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Highly aligned, tightly packed, single-, double-, and mixed-layer polycarbonate (PC) hollow fibrous membranes were prepared using two-fluid coaxial electrospinning. Polyethylene oxide (PEO) was used as the core, and PC was used as the shell; the PEO was subsequently extracted. The effects of the polymer concentration and spinning voltage on the morphologies and mechanical properties of the membranes were explored. At a PC concentration of 20 wt% and voltage of 8 kV, a hollow fibrous membrane (PC20-8) with a perfectly packed double-layered structure, high alignment of 97%, and distinct pentagonal pores (different from the typical quadrangle pore structure) was prepared. This membrane had the highest Young's modulus and tensile strain, 1.8 GPa and 700%, respectively. The observed results suggest that highly aligned hollow fibrous membranes with favorable mechanical properties, particularly PC20-8, have potential for application in guide conduits for nerves, vascular scaffolds, and biomedical devices.

The chemical resistance of chlorinated hydrocarbons in starch/polyvinyl alcohol (PVA) blends has been investigated using a permeation cell with an in-cell solid phase microextraction (SPME) sampling device. The chlorinated hydrocarbon with a large molecule size or lower polarity was found to be less permeable through the starch/PVA blends. The tensile strength and chemical resistance of chlorinated hydrocarbons decreased with an increase in the starch content of blends. For the starch/PVA blends, the solubility of chlorinated hydrocarbons was inversely proportional to their molecular weight, molar volume and log Kow. The diffusion coefficients and solubility of permeants were proportional to the content of starch in the starch/PVA blends. It is plausible that the blends will be inclined to the starch characteristics as the plasticizer (i.e. glycerin) disrupts the rigidity arrangements of the starch and PVA. The present work provides information on the extent of organic compound permeation through starch/PVA blends for the practical application.

The common biodegradable properties of polymer make them an excellent pair for blending, and the water solubility of polyvinyl alcohol (PVA) makes it easy to mix evenly with the starch. In this study, PVAs with different molecular weights were blended with various compositions of cross-linked starch (CLS) to explore the effects of molecular weight of PVA on the biodegradable characteristics of the PVA/starch blends. Comparing the biodegradability of all the various PVA/starch blends, a PVA was singled out from the PVA/starch blends of higher biodegradability. Further, the chosen PVA was then blended with the acid-modified starch (AMS) to systematically investigate the effects of the modified processing of starch on the biodegradable characteristics of the PVA/starch blends. Differential scanning calorimetry (DSC) analysis of PVA and PVA/starch specimens reveal that the Tm values of PVA/starch specimens reduce gradually as their CLS or AMS contents increase. After the CLS is blended in PVAs of different molecular weights, the tensile strength (σf) and elongation at break (ef) values of (P100S0)G20M1 specimen increase and simultaneously reduce, respectively, as their molecular weights of PVA increase from about 80,000 (PVABF-17) to 120,000 (PVABF-26). The σf and ef values of the PVA/modified-starch blends decrease with an increase in the modified starch contents. The σf values of the PVA/AMS specimens decrease with an increase in the concentrations of hydrochloric acid. Comparing the σf values of the PVA/CLS specimens with those of the PVA/AMS specimens, the σf values of the PVA/CLS specimens are better than those of the PVA/AMS specimens. On the contrary, the ef values of the PVA/AMS specimens are better than those of the PVA/CLS specimens. According to the biodegradability of all the PVA/starch blends, PVA with higher molecular weights displays higher biodegradability. The biodegradability of the PVA/modified-starch blends increase as the modified starch contents of the PVA/modified-starch blends increase. As evidenced by the results of the biodegradability test, the biodegradability of the PVA/modified-starch blends, therein PVA is blended with 1N AMS, shows better biodegradability. The result of bio-reaction kinetics experiment can evaluate the decomposition tendency of the PVA/starch blends up to any biodegradable rate under ambient environment. Using the kinetic model of the first order reaction, it is estimated that 16.20 years and 12.47 years will be needed for the PVABF-17/starch blends, containing 20 and 40% of CLS respectively, to be degraded up to 70% under ambient environment. In addition, it is 1.68 years for the PVABF-26 blends with the 40% 2N AMS under decomposition environment while it is 1.94 years for the 40% 1N AMS. Overall, the decomposition potential of PVA/AMS specimens is better than PVA/CLS specimens. Furthermore, the 1N(26P60AS40)100G20M1 specimen is coincidence the biodegradable material criteria of Environmental Protection Administration (EPA) of Taiwan.

A series of polydimethylsiloxane-containing elastomers (S elastomers) were synthesised from 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (1,4-BD) and polydimethylsiloxane (PDMS). Through TGA analysis, S elastomers exhibited a four-stage degradation. The first and second stages resulted from the degradation of hard segment; the complicated degradation behaviour in the stages is associated with two hard-segment structures in the S elastomers. The third stage was the decomposition of PDMS, in which a cyclosiloxane degradation product was formed; subsequently, at a higher temperature it proved to be macrocyclics, which were degraded in the vicinity of 550 °C. Obviously, the degradation of S elastomers differed from the two-stage degradation of conventional polyurethane. Compared to conventional polyurethane, S elastomers presented better mechanical properties, showing the strength and elongation at break about 5.6~20.6 MPa and 550~830 %, respectively. With the better mechanical properties of S elastomers, nano-structured fibre mats were produced by electrospinning. Fibre morphology was observed by SEM and the effects of processing variables, including solution concentrations and voltages, on the morphology were evaluated.

Polyvinyl alcohol (PVA) and starch are both biodegradable polymers. These two polymers can be prepared as biodegradable plastics that are emerging as one of the environmental friendly materials available now. In this study, after reacting with sodium trimetaphosphate (STMP), modified corn starch was blended with PVA in different ratios by a barbender. Test samples were prepared for mechanical and thermal properties measurements. The surface roughness and morphology of fractured surface of the samples were observed by an atomic force microscopy (AFM) and scanning electron microscope (SEM) measurements. Aqueous degradation by enzyme, water absorption and biodegradability behavior were evaluated for the degradability. The biodegradability of these materials was followed by bio-reactivity kinetics models. Results showed that the addition of modified starch could enhance its water uptake. With an addition of 20 wt% of modified starch, the blend had a maximum weight loss during enzymatic degradation. It was found that the degradability was enhanced with the addition of the starch. Analyzing the results of the biodegradability based on the kinetic models, the growth rate of the microorganism was found to be increasing with the increase of the content of starch in the PVA/starch blends in the first order reaction fashion. In our biodegradability analysis, i.e., based on the China national standards (CNS) 14432 regulations, we estimated the decomposition behavior based on the mentioned first order reaction. We found that the PVA/starch blends would take 32.47, 16.20 and 12.47 years to degrade by 70% as their starch content 0, 20 and 40 wt%, respectively.

This study elucidates the behaviour of heavy metals in slag produced from four different sewage sludge ashes mixed with municipal solid waste incinerator fly ash and then co-melted. Experimental results indicate that sewage sludge ashes consisted of SiO 2, CaO, and Al2O3. Fly ash consisted of CaO, Na2O and SO3. The speciation of sewage sludge ashes indicates that the ashes contained quartz and AlPO4. The speciation in fly ash consisted of anhydrite, microcline, calcium chloride, sylvite and halite. The leaching behaviours of sewage sludge ashes met the Taiwan Environmental Protection Administration’s regulatory standards. The fly ash had high concentrations of Zn and Pb; however, the leaching of these metals was low. The major components of synthetic slags were SiO2 (33.5—54.0%), CaO (21.4—36.7%), and Al2O3 (8.1—15.7%). The X-ray diffraction patterns of co-melted slags demonstrate that the slags contained significant amounts of glass. Most heavy metals can be fixed in a net-like structure; thus, they can not be extracted easily. The toxicity characteristic leaching procedure (TCLP) leaching concentrations for target metals in all slags met the Taiwan Environmental Protection Administration’s regulatory standards.

A series of blends of poly(lactic acid) (PLA) and poly(e-caprolactone) (PCL) with different mass ratio were prepared by means of the melt blending method to study their crystallization, miscibility, morphology, and thermal and mechanical properties. The result of DSC tests showed that the melting temperatures of PLA and PCL shifted toward each other, and that the largest shift appeared at the PLA70PCL30 blend. This result reveals that the PLA70PCL30 blend gives the strongest interaction intensity among the blends. Combined the result of dynamic mechanical analysis and SEM morphologies, it was found that PLA and PCL form a partial miscible blend, in which an amount of amorphous PCL (amorphous PLA) is dissolved in the PLA-rich phase (PCL-rich phase), leading to a depression of the Tg. value. The polarized optical micrographs showed that PCL can serve as a nucleating agent to promote PLA crystallization in the PLA/PCL blend. Moreover, the PLA70PCL30 blend gave the largest growth rate of PLA spherulite. Final...

The article describes a systematically investigations of the blending effects of waste polypropylene (PP), fly ashes (FA) on the physical and chemical properties of the PP/fly ashes blends. In addi...

The aim of this study was to investigate the characteristics and mechanism of the degradation of poly(siloxane-urethane) (PSiU) copolymers by thermogravimetric analysis (TGA) and TGA coupled with Fourier-transform infra-red spectroscopy (TG–FTIR). The PSiU copolymers consisted of 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (1,4-BD), and OH-terminated polydimethylsiloxane (PDMS). In TGA they exhibited a two-stage degradation at 250–650 °C. The two stages of degradation have been found to comprise eight degradation steps and two interchange reactions, as revealed by TG–FTIR analysis. The main decomposition products have been identified as CO 2 , tetrahydrofuran, cyclosiloxane, and macrocyclic species. In addition, the effects of hard segment content (HSC) on the degradation and thermal stability of PSiU copolymers have been investigated by means of TG and DTG curves; notably, a stability region at 410–470 °C is caused by the cyclosiloxane, as verified by TG–FTIR.

Municipal solid waste incinerator fly ash (MSWIFA) is considered a hazardous material because of its high content and leachability of heavy metals and soluble salts. In this study, leaching and the...

In this study, different fractions of fly ashes, poly (tetramethylene glycol) (PTMG), and excess 4, 4′-diphenylmethane diisocyanate (MDI) were added into a reactor to form the polyurethane (PU)/fly ashes blend. It is evident that heavy metals can be encapsulated in PU foam, which was shown by the results of a toxicity characteristic leaching procedure (TCLP) test. After the tensile strength test, the elongation test, and the hardness test, the physical and chemical properties of the PU/fly ashes blend were acceptable for commercial applications. Meanwhile, based on the leaching criteria of Environmental Protection Administration (EPA) of Taiwan, comparing the new PU/fly ashes blended with 18% fly ashes and PU/fly ashes blended in ambience at room temperature for 1 year's time revealed both blends to function effectively in the tests. The results from the weatherability test illustrate that the maximum percentage of fly ashes allowed in the blends was 18%. Therefore, fly ashes blended with PU foam was a ne...

This study describes the preparation and characterization of new ionomer blend membranes containing sulfonated poly(ether imide) (SPEI) and poly(ether sulfone) (PES). Thermogravimetric analysis indicated that the obtained blend membranes were more thermally stable than the parent SPEI. As the PES content increased, the extent of membrane swelling by water decreased, and the oxidative stability was significantly increased by the specific interactions between PES and the sulfonic acid groups. Under both dry and wet conditions, the tensile strength of all the blend membranes was larger than that of the pure SPEI membrane and Nafion 112 because of the reinforcing effect of PES. Scanning electron microscopy and atomic force microscopy indicated that the blend membranes became more compact as the PES content increased, and this reduced the methanol diffusion. The blend membranes with PES contents below 50% showed adequate proton conductivity. The lower permeability of the blend membranes compared with the Nafion 112 membrane resulted in higher methanol resistance. This considerable reduction in methanol crossover revealed the feasibility of the blend membranes as promising electrolytes for direct methanol fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

This investigation examines characteristics of sulfonated polyether imides (SPEI) with various ion exchange capacity values (IEC) and completes previous work to enable its blends to be adopted as polyelectrolyte in direct methanol fuel cells (DMFC). Polyether imides (PEI) were sulfonated by using chlorosulfonic acid as the sulfonating agent and chloroform as the solvent. The structure of SPEI was observed by FTIR and 1H NMR. The sulfonate or sulfonic acid content of the polymers, expressed as a number per repeat unit of the polymer, was accurately determined by elemental analysis and conductometric titration. Physical properties such as solubility, intrinsic viscosities, thermal stability, and glass transition temperature (Tg) were studied for both PEI and SPEI. TGA-FTIR verified that sulfonic groups, attached to the aromatic ring in the PEI backbone, are split at 230–350°C, but the main-chain splitting temperature of SPEI is similar to that of pure polymer. The sulfonated samples exhibited good solubilities and increased glass transition temperatures (Tg values) as degree of sulfonation (DS) increased; two Tg values were detected when IEC was sufficiently high. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Sanitary landfilling of municipal solid wastes (MSW) combined with incinerated residuals is a disposal method specific to Taiwan. The purpose of this study was to explore the influences that adsorption, desorption, and biological reactions in landfilling may have on the quality of leachate. Not only did different combinations and the stratification of waste have to be considered, but anaerobic and semiaerobic landfilling have also been simulated. COD concentrations of leachate were processed by using a numerical method to get a simulation model for the estimation of variations in the organic pollutants in the leachate. The intensities of leachate from both semiaerobic and anaerobic landfilling, were also explored with this model. Comparing the simulation with the experimental data, we found that the degradation of the leachate quality was approximately similar for both type of data.

Two series of blends, O-PP15 and O-PP35, were prepared by mixing polypropylene (PP), luminescent powders (SrAl2O4: Eu2+, Dy3+) of 15 and 35 μm average particle diameter, and hydrophobic dispersant at about 190°C in the Brabender mixer. The effect of amounts and diameter of luminescent powders on the physical properties of PP material were discussed herein. The luminescence and afterglow time tests indicated that the initial luminescence of all blends increased with the luminescent powders amounts. O-PP35 blends showed lower afterglow luminance than O-PP15 blends at low luminescent powder amounts. The melting and crystallization temperatures of the blends appeared at 152–168°C and 87–103°C, respectively. The blends displayed peaks attributable to a α crystal structure at 2θ = 18°–19°. The β crystal structure was only evident from its characteristic 2θ peak at 15°–16° in the WAXD pattern of the O-PP35 blends with high luminescent powder amounts. All of the blends had lower tensile strengths. However, the improvement in the luminescent powder distribution was evident from the SEM images after adding hydrophobic dispersant. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Incineration of municipal solid wastes (MSW) is the main method of waste management in Taiwan. Although the incineration of MSW processes the solid wastes at 850–950 °C and destroys most of the organics, the content of incineration ashes is still a problem for landfill. Moreover, acid precipitation is much worse than before in Taiwan, especially in the northern areas. For instance, the occurrence probabilities of acid precipitation measured from 1991 to 1998 in Taipei increase from 73% to 85%. Therefore, it is more important to get a series of data that will help explore the influence of acid precipitation during disposal on characterization of pollutants than to analyze the ash properties after the incinerators have been constructed and regularly used. In this investigation, the disposal site of incineration ashes is simulated in laboratory by test columns. An irrigation experiment is taken to simulate the acid precipitation at room temperature. In order to explore the exact influence on leachate quality of the main chemical composition of acid precipitation, columns are migrated with different concentrations of sulfate in acid precipitation. This investigation showed that the sulfate concentration of acid precipitation has an increasing effect on the accumulative release of heavy metals, such as Zn, Pb and Cu, from leachate. The sulfate concentration of acid precipitation, however, will not influence the trend of chemical oxygen demand (COD), biochemical oxygen demand (BOD 5 ) and total organic carbon (TOC) in the leachate release.