32results about How to "Improve melt strength" patented technology

The invention discloses a polyhydroxyalkanoate composition and a preparation method thereof. The polyhydroxyalkanoate composition comprises the following components in parts by mass: 100 parts of polyhydroxyalkanoate; 0.5 to 5 parts of unsaturated D-polylactic acid; 0.5 to 5 parts of poly (L-lactic acid); the preparation method comprises the following steps: S1, carrying out melt blending on the polyhydroxyalkanoate and the unsaturated D-polylactic acid, and enabling the polyhydroxyalkanoate and the unsaturated D-polylactic acid to fully react, so as to obtain an intermediate product; and S2, carrying out melt blending on the intermediate product obtained in the step S1, poly-L-lactic acid and an ester exchange inhibitor to finally obtain the polyhydroxyalkanoate composition with excellent thermal stability, high melt strength and high crystallization speed.

The invention relates to the technical field of polymer composite material preparation, in particular to a super-tough core-shell stereocomplex polylactic acid-based composite material and a preparation method thereof. The super-tough core-shell stereocomplex polylactic acid-based composite material is prepared from the following raw materials in parts by mass: 70 to 100 parts of polylactic acid and 0 to 30 parts of the modified elastomer in claim 4, and the dosage of the modified elastomer is not 0; the modified elastomer is prepared by melting and blending stereocomplex polylactic acid powder and a functional elastomer copolymer; the stereocomplex polylactic acid powder is prepared by reactive melt blending of PLLA and PDLA in an equal mass ratio or an equal molar ratio. The prepared super-tough core-shell stereocomplex polylactic acid-based composite material has excellent tensile strength and impact resistance, can be applied to the field of engineering plastics such as automobile parts, electronic and electric appliance shells, household products, catering tableware and the like, and has remarkable environmental protection benefits and industrial popularization value.

This invention discloses a method for preparing low-density, high-filler SPC flooring. The method is characterized by a raw material formulation comprising the following components in the indicated weight proportions: 100 parts graft-modified PVC resin, 300-350 parts filler, 9-12 parts heat stabilizer, 3-5 parts melt processing modifier, 3-5 parts reinforcing and toughening modifier, 1-2 parts external lubricant, 1-2 parts internal lubricant, 2-5 parts chemical foaming agent, and 2-5 parts foaming aid. The graft-modified PVC resin is prepared by replacing the chlorine atoms in PVC with p-aminothiophenol, followed by an amidation reaction between a diacid or polyacid and an amino group. Its advantages are: 1) It improves the melt strength and expandability of the PVC resin, ensuring foaming performance under high filler content. Compared with ordinary SPC flooring, the flooring product has lower density and lighter weight, higher hardness, and lower overall formulation cost compared to ordinary low-density SPC flooring. 2) The process is simple, and the product has high controllability.

This invention relates to the field of polymer foaming materials technology, and discloses a plant fiber composite nucleating agent for microfoaming of biodegradable materials and its application. The plant fiber composite nucleating agent is made from raw materials comprising the following parts by weight: 80-95 parts of primary ultrafine plant fiber powder, 5-20 parts of surface modifier, and 0.1-5 parts of dispersing lubricating wax; the surface modifier and dispersing lubricating wax are coated on the surface of the primary ultrafine plant fiber powder. The application steps are as follows: adding the plant fiber composite nucleating agent to a biodegradable material matrix to obtain a pre-foaming blend, introducing foaming gas or adding a chemical foaming agent for foaming treatment. The nucleating agent of this invention improves the compatibility between plant fibers and hydrophobic biodegradable matrices, provides heterogeneous nucleation sites in the matrix while increasing the polymer melt strength, inhibits cell coalescence and rupture, and obtains microfoamed materials with uniform pore size. Furthermore, the nucleating agent itself is completely biodegradable.

The invention provides an environment-friendly high polymer material additive as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials, the preparation method comprises the following steps: dissolving beta-cyclodextrin into an anhydrous solvent, adding methacryloyl chloride, controlling the molar ratio of methacryloyl chloride to beta-cyclodextrin to be 1: 1, carrying out substitution reaction, then adding excessive acetic anhydride, and carrying out heat preservation reaction to obtain the environment-friendly high polymer material additive. Carrying out acetylation reaction, and purifying to obtain modified beta-cyclodextrin; adding glycidyl methacrylate, ethylene and modified beta-cyclodextrin into a reaction kettle, and carrying out high-pressure free radical polymerization in the presence of an initiator and a chain transfer agent to obtain the environment-friendly high polymer material additive, wherein the mass ratio of the glycidyl methacrylate to the ethylene to the modified beta-cyclodextrin is (4-8): (88-94): (2-4). According to the prepared additive, the processing rheological property and mechanical toughness of a PCR material are improved, meanwhile, the release characteristic of low-volatility organic compounds is considered, and the application requirements of the fields of automobile interiors and high-end packaging are easily met.

The invention relates to a fluoride-free flame-retardant polyester reinforced resin composition as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The resin composition comprises the following components in parts by weight: 15-55 parts of PBT resin; 0 to 20 parts of PET resin; 10 to 50 parts of glass fiber; 10 to 15 parts of brominated aromatic flame retardant; 1-3 parts of a compatilizer; 1-5 parts of a toughening agent; 1.5 to 3.0 parts of an antimony flame retardant synergist; 2-5 parts of a high carbon residue charring agent; 0.2 to 0.5 part of an antioxidant; and 0.5 to 1.0 part of a lubricant. Compared with the prior art, the fluorine-free flame-retardant polyester reinforced resin prepared by the invention not only has excellent mechanical properties and good processability, but also has lower cost and wide application scenarios.

The application discloses a kind of polylactic acid double-stretching film materials and preparation method thereof, belong to the field of biaxially oriented film.The polylactic acid double-stretching film material includes the following mass fraction of raw materials: polylactic acid 95~99 parts, melt strength improvement aid 1~5 parts, hydrolysis inhibitor 0.3~1 parts and processing aid 0.5~1 parts;Melt strength improvement aid is ultra-high molecular weight polar polymer;Ultra-high molecular weight polar polymer contains one or a combination of two of epoxy group and side chain ester group.The melt strength improvement aid improves the melt strength and melt uniformity of polylactic acid, thereby improving the yield and film thickness uniformity of polylactic acid double-stretching film;The addition of hydrolysis inhibitor improves the heat processing stability of the material, to obtain a kind of processing performance excellent, while taking into account melt strength and uniformity, thickness fluctuation small polylactic acid double-stretching film material.

This invention discloses a method for preparing a modified chitosan whisker-reinforced and toughened PBAT microfoamed composite material. Biodegradable and high-modulus chitosan whiskers are selected as the reinforcing agent, enabling the composite material to achieve full biodegradability. Through surface modification technology, PBAT segments with the same composition as the PBAT matrix are introduced onto the surface of the chitosan whiskers. This design ensures good compatibility between the chitosan whiskers and the matrix, resulting in thorough dispersion within the matrix and achieving a more efficient reinforcement and toughening effect than traditional reinforcing agents. Simultaneously, the grafted and modified chitosan whiskers can increase the melt viscosity and melt strength of the PBAT matrix, thereby improving its foaming properties.

This invention relates to the field of propylene polymerization, and discloses a polypropylene, its preparation method, and its applications. The polypropylene has a molecular weight distribution of 6-20; at 230℃, a melt index of 0.1-10 g / 10 min with a loading of 2.16 kg; an isotactic index ≥97%; a fraction with a weight-average molecular weight M ≥ 5 million g / mol containing ≥1 wt%, a fraction with 1000 g / mol < M < 50000 g / mol containing 5-30 wt%, a fraction with 50000 g / mol ≤ M < 5 million g / mol containing 60-90 wt%, and a fraction with M ≤ 1000 g / mol containing <1 wt%; a melt strength ≥0.4 N at 230℃; a heat distortion temperature ≥95℃; and a flexural modulus ≥1800 MPa. This polypropylene exhibits high isotacticity, a wide molecular weight distribution, high flexural modulus, and also high melt strength and heat resistance.

This invention discloses a polyester material, a heat-shrinkable film, its preparation method, and its applications. The raw materials for preparing the polyester material include a diacid, a diol, a chain extender, a stabilizer, and a catalyst; wherein the diacid comprises: 90 mol%~95 mol% polyterephthalic acid and 5 mol%~10 mol% isophthalic acid; the diol comprises: 65 mol%~78 mol% ethylene glycol, 18 mol%~28 mol% 1,4-cyclohexanediol, and 4 mol%~12 mol% diethylene glycol; the chain extender is 2,2'-(1,3-phenylene)-dioxazoline, added in an amount of 0.2%~0.8% of the total mass of the diol and the diacid; the molar ratio of carboxyl groups to hydroxyl groups in the diacid and the diol is 1:1~1.05. The polyester material of this invention possesses excellent transparency, shrinkage rate, and strength, and has a low initial shrinkage temperature, making it particularly suitable for applications such as heat-shrinkable films. This invention also provides a heat-shrinkable film, as well as the polyester material, a method for preparing the heat-shrinkable film, and their applications.

The invention relates to the field of propylene polymerization, and discloses a preparation method of polypropylene, polypropylene and application. The method comprises the following steps: S1, in the presence of a functional external electron donor and a catalyst system, carrying out a prepolymerization reaction on propylene to obtain a prepolymer A; the prepolymerization multiplying power is 1000 to 10000 times; s2, in the presence of a first molecular weight regulator, a first external electron donor and the prepolymer A, performing a first polymerization reaction on propylene to obtain a polymer B; s3, in the presence of a second molecular weight regulator, a second external electron donor and a polymer B, carrying out propylene second polymerization reaction to obtain polypropylene. According to the method, the prepolymerization reaction is combined with the polymerization reaction of two stages, the functional external electron donor is introduced in the prepolymerization process, and the specific first external electron donor and the specific second external electron donor are subsequently matched, so that the prepared polypropylene has good processability and heat resistance.

This invention relates to the field of organic synthesis technology, and in particular to a monophosphine halide and its preparation method, as well as a method for preparing polypropylene resin. The monophosphine halide provided by this invention has the following structure: where n is an integer between 1 and 4, and X is selected from any one of F, Cl, Br, and I. The monophosphine halide of this invention has a specific structure, and when used in the polymerization reaction of propylene, the monophosphine halide polymerizes with propylene under the action of a catalyst to obtain a high melt strength polypropylene resin with a long-chain branched structure, thereby achieving a low-cost, high-performance reactor method for preparing polypropylene resin.

This invention relates to the field of preparation method technology and discloses a method for preparing a low-density nylon foam material. The method includes selecting nylon resin as the matrix material, wherein the nylon resin is a blend of PA6 and amorphous nylon PA610 in a specific ratio, wherein the mass ratio of PA6 to PA610 is 60:40 to 80:20, and the melt strength of the nylon resin is greater than or equal to 18 Pa·s; introducing a composite foaming agent, wherein the composite foaming agent is a combination of a chemical foaming agent and a physical foaming agent; and adding a nucleating agent, wherein the nucleating agent is nano-sized silica, nano-clay, talc, or a combination thereof, wherein the mass content of nano-silica is 0.5% to 2.0%. This invention can maintain stable dimensions and mechanical properties in humid environments and has a uniform and stable cell structure.

The invention provides environment-friendly grass silk for artificial turf and a preparation method thereof, and belongs to the technical field of artificial fibers.The environment-friendly grass silk is prepared from, by weight, 40-60 parts of polylactic acid, 4-8 parts of octavinyl-POSS, 12-18 parts of hyperbranched polymer and 2-5 parts of auxiliaries; the hyperbranched polymer comprises a hyperbranched polyester skeleton derived from epoxidized vegetable oil and an epoxy functional group connected to the tail end of the skeleton. The grass yarn material provided by the invention has excellent biodegradability and mechanical properties, the compatibility, melt strength and processability of a polylactic acid matrix are remarkably enhanced by introducing the hyperbranched polymer and octavinyl-POSS, and meanwhile, the octavinyl-POSS is used as a cross-linking agent to construct a three-dimensional network structure, so that the dimensional stability and durability are greatly improved, and the grass yarn material can be widely applied to the field of biological engineering. And the whole method has the advantages of obvious environmental friendliness and sustainability.

The invention relates to the technical field of polymer composite material processing, and discloses a blending extrusion preparation method of a plant fiber reinforced biodegradable foaming material, which comprises the following steps: firstly, preparing polycaprolactone glycol, zinc isoocatanoate and absolute ethyl alcohol into a polar cosolvent system; the plant fibers are deagglomerated by utilizing the permeation effect of the solvent and a hydrogen bond damage mechanism; then, in a first extruder, a melt sealing material is formed through base resin in a specific proportion to maintain the vacuum degree of a middle-section devolatilization area, and it is ensured that absolute ethyl alcohol is completely removed; in the rear section of the extruder, zinc isoocatanoate immobilized on the surface of the fiber is utilized to catalyze the polyfunctional group epoxy chain extender to generate in-situ ring opening grafting, and a flexible transition layer is constructed on the interface of the fiber and the resin. The problems that plant fibers are prone to agglomeration and poor in resin interface bonding force are solved, the melt strength of a composite system is improved, and the prepared foaming material is uniform in foam hole and stable in performance and has good industrial application prospects.

The application discloses a high-enthalpy flexible phase change material and a preparation method and application thereof, and relates to the technical field of high polymer composite materials.The preparation method comprises the following steps: taking maleic anhydride as a grafting agent, and polyolefin thermoplastic elastomer as a grafting object to prepare a grafting modified thermoplastic elastomer; adding a crosslinking agent and a phase change material into the grafting modified thermoplastic elastomer, and melt blending to obtain the high-enthalpy flexible phase change material.The preparation method has the following advantages: more excellent flexibility, the three-dimensional crosslinking network is constructed through the introduction of anhydride-ester dynamic bond, and the organic solid-liquid phase change material is reinforced and toughened; high energy storage density; the introduction of the crosslinking network enables the polymer support structure to better coat the phase change material, and the content of the phase change material is ensured, that is, the high energy storage density is provided.

This invention relates to the fields of polymer material synthesis technology and formulation modification technology, specifically to a narrow-distribution high-strength polyethylene and its preparation method. The invention discloses a narrow-distribution high-strength polyethylene and its preparation method, wherein the polyethylene molecular chain has long-chain branched structures grafted onto it, and the molecular weight distribution exhibits a narrow distribution characteristic. This polyethylene is prepared by a two-reactor series process, wherein the first reactor generates macromonomers containing terminal vinyl groups, and the second reactor copolymerizes the macromonomers in situ onto the polyethylene backbone, forming long-chain branched structures grafted with terminal vinyl groups. The polyethylene provided by this invention maintains a narrow molecular weight distribution while possessing excellent processing performance, combining high strength and high melt strength, and can be widely used in blown films, injection molded products, pipes, and monofilament resins, among other fields.

The application belongs to the field of plastic materials, and discloses a coal-based solid waste stone-plastic composite master batch and a preparation method thereof. The preparation method comprises the following steps: after coal-based solid waste is crushed and calcined and activated, the coal-based solid waste is added into a modified solution containing a boric acid compound and a lignin sulfonate, and heated and stirred to react, so that modified particles are obtained; polyolefin and an acid anhydride compound are mixed and heated to react, so that acid anhydride modified polyolefin is obtained, then an epoxy-based chain extender is added, and heating reaction is continued, so that modified molten liquid is obtained; the modified particles are added into the modified molten liquid for melting and stirring, so that mixed slurry is obtained, then an amine crosslinking agent and an epoxy borate are added, and heating, stirring, extrusion, cooling and granulation are performed, so that the coal-based solid waste stone-plastic composite master batch is obtained. The coal-based solid waste stone-plastic composite master batch prepared by the above method can maintain good toughness while maintaining a high content of coal-based solid waste.

This invention discloses a glass fiber reinforced polypropylene material, its preparation method, and its application. The glass fiber reinforced polypropylene material comprises the following components in parts by weight: 55-95 parts polypropylene resin, 10-35 parts glass fiber, and 1-5 parts compatibilizer; wherein the polypropylene resin contains block copolymer polypropylene A and block copolymer polypropylene B in a weight ratio of (2-4):1; the average molecular weight M of block copolymer polypropylene A is... w The mass fraction of the copolymerized ethylene propylene diene monomer (EPDM) phase is 10%-20%, with a molecular weight of 200,000-290,000; the average molecular weight M of the block copolymerized polypropylene B is... w The mass fraction of the copolymerized ethylene propylene diene monomer (EPDM) phase is 11%-17% with a molecular weight ≥340,000. This invention produces glass fiber reinforced polypropylene materials by selecting block copolymers A and B with specific average molecular weights and EPDM phase contents. These materials exhibit strong tensile properties, flexural properties, and unnotched impact resistance under low-temperature conditions.

This invention relates to an environmentally friendly lightweight blow-molded container, which has a multi-layer co-extrusion structure. The multi-layer co-extrusion structure includes at least one foam layer, an inner surface support layer, and an outer surface support layer. The foam layer is located between the inner and outer surface support layers. The foam layer is made of the following components by weight: 100 parts of waste plastic scrap PP, 1-3 parts of diallyl isocyanurate, 5-10 parts of acrylamide, 0.3-0.5 parts of initiator, 3-10 parts of foaming material, and 0-15 parts of other additives. The foaming material includes a support structure, which is a three-dimensional porous material. This invention achieves lightweighting through foaming while utilizing waste plastics for high-value conversion. The foamed product of this invention has stable pores that are not easily collapsed, and has good thermal insulation properties.

The present application provides a kind of flame-retardant high toughness high branched polyolefin protective film and its preparation method.Base film includes basic polyolefin resin, high branched polyolefin component, polyolefin elastomer, halogen-free intumescent flame-retardant composition, compatibilizer, catalytic charring synergist, anti-dripping agent and stabilizer and processing aid.Halogen-free intumescent flame-retardant composition includes microencapsulated ammonium polyphosphate, nitrogen source, char-forming agent and aluminum hypophosphite and / or diethyl aluminum hypophosphite.Melt strength is improved by high branched polyolefin, toughened by polyolefin elastomer, and carbon layer, powder dispersion and film surface quality are improved by surface treatment of flame retardant, catalytic charring synergist, staged addition and vacuum exhaust.The protective film can be single-layer cast film, single-layer blown film or multi-layer co-extruded film, with thickness of 30-250 μm, which can be used for surface protection and flame-retardant isolation of electronic appliances, power battery module, metal plate, building decoration plate and industrial equipment.

The application discloses a kind of wear-resistant anti-adhesion injection molding machine composite modified material and preparation method thereof, belong to high polymer composite material technical field.The material includes by weight parts: thermoplastic resin matrix 100 parts;Multi-dimensional space hybrid reinforcing body 5~25 parts;Friction reactivity nano repair agent 3~12 parts;Three-layer core-shell structure anti-adhesion rheological agent 2~8 parts;Interface compatibilizer 0.5~3 parts.The repair agent is composed of specific oxide, can occur solid phase reaction under injection molding machine operating temperature and shear to realize in-situ repair.The anti-adhesion rheological agent is three-layer core-shell structure with carbon nanotube core, GMA-fluorine-containing acrylic ester copolymer intermediate layer and perfluoropolyether shell layer.The material of the application introduces friction-induced solid phase reaction repair mechanism and three-layer core-shell compatibility design, solves the existing material repair mechanism mismatch, anti-adhesion component and matrix compatibility poor, formula process is not clear and other problems.

The application discloses a kind of multilayer co-extrusion thermoplastic elastomer foamed film and preparation method thereof, and relates to the technical field of foamed material.A kind of multilayer co-extrusion thermoplastic elastomer foamed film includes top layer, middle layer, bottom layer, and the middle layer includes the following components: thermoplastic elastomer; Nucleating agent; Chain extender; Antioxidant.A kind of preparation method of multilayer co-extrusion thermoplastic elastomer foamed film includes the following steps: after the components of middle layer are mixed uniformly, then in top layer extruder and bottom layer extruder, compatible agent and polyethylene are added; Physical foaming agent is added to middle layer extruder, then it is co-extruded through co-extrusion die, after being cooled quickly by flow roller, air knife, traction, winding, multilayer co-extrusion thermoplastic elastomer foamed film is obtained.The application solves the problems of low melt strength of existing thermoplastic elastomer, too fast gas escape, low foaming ratio, uneven cell and easy cell rupture.

The invention relates to a fluoride-free flame-retardant polyphenyl ether resin composition as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The resin composition comprises the following raw material components in parts by weight: 67-80 parts of polyphenyl ether resin; 3 to 10 parts of HIPS (High Impact Polystyrene) resin; 10 to 16 parts of a phosphate ester flame retardant; 3 to 8 parts of cross-linked styrene toughening master batch; 1-3 parts of an inorganic nano flame retardant; 0.2 to 0.5 part of an antioxidant; 0.1 to 0.5 part of a light stabilizer; and 0.5 to 1.0 part of a lubricant. Compared with the prior art, the fluoride-free flame-retardant polyphenyl ether resin composition disclosed by the invention solves the problems that the conventional flame-retardant polyphenyl ether resin needs an anti-dripping agent PTFE for synergistic flame retardance but cannot meet the PFAS prohibition, and the fluoride-free flame-retardant polyphenyl ether scheme adopting phosphonitrile for flame retardance needs high cost, and has a wide application prospect.

The invention discloses low-gram-weight polylactic acid-based high-speed coated paper and a preparation method thereof. The low-gram-weight polylactic acid-based high-speed coated paper comprises a body paper layer and a polylactic acid resin layer coated on the body paper layer, the polylactic acid resin layer comprises the following raw materials in parts by weight: 60-90 parts of polylactic acid, 0-40 parts of a polylactic acid modified material, 0.5-2 parts of a chain extender, 0.1-1 part of a lubricant and 0-2 parts of a compatilizer; the polylactic acid modified material comprises polylactic acid and a high polymer with low glass transition temperature in a mass ratio of (0.1-1): (1-4); the high polymer with low glass transition temperature is selected from one or more of polycaprolactone, hydroxyhexanoate and polymethyl ethylene carbonate. By optimizing the molecular structure of the polylactic acid, the heat stability and processing fluidity of the polylactic acid are enhanced, the lamination speed is remarkably increased, the lamination gram weight is reduced, efficient production is ensured, and meanwhile the production cost is reduced.

This invention relates to the field of polymer materials, and discloses a modified polyether ester, its preparation method and application, an elastomer additive, and an elastomer. The modified polyether ester contains structural unit A as shown in formula (I) and structural unit B as shown in formula (II), where R1 is an alkylene group having 2-10 carbon atoms, m is an integer from 5-100, n is an integer from 10-125, and R2 is hydrogen or an alkyl group having 1-5 carbon atoms; the terminal carboxyl group content of the modified polyether ester is not higher than 5 mol / t. This modified polyether ester can efficiently load elastomer additives, resulting in high activity stability of the elastomer additives, thereby improving the modification effect of the elastomer additives on the elastomer, and enabling the multiple reuse of elastomer products. Formula (I), Formula (II).

The application relates to a degradable polyester fiber layered sound-absorbing board and a preparation method thereof, and belongs to the technical field of sound-absorbing boards; a photosensitive chain extender is prepared, the photosensitive chain extender can participate in ester exchange reaction of polyester fiber synthesis to modify the polyester fiber, and the melt strength of the polyester fiber after melting is improved. The probability of dripping or even breaking of the polyester fiber melt in the spinning process is reduced, and the stretching resonance problem of the polyester fiber melt due to external tension fluctuation in the stretching process is avoided. The modified polyester fiber can be spun into fiber with lower fineness and more uniform thickness, and the sound-absorbing board prepared by using the modified polyester fiber can increase the specific surface area and flow resistance of the board, so that the sound-absorbing efficiency of the sound-absorbing board is improved.

The invention discloses a machinable PETG composite foam material and a preparation method thereof. The preparation method of the PETG composite foam material mainly comprises the following steps: drying 100 parts by weight of PETG resin, 5-20 parts by weight of calcium carbonate, 5-20 parts by weight of a flexibilizer and 0.5-3 parts by weight of a chain extender, and then carrying out melt blending to obtain modified PETG particles; the dried modified PETG particles are added into an injection molding machine, supercritical nitrogen is introduced, and the PETG composite foaming material is obtained through a melt blending and under-injection molding method. According to the method, calcium carbonate, a flexibilizer and a chain extender are used for synergistically modifying PETG, and a supercritical nitrogen injection molding foaming process is combined, so that the technical problems that the PETG melt is low in strength, easy to break and collapse in foaming, poor in toughness and the like are effectively solved, and the PETG composite foaming material prepared by the method has good expandability and machinability, and is suitable for industrial production. The material can be applied to eyebrow pencil shell packaging materials.

This invention relates to the field of propylene polymerization, and discloses a method for preparing polypropylene and its applications, as well as polypropylene and its applications. The method includes: S1, conducting a first polymerization reaction of propylene in the presence of a first molecular weight regulator, a first external electron donor, a functional external electron donor, and a catalyst system to obtain polymer A; S2, conducting a second polymerization reaction of propylene in the presence of a second molecular weight regulator, a second external electron donor, and polymer A to obtain polypropylene; the amount of the first molecular weight regulator is less than the amount of the second molecular weight regulator. This method introduces a functional external electron donor during the first polymerization process, while simultaneously controlling the first and second external electron donors to meet specific types and controlling the amount of molecular weight regulator at different polymerization stages, enabling the obtained polypropylene to possess both good processing properties and heat resistance.