Bacterial Cellulose Nanofibers as Reinforcement for Preparation of Bamboo Pulp Based Composite Paper

Bamboo fibers(BFs),with features of renewability and biodegradability,have been widely used in paper-making products.In order to improve the mechanical properties and water absorption behaviors of the BF paper,bacterial cellulose nanofibers(BCNFs)as environmentally friendly nano-fibrillated cellulose(NFC)were combined with BFs.The structures and properties of the BF/BCNF composite paper were characterized by field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),Fourier transforms infrared(FTIR)spectroscopy,mechanical tests,pore size tests,and water absorption tests.The results indicated that the addition of BCNFs could significantly improve the water absorption capacity and mechanical properties.The water absorption ratio of the BF/BCNF composite paper with a BCNF mass fraction of 9%comes to 443%,about 1.33 times that of the pure BF paper.At the same BCNF content,the tensile strength of the BF/BCNF composite paper in dry and wet states was 12.37 MPa and 200.9 kPa,respectively,increasing by 98.24%and 136.91%as compared with that of the BF paper.

Specific Ion Effects on the Enzymatic Degradation of Polyester Films

Soil environment on earth contains a variety of ions,which are expected to play a vital role in the biodegradation of plastics discarded in the environment.In this work,poly(butyleneadipate-co-terephthalate)(PBAT)is employed as a model biodegradable plastic to study the specific ion effects on the enzymatic degradation of polyester plastics.The results show that the specific ion effects on the enzymatic degradation rate of the PBAT films and on the catalytic rate constant for the enzymatic hydrolysis of the ester bonds are strongly dependent on temperature and ionic strength.Both the enzymatic degradation rate and catalytic rate constant decrease following the trends Na^(+)>K^(+)>Ca^(2+)and Cl^(-)>SO_(4)^(2-)>NO_(3)^(-)for cations and anions,respectively,indicating that the ion-specific enzymatic degradation of the PBAT films is closely correlated with the specific ion effects on enzymatic hydrolysis of the ester bonds.Our study shows that the specific ion effects on the enzyme activity can be understood by taking into account the ion-specific cation-anion interaction,ionic dispersion force,salting-out effect and salting-in effect.This study of specific ion effects on the enzymatic hydrolysis of the ester bonds and the resultant enzymatic degradation of the PBAT films would offer us a new clue to develop new biodegradable,environmentally friendly synthetic plastics.

Construction of dual crosslinked network binder via sequential ionic crosslinking for high-performance silicon anodes

Nowadays,silicon has become a promising anode active material for lithium-ion batteries due to its high specific capacity.However,traditional binder materials cannot effectively restrain the volume expansion of silicon during lithiation/delithiation.Inspired by the growth process of climbing plants,we sequentially crosslink sodium alginate with calcium ions and hyperbranched polyethyleneimine to construct a dual crosslinked network binder.During the sequentially crosslinking,sodium alginate preferentially crosslinks with Ca^(2+)to form the"trellis"network,which restricts the free movement of hyperbranched polyethyleneimine and guides it,like"vine",to gradually anchor on the surrounding"trellis"through hydrogen and ionic bonding.In this dual crosslinked network,the ionic ally crosslinked sodium alginate maintains the anode structural integrity;the anchored hyperbranched polyethyleneimine forms strong multidimensional hydrogen bonds with silicon nanoparticles through its amino-rich branch chains;and the network utilizes the bonding reversibility of hydrogen and ionic bonds to repeatedly eliminate the mechanical stress and self-heal the structure damages caused by the volume change of silicon.Benefited from the multifunction of the dual crosslinked network,the silicon anode has achieved an excellent electrochemical performance with a specific capacity of 2403 mAh·g^(-1)at the current density of500 mA·g^(-1)after 100 cycles.