The aim of this work is to find an alternative lubricating grease formulation that can be produced from renewable and biodegradable sources with minimal risks to human health and the environment.We used a castor oil a...The aim of this work is to find an alternative lubricating grease formulation that can be produced from renewable and biodegradable sources with minimal risks to human health and the environment.We used a castor oil and electrospun cellulose acetate propionate(CAp)as raw materials.We hypothesized that the acetyl and propionyl groups could provide an adequate chemical compatibility with the castor oil and that the electrospun nanostructures could enable improved physical stability by creating a variety of morphologies allowing the tailoring of the rheological and tribological properties of the resulting greases.The experimental results show that the use of electrospun CAp nanostructures can indeed yield physically stable formulations,even when used at low concentrations(3 wt%).The resulting dispersions went through structural transitions due to changes in the thickener morphologies and/or concentration,as shown by oscillatory rheology,oil holding capacity,tackiness,and lubrication performance in metal–metal contact.We found that the formulations,containing smooth or porous CAp nanofibers,at 5 wt%as a thickener,possess suitable rheological and tribological properties with a performance comparable to that of traditional lithium lubricating greases.展开更多
It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and t...It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and then the efficient dispersion in castor oil to achieve stable gel-like systems,is proposed in this work.Rheological properties and microstructure of these materials were determined by means of small amplitude oscillatory shear tests and viscous flow measurements and atomic force microscopy observations,respectively.Moreover,both standardized penetration tests and tribological assays,usually performed in the lubricant industry,were carried out to evaluate the performance characteristics as lubricating greases.Linear viscoelasticity functions are affected by the lignin/diisocyanate ratio and thickener concentration.The thermorheological response evidenced a softening temperature of around 105°C.The microstructure of these gel-like dispersions is composed of interconnected thin fibers,homogeneously distributed in castor oil.Moreover,the NCO-functionalized lignin gel-like dispersions studied show lower friction coefficients than traditional lubricating greases.展开更多
基金sponsored by MCIN/AEI/10.13039/501100011033“ERDF A way of making Europe”(grant PID2021-125637OB-I00)FEDER/Junta de Andalucía Programmes(grants PY20_00751 and UHU202029).
文摘The aim of this work is to find an alternative lubricating grease formulation that can be produced from renewable and biodegradable sources with minimal risks to human health and the environment.We used a castor oil and electrospun cellulose acetate propionate(CAp)as raw materials.We hypothesized that the acetyl and propionyl groups could provide an adequate chemical compatibility with the castor oil and that the electrospun nanostructures could enable improved physical stability by creating a variety of morphologies allowing the tailoring of the rheological and tribological properties of the resulting greases.The experimental results show that the use of electrospun CAp nanostructures can indeed yield physically stable formulations,even when used at low concentrations(3 wt%).The resulting dispersions went through structural transitions due to changes in the thickener morphologies and/or concentration,as shown by oscillatory rheology,oil holding capacity,tackiness,and lubrication performance in metal–metal contact.We found that the formulations,containing smooth or porous CAp nanofibers,at 5 wt%as a thickener,possess suitable rheological and tribological properties with a performance comparable to that of traditional lithium lubricating greases.
文摘It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and then the efficient dispersion in castor oil to achieve stable gel-like systems,is proposed in this work.Rheological properties and microstructure of these materials were determined by means of small amplitude oscillatory shear tests and viscous flow measurements and atomic force microscopy observations,respectively.Moreover,both standardized penetration tests and tribological assays,usually performed in the lubricant industry,were carried out to evaluate the performance characteristics as lubricating greases.Linear viscoelasticity functions are affected by the lignin/diisocyanate ratio and thickener concentration.The thermorheological response evidenced a softening temperature of around 105°C.The microstructure of these gel-like dispersions is composed of interconnected thin fibers,homogeneously distributed in castor oil.Moreover,the NCO-functionalized lignin gel-like dispersions studied show lower friction coefficients than traditional lubricating greases.
