592 results about "Ionomer" patented technology

The invention provides a novel polynorbornene anion exchange ionomer containing a polar functional group as well as a preparation method and application of the novel polynorbornene anion exchange ionomer. The polynorbornene has excellent thermal stability and chemical stability. Meanwhile, the AEI main chain of the polynorbornene has no aryl group, so that the adsorption influence caused by the aryl group is avoided. The synthesized addition polynorbornene AEI in the form of quaternary ammonium salt can be dissolved in a low-boiling-point solvent, and it is ensured that a membrane electrode can be prepared through a solvent casting method. Besides the solubility of the AEI, the addition polynorbornene-based AEI in the form of quaternary ammonium salt is modified by utilizing a thiol-ene click reaction, an anion exchange ionomer containing a polar functional group can be prepared, the interaction between the AEI and an electrolytic catalyst is improved, the reaction is simple and easy to operate, the universality is high, and the method is suitable for industrial production. And the current density in the AEMWE system containing the AEI can be effectively improved.

The invention relates to an anion exchange membrane based on isopropyl piperidone and biphenyl and a preparation method of a membrane electrode, the preparation method comprises the following steps: respectively dissolving an aromatic monomer and IPD in a first solvent, and mixing to obtain a mixed solution, the aromatic monomer being BP or TP; dropwise adding an acidic initiator into the mixed solution for reaction at the reaction temperature of-5 DEG C to 0 DEG C to obtain a nitrogen heterocyclic ring polymer intermediate; adding a quaternization reagent into the nitrogen-containing heterocyclic ring polymer intermediate to realize quaternization modification of nitrogen atoms to obtain a quaternization ionomer; and forming a film to obtain the AEM film. The preparation method of the membrane electrode comprises the following steps: respectively forming a cathode catalyst layer and an anode catalyst layer on two opposite sides of an AEM membrane through ultrasonic spraying to obtain the MEA. The AEM membrane and the MEA obtained according to the invention have the characteristics of excellent stability and high water electrolysis performance, can significantly improve the efficiency and durability of AEMWE, and are suitable for the fields of hydrogen production by water electrolysis and the like.

The present invention provides a catalyst-layer-equipped electrolyte membrane and an application of the same, said catalyst-layer-equipped electrolyte membrane comprising: an anode catalyst layer containing an ionomer and an anode catalyst component that is composed of iridium-containing manganese dioxide, the molar ratio of iridium to manganese in the anode catalyst component being 0.011-0.182, and the logarithm log(amount of ionomer / amount of anode catalyst component) of the ratio of the amount of the ionomer to the amount of the anode catalyst component being −1.40 to −0.46; a proton exchange membrane; and a cathode catalyst layer.

The invention relates to a membrane electrode with high oxygen permeability and a preparation method thereof, the membrane electrode comprises a proton exchange membrane, an anode catalyst layer and a cathode catalyst layer, the anode catalyst layer and the cathode catalyst layer are arranged on two sides of the proton exchange membrane, and anode catalyst slurry comprises an anode catalyst, an ionomer and a dispersing solvent in a mass ratio of 1: (1-10): (10-1000); the cathode catalyst slurry comprises a cathode catalyst, an ionomer, an ionic liquid and a dispersing solvent in a mass ratio of 1: (1-10): (1-10): (10-1000). Compared with the prior art, in order to solve the problem that oxygen mass transfer of a porous carbon carrier in a fuel cell catalyst layer is difficult, the method that ionic liquid and ionomer are mixed in advance, then slurry is prepared, and the slurry is sprayed to prepare the membrane electrode is adopted, so that a compact structure formed by an ionomer membrane on the surface of a catalyst is weakened, and the distribution uniformity of the ionomer membrane is improved; the local oxygen mass transfer resistance is obviously reduced, and the performance of the fuel cell under high current density is improved.

The present invention provides an organic phosphonic acid betaine and a preparation method thereof, specifically an ammonium phosphonic acid betaine containing a glycidyl group. The organic phosphonic acid betaine can be used as a functional monomer for free radical grafting modification of the surface of a polymer material such as polyolefin, or can be mixed with acrylate, acrylonitrile or other olefin monomers for copolymerization to prepare an amphoteric ionomer. The organic phosphonic acid betaine can also be used for ring-opening grafting modification of polymer materials such as starch, cellulose, polyurethane, and polyamide containing amino or hydroxyl groups in their structures. At the same time, the phosphonic acid betaine imparts functional effects such as zwitterionization, hydrophilicity, antibacterial properties, and antifouling properties to the obtained polymer material. The organic phosphonic acid betaine also has high chemical stability in acidic and alkaline water environments.

The invention discloses an ionomer enhanced PA composite material and a preparation method thereof in the field of polyamide materials. The ionomer enhanced PA composite material comprises the following components in parts by weight: 70-80 parts of PA6, 20-30 parts of an ethylene-octylene copolymer, 1-3 parts of an enhancer, 0.02-0.05 part of an initiator and 0.05-0.1 part of an antioxidant. An ionomer reinforcing agent, ionic bonds and hydrogen bonds are added in a PA6 and POE system, so that the reinforcing agent and PA6 form a'synergistic stress network ', local stress concentration is reduced, strength is improved, 'strength-toughness-rigidity' synergistic improvement is achieved, an ionomer structure of the reinforcing agent is compatible with polar PA6 and a non-polar ethylene-octene copolymer at the same time, and the strength of the POE is improved. The phase separation defect is eliminated, and the material performance stability is high.

Proton exchange membranes are described. The proton exchange membrane includes: a reinforcing membrane; a continuous non-porous hydrogen recombination catalyst coating, the continuous non-porous hydrogen recombination catalyst coating comprising a mixture of a hydrogen recombination catalyst and a proton conducting ionomer; and a continuous non-porous cross-linked polyelectrolyte multilayer coating, the continuous non-porous cross-linked polyelectrolyte multilayer coating comprising alternating layers of a polycationic polymer and a polyanionic polymer. Catalyst coated membranes incorporating proton exchange membranes and methods of making proton exchange membranes are also described.

The invention belongs to the technical field of high polymer materials, and particularly relates to a polylactic acid blended composite material applied to automotive interiors and a preparation method thereof. The raw material of the material is polylactic acid modified ionomer or polylactic acid modified copolymer; a biodegradable polyester or elastomer; a chain extender; an anti-hydrolysis agent; an antioxidant; a nucleating agent; and a lubricant. The preparation method comprises the following steps: carrying out vacuum drying on the polylactic acid ionomer or the polylactic acid modified copolymer and the biodegradable polyester or the elastomer; uniformly mixing the dried polylactic acid ionomer or polylactic acid modified copolymer, biodegradable polyester or elastomer, a chain extender, an antioxidant and a lubricant to obtain a mixture; melting, blending and extruding the mixture; water in the material is pumped out at the tail end of an extruder in a vacuumizing mode, and the polylactic acid blending composite material is obtained after the procedures of water cooling, grain-sized dicing and drying. The material disclosed by the invention has excellent characteristics of high rigidity, high toughness, heat resistance, ultraviolet resistance, antibacterial property and the like, and can be applied to the field of automotive upholstery.

In one aspect, the present disclosure relates to a flame retardant plastic composition comprising a polymer component and a brominated flame retardant (BrFR), where the BrFR comprises one or more particles at least partially encapsulated by a thermoplastic toughening agent. In some aspects, the encapsulation can take the form of a core-shell structure wherein the shell has an average thickness of about 5 nm to 10 [mu] m. The thermoplastic toughening agent can be selected from the group consisting of styrenic block copolymers, thermoplastic polyurethanes, nitrile rubbers, acrylic elastomers, copolyester elastomers, thermoplastic polyether ester elastomers, thermoplastic amide ether elastomers, chlorinated rubbers, ionomers, thermoplastic vulcanizates, and combinations thereof. The flame-retardant plastic composition additionally comprises a filler and / or a compatibilizer. A method for preparing the flame retardant plastic composition and articles made from the composition are also disclosed.

The invention discloses an anion exchange membrane electrode and a preparation method and application thereof, and belongs to the technical field of new energy material and catalytic electrode preparation, the method comprises the following steps: S1, preparing an anode catalyst slurry comprising a hydrophobic covalent organic framework material, an anode catalyst, an anion exchange ionomer and a solvent; s2, preparing a cathode catalyst slurry of which the components comprise a cathode catalyst, an anion exchange ionomer and a solvent; and S3, respectively spraying or coating the anode catalyst slurry and the cathode catalyst slurry on two side surfaces of an anion exchange membrane or a gas diffusion layer, and carrying out heat treatment to obtain the anion exchange membrane electrode. The method provided by the invention can solve the problems of large gas-liquid-ion three-phase mass transfer resistance, easy shielding of active catalytic sites by ionomers and unbalanced water management in the membrane electrode assembly in the existing AEMWE device.

The invention relates to a system and a method for measuring the content of free ionomers in high-solid-content catalyst slurry of a fuel cell, and belongs to the technical field of analysis of catalyst slurry of the fuel cell. Separating the catalyst slurry into a supernatant containing free ionomers and a catalyst aggregate precipitate; the filtering device is used for filtering the supernate and removing residual solid particles in the supernate to obtain filtrate; the evaporation device is used for carrying out drying treatment on the filtrate obtained after filtration, and completely evaporating solvent components in the liquid to obtain free ionomer solids; and the weighing device is used for accurately weighing the materials in the centrifuging, filtering and drying processes. Compared with the prior art, the system and the method for measuring the content of the free ionomer in the catalyst slurry of the fuel cell, which are provided by the invention, are accurate in measurement result and wide in applicability through the processes of centrifuging, filtering and drying and accurate weighing.

The invention discloses a hydrophobic gas diffusion electrode loaded with silver nanoparticles and application of the hydrophobic gas diffusion electrode in electrocatalytic carbon dioxide reduction, and belongs to the technical field of electrocatalysis. The hydrophobic gas diffusion electrode comprises a gas diffusion layer and a catalyst layer sprayed on the gas diffusion layer; the catalyst layer comprises a silver nanoparticle catalytic material, a first ionomer and a second ionomer; wherein the first ionomer is a fluororesin ionomer, and the second ionomer is a quaternized polysulfone ionomer. A system for preparing CO by reducing CO2 through electro-catalysis is constructed, the system comprises an MEA electrolytic cell, a cathode, an anode and an anion exchange membrane, and the cathode adopts the hydrophobic gas diffusion electrode loaded with the silver nanoparticles. The preparation method is mild in preparation condition and environmentally friendly, the modified hydrophobic gas diffusion electrode has high hydrophobicity, efficient conversion of CO2 can be achieved under the high current density, FECO can reach 96.5% under the high current density, and excellent catalytic performance is shown.

The invention relates to the field of fuel cell catalysts, and discloses a method for improving a membrane electrode catalyst layer of a proton exchange membrane fuel cell by using a sulfonic acid group modified carbon material, which comprises the following steps: adding a carbon material into an acid solution, carrying out reflux reaction, washing and drying to obtain a carbon material with an oxygen-containing functional group; adding the carbon material containing the oxygen functional group into an organic solvent for dispersion, adding an organic matter containing a sulfonic acid group after reaction, and performing condensation reaction to obtain a sulfonic acid group modified carbon material; and adding the sulfonic acid group modified carbon material into the proton exchange membrane fuel cell slurry to prepare the sulfonic acid group modified material improved proton exchange membrane fuel cell membrane electrode. A sulfonic acid group and water molecules form a hydrogen bond under a low-humidity working condition, so that the water retention capacity of the catalyst layer is improved, and the proton conduction capacity is improved; under the high-humidity condition, due to the ionization charge repulsion effect of sulfonic acid groups and ionomers, the adsorption of the ionomers on the surface of the carbon material is reduced, the porosity of the catalyst layer is improved, the discharge of redundant water is facilitated, and the gas transmission rate is increased.

A resin composition that contains: (A) a bio-polyethylene resin; (B) an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 60 mol %; and (C) at least one component selected from the group consisting of an ethylene-vinyl acetate copolymer, an acid-modified ethylene-α-olefin copolymer, an ethylene-unsaturated monocarboxylic acid copolymer, an ionomer of the ethylene-unsaturated monocarboxylic acid copolymer, an ethylene-vinyl alcohol copolymer having an ethylene content of 70 to 90 mol %, and a hydrotalcite compound. The resin composition employs a bio-polyethylene resin and yet can suppress gumming and provide a formed product having an excellent appearance.

The invention belongs to the technical field of fuel cell membrane electrode preparation, and particularly discloses a preparation method for improving fuel cell catalyst layer ionomer distribution, which comprises the following steps: placing a carbon nanotube in dilute nitric acid, carrying out uniform ultrasonic dispersion, then carrying out oil bath heating, carrying out continuous acidification treatment, then carrying out suction filtration, and drying to obtain a carbon nanotube catalyst layer; carbon nano tube powder subjected to acidizing treatment is obtained; mixing the acidized carbon nanotube powder with a Nafion solution in proportion, and removing a solvent through rotary evaporation to obtain a carbon nanotube-Nafion compound; mixing the carbon nanotube-Nafion compound with a commercial Pt / C catalyst, deionized water and ethanol in proportion, and performing ultrasonic treatment under an ice bath condition to obtain uniformly dispersed cathode catalyst slurry; and spraying the uniformly dispersed cathode catalyst slurry on the cathode side of the proton exchange membrane to obtain the catalyst layer for improving ionomer distribution.

The application discloses a PEM water electrolysis hydrogen production membrane electrode and a preparation method thereof, and relates to the technical field of water electrolysis hydrogen production. The PEM water electrolysis hydrogen production membrane electrode comprises a proton exchange membrane and cathode and anode catalyst layers located on both sides of the proton exchange membrane, wherein the cathode catalyst layer and the anode catalyst layer both comprise a catalyst, a perfluorosulfonic acid ionomer, a solvent and a perfluorosulfonic acid ionomer dispersion promoter; and the perfluorosulfonic acid ionomer dispersion promoter is at least one of dimethyl sulfoxide, tetrahydrofuran and N-methyl pyrrolidone. The PEM hydrogen production membrane electrode catalyst layer prepared by the application has the dispersion promoter of the ionomer added, the dispersion degree of the ionomer in the catalyst layer is increased, a good catalyst / ionomer microporous structure catalyst layer is constructed, the transmission resistance of the gas and water is reduced, and the performance of the membrane electrode is improved. The preparation method adopted by the application does not need special treatment process and equipment, is simple and fast in operation, and is easy to realize batch production.

The invention relates to the technical field of hydrogen production by electrolyzing water, and provides a preparation method of anode catalyst slurry of PEM electrolyzed water, slurry and a catalytic layer.The preparation method comprises the steps that S1, an anode catalyst, a first ionomer and a first solvent are mixed and dispersed, and first catalyst slurry is obtained; s2, mixing and dispersing a dehydrogenation catalyst, a second ionomer and a second solvent to obtain second catalyst slurry; the dehydrogenation catalyst is a carbon-supported noble metal catalyst; and S3, mixing the first catalyst slurry and the second catalyst slurry, and carrying out homogenization treatment to obtain the anode catalyst slurry. The method has the advantages that the effects of improving uniformity, improving mass transfer and reducing hydrogen in oxygen are achieved at the same time through the cooperative arrangement of the adding of the hydrogen elimination additive, the slurry preparation process steps and the like, and the performance and the safety of the membrane electrode are improved.

The invention belongs to the field of composite materials, and discloses a high-airtightness nano injection molding polybutylene terephthalate composite material and application thereof. The composite material comprises the following components in percentage by weight: 23%-82.5% of PBT (Polybutylece Terephthalate); 5%-15% of polyarylester; 2%-8% of a reactive flexibilizer; 0.5 to 2% of an ionomer; 0-1% of an antioxidant; 0-1% of a release agent; 10%-50% of glass fiber; the PBT composite material provided by the invention can realize high and stable air tightness, and also has high aluminum alloy binding force and good mechanical properties. Meanwhile, the preparation method disclosed by the invention is simple and feasible, and is suitable for large-scale production.

The invention discloses a carbon-coated platinum-based catalyst for a fuel cell and a preparation method thereof, and the preparation method comprises the following steps: dispersing a carbon carrier and a surfactant in a water-alcohol solution to obtain a carbon carrier solution; preparing a platinum-containing precursor solution; the mass of platinum in the platinum-containing precursor is 30-70% of the mass of the carbon carrier; mixing the carbon carrier solution and the platinum-containing precursor solution, and removing the solvent to obtain platinum-loaded carbon carrier particles; immersing the platinum-loaded carbon carrier particles into a weakly alkaline buffer solution, and adding dopamine hydrochloride to form polydopamine to coat the surfaces of the platinum-loaded carbon carrier particles; the reaction product is placed in reducing gas for carbonization treatment, and the carbon-coated platinum-based catalyst is obtained. According to the prepared catalyst, the poisoning effect of sulfonic acid groups of ionomers on Pt is avoided, the problem of large oxygen mass transfer resistance is solved, and stable electric energy output provided by a fuel cell is facilitated.

The invention discloses a fuel cell dry membrane electrode and a preparation method thereof, a catalyst and an ionomer are mixed in an aqueous solution, in the directly used catalyst, platinum black particles and a carbon carrier are anchored through a surface functional group, platinum nanoparticles are good in dispersity, and in the aqueous solution, the platinum black particles and the carbon carrier are uniformly dispersed. The negative-SO3H group from the ionomer particles can attract the positively-charged Pt particles, so that the ionomer can uniformly cover the surfaces of the Pt particles, an ionomer / Pt particle interface is spontaneously formed, the ionomer can be uniformly distributed on metal active sites, on one hand, the transfer of protons to the active sites can be accelerated, the reaction kinetics can be improved, and on the other hand, the reaction efficiency can be improved; on the other hand, metal dissolution or poisoning is reduced, and membrane electrode performance and service life are improved. The use of toxic and expensive organic solvents is avoided, a more environment-friendly and lower-cost dry preparation process is adopted, proton membrane swelling in the preparation process is avoided, and the proton conductivity is improved.

The invention discloses a method for preparing a membrane electrode of a proton exchange membrane fuel cell by a template method. The method comprises the following steps: 1) selecting a nano material as a template agent; 2) fixing a template agent on a proton exchange membrane to obtain a proton exchange membrane A; 3) uniformly mixing a catalyst, a solvent and an ionomer to form catalyst ink; 4) spraying the catalyst ink on the proton exchange membrane A and drying to obtain a proton exchange membrane B; 5) placing the proton exchange membrane B in an etching solution to obtain a proton exchange membrane C; and 6) tightly attaching the proton exchange membrane C to the gas diffusion layer, and then carrying out hot pressing at high temperature and high pressure by a hot press to finally obtain the membrane electrode of the proton exchange membrane fuel cell. According to the membrane electrode prepared by the preparation method, an ordered pore channel structure can be constructed in the catalyst layer, so that the mass transfer rate of oxygen and water in the catalyst layer is improved, and the performance of a proton exchange membrane fuel cell is improved.

One embodiment of the present invention pertains to an ionomer having an acidic functional group, a fluorine-containing cyclic group containing 3-16 ring-forming atoms, and a modification layer for modifying the acidic functional group, the modification layer containing a nitrogen-containing cyclic organic compound, a polymer thereof, or a cation of the nitrogen-containing cyclic organic compound or the polymer thereof. Another embodiment of the present invention relates to a fuel cell having at least an electrode catalyst layer for a cathode, an electrode catalyst layer for an anode, and an electrolyte membrane disposed between the electrode catalyst layer for the cathode and the electrode catalyst layer for the anode, the electrode catalyst layer containing an electrochemical oxygen reduction catalyst and the ionomer according to one embodiment of the present invention. Another embodiment of the present invention relates to a method for producing an ionomer, which comprises a modification step for modifying an acidic functional group by mixing an ionomer material having an acidic functional group and a fluorine-containing cyclic group with a modifier containing a nitrogen-containing cyclic organic compound, a polymer thereof, or a cation thereof.

A proton exchange membrane for an energy conversion device, a hydrogen fuel cell stack for a vehicle, and a method for producing a proton exchange membrane. The proton exchange membrane contains a first layer of a perfluorosulfonic acid ionomer. Furthermore, the perfluorosulfonic acid ionomer contains a first additive coated with methoxy nonfluorobutane. The hydrogen fuel cell stack comprises one or more membrane electrode assemblies, each containing a proton exchange membrane.

The present invention addresses the problem of providing a fuel cell and a method for manufacturing a fuel cell in which a binder is not used when joining an electrode layer and a gas diffusion layer. In order to solve the problem, a fuel cell (1) has an electrode layer (3) and a gas diffusion layer (5) bonded to the electrode layer (3), the electrode layer (3) contains an ionomer (41), the gas diffusion layer (5) has ionomer particles (42) on at least a part of the surface facing the electrode layer (3), the ionomer particles (42) are the same as the ionomer (41) contained in the electrode layer (3), and the ionomer particles (42) are implemented by spray coating.

The invention provides a deep-sea high hydrostatic pressure resistant ionic polymer hydrophone structure and an assembly method, and belongs to the technical field of underwater acoustic sensing, the deep-sea high hydrostatic pressure resistant ionic polymer hydrophone structure comprises an upper shell, a shielding copper net, a substrate, a circuit board, a lower shell, a dry state sensitive film, a screw, a pressing plate, a positive electrode and a negative electrode, the shielding copper net is arranged at the top of the lower shell, a dry-state sensitive film is fixed on the front surface of the substrate, a circuit board is adhered to the back surface of the substrate, the substrate is inserted into the lower shell, a cavity at the lower part of the substrate is encapsulated and cured, and after the pressure-resistant shell is packaged, water is injected into the shell of the ionic polymer hydrophone and defoaming is performed. And finally, sealing and curing the water injection hole of the lower shell by using a sealant to form the ionic membrane polymer hydrophone. According to the invention, perfect packaging, low sound wave loss and good low-frequency sensitivity of the hydrophone in a deep water condition can be ensured, and the hydrophone has important popularization and application values for the work of the hydrophone in a deep sea level.

The present invention discloses a catalytic layer for a fuel cell and a preparation method thereof. The catalytic layer comprises an anode catalyst and a cathode catalyst. The anode catalytic layer comprises: a Pt-C catalyst, a high-dielectric small-molecule alcohol, sulfonated lignin-doped conductive polymer nanoparticles, a hydrophilic adhesive, an ionomer solution, and deionized water; the cathode catalytic layer comprises a catalyst, an ionomer solution, a high-dielectric small-molecule alcohol, polytetrafluoroethylene, and deionized water. The present invention can solve the technical problems of poor water management effect and poor conductivity of the water management materials used in current fuel cell catalytic layers. The preparation method is simple and convenient, greatly reducing the difficulty of preparation and the difficulty of operation for operators.

The present invention relates to a thermoplastic polyester elastomer resin composition, a method of preparing the same, and a molded article comprising the same. More particularly, the present invention relates to a thermoplastic polyester elastomer resin composition, a method of preparing the same, and a molded article comprising the same, the thermoplastic polyester elastomer resin composition comprising: 89 to 96 wt% of a thermoplastic polyester elastomer resin (A); 1.5 to 5.5 wt% of a glycidyl-modified olefin-based rubber polymer (B); and 1.5 to 5.5 wt% of an ionomer resin (C). The present invention has the effect of providing a high-quality thermoplastic polyester elastomer resin composition, a method of preparing the same, and a molded article comprising the same, the thermoplastic polyester elastomer resin composition having excellent mechanical properties and molding properties; being capable of inhibiting the generation of flow marks on the inner surface of the molded article; and thus being suitable for use in constant-velocity universal joint boots.

A membrane electrode assembly for a fuel cell includes, in this order, a cathode catalyst layer, a solid polymer electrolyte membrane, and an anode catalyst layer. The cathode catalyst layer contains at least a catalyst and a highly oxygen-permeable ionomer. At least one selected from the group consisting of the cathode catalyst layer, the solid polymer electrolyte membrane, and the anode catalyst layer contains a nitrogen-containing multidentate ligand coordinatable to an iron ion.

The present invention relates to a water electrolysis electrode, a membrane electrode assembly comprising same, and an electrolysis cell comprising the membrane electrode assembly. Provided are a water electrolysis electrode, a membrane electrode assembly comprising same, and an electrolysis cell, the water electrolysis electrode comprising: a substrate; and a catalyst layer positioned on the substrate and comprising an iridium oxide and an iridium oxide-ionomer aggregate.

The invention relates to the technical field of fuel cells, in particular to low-granularity catalyst slurry for a fuel cell and a preparation method of the low-granularity catalyst slurry. The slurry comprises the following components: a catalyst, water, an ionomer and a solvent, wherein the weight ratio of the catalyst to the water to the ionomer to the solvent is 1: (4-10): (1-4): (2-6). Through a specific ball milling dispersion method, catalyst particles can be better combined with the perfluorinated sulfonic acid resin, and the particle size of the obtained catalyst slurry is smaller.