second row corresponds from left to right to i PP/3%PA612/0.05%DCHT, i PP/3%PA11/0.05%DCHT, i PP/3%PA1212/0.05%DCHT.

Figure 10 shows polarizing microscope images of Comparative Example 4, Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 6, and Example 5: from top to bottom, they correspond to i PP/0.05%DCHT, i PP/3%PA6/0.05%DCHT, i PP/3%PA610/0.05%DCHT, i PP/3%PA612/0.05%DCHT, i PP/3%PA11/0.05%DCHT, and i PP/3%PA1212/0.05%DCHT.

FIG11 shows the rheological diagrams of Example 6 and Comparative Example 4.

Detailed ways

In view of the problem of toughening isotactic polypropylene, the present application provides a toughened isotactic polypropylene composite material and a preparation method thereof. More specifically, the present application provides a toughened isotactic polypropylene composite material and a preparation method thereof. In the formula of the present application, DCHT is both a nucleating agent for isotactic polypropylene and can induce isotactic polypropylene to form β crystals. At the same time, the amide bonds on DCHT can form hydrogen bonds with PA11 (or PA1212) and TPU, which can play a role in volume expansion. Furthermore, in the composite material prepared by the present application, PA11 (or PA1212) or TPU is used as the core, DCHT is adsorbed on the surface of PA11 (or PA1212) or TPU, and DCHT induces isotactic polypropylene to crystallize. DCHT and partially crystallized isotactic polypropylene form an outer shell, thereby forming a toughened isotactic polypropylene composite material with a core-shell structure. The experimental results show that the present application can improve the toughness of isotactic polypropylene blends. Furthermore, in the present application, DCHT will form different self-assembly morphologies at different temperature concentrations. By changing the processing temperature and concentration, the mechanical properties of the isotactic polypropylene blend can be regulated, thereby meeting the preparation requirements of isotactic polypropylene with different mechanical properties.

All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and/or steps, can be combined in any manner.

Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

Example 1

Table 1 Mass ratio of each component in Example 1

Serial number Isotactic polypropylene ( iPP , grade T30S)/kg Nylon 11 (PA11, brand BESN P40)/kg N'N-dicyclohexylterephthalamide (DCHT)/kg DCHT content (%) 01 80 20 0.05 0.05 02 80 20 0.1 0.1 03 80 20 0.3 0.3 04 80 20 0.5 0.5 05 80 20 1.0 1.0

In Table 1, the calculation formula for DCHT content (%) is as follows:

The mass of DCHT/(the mass of iPP +the mass of nylon 11)=DCHT content (%).

The preparation method of the toughened isotactic polypropylene composite material of this embodiment is as follows:

(1) Weigh each component according to the weight ratio in Table 1 and set aside;

(2) The weighed isotactic polypropylene and nylon 11 are mixed uniformly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time, and melt blending is performed at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt, and then the obtained melt is cooled and pelletized;

(3) The obtained pellets are hot-pressed at 200°C and 240°C using a flat plate vulcanizer.

Figure 1 shows the electron microscope image of the impact fracture of the iPP /20%PA11 blend system in this embodiment. In Figure 1, from left to right, it corresponds to 0.1% DCHT content at 240°C, 1.0% DCHT content at 200°C, and 0.3% DCHT content at 240°C; the DCHT content corresponds to the DCHT content in Table 1, and 200°C and 240°C correspond to the hot pressing molding temperatures.

From the left side of Figure 1, the first and second pictures show an obvious core-shell structure. The white part of the broken sphere is the core PA11, and the gray part on the surface is the shell DCHT and isotactic polypropylene crystals. From the left side of Figure 1, the third picture shows that there are white snowflake-shaped polypropylene residues in the hemispherical pit on the impact section, indicating that the core-shell structure sphere is tightly combined with the polypropylene matrix.

Figure 2 shows the electron microscope images of the blending system of different PA11 contents under i PP/0.3%DCHT in this embodiment. In Figure 2, the first column corresponds from left to right to 0.05% DHCT content at 200°C, 0.1% DHCT content at 200°C, 0.3% DHCT content at 200°C, 0.5% DHCT content at 200°C, and 1% DHCT content at 200°C, and the second column corresponds from left to right to 0.05% DHCT content at 240°C, 0.1% DHCT content at 240°C, 0.3% DHCT content at 240°C, 0.5% DHCT content at 240°C, and 1% DHCT content at 240°C.

As can be seen from Figure 2, at higher DCHT content (0.5%, 1%), the DCHT on the surface of the sphere is mainly rod-shaped crystals, and at lower DCHT content (0.05%, 0.1%), the DCHT on the surface of the sphere is patterned crystals. 0.3% DCHT is quite special. At 200°C, rod-shaped and patterned crystals coexist. When the temperature rises to 240°C, the DCHT crystals melt and assemble into patterned shapes. Figure 2 Conclusion: Different hot pressing temperatures will change the crystal morphology of DCHT. Patterned crystals have better capacity expansion effect because their crystals are finer and cover the PA11 surface evenly.

The mechanical properties of the toughened isotactic polypropylene composite prepared in this example are shown in Figure 3. As can be seen from Figure 3, the tensile strength decreases with the increase of DCHT concentration, and the Izod notched impact strength increases first and then decreases with the increase of DCHT concentration. When the DCHT content is 0.5% and 240%, it can best reach 10.1 kJ/ ^m2 , and the tensile strength can also be maintained at 25.9 MPa. It can be found that at higher DCHT concentrations (0.3, 0.5, 1), the Izod notched impact strength of the 240℃ sample is greater than that of 200℃. This is because at higher temperatures, the DCHT crystals are finer after melting and reorganization (as shown in the electron microscope in Figure 2), and the compatibilization effect on PA11 and i PP is better.

Example 2

Table 2 Mass ratio of each component in Example 2

Serial number Isotactic polypropylene ( iPP , grade T30S)/kg Nylon 11 (PA11, brand BESN P40)/kg N'N-dicyclohexyl terephthalamide (DCHT)/kg PA11 content (%) 06 97 3 0.3 3 07 90 10 0.3 10 08 85 15 0.3 15 09 80 20 0.3 20 10 70 30 0.3 30

In Table 2, in this embodiment, the sum of the masses of isotactic polypropylene and PA11 is 100 kg, and the calculation formula of the PA11 content (%) is as follows:

Mass of PA11/100kg=PA11 content (%).

The preparation method of the toughened isotactic polypropylene composite material of this embodiment is as follows:

(1) Weigh each component according to the weight ratio in Table 2 and set aside;

(2) The weighed isotactic polypropylene and nylon 11 are mixed uniformly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time, and melt blending is performed at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt, and then the obtained melt is cooled and pelletized;

(3) The obtained pellets are hot-pressed at 200°C and 240°C using a flat plate vulcanizer.

Figure 4 shows the electron microscope images of the blending system with different PA11 contents under i PP/0.3%DCHT in this embodiment. In Figure 4, the first column corresponds from left to right to 3% PA11 content at 200°C, 10% PA11 content at 200°C, 15% PA11 content at 200°C, 20% PA11 content at 200°C, and 30% PA11 content at 200°C, and the second column corresponds from left to right to 3% PA11 content at 240°C, 10% PA11 content at 240°C, 15% PA11 content at 240°C, 20% PA11 content at 240°C, and 30% PA11 content at 240°C; wherein the PA11 content corresponds to the PA11 content in Table 1, and 200°C and 240°C correspond to the hot pressing molding temperatures.

As can be seen from Figure 4, with the increase of PA11 content, the size of PA11 spheres increases and becomes more uneven. It can be clearly seen on larger spheres that DCHT crystals wrap the entire PA11 sphere. At the same time, DCHT crystals coexist in rod-shaped and pattern-shaped crystals at 200°C. When the temperature rises to 240°C, they melt and assemble into pattern-shaped crystals.

The mechanical properties of the toughened isotactic polypropylene composite material prepared in this example are shown in FIG5 . As can be seen from FIG5 , as the PA11 content increases, the tensile strength of the system decreases, and the Izod notched impact strength increases first and then decreases. The Izod notched impact strength of the sample at 240°C under 10% PA11 is preferably 10.3 kJ/m ² , and the tensile strength can be maintained at 28.5 MPa. At the same time, the Izod notched impact strength of the sample at 240°C is higher than that at 200°C, which is consistent with the reason in FIG3 , because the DCHT crystals are finer at higher temperatures, making them more compatible.

Example 3

Table 3 Mass ratio of each component in Example 3

Serial number Isotactic polypropylene ( iPP , grade T30S)/kg Thermoplastic polyurethane elastomer (TPU, grade 372X)/kg N'N-dicyclohexyl terephthalamide (DCHT)/kg DCHT content (%) 11 80 20 0.05 0.05 12 80 20 0.1 0.1 13 80 20 0.3 0.3 14 80 20 0.5 0.5 15 80 20 1.0 1.0

In Table 3, the calculation formula for DCHT content (%) is as follows:

The mass of DCHT/(the mass of iPP +the mass of TPU)=DCHT content (%).

The preparation method of the toughened isotactic polypropylene composite material of this embodiment is as follows:

(1) Weigh each component according to the weight ratio in Table 3 and set aside;

(2) The weighed isotactic polypropylene and TPU are mixed evenly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time, and melt blending is performed at a temperature of 190°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt, and then the obtained melt is cooled and pelletized;

(3) The obtained pellets are hot-pressed at 200°C, 220°C, and 240°C using a flat plate vulcanizer.

FIG. 6 shows electron micrographs of the i PP/20% TPU372X blend system at different DCHT concentrations and different temperatures in this embodiment. In Figure 6, the first column corresponds from left to right to 0.05% DCHT content at 200°C, 0.1% DCHT content at 200°C, 0.3% DCHT content at 200°C, 0.5% DCHT content at 200°C, and 1.0% DCHT content at 200°C. The second column corresponds from left to right to 0.05% DCHT content at 220°C, 0.1% DCHT content at 220°C, 0.3% DCHT content at 220°C, 0.5% DCHT content at 220°C, and 1.0% DCHT content at 220°C. The third column corresponds from left to right to 0.05% DCHT content at 240°C, 0.1% DCHT content at 240°C, 0.3% DCHT content at 240°C, 0.5% DCHT content at 240°C, and 1.0% DCHT content at 240°C. In Figure 6, the same 8μm scale is used.

As can be seen from Figure 6, when the hot pressing molding temperature is 200°C and 220°C, DCHT is mainly rod-shaped crystals; when the hot pressing molding temperature is 240°C, 0.05%, 0.1%, and 0.3% DCHT are fine patterned crystals; when the hot pressing molding temperature is 240°C, 0.5% and 1% DCHT are rod-shaped crystals; this is because the complete melting temperature of the nucleating agent DCHT increases with the increase of its content, and the incompletely melted DCHT will form rod-shaped crystals.

The mechanical properties of the toughened isotactic polypropylene composite prepared in this example are shown in Figure 7. As can be seen from Figure 7, similar to the iPP /PA11 system, the tensile strength decreases with the increase of DCHT concentration, and the Izod notched impact strength increases first and then decreases with the increase of DCHT concentration. However, after adding TPU, the mechanical properties are more significantly improved, and the best value can reach 12.5kJ/ ^m2 at 0.5% DCHT content at 240℃, and the tensile strength can also be maintained at 26.6MPa.

Example 4

Table 4 Mass ratio of each component in Example 4

Serial number Isotactic polypropylene ( iPP , grade T30S)/kg Thermoplastic polyurethane elastomer (TPU, grade 372X)/kg Thermoplastic polyurethane elastomer (TPU, grade 1135AU)/kg N'N-dicyclohexyl terephthalamide (DCHT)/kg DCHT content (%) 16 80 10 10 0.05 0.05 17 80 10 10 0.1 0.1 18 80 10 10 0.3 0.3 19 80 10 10 0.5 0.5 20 80 10 10 1.0 1.0

In Table 4, the calculation formula for DCHT content (%) is as follows:

The mass of DCHT/(the mass of iPP +the mass of TPU)=DCHT content (%).

The preparation method of the toughened isotactic polypropylene composite material of this embodiment is as follows:

(1) Weigh each component according to the weight ratio in Table 3 and set aside;

(2) The weighed isotactic polypropylene and TPU are mixed evenly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time, and melt blending is performed at a temperature of 190°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt, and then the obtained melt is cooled and pelletized;

(3) The obtained pellets are hot-pressed at 200°C and 240°C using a flat plate vulcanizer.

The mechanical properties of the toughened isotactic polypropylene composite material prepared in this example are shown in Figure 8. As can be seen from Figure 8, the introduction of softer TPU1135AU to form a core-shell structure with a soft core and a hard shell can greatly improve the toughness of the i PP system, among which 0.1%DCHT has the best performance at 240°C, with an Izod notched impact strength of up to 18.5 kJ/m ² and a tensile strength of 24.9 MPa.

Comparative Example 1

In this example, the preparation method of the composite material is as follows.

(1) Weigh the following components according to the following mass ratio: 97 kg isotactic polypropylene ( iPP , brand T30S), 3 kg nylon 6 (PA6, brand 73G30L NC010), 0.05 kg N', N'-dicyclohexyl terephthalamide (DCHT), and set aside.

(2) The weighed isotactic polypropylene and nylon 6 are mixed evenly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time. The mixture is melt-blended at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt. The obtained melt is then cooled and pelletized.

(3) The obtained pellets are hot-pressed at 200°C using a flat plate vulcanizer.

Comparative Example 2

In this example, the preparation method of the composite material is as follows.

(1) Weigh the following components according to the following mass ratio: 97 kg isotactic polypropylene ( iPP , brand T30S), 3 kg nylon 610 (PA610, brand RS32617L NC010), and 0.05 kg N',N'-dicyclohexylterephthalamide (DCHT) for later use.

(2) The weighed isotactic polypropylene and nylon 610 are mixed evenly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time. The mixture is melt-blended at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt. The obtained melt is then cooled and pelletized.

(3) The obtained pellets are hot-pressed at 200°C using a flat plate vulcanizer.

Comparative Example 3

In this example, the preparation method of the composite material is as follows.

(1) Weigh the following components according to the following mass ratio: 97 kg isotactic polypropylene ( iPP , brand T30S), 3 kg nylon 612 (PA612, brand 151L NC010), and 0.05 kg N',N'-dicyclohexylterephthalamide (DCHT) for later use.

(2) The weighed isotactic polypropylene and nylon 612 are mixed evenly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time. The mixture is melt-blended at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt. The obtained melt is then cooled and pelletized.

(3) The obtained pellets are hot-pressed at 200°C using a flat plate vulcanizer.

Example 5

In this example, the preparation method of the composite material is as follows.

(1) Weigh the following components according to the following mass ratio: 97 kg isotactic polypropylene ( iPP , brand T30S), 3 kg nylon 1212 (PA1212, brand 3300), 0.05 kg N',N'-dicyclohexylterephthalamide (DCHT) and set aside.

(2) The weighed isotactic polypropylene and nylon 1212 are mixed evenly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time. The mixture is melt-blended at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt. The obtained melt is then cooled and pelletized.

(3) The obtained pellets are hot-pressed at 200°C using a flat plate vulcanizer.

Comparative Example 4

In this example, the preparation method of the composite material is as follows.

(1) Weigh the components according to the following mass ratio: 100 kg isotactic polypropylene ( iPP , brand T30S), 0.05 kg N', N'-dicyclohexyl terephthalamide (DCHT), and set aside.

(2) The weighed isotactic polypropylene is added into an internal mixer, and N'N-dicyclohexylterephthalamide is added at the same time, and melt blending is carried out at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt, and then the obtained melt is cooled and pelletized.

(3) The obtained pellets are hot-pressed at 200°C using a flat plate vulcanizer.

Example 6

In this example, the preparation method of the composite material is as follows.

(1) Weigh the following components according to the following mass ratio: 97 kg isotactic polypropylene ( iPP , brand T30S), 3 kg nylon 11 (PA11, brand BESN P40), 0.05 kg N',N'-dicyclohexyl terephthalamide (DCHT) and set aside.

(2) The weighed isotactic polypropylene and nylon 11 are mixed evenly, added into an internal mixer, and N'N-dicyclohexyl terephthalamide is added at the same time. The mixture is melt-blended at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm to obtain a melt. The obtained melt is then cooled and pelletized.

(3) The obtained pellets are hot-pressed at 200°C using a flat plate vulcanizer.

In Figure 9, in order from left to right and from top to bottom, the six pictures correspond to the DSC spectrum of Comparative Example 4, the DSC spectrum of Comparative Example 1, the DSC spectrum of Comparative Example 2, the DSC spectrum of Comparative Example 3, the DSC spectrum of Example 6, and the DSC spectrum of Example 5, respectively.

As can be seen from the DSC diagram in Figure 9, only the system with PA11 and PA1212 has a significant decrease in crystallization temperature at high temperature, indicating that DCHT does not play a nucleation role at this time. This is because DCHT and PA11 (or PA1212) have strong hydrogen bond interactions, and the DCHT content is low, so it can be completely dissociated at high temperatures; when the temperature drops, the free DCHT molecules will be attracted by PA11, delaying their own self-assembly process, and they have not completed self-assembly when i PP crystallizes, and cannot play a nucleation role. PA1212 is similar to PA11 in that it has an attraction to DCHT. DCHT may also have a capacity-enhancing effect on PA1212 and iPP, and can form a core-shell structure. The other three PAs are similar to pure i PP with only DCHT added at high temperatures, and the crystallization temperature does not change much, indicating that the adsorption effect on DCHT is not good, and it cannot play a good capacity-enhancing role in the system later, and the core-shell structure may not be formed.

In FIG10 , from top to bottom are polarizing microscope images of Comparative Example 4, polarizing microscope images of Comparative Example 1, polarizing microscope images of Comparative Example 2, polarizing microscope images of Comparative Example 3, polarizing microscope images of Example 6, and polarizing microscope images of Example 5, and from left to right, they correspond to polarizing microscope images at different times. In FIG10 , from left to right, the corresponding observation times are 0s, 60s, 300s, and 600s.

The test conditions of Figure 10 are as follows: the temperature was raised to 280°C under a polarizing microscope, and then cooled to 130°C at a rate of 10°C/min, and isothermal crystallization was performed for 10 minutes. As can be seen from Figure 10, the crystallization rates of the PA11 and PA1212 systems are significantly lower, and the final crystal size is smaller, which is consistent with the DCS results, indicating that DCHT does not play a nucleation role.

As can be seen from Figure 11, the complex viscosity of the i PP/0.05DCHT system (i.e., the composite material prepared in Comparative Example 4) of DCHT self-assembled normally in i PP has an ascending step at about 150°C, indicating that the DCHT self-assembly is completed at this time, and the DCHT crystal increases the complex viscosity of the melt at this temperature; while i PP/3PA11/0.05DCHT (i.e., the composite material prepared in Example 6) does not have this step, indicating that the self-assembly is delayed. The warping of the curve in the low temperature end region is due to the crystallization of i PP. The warping temperature of the i PP/3PA11/0.05DCHT system is lower, and its crystallization temperature is lower, which is consistent with the results of DSC and POM (i.e., polarizing microscope test results).

The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims (8)

1. A toughened isotactic polypropylene composite material, characterized in that its raw materials include isotactic polypropylene, a second monomer and N'N-dicyclohexyl terephthalamide, and the second monomer is nylon 11 or a thermoplastic polyurethane elastomer; When the second monomer is nylon 11, the ratio of each raw material is: Isotactic polypropylene 70-90 parts by weight, The second monomer 10 to 30 parts by weight, N'N-dicyclohexylterephthalamide 0.05-1 parts by weight; When the second monomer is a thermoplastic polyurethane elastomer, the ratio of each raw material is: Isotactic polypropylene 80 parts by weight, The second monomer: 20 parts by weight, N'N-dicyclohexylterephthalamide 0.05-1 parts by weight; Furthermore, the composite material has a core-shell structure. 2. The toughened isotactic polypropylene composite material according to claim 1, characterized in that when the second monomer is nylon 11, the ratio of each raw material is: Isotactic polypropylene 80 parts by weight, The second monomer: 20 parts by weight, N'N-dicyclohexylterephthalamide 0.05 to 1 parts by weight. 3. The method for preparing the toughened isotactic polypropylene composite material according to claim 1 or 2, characterized in that the preparation method comprises: uniformly mixing isotactic polypropylene and a second monomer in proportion, adding N'N-dicyclohexylterephthalamide, and melt blending to obtain a first melt; then cooling and pelletizing the obtained first melt, and hot pressing to obtain the toughened isotactic polypropylene composite material. 4. The preparation method according to claim 3 is characterized in that melt blending is carried out at a temperature of 180°C to 200°C, a time of 6 to 30 min, and a rotation speed of 30 to 60 rpm to obtain the first melt. 5. The preparation method according to claim 4 is characterized in that melt blending is carried out at a temperature of 180°C, a time of 10 min, and a rotation speed of 50 rpm. 6. The preparation method according to claim 3, characterized in that the hot pressing molding temperature is 200°C to 240°C. 7. A method for improving the impact strength of isotactic polypropylene, characterized in that the method comprises introducing N'N-dicyclohexyl terephthalamide and a second monomer into isotactic polypropylene, wherein the second monomer is selected from nylon 11 or thermoplastic polyurethane elastomer; When the second monomer is nylon 11, the ratio of each raw material is: Isotactic polypropylene 70-90 parts by weight, The second monomer 10 to 30 parts by weight, N'N-dicyclohexylterephthalamide 0.05-1 parts by weight; When the second monomer is a thermoplastic polyurethane elastomer, the ratio of each raw material is: Isotactic polypropylene 80 parts by weight, The second monomer: 20 parts by weight, N'N-dicyclohexylterephthalamide 0.05-1 parts by weight; Furthermore, the obtained composite material has a core-shell structure. 8. The method according to claim 7, characterized in that the impact strength of isotactic polypropylene is improved by a method comprising the following steps: after uniformly mixing isotactic polypropylene and a second monomer in proportion, adding N'N-dicyclohexylterephthalamide, and melt blending to obtain a first melt; then cooling and pelletizing the obtained first melt, and hot pressing to obtain a toughened isotactic polypropylene composite material.