Stability Of Polyvinyl Alcohol Research Articles

Exploring the efficacy of various essential oils in chitosan‐based composite biopolymer films for food packaging

AbstractTo ensure food and environmental safety, biodegradable packaging materials from various natural polymers are being used to preserve the high quality of foods and to increase their shelf life in addition to environmental safety in terms of biodegradability. However, these natural polymers have some disadvantages in functionality. There are many ways to improve functionality, one such way is the addition of essential oils. Therefore, this research work was done to investigate the effectiveness of four diverse essential oils (EOs), namely, lemon‐grass oil (LGO), tea‐tree oil (TTO), thyme oil (THO), and basil oil (BO) in chitosan‐based composite films. The chitosan as a biopolymer, polyvinyl alcohol (PVA) as a compatibilizer, and four different essential oils@0.3% were blended to form composite food packaging films. These nanofilms had better mechanical strength, elasticity, and film thickness. Thermal stability and change in the weight of chitosan alone and composite films were determined by thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) was used to analyze the change in film surface morphology. The Fourier transform infrared (FTIR) spectrum of the base polymer exhibits characteristic peaks at 3400 cm−1 indicating the occurrence of hydrogen‐bonded OH groups, and peaks at 1500–1600 cm−1 corresponding to the amide II band and CO stretch of the acetyl group. Whereas TGA results confirmed the thermal stability of PVA and EO blended films compared to chitosan alone films. The biodegradability of antimicrobial chitosan‐based films exhibited around 15%–19% percentage of degradation in PVA blended films whereas chitosan alone degraded up to 32% after 30 days. Water vapor transmission was high in chitosan alone film (1.9%) and 0.25% in PVA/EO blended films displaying enhancement in hydrophobic qualities of the developed films due to change in hydrophobicity by EO addition. The chitosan and PVA alone films were transparent whereas EO blended films exhibited yellow coloration and became less transparent due to the oil droplets dispersion in films. The shelf life of tomato, bread, and paneer was better in lemongrass and tea tree oil‐incorporated films during storage.

Preparation and characterisation of polyvinyl alcohol/glycerol blend thin films for sustainable flexibility

Petroleum-based polymers pose significant environmental challenges; this prompts researchers to seek alternatives for the same. The foremost solution to replace petroleum-based packaging lies in bio-based polymers that can degrade with water, soil, and the environment. The most common and economical bio-based polymer today is polyvinyl alcohol (PVA), however, it has certain limitations such as brittleness, hydrophilic nature, etc. The primary objective of this study is to enhance the flexibility, transparency, barrier properties, and thermal stability of PVA by incorporating glycerol as a plasticizer. In this regard, thin films were prepared by utilizing a solution-casting technique (blade coating) upon the addition of numerous concentrations of glycerol ranging from 1 to 5 wt%. Here two sets of thin films were prepared i.e., with glycerol (modified) and without glycerol (pure PVA). Results suggest exceptional mechanical flexibility and enhanced optical properties in terms of improved transmittance (>90%) upon incorporation of glycerol into PVA. The modified films also demonstrated a significant increase in their water barrier capabilities in comparison to pure PVA films. When the concentration of glycerol reached to 5 wt%, a substantial increase in biodegradability and flexibility was witnessed resulting in reduced brittleness. Thus, the mechanical properties of the modified thin films exceeded that of pure PVA counterparts. The prepared thin films unveil exciting possibilities to be used in diverse applications; such as food packaging, membranes, biodegradable materials, etc,. The extensive discussion is presented in the light of observed results.

A computational and experimental investigation of TEOS-treated graphene oxide-PVA interaction: Molecular dynamics simulation and COSMO-RS insights

This research investigates the effect of tetraethyl orthosilicate TEOS on the interaction mechanism in the hybrid polyvinyl alcohol (PVA)/graphene oxide (GO) material. PVA, PVA/Go, and PVA/GO-SiO2 are produced by the solution casting method. The TEOS treated GO is confirmed by FTIR and also suggests that PVA is chemically bonded to GO-SiO2. XRD results reveal that the crystallinity of PVA is significantly reduced with the addition of TEOS as it becomes completely amorphous and shows that the GO has a full exfoliation in the matrix. However, thermogravimetric analysis indicates that the incorporation of GO improves the thermal stability of PVA by reducing its mass-loss rate upon heating. Theoretical molecular dynamic simulations indicate that the addition of SiO2 could significantly improve the binding interaction energies from 14387 kcal/mol to 15039 kcal/mol for 6PVA/3GO and 6PVA/3GO-3SiO2 systems, respectively. These simulations also highlight the occurrence of a hydrogen bonding between PVA and GO oxygen groups and PVA and Si-OH groups. The Conductor-like Screening Model for Real Solvents (COSMO-RS) study shows the intermediary role played by SiO2, which increases the compatibility between PVA and GO. The theoretical blend study also led to the conclusion that the three molecules could be mixed over the entire temperature range. Overall, these results suggest that TEOS can be successfully employed for the functionalization of PVA/GO hybrid materials, as it strengthens the interaction of the organic and inorganic phases.

In situ syringe rotation system for heavy microparticle suspension stability in electrospinning technique.

Electrospinning allows the fabrication of polymeric nonwovens with a wide variety of inclusions in the micro-nanofibers. However, the electrospinning of microparticle-filled polymer solutions is still limited in particle size, density, and concentration, mainly due to suspension instability during the electrospinning process, so it is not commonly investigated despite the vast number of possible applications. In this study, a simple and effective novel rotation device was developed to prevent the settling of microparticles in the polymer solution during electrospinning. The stability of polyvinyl alcohol and polyvinylidene fluoride (PVDF) solutions with indium microparticles (IMPs) of (42 ± 7) μm diameter was evaluated using LASER transmittance inside a syringe, both static and rotating for 24h. While the static suspensions completely settled at 7minand 9h, respectively, depending on solution viscosity, the rotating suspensions remained stable throughout the experiment. The number and distribution of IMPs in PVDF electrospun mats were determined by optic microscopy and a novel x-ray imaging mapping method, showing 165% more IMPs in the mat obtained with the rotating syringe device. A simple analysis of the theoretical background of settling and rotating suspensions was included to understand the working mechanism of the device. Also, the electrospinning of solutions with high loadings of IMPs (up to 400% w/w PVDF) was accomplished. The simplicity and outstanding efficiency of the device shown in this work may serve as a solution to technical difficulties and as an encouragement to future research in microparticle-filled solution electrospinning.

Colloidal Stability of CA, SDS and PVA Coated Iron Oxide Nanoparticles (IONPs): Effect of Molar Ratio and Salinity.

Iron Oxide Nanoparticles (IONPs) have received unprecedented interest in various applications. The main challenges in IONPs are fluid stability due to agglomeration in a saline condition. This paper aims to investigate the colloidal stability of citric acid (CA), sodium dodecyl sulphate (SDS) and polyvinyl alcohol (PVA) under various molar ratios and levels of salinity. Firstly, the IONPs were synthesized using a facile co-precipitation approach. Secondly, the IONPs were coated using a simple dip-coating method by varying the molar ratio of CA, SDS and PVA. Next, the coated IONPs were characterized by using an X-ray Diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), and a Field Emission Scanning Electron Microscope (FESEM) for the morphological and crystallographic study of coated IONPs. Finally, the coated IONPs were characterized for their zeta potential value and hydrodynamic size using a Zetasizer and their turbidity was measured using a turbidity meter. It was found that at a low salinity level, 0.07 M of CA-IONPs, a high zeta potential value, a smaller hydrodynamic size, and a high turbidity value of -40.9 mV, 192 nm and 159 NTU were observed, respectively. At a high salinity level, 1.0 M SDS-IONPs recorded a high zeta potential value of 23.63 mV, which corresponds to a smaller hydrodynamic size (3955 nm) and high turbidity result (639 NTU). These findings are beneficial for delivering cutting-edge knowledge, especially in enhanced oil recovery (EOR) applications.

Investigation on Reinforcement Effects of Nanocellulose on the Mechanical Properties, Water Absorption Capacity, Biodegradability, Optical Properties, and Thermal Stability of a Polyvinyl Alcohol Nanocomposite Film

This paper presents the reinforcement of nanocellulose (NC) in polyvinyl alcohol (PVA) to examine the effect of the amount of reinforcement on the properties of PVA. The nanocellulose was successfully extracted by sulfuric acid hydrolysis method and ultrasonication, and successively reinforced with polyvinyl alcohol by the solvent-casting method. After incorporating nanocellulose into the PVA matrix, the effect of nanocellulose on the tensile strength, elongation at break, water absorption capacity, transmittance, thermal stability, and biodegradability of PVA was investigated. The tensile strength increased from 24.5 ± 0.53 MPa to 35.5 ± 0.55 MPa and 40.6 ± 0.73 MPa with the addition of 2%NC and 5%NC, respectively. The elongation at break increased from 40 ± 0.53 % to 45.7 ± 0.53 % with 2%NC, and after the reinforcement of 7%NC, it decreased to 32.2 ± 0.75 % . The water absorption capacity result reveals that neat PVA absorbs the highest amount of water which is 84.6 ± 0.56 % and is reduced to 73 ± 0.78 % by adding 2%NC. By increasing the nanocellulose loading to 7%, the water intake capacity was reduced to 61 ± 0.59 % which illustrates the water intake was reduced linearly with the increment of NC. The ultraviolet-visible (UV-Vis) result implies that the transmittance of neat PVA and PVA-2%NC composite film was 85.4% and 78.2% at 600 nm, respectively, which indicates the decrement in transmittance. The thermogravimetry analysis (TGA) reveals that the thermal stability of polyvinyl alcohol after incorporating nanocellulose particles was reduced. The weight loss of neat PVA is 70.7 ± 1.7 % after 90 days while the weight loss of the PVA composite films reinforced with 1%, 3%, 5%, 7%, and 9% was 65 ± 1.85 % , 57 ± 1.57 % , 55.6 ± 0.64 % , 52 ± 1.73 % , and 53.1 ± 1.72 % , respectively. The scanning electron microscopy micrograph for the PVA-6%NC nanocomposite film reveals a dispersion of nanocellulose in a matrix.

Effect of Solvents, Stabilizers and the Concentration of Stabilizers on the Physical Properties of Poly(d,l-lactide-co-glycolide) Nanoparticles: Encapsulation, In Vitro Release of Indomethacin and Cytotoxicity against HepG2-Cell

A biocompatible, biodegradable and FDA-approved polymer [Poly lactic-co-glycolic acid (PLGA)] was used to prepare the nanoparticles (NPs) to observe the effect of solvents, stabilizers and their concentrations on the physical properties of the PLGA-NPs, following the encapsulation and in vitro release of Indomethacin (IND). PLGA-NPs were prepared by the single-emulsion solvent evaporation technique using dichloromethane (DCM)/chloroform as the organic phase with Polyvinyl-alcohol (PVA)/Polyvinylpyrrolidone (PVP) as stabilizers to encapsulate IND. The effects of different proportions of PVA/PVP with DCM/chloroform on the physiochemical properties (particle size, the polydispersity index, the zeta potential by Malvern Zetasizer and morphology by SEM) of the NPs were investigated. DSC was used to check the physical state, the possible complexation of PLGA with stabilizer(s) and the crystallinity of the encapsulated drug. Stabilizers at all concentrations produced spherical, regular-shaped, smooth-surfaced discrete NPs. Average size of 273.2–563.9 nm was obtained when PVA (stabilizer) with DCM, whereas it ranged from 317.6 to 588.1 nm with chloroform. The particle size was 273.2–563.9 nm when PVP was the stabilizer with DCM, while it was 381.4–466.6 nm with chloroform. The zeta potentials of PVA-stabilized NPs were low and negative (−0.62 mV) while they were comparatively higher and positive for PVP-stabilized NPs (+17.73 mV). Finally, drug-loaded optimal NPs were composed of PLGA (40 mg) and IND (4 mg) in 1 mL DCM/chloroform with PVA/PVP (1–3%), which resulted in sufficient encapsulation (54.94–74.86%) and drug loading (4.99–6.81%). No endothermic peak of PVA/PVP appeared in the optimized formulation, which indicated the amorphous state of IND in the core of the PLGA-NPs. The in vitro release study indicated a sustained release of IND (32.83–52.16%) from the PLGA-NPs till 72 h and primarily followed the Higuchi matrix release kinetics followed by Korsmeyer–Peppas models. The cell proliferation assay clearly established that the organic solvents used to prepare PLGA-NPs had evaporated. The PLGA-NPs did not show any particular toxicity in the HepG2 cells within the dose range of IND (250–500 µg/mL) and at an equivalent concentration of PLGA-NPs (3571.4–7142.7 µg/mL). The cytotoxicity of the hepatotoxic drug (IND) was reduced by its encapsulation into PLGA-NPs. The outcomes of this investigation could be implemented to prepare PLGA-NPs of acceptable properties for the encapsulation of low/high molecular weight drugs. It would be useful for further in vitro and in vivo applications to use this delivery system.

Preparation of nanocellulose-polyvinyl alcohol composite hydrogels from Desmodium intortum (Mill.) Urb.: Chemical property characterization

Nanocrystalline cellulose (NCC) was extracted from Desmodium intortum (Mill.) Urb. by sulfuric acid hydrolysis, and the NCC and polyvinyl alcohol (PVA) were fused together by repeated freezing and thawing cycles to obtain nanofiber-polyethylene. The alcohol composite hydrogel was characterized by XRD, FTIR, and SEM methods. The results showed that nanocellulose is primarily blended with polyvinyl alcohol through physical cross-linking, and the water retention of the composite hydrogel is obvious. Specifically, when the amount of NCC added was 0.4%, the water content increased to 94.26%. In short, the nanocellulose extracted from Desmodium intortum (Mill.) Urb. can effectively improve the water retention and thermal stability of PVA, which provides an effective theoretical basis for the hydrogel in medical dressings and improves the application value of Desmodium intortum (Mill.) Urb.

Development and characterization of polyvinyl alcohol filled with date palm midrib powder

Date palm ( Phoenix dactylifera L) is one of the most widely cultivated crops in different parts of Saudi Arabia. The midribs rich in cellulose, hemicellulose, and lignin are often burnt in the farms, causes severe environmental problems. In the present study, date palm midrib (DPM), these waste materials were powdered and incorporated into polyvinyl alcohol (PVA). Composites were prepared by varying the DPM loading (0–10 wt.%) using the solution casting method. Tensile and thermal properties were analyzed for the composites with respect to filler loading. Addition of DPM as filler enhanced the tensile modulus while an inverse effect was observed in the elongation values. Differential scanning calorimeter (DSC) analysis showed a gradual increase in melting temperature (Tm) and crystallinity values for PVA. Thermogravimetric analysis (TGA) indicated that the incorporation of DPM into PVA can increase the thermal stability of PVA. Morphology of the composites was performed using scanning electron microscopy (SEM).

Preparation of Silver Nanoparticles in a Plasma-Liquid System in the Presence of PVA: Antimicrobial, Catalytic, and Sensing Properties

The preparation of stabilized silver nanodispersions under the action of short-term plasma discharge using a polyvinyl alcohol stabilizer (polyvinyl alcohol (PVA)) was investigated. The influence of the basic technological parameters such as initial Ag+ concentration, PVA concentration, and process duration on the formation of nanoparticles and their characteristics (size and stability) were determined. The UV-Vis spectra showed the localized surface plasmon resonance at wavelengths of 400–420 nm. The SEM images showed that the shape of Ag NPs is spherical with an average particle size up to 30 nm. Ag NPs were used as a catalyst for the reduction of 4-nitrophenol (4-NP). The effect of the concentration of PNP and catalyst dosage on the value of apparent rate constant (kapp) for catalytic reduction of 4-NP in the presence of Ag NPs was investigated by means of UV-Vis spectrophotometry. The antimicrobial activity of Ag nanoparticles was investigated against yeast and Escherichia coli. The colorimetric sensor studies of plasma synthesized Ag NPs showed selective sensing of the potentially hazardous Hg2+ ion in water.

Supramolecular adsorption of cyclodextrin/polyvinyl alcohol film for purification of organic wastewater

AbstractInto purified organic wastewater, α-, β-, and γ-cyclodextrin (α-, β-, and γ-CD) were added to polyvinyl alcohol (PVA) with ammonium persulfate as the crosslinker. The CD/PVA composite film with low water solubility and supramolecular adsorption was prepared by solvent evaporation. Fourier transform infrared spectroscopy showed that when CD was successfully added to PVA, the crosslinking process had no effect on -OH, and the structure was stable after soaking in water for 120 h. Solubility experiments showed that the stability of PVA in water was significantly improved. The results of phenolphthalein adsorption showed that the composite film followed the Langmuir isothermal adsorption and the pseudo-second-order kinetics. According to the Langmuir equation, the theoretical maximum adsorption capacities of α-, β- and γ-CD/PVA composite films were 0.41, 2.05, and 2.00 mg/g, respectively. The parameters of the Freundlich equation indicate that the adsorption of the composite film is physical adsorption. The time for α-CD/PVA composite film to reach equilibrium was the shortest, while the longest was for β-CD/PVA composite film. The intraparticle diffusion model showed that the adsorption was mainly affected by the diffusion of the boundary layer, and the diffusion rate limitation of the boundary layer of the high-concentration phenolphthalein solution was more obvious.

Preparation and characterization of polyvinyl alcohol–starch composites reinforced with pulp

Herein, we have investigated the reinforcing potential of starch and cellulose pulp in a matrix of polyvinyl alcohol (PVA). Polyvinyl alcohol, starch, and pulp fibers having different compositions were constructed in order to achieve better reinforced composite films. Various techniques were utilized for extract the physical, mechanical as well as thermal properties. The magnitudes of tensile strength were reduced with rising of starch content in PVA. Tensile strength values of (PVA + starch) mixtures were enhanced with the enhancement of pulp fibers content. The properties of bulk density and water absorption revealed the significant impact of starch and pulp fibers. The obtained result of thermal stability of PVA was superior which was reduced by addition of starch content; therefore, regained with the insertion of pulp fibers content in PVA–starch matrix.

Mechanical and thermal properties of rice straw cellulose nanofibrils-enhanced polyvinyl alcohol films using freezing-and-thawing cycle method

This study investigated effects of loadings of rice straw (Oryza sativa L.) cellulose nanofibrils (CNFs) defibrillated using the high-pressure homogenization technique on tensile property, glass transition temperature, and thermal stability of polyvinyl alcohol (PVA) matrix. CNF loadings had five percentage levels by weight of final composite, i.e. 0, 0.03, 0.08, 0.12, and 0.17%, respectively. A freezing-and-thawing cycle method cast PVA/CNF-mixed and PVA-only films. Experimental results showed that PVA films with 0.03% CNFs had average tensile strength of 50.8 MPa and modulus of 707 MPa, which were 32 and 21% higher than neat PVA ones, respectively. In addition, the glass transition temperature values of PVA/CNF-mixed film increased from 51.6% to 82.6% with increasing the amount of CNFs. The thermogravimetric analysis showed that PVA/CNF-mixed films had significantly higher thermal stability than PVA-only films. The shift of the O–H stretching vibration peak in PVA/CNF-mixed films indicated a good compatibility between CNFs and PVA matrix.

Mechanical performance and thermal stability of polyvinyl alcohol–cellulose aerogels by freeze drying

Polyvinyl alcohol (PVA)/cellulose nanofibers (CNFs)/Gelatin hybrid organic aerogels were synthesized using a facile and environmentally friendly freeze-drying method. The biobased gelatin acted as a cross-linking agent and combined PVA and CNFs tightly by hydrogen bonds. The composites were characterized and analyzed by various techniques including uniaxial compression test, scanning electron microscopy, as well as thermal conductivity analysis and TGA–DTG analyses. The mechanical properties were strengthened significantly with the introduction of a small amount of gelatin. The modulus of PVA/CNF/G3 was 1.65 MPa, nearly eightfold of the PVA/CNF aerogel and 91 times higher than the neat CNF aerogel. Microstructure analyses revealed the three-dimensional network of the aerogels. The composites also possess good thermal stability, low density, and low thermal conductivity. Therefore they have broad prospects in the field of thermal insulation.

Preparation and characterization of nanocomposite films from oil palm pulp nanocellulose/poly (Vinyl alcohol) by casting method

TEMPO-oxidize nanocellulose (TONC) suspension has been obtained from total chlorine free (TCF) oil palm empty-fruit-bunches (OPEFB) pulp using 4-acetamido-TEMPO (2,2,6,6-tetramethyl piperidin-1-oxyl) mediated oxidation with sodium hypochlorite and sodium bromide in water at 25 °C and pH 10. TONC suspension with varied content from 0.5 to 6% (w/w) reinforced polyvinyl alcohol (PVA) polymer based nanocomposite films were prepared by the casting method. The structural interaction between the TONC and PVA was characterized by the Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the 4% (w/w) TONC content reinforced nanocomposite exhibited the highest tensile strength and modulus with an increase of 122% and 291% respectively, compared to PVA while the elongation at break decreased about 42.7%. Thermal stability of PVA based nanocomposite films was improved after incorporation of TONC. Incorporation of TONC in PVA film increases its crystallinity due to strongly linking between the hydroxyl groups of materials however considerable decreases beyond 2 wt% loading are observed. TONC incorporation beyond 2 wt% also reduces the melting temperature peaks and enthalpy of nanocomposite films. FT-IR spectra, NMR and SEM indicate that there is interaction between the TONC and PVA.

TiO2/PANI nanocomposite loaded in PVA for anticorrosive applications

Abstract We report the morphological and electrical study of a composite of polyvinyl alcohol (PVA) and nanotitanium dioxide (TiO2-50 nm) in conducting polymer polyaniline (PANI). The composite was synthesized using in-situ polymerization technique. The composite was characterized in terms of morphology and electrical properties using scanning electron microscopy and DC electrical conductivity (𝜎dc). We observed that the DC electrical conductivity of the composite film increased with increasing the loading of nanocomposite material from 20 % to 40 % into PVA stabilizer. The DC conductivity results showed that the molecular chain contribution of the nanocomposite material (nano-TiO2+ PANI) was the prominent carrier in the composite film made of the nanocomposite and PVA stabilizer.

Influence of CdS nano-additives on optical, thermal and mechanical performance of CdS/polyvinyl alcohol nanocomposites

CdS/PVA nanocomposites have been prepared by solution casting method where 0.5, 1, 2 and 3wt% of CdS nanoparticles (NPs) were added to polyvinyl alcohol (PVA) polymer as filler. The structure identification of PVA and CdS/PVA nanocomposites films was carried out by the X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle size of CdS in PVA matrix was in nano-scale and increases gradually with the increasing of CdS NPs ratio. The thermal stability of PVA and CdS/PVA films has been evaluated using thermogravimetric analysis (TGA). Mechanical properties (tensile strength and elongation) of CdS/PVA films have been discussed in terms of the dispersion of CdS NPs into PVA polymer matrix and the ratio of CdS NPs. PVA and CdS/PVA films all of them have direct optical band gap which was decreased by increasing of CdS NPs ratio.The effect of concentration of the filler particles (CdS NPs) and γ-irradiation, with different doses on the thermal stability, mechanical properties and optical band gap of CdS/PVA nanocomposites films has been studied.

Thermal behavior of polyvinyl alcohol–gellan gum–Al3+ composite hydrogels with improved network structure and mechanical property

In this work, the composite hydrogels of polyvinyl alcohol (PVA)–gellan gum (GG)–aluminum ion (Al3+) have been prepared by a repeated freezing and thawing method. By analyzing its structure, mechanical properties and thermal behavior, our result indicates that the ion of Al3+ plays a role of cross-link agent, and it reorganizes the network structure and enhances the mechanical properties for the composite hydrogels. Differential scanning calorimetry has been used to examine the thermal behavior. The melting enthalpy was obtained to evaluate the degree of crystallinity for PVA in hydrogel, which decreases with the increase in the content of GG. The decomposition temperature was obtained to evaluate the thermal stability. And the dehydration activation energy was obtained to evaluate the thermal behavior of water in hydrogel environment. Our result reveals that Al3+ ion enhances the molecular interactions between water and polymer chain, and improves the thermal stability of PVA–GG–Al3+ composite hydrogel. These results will benefit the development of hydrogel in bio-applications.

Development of tunable biodegradable polyhydroxyalkanoates microspheres for controlled delivery of tetracycline for treating periodontal disease

ABSTRACTThis article was aimed at preparation and characterization of drug delivery carriers made from biodegradable polyhydroxyalkanoates (PHAs) for slow release of tetracycline (TC) for periodontal treatment. Four PHA variants; polyhydroxybutyrate (PHB), poly(hydroxybutyrate‐co‐hydroxyvalerate) with 5, 12, and 50% hydroxyvalerate were used to formulate TC‐loaded PHA microspheres by double emulsion‐solvent evaporation method. We also compared the effect of different molecular weight (Mw) of polyvinyl alcohol (PVA) acting as surface stabilizer on particle size, drug loading, encapsulation efficiency, and drug release profile. The TC‐loaded PHA microspheres exhibited microscale and nanoscale spherical morphology under scanning electron microscopy. Among formulations, TC‐loaded PHB:low Mw PVA demonstrated the highest TC loading with slow release behavior. Our results showed that the release rate from PHA microspheres was influenced by both the type of PHA and Mw of PVA stabilizer. Lastly, TC‐loaded PHB microspheres showed efficient killing activity against periodontitis‐causing bacteria, suggesting its potential application for treating periodontal disease. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44128.

Cellulose nanofibers from the skin of beavertail cactus, Opuntia basilaris, as reinforcements for polyvinyl alcohol

ABSTRACTIn this study, the skin of the beavertail cactus, Opuntia Basilaris, was used for the isolation of cellulose nanofibers using a chemo‐mechanical technique. It was shown that the skins had a relatively high cellulose content, whereas their lignin content was low. Fourier transform infrared spectroscopy and X‐ray diffraction proved that the isolation of cellulose nanofibers from the amorphous components of the skins was performed successfully. The cactus skins were also shown to have a high content of calcium oxalate crystals. Morphological observations proved that the isolated cellulose fibers had diameters in the range of 10–50 nm. It was shown that the addition of nanofibers increased the modulus and strength of the polyvinyl alcohol matrix significantly, whereas the elongation at break decreased. Thermogravimetric analysis proved that: (i) isolated nanofibers had higher thermal stabilities than the cactus skins, and (ii) inclusion of nanofibers increased the stability of polyvinyl alcohol noticeably. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42499.