Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication,Characterization and Properties

In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.     

Poly(3-hydroxybutyrate)/ZnO Bionanocomposites with Improved Mechanical,Barrier and Antibacterial Properties

Poly(3-hydroxybutyrate) (PHB)-based bionanocomposites incorporating different contents of ZnO nanoparticles were prepared via solution casting technique. The nanoparticles were dispersed within the biopolymer without the need for surfactants or coupling agents. The morphology, thermal, mechanical, barrier, migration and antibacterial properties of the nanocomposites were investigated. The nanoparticles acted as nucleating agents, increasing the crystallization temperature and the degree of crystallinity of the matrix, and as mass transport barriers, hindering the diffusion of volatiles generated during the decomposition process, leading to higher thermal stability. The Young’s modulus, tensile and impact strength of the biopolymer were enhanced by up to 43%, 32% and 26%, respectively, due to the strong matrix-nanofiller interfacial adhesion attained via hydrogen bonding interactions, as revealed by the FT-IR spectra. Moreover, the nanocomposites exhibited reduced water uptake and superior gas and vapour barrier properties compared to neat PHB. They also showed antibacterial activity against both Gram-positive and Gram-negative bacteria, which was progressively improved upon increasing ZnO concentration. The migration levels of PHB/ZnO composites in both non-polar and polar simulants decreased with increasing nanoparticle content, and were well below the current legislative limits for food packaging materials. These biodegradable nanocomposites show great potential as an alternative to synthetic plastic packaging materials especially for use in food and beverage containers and disposable applications.     

Preparation and characterization of poly(vinyl alcohol) cryogel‐silver nanocomposites and evaluation of blood compatibility,cytotoxicity, and antimicrobial behaviors

In this investigation, cryogels composed of poly(vinyl alcohol) (PVA) were prepared by repeated freeze‐thaw method. The prepared cryogels served as templates for producing highly stable and uniformly distributed silver nanoparticles via in situ reduction of silver nitrate (AgNO₃) using alkaline formaldehyde solution as reducing agent. The structure of the PVA/Ag cryogel nanocomposites was characterized by a Fourier transform infrared and Raman spectroscopy. The morphologies of pure PVA cryogels and PVA/Ag nanocomposites were observed by a scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated Ag nanoparticles with diameter about 100 nm. XRD results showed all relevant Bragg's reflections for crystal structure of silver nanoparticles. The amount of silver in cryogel nanocomposites and thermal stability were determined by inductively coupled plasma atomic emission spectrometry (ICP‐AES) and thermogravimetric analysis measurements. Mechanical properties of nanocomposites were observed in terms of tensile strength. The antibacterial studies of the synthesized nanosilver containing cryogels showed good antibacterial activity against both gram‐negative and gram‐positive bacteria. The prepared PVA/Ag nanocomposites were also investigated for swelling and deswelling behaviors. The results reveal that both the swelling and deswelling process depends on the chemical composition of the cryogel silver nanocomposites, number of freeze‐Thaw cycles and pH and temperature of the swelling medium. The biocompatibility of the prepared nanocomposites was judged by in vitro methods of percent hemolysis and protein (BSA) adsorption. POLYM. COMPOS., 36:1983–1997, 2015. © 2014 Society of Plastics Engineer     

Insight on the influence of nano zinc oxide on the thermal,dynamic mechanical,and flow characteristics of Poly(lactic acid)– zinc oxide composites

Composites of Poly(lactic acid) (PLA) and spherical zinc oxide (ZnO) nanoparticles were prepared using melt processing followed by injection molding. The effect of nanosized ZnO on the molecular structure, thermal properties, dynamic mechanical properties, and flow characteristics of PLA composites were analyzed. Scanning electron microscopy images illustrated the formation of ZnO aggregates through PLA matrix. The molecular weight of PLA‐ZnO experienced a substantial decline by 55%, suggesting the presence of ZnO provoked degradation of PLA during composite preparation. Glass transition temperature of PLA‐ZnO decreased by 18% as compared with pure PLA, confirming the deleterious role of ZnO in PLA. The ZnO nanoparticles acted as a reactant and increased the thermal degradation rate. However, the incorporation of ZnO into PLA increased the crystallinity up to 20% and the storage modulus of composites in glassy state by 10%. The higher peak value of tan δ in composites suggested the more viscous behavior, which was further supported by lower number average molecular weight. The complex viscosity of composites exhibited a large Newtonian region over low shear rate, followed by shear thinning phenomenon. A significant decrease (96%) in complex viscosity was observed with the addition of ZnO into PLA. POLYM. ENG. SCI., 59:1242–1249 2019. © 2019 Society of Plastics Engineers     

Effect of a chain extender on the properties of poly(lactic acid)/zinc oxide/copper chlorophyll acid antibacterial nanocomposites

Poly(lactic acid) (PLA)/nano zinc oxide/copper chlorophyll acid (CCA) antibacterial nanocomposites with excellent mechanical properties were prepared in the presence of a chain extender named tolylene diisocyanate (TDI). The effect of the chain extender on the PLA long chain was confirmed by the increased molecular weight shown in the mass flow rate and gel permeation chromatography. Escherichia coli were adopted to examine the antibacterial ability of the blends. The effect of CCA is also discussed with regard to the enhancement of the antibacterial effect of zinc oxide (ZnO) over E. coli. Scanning electron microscopy and transmission electron microscopy were used to view the agglomeration and dispersion of ZnO in the PLA matrix. Differential scanning calorimetry and thermogravimetric analysis revealed a relatively stable thermal performance of the nanocomposites with and without TDI. A sharp increase in the mechanical properties was also observed after the addition of the chain extender under different processing conditions. Additionally, we found that the nanocomposites with the incorporation of TDI and the masterbatches in batches effectively improved the mechanical properties of PLA/ZnO/CCA without a sacrifice of the antibacterial effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41561.     

Poly lactic acid nanocomposites containing modified nanoclay with synergistic barrier to water vapor for coated paper

The binary nanocomposites of poly lactic acid (PLA) with the montmorillonite modified with trisilanol polyhedral oligomeric silsesquioxanes (Trisilanolisooctyl POSS^®) were prepared via a solution‐blending process and coated on paper by bar coating and compress hot melt coating methods. The resulting components were characterized with Fourier transform infrared spectroscopy, and X‐ray diffraction (XRD) techniques. Moreover, the water vapor transmission rates (WVTR) for the coated writing paper were determined using an IGA‐003. The results indicated that the modified clay PLA nanocomposites enhanced the water vapor barrier properties of coated paper significantly. The permeability of PLA nanocomposites to water vapor decreased by 74% [26.0 g/(m² day)], respectively, as compared to those of the paper coated with pure PLA. The dispersion and phase behavior of the modified montmorillonite in PLA matrix was revealed by Transmission electron microscope. The intercalation of montmorillonite with PLA was further demonstrated using XRD. WVTR results indicated that the compress hot melt coating of the nanocomposites is an effective method to improve the water vapor resistance of coated paper. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40952.     

Poly(vinyl alcohol) nanocomposite films: Thermooptical properties,morphology, and gas permeability

Poly(vinyl alcohol) (PVA)/saponite nanocomposites were prepared with various clay concentrations with the solution intercalation method. The intercalations of the polymer chains in the clay were examined with wide‐angle X‐ray diffraction and transmission electron microscopy. The variations of the dispersion, morphology, thermal properties, and gas permeability of the nanocomposites with clay concentrations in the range of 0–10 wt % were examined. Up to a 5 wt % clay loading, the clay particles were highly dispersed in the PVA matrix without any agglomeration of particles. However, some agglomerated structures formed in the polymer matrix above a 7 wt % clay concentration. The thermal stability of the hybrids increased linearly with increases in the clay loading up to 10 wt %. To measure the oxygen permeability and optical properties of the PVA hybrid films, the PVA hybrid solutions were coated onto both biaxially oriented polypropylene and poly(ethylene terephthalate) films, which were used as polymer substrates. The oxygen permeability values monotonically decreased with increases in the clay loading in the range of 0–10 wt %. The optical properties, such as the haze and gloss of the hybrid films when coated onto the matrix films, were nearly constant, that is, independent of the clay loading. These improvements arose because of the largely nanometer‐scale dispersion of the clay layers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 591–596, 2006     

Poly(vinyl alcohol) nanocomposites with sepiolite and heat‐treated sepiolites

Poly(vinyl alcohol) (PVA) nanocomposites with pristine sepiolite and heat‐treated (HT) sepiolites were prepared by the method of solution dispersion. The measurements of XRD, FTIR, TEM, and AFM were used for the characterization of the nanocomposites. Furthermore, thermal and optical properties were investigated by TG/DTG/DTA and UV‐visible transmission spectra, respectively. Both the effects of sepiolite/polymer ratio and the structural changes in sepiolite on heating were examined in terms of changes in the properties of the nanocomposites. The addition of sepiolite/HT sepiolites into the PVA matrix resulted in a decrease in the thermal decomposition temperatures of the nanocomposites because of the fact that sepiolite and HT sepiolites facilitated the elimination of the water and acetate groups from the PVA in the second step based on the TG/DTG studies. The HT sepiolites‐PVA nanocomposites had lower thermal stability and more influenced optical clarity than those of the sepiolite PVA, at the same filler levels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of highly emissive,thermally stable,UV‐cured polysilsesquioxane/ZnO nanoparticle composites

A high molecular weight polysilsesquioxane (LPMSQ)/ZnO nanocomposite was prepared by blending a methacryl‐substituted polysilsesquioxane and PMMA‐coated ZnO nanoparticle (NP) followed by UV‐curing process. These LPMSQ/ZnO nanocomposites gave high thermal and mechanical stabilities originated from the rigid ladder structured siloxane backbone of LPMSQ. The polysilsesquioxane and surface‐modified ZnO nanoparticles showed excellent compatibility between MMA groups in LPMSQ‐ and PMMA‐capped ZnO nanoparticles to give well‐dispersed LPMSQ/ZnO nanocomposites. Mechanically pliant and flexible free standing films were obtained, and the photo and optical properties of these hybrid nanocomposites were examined. The high photoluminescent properties were maintained even after severe thermal treatments exceeding 400°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42333.     

Improve the mechanical property and flame retardant efficiency of the composites of poly(lactic acid) and resorcinol di(phenyl phosphate) (RDP) with ZnO‐coated kenaf

The kenaf coated with zinc oxide (ZnO) was prepared and characterized by X‐ray diffraction, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The ZnO‐coated kenaf and the flame retardant resorcinol di(phenyl phosphate) were blended with poly(lactic acid) (PLA) by solution compounding and melt blending to prepare the flame‐retarded PLA composites. The thermal stability, the mechanical property, and the flame retardancy of the PLA composites were improved evidently. The tensile strength of the prepared PLA composites could reach up to 62.3 MPa in comparison with 55.4 MPa of the pure PLA. The dense and compact char residues were observed after the combustion of the PLA composites containing ZnO‐coated kenaf, whereas there were serious dripping phenomena and no char formation during the combustion of the pure PLA. The use of ZnO‐coated kenaf could increase flame retardant efficiency obviously. The mechanism of flame retardancy was discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

The influence of surface modification on the structure and properties of a zinc oxide‐filled poly(ethylene terephthalate)

Hydrophobic zinc oxide (ZnO) nanoparticles were successfully prepared by a one‐step precipitation reaction in an aqueous solution of zinc sulfate and sodium hydroxide with stearic acid as the modifying agent. Poly(ethylene terephthalate) (PET)/ZnO nanocomposites were prepared by further in situ polymerization of purified terephthalic acid, ethylene glycol and the ZnO nanoparticles. The surface modification of ZnO and the microstructure and properties of the nanocomposites were investigated using relative contact angle measurements, Fourier transform infrared spectroscopy, X‐ray diffraction, transmission and scanning electron microscopies, thermogravimetric analysis and differential scanning calorimetry. Measurements of relative contact angle indicated that the surface‐treated ZnO was hydrophobic. Compared to the nanocomposite filled with unmodified ZnO, a significant improvement in thermal stability and crystallinity was observed with the addition of 2 wt% surface‐treated ZnO. The experimental results also suggested that the properties of the nanocomposites were correlated with the dispersion of ZnO in PET and the interfacial interactions between ZnO and PET matrix. © 2012 Society of Chemical Industry     

Poly(lactic acid) and layered silicate nanocomposites prepared by melt mixing: Thermomechanical and morphological properties

Poly(lactic acid) (PLA) nanocomposites were prepared by melt mixing technique in a Haake batch mixer. The clay dispersion within the PLA matrix during melt mixing was well explained through the morphological characterization. Morphological characterizations were studied by X‐ray diffraction and transmission electron microscopy. The exfoliation/intercalation of the clay particles within the polymer matrix during melt mixing depends on the mixing torque generated during the preparation of nanocomposites. The significance of processing temperature and the mixing time in melt mixing were studied for PLA/C93A and PLA/C30B nanocomposites. The structure and properties of the nanocomposites were also characterized by differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and mechanical properties by standard tensile testing. The incorporation of nanoclays into the PLA matrix enhanced the mechanical properties and thermal stability of the PLA nanocomposites. This may be due to the reinforcing effect of nanoclays within the polymer matrix. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

滑石粉、氧化锌柱撑有机皂石复合填料对聚乳酸结晶及性能的影响

以改性滑石粉与氧化锌柱撑有机皂石为添加助剂,通过溶液插层法制备了聚乳酸基纳米复合材料。研究了该复合材料的微观结构、热性能及力学性能。结果表明,滑石粉层间距被增大,硅烷偶联剂（KH570）被有效包覆在滑石粉片层表面;添加0.3份氧化锌柱撑有机皂石时,聚乳酸复合材料的拉伸强度达到40.3MPa,比纯聚乳酸增加了约140.9%;改性滑石粉与氧化锌柱撑有机皂在聚乳酸基中起到了良好的异相成核作用,氧化锌柱撑有机皂石含量为0.3份时复合材料的结晶度与纯聚乳酸提高了87.0%,热分解温度提高了7.07oC。     

Synthesis of Novel (Polymer Blend-Ceramics) Nanocomposites: Structural,Optical and Electrical Properties for Humidity Sensors

Fabrication of novel nanocomposites films of (PVA–CMC) blend and (PVA–CMC) blend doped by niobium carbide nanoparticles has been investigated. The structural, optical and electrical properties of (PVA–CMC–NbC) nanocomposites for humidity sensors have been studied. The (PVA–CMC–NbC) nanocomposites were prepared with different concentrations of (polyvinyl alcohol and carboxyl methyl cellulose) and Niobium carbide nanoparticles. The experimental results of optical properties for (PVA–CMC–NbC) nanocomposites showed that the absorbance, absorption coefficient, extinction coefficient, refractive index, real and imaginary dielectric constants and optical conductivity of (PVA–CMC) blend increase with increase in Niobium carbide nanoparticles concentrations. The transmittance and energy band gap decrease with increase in Niobium carbide nanoparticles concentrations. The DC electrical properties of (PVA–CMC–NbC) nanocomposites showed that the electrical conductivity of the blend increases with increase in NbC nanoparticles concentrations. The experimental results of novel (PVA–CMC–NbC) nanocomposites applications showed that the (PVA–CMC–NbC) nanocomposites have high sensitivity for relative humidity.     

Studies of polylactide/zinc oxide nanocomposites: influence of surface treatment on zinc oxide antibacterial activities in textile nanocomposites

Polylactide (PLA)/zinc oxide (ZnO) nanocomposite filaments were produced with a melt‐spinning process, with the aim of obtaining antibacterial textiles. ZnO, an inorganic antibacterial nanofiller, is used to impart antibacterial properties to PLA. These nanoparticles suit the melt‐spinning process because of their high thermal stability and low granulometry. Generally, metallic oxides (e.g., ZnO) are used to recycle PLA via catalyzed unzipping depolymerization. In this study, we used different ways to finely disperse ZnO in PLA and produce filaments with a minimum degradation of the thermal and mechanical properties. Optimized antibacterial properties were obtained with a fabric containing ZnO with specific surface treatments. The reasons for this better antibacterial activity, related to the study of the antibacterial mechanism of ZnO, were investigated with different characterization techniques [X‐ray, electron probe microanalysis, inductively coupled plasma mass spectrometry, and electron paramagnetic resonance (EPR)]. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41776.     

Study on the Crystallization Kinetic and Characterization of Poly(lactic acid) and Poly(vinyl alcohol) Blends

In this study, poly(lactic acid) (PLA) and poly(vinyl alcohol) (PVA) blends, with PLA/PVA mass ratios of 100/0, 90/10, 80/20, 70/30, 60/40, 50/50, and 40/60, were prepared by means of the melt blending method. The result of torque measurements and thermal gravimtric analysis tests showed that the addition of PLA can decrease the melt viscosity of PVA and that the second degradation step of PVA nearly disappeared for the PLA₈₀/PVA₂₀ blend. The absorbance peaks of the carbonyl group and the hydroxyl group in the Fourier transform infrared spectra of PLA/PVA blends had significant shifts to lower wave numbers, indicating that there were interactions between these two groups. Combined with the result of the differential scanning calorimetry curves, this interaction would be favorable for improving miscibility. The X-ray diffraction patterns and the polarized light microscope (PLM) micrographs showed that PVA can serve as a nucleating agent to promote the crystallization of PLA in PLA/PVA blends. Moreover, the PLA₈₀/PVA₂₀ blend gave the highest growth rate of PLA spherulite.     

Synthesis of polyvinyl alcohol hydrogel grafted by modified Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles: characterization and doxorubicin delivery studies

During the last two decades, serious efforts have been directed towards the synthesis and coating magnetic nanoparticles for biomedical applications. Among many different types of polymeric coating materials that have been utilized in previous studies, we have selected polyvinyl alcohol (PVA). In this study, we report a novel type of magnetite nanocomposite-based PVA hydrogel. For this purpose, first, Fe₃O₄ nanoparticles were modified through hexamethylene diisocyanate (HMDI) and then PVA was modified by bromoacetyl bromide to produce bromoacetylated PVA. The modified PVA was cross-linked through various diamines such as ethylene-diamine, propylene-diamine and hexamethylenediamine. The prepared weak tridimensional PVA hydrogels were further reacted through unreacted hydroxyl groups with Fe₃O₄, modified by HMDI to form magnetite hard tridimensional hydrogels. The swelling behavior of the prepared magnetite nanocomposites were investigated and showed a fast initial swelling followed by a mild increase until attaining equilibrium. The structural, morphological, thermal and magnetic properties of the synthesized magnetite nanocomposites were confirmed by FTIR, thermal gravimetric analysis, vibrating sample magnetometer and scanning electron microscopy. The doxorubicin anti-tumor drug was loaded on a selected synthesized magnetic hydrogel and in vitro drug release studies were done in phosphate buffer solution in 37 °C.     

Thermal,thermomechanical, and morphological characterization of poly(vinyl chloride) (PVC)/ZnO nanocomposites: PVC molecular weight effect

Poly(vinyl chloride) (PVC)‐based nanocomposites containing 2 wt% zinc oxide (ZnO) nanoparticles were prepared by solution casting and the effect of the PVC molecular weight (MW) on the morphology, thermal properties, and thermogravimetric behavior was studied. The addition of ZnO nanoparticles to PVCs of different MWs increased the glass transition temperature (T_g) of the resulting nanocomposites, the extent of which was dependent upon the MW of the PVC matrix. The nanocomposite samples exhibited broadened transition zones as compared with their unfilled PVC matrices. The extent of transition zone broadening was also controlled by the MW of the PVC matrix in the nanocomposites. In the absence of ZnO nanoparticles, the increase in MW of PVC had no effect on the breadth of the transition zone. The TGA results showed that the incorporation of ZnO nanoparticles into PVC matrices of different MWs accelerated the first stage weight loss via the nanoparticle catalytic effect through removal of HCL from the polymeric chains. The presence of ZnO nanoparticles lowered the second stage weight loss, and the char yield obtained for nanocomposites samples was significantly greater than that obtained for neat PVC samples. At low MWs, the presence of ZnO nanoparticles had no effect on the first stage of thermal degradation process. The presence of ZnO nanoparticles in the matrix in different nanocomposites was revealed by SEM observations, and the EDX analysis demonstrated a progressive improvement in the distribution and dispersion state of ZnO nanoparticles in the PVC‐based nanocomposites as the MW of PVC matrix gradually increased. J. VINYL ADDIT. TECHNOL., 25:E63–E71, 2019. © 2018 Society of Plastics Engineers     

聚乙烯醇／蒙脱土复合材料的结构与性能研究

采用熔融插层法制备了聚乙烯醇(PVA)／蒙脱土(MMT)复合材料。通过X射线衍射仪和透射电镜对复合材料的结构进行表征，结果表明所得复合材料为剥离型或部分剥离型结构。热重测试、电子拉力试验和水溶性试验结果显示聚乙烯醇／蒙脱土纳米复合材料与纯聚乙烯醇相比，其加工热稳定性、综合力学性能以及耐水性能都得到了明显提高。     

The flame‐retardance polylactide nanocomposites with nano attapulgite coated by resorcinol bis(diphenyl phosphate)

The nano attapulgite (ATP) coated by flame‐retardant resorcinol bis(diphenyl phosphate) (RDP) was prepared, and the modification effects were analyzed by scanning electron microscopy plus energy dispersive spectrometer, Fourier‐transform infrared spectra, the contact angles, and thermal gravimetry analysis. The results showed that RDP was adsorbed and formed a uniform layer on the surface of nano ATP with a content of about 25 wt%. The prepared polylactide (PLA) nanocomposites with the RDP‐coated nano ATP showed good mechanical properties, and the tensile strength of the nanocomposites containing 30 wt% of the RDP‐coated nano ATP reached 76.9 MPa in comparison with 66.2 MPa of pure PLA. The limiting oxygen index of the prepared PLA composites containing 30 wt% of the RDP‐coated nano ATP was about 24.5% and V‐0 rating was attained compared with 20.5% and with no rating of pure PLA. After the burning of the flame‐retardant PLA composites, a compact and coherent charred layer was formed; the flame‐retardance mechanism is discussed in detail. J. VINYL ADDIT. TECHNOL., 22:506–513, 2016. © 2015 Society of Plastics Engineers