213 results about "Chain segment" patented technology

This invention discloses a PETG co-extruded composite sheet and its preparation method. The method involves adding extruder and APET masterbatch to an extruder, then layering and combining the extruder melt and APET masterbatch melt to form a composite melt with an upper and lower layer of extruder and a middle layer of APET masterbatch. This is then shaped by roller pressing to obtain the PETG co-extruded composite sheet. During the blending process of modified polyester and modified filler, the epoxy group structure in the modified polyester molecule can react with the secondary amine in the modified filler, resulting in mild cross-linking and increasing the strength of the polyester material. The modified polyester molecular chain contains polysiloxane segments, and also has polysiloxane segments branched onto its side links. When impacted, the flexible polysiloxane segments absorb and dissipate a large amount of energy through violent movement, rotation, and entanglement. Furthermore, the nano-reinforcing points formed by the cage-like silsesquioxane structure within the molecule contribute to the excellent scratch resistance of the prepared composite sheet.

The application discloses a preparation of low-yellowing polyether modified amino silicone oil and a fabric finishing agent containing the same, and relates to amino silicone oil and application thereof. The application uses octamethylcyclotetrasiloxane and 3-piperazinylpropylmethyldimethoxysilane as key raw materials, converts original primary amino groups into secondary amino groups on the basis of traditional amino silicone oil, simultaneously pays attention to control of the molecular mass of the modified amino silicone oil, significantly improves the chemical stability and oxidation resistance of the silicone oil, and secondarily modifies the silicone oil by using allyl epoxy polyether, so that the originally non-hydrophilic amino silicone oil obtains certain hydrophilicity, and the self-emulsifying ability of the silicone oil and the stability of the emulsion are significantly improved. Through the modification, the final silicone oil molecular chain segment can be repeatedly and directionally arranged on the fiber surface in the form of alternating polyether and polysiloxane structure, so that the finishing agent has good hydrophilicity, softness and washability for finishing fabrics.

This invention relates to the field of polymer material synthesis technology, specifically to a modified PVB resin and its preparation method. The invention introduces a fluorinated acetal monoaldehyde derivative containing fluorine into the PVB resin. This derivative is mixed with n-butyraldehyde and glyoxal, thereby undergoing an acetalization reaction with the 1,3-o-diol structure of the PVB molecular chain, incorporating the fluorinated side link into the PVB molecular chain. Utilizing the high electronegativity and high C-F bond energy of fluorine atoms, it shields against the intrusion of external corrosive media, inhibits oxidative yellowing, and improves weather resistance. Furthermore, the invention introduces glyoxal as a crosslinking agent, containing dialdehyde groups, which can react between adjacent polyvinyl alcohol segments, causing slight crosslinking between the originally linear PVB resin segments, improving the resin's shielding performance, further reducing the intrusion of external corrosive media, and enhancing the stability of the PVB resin.

The present application provides a narrow molecular weight distribution PVP copolymer, and a preparation method therefor and a use thereof. The PVP copolymer has the structure represented by formula I. In the present application, NVP monomer and allyl polyoxyethylene ether are subjected to a copolymerization reaction in a redox system, and a sulfonating agent is then added to the resulting copolymer reaction solution to perform sulfonation treatment of the terminal hydroxyl groups, thereby obtaining the PVP copolymer. The present application utilizes the chain transfer effect of allyl polyether to achieve effective control of the molecular weight distribution of the PVP copolymer, and performs strongly polar ionized end-group treatment to improve the segment uniformity of the PVP copolymer. The spatial steric hindrance of the polyether side chains and the charge repulsion of the ionic groups significantly improve the adequacy of chain extension of PVP in the casting solution, so as to increase the exchange rate of the casting solvent and precipitant, and obtain a membrane pore structure with uniform pore size, high porosity, and stable structure.

The application belongs to the field of high polymer chemistry, and relates to a hyperbranched carbon dioxide-based polycarbonate as well as a preparation method and application thereof. The hyperbranched carbon dioxide-based polycarbonate is prepared by self-condensation polymerization of a monomer shown in formula I; in formula I, it is a three-arm structural unit derived from an initiator; and it is a carbon dioxide-based polycarbonate segment obtained by ring-opening addition polymerization of an epoxide and carbon dioxide. Compared with the prior art, the application has the following advantages: the application uses triethylborane catalyst and a mixture of TBD or DBU as a catalyst, efficiently catalyzes copolymerization of carbon dioxide and an epoxide monomer to prepare a hyperbranched carbon dioxide-based polycarbonate with a new structure, and improves the glass transition temperature and fat dissolving performance of the polymer.

This invention relates to the field of petroleum extraction technology, and discloses a compound and its preparation method, an acrylamide copolymer and its preparation method and application. The compound has the structure shown in formula (1): wherein M is H, sodium, potassium or NH4; 1≤n1≤12, 1≤n2≤19; the compound simultaneously has hydrophilic polyoxyethylene ether and sulfonic acid groups, as well as hydrophobic alkyl long chains, and the interfacial activity can be controlled by adjusting the length of the hydrophilic and hydrophobic segments;

The application relates to the technical field of inks, and discloses a long-acting coagulation ink formula, a preparation method and application, the ink comprising a water-based polyurethane emulsion, pigments, a defoaming agent and a dispersing agent; the water-based polyurethane emulsion formula is polytetrahydrofuran glycol, glycerol monooleate, isophorone diisocyanate, a chain extender and a hindered phenol crosslinking agent; the hindered phenol crosslinking agent is prepared and introduced into a molecular chain segment of the water-based polyurethane binder, linear water-based polyurethane macromolecules are linked in the form of chemical bonds, a crosslinked network structure is formed, molecular chain movement is limited, aggregation is not easy, gel during storage can be reduced, and the hindered phenol is linked to the polyurethane molecular chain through chemical bonds, free radicals are captured by the hindered phenol groups, and the phenomenon of ink skinning, gelation and coagulation of the polyurethane ink caused by oxidation during storage and use is avoided; the ink has excellent stability, adhesion, skinning resistance, rubbing resistance and alcohol resistance.

This invention discloses a method for preparing impact-resistant and cold-resistant polyvinyl chloride (PVC) conduit, belonging to the field of PVC material technology. In this invention, butyl rubber is complexed with dioctyl sebacate and active silica under the initiation of tert-butyl hydrogen peroxide. This complex acts as a flexible dispersed phase in the PVC matrix, effectively absorbing and dissipating impact energy and lowering the glass transition temperature of the material. This allows the conduit to maintain excellent toughness and crack resistance even at low temperatures. Furthermore, it works synergistically with impact modifiers in the system. Ethylene-vinyl acetate copolymer provides elastomer toughening, while maleic anhydride-styrene graft copolymer acts as a highly efficient compatibilizer and interfacial reinforcing agent. The compounded structure forms a toughening network, achieving toughening from molecular chain segment movement to microstructure, thus improving impact strength. Subsequent addition of reinforcing fibers of the same specification further enhances the strength of the conduit. Overall, this results in a PVC conduit with excellent strength, impact and cold resistance, and thermal properties.

The application relates to the field of high polymer materials, and particularly discloses an acrylic ester copolymer containing an ionic liquid monomer as well as a preparation method and application thereof. The ionic liquid monomer is capped with an acrylamide group or an acryloyloxy group, is connected to an acrylic ester chain segment main body through a copolymerization mode, and an acrylic ester copolymer solution is obtained. The acrylic ester copolymer solution is made into an electric debonding adhesive layer, the 180-degree peeling strength of which can be reduced by more than 90% under the condition that an applied voltage is less than or equal to 30V and an applied voltage time is less than or equal to 30s, and the performance of the adhesive layer almost does not attenuate after 100 cycles. The problem of high debonding voltage and long debonding time of the acrylic ester pressure-sensitive adhesive is solved. Through aging test, the adhesive layer has high tack, and has no problems of ionic liquid migration, precipitation and surface contamination.

The object of the present invention is to provide a polyester block copolymer resin composition that exhibits excellent flexibility and transparency, has excellent abrasion resistance, and can be processed into molded articles such as injection molded articles, extruded articles, films, fibers, nonwoven fabrics, and foams. [Solution] The present invention provides a polyester block copolymer resin composition comprising 100 parts by mass of a polyester block copolymer (A) containing 10 to 50% by mass of a high-melting-point crystalline polymer segment (a) consisting of crystalline aromatic polyester units and 90 to 50% by mass of a low-melting-point polymer segment (b) consisting of aliphatic polyether units and / or aliphatic polyester units, 0.01 to 3.0 parts by mass of an alkali metal salt of an aliphatic carboxylic acid (B), and / or 0.2 to 20 parts by mass of an ethylene copolymer (C) having a carboxylic acid metal base in its side chain, and 0.01 to 5.0 parts by mass of a modified wax (D).

This invention discloses a microcapsule, its preparation method, and its applications, belonging to the field of bioprotective materials. The microcapsule has a tertiary spherical or near-spherical particle structure, including a core layer, a shell layer covering the core layer, and satellite layers anchored to the outer surface of the shell layer. The core layer includes an active ingredient and a hydrophobic carrier medium. The shell layer is a cross-linked polyurethane-polyurea wall material formed by interfacial polymerization of polyisocyanate and polyols or polyamines containing hydrophilic segments. The satellite layers include active units and bridging and stabilizing units. The active units include benzalkonium chloride or benzyl chloride. The satellite layers exist in the form of nanoparticles or molecular clusters with a size of 10-150 nm. This invention, applied to bioprotective materials, solves the problem of efficient co-loading and intelligent sequential release of multipolar active substances in existing microcapsules. It possesses antiviral, antibacterial, antifungal, and anti-mite functions, a long service life, and features controllable and reproducible processes.

The application belongs to the technical field of marine functional polymer antifouling materials, and discloses an acrylic metal salt resin containing silicone and a capsaicin derivative structure, a preparation method and application thereof. The acrylic metal salt resin, silicone and a compound containing the capsaicin derivative structure are combined, the viscosity of the resin is synergistically controlled by using various functional acrylate monomers, the hydrophobic silicone chain segment is effectively integrated with the capsaicin derivative structure which has antibacterial activity and hydrophilic properties, a novel acrylic metal salt resin containing silicone and the capsaicin derivative structure is prepared, the resin has multifunctional antifouling properties such as hydrophilic / hydrophobic regulation, enhanced antibacterial activity and self-polishing renewal, the raw materials are low in price, and the obtained product has excellent antibacterial performance and more than 6 months of real sea antifouling capacity.

This invention relates to the field of composite materials, specifically to a high-strength, high-temperature resistant composite material for parts and its preparation method. It addresses the problems of poor high-temperature resistance and insufficient mechanical properties in existing composite materials. This composite material incorporates fluorobiphenyl-naphthylfuranyl polyaryletherketone, multi-walled carbon nanotubes, and polyetheretherketone. The preparation of fluorobiphenyl-naphthylfuranyl polyaryletherketone involves first synthesizing bis(trifluoromethyl)-biphenyl-dibromonaphthalene and reacting it with 5-formaldehyde-furan-2-boric acid to obtain dialdehyde-furanylnaphthalene-bis(trifluoromethyl)biphenyl. The aldehyde group then reacts with 4-aminophenol to obtain dihydroxyfuranylnaphthalene-bis(trifluoromethyl)biphenyl, which is then polymerized with 4,4'-difluorobenzophenone to obtain fluorobiphenyl-naphthylfuranyl polyaryletherketone. The rigid structure reduces chain segment movement, improves tensile strength and modulus, and enhances the polymer's high-temperature resistance, thereby improving the overall durability and reliability of the material.

The present application relates to the technical field of polyester material modification, and particularly relates to a high-transparency polyethylene naphthalate material, a preparation method and application, aiming at the problems of fast crystallization rate of the PEN material in the process of processing and molding, easy crystallization of thick products, light transmittance reduction caused by the crystallization, and insufficient material toughness, the present application introduces a diol monomer containing a side group and a flexible chain segment diol monomer into the PEN melt polycondensation process for copolymerization, wherein the diol containing a side group introduces a steric hindrance structure in the molecular chain to destroy the regular packing of the PEN molecular chain, thereby inhibiting the material crystallization behavior and improving the light transmittance of the thick product; the flexible diol introduces a flexible chain segment in the molecular chain to increase the free volume of the molecular chain and improve the molecular chain movement ability, thereby improving the material toughness. Through the above-mentioned synergistic copolymerization modification method, the crystallization tendency of the PEN material can be effectively reduced, the obtained PEN thick product has excellent light transmittance and toughness at the same time, and is suitable for the preparation of high-performance transparent polyester products.

The application provides a freezing-resistant food packaging bag and a preparation method thereof. The food packaging bag comprises the following raw materials in parts by mass: 100 parts of low-density polyethylene, 1-5 parts of modified filler and 0.1-1 parts of antioxidant. The surface of the modified filler is grafted with a copolymer chain segment of long straight-chain alkyl methacrylate and branched-chain alkyl methacrylate, wherein the number of carbon atoms of the long straight-chain alkyl is 12-18, and the number of carbon atoms of the branched-chain alkyl is 6-10. By introducing the chain segment formed by copolymerization of long straight-chain alkyl methacrylate and branched-chain alkyl methacrylate on the surface of the modified filler, the filler can not only play a role in dispersing stress and hindering crack propagation in the polyethylene matrix, but also reduce the induction of the filler interface to local regular crystallization of polyethylene, thereby reducing the tendency of forming a high-crystallinity and high-rigidity region around the filler, and improving the impact resistance and freezing resistance of the food packaging bag in a low-temperature environment.

The application discloses a polyurethane adhesive containing phosphorus-silicon synergistic flame-retardant structure, which is prepared from the following raw materials in parts by weight: polyol 50-80 parts, isocyanate 20-40 parts, end-hydroxyl phosphorus-silicon synergistic flame-retardant structure monomer 5-20 parts, chain extender 2-8 parts, and catalyst 0.1-1 part; the end-hydroxyl phosphorus-silicon synergistic flame-retardant structure monomer is a dihydric alcohol compound containing phosphorus and silicon, which is prepared from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and vinyl silane as main raw materials, and the general formula of the molecular structure is HO-R-Si(OR')3; wherein R is an organic chain segment containing a DOPO structural unit, and R' is methyl or ethyl. The application synthesizes a phosphorus-containing dihydric alcohol with a clear structure and a hydrolysable silane group, and prepares a main-chain phosphorus-silicon-containing intrinsic flame-retardant polyurethane through a copolymerization mode by taking the dihydric alcohol as a reactive monomer.

The application discloses a copolymerized rigid structure polymer gas separation membrane, which is obtained by copolymerization of 2,3,5,6-tetrafluoro-p-phenyldinitrile and 4-(9,9'-spirobi[fluorene]-2-yl)-2,3,5,6-tetrafluorobenzonitrile as a double ligand and monomer 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane. The copolymerized rigid structure polymer gas separation membrane contains a large rigid polycyclic aromatic ring structure and a symmetrical twisted spiro ring structure on a main chain structure, increases the interchain distance and the segment rigidity in the membrane, limits the activity of the segment in the membrane, and the bulky aromatic ring can expand the segment, effectively inhibits the swelling and plasticizing effect of the high-pressure easily-condensed gas such as carbon dioxide on the membrane, enhances the anti-plasticizing ability, reduces the loss of the gas flux of the separation membrane, improves the physical aging performance of the membrane, and thus prolongs the service life of the membrane.

The application discloses a water-based polyurethane with good water resistance and a preparation method thereof, and comprises the following preparation steps: (1) vacuum dehydration of polyol, anionic hydrophilic chain extender and nonionic hydrophilic chain extender containing polyoxyethylene side chains, and then polymeric reaction of polyisocyanate to obtain a polyurethane prepolymer; (2) dispersion of the polyurethane prepolymer into water under high-speed stirring to obtain a prepolymer emulsion; and (3) dropwise addition of a mixed solution of a non-water-soluble diamine-based post-chain extender containing a hydrophobic chain segment and an organic solvent into the prepolymer emulsion, and stirring reaction to obtain the water-based polyurethane with good water resistance. The water-based polyurethane prepared by the application has the advantages of excellent stability, small particle size and good water resistance.

This invention discloses a self-crosslinking oil-resistant fluorosilicone gel, its preparation method, and its applications, belonging to the field of special polymer materials technology. The preparation method of the gel includes: ring-opening copolymerization of trifluoropropylmethylcyclotrisiloxane and octylmethylcyclotetrasiloxane under alkaline catalysis to obtain a prepolymer; then reacting it with 3-(methacryloyloxy)propyltrimethoxysilane to introduce self-crosslinking groups, followed by post-treatment to obtain a self-crosslinkable prepolymer; finally, adding an organotin catalyst allows for rapid curing at room temperature to form a three-dimensional network structure. This invention imparts extremely low oil swelling rate to the material by introducing fluorinated segments, while achieving rapid self-crosslinking curing under mild conditions through molecular design. The resulting material possesses excellent oil resistance, ease of application, and good interfacial adhesion, making it suitable for sealing and plugging in harsh oil environments in aerospace, petrochemical, and other fields.

The present disclosure relates to the technical field of concrete additive, and particularly relates to a concrete retarding water reducing agent and a preparation method and application thereof; the concrete retarding water reducing agent comprises a compound A, a component B, a component C and a solvent D; wherein the structural formula of the compound A comprises a polyphosphate chain segment and a polyether chain segment; the polyphosphate chain segment and the polyether chain segment are connected through a residue of a cyclic acid anhydride; the component B comprises the following: sodium lignosulfonate, sodium dodecyl sulfate, sodium gluconate and at least one organic acid; the component C comprises at least two of the following: borax, calcium silicate, fiber, magnesium sulfate and calcium chloride; and the solvent D is a mixture of water and an organic solvent. The present disclosure provides a novel concrete-based additive which can simultaneously play a good retarding and water reducing role.

The application belongs to the technical field of polymer self-repairing elastomer materials, and specifically discloses an alkali-resistant self-repairing polyurethane hybrid elastomer and a preparation method and application thereof. The elastomer realizes the synergistic improvement of mechanical properties, self-repairing capability and environmental tolerance by synergistically introducing dynamic disulfide bonds, hydrophobic siloxane segments and rigid aromatic crosslinking structures in the same polyurethane network. The preparation method uses polyurethane precursors as raw materials, dissolves the precursors in N,N-dimethylformamide (DMF), and then casts into a film and dries, so that the process flow is simple and easy to operate. The surface scratch of the elastomer can be closed and repaired within 120 min at 60 DEG C, and the tensile property remains stable after multiple damage-repair cycles. Meanwhile, the hydrophobic siloxane-rich phase acts as a micro diffusion barrier, so that the material can still maintain the stability of chemical structure and mechanical properties under the condition of soaking in strong alkaline medium with pH = 12.

This invention discloses a high-resilience EPDM rubber sealing gasket and its preparation method, belonging to patent classification number C08K13 / 02, and relating to the field of EPDM rubber technology. The method first introduces flexible segments composed of liquid polyisobutylene and hydroxyl-terminated polybutadiene into an EPDM matrix to construct a low-energy-consumption subelastic network; then, a core-shell structure filler with silica as a rigid core and acrylate copolymer as an elastic shell is prepared to eliminate the rigid constraints of traditional filler interfaces; simultaneously, hyperbranched polyesteramide and nano-boron nitride are introduced as a synergistic system to bridge the polarity difference between the flexible segments and the core-shell filler through molecular bridging, and to reduce energy loss by utilizing the low friction and thermal conductivity of nano-boron nitride. The resulting sealing gasket exhibits high resilience, low compression set, and excellent mechanical strength.

The application discloses a PACE structure modified cap analog, which is based on the existing cap analog structure, has ribose bases or modified ribose bases at both ends, three ribose structures in the middle and a triphosphonate segment or a phosphonate segment connecting the ribose structures, and has one or more PACE structures or PACE derivative structures on the triphosphonate segment or the phosphonate segment, namely, (alkoxy)alkyl-COOH or a salt thereof with or without substitution on the triphosphonate or the phosphonate, so that the IVT yield and capping efficiency are improved, and the translation efficiency of the target mRNA is improved.

This invention discloses a heat-resistant polymer, its preparation method, and the application of cyclic imide diol compounds, belonging to the field of polymer materials. The polymer comprises a segment (I) containing a cyclic imide, a segment (II) containing a cyclic compound, and an optional third segment (III); wherein the segment (I) containing the cyclic imide can improve the heat resistance of the polymer, and its structure is such that R1 is a residue of an easily cyclized diacid, and R2 is a residue of an amino-containing diol. The heat-resistant polymer of this invention has improved heat resistance and good mechanical properties.

The present application relates to a kind of integrated descaling-passivation function polymer and its preparation method and application, belong to industrial equipment chemical cleaning and corrosion protection technical field, it is single compound with formula (I) shown as follows: D-L-P (I), wherein, D is the descaling function chain segment with number average molecular weight of 2,000 to 50,000, selected from polyacrylic acid segment, polyepoxysuccinic acid segment or phosphonated polyacrylic acid segment;P is passivation function end group, selected from the following formula (II) or formula (III) shown as follows: -R 1 -1H-benzotriazole-1-yl (II), wherein R 1 It is C1-C6 straight chain or branched alkylene;-R 2 -Si (OR 3 ) 3 (III), wherein R 2 It is C1-C3 alkylene, R 3 It is C1-C2 alkyl.The integrated descaling-passivation function polymer and its preparation method and application, by covalent bond, descaling chain segment and passivation end group are connected as single molecule, force realizes "clears a point, protects a point" sequence effect, fundamentally eliminates competitive adsorption, reaches the advantage of molecular level synergistic effect.

This invention discloses a flame-retardant modified polyethylene composite material and its preparation method, relating to the field of composite material technology. The composite material comprises: an α-olefin-ethylene copolymer, an EAA-grafted β-cyclodextrin multifunctional compatibility-inclusion carrier, a melamine-based flame retardant, and an antioxidant. This invention constructs an EAA-grafted β-cyclodextrin multifunctional compatibility-inclusion carrier with both inclusion-anchoring and compatibility-dispersion functions. β-cyclodextrin is stably fixed to the ethylene-acrylic acid copolymer backbone via esterification covalent bonds. Utilizing the size matching between the β-cyclodextrin cavity and melamine molecules, the melamine-based flame retardant is contained within the cavity through host-guest recognition, anchoring the flame retardant to the carrier backbone in the form of single molecules or nanoclusters. Based on the thermodynamic compatibility between the EAA backbone polyethylene segments and the α-olefin-ethylene copolymer, the flame retardant is uniformly integrated into the system through molecular chain entanglement and co-crystallization, achieving a uniform distribution of the flame-retardant units throughout the matrix.

The application provides a diamond wire cutting fluid and a cutting method of a silicon wafer. The diamond wire cutting fluid comprises a dispersing agent, a wetting agent and a solvent, wherein the dispersing agent is selected from one or more of structures shown in formula (I), and the wetting agent is selected from one or more of structures shown in formula (II). The chemical structures of the dispersing agent and the wetting agent in the application both comprise a branched-chain isomeric pentanol group as an end group, which can reduce the foam property of the diamond wire cutting fluid and improve the wetting property thereof. The presence of the oxirane chain segment and the oxepropylene chain segment in the wetting agent can improve the dispersion performance of the diamond wire cutting fluid and increase active adsorption sites thereof, so that the wetting agent film layer can be easily adsorbed on the surface of the silicon wafer; the alternating structure of the hydrophilic chain segment and the hydrophobic chain segment in the wetting agent makes the wetting agent have excellent wetting property and dispersion property, which can reduce the cutting resistance, the wire mark rate and the wire breakage rate. The above dispersing agent and wetting agent are compounded, so that the synergistic effect of the two can be fully exerted, and the cutting effect of the silicon wafer can be improved.

The application relates to the technical field of layered products, and discloses a high-elasticity weather-resistant composite waterproof roll material and a preparation method thereof. The roll material is a layered product, and sequentially comprises an upper reinforcing layer, a core layer and a lower reinforcing layer from top to bottom. The core layer is prepared from a bio-based polyurethane prepolymer prepared by reacting a microbial fermentation source long-chain polyester diol with an aliphatic diisocyanate, and is formed by thermal curing in cooperation with a chain extender, a catalyst and inorganic fillers. The long-chain polyester diol is obtained by polycondensation of a hydroxyl fatty acid monomer with a carbon chain length of ten to eighteen, and does not contain a double bond structure in the molecular chain. The application eliminates weak sites of photo-oxidative chain scission in the chain segment from the root of the molecular structure, blocks a chain scission path caused by ultraviolet rays, and maintains the elastic structure integrity of the roll material under long-term illumination.

The application discloses a sealing ring for a strong-alkali electrolytic cell, wherein the sealing ring body is a three-element ethylene-propylene rubber annular elastic sealing element, and the cross section of the sealing ring body comprises a high-cross-linking-density layer, a cross-linking-density gradual transition layer and a low-cross-linking-density layer along the thickness direction. The high-cross-linking-density layer is located at the medium contact side, and the dense three-dimensional cross-linking network thereof inhibits the penetration of alkali liquor; the low-cross-linking-density layer is located at the core, the molecular chain segment has a large freedom degree of movement, and the compression permanent deformation is small, so that the elastic recovery force is continuously provided; the gradual transition layer continuously transitions the cross-linking density along the thickness direction, and eliminates the interlayer shear stress in the temperature cycle. The layers are integrally combined through co-sulfurization to form a co-cross-linking network.

This invention relates to a stabilizer for preparing polycaprolactone and its application. The stabilizer is an asymmetric block copolymer comprising polycaprolactone segments and carbonyl-dependent segments, with an anchor-to-solubility ratio of 0.5 to 5.0, wherein the anchor-to-solubility ratio is the ratio of the number-average molecular weight of the carbonyl-dependent segments to that of the polycaprolactone segments. When the stabilizer of this invention is used to prepare polycaprolactone, polycaprolactone microspheres with controllable particle size range, narrow particle size distribution, and high sphericity can be obtained.