Improved Release of a Drug with Poor Water Solubility by Using Electrospun Water-Soluble Polymers as Carriers

In an attempt to improve the solubility of valsartan, a BCS II drug, fibers containing the drug were prepared from three water-soluble polymers, hydroxypropyl-methyl-cellulose (HPMC), polyvinyl-pyrrolidone (PVP), and polyvinyl-alcohol (PVA). Fiber spinning technology was optimized for each polymer separately. The polymers contained 20 wt% of the active component. The drug was homogenously distributed within the fibers in the amorphous form. The presence of the drug interfered with the spinning process only slightly, the diameters of the fibers were in the same range as without the drug for the HPMC and the PVA fibers, while it doubled in PVP. The incorporation of the drug into the fibers increased its solubility in all cases compared to that of the neat drug. The solubility of the drug itself depends very much on pH and this sensitivity remained the same in the HPMC and PVP fibers; the release of the drug is dominated by the dissolution behavior of valsartan itself. On the other hand, solubility and the rate of release were practically independent of pH in the PVA fibers. The different behavior is explained by the rate of the dissolution of the respective polymer, which is larger for HPMC and PVP, and smaller for PVA than the dissolution rate of the drug. The larger extent of release compared to neat valsartan can be explained by the lack of crystallinity of the drug, its better dispersion, and the larger surface area of the fibers. Considering all facts, the preparation of electrospun devices from valsartan and water-soluble polymers is beneficial, and the use of PVA is more advantageous than that of the other two polymers.

Compression and Flexural Behavior of ECC Containing PVA Fiber

Research on Engineered Cementitious Composites (ECC) is overwhelming owing to its wide structural applications that can serve multi-functional purposes in civil and nvironmental infrastructures. Compared to other high-performance fiber reinforced concrete, ECC yields superior tensile ductility and multiple cracking behaviors when subjected to tensile loadings even with low to moderate volume of fibers. This paper presents the flexural properties of ECC made of cement, an industrial by-product, such as ground granulated blast-furnace slags (GGBS), local silica sand, polyvinyl alcohol (PVA) fiber, water, and superplasticizer (SP). Two series of ECC mixtures (ECC-G50 series and ECC-G60 series) and one control mixture were designed. The effect of two different fiber contents in volume fraction was investigated for the two series of ECC mixtures. The compression and flexural tests were conducted on ECC and control specimens after 28 days of curing. A compression test revealed that almost all ECC mixtures improved compressive strength between 20% to 30% compared to the control specimens. In addition, all ECC plate specimens demonstrated excellent strain-hardening states (i.e., displacement capacity at least ten times greater than the control specimens) and multiple fine-cracks failure modes after the three-point bending test. The increase in fiber content slightly reduced the compressive strength but enhanced the flexural behavior of the ECC-G50 series. However, this observation is not discovered in the ECC-G60 series. Outcomes of this research assist material scientists on the content of PVA fiber and GGBS used in making ECC.

Appraisal on low cost and sustainable ECC using microfibers in hybridization at later age

The addition of supplementary cementitious materials and fiber plays an important role in the mechanical and durability performance of ECC matrix. In the present research work, the assessment of the performance of ECC matrix with the utilization of iron industry waste and microfibers has been done. Three types of microfibers, i.e., polyvinyl alcohol (PVA) fiber, polyester (PET) fiber, and microsteel (MSE) fiber, were used at various percentages in hybridization to prepare total seven mixes. First, PVA was switched by PET fiber at dosages 5%, 10%, 15%, 20%,and 25% and afterwards another 25% by MSE fiber. The performance of various matrix proportions was judged based on the flexural response, electrical resistivity, air permeability, and sorptivity characteristics to introduce sustainable and cost effective ECC matrix. Test results revealed that hybridization of fibers enhanced the flexural and durability performance of ECC and also produced a cost effective and sustainable ECC matrix.

Experimental Investigation on Dynamic Tensile Behaviors of Engineered Cementitious Composites Reinforced with Steel Grid and Fibers

Engineered cementitious composites (ECC) used as runway pavement material may suffer different strain rate loads such as aircraft taxiing, earthquakes, crash impacts, or blasts. In this paper, the dynamic tensile behaviors of the steel grid-polyvinyl alcohol (PVA) fiber and KEVLAR fiber-reinforced ECC were investigated by dynamic tensile tests at medium strain rates. The mixture was designed with different volume fractions of fibers and layer numbers of steel grids to explore the reinforcement effectiveness on the dynamic performance of the ECC. The volume fractions of these two types of fibers were 0%, 0.5%, 1%, 1.5%, and 2% of the ECC matrix, respectively. The layer numbers of the steel grid were 0, 1, and 2. The dynamic tensile behaviors of the PVA fiber and the KEVLAR fiber-reinforced ECC were also compared. The experimental results indicate that under dynamic tensile loads, the PVA-ECC reveals a ductile and multi-cracking failure behavior, and the KEVLAR-ECC displays a brittle failure behavior. The addition of the PVA fiber and the KEVLAR fiber can improve the tensile peak stress of the ECC matrix. For the specimens A0.5, A1, A1.5, and A2.0, the peak stress increases by 84.3%, 149.4%, 209.6%, and 237.3%, respectively, compared to the matrix specimen. For the specimens K0.5, K1, K1.5, and K2, the peak stress increases by about 72.3%, 147.0%, 195.2%, and 263.9%, respectively, compared to the matrix specimen. The optimum fiber volume content is 1.5% for the PVA-ECC and the KEVLAR-ECC. The KEVLAR-ECC can supply a higher tensile strength than the PVA-ECC, but the PVA-ECC reveals more prominent deformation capacity and energy dissipation performance than the KEVLAR-ECC. Embedding steel grid can improve the tensile peak stress and the energy dissipation of the ECC matrix. For the strain rate of 10−3 s−1, the peak stress of the A0.5S1 and A0.5S2 specimens increases by about 49.1% and 105.7% compared to the A0.5 specimen, and the peak stress of the K0.5S1 and K0.5S2 specimens increases by about 61.5% and 95.8%, respectively, compared to the K0.5 specimen.

Experimental Study on the Mechanical Properties of the Fiber Cement Mortar Containing Polyurethane

Polymer is a kind of high molecular elastic material. The polymer cement mortar composite material formed by mixing it with cement mortar has the advantages of light weight, high strength, and good durability compared with traditional mortar materials. The effect of polyurethane polymer content on mechanical properties and microstructure of polyvinyl alcohol (PVA) fiber cement mortar was studied by compressive test, flexural test, and SEM analysis. The test results show that as the content of polyurethane increases, the compressive strength gradually decreases, and the flexural strength gradually increases. The addition of polyurethane helps to optimize the microstructure of PVA mortar, improve the compactness of the material, and enhance the bending resistance of the mortar. The mechanical properties of materials obtained from the experiment can provide references for engineering applications.

Strength assessment of concrete using rice husk ash, recycled concrete aggregate and polyvinyl alcohol fiber

: This research work present the finest proper mix by adding and replacing with some other admixture materials having same properties as standard concrete materials. The substances that are used in this Rice husk ash (RHA) Recycled concrete aggregates (RCA) and polyvinyl alcohol fiber (PVA). Coarse aggregates was replaced with RCA at 50% and 0-20% RHA in scheming concrete mixes. For this, 5 to 20% (such as 5%, 10%, 15% and 20%) of RHA has been used as a fractional replacement of cement. PVA fiber has been added to this mix at fixed percentage of 0.50% by weight of concrete. 6 mm geometric length of PVA fiber which were aspect with ratio of 428 were used in this research work. In the present research work I did non-destructive and destructive tests after 7 days and 28 days. The values of tests were 10% for RHA and 50% of RCA with fiber fulfills which was PVA which were designed as for the requirement of construction industry. The results show that by adding more amount of RHA and RCA the concrete strength starts decreasing. Tests performed over concrete: Rebound Hammer Test, Flexural Strength Test, Water Absorption Test, Compressive Strength Test, Split Tensile Strength Test, and Ultrasonic Pulse Velocity Test.