► The alginate content was studied on properties of aqueous polyurethane dispersions. ► Excellent miscibility was shown on the compositions of polyurethane and alginate. ► The morphology of alginate ...in polyurethane matrix was shown as particulate with different sizes. ► The presence of alginate in microstructure was determined by sodium peak in EDX.
A series of aqueous polyurethane dispersions were synthesized by the reaction of polytetramethylene glycol and isophorone diisocyanate, extended with dimethylol propionic acid. Their chemical structures were characterized using FTIR, 1H NMR, and 13C NMR, and thermal properties were determined by DMTA. Then, a number of aqueous polyurethane dispersions–sodium alginate (PUD/SA) compositions were prepared by addition of sodium alginate solution with different concentrations into the aqueous polyurethane dispersion. Characterization of chemical structure and thermal properties of these blends were performed by FTIR, EDX and DMTA, respectively. The morphology of the alginate in polyurethane matrix was studied by SEM. The hydrophilicity of the prepared samples decreases by increasing the content of sodium alginate in blends. These observations were attributed to the increase of hydrophilicity of the blends as a consequence of addition of hydrophilic carboxylate, hydroxyl and ether functional groups of the alginate to them.
Chitin the second most abundant polysaccharide is synthesized by an enormous number of living organisms including fungi and insects. These biopolymers have found many applications in different areas ...such as: packaging material, membrane for removal of metal ions, dyes and pigments in waste water engineering; anti-cholesterol, fat binding, preservative and food additive in food industry; seed and fertilizer coating, controlled agrochemical release in agriculture; surface treatment, photographic paper in pulp and paper industry; moisturizer, body creams and lotions in cosmetics and toiletries. It has also found wide applications in biomedical such as tissue engineering, drug delivery, wound dressing, scaffolds, cancer diagnosis, etc. The majority of these versatile applications are coming of its non-toxicity, biocompatibility and biodegradability. Chitin is also easily processed as gel, membrane, and nanofiber. This review emphasizes an extensive bibliography of recent basic and applied research and investigations on the aspects of this interesting biopolymer including the recovery, preparation, modification and application of chitin and its derivatives and related compounds. A new class of biocompatible and biodegradable chitin-based polyurethane (PU) elastomer was also introduced and reviewed in this study and it was found that by incorporation of chitin into the PU elastomer backbone, biocompatibility and degradation rate of the final elastomer improved. PUs are one of the synthetic biocompatible polymers with excellent physical and mechanical properties. Combination of this polymer with chitin resulted to a new tailor-made biocompatible and biodegradable polymer with improved properties. These polymers have potential applications in various applications including biomedical.
Waterborne polyurethane/butyl acrylate hybrids based on dimethylol propionic acid (DMPA) and
N
,
N
-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt (BES sodium salt) were successfully ...synthesized. The samples with a weight ratio of 70% waterborne polyurethane and 30% butyl acrylate monomer were prepared by radical copolymerization. Synthesis of the WPUA-DMPA and WPUA-BES was approved by
1
H NMR spectroscopy. Also, properties of the samples such as morphology, thermal stability, mechanical properties, contact angle, hardness, abrasion, and chemical resistance were investigated. The results showed that the synthesized waterborne polyurethane/acrylate hybrid based on BES had better characteristics in comparison with DMPA-based because of stronger chemical bonding, smaller particles, and good particle distribution as SEM analysis verified. Generally, the results illustrated that the sample with the sulfonated anionic center was time-saving which was due to the elimination of the neutralization step by TEA. Eventually, WPUA-BES became more economical and stronger than the other sample.
Graphical abstract
In this work, the effects of changing molecular weight of polyol (2000, 3000, and 4000) and block ratio as well as deformation amplitude on thermal, structural, and shape memory properties of ...polyester urethanes based on diphenylmethane diisocyanate, polycaprolactone diol, and 1,4-butanediol were investigated. Fourier transform infrared spectroscopy was used to check the accomplishment of the polyurethanes synthesis. Thermal, structural, and shape memory properties of synthesized SMPUs were measured using differential scanning calorimetry, wide angle X-ray diffraction, and tensile cyclic tests, respectively. It was found that as the crystallinity of soft segments increased, the ability of the samples in fixation of temporary shape was higher. On the other hand, the shape recovery was dominated by the hard segment content and there was a minimum critical HSC for the samples to show appropriate shape memory effects.
The aim of this study was to investigate polyurethane foams (PUF) properties obtained from crude glycerol (CG) and polyethylene glycol (PEG) based liquefaction of sawdust. The four types of foam were ...prepared by producing polyols from different weight loadings of PEG to CG as the liquefaction solvent. The produced polyurethane foams showed densities from 0.042 to 0.08 g/cm
3
and compressive strengths from 200 to 311 kPa. The foams obtained from CG/PEG based liquefaction, had more uniform and regular cell structure than foams derived from liquefaction by CG. Also with the increasing percentage of PEG to CG in liquefaction, closed cell content of the synthesized foams increased and the size of cells decreased. The thermal conductivity of the produced foams was between 0.031 and 0.040 W/m K. Foams produced from liquefaction by binary solvent had lower thermal conductivity. However all foams showed approximately similar thermal degradation curves; maximum thermal decomposition temperature was seen for the foam produced from higher weight ratio of PEG to CG in liquefaction. PU foams produced from PEG/CG based liquefaction process had improved properties over from foams derived from sawdust liquefaction by CG.
Polyethylene terephthalate is a linear thermoplastic polyester. Different grades of this polymer are used in various industries with a wide range of molecular weights and the manufacturing of ...beverage bottles. Due to its abundant waste products, it has become a problem for the environment. In this research, polyethylene terephthalate was reacted with ethylenediamine, butylenediamine, and hexamethylenediamine at a ratio of polymer 1 to 6 of each reactant. Polymer was then reacted with hydrazine hydrate in different molar ratios at various time intervals. The effect of catalyst concentration on the reaction yields was studied. It was observed, that with the increase of aliphatic groups in the structure of the final product its melting point was lower which might have been due to the presence of more flexible methylene groups in the final structure.
•Plasma treatment of polypropylene was performed using both O2 and Ar atmospheres.•Plasma treated polypropylenes were analyzed by both FTIR and AFM techniques.•Polyurethane-urea ionomer was found as ...an efficient coating for treated polypropylene.•This coating increases surprisingly adhesion strength of oxygen treated polypropylene.
In present research, polypropylene (PP) was selected as a model nonpolar substrate for chemical modification using plasma. In the first step, the PP samples were treated using oxygen and argon atmospheres, individually. The prepared samples were analyzed using both FTIR and AFM techniques. The output of these techniques revealed that the carbonyl, carboxylic acid and its derivatives have been formed on the surface of PP. Afterward, a series of aqueous polyurethane-urea dispersions were synthesized as the novel polar coating for modified nonpolar polymers and characterized by different techniques including FTIR, DSC, TGA, mechanical properties and contact angle. Finally, the plasma treated samples were coated by prepared polyurethane ionomer. The results of pull-off analysis confirmed the significant role of the polyurethane as an extremely polar coating to create hydrogen bonding with functional groups on the surface of treated PP. The adhesion strength of polypropylenes increased from 0.04MPa to 0.61MPa for neat and oxygen-based plasma treated samples, respectively.
Biodegradable polyurethane elastomers with potential for biomedical application as non-absorbable sutures with improved hydrophobic properties were synthesized by the reaction of poly(ε-caprolactone) ...(PCL) and 4,4′-diphenylmethane diisocyanate (MDI), extended with different mass ratio of chitin and 1,4-butane diol (BDO). Their molecular engineering and structural transition due to the changes of hydrogen bonding was confirmed by using FT-IR,
1H NMR and
13C NMR. Involvement of chitin was evidenced by the appearance of new signals in both
1H NMR and
13C NMR spectra, and very strong peak at 1724
cm
−1 in FT-IR spectra. From the results, it was concluded that the reaction of the urethane group occurred mainly at C6
OH group of chitin in which strong intermolecular and intersheet hydrogen bonds are involved. Contact angle and surface tension measurement of the synthesized polyurethane as a function of chitin contents were investigated. Optimum hydrophobicity was obtained from elastomer extended with chitin in comparison to elastomers extended with BDO. The surface free energy was also affected by chemical composition of the final PU. Structure–property relationship for prepared elastomers showed that the main determining factors were hydrogen bonding, hydrophobicity and content of chitin in polyurethane backbone.
A novel type of polyurethane elastomer (PUE) containing nanocomposites of sodium alginate thiacalix4arene macrocycles including sodium alginate-thiacalix4arene and sodium alginate-tetra-sulfonated ...thaiacalix4arene (SA-TSTCA) was prepared. The key role of these nanocomposites merged into polyurethane elastomers is to function as chain extenders. To provide profound insight into the structural, thermal, mechanical, morphological and hydrophilic properties of the samples, several techniques were employed, namely Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Also the results were compared with the results of polyurethane elastomer based on glycerol (Gly) as chain extender. The results showed that the samples extended with nanocomposites as chain extender have better thermal and mechanical properties and between them the PUE containing SA-TSTCA showed higher thermal and mechanical properties. Furthermore, these elastomers have been used as adsorbent for removal of Malachite green (MG) for investigation of the effect of sulfonated groups introduced on the chain extender. The results revealed that SA-TSTCA-based polyurethane elastomer nanocomposite could well adsorb Malachite green from aqueous media by a batch adsorption method. The pseudo-first-order and pseudo-second-order kinetic models were employed to provide an in-depth study of the adsorption capacity of MG, suggesting that its adsorption onto PUE/SA-TSTCA elastomer was in accordance with pseudo-second-order kinetic process. A possible mechanism of adsorption was suggested where π–π stacking interactions, H-bonding interaction and electrostatic attraction controlled the MG adsorption.
Cellulose acetate (CA)/Graphene oxide (GO) nanocomposite membrane was prepared by phase inversion method. GO nanosheets were added to CA matrix with the aim of improving seawater desalination ...performance of asymmetric CA reverse osmosis (RO) membrane and enhancing mechanical and thermal stability. GO with grain size of 2.7 nm was synthesized through modified Hummer method and dispersed in CA matrix to prepare GO/CA nanocomposite membranes. The membranes were fabricated by casting of GO/CA onto a polyester fabric. The results showed that the GO concentrations would affect the morphology, hydrophilicity, porosity, roughness, mechanical strength and thermal stability of membranes. Incorporation of GO into the CA matrix changed the porosity structure from finger-like to sponge-like. Hydrophilicity nature, storage modulus and thermal stability of CA membranes were greatly improved with incorporation of 1 wt% GO. In addition, synthetic seawater salt rejection of CA membrane modified with 1 wt% GO at 25 bar was 1.8 times higher than that of pristine CA membrane, while flux of CA membrane exhibited small reduction with the presence of 1 wt% GO.
•Graphene oxide improved mechanical strength of cellulose acetate membrane.•Graphene oxide improved thermal stability of cellulose acetate membrane.•Porosity structure of cellulose acetate membrane was changed with graphene oxide.•Graphene oxide noticeability increased Salt rejection of cellulose acetate membrane.
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