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JournalISSN: 0170-0839

Polymer Bulletin 

About: Polymer Bulletin is an academic journal. The journal publishes majorly in the area(s): Polymerization & Copolymer. It has an ISSN identifier of 0170-0839. Over the lifetime, 9575 publication(s) have been published receiving 110875 citation(s).
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Journal ArticleDOI
F. Boran1Institutions (1)
Abstract: The preparation of poly(vinyl alcohol) (PVA) hydrogels was succeeded via the freeze-thawing (F/T) method by varying the synthesis parameter conditions. The swelling capacity and long-term stability of the hydrogels were determined as a function of time at pH 2.1, 5.5 and 7.4 and found to be mainly affected by the synthesis parameter conditions. These studies showed that the swelling ratio generally increased with a low number of F/T cycles (2 and 3), high freezing temperature (− 5 and − 16 °C) and freeze-dried of drying type for all three pH mediums. The dried hydrogels at room temperature were found to be more stable hydrogels. In addition, the drug release studies of salicylic acid as a drug model were investigated at pH 7.4 and displayed controlled release for 120 h. The release kinetic studies obtained from drug release data demonstrated that the PVA hydrogel fits well into the Higuchi model. The release mechanism of PVA hydrogel was also determined as super case II type.

Journal ArticleDOI
Farhang Pazani1, Abdolreza Aroujalian1Institutions (1)
Abstract: Mixed-matrix composite membrane (MMCM) made from a dense selective layer filled with various filler on the top of a porous support layer is an effective method to obtain high gas separation performance compared to the conventional mixed-matrix membrane. In this study, the high CO2-selective Pebax-1657 layer was coated onto the porous PES support layer with desirable mechanical stability, and then graphene nanoplatelets (GNPs) were embedded into Pebax selective layer at different concentrations (below 1 wt%) to evaluate the influence of GNPs on the separation properties of gases such as CO2, O2, and N2 with distinct features under fixed pressure and temperature (4 bar and 25 °C). The prepared MMCMs were characterized by SEM, XRD and FTIR analysis. The single gas separation results showed that the permeability and selectivity of MMCMs were simultaneously increased by GNP loading. The MMCM containing 0.7 wt% GNP considerably improved the CO2 permeability, CO2/N2, and O2/N2 selectivities about 68%, 50%, and 28%, respectively, in comparison with the pure MMCM. This was attributed to the higher aspect ratio of GNPs, which can produce more interaction with Pebax and CO2 gas. Thus, fabrication of the GNP-embedded MMCMs is an effective strategy to improve the gas separation properties.

2 citations

Journal ArticleDOI
Li Wei1, Huali Tang1, Feihua Zou1, Mingzhong Cai1Institutions (1)
Abstract: New aromatic polyamides containing cardo groups and triphenylphosphine oxide structures were synthesized by a heterogeneous palladium-catalyzed carbonylation and condensation of bis(4-(3-iodophenoxy)phenyl)phenylphosphine oxide (BIPPO), aromatic diamines bearing cardo groups, and carbon monoxide. Polycondensations were carried out in N,N-dimethylacetamide under 1 atm of CO at 120 °C in the presence of a magnetically recyclable heterogeneous palladium catalyst and 1,8-diaza-bicyclo[5,4,0]-7-undecene (DBU) and afforded novel aromatic polyamides with inherent viscosities between 0.72 and 0.76 dL/g. All the polyamides were quite soluble in dipolar aprotic solvents and pyridine and could be converted into transparent, flexible, and tough polyamide films by casting from DMAc solutions. These polymers exhibited high thermal and thermooxidative stability with the glass transition temperatures of 237 °C–256 °C, the temperatures at 5% weight loss of 448 °C–465 °C in air. All the phosphorus-containing polyamides self-extinguished as soon as the flame was removed, and the limited oxygen indices (LOIs) of these polymers were in the range of 39%–44%. The polymer films also showed good mechanical properties and high optical transparency.

Journal ArticleDOI
Abstract: In this study, blend of polycarbonate (PC)/polybutylene terephthalate thin films was used. This blend belongs to the class of polymeric solid-state nuclear track detectors. Blend samples were exposed to gamma-rays with different doses (55–355 kGy). The compositional changes, the changes of optical properties, the electrical parameters changes and surface morphology in the gamma irradiated samples were studied. Different techniques were used to study improving the physicochemical properties of the irradiated samples, such as Fourier transform infrared spectroscopy, UV–Visible spectroscopy, LCR Meter Bridge and scanning electron microscope, as well as, the roughness testing. Fourier transform infrared measurements exhibit that the degradation in the polymer chain occurs after irradiation with gamma-rays. This means that some functional groups are the most sensible groups to gamma-rays. UV–Visible spectra of the gamma exposed samples exhibited a shift in the absorbance edge toward the region of higher wavelength. This trend reflects a decrease in the band gap energy, which leads to an increase in the electrical conductivity of the samples. The outcomes of dielectric loss and dielectric constant are sensible parameters for whole frequency range to the changes in the structural and optical behaviors as a result to gamma irradiation. Additionally, the surface changes were discussed.

1 citations

Journal ArticleDOI
TL;DR: It was demonstrated that the huge quantities of bones rejected each year by the cuttlefish processing units from Dakhla city can be valorized by the production of about 77 tons of β-chitin that can be transformed into 60 tons of chitosan (presenting low degree of acetylation and molar masses ranging from 78,000 to 340,000 g/mol).
Abstract: β-chitins are extracted from two different parts of cuttlefish (Sepia officinalis officinalis) bone; the shell and the thin layer. They are then subjected to N-deacetylation reactions to prepare chitosans using the Broussignac or the Kurita process. The physicochemical characteristics of chitins and chitosans are compared to those obtained in the case of squid (Loligo vulgaris) β-chitin. In this work, the role of the source in determining the reaction behavior, during the extraction of chitin and the preparation of chitosan, is confirmed, although it is a β-chitin of two taxonomically close species. In particular, we show that the differences observed can be related to the differences in molar masses of the starting chitins, their crystallinity index and the rates of molecular degradation which accompany the N-deacetylation reactions. Finally, it was demonstrated that the huge quantities of bones rejected each year by the cuttlefish processing units from Dakhla city, alone, can be valorized by the production of about 77 tons of β-chitin that can be transformed into 60 tons of chitosan (presenting low degree of acetylation and molar masses ranging from 78,000 to 340,000 g/mol).

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