Types Of Polyvinyl Alcohol Research Articles

Appropriate selection of an aggregation inhibitor of fine particles used for inhalation prepared by emulsion solvent diffusion

Context: Dry powder inhaler (DPI) formulations have been developed to deliver large amounts of drugs to the lungs.Objective: Fine particles of a poorly water-soluble drug, the model drug ONO-2921, were prepared by the emulsion solvent diffusion (ESD) method for use in a DPI.Methods: The effects of additives on the fine particle formation of ONO-2921 were estimated when droplets of an ethanolic drug solution were dispersed into aqueous media containing various additives. Subsequently, the suspensions were freeze-dried to create powdered samples to estimate the inhalation properties using a twin impinger and an Andersen cascade impactor.Results: This simple ESD method produced submicron-sized ONO-2921 particles (approximately 600 nm) in combination with suitable additives. In addition, the freeze-dried powder produced using additives exhibited superior in vitro inhalation properties. Among these methods, the freeze-dried powder produced with 0.50% weight/volume one type of polyvinyl alcohol (PVA-205) displayed the most efficient features in the fine particle fraction (FPF). These results could be explained by the stabilization of the ONO-2921 suspension by PVA-205, indicating that PVA-205 acts as an aggregation inhibitor of fine particles.Conclusions: The ESD method, in combination with appropriate types and amounts of additives, may be useful for preparing a DPI suitable for delivering drugs directly to the lungs without the assistance of carrier particles.

Frost resistance of polyvinyl alcohol fiber and polypropylene fiber reinforced cementitious composites under freeze thaw cycling

This paper presents an experimental study that was conducted to clarify the effect of reinforcing short fiber characteristics such as the length, tensile strength, and adhesion on the frost resistance of fiber reinforced cementitious composites (FRCCs) by incorporating two types of polyvinyl alcohol (PVA) fibers and polypropylene (PP) fiber. FRCCs with a 1.5% volume ratio of fiber were investigated for frost resistance under freeze–thaw action of 300 cycles and were compared with non-fiber reinforced cementitious composite (Plan) specimens. The air void characteristics of mixtures were also investigated by mercury intrusion porosimetry (MIP), linear transverse method, and scanning electron microscope (SEM) images. The difference of the fiber type (PVA and PP) characteristics was affected by the dispersion of blended fibers in FRCCs and by the adhesion performance between the cementitious matrix and the fibers in the microstructure. Hence, the results of the compressive behavior indicated that the PVA FRCC specimens have superior resistance on the reduction of the compressive strength before and after freeze–thaw cycling compared to PP FRCC and Plain specimens. Additionally, the test results of the relative dynamic elastic modulus and mass loss indicated that the PVA FRCC specimens remain durability after freeze–thaw action of 300 cycles compared with virgin specimens. Therefore, the results of freeze–thaw tests revealed that the blending of PVA fibers to FRCC is considerably effective for frost resistance.

Behavior of high-performance fiber-reinforced cement composite columns subjected to horizontal biaxial and axial loads

Current design in the ACI building code for reinforced concrete columns under seismic load combinations requires reinforced detailing which causes reinforcement congestion and construction difficulties. As an alternative solution, the use of high-performance fiber-reinforced cement composites (HPFRCC) with an economical type of Poly Vinyl Alcohol (PVA) fibers in column elements was investigated in this paper. Six column specimens with 2/3 scale including three standard reinforced columns and three columns using PVA fibers were tested. In the research work herein presented, biaxial cyclic lateral loads were applied to specimens subjected to either 10% or 30% constant axial loads. The experimental results are presented and the global behaviors of the tested columns are discussed, particularly focusing on stiffness and strength degradations due to increasing cyclic demand. Test results indicated superior damage tolerance and stable inelastic load–displacement responses up to 5% or 9% drift for the HPFRCC columns, even though they suffered severe shear cracks. Specimens without PVA all showed very limited ductility and low strengths.

A novel multiple drug release system in vitro based on adjusting swelling core of emulsion electrospun nanofibers with core–sheath structure

We have developed a novel drug delivery system with the swelling core for differential release of multiple drugs by emulsion electrospinning, in which the aqueous phase is composed of polyvinyl alcohol and the oil phase consists of poly(ε-caprolactone). The microscopy images indicate that the W/O nanofibers with swelling core structure are successfully prepared and the model drugs, Rhodamine B and bovine serum albumin, were encapsulated in the fibers. In vitro drug release study demonstrated that this core–sheath structure could significantly alleviate the initial drug burst release and provided a differential diffusion pathway to release. It could be found that the postponement of the maximum accumulated release of bovine serum albumin was found due to the presence of sodium citrate and different types of polyvinyl alcohol. This study would provide a basis for optimization of encapsulation conditions to control the release of multiple agents and ultimately be applied in cancer chemotherapy.

In vitro study of anticancer activity of polymer-based DOX-ZnO compositions: the case of vinyl alcohol (co)polymers

To reduce toxicity and side effects of antitumor preparations as well as to promote their target delivery and action prolongation, nanosize carriers are used. Recently we have shown in vivo that zinc oxide compositions of chelates of salicylidene amino acids in the form of coatings and as a part of composite films with polyvinyl alcohol (PVA) revealed much higher (by a factor of 2.3-2.5) antitumor activity in comparison with the initial chelates of salicylidene amino acids and their composite films with PVA. The paper presents in vitro study of physicochemical properties and antitumor activity of doxorubicin (DOX) zinc oxide composites with various types of PVA for human cell system (normal MRC5 cells and HeLa cancer cells). A possibility of vectored (directed) regulation of DOX by variation of the polymer composition in doxorubicin zinc oxide compositions is demonstrated. It is determined that both PVA and ZnO do not reveal toxic properties in cell cultures. At the same time, DOX toxicity in zinc oxide compositions is reduced for both normal and cancer cells depending on PVA type in comparison with the initial PVA+DOX combined films. Almost all investigated composites have a beneficial selective toxic effect on cancer cells at minimum impact on normal tissues, and zinc oxide compositions in the form of modified PVA (МPVA+ DOX + ZnO) reveal higher efficiency of selective harmful (destructive) action than DOX.

Investigation of composites of polymers and Mo6S2I8 nanowires

We have dispersed Mo6S2I8 nanowires in different types of polyvinyl alcohol (PVA), polystyrene sulfonate (PSS) and surfactants, analyzing their effect on the quality of the dispersion. Raman spectroscopy was employed to investigates the nanowires from suspensions as well as in films. I–V characteristics of networks of nanowires, deposited from suspensions stabilized by PSS, were measured as function of temperature, observing, in the linear region, a variable‐range hopping behavior typical of disordered systems.

Property-based design: optimization and characterization of polyvinyl alcohol (PVA) hydrogel and PVA-matrix composite for artificial cornea

Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt.

Simple spectrophotometric method for determination of polyvinylalcohol in different types of wastewater

The determination of polyvinylalcohol (PVA) by the formation of the blue iodine–PVA complex method was established for a semi-micro method scale. The direct addition of iodine solution proved to be a better iodine source than iodine generated in situ. The ageing of reagents requires frequent calibrations. Common biopolymers such as starch, albumin and cellulose produced much lower colour intensity with reagents and their impact on the analysis is negligible. The method is not affected by paper filter filtration. The detection of PVA was successfully tested in different wastewater types and the method proved to be a powerful tool for PVA detection. It must be emphasised that quantification of PVA is strongly dependent on the PVA type and the quantification capacity; without information of the PVA structure or type is only tentative.

Development of deflection-hardening geopolymer-based ductile fibre reinforced cementitious composites

Ductile fibre reinforced cementitious composites (DFRCC) are cement-based composites reinforced with short random fibres (metallic and/or non-metallic) which exhibit deflection-hardening and multiple-cracking behaviours in bending. It is a special class of high performance fibre reinforced cementitious composite (HPFRCC) that has higher deflection capacity than that of regular fibre reinforced concrete (FRC). Current DFRCCs are limited to cement-rich matrix system. This paper reports the development of geopolymer-based DFRCC where the cement binder in DFRCC is replaced by fly ash-based geopolymer binder and alkaline liquids (sodium hydroxide and sodium silicate) are used to activate the fly ash. In this study, three types of fibres are considered namely steel and two types of polyvinyl alcohol (PVA) fibres having different diameter, length and elastic modulus. The fibres used in the development of both cement-based and geopolymer-based DFRCCs are limited to single fibre type. The effects of two different ...

An integrated experimental and modeling approach to propose biotinylated PLGA microparticles as versatile targeting vehicles for drug delivery.

Polymeric microparticles with covalently attached biotin are proposed as versatile targeting vehicles for drug delivery. The proposed microparticles made of 85/15 poly (lactic-co-glycolic acid) (PLGA) will have biotin available on the outside of the particle for the further attachment with an avidin group. Taking advantage of biotin’s high affinity for avidin, and avidin’s well-known chemistry, the particle has the potential to be easily coated with a variety of targeting moieties. This paper focuses on the design and resulting effect of adding biotin to PLGA microparticles using an integrated experimental and modeling approach. A fluorescent-tagged avidin (488-streptavidin) was used to confirm the presence and bioavailability of biotin on the outside of the particles. For the purpose of this study, bovine serum albumin (BSA) was used as a model therapeutic drug. Microparticles were created using two different types of polyvinyl alcohol 88 and 98 mol% hydrolyzed, which were then analyzed for their size, morphology, and encapsulation capacity of BSA. Release studies performed in vitro confirmed the slow release of the BSA over a 28-day period. Based on these release profiles, a release kinetics model was used to further quantify the effect of biotinylation of PLGA microparticles on their release characteristics by quantitatively extracting the effective drug diffusivity and drug desorption rate from the release profiles. It was found that the biotinylation of the PLGA microparticles slowed down both the drug desorption and drug diffusion process, which confirmed that biotinylated PLGA microparticles can be used for controlled drug release. The presented technology, as well as the proposed integrated experimental and modeling approach, forms a solid foundation for future studies using a cell-specific ligand that can be attached to avidin and incorporated onto the microparticles for targeted delivery.Electronic supplementary materialThe online version of this article (doi:10.1186/2194-0517-2-3) contains supplementary material, which is available to authorized users.

Effect of boric acid treatment method on the characteristics of poly(vinyl alcohol)/iodine polarizing film

AbstractFour types of polyvinyl alcohol (PVA)/iodine complex films were made using different boric acid treatments to prepare polarizing films having high durability under humid and warm atmospheres and to identify the effects of the boric acid treatment method on the formation of the PVA/iodine polarizing film. The four types of films were a PVA iodinated film(I), a PVA film that was iodinated and then treated with boric acid(I‐B), a PVA film that was treated with boric acid and then iodinated(B‐I), and a PVA film that was simultaneously treated with iodine and boric acid(I+B). The concentrations of I2/KI were 0.03, 0.05, and 0.07 mol/L, and the concentrations of boric acid were 0.1, 0.3, and 0.5 mol/L. Comparing four type films treated with 0.05 mol/L I2/KI and 0.5 mol/L boric acid, the conformation of PVA/iodine complexes for I‐B film were larger than the others. The degrees of polarization (ρ) of all of the films increased to very high levels (99.9%↑). The durability of I‐B was superior to B‐I or I+B, and the change in the ρ was below 5% because the boric acid treated after iodine treatment reduced the molecular mobility of the PVA/iodine complex chains through intracrosslinking, so that the PVA/iodine complex could not easily collapse. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Water-soluble Polyvinyl Alcohol Microspheres for Temporary Embolization: Development and in Vivo Characteristics in a Pig Kidney Model

To preliminarily examine whether solubility of water-soluble polyvinyl alcohol (PVA) microspheres in blood plasma changes in proportion to their degrees of saponification. The study also examined their feasibility as a temporary embolic agents in the pig renal artery. Three types of PVA microspheres with the degrees of saponification of 97 mol% (S97), 98 mol% (S98), and 99 mol% (S99) were prepared. Seven kidneys in seven miniature pigs were embolized and divided into three groups so there would be at least two kidneys for each type of PVA. One animal in each group was euthanized immediately after angiography at 3 hours after embolization and the other one at 7 days after. In addition, one animal embolized with S99 microspheres was euthanized at 21 days after embolization. With S97 microspheres, the vascular network had recovered to the preembolic state by 3 hours after embolization. With S98 microspheres, blood flow in the third-order branch had been restored in the same period. With S99 microspheres, the second- and lower order branches remained occluded until 21 days. Histopathologic specimens harvested at 3 hours revealed only a trace of PVA for S97 microspheres. With S98 microspheres, the vascular lumen was still found to be filled with PVA gel. With S99 microspheres, swollen microspheres densely filled the vascular lumen even on day 21. Dissolution process in vitro and the duration of arterial occlusion in vivo were possibly related to the degree of saponification of PVA. This result may support feasibility of PVA microspheres as a temporary embolic agent.

Grafting and adsorption of poly(vinyl) alcohol in vinyl acetate emulsion polymerization

Poly(vinyl alcohol) is often used in vinyl acetate emulsion polymerization as a protective colloid, but its role is complex and controversial since it partakes in grafting reactions with the monomer, influencing process mechanisms, and affecting the colloidal properties of the latex. Furthermore, in industrial operations, the wide scatter of macromolecular properties of the commercial types of poly(vinyl alcohol) causes process irreproducibilities. In this work different types of polyvinyl alcohol were used to perform a series of polymerizations, and their kinetics were compared. A selective solubilization procedure was applied to separate the three fractions of poly(vinyl alcohol) in the final latex: free in the water phase, physically adsorbed onto the polymer particles and chemically grafted. These results were compared with those obtained from pure adsorption measurements of polyvinyl alcohol onto ‘emulsifier-free’ polyvinyl acetate dispersions. The rheological behavior of the different latexes was also compared, and the results were used to formulate an hypothesis on the interaction mechanisms acting in these systems.

Thermal Lamination of Ink Jet Photo Papers

Many commercially available ink jet media have excellent print qualities, but are difficult to laminate. Generally, unprinted areas have better adhesion to laminating films than printed areas. The lamination of secondary colors is often more difficult than primary colors. Images printed with pigmented inks are often much harder to laminate well than images printed with dye based inks. It is shown that, depending on the composition of the coating, unprinted areas can have lower adhesion than printed ones. The type of polyvinyl alcohol in the ink jet receiving layer could have significant influence on the adhesion of the laminating film. Partially hydrolyzed polyvinyl alcohol has better adhesion to unprinted areas than fully hydrolyzed. On the other hand, fully hydrolyzed polyvinyl alcohol provides better adhesion with primary and secondary colors. A mechanism to describe the migration of high boiling ink solvents and their influence on laminate adhesion is provided.

Characterization of Low-molecular-weight Polyvinyl Alcohol for Restoration Purposes

Low molecular weight polyvinyl alcohol, used in the paper industry as a pigment coating adhesive, was tested as a re-sizing agent used in paper restoration to strengthen decayed papers. All of the tests (pH, degree of polymerisation, folding endurance, tensile strength, opacity, blue reflectance and reversibility) done after accelerated aging in different ambient conditions and for various lenghts of time resulted in very good results for the tested type of polyvinyl alcohol for the intended purpose

Vehicle effects in ophthalmic bioavailability: an evaluation of polymeric inserts containing pilocarpine.

A series of polymeric ophthalmic inserts containing pilocarpine were formulated with four different types of polyvinyl alcohol, PVA, and two types of hydroxypropylcellulose. Pilocarpine was present as the nitrate, or as the salt with polyacrylic acid, PAA. In-vivo miosis vs time experiments on albino rabbits, showed that all inserts increased significantly the bioavailability of pilocarpine, with respect to a standard solution of pilocarpine nitrate. Two PVA inserts, containing the PAA-salt of pilocarpine, were particularly effective. The preparations were also submitted to in-vitro release tests and to differential scanning calorimetry, to ascertain the release mechanism, and to verify, via the thermal behaviour, possible interactions between drug and polymers. The chemical and physiochemical factors, most likely to influence the ophthalmic bioavailability of pilocarpine from the present preparations, are briefly reviewed.

A quantitative study of the effects of different grades of polyvinyl alcohol on the activities of certain enzymes in unfixed tissue sections.

Different grades of the colloid stabilizer, polyvinyl alcohol, used for protecting unfixed cryostat sections during cytochemical reactions, may have different effects on enzymatic activity. The influence of three grades of polyvinyl alcohol on the activities of "soluble", membrane-bound and membrane-enclosed enzymes has been investigated in unfixed sections; the activities were measured microdensitometrically. The largest molecular weight polyvinyl alcohol (G18/140, mol. wt. about 90 000) did not retain glucose-6-phosphate dehydrogenase activity in sections of rat liver even when used at the maximum convenient concentration (12%); G04/140 and M05/140 (molecular weights of 15 000 and 25 000 respectively) retained this soluble enzyme if used at concentrations of 30 and 20% respectively. At these concentrations, lactate dehydrogenase activity was apparently decreased when G04/140 and M05/140 were used; this diminished activity has been shown to be due to the need to establish optimal concentrations of reactants for each grade of polyvinyl alcohol and for each reaction. When optimal concentrations of reactants were used, the activities of this enzyme in the presence of each grade of polyvinyl alcohol were identical. The presence of any type of polyvinyl alcohol did not influence the activities of mitochondrial succinate dehydrogenase or of the smooth endoplasmic reticulum enzyme, delta5,3beta-hydroxysteroid dehydrogenase. However, the presence of polyvinyl alcohol improved the state of the section.

Polyvinyl Alcohol as a Warp Size for Various Staple Yarns1

Polyvinyl alcohol has been evaluated as a warp size for cotton, Dacron 4 polyester staple yarn, and blends of Dacron staple with cotton and viscose rayon. Under simu lated weaving conditions, superior sizing performance on all these yarns was given by completely hydrolyzed, high viscosity product. This type of polyvinyl alcohol also proved to be effective as an extender for various sizes based on starch or modified starch. The size formulations tested are described.