Physical properties of cellulose nanocrystal/magnesium oxide/chitosan transparent composite films for packaging applications.

Hitherto unreported hybrid nanofillers (CNC:MgO) reinforced chitosan (CTS) based composite (CNC:MgO)/CTS films were synthesized using a solution-casting blend technique and synergistic effect of hybrid nanofiller in terms of properties enhancement were investigated. Optical microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) technique, fourier-transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM) were used to characterize the films. The hybrid nanofiller considerably changed the transparency and color of the CTS films. The tensile strengths of (3 wt%) CNC/CTS, (3 wt%) MgO/CTS, (1:1)(CNC:MgO)/CTS, (1:2)(CNC:MgO)/CTS and (2:1)(CNC:MgO)/CTS films were 27.49 %, 35.60 %, 91.62 %, 38.22 %, and 29.32 % higher than pristine CTS films respectively, while the water vapor permeation were 28.21 %, 30.77 %, 34.62 %, 38.46 %, and 37.44 % lower than pristine CTS film, respectively. Moreover, the CTS composite films exhibited an improvement in overall water barrier properties after incorporating hybrid nanofillers. Our observations suggest that chitosan-based hybrid nanofiller composite films are a good replacement for plastic-based packaging materials within the food industry.

Dermatofibrosarcoma Protuberans: A Surgeon's Enigma.

Dermatofibrosarcoma protuberans (DFSP) is a soft-tissue tumor arising from the dermis. It is a rare tumor, but the important point is that it has a higher incidence of local recurrence than other tumors. Management is primarily by wide local excision (WLE) with tumor negative margin (R0 resection) or Mohs micrographic surgery (MMS). In our case, a 57-year-old male patient presented with an anterior abdominal wall ulcerated mass. The patient had undergone surgery for the excision of the mass, twice before, at a different health-care facility. An incisional biopsy of the mass done at our hospital revealed it to be DFSP. The patient was treated by WLE with flap reconstruction. Post-operative histopathology examination (HPE) report confirmed DFSP with tumor-free margins (R0 resection). So if we fail to diagnose and manage DFSP correctly from the other commonly occurring tumors in the initial stages, there are very high chances of recurrence, and this causes significant morbidity to the patients.

Three Cases of Appendiceal Mucocele: From Diagnosis to Management.

Appendiceal mucocele is an appendicular dilatation secondary to the intraluminal accumulation of mucous material. Adequate pre-operative diagnosis and surgical resection remains the standard management. Here, we present three cases of appendiceal mucocele. In the first case, a 60-year-old female presented with signs and symptoms of acute appendicitis and was admitted and operated. An inflamed distended globular cystic mass of appendix measuring 10 × 6 × 4 cm with a wide base was found and the patient underwent right hemicolectomy. In the second case, a 30-year-old male with symptoms and signs of acute appendicitis was admitted to the emergency department. An open surgery was performed and a distended, tense, and inflamed appendix without perforation of size 6 × 1 × 1 cm was discovered and removed. The diagnosis of mucocele appendix was suspected and confirmed by postoperative dissection of the specimen and histopathology. In the third case, a 25-year-old female patient was subjected to diagnostic laparoscopy in view of non-specific pain abdomen. A diagnosis of mucocele of appendix was made intraoperatively and removed using a specimen bag. Appendiceal mucocele with acute presentation is a rare pathology that clinically resembles acute appendicitis. Preoperative detailed investigations to reach a definitive diagnosis are critical for adequate surgical resection and overall outcome.

Synergistic Tribo-Activity of Nanohybrids of Zirconia/Cerium-Doped Zirconia Nanoparticles with Nano Lamellar Reduced Graphene Oxide and Molybdenum Disulfide.

Zirconia and 10%, 20%, and 30% cerium-doped zirconia nanoparticles (ZCO), ZCO-1, ZCO-2, and ZCO-3, respectively, were prepared using auto-combustion method. Binary nanohybrids, ZrO2@rGO and ZCO-2@rGO (rGO = reduced graphene oxide), and ternary nanohybrids, ZrO2@rGO@MoS2 and ZCO-2@rGO@MoS2, have been prepared with an anticipation of a fruitful synergic effect of rGO, MoS2, and cerium-doped zirconia on the tribo-activity. Tribo-activity of these additives in paraffin oil (PO) has been assessed by a four-ball lubricant tester at the optimized concentration, 0.125% w/v. The tribo-performance follows the order: ZCO-2@rGO@MoS2 > ZrO2@rGO@MoS2 > ZCO-2@rGO > ZrO2@rGO > MoS2 > ZrO2 > rGO > PO. The nanoparticles acting as spacers control restacking of the nanosheets provided structural augmentation while nanosheets, in turn, prevent agglomeration of the nanoparticles. Doped nanoparticles upgraded the activity by forming defects. Thus, the results acknowledge the synergic effect of cerium-doped zirconia and lamellar nanosheets of rGO and MoS2. There is noncovalent interaction among all the individuals. Analysis of the morphological features of wear-track carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM) in PO and its formulations with various additives is consistent with the above sequence. The energy dispersive X-ray (EDX) spectrum of ZCO-2@rGO@MoS2 indicates the existence of zirconium, cerium, molybdenum, and sulfur on the wear-track, confirming, thereby, the active role played by these elements during tribofilm formation. The X-ray photoelectron spectroscopy (XPS) studies of worn surface reveal that the tribofilm is made up of rGO, zirconia, ceria, and MoS2 along with Fe2O3, MoO3, and SO42- as the outcome of the tribo-chemical reaction.

Dielectric Relaxation Behavior of Silver Nanoparticles and Graphene Oxide Embedded Poly(vinyl alcohol) Nanocomposite Film: An Effect of Ionic Liquid and Temperature.

This paper presents the dielectric characteristics of nanocomposite films of poly(vinyl alcohol) (PVA) embedded with silver (Ag) nanoparticles and graphene oxide(GO). The nanocomposite films were fabricated by using the solvent casting approach. The morphological analysis was carried out through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The dielectric relaxation behavior of nanocomposite films was analyzed in the frequency range of 101 to 106 Hz, by varying GO loading. The temperature effect was investigated over the temperature range of 40 to 150 °C. The effect of ionic liquid (IL) was also explored by comparing the dielectric behavior of films fabricated without using ionic liquid. The conductive filler loading variation showed a significant effect on dielectric permittivity(ε'), complex impedance (Z*) and electric conductivity (σac). The obtained results revealed that the dielectric permittivity (ε') increased by incorporating Ag nanoparticles and increasing GO loading in PVA matrix. An incremental trend in dielectric permittivity was observed on increasing the temperature, which is attributed to tunneling and hopping mechanism. With an increase in nanofiller loading, the real part of impedance (Z') and imaginary part of impedance (Z'') were found to decrease. Further, the semicircular nature of Nyquist plot indicated the decrease in bulk resistivity on increasing GO loading, temperature and incorporating ionic liquid. On the basis of above findings, the obtained GO-Ag-PVA nanocomposite films can find promising applications in charge storage devices.

Cellulose Nanocrystal Reinforced Chitosan Based UV Barrier Composite Films for Sustainable Packaging.

In this study, green composite films based on cellulose nanocrystal/chitosan (CNC/CS) were fabricated by solution casting. FTIR, XRD, SEM, and TEM characterizations were conducted to determine the structure and morphology of the prepared films. The addition of only 4 wt.% CNC in the CS film improved the tensile strength and Young's modulus by up to 39% and 78%, respectively. Depending on CNC content, the moisture absorption decreased by 34.1-24.2% and the water solubility decreased by 35.7-26.5% for the composite films compared with neat CS film. The water vapor permeation decreased from 3.83 × 10-11 to 2.41 × 10-11 gm-1 s-1Pa-1 in the CS-based films loaded with (0-8 wt.%) CNC. The water and UV barrier properties of the composite films showed better performance than those of neat CS film. Results suggested that CNC/CS nanocomposite films can be used as a sustainable packaging material in the food industry.

Polyamide 6/Poly(vinylidene fluoride) Blend-Based Nanocomposites with Enhanced Rigidity: Selective Localization of Carbon Nanotube and Organoclay.

Polyamide 6 (PA6)/poly(vinylidene fluoride) (PVDF) blend-based nanocomposites were successfully prepared using a twin screw extruder. Carbon nanotube (CNT) and organo-montmorillonite (30B) were used individually and simultaneously as reinforcing nanofillers for the immiscible PA6/PVDF blend. Scanning electron micrographs showed that adding 30B reduced the dispersed domain size of PVDF in the blend, and CNT played a vital role in the formation of a quasi-co-continuous PA6-PVDF morphology. Transmission electron microscopy observation revealed that both fillers were mainly located in the PA6 matrix phase. X-ray diffraction patterns showed that the presence of 30B facilitated the formation of γ-form PA6 crystals in the composites. Differential scanning calorimetry results indicated that the crystallization temperature of PA6 increased after adding CNT into the blend. The inclusion of 30B retarded PA6 nucleation (γ-form crystals growth) upon crystallization. The Young's and flexural moduli of the blend increased after adding CNT and/or 30B. 30B exhibited higher enhancing efficiency compared with CNT. The composite with 2 phr 30B exhibited 21% higher Young's modulus than the blend. Measurements of the rheological properties confirmed the development of a pseudo-network structure in the CNT-loaded composites. Double percolation morphology in the PA6/PVDF blend was achieved with the addition of CNT.

Fabrication of Cellulose Nanocrystal/Silver/Alginate Bionanocomposite Films with Enhanced Mechanical and Barrier Properties for Food Packaging Application.

Eco-friendly cellulose nanocrystal/silver/alginate (CNC/Ag/Alg) bionanocomposite films were successfully prepared by blending of CNC with Ag/Alg solution. The CNC was fabricated from cellulose microcrystal (CMC) by acid hydrolysis method. The Ag nanoparticles (AgNPs) were generated by using Alg as a reducing agent through hydrothermal process. AgNPs-included composite films showed characteristic plasmonic effect of the AgNPs with the maximum absorption at 491 nm and they also showed high ultraviolet (UV) barrier properties. The CNC/Ag/Alg composite films were analyzed by using scanning electron microscopy, transmission electron microscopy, optical microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction technique. Depending on the type of nanofillers, tensile strength of the composite films increased by 39-57% and water vapor permeation decreased by 17-36% compared with those of the neat Alg films. The Ag/Alg and CNC/Ag/Alg films showed brown color as detected from the increase of both 'b' and 'a' parameters by colorimeter. The UV and water barrier properties of Alg based composite films were found higher than the Alg films. The obtained results suggested that the prepared composite films can be used in food packaging applications.

Graphene Nanoplatelet-Reinforced Poly(vinylidene fluoride)/High Density Polyethylene Blend-Based Nanocomposites with Enhanced Thermal and Electrical Properties.

In this study, a graphene nanoplatelet (GNP) was used as a reinforcing filler to prepare poly(vinylidene fluoride) (PVDF)/high density polyethylene (HDPE) blend-based nanocomposites through a melt mixing method. Scanning electron microscopy confirmed that the GNP was mainly distributed within the PVDF matrix phase. X-ray diffraction analysis showed that PVDF and HDPE retained their crystal structure in the blend and composites. Thermogravimetric analysis showed that the addition of GNP enhanced the thermal stability of the blend, which was more evident in a nitrogen environment than in an air environment. Differential scanning calorimetry results showed that GNP facilitated the nucleation of PVDF and HDPE in the composites upon crystallization. The activation energy for non-isothermal crystallization of PVDF increased with increasing GNP loading in the composites. The Avrami n values ranged from 1.9⁻3.8 for isothermal crystallization of PVDF in different samples. The Young's and flexural moduli of the blend improved by more than 20% at 2 phr GNP loading in the composites. The measured rheological properties confirmed the formation of a pseudo-network structure of GNP-PVDF in the composites. The electrical resistivity of the blend reduced by three orders at a 3-phr GNP loading. The PVDF/HDPE blend and composites showed interesting application prospects for electromechanical devices and capacitors.

Cellulose nanocrystals reinforced κ-carrageenan based UV resistant transparent bionanocomposite films for sustainable packaging applications.

In this work, κ-carrageenan bionanocomposite films were prepared by solution casting of a mixture of κ-carrageenan, glycerol, and various amounts of cellulose nanocrystals (CNCs, 0-9 wt.%). The structure and morphology of the bionanocomposite films were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Compared with κ-carrageenan films, the κ-carrageenan bionanocomposite films showed better mechanical and barrier properties (water and UV) and thermal stability. The water contact angle increased from 23.30° to 71.80° and the water vapor permeation decreased from 8.93 gm-1 s-1 Pa-1 to 4.69 × 10-11 gm-1 s-1 Pa-1 in the κ-carrageenan films loaded with 9-7 wt.% CNCs, respectively. The tensile strength and elongation at break of the films increased from 38.33 ± 3.79 MPa to 52.73 ± 0.70 MPa and from 21.50 ± 3.72% to 28.27 ± 2.39%, respectively, after CNC loading increased from 0 wt.% to 7.0 wt.%. These results indicated that the κ-carrageenan nanocomposite films have potential applications in food packaging.

Montmorillonite/graphene oxide/chitosan composite: Synthesis, characterization and properties.

The present work reports the successful preparation, thermal and mechanical characterization of high performance films of Na(+) montmorillonite (MMT)/graphene oxide (GO)/chitosan (CS) composite using simple solution mixing evaporation method. The formations of films were verified by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The thermal stability and mechanical properties of these films were investigated by thermogravimetric analysis (TGA) and mechanical testing (Instron 8871). The results obtained from these studies revealed that the composites of chitosan, MMT, and graphene oxide were homogeneous in nature. A synergistic effect of MMT and GO reinforcing on chitosan matrix was observed for the first time, in case of 5 wt.% MMT and 1 wt.% GO. The tensile strength of (5 wt.%) MMT/(1 wt.%) GO/CS composite was formed 9±0.23% and 27±0.25% higher than that of the (1 wt.%) GO/CS composite and chitosan, respectively.

Synthesis and characterization of iron oxide/cellulose nanocomposite film.

Iron oxide/cellulose high-performance nanocomposite film is successfully prepared by impregnation of iron oxide nanoparticles into a regenerated cellulose film. The structure, thermal stability and mechanical properties of the nanocomposite films are investigated by the wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and mechanical pull test. The investigation results reveal that the iron oxide is bound to hydroxyl groups of the regenerated cellulose film by hydrogen bonding. Compared with the regenerated cellulose, the tensile strength and elastic modulus of iron oxide/cellulose high-performance films are significantly improved by about 39% and 57%, respectively.

Studies on graft copolymerization of gellan gum with N,N-dimethylacrylamide by the redox system.

The present paper reports the graft copolymerization of N,N-dimethylacrylamide onto gellan gumby free radical polymerization using potassium peroxymonosulphate/sarbose redox system in an inert atmosphere. The reaction conditions for maximum grafting have been optimized by varying the reaction variables, including the concentration of N,N-dimethylacrylamide(4.0×10(-2)-20×10(-2) mol dm(-3)), potassium peroxymonosulphate (0.6×10(-2)-1.4×10(-2)mol dm(-3)), sarbose (0.4×10(-3)-3.6×10(-3) mol dm(-3)), sulphuric acid (2.0×10(-3)-10×10(-3) mol dm(-3)), gellan gum (0.6-1.4 g dm(-3)) along with time duration (60-180 min) and temperature (25-45°C).Water-swelling capacity, metal ion sorption and flocculation studies of synthesized graft copolymer have been performed with respect to the parent polymer. The graft copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis.

Synthesis and characterization of graphene oxide/carboxymethylcellulose/alginate composite blend films.

In this work, graphene oxide/carboxymethylcellulose/alginate (GO/CMC/Alg) composite blends were prepared by a simple solution mixing-evaporation method. The resulting structure, thermal stability, and mechanical properties of the blends were investigated by wide-angle X-ray diffractometry, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, thermogravimetric analysis, and mechanical testing. The obtained findings revealed that CMC, Alg, and graphene oxide were able to form a homogeneous mixture. When compared to a CMC/Alg blend, the incorporation of 1 wt% graphene oxide improved the tensile strength and Young's modulus by 40% and 1128%, respectively. In addition, the GO/CMC/Alg composite blend film showed a higher storage modulus than the CMC/Alg blend.

Grafting of N-(hydroxymethyl) acrylamide on to κ-carrageenan: synthesis, characterization and applications.

The synthesis of graft copolymer [κ-carrageenan-g-N-(hydroxymethyl) acrylamide] is carried out in nitrogen atmosphere using potassium peroxymonosulphate (PMS) and glycolic acid (GA) as redox system. The effect of reaction variables including the concentration of N-(hydroxymethyl) acrylamide (4 × 10(-2) to 36 × 10(-2))mol dm(-3), PMS (4 × 10(-3) to 20 × 10(-3))mol dm(-3), GA (1.6 × 10(-3) to 4.8 × 10(-3)) mol dm(-3), sulphuric acid (4 × 10(-3) to 12 × 10(-3)) mol dm(-3), κ-carrageenan (0.6-1.8) g dm(-3) as well as time duration (60-180)min and temperature (25-45)°C has been studied. The physicochemical properties of graft copolymer synthesized have been performed in terms of water swelling, metal ion sorption and flocculation with respect to the κ-carrageenan as a parent polymer. The graft copolymer has been characterized by FTIR and thermogravimetic analysis.

Guar gum-g-N,N'-dimethylacrylamide: synthesis, characterization and applications.

The graft copolymerization of N,N'-dimethylacrylamide onto guar gum initiated by potassium peroxymonosulphate/glycolic acid redox pair in an aqueous medium was studied gravimetrically under a nitrogen atmosphere. Grafting ratio, grafting efficiency and add on increase on increasing the concentration of potassium peroxymonosulphate (8.0 × 10(-3) to 24.0 × 10(-3) mol dm(-3)) and glycolic acid concentration (4.4 × 10(-3) to 7.6 × 10(-3) mol dm(-3)). On increasing the hydrogen ion concentration from 4 × 10(-3) to 12.0 × 10(-3) mol dm(-3), grafting ratio, efficiency, add on and conversion were increased. Maximum grafting was obtained when guar gum and N,N'-dimethylacrylamide concentration were 1.0 × 10(-2) g dm(-3) and 14.0 × 10(-2) mol dm(-3), respectively. An increase in temperature from 25 °C to 45 °C, the grafting ratio increases but conversion and homopolymer decrease. The optimum time period for graft copolymerization was 2h. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis.

Graft (partially carboxymethylated guar gum-g-poly vinyl sulfonic acid) copolymer: from synthesis to applications.

The aim of the paper is to study the physico-chemical phenomenon of synthesized graft copolymer (carboxymethylated guar gum-g-vinylsulfonic acid). The reaction optimum conditions for grafting has also been determined by studying the effect of vinylsulfonic acid, hydrogen ion, peroxymonosulphate, glycolic acid concentration and carboxymethylated guar gum along with time and temperature. Experimental results show that maximum grafting has been obtained at 1.8 g dm(-3) concentration of partially carboxymethylated guar gum and 5.3 × 10(-2) mol dm(-3) concentration of vinylsulfonic acid. It has been observed that grafting ratio, add on, conversion, efficiency increase up to 4.0 × 10(-3) mol dm(-3) of hydrogen ion, 4 × 10(-3) mol dm(-3) of glycolic acid, 14 × 10(-3) mol dm(-3) of peroxymonosulphate and 35 °C of temperature. Grafted copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling, flocculating, metal ion uptake and resistance to biodegradability properties of partially carboxymethylated guar gum-g-vinylsulfonic acid have been determined.

Synthesis of partially hydrolyzed graft copolymer (H-Ipomoea hederacea seed gum-g-polyacrylonitrile).

Polyacrylonitrile was grafted to Ipomoea hederacea (Ih) seed gum with 138.5% grafting yield and 43.55% grafting efficiency in a procedure that was performed under homogeneous microwave (MW) irradiation conditions for 70s in the absence of a radical initiator. Under similar conditions, a maximum grafting yield of 108% and 33.96% efficiency was achieved when the K2S2O8/ascorbic acid redox system was used as a radical initiator in a thermostatic water bath at 35 °C. The effects of reaction variables, such as monomer/Ih seed gum concentration, MW power, and exposure time on the graft copolymerization were studied. The partially hydrolyzed graft copolymer (H-Ih-g-PAN) formed a loose, porous surface and improved the water absorbency of Ih seed gum. The swelling behavior of H-Ih-g-PAN in various ionic salt (NaCl, MgCl2 and Na2SO4) solutions was also systematically investigated. The graft copolymer was further characterized using FTIR, TGA, XRD, and SEM.

Synthesis and properties of a water soluble graft (chitosan-g-2-acrylamidoglycolic acid) copolymer.

The present paper reports the graft copolymerization of 2-acrylamidoglycolic acid onto chitosan by using potassium bromate/silver nitrate as an efficient redox initiator in an inert atmosphere. The effect of reaction conditions on grafting parameters i.e. grafting ratio, efficiency, conversion, add on, homopolymer and rate of grafting has been studied. Experimental results show that maximum grafting has been obtained at 0.4 g dm(-3) concentration of chitosan, 8.0×10(-2) mol dm(-3) concentration of 2-acrylamidoglycolic acid and 1.0×10(-3) mol dm(-3) concentration of hydrogen ion. It has also been observed that grafting ratio, add on, conversion, efficiency and rate of grafting increase up to 3.2×10(-3) mol dm(-3) of silver nitrate and 1.7×10(-2) mol dm(-3) of potassium bromate. Time (120 min) and temperature (40°C) were kept constant during reaction. The physicochemical properties of graft copolymer synthesized have been performed in terms of water swelling, metal ion sorption, flocculation and resistance to biodegradability with respect to the chitosan as a parent polymer. The graft copolymer has been characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis.

Superabsorbent nanocomposite (alginate-g-PAMPS/MMT): synthesis, characterization and swelling behavior.

A superabsorbent composite (alginate-g-PAMPS/MMT) was prepared by graft copolymerization from alginate, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and Na+ montmorillonite (MMT) in an inert atmosphere. Effects of polymerization variables on water absorbency, including the content of Na+ montmorillonite, sodium alginate, N,N'-methylenebisacrylamide and AMPS, were studied. The introduced montmorillonite formed a loose and porous surface and improved the water absorbency of the alginate-g-PAMPS/MMT superabsorbent composite. Swelling behaviors of the superabsorbent composites in various cationic salt solutions (NaCl, CaCl2 and FeCl3) and anionic salt solutions (NaCl and Na2SO4) were also systematically investigated. The superabsorbent composite was further characterized using Fourier transform infrared spectroscopy (FTIR), rheology, thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) taking alginate-g-PAMPS as a reference.