5 Must-Have Features in a Styrene Butadiene Latex for Bitumen

3.1 Conventional Performance

The general performance test results of SBR emulsified asphalt are shown in Fig. 2. When the ductility is greater than 100 cm, it is recorded 100 cm. It can be seen from the figure that: With the increase of SBR mixing, the softening point and ductility of asphalt increase, and the degree of penetration decreases. The softening point of the original emulsified asphalt is low, the degree of penetration is high, and the asphalt is brittle in the 5 ℃ ductility experiment. When the dosage of SBR goes up to 3%, the softening point of the modified emulsified asphalt has increased by 11.4% compared to the original sample of emulsified asphalt. Ductility at 25 ℃ went up increased to 100 cm, the penetration decreased to 57.6 (0.1 mm). This indicates that the low-temperature cracking resistance of SBR-modified emulsified asphalt was enhanced and the high-temperature performance was improved. This is because the addition of SBR absorbs the light oil from asphalt and produces a swelling reaction, with the asphalt changing from the solgel type to the sol-gel type. A more stable mesh structure takes shape after the molecules inside the asphalt are restrained.

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3.2 Rheological Performance

Temperature scanning tests were carried out on emulsified asphalt with varied SBR dosages. The results are shown in Fig. 3. When the temperature is determined, the addition of SBR induces reduction the phase angle (δ) of emulsified asphalt along with increment in both complex shear modulus (G*) and rutting factor (G*/sin δ). It shows that the addition of emulsified asphalt leads to a more stable spatial structure of SBR, and the reduction in light oil content lowers the temperature sensitivity of asphalt and improves the high-temperature deformation resistance and rutting resistance of asphalt as well. When SBR doping remains unchanged, the phase angle tends to increase and the complex shear modulus and rutting factor decrease with the increment in temperature. At this moment, the internal elastic component of asphalt is transformed into a viscous along with weakened deformation resistance of asphalt.

3.3 Microscopic Phase Structure

Fluorescence Microscope.

Fluorescence microscope with 400 times magnification was used to observe the distribution of SBR and asphalt. As shown in Fig. 4, fluorescence microscope image on the left hand side is darker than on the right hand side. But there is a similarity in proportion for fluorescent area which shows noticeable 3D characteristics. The emulsified asphalt image shows indistinct fluorescence emitted from the emulsifier, and the rest of the images show noticeable fluorescent material emitted from the SBR. When the dosage of SBR stands at 1%, SBR exists in the continuous phase of emulsified asphalt in the form of small particles that are well dispersed. When SBR is 3%, spatial network structure takes shape in modified emulsified asphalt along with high structural strength, improved high temperature performance and enhanced softening point as opposed to that for the conventional performance. When the dosage of SBR continues to increase to 4%, the latex begins to aggregate with a poor degree of dispersion. It shows from an overall point of view that it is best for SBR’s content to stand 3%.

Digital Image Processing of fluorescence microscope images of emulsified asphalt modified with SBR was performed using MATLAB. First of all, the fluorescence microscope images of asphalt with SBR of varied dosage were converted to grayscale image. Due to noticeable difference in gray levels between the SBR region and the background region in the image, unequal threshold segmentation of asphalt images with SBR of varied dosages was carried out to accurately extract the pixels in the target region when the original image was converted to grayscale image. The ratio of the SBR region and the background region is finally obtained, and the data obtained for each sub-block region is averaged to obtain the data results of the global image. The segmentation is shown in Fig. 5, where the black part is asphalt and the white part is SBR latex.

The binarized image of SBR emulsified asphalt was analyzed at each dosage to gain the ratio of the number of SBR pixel points to the number of pixel points of the modified emulsified asphalt in this image, namely the area percentage of SBR at each dosage. The results are shown in Fig. 6, and the formula is shown in Eq. (1) (2).

where i—pixel points of SBR in the sub-block;

j—all pixel points in the sub-block;

k—the number of sub-blocks;

R—the area percentage of the sub-block;

\(R^{ - }\)—the area percentage of the total block, namely the average of the sub-block summation.

It is indicated in Fig. 6 that the area percentage of SBR is linearly distributed with the increase of butadiene doping. The area percentage is only 5.52% at 1% of SBR doping. As the dosage of SBR increases, the area percentage also increases linearly. The percentage of area reached 12.37% at 3% of SBR. The linear fitting of the data shows that the linear pattern of the dosage of SBR and its area percentage is good, and the correlation coefficient can go up to 98.9%, which indicates that the SBR and emulsified asphalt are highly compatible.

Infrared Spectrum.

Infrared spectroscopic tests were performed on the evaporated residues of as-received emulsified asphalt and 3% SBR emulsified asphalt. These results are shown in Fig. 7. The same absorption peaks appeared in the two infrared spectral curves, including  cm−1 and  cm−1 for the absorption peaks of the stretching vibration of -CH2 alkanes, and  cm−1 and  cm−1 for the absorption peaks of the bending vibration of -CH3 alkanes. In addition to the above-mentioned absorption peaks, absorption peaks of butadiene and styrene components of the SBR composition appeared in the 3% SBR emulsified asphalt. These include 966 cm−1 for trans-butadiene, which is an out-of-plane bending vibration of trans-C-H olefin, and 699 cm−1 for styrene, which is an out-of-plane bending vibration of monosubstituted benzene ring C-H olefin. As a result, it can be seen that there is no new functional group in the emulsified asphalt of 3% SBR. Therefore, no change was found in the chemical composition of SBR and emulsified asphalt which was just subject to a physical reaction in Fig. 8.

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3.4 Adhesion Performance

According to the first law of thermodynamics, the work consumed by the molecules inside a substance to migrate to the surface is the potential energy of the molecules on the surface, called the surface free energy (\(\gamma\)). When asphalt adheres to the aggregate, the aggregate will adsorb the asphalt to reduce its own surface free energy under the influence of the force field. As a result, the surface energy is an intrinsic factor that affects the adhesion performance of asphalt. Surface energy by the polar component (also known as Lewis acid-base component, \(\gamma^{P}\)) and dispersion component (also known as van der Waals component, \(\gamma^{d}\)). The polar component in turn consists of Lewis acid (\(\gamma^{ + }\)) and Lewis base (\(\gamma^{ - }\)). The expression for the surface energy expression is show as follows:

The relation between the surface energy parameters for the liquid and bitumen are expressed as follows:

where \(\gamma_{L}\)—surface energy of the liquid;

\(\gamma_{{\text{a}}}^{d} ,\gamma_{L}^{d}\)—Dispersive component of bitumen and liquid;

\(\gamma_{{\text{a}}}^{ + } ,\gamma_{L}^{ + }\)—Lewis acid fraction of the bitumen and liquid;

\(\gamma_{a}^{ - } ,\gamma_{L}^{ - }\)—Lewis base fraction of the bitumen and liquid.

The modified emulsified asphalt with SBR of varied dosages was subjected to contact angle tests using three test liquids: water, glycerol and formamide. The surface free energy parameters of each liquid at 25 ℃ are shown in Table 3 below:

As shown in Fig. 9, the contact angle results of emulsified asphalt for each SBR dosage are slightly different. The contact angle results obtained for all three liquid reagents showed an increasing trend with the increase of SBR dosage, in which the contact angle of emulsified asphalt with water was the greatest, and the contact angle with formamide was the smallest. The coefficients of variation of the contact angles measured for the three liquids were around 2% with good reproducibility. The results of the linear analysis of the surface energy of the three liquids tested and its product with the cosine value of the contact angle are shown in Fig. 9. The figure shows that the correlation coefficients of the linear fits of the six SBR doped emulsified asphalt are all greater than 90%, indicating a good linear relationship. It indicates that the selected fluids are applicable to the surface energy testing of SBR modified emulsified asphalt.

The results of the contact angle test were used in Eqs. (3) (4), and the results are shown in Fig. 10: With the addition of SBR, the surface energy of the modified emulsified asphalt increases, and the surface free energy is more prone to decreasing when combined with the aggregate, and the asphalt-aggregate adhesion performance is better. This is due to the formation of a stable 3D network structure between the SBR and the asphalt, which enhances the adhesion of the asphalt.

3.5 Mixture Test

Mixable Test.

The performance of asphalt is subject to mixable duration when asphalt is used during a project. Required mixable duration is necessary when modified emulsified asphalt is applied to micro-surfacing. In this paper, emulsified asphalt dosage is 10%, water dosage is 5% and cement dosage is 1% in the mixable test. The above-mentioned materials were poured into 100 g of the graded aggregate and mixed to observe the mixing duration. The temperature during testing was 23 ℃ and the measured solid content of the modified emulsified asphalt was 63%. The mixing duration of the asphalt mixtures are shown in Table 4. With increasing amount of SBR, the mixing duration becomes longer along with increasing fluidity. This may be the result of formation of a more stable spatial network structure of the modified emulsified asphalt, which becomes stronger when combined with the mixture.

Abrasion Resistance and Resistance to Water Damage.

The 1 h and 6 d wet wheel abrasion tests were conducted on modified emulsified asphalt mixtures with SBR of varied dosages using the above-mentioned mixing test formulations. The wet wheel abrasion values are shown in Fig. 11. From the 1 h and 6 d wet wheel abrasion results, it can be concluded that the wet wheel abrasion values of the mixes are higher when no SBR is added. As the dosage of SBR increases, the adhesion and consolidation of asphalt and aggregate become more noticeable, and the abrasion resistance and water damage resistance of the mixture increase. As shown in Fig. 12, the cohesion between aggregates is weak when SBR is not added, and the falling of stone in shape of large particles can be noticeably found. And when the SBR dosing is 3%, the emulsified asphalt and aggregate have strong adhesion ability and the mixture loss is less. This may be the result of the stable structure formed by SBR and asphalt, which inhibits the movement of molecules within the asphalt, thus reducing the effect of water immersion on the asphalt mixture. However, when the dosage of SBR was increased to 4%, the abrasion resistance and water damage resistance of the mixture decreased instead of increasing. Asphalt mixture’s resistance to water damage was the highest at 3% SBR dosage.

Rutting Deformation Test.

The load wheel rolling test was conducted on the SBR emulsified asphalt mixture, and the rutting deformation test results are shown in Fig. 13. The width deformation rate and rutting depth rate of SBR modified emulsified asphalt mixture both become higher first and lower later with the increment SBR doping, which shows that the rutting resistance of modified emulsified asphalt mixture is enhanced first and weakened later. The improvement in the performance of the mixture is the result of the swelling reaction between SBR and asphalt, which restricts the movement of molecules within the asphalt, and the asphalt becomes harder, which enhances the rutting resistance after combining with the mixture. However, when the dosage of SBR is overly high, they will be aggregated. Consequently, the structure of modified emulsified asphalt becomes weaker and the performance of SBR-emulsified asphalt mixtures will deteriorate.

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Rutting Test.

Detailed Description As used herein, "(meth) acrylic acid …" includes acrylic acid … and methacrylic acid … and also includes diacrylic acid …, dimethacrylic acid … and polyacrylic acid …, and polymethacrylic acid …. For example, the term "(meth) acrylate monomers" encompasses acrylate and methacrylate monomers, diacrylate and dimethacrylate monomers, and other polyacrylate and polymethacrylate monomers. The term "comprising" and variations thereof as used herein is used synonymously with the term "including" and variations thereof, and is an open, non-limiting term. Although the terms "comprising" and "including" have been used herein to describe various embodiments, the terms "consisting essentially of … … (inclusive of) and" consisting of … … (inclusive of) "may be used in place of" comprising "and" including "to provide more specific embodiments, and are also disclosed. As used in this disclosure and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. The percentage ranges and other ranges disclosed herein include the endpoints of the disclosed ranges and any integers provided within the ranges. Dispersible copolymer powder Dispersible copolymer powders and compositions comprising dispersible copolymer powders are disclosed herein. The dispersible copolymer powder comprises a core polymer and a shell comprising a protective colloid polymer. A shell comprising a protective colloid polymer at least partially surrounds the core polymer. Methods of making and using the dispersible copolymer powders are also disclosed. Core polymer The core polymer can be derived from ethylenically unsaturated monomers including vinyl aromatic monomers (e.g., styrene, alpha-methylstyrene, ortho-chlorostyrene, and vinyltoluene) and conjugated dienes (e.g., 1, 3-butadiene and isoprene). The core polymer may be further derived from one or more additional ethylenically unsaturated monomers. Suitable additional ethylenically unsaturated monomers for forming the core polymer include 1, 2-butadiene (i.e., butadiene); alpha, beta-monoethylenically unsaturated monocarboxylic and dicarboxylic acids or anhydrides thereof (e.g., acrylic acid, methacrylic acid, crotonic acid, dimethylacrylic acid, ethacrylic acid, allylic acid, ethyleneMaleic acid, fumaric acid, itaconic acid, mesaconic acid, methylenemalonic acid (methacrylic acid), citraconic acid, maleic anhydride, itaconic anhydride, and methylpropanoic anhydride); esters of alpha, beta-monoethylenically unsaturated monocarboxylic and dicarboxylic acids having 3 to 6 carbon atoms with alkanols having 1 to 12 carbon atoms (e.g. acrylic acid, methacrylic acid, maleic acid, fumaric acid or itaconic acid with C1-C12、C1-C8Or C1-C4Esters of alkanols, such as ethyl, n-butyl, isobutyl and 2-ethylhexyl acrylate and methacrylate, dimethyl maleate and n-butyl maleate); acrylamides and alkyl-substituted acrylamides (e.g., (meth) acrylamide, N-t-butylacrylamide, and N-methyl (meth) acrylamide); (meth) acrylonitrile; vinyl and vinylidene halides (e.g., vinyl chloride and vinylidene chloride); c1-C18Vinyl esters of monocarboxylic or dicarboxylic acids (e.g., vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate, and vinyl stearate); c3-C6C of monocarboxylic and dicarboxylic acids1-C4Hydroxyalkyl esters, in particular acrylic, methacrylic or maleic acid, or derivatives thereof alkoxylated with 2 to 50 mol of ethylene oxide, propylene oxide, butylene oxide or mixtures thereof, or C alkoxylated with 2 to 50 mol of ethylene oxide, propylene oxide, butylene oxide or mixtures thereof1-C18Esters of alcohols (e.g., hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and methyl polyethylene glycol acrylate); and monomers containing a glycidyl group (e.g., glycidyl methacrylate). The term "(meth) acryl … … ((meth) acryl …)" as used herein comprises "acryl … … (acryl …)", "methacryl … … (methacryl …)" or a mixture thereof. The core polymer may further comprise one or more of the following additional monomers, other vinyl aromatic compounds (e.g., alpha-methylstyrene, o-chlorostyrene, and vinyltoluene); anhydrides of alpha, beta-monoethylenically unsaturated monocarboxylic and dicarboxylic acids (e.g., maleic anhydride, itaconic anhydride)Anhydrides and methyl malonic anhydride); other alkyl-substituted acrylamides (e.g., N-t-butyl acrylamide and N-methyl (meth) acrylamide); vinyl and vinylidene halides (e.g., vinyl chloride and vinylidene chloride); c1-C18Vinyl esters of monocarboxylic or dicarboxylic acids (e.g., vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl laurate, and vinyl stearate); linear 1-olefins, branched 1-olefins, or cyclic olefins (e.g., ethylene, propylene, butene, isobutylene, pentene, cyclopentene, hexene, and cyclohexene); vinyl and allyl alkyl ethers having from 1 to 40 carbon atoms in the alkyl group, which alkyl group may possibly carry further substituents, such as hydroxyl, amino or dialkylamino, or one or more alkoxylated groups (e.g. methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, vinylcyclohexyl ether, vinyl 4-hydroxybutyl ether, decyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, 2- (diethylamino) ethyl vinyl ether, 2- (di-n-butylamino) ethyl vinyl ether, methyldiglycol vinyl ether and the corresponding allyl ethers); sulfo-functional monomers (e.g., allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, vinylsulfonic acid, allyloxybenzenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and its corresponding alkali metal or ammonium salts, sulfopropyl acrylate, and sulfopropyl methacrylate); vinylphosphonic acid, dimethyl vinylphosphonate, and other phosphorus monomers (e.g., phosphoethyl (meth) acrylate); alkylaminoalkyl (meth) acrylates or (meth) acrylamidoalkylaminoalkyl esters or quaternization products thereof (e.g., 2- (N, N-dimethylamino) ethyl (meth) acrylate, 3- (N, N-dimethylamino) propyl (meth) acrylate, 2- (N, N-trimethylammonium) ethyl (meth) acrylate chloride, 2-dimethylaminoethyl (meth) acrylamide, 3-dimethylaminopropyl (meth) acrylamide and 3-trimethylammonium propyl (meth) acrylamide chloride); c1-C30Allyl esters of monocarboxylic acids; n-vinyl compounds (e.g. N-vinylformamide, N-vinyl-N-methylformamide, N-vinylpyrrolidone, N-vinylimidazole, 1-vinyl-2-methylimidazole, 1-vinyl-2-methylimidazoline, N-vinylcaprolactam, vinylcarbazole, 2-vinylpyridine and 4-vinylpyridine); monomers containing a 1, 3-diketo group (e.g., acetoacetoxyethyl (meth) acrylate or diacetone acrylamide); ureido-containing monomers (e.g., ureidoethyl (meth) acrylate, acrylamidoglycolic acid, and methacrylamidoglycolic acid methyl ether); monoalkyl itaconates; monoalkyl esters of maleic acid; a hydrophobic branched ester monomer; vinyl esters of branched monocarboxylic acids having a total of from 8 to 12 carbon atoms in the acid residue moiety (e.g., vinyl 2-ethylhexanoate, vinyl neononanoate, vinyl neodecanoate, vinyl neoundecanoate, vinyl neododecanoate, and mixtures thereof), and copolymerizable surfactant monomers (e.g., those sold under the trademark ADEKA rea). In some embodiments, the one or more additional monomers comprise (meth) acrylonitrile, (meth) acrylamide, or a mixture thereof. In some embodiments, the core polymer may comprise the one or more additional monomers in an amount from greater than 0 wt% to 20 wt%, based on the weight of the copolymer. For example, the core polymer may comprise the one or more additional monomers in an amount of from 0.5 wt% to 15 wt%, from 0.5 wt% to 10 wt%, from 0.5 wt% to 5 wt%, from 0.5 wt% to 4 wt%, from 0.5 wt% to 3 wt%, from 0.5 wt% to 2 wt%, from 0.5 wt% to 1 wt%, based on the weight of the core polymer. The core polymer may comprise one or more crosslinking monomers. Exemplary crosslinking monomers include N-alkylolamides of α, β -monoethylenically unsaturated carboxylic acids having 3 to 10 carbon atoms and esters thereof with alcohols having 1 to 4 carbon atoms (e.g., N-methylolacrylamide and N-methylolmethacrylamide); glycidyl (meth) acrylate; glyoxal-based crosslinking agents; a monomer containing two vinyl groups; a monomer containing two vinylidene groups; and monomers containing two alkenyl groups. Other crosslinking monomers may include, for example, diesters of dihydric alcohols with α, β -monoethylenically unsaturated monocarboxylic acids, where acrylic acid and methacrylic acid may in turn be employed. Examples of such monomers containing two unconjugated ethylenically unsaturated double bonds may include alkylene glycol diacrylates and dimethacrylates such as ethylene glycol diacrylate, 1, 3-butylene glycol diacrylate, 1, 4-butylene glycol diacrylate and propylene glycol diacrylate, divinyl benzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, methylene bisacrylamide, and mixtures thereof. In some embodiments, the core polymer may comprise 0.01 wt% to 5 wt% of the crosslinking agent. The core polymer may be a random copolymer or a block copolymer. In some examples, the core polymer may be a random copolymer. In some embodiments, the core polymer may be derived from ethylenically unsaturated monomers, including vinyl aromatic monomers (e.g., styrene), ethylenically unsaturated aliphatic monomers (e.g., butadiene), (meth) acrylic monomers, vinyl ester monomers (e.g., vinyl acetate), and combinations thereof. In some examples, the core polymer may comprise a styrene-butadiene copolymer (i.e., a polymer derived from butadiene and styrene monomers), a carboxylated styrene-butadiene copolymer (i.e., a polymer derived from butadiene, styrene, and carboxylic acid monomers), a styrene-butadiene-styrene block copolymer, a vinyl aromatic-acrylic copolymer (i.e., a polymer derived from a vinyl aromatic monomer such as styrene and one or more (meth) acrylate and/or (meth) acrylic monomers), a styrene-butadiene-acrylic copolymer (i.e., a polymer derived from butadiene, styrene, and one or more (meth) acrylate and/or (meth) acrylic monomers), a vinyl-acrylic copolymer (i.e., a polymer derived from one or more vinyl ester monomers and one or more (meth) acrylate and/or (meth) acrylic acid A polymer of (meth) acrylic monomers), a vinyl chloride polymer (i.e., a polymer derived from one or more vinyl chloride monomers), a vinyl alkanoate polymer (i.e., a polymer derived from one or more vinyl alkanoate monomers (such as polyvinyl acetate) or a copolymer derived from ethylene and vinyl acetate monomers)), or combinations thereof. The core copolymer present in the dispersible copolymer powder may be formed from a latex composition. The latex composition may be an aqueous latex dispersion. In particular embodiments, the core copolymer may be formed from a latex composition comprising styrene, butadiene, and optionally one or more additional monomers. The amount of styrene may be 5 wt% or more based on the weight of the core polymer. For example, the amount of styrene can be 7 wt% or more, 10 wt% or more, 20 wt% or more, 30 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, or 70 wt% or more, based on the weight of the core polymer. In some embodiments, the amount of styrene can be 95 wt% or less, 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, 70 wt% or less, 65 wt% or less, 60 wt% or less, 55 wt% or less, 50 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, or 25 wt% or less, based on the weight of the core polymer. The amount of butadiene may be 5 wt% or more of the core polymer. For example, the amount of butadiene may be 7 wt% or more, 10 wt% or more, 20 wt% or more, 30 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, or 70 wt% or more, based on the weight of the core polymer. In some embodiments, the amount of butadiene may be 95 wt% or less, 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, 70 wt% or less, 65 wt% or less, 60 wt% or less, 55 wt% or less, 50 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, 30 wt% or less, or 25 wt% or less, based on the weight of the core polymer. In some embodiments, the weight ratio of styrene monomer to butadiene monomer in the core polymer may be 5:95 to 95:5, 10:99 to 99:10, 5:95 to 80:20, 20:80 to 80:20, 5:95 to 70:30, 30:70 to 70:30, or 40:60 to 60: 40. For example, the weight ratio of styrene to butadiene may be 25:75 or greater, 30:70 or greater, 35:65 or greater, or 40:60 or greater. In some examples, the core polymer may be a random copolymer, such as a random styrene-butadiene copolymer. The core polymer may comprise carboxylic acid monomers. For example, the core polymer may comprise a carboxylated styrene-butadiene copolymer derived from styrene, butadiene, and carboxylic acid monomers. In some embodiments, the core polymer may be derived from 0 wt% or more, 0.5 wt% or more, 1.0 wt% or more, 1.5 wt% or more, 2.5 wt% or more, 3.0 wt% or more, 3.5 wt% or more, 4.0 wt% or more, or 5.0 wt% or more of carboxylic acid monomers. In some embodiments, the core polymer may be derivatized with 25% by weight or less, 20% by weight or less, 15% by weight or less, or 10% by weight or less of carboxylic acid monomers. In some embodiments, the core polymer may be derived from 0.5 wt% to 25 wt%, 0.5 wt% to 10 wt%, 1.0 wt% to 9 wt%, or 2.0 wt% to 8 wt% of a carboxylic acid monomer. Suitable carboxylic acid monomers include (meth) acrylic acid, itaconic acid, fumaric acid, crotonic acid, or mixtures thereof. In some embodiments, the core copolymer may comprise itaconic acid in an amount of 0.5 wt% to 25 wt%, 0.5 wt% to 10 wt%, or 2 wt% to 8 wt% of the core polymer. In some embodiments, the core polymer comprises one or more of the other monomers provided above. Glass transition temperature (T) of core polymer as measured by Differential Scanning Calorimetry (DSC) using a midpoint temperature as described, for example, in ASTM /82g) And may range from-90 c to less than 50 c. In some embodiments, the measured T of the core polymergIs-90 ℃ or higher (e.g., -80 ℃ or higher, -70 ℃ or higher, -60 ℃ or higher, -50 ℃ or higher, -40 ℃ or higher, -30 ℃ or higher, -20 ℃ or higher, -10 ℃ or higher, 0 ℃ or higher, 10 ℃ or higher, 20 ℃ or higher, or 25 ℃ or higher). In some cases, the measured T of the core polymergIs 40 deg.C or less (e.g., less than 40 deg.C, 30 deg.C or less, 25 deg.C or less)Lower, 20 ℃ or lower, 10 ℃ or lower, 0 ℃ or lower, -10 ℃ or lower, -20 ℃ or lower, -25 ℃ or lower, -30 ℃ or lower, -35 ℃ or lower, -40 ℃ or lower, -45 ℃ or lower, or-50 ℃ or lower). In certain embodiments, the measured T of the core polymergFrom-90 ℃ to 40 ℃, -from 90 ℃ to 30 ℃, -from 90 ℃ to 25 ℃, -from 90 ℃ to 0 ℃, -from 90 ℃ to-10 ℃, -from 80 ℃ to 25 ℃, -from 80 ℃ to 10 ℃, -from 80 ℃ to 0 ℃, -from 80 ℃ to-10 ℃, -from 60 ℃ to 25 ℃, -from 60 ℃ to 0 ℃, or from-60 ℃ to less than 0 ℃. The dispersible copolymer powder can, for example, include 25 wt% or more (e.g., 30 wt% or more, 35 wt% or more, 40 wt% or more, 45 wt% or more, 50 wt% or more, 55 wt% or more, 60 wt% or more, 65 wt% or more, 70 wt% or more, 75 wt% or more, 80 wt% or more, 85 wt% or more, 90 wt% or more, or 95 wt% or more) of the core polymer, based on the total weight of the dispersible copolymer powder. In some examples, the dispersible copolymer powder can include 95 wt% or less (e.g., 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, 70 wt% or less, 65 wt% or less, 60 wt% or less, 55 wt% or less, 50 wt% or less, 45 wt% or less, 40 wt% or less, or 35 wt% or less) of the core polymer based on the total weight of the dispersible copolymer powder. The amount of core polymer in the dispersible copolymer powder can range from any of the minimum values described above to any of the maximum values described above. For example, the dispersible copolymer powder can include 25 wt.% to 95 wt.% (e.g., 30 wt.% to 95 wt.%, 40 wt.% to 95 wt.%, 50 wt.% to 95 wt.%, 60 wt.% to 95 wt.%, 35 wt.% to 85 wt.%, 45 wt.% to 85 wt.%, 50 wt.% to 85 wt.%, 60 wt.% to 85 wt.%, or 55 wt.% to 80 wt.%) of the core polymer, based on the total weight of the dispersible copolymer powder. Shell As described herein, the dispersible copolymer powder can comprise a shell at least partially surrounding a core polymer. The shell comprises a protective colloid polymer. The protective colloid polymer may be a hydrophilic polymer, preferably a water-soluble polymer. In some embodiments, the amount of protective colloid polymer that is soluble in water at room temperature may be greater than about 40 wt.% (e.g., 45 wt.% or more, 50 wt.% or more, 55 wt.% or more, 60 wt.% or more, 65 wt.% or more, 70 wt.% or more, 75 wt.% or more, 80 wt.% or more, 85 wt.% or more, 90 wt.% or more, or 95 wt.% or more). In some examples, the protective colloid is completely soluble in water at room temperature. In some embodiments, the water solubility of the protective colloid at 20 ℃ may be greater than 1g/100g water. For example, the solubility of the protective colloid in water, as measured at 20 ℃, can be 2g/100g water or greater, 5g/100g water or greater, 10g/100g water or greater, 15g/100g water or greater, 20g/100g water or greater, or 25g/100g water or greater. The hydrophilicity of a protective colloid can be defined by the logarithm (log P) of its octanol/water partition coefficient. The higher the number, the more hydrophobic the monomer. Log P of a compound can be calculated using MedChem version 3.54 (a software package available from the Medicinal Chemistry Project, Pomona College, Claremont, Calif) of the College of pomont Pomona, california. In some embodiments, the log P of the protective colloid can be less than 1, less than 0.5, or less than 0. Weight average molecular weight (M) of the protective colloidw) May be, for example, 500Da or greater (e.g., 1,000Da or greater, 1,500Da or greater, 2,000Da or greater, 2,500Da or greater, 3,000Da or greater, 3,500Da or greater, 4,000Da or greater, 4,500Da or greater, 5,000Da or greater, 6,000Da or greater, 7,000Da or greater, 8,000Da or greater, 9,000Da or greater, 10,000Da or greater, 11,000Da or greater, 12,000Da or greater, 13,000Da or greater, 14,000Da or greater, 15,000Da or greater, 20,000Da or greater, or 25,000Da or greater). In some examples, the weight average molecular weight (M) of the protective colloidw) Can be, for example, 100,000Da or less (e.g., 90,000Da or less, 80,000Da or less, 70,000Da or less, 60,000Da or less, 50,000Da or less, 40,000Da or less, 3,000Da or less0,000Da or less, 25,000Da or less, 20,000Da or less, 19,000Da or less, 18,000Da or less, 17,000Da or less, 16,000Da or less, 15,000Da or less, 14,000Da or less, 13,000Da or less, 12,000Da or less, 11,000Da or less, 10,000Da or less, 9,000Da or less, 8,000Da or less, 7,000Da or less, 6,000Da or less, or 5,000Da or less). Weight average molecular weight (M) of the protective colloidw) Can range from any of the above minimum values to any of the above maximum values. For example, the weight average molecular weight (M) of the carbohydrate derived compoundw) May be 500Da to 100,000Da (e.g., 1,000Da to 100,000Da, 1,500Da to 50,000Da, 2,000Da to 20,000Da, 2,000Da to 15,000Da, 1,500Da to 12,000Da, 2,000Da to 12,000Da, 1,000Da to 10,000Da, 500Da to 10,000 Da). The weight-average molecular weight (M) of the protective colloids can be determined by GPC (gel permeation chromatography)w)。 Glass transition temperature (T) of protective colloid polymers as measured by Differential Scanning Calorimetry (DSC) using a midpoint temperature as described, for example, in ASTM /82g) And may be 50c or higher. In some embodiments, the measured T of the protective colloid polymergGreater than 50 ℃ (e.g., 55 ℃ or greater, 60 ℃ or greater, 65 ℃ or greater, 70 ℃ or greater, 75 ℃ or greater, 80 ℃ or greater, 85 ℃ or greater, 90 ℃ or greater, 95 ℃ or greater, 100 ℃ or greater, 105 ℃ or greater, 110 ℃ or greater, 115 ℃ or greater, 120 ℃ or greater, 125 ℃ or greater, 135 ℃ or greater, or 150 ℃ or greater). In some cases, the measured T of the protective colloid polymergIs 220 ℃ or less (e.g., 210 ℃ or less, 200 ℃ or less, 195 ℃ or less, 190 ℃ or less, 180 ℃ or less, 170 ℃ or less, 160 ℃ or less, 150 ℃ or less, 140 ℃ or less, 130 ℃ or less, 120 ℃ or less, 110 ℃ or less, or 100 ℃ or less). In certain embodiments, the measured T of the protective colloid polymergIs 50 to 220 ℃,50 to 200 ℃,50 to 150 ℃,60 to 100 ℃,60 to 195 ℃,60 to 190 ℃, 70 to 195 ℃, 80 to 195 ℃ or 85 to 190 ℃. Suitable protective colloids for use in the shell comprise water-soluble polymers, such as polyvinyl alcohol, polyvinylpyrrolidone, polysaccharides comprising cellulose and starch, gelatin, proteins (such as casein or caseinate), soy protein, lignin sulfonate, natural and synthetic gums comprising gum arabic, synthetic water-soluble polymers (e.g., acrylic acid polymers such as copolymers of poly (meth) acrylic acid and (meth) acrylates with carboxyl-functional comonomer units, poly (meth) acrylamide, polyvinylsulfonic acid), or combinations thereof. In some embodiments, the protective colloid may comprise a polysaccharide. The Dextrose Equivalent (DE) of the polysaccharide can be, for example, 5 or more (e.g., 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 10.5 or more, 11 or more, 11.5 or more, 12 or more, 12.5 or more, 13 or more, 13.5 or more, 14 or more, 14.5 or more, 15 or more, 16 or more, 17 or more, 18 or more, 19 or more, 20 or more, 21 or more, 22 or more, 23 or more, 24 or more, 25 or more, 30 or more, or 35 or more). In some examples, the DE of the polysaccharide can be, for example, 50 or less (e.g., 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 24 or less, 23 or less, 22 or less, 21 or less, 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14.5 or less, 14 or less, 13.5 or less, 13 or less, or 12.5 or less). The DE value of the polysaccharide can range from any of the minimum values described above to any of the maximum values described above. For example, the DE of the polysaccharide may be 10 to 50 (e.g., 15 to 50, 10 to 40, 10 to 35, 12.5 to 25, or 15 to 20). DE values can be determined according to the Lane and Eynon test methods (International Standard ISO : ). Suitable examples of polysaccharides that may be included in the protective colloid include maltodextrin, starches (e.g., amylose and amylopectin), hydrophilic celluloses and carboxymethyl, methyl, hydroxyethyl and hydroxypropyl derivatives thereof (e.g., hydroxyethyl cellulose, hydroxypropyl methylcellulose, hydroxypropyl cellulose, carboxymethyl cellulose, methyl cellulose), pullulan, dextrin, or combinations thereof. In some examples, the protective colloid consists of maltodextrin. The maltodextrin may have the DE, molecular weight, and water solubility described above. In some examples, the protective colloid comprises maltodextrin having a molecular weight of 10,000Da or less. The dispersible copolymer powder can include 1 wt% or more (e.g., 2 wt% or more, 3 wt% or more, 4 wt% or more, 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, or 20 wt% or more) of the protective colloid based on the total weight of the core polymer and the protective colloid polymer. In some examples, the dispersible copolymer powder can include 40 wt% or less (e.g., 35 wt% or less, 30 wt% or less, 25 wt% or less, 20 wt% or less, 15 wt% or less, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, or 5 wt% or less) of the protective colloid, based on the total weight of the core polymer and the protective colloid polymer. The amount of protective colloid polymer in the dispersible copolymer powder can range from any of the minimum values described above to any of the maximum values described above. For example, the dispersible copolymer powder can include from 1 wt% to 40 wt% (e.g., from 2 wt% to 40 wt%, from 5 wt% to 25 wt%, from 5 wt% to 20 wt%, from 5 wt% to 15 wt%, from 10 wt% to 30 wt%, from 10 wt% to 25 wt%, or from 7 wt% to 25 wt%) of the protective colloid, based on the total weight of the core polymer and the protective colloid polymer. The weight ratio between the core polymer and the protective colloid polymer in the dispersible copolymer powder may be 1:1 or more. For example, the weight ratio between the core polymer and the protective colloid polymer may be 2:1 or greater, 3:1 or greater, 4:1 or greater, 5:1 or greater, 6:1 or greater, 7:1 or greater, 8:1 or greater, 9:1 or greater, 10:1 or greater, 12:1 or greater, 15:1 or greater, or 20:1 or greater. In some embodiments, the weight ratio between the core polymer and the protective colloid polymer may be 20:1 or less, 18:1 or less, 15:1 or less, 12:1 or less, 10:1 or less, 8:1 or less, or 5:1 or less. The weight ratio between the core polymer and the protective colloid polymer can range from any of the minimum values described above to any of the maximum values described above. For example, the weight ratio between the core polymer and the protective colloid polymer may be 1:1 to 20:1, 2:1 to 15:1, 5:1 to 20:1, or 5:1 to 15: 1. In addition to the protective colloid, the shell of the dispersible copolymer powder may contain one or more additives. One or more of the additional of the shells may be selected from a defoamer, an anti-caking agent (also referred to herein as an anti-blocking agent), a surfactant, or a mixture thereof. Without wishing to be bound by theory, having a low TgE.g. Tg