Pure PVA Film Research Articles

Development of biocompatible packaging material: starch/PVA-based bio-composite enhanced with hydroxypropyl methylcellulose

ABSTRACT Hydroxypropyl methylcellulose (HPMC) incorporated bio-composite films (unplasticized and plasticized) were prepared from pregelatinized maize starch/polyvinyl alcohol (PMS/PVA) blends by solution casting method. 10% boric acid (BA) was used as crosslinker. The physico-mechanical properties (tensile strength (TS), elongation at break (%EB), water solubility and moisture uptake) of the bio-composite films were studied. The thermo-chemical stability of the biofilms was studied by FT-IR, TGA and DSC analysis. TS, %EB, water solubility and moisture absorbency of 10% HPMC containing unplasticized films were found 38.1 MPa, 8.5%, 61% and 32.3%, respectively, however, the films were hard and brittle. On the contrary, TS, %EB, water solubility and moisture absorbency of 10% HPMC plasticized films were found 19.2 MPa, 28.5%, 62.2% and 57.3%. The biofilms exhibited relatively low water solubility and moisture uptake compared to higher HPMC containing composite. The thermo-chemical analysis revealed that the HPMC incorporated plasticized film was more thermally stable compared to pure PMS, PVA, HPMC and other bio composite films due to strong hydrogen bonding interaction with BA. The biodegradability of HPMC incorporated plasticized films was confirmed by soil burial test (anaerobic condition, RH 98%, 3 months). Therefore, the plasticized biofilm would be considered an alternative approach for biocompatible packaging material.

Physical properties of rutile-TiO2 Nanoparticles and effect on PVA/SiO2 hybrid films synthesized by sol-gel method

We use an ab-initio approach to analyze the structural, electronic band structure, and thermoelectric properties of titanium dioxide (TiO2 in rutile phase), and we then use rutile-TiO2 nanoparticles to determine its effects on sol-gel-produced polyvinyl alcohol/silicon dioxide (PVA/SiO2) hybrid films. The synthesis of hybrid films involved the incorporation of 1 % rutile-TiO2 nanoparticles in the PVA/SiO2 matrix. The thermoelectric properties of the resulting hybrid films were characterized by Seebeck coefficient measurements, as well as electrical and thermal conductivities. The synthesis of PVA/SiO2/Nano-TiO2 films was accomplished with success. The chemical bonds have amply demonstrated that the PVA backbone is connected to the (SiO2-TiO2) network. TGA testing indicates that hybrid films are more resistant to higher temperatures than pure PVA films. SiO2 nanoparticles reveal more effective loading to improve dielectric characteristics compared to TiO2. The best results are obtained in cases of mechanical, thermal and electrical insulation when both nanofillers are integrated into the polymer matrix. The findings show that the thermoelectric performance of PVA/SiO2 hybrid films is improved by the addition of (1 %) rutile-TiO2 nanoparticles in the rutile phase. This study provides insights into the potential applications of rutile-TiO2 nanoparticles in enhancing the thermoelectric properties of hybrid materials and opens up avenues for further research in this area, and contributes to the growing body of knowledge on enhancing the thermoelectric properties of materials by incorporating rutile-TiO2 nanoparticles into hybrid films synthesized by the sol-gel method.

Investigating surface and wettability properties of Na2Ti3O7/Na2Ti6O13/PVA composites

ABSTRACTCeramics-polymer composites have garnered significant interest in recent years due to their unique combination of properties and potential applications. This study presents an in-depth analysis of the surface and wettability properties of new Na2Ti3O7/Na2Ti6O13/PVA composite, aiming to uncover their unique characteristics. The analysis revealed notable changes in the morphology and 3D spatial patterns of the films upon incorporating heated and unheated Na2Ti3O7/Na2Ti6O13 into the PVA matrix. The PVA film containing heated ceramics displayed hierarchical topographic roughness (3.71±1.13 nm) similar to those of pure PVA films (2.28±0.13 nm), contrasting with the film containing unheated ceramics (12.31±2 nm). The surface texture of all films exhibited comparable isotropies (without significant difference at a p-value = 0.05), indicating that their physical properties remained largely unaffected by the heat treatment imposed on the ceramics. The surface microtexture similarity between the PVA film and the one containing heated ceramics can be attributed to their comparable spatial complexity (FD = 2.41–2.44). Contact angle measurements further demonstrated similar surface wettability between pure PVA (54.5±1.4°) and PVA containing heated Na2Ti3O7/Na2Ti6O13 ceramics (58.6±2.6°), which can be attributed to the resemblances in their surface microtextures. These findings highlight the pivotal role of heat treatment in the formation of Na2Ti3O7/Na2Ti6O13/PVA composites with surface and wettability properties akin to those of pure PVA films. This research contributes to the understanding of composite materials and their potential for various applications, including anticorrosive coatings, sensor devices, and surface engineering.

Fabrication and Testing of Crop Waste Ceiba pentandra Shell Powder Reinforced Biodegradable Composite Films.

Ceiba pentandra shell powder (CPSP) biowaste is chosen as a biofiller combined with poly(vinyl alcohol) (PVA) as a matrix to make biofilms to increase the exploitation of biowaste materials and reduce the use of plastic materials. FTIR plots indicated no significant chemical reaction or formation of new functional groups during interaction between PVA and CPSP. XRD diffractograms showed that the crystallinity index (35.3, 38.6, 42.3, 46.4, and 48.5%) and crystalline size (18.14, 20.89, 23.23, 24.87, and 26.34 nm) of biofilms increased with CPSP loading (5-25 wt %). The PVA/CPSP films are thermally stable up to 322 °C. The peak highs of AFM images showed that the films' surface roughness gradually increased from 94.75 nm (5 wt % CPSP) to 320.17 nm (25 wt % CPSP). The FESEM micrographs clarify the homogeneous distribution of CPSP in the PVA matrix. Tensile strength and tensile modulus are noticeably increased by 26.32 and 37.92%, respectively, as a result of the loading of CPSP from 5 to 20 wt % in the PVA matrix. The PVA/CPSP films outperform pure PVA films in UV shielding (350-450 nm). The 59% weight loss of films was estimated during 60 days of burial. The fabricated biofilms maintained their suitable structural, thermal, morphological, and mechanical properties. Additionally, they exhibited consistent performance in ultraviolet (UV) barrier, opacity, water absorption, water vapor permeability, soil burial, and antimicrobial characteristics over time. Overall, PVA/CPSP (5-25 wt %) films are biodegradable and have promising applications as good packaging materials.

Ultraviolet blocking ability, antioxidant and antibacterial properties of newly prepared polyvinyl alcohol-nanocellulose‑silver nanoparticles-ChunJian peel extract composite film

In this work, nanocellulose (CNC) from waste water chestnut (WCT) shell was firstly used for preparing nanocomposite films, by using ChunJian peel extract (CJPE) as a green reducing agent to synthesize silver nanoparticles (AgNPs), and then loading them into polyvinyl alcohol-nanocellulose (PVA-CNC) matrix, a multifunctional nanocomposite material that could be used in food packaging was developed. The prepared films were tested for mechanical strength, barrier properties, thermal properties, antibacterial, antioxidant and biocompatibility through various characterizations. The PVA-CNC-AgNPs-CJPE film had good thermostability, mechanical strength, barrier properties, and biocompatibility. Compared with pure PVA film and PVA-CNC film, PVA-CNC-AgNPs-CJPE could shield over 95 % of the UVB (320–275 nm) spectrum and UVC (275–200 nm) spectrum and most of the UVA (400–320 nm). By disk diffusion analysis, the inhibition zones of PVA-CNC-AgNPs-CJPE film against E. coli, P. aeruginosa, S. aureus and E. faecalis were 22.3 mm, 25.0 mm, 22.0 mm and 19.3 mm, respectively. The milk antibacterial simulation test confirmed that PVA-CNC-AgNPs-CJPE film could effectively limit bacterial reproduction and prolong the shelf life of milk. PVA-CNC-AgNPs-CJPE film had excellent UV barrier properties, good antioxidant properties and high-efficiency antibacterial activity, which is expected to be widely used in sustainable nanocomposite food packaging.

Lignocellulose Nanofibers Enhanced Mechanical and UV-Blocking Properties of Polyvinyl Alcohol Films

Lignin-containing cellulose nanofibers (LCNFs) from bamboo were prepared by choline chloride–lactic acid solvent treatment at 110–130∘C in combination with ultrasonication. Effects of LCNFs dosages on UV-blocking property, mechanical property, thermal stability and water vapor barrier property of LCNFs/PVA composite film were determined by UV spectrophotometer, universal mechanical testing machine, thermogravimetric analysis and weightlessness method, respectively. The results indicated that PVA film composited 10% LCNFs obtained from 120∘C showed best properties. As compared to pure PVA film, the UV-blocking property of composite film increased from 30% to 53%. LCNFs addition enhanced mechanical properties, resulting increment of tensile strength from 42[Formula: see text]MPa to 81[Formula: see text]MPa and elongation at break from 3% to 9%, respectively. LCNFs also introduced 2.4 times increment of water vapor barrier property of PVA film. The LCNFs/PVA composite films not only have excellent thermal stability and mechanical properties but also have UV-resistance and water vapor barrier properties. It provides a new idea for replacing some petroleum-based packaging materials and also shows the great potential of LCNFs materials.

Preparation of an Aminated Lignin/Fe(III)/Polyvinyl Alcohol Film: A Packaging Material with UV Resistance and Slow-Release Function.

To reduce the usage of petroleum-based plastic products, a lignin-based film material named aminated lignin/Fe(III)/PVA was developed. The mixture of 8 g lignin, 12 mL diethylenetriamine, 200 mL NaOH solution (0.4 mol·L-1), and 8 mL formaldehyde was heated at 85 °C for 4 h; after the aminated lignin was impregnated in the Fe(NO3)3 solution, a mixture of 3 g aminated lignin/Fe(III), 7 g PVA, and 200 mL NaOH solution (pH 8) was heated at 85 °C for 60 min; after 2 mL of glycerin was added, the mixture was spread on a glass plate to obtain the aminated lignin/Fe(III)/PVA film. This film demonstrated hydrophobicity, an UV-blocking function, and a good slow-release performance. Due to the formation of hydrogen bonds between the hydroxyl groups of lignin and PVA, the tensile strength, the elongation at break, and the fracture resistance of the film were 9.1%, 107.8%, and 21.9% higher than that of pure PVA film, respectively. The iron content of aminated lignin/Fe(III)/PVA was 1.06 wt%, which mainly existed in a trivalent form. The aminated lignin/Fe(III)/PVA film has the potential to be used as a food packaging material with anti-ultraviolet light function and can also be developed as other packaging materials, such as seedling bowls, pots for transplanting, and coating films during transport.

Synthesis of lignin from waste leaves and its potential application for bread packaging: A waste valorization approach

In this study, lignin was synthesized from the waste leaves of Ficus auriculata obtained after the extraction of gallic acid. The synthesized lignin was incorporated into PVA films, and the neat and blended films were characterized using different techniques. Lignin addition improved the UV-shielding, thermal, antioxidant, and mechanical properties of PVA films. The water solubility decreased from 31.86 % to 7.14 ± 1.94 %, while the water vapor permeability increased from 3.85 ± 0.21 × 10−7 g.m.h−1 Pa−1 to 7.84 ± 0.64 × 10−7 g.m.h−1 Pa−1 for pure PVA film and the film containing 5 % lignin, respectively. The prepared films showed a much better performance than commercial packaging films in inhibiting mold growth during the storage of preservative-free bread. The bread samples packed with commercial packaging showed signs of mold growth on the 3rd day, while the growth was inhibited entirely till the 15th day for PVA film containing 1 % lignin. The pure PVA film and the ones containing 3 % and 5 % of lignin inhibited growth till the 12th and 9th day, respectively. Findings from the current study show that safe, cheap, and eco–friendly biomaterials can hinder the growth of spoilage microorganisms and potentially be used in food packaging.

Construction of composite films using carbon nanodots for blocking ultraviolet light from the Sun.

Carbon nanodots (CNDs) which demonstrate concentration-dependent emission and have a photoluminescence quantum yield of 45% were designed. Transparent CND-containing composite films (CND-films), obtained by combining the CNDs with polyvinyl alcohol in different proportions, were shown to block the UV component of sunlight. Whereas the pure PVA film could not block UV light, the ability of CND-films to block UV light could be adjusted by altering the proportion of CNDs in the film. The larger the proportion of CNDs, the greater the extent of UV blocking. CND-film containing 32 wt% CNDs completely blocked UV light (≤400 nm) from sunlight, without affecting the transmission of visible light (>800 nm). The ability of the CND-films to block the UV component of sunlight was investigated using a commercially available UV-induced color change card, which confirmed that the capacity of the CND-films to block UV light could be adjusted by altering the proportion of CNDs in the film. This study shows that CNDs with concentration-dependent long wavelength emission characteristics can be used as optical barrier units for the preparation of materials to block high-energy short wavelength light.

Structural, conductivity and dielectric studies of pure and KCL doped polymer electrolyte films

Using the solution cast method, poly (vinyl alcohol) complexed with KCl was used to make solid polymer electrolyte films. XRD was used to look at the structure of these films. The outcomes of the Powder × - ray diffraction show that the composite films had more noncrystalline phases of PVA matrix. An AC impedance spectroscopy suggested that the ionic conductivity mainly arisen from grain effect. Conductivity of pure PVA is found to be of the order of 10-8 S/cm. With the addition of 20 wt% of KCl, the conductivity is dropped to the order of 10-10 S/cm, and then increased with the addition of KCl. The increase in conductivity with dopant type is based on the ionic character of the dopant. Real part of Impedance (Z') and imaginary part of impedance (Z“) of pure PVA and various composite films with 20 wt% of KCl, additives with different weight ratios were measured as a function of frequency. Dielectric permittivity and dielectric loss of all PVA with KCl 20 wt% of Polymer films investigated as a function of frequency at a room temperature is studied.Different electrochemical applications can be developed using these kinds of solid electrolytes.

In vitro cell proliferation, adhesion studies, and enhancement of mechanical properties of organo solve-lignin functionalized halloysite clay nanotube fillers doped onto poly (vinyl alcohol) film

Novel surface-functionalized Lignin-rough.HNTs with favourable properties were synthesised using lignin (Lig.) and halloysite nanotubes (HNTs). The produced Lig-rHNTs reinforced onto Poly (vinyl alcohol) (PVA) matrix. Spectroscopic and morphological investigations showed surface functionalization of HNTs with lignin via hydrogen bonding. The lignin functionalized rough-HNTs (Lig-rHNTs) were investigated using FTIR, AFM, SEM, X-ray diffraction, thermal, mechanical, water contact angle (WCA), and swelling ratio analysis. WCA was used to measure film hydrophilicity and compared to swelling tests. Morphological investigations showed that increasing the amount of Lig-rHNTs in the films increased surface roughness. Mechanical and thermal qualities increased compared to pure PVA film. Nanocomposite films outperform pristine PVA films in proliferative and adhesion capacity and enzymatic breakdown. Furthermore, human erythrocyte testing showed that nanocomposite films are hemocompatible, indicating more excellent tissue engineering and wound healing potential.

Orange peel waste biorefinery in multi-component cascade approach: Polyphenolic compounds and nanocellulose for food packaging

This study proposed an efficient valorization of orange peel waste (OPW) thorugh a multi-product cascade biorefinery approach. In a first step, polyphenolic-rich bioactive extract was obtained using 100% ethanol after a suitability study of different solvent systems. Its use in ultrasound-assisted extraction at 80 °C also allowed obtaining bioactive extracts with higher characteristics and reducing the extraction time (30 min) compared to conventional extraction (5 h). The extractives free-OPW was then used to obtain nanocellulose with high yield (>70%), solely by subjecting the fiber to a high-pressure homogenization treatment without the need for additional pretreatments, highlighting the efficiency of the process. The different components obtained were used separately and together on poly(vinyl alcohol)-based (PVA) films to study the isolated and synergistic effect they contributed to the properties of the films. The optimum cellulose nanofibers (CNF) content was found to be 5%, at higher contents a tendency to clustering of the nanofibers in the matrix was observed. The addition of polyphenol-rich extracts conferred interesting bioactive properties of special interest for food packaging. The antioxidant properties of the films increased as the extract content in the formulation increased, reaching almost 100% for an extract content of 30%. Also, UV-light blocking capacity was increased reaching values of 100% for extract contents above 20%. The synergistic effect of the joint addition of CNF and polyphenols resulted in bioactive films with high UV-blocking capacity that maintained the structural and mechanical properties of pure PVA films. Regarding the antioxidant capacity, a more controlled release action is observed. These results evidenced that the synergistic effect between bioactive extracts and CNF could be an excellent enhancer of the active packaging.

Characterization of polyvinyl alcohol-nanocellulose composite film and its release effect on tetracycline hydrochloride

Desmodium intortum(Mill.) Urb. is an important source of organic fertilizers, but its utilization value has not been developed favorably. The utilization of polyvinyl alcohol is optimized, combined with the film-forming properties of polyvinyl alcohol, to prepare a high-quality composite film. When the nanocellulose content reached 0.8 %, the tensile stress reaches the maximum value, and the composite film is not easily torn. The addition of NCC reduces the crystallinity of the PVA component and increases the initial decomposition temperature of the alcohol-nanocellulose composite film. The thermal decomposition rate of the PVA/NCC composite film is slightly lower than that of the pure PVA film, indicating that the addition of NCC improves the heat resistance of the PVA film. The electron microscope results show that PVA has good compatibility with NCC. The release results of tetracycline hydrochloride showed that when the nanocellulose content reached 0.8 %, the loading rate reached 83.07 %. R2 value of the two materials is 0.99 under the zero-order model fitting, which suggest the release process is transported by Supercase-II transport kinetics. Through the inhibition zone and cytotoxicity, it is proved that this material has a certain bacteriostatic effect and good cytocompatibility.

Effects of an acidic catalyst on the barrier and water resistance properties of crosslinked poly (vinyl alcohol) and boric acid films

Although the high oxygen-barrier property of poly (vinyl alcohol) (PVA) makes it attractive for packaging applications, its complete valorization is hindered owing to its low water resistance and poor thermal properties. To overcome these drawbacks, boric acid (BA)-crosslinked PVA (BCPVA) films were prepared using the solution casting method in the presence of different amounts of HCl as the acidic crosslinking catalyst. The properties of the pure PVA film showed a strong dependence on the HCl content. The enhancement of the crosslinking density in the pure PVA film imparted hydrophobicity to the film; as a result, the water sorption was remarkably reduced and the water resistance was enhanced. The existence of numerous crosslinking units in the matrix of the BCPVA film led to a reduction in crystallinity, while improving the barrier properties owing to the formation of extensive diffusion pathways within the matrix. The pure PVA film showed an OTR of 5.51 cc/m2·day, which significantly decreased for the BCPVA films from 1.33 to 0.79 cc/m2·day. Higher concentrations of HCl lead to a reduction in transparency and the formation of crystalline-like residues. Overall, this study demonstrated that adding HCl remarkably increased the crosslinking reaction between PVA and BA in the films, which in turn improved their oxygen barrier and water resistance. Therefore, the as-prepared PVA films crosslinked with BA and HCl can be used as barrier materials for various packaging applications.

UV-shielding and strong poly(vinyl alcohol) composite films reinforced with zinc oxide@polydopamine core-shell nanoparticles

Zinc oxide@polydopamine (ZnO@PDA) core-shell nanoparticles (NPs) were prepared by depositing PDA on the surface of ZnO NPs via the self-polymerization of dopamine (DA) in alkaline solution. It was found that ZnO@PDA exhibits lower photocatalytic activity and higher UV absorbance than pure ZnO. Moreover, ZnO@PDA NPs could be homogenously dispersed in poly(vinyl alcohol) (PVA) matrix and form strong hydrogen bonding interaction with PVA molecular chains. As a result, the prepared PVA/ZnO@PDA composite films display excellent UV-shielding, mechanical and anti-UV aging properties. Particularly, the PVA composite film added with 2.0 wt% ZnO@PDA is able to shield 96.1% UV irradiation (200–400 nm) and exhibits superior tensile strength (66.3 Mpa) than pure PVA film. Moreover, the result of UV aging tests indicate that ZnO@PDA also give a positive effect on the UV stability of PVA matrix, while PVA/ZnO composite film shows serious degradation. This work proposed a facile and rational strategy to design the ZnO-based UV-shielding agent with reduced photocatalytic activity and enhanced UV absorbance, which may provide an inspiration to construct high performance UV-shielding composites.

Investigation of physico‐mechanical, thermal, morphological, optical and biodegradation properties of polyvinyl alcohol films reinforced with alkali treated Limonia acidissima shell powder

AbstractPolyvinyl alcohol (PVA) and various concentrations of (5–25 wt%) alkali treated Limonia acidissima shell powder (LASP) was utilized to develop bio composite packaging films by solution casting method. The alkali treatment (5%NaOH) of the LASP particles were carried out to improve the interface adhesion between filler and PVA matrix and also remove non cellulosic contents from LASP. The biofilms were characterized by Fourier‐transform infrared spectroscopy, X‐ray diffraction analysis, thermogravimetric analyzer, field emission scanning electron microscopy, Tensile test, UV–vis spectroscopy analysis, water uptake, water vapor permeability, and soil burial test. The bio composite films reinforced with alkali treated LASP particles and compatibilized matrix lead to notable increase in the mechanical, optical, and biodegradation properties when compared to the neat PVA film. The increase in thermal stability (13.49%) of (332.06°C) PVA/alkali‐treated LASP biofilm compared to that of pure PVA film (287.24°C). Tensile stress and young's modulus were enhanced to 57.03% and 83.35%, respectively, with the inclusion of alkali‐treated LASP (up to 20 wt%) in PVA film. Scanning electron microscope micrographs showed that, beyond the 20 wt% of the filler the irregularities emerged on the surface of the biofilms, consequently the mechanical and water barrier properties were diminished However, the PVA/alkali‐treated LASP biofilms absorb less water than pure PVA films. The increased water transport with in the films facilitated the biodegradation behavior (32.11% of weight loss in soil) of composite film. Hence the results suggested the composite films developed in the study to be an ideal material for packaging and cosmetics industries as well as adding the value to wood apple (Limonia acidissima) waste.

Effects of 1-hexyl-1-methylimidazolium iodide ionic liquid to poly(vinyl alcohol)–based solid polymer electrolyte

A solid polymer electrolyte (SPE) membrane has been fabricated using poly (vinyl alcohol) (PVA) as polymer host dissolved in deionized (DI) water. Lithium bis(oxalato) borate (LiBOB) electrolyte salt and 1-hexyl 1-methylimidazolium iodide (HMII) are incorporated into the membrane to contribute free ions, enhancing ionic conductivity. SPE was produced using the solution cast technique on Petri dishes. Then these slurries were dried at room temperature. The final product is a self-standing opaque membrane with visually homogenous surfaces. Further observation using FE-SEM revealed magnified images of membrane surfaces and cross-sections. Molecule interaction and crystallinity were observed using FT-IR and XRD. Impedance measured using EIS was used to calculate ionic conductivity. It was found that ionic conductivity of pure PVA film was 3.9×10-7 S/cm while ionic conductivity of SPE before and after ionic liquid addition was 4.77×10-7 S/cm and 2.66×10-6 S/cm.

A copper organic phosphonate functionalizing boron nitride nanosheet for PVA film with excellent flame retardancy and improved thermal conductive property

With the rapid development of fifth-generation (5G)communication, the polymeric films with satisfactory flame retardancy and high thermal conductivity have become one of the hot topics in academic research and commercial applications. Herein, novel copper ethylene diaminetetrakis-(methylene phosphonate) functionalizing boron nitride nanosheet (Cu-EDTMP@BNNNS) was prepared by in-situ self-assembly method for reduction in the fire hazards ofpoly (vinyl alcohol) (PVA) film, as well as the improvement on its thermal conductive and mechanical performances. The good dispersion of 1Cu-EDTMP@1BNNNS in PVA matrix results in a 41-fold enhancement in thermal conductivity (8.4 W m−1 K−1) of the 1Cu-EDTMP@1BNNNS/PVA composite film compared to pure PVA film. In addition, the peak heat release rate and total heat release of the PVA composite film are 87.0% and 84.3%, respectively lower than the ones of pure PVA film. Moreover, the as-prepared composite film also possesses good flexibility, and high tensile strength (116 MPa).

Antibacterial Activity of Biodegradable Plastic from Chromolaena odorata (Pokok Kapal Terbang) Leaves

The aim of this research project was to develop antimicrobial films from blends of C. odorata and PVA and test the films for microbial activity using broth dilution methods for Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria. The result shows that CO/PVA80 successfully inhibit the growth of target bacteria. In antibacterial activity analysis, CO/PVA80 showed 50% higher compare with pure PVA film, PVA100. Other than that, the high percentage of PVA in the blend films, the greater the thickness, Tensile Strength (TS) and Young’s Modulus (YM), while the Elongation Break (EB) of the prepared films decreased. The 0.5 mm CO/PVA80 film shows a good result in mechanical properties which is TS 6.55 MPa, YM 182 MPa and EB is 7.47%. A CO/PVA80 were show a smooth texture, lacked of macropore and good characteristic with a SEM analysis. These results suggest that CO/PVA80 films have good compatibility to form an antimicrobial film as a new material for medical application especially for wound healing.

Greatly improved thermal conductivity and electrical insulation for PVA composites via introducing functional carbon nitride nanosheets

Carbon nitride has captured much attention of researchers since it was discovered, while few studies have focused on exploring the thermal conduction applications. In this paper, carbon nitride nanosheets (CNNS) could be simultaneously functionalized during the process of exfoliation. FTIR tests proved that hydrogen bonds were constructed between PVA matrix and CNNS, at the same time, superior dispersion were also observed from SEM characterizations. In this case, significantly improved compatibility at the interfaces of them could be achieved without additional modifications. The maximum in-plane thermal conductivity of CNNS/PVA composites was enhanced to 2.7 W m−1 K−1 with low CNNS content (7.5 wt%), resulting in a sharp enhancement (785%) in comparison with that of pure PVA film (0.305 W m−1 K−1). More importantly, the as-prepared CNNS/PVA composite (at 7.5 wt% CNNS content) could even be comparable to traditional highly thermally conductive polymer composites (Graphene, Boron Nitride, Mxene, etc., were used as fillers) in terms of similar conditions. Meanwhile, the incorporation of 7.5 wt% CNNS PVA composites also showed excellent mechanical properties and electrical insulation, where the tensile strength, elongation at break, and volume resistivity reached up to 30.578 Mpa, 193.089%, 3.34 × 1011 Ω·cm respectively. These multifunctional features further indicate that CNNS/PVA composites possess the great potential for thermal management. Therefore, this work can provide effective references to prepare highly thermally conductive polymer composites by constructing in-situ functionalized CNNS, and expands its application as well.