Despite its biodegradability, adequate cohesive strength and comparatively low cost, the use of cooked starch as a paper coating binder is limited due to its high viscosity and serious negative impact on the gloss. St...Despite its biodegradability, adequate cohesive strength and comparatively low cost, the use of cooked starch as a paper coating binder is limited due to its high viscosity and serious negative impact on the gloss. Starch-based bio-latex with size in the nanometer or sub-micrometer range has been developed recently to overcome these shortcomings. In this study, ultrafine starch particle(UFSP) was prepared by mechanical milling using a DYNO mill in combination with light chemical pretreatment. Model coating colors containing different dosages of UFSP were applied to base paper and the properties of the coated papers were evaluated. The results showed that the UFSP was disc-shaped with a median particle diameter of 167 nm. Water retention capacity of the coating colors was improved considerably with the addition of UFSP, i.e., the water retention value decreased by nearly 40% when styrene-butadiene latex was replaced by UFSP at a dosage of 3 pph(per hundred parts of pigment). The high shear rate viscosities of the coating colors containing no more than 2 pph of USFP were similar to that of the control coating color at shear strain rate higher than 2000 s^(-1). The properties and performances of the coated papers were comparable to the control coated paper with single synthesized latex binder. The gloss and the print gloss of paper samples with or without USFP were 59.7% and 58.2%, 79.0% and 78.8%, respectively. Surface strength of paper samples with or without USFP were 0.96 and 0.90 m/s, respectively, while the ink absorptivity values were 34% and 33%. This study demonstrates a promising approach to obtain submicrometer sized starch for paper coating.展开更多
Food packaging is becoming popular as the consumption of ready-to-eat food products rises.Easyto-use,non-biodegradable plastic packaging is commonly used in food packaging,contributing to the deteriorating environment...Food packaging is becoming popular as the consumption of ready-to-eat food products rises.Easyto-use,non-biodegradable plastic packaging is commonly used in food packaging,contributing to the deteriorating environmental situation.This issue increases the concern for the environment and encourages the usage of alternative materials.Cellulose nanofibrils(CNF)are abundant and biodegradable,which makes them ideal candidates to replace plastic coatings.The ability to form H-bonds between the hydroxyl groups makes coated paper with CNF have good strength,but poor barrier properties.The barrier properties can be improved by grafting DMAEMA or HEMA onto CNF(CNF-g-PDMAEMA and CNF-g-PHEMA,respectively).Thus,the objective of this study was to modify CNF chemically to enhance the barrier properties of the food packaging paper.It was found that paper coated with CNFg-PDMAEMA and CNF-g-PHEMA exhibited improvements in mechanical and barrier properties while maintaining the desired viscosity for the coating process.The water contact angle increased for paper coated with CNF-g-PHEMA and CNF-g-PDMAEMA,reaching a maximum of 97.51°and 92.58°,respectively with the decreasing Cobb_(60) values by 49% and 11%.The oil absorption was also reduced for both coated papers compared to the blank paper.Mechanical properties improved,as indicated by a 3% increase in tensile strength for paper coated with CNF-g-PHEMA and a 5% for paper coated with CNF-g-PDMAEMA.The results indicated significant potential for the application of modified CNF in coatings for food packaging paper.Noteworthy,the grafting process should be improved to enhance the mechanical and barrier properties of the coated paper.展开更多
Recovering extracellular polymeric substances(EPS)from waste granular sludge offers a cost-effective and sustainable approach for transforming wastewater resources into industrially valuable products.Yet,the applicati...Recovering extracellular polymeric substances(EPS)from waste granular sludge offers a cost-effective and sustainable approach for transforming wastewater resources into industrially valuable products.Yet,the application potential of these EPS in real-world scenarios,particularly in paper manufacturing,remains underexplored.Here we show the feasibility of EPS-based biomaterials,derived from anaerobic granular sludges,as novel coating agents in paper production.We systematically characterised the rheological properties of various EPS-based suspensions.When applied as surface sizing agents,these EPS-based biomaterials formed a distinct,ultra-thin layer on paper,as evidenced by scanning electron microscopy.A comprehensive evaluation of water and oil penetration,along with barrier properties,revealed that EPS-enhanced coatings markedly diminished water absorption while significantly bolstering oil and grease resistance.Optimal performance was observed in EPS variants with elevated protein and hydrophobic contents,correlating with their superior rheological characteristics.The enhanced water-barrier and grease resistance of EPS-coated paper can be attributed to its non-porous,fine surface structure and the functional groups in EPS,particularly the high protein content and hydrophobic humic-like substances.This research marks the first demonstration of utilizing EPS from anaerobic granular sludge as paper-coating biomaterials,bridging a critical knowledge gap in the sustainable use of biopolymers in industrial applications.展开更多
This paper examined different kinds of organic functional groups that were introduced onto the surface of nano TiO_(2) by surface modification with different types of zircoaluminate coupling agents.The modified nanoTi...This paper examined different kinds of organic functional groups that were introduced onto the surface of nano TiO_(2) by surface modification with different types of zircoaluminate coupling agents.The modified nanoTiO_(2) products with different interfacial properties were obtained,and the impact of the interfacial properties of nanoTiO_(2) on the rheological behavior of paper coating and the properties of coated paper was systematically investigated.The steady shear rheological results showed that the paper coatings containing nano TiO_(2) exhibited a pseudoplastic fluid behavior,characterized as obvious shear thinning.Compared to the hydrophilic unmodified nano TiO_(2),modified nano TiO_(2) could contribute more to the viscosity of paper coatings.The study on the dynamic viscoelasticity revealed that,through the enhancing action among each component in paper coatings,the modified nano TiO_(2) with quaternary amine groups or carboxyl led to a higher dynamic elastic storage modulus and viscous loss modulus of paper coatings.In addition,SEM and AFM analyses indicated that adding modified nano TiO_(2) products in paper coating could improve the coating structure,thus ameliorating the optical properties and printability of coated paper.The results obtained could provide a good reference for the application of nano pigments in paper coating.展开更多
Drying of a coated paper is modeled and simulated.The paper sheet is assumed to form three zones,and each zone has its own drying mechanism.Coupling of energy and mass balances must be used in order to solve different...Drying of a coated paper is modeled and simulated.The paper sheet is assumed to form three zones,and each zone has its own drying mechanism.Coupling of energy and mass balances must be used in order to solve differential equations.The simulations are carried out in various drying conditions i.e.,only hot air drying,only radiant drying,and mixed hot air-radiant drying.Also the effect of one side and two side assumption on evaporation is studied.Effect of venting air speed and radiant heat source presence and its distance from the drying surface on the drying of a coated paper has been studied.It is found that both distance and venting air speed are inversely related to drying in mixed hot air-radiant drying.Both surfaces participate in evaporation however,during the last time of drying,no difference between the upper and the bottom surfaces exist.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.51403239)
文摘Despite its biodegradability, adequate cohesive strength and comparatively low cost, the use of cooked starch as a paper coating binder is limited due to its high viscosity and serious negative impact on the gloss. Starch-based bio-latex with size in the nanometer or sub-micrometer range has been developed recently to overcome these shortcomings. In this study, ultrafine starch particle(UFSP) was prepared by mechanical milling using a DYNO mill in combination with light chemical pretreatment. Model coating colors containing different dosages of UFSP were applied to base paper and the properties of the coated papers were evaluated. The results showed that the UFSP was disc-shaped with a median particle diameter of 167 nm. Water retention capacity of the coating colors was improved considerably with the addition of UFSP, i.e., the water retention value decreased by nearly 40% when styrene-butadiene latex was replaced by UFSP at a dosage of 3 pph(per hundred parts of pigment). The high shear rate viscosities of the coating colors containing no more than 2 pph of USFP were similar to that of the control coating color at shear strain rate higher than 2000 s^(-1). The properties and performances of the coated papers were comparable to the control coated paper with single synthesized latex binder. The gloss and the print gloss of paper samples with or without USFP were 59.7% and 58.2%, 79.0% and 78.8%, respectively. Surface strength of paper samples with or without USFP were 0.96 and 0.90 m/s, respectively, while the ink absorptivity values were 34% and 33%. This study demonstrates a promising approach to obtain submicrometer sized starch for paper coating.
基金supported by Hibah Penelitian Fundamental Reguler Kementerian Pendidikan,Kebudayaan,Riset dan Teknologi under funding year of 2024 with contract number:051/E5/PG.02.00.PL/2024NKB-903/UN2.RST/HKP.05.00/2024.
文摘Food packaging is becoming popular as the consumption of ready-to-eat food products rises.Easyto-use,non-biodegradable plastic packaging is commonly used in food packaging,contributing to the deteriorating environmental situation.This issue increases the concern for the environment and encourages the usage of alternative materials.Cellulose nanofibrils(CNF)are abundant and biodegradable,which makes them ideal candidates to replace plastic coatings.The ability to form H-bonds between the hydroxyl groups makes coated paper with CNF have good strength,but poor barrier properties.The barrier properties can be improved by grafting DMAEMA or HEMA onto CNF(CNF-g-PDMAEMA and CNF-g-PHEMA,respectively).Thus,the objective of this study was to modify CNF chemically to enhance the barrier properties of the food packaging paper.It was found that paper coated with CNFg-PDMAEMA and CNF-g-PHEMA exhibited improvements in mechanical and barrier properties while maintaining the desired viscosity for the coating process.The water contact angle increased for paper coated with CNF-g-PHEMA and CNF-g-PDMAEMA,reaching a maximum of 97.51°and 92.58°,respectively with the decreasing Cobb_(60) values by 49% and 11%.The oil absorption was also reduced for both coated papers compared to the blank paper.Mechanical properties improved,as indicated by a 3% increase in tensile strength for paper coated with CNF-g-PHEMA and a 5% for paper coated with CNF-g-PDMAEMA.The results indicated significant potential for the application of modified CNF in coatings for food packaging paper.Noteworthy,the grafting process should be improved to enhance the mechanical and barrier properties of the coated paper.
基金support from Guangdong Basic and Applied Basic Research Foundation,China(2023A1515010958,2022A1515110834,2023B1515040028)。
文摘Recovering extracellular polymeric substances(EPS)from waste granular sludge offers a cost-effective and sustainable approach for transforming wastewater resources into industrially valuable products.Yet,the application potential of these EPS in real-world scenarios,particularly in paper manufacturing,remains underexplored.Here we show the feasibility of EPS-based biomaterials,derived from anaerobic granular sludges,as novel coating agents in paper production.We systematically characterised the rheological properties of various EPS-based suspensions.When applied as surface sizing agents,these EPS-based biomaterials formed a distinct,ultra-thin layer on paper,as evidenced by scanning electron microscopy.A comprehensive evaluation of water and oil penetration,along with barrier properties,revealed that EPS-enhanced coatings markedly diminished water absorption while significantly bolstering oil and grease resistance.Optimal performance was observed in EPS variants with elevated protein and hydrophobic contents,correlating with their superior rheological characteristics.The enhanced water-barrier and grease resistance of EPS-coated paper can be attributed to its non-porous,fine surface structure and the functional groups in EPS,particularly the high protein content and hydrophobic humic-like substances.This research marks the first demonstration of utilizing EPS from anaerobic granular sludge as paper-coating biomaterials,bridging a critical knowledge gap in the sustainable use of biopolymers in industrial applications.
基金The authors extend a sincere acknowledge and appreciation for the financial support from the National Natural Science Foundation of China(Grant No.21306216,and Grant No.31470609)。
文摘This paper examined different kinds of organic functional groups that were introduced onto the surface of nano TiO_(2) by surface modification with different types of zircoaluminate coupling agents.The modified nanoTiO_(2) products with different interfacial properties were obtained,and the impact of the interfacial properties of nanoTiO_(2) on the rheological behavior of paper coating and the properties of coated paper was systematically investigated.The steady shear rheological results showed that the paper coatings containing nano TiO_(2) exhibited a pseudoplastic fluid behavior,characterized as obvious shear thinning.Compared to the hydrophilic unmodified nano TiO_(2),modified nano TiO_(2) could contribute more to the viscosity of paper coatings.The study on the dynamic viscoelasticity revealed that,through the enhancing action among each component in paper coatings,the modified nano TiO_(2) with quaternary amine groups or carboxyl led to a higher dynamic elastic storage modulus and viscous loss modulus of paper coatings.In addition,SEM and AFM analyses indicated that adding modified nano TiO_(2) products in paper coating could improve the coating structure,thus ameliorating the optical properties and printability of coated paper.The results obtained could provide a good reference for the application of nano pigments in paper coating.
文摘Drying of a coated paper is modeled and simulated.The paper sheet is assumed to form three zones,and each zone has its own drying mechanism.Coupling of energy and mass balances must be used in order to solve differential equations.The simulations are carried out in various drying conditions i.e.,only hot air drying,only radiant drying,and mixed hot air-radiant drying.Also the effect of one side and two side assumption on evaporation is studied.Effect of venting air speed and radiant heat source presence and its distance from the drying surface on the drying of a coated paper has been studied.It is found that both distance and venting air speed are inversely related to drying in mixed hot air-radiant drying.Both surfaces participate in evaporation however,during the last time of drying,no difference between the upper and the bottom surfaces exist.
