Effects of <scp>L</scp>‐ and <scp>D‐</scp> form oligo(lactic acid)s grafted cellulose reinforcement on the thermal properties of poly(<scp>L</scp>‐lactic acid) composites

Cellulose diacetate (CDA) and triacetate (CTA) were derived from Egyptian cotton to fabricate reverse osmosis (RO) membranes. The Pphase inversion method was utilized for the production of CDA‐based membranes. Comprehensive characterization of these membranes involved structural, morphologial, and hydrophilic property analyses through techniques such as nuclear magnetic resonance (NMR), infrared spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. NMR spectra indicated a degree of substitution of 2.9 for CTA and 2 for CDA. The resulting RO membrane demonstrated a water flux of 6.1 L/m2·h and a salt rejection of 90.3%. Annealing led to an enhanced top layer with reduced defects and macrovoids in the support layer. Moreover, grafting the RO membranes with 15 wt% of 2‐acrylamidopropane‐2‐methyl sulphonic acid improved salt rejection to 96.2% and water flux to 8.7 L/m2.h. These findings underscore the significant performance enhancements achieved through both annealing and grafting processes in RO membranes.

Section: Resultsmentioning

confidence: 99%

Improving water desalination: Sustainable grafted cellulose acetate reverse osmosis membrane from Egyptian cotton

Zhang,

Morsy,

Kandil

et al. 2024

“…The third stage was conducted from 430 to 597°C with weight loss of 65.7% that was assigned to the cleavage of CC backbone of films 82 . In addition, this weight loss is associated with the depolymerization of PVP and to the degradation of the CS 17 . The weight percentage of carbonized residue for films of (PVP/CS/PCA)/(ZnO‐NPs‐0.)…”

Section: Resultsmentioning

confidence: 99%

“…This is due to their brittle properties. Therefore, they cannot be utilized in packaging applications 16–18 . To overcome this matter, plasticizers are utilized to change the polymer chain interactions, which cause the brittleness of these films 19 .…”

Section: Introductionmentioning

confidence: 99%

Development of (polyvinylpyrrolidone/chitsoan/citric acid)/(zinc oxide‐nanoparticles) bionanocomposite films and their applications in biodegradation and antimicrobial activity

Awadallah‐F,

Aboulfotouh,

Ali

et al. 2023

Biofilm and bionanocomposite films were synthesized from polyvinylpyrrolidone (PVP), chitosan (CS), citric acid (CA), and zinc oxide‐nanoparticles (ZnO‐NPs). Effects of gamma‐irradiation dose and ZnO‐NPs concentrations; 0, 0.1, 0.3, 0.6, 0.9, 1.2, and 1.5 (wt./wt.)% were studied. Biofilms and bionanocomposite films were characterized by Fourier transform infrared, Raman spectroscopy, transmission electron microscopy, thermal gravimetric analysis, X‐rays diffraction, energy dispersive X‐ray, and mechanical properties to identify structure of biofilm and bionanocomposite films. Swelling (g/g)% and gelation (g/g)% of biofilms were carried out at diverse compositions of PVP to CS of (1/1), (1/2), and (2/1) (v/v). Swelling (g/g)% results of (1/1), (1/2), and (2/1) (v/v) were 116, 110, and 126, respectively. Values of highest and lowest gelation (g/g)% of (1/2) and (2/1) (v/v) are 98.0 ± 1.8 and 85.0 ± 2.6, respectively at 30 kGy. Water vapor transmission rate was studied for films and exposed 3450 ± 4.1 and 185.8 ± 1.2 (kg/m2.day) for open bottle and (PVP/CS/PCA)/(ZnO‐NPs‐1.5), respectively. Values of water solubility (g/g)% were investigated and found 30.21 ± 1.3 and 15.4 ± 2.5 for (PVP/CS/PCA)/(ZnO‐NPs‐0) and (PVP/CS/PCA)/(ZnO‐NPs‐1.5), accordingly. Bionanocomposite films displayed a broad‐spectrum antimicrobial activity against Gram‐negative bacteria and Gram‐positive bacteria. (PVP/CS/PCA)/(ZnO‐NPs‐0.1) showed lowest inhibition zone; 4 ± 0.2, 9 ± 0.5, 19 ± 0.1, and 8 ± 0.3 (mm) compared with (PVP/CS/PCA)/(ZnO‐NPs‐1.5) of highest inhibition zone; 16 ± 0.5, 28 ± 0.2, 33 ± 0.6, and 18 ± 0.3 (mm) for Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus, respectively. Antimicrobial activity increased with increasing ZnO‐NPs concentrations. Biodegradation of biofilms and bionanocomposite films were examined under soil from 0 to120 days. Results of weight loss (g/g)% at 120 days of (PVP/CS/PCA)/(ZnO‐NPs‐0) and (PVP/CS/PCA)/(ZnO‐NPs‐1.5) are 72 ± 4.5 and 47.5 ± 3.8, respectively. Bionanocomposite films were used in food preservation of fresh cherry tomatoes for 30 days and showed goodness. Therefore, these results suggest that the possibility of using bionanocomposite films in food‐packaging applications.Highlights Synthesis of development of (polyvinylpyrrolidone/chitsoan/citric acid)/(zinc oxide‐nanoparticles) bionanocomposite films. Characterization of bionanocomposite films by different techniques. Study of biodegradation of bionanocomposite films. Study of antimicrobial of bionanocomposite films. Usage of bionanocomposite films in cherry tomatoes preservation for 30 days.

Study on the pyrolysis characteristics, kinetics, thermodynamics, volatile products, and chemical reactions of micron polyamide waste, a typical marine plastic microfragment

Liu,

Zheng,

et al. 2024

The pollution of waste plastic microfragments to the marine ecosystems is an increasingly serious problem. Pyrolysis is widely recognized as a viable technique for the treatment of such plastic waste materials. The pyrolysis behaviors, characteristic parameters, kinetics, thermodynamics, volatiles, and possible chemical reactions during the pyrolysis of micron polyamide waste (the main component of fishing gear abandoned in the marine environment) are studied in inert atmosphere in the present work. The results show that the pyrolysis of micron polyamide may be regarded as a one‐step reaction. The peak and average reaction rates decrease significantly when the heating rate increases. The calculated kinetic parameters can effectively predict the pyrolysis behaviors of micron polyamide. The pyrolysis of micron polyamide is characterized as an endothermic reaction that occurs non‐spontaneously. Furthermore, the information of volatiles was obtained. The volatiles with higher content were –CH2 groups, CO2, and lactam, and the volatiles with smaller content were: –NH groups, NH3, HCN, H2O, CO, and amide derivatives. In addition, an analysis was conducted to explore the potential chemical reactions.Highlights The pyrolysis of micron polyamide can be considered as a one‐step reaction. The obtained kinetic parameters can well predict the pyrolysis process. Pyrolysis of micron polyamide is a non‐spontaneous and endothermic reaction. Specific volatile products are determined by Fourier transform infrared and mass spectrometry. The chemical reactions that may occur during the pyrolysis have been inferred.