Vanillin can be obtained from waste of lignocellulosic bioresources with various methods. 1−3 Such vanillin was used as chain extender [divanillin-ethanol amine conjugate (DV-EA)] after its dimerization and further modification with ethanolamine in the synthesis of biobased polyurethane, thereby increasing wt % of biocontents in the final polymer. 1,4-Butanediol often used as a general chain extender in polyurethane synthesis was replaced partially with DV-EA. The generated polyurethane hard segment consists of DV-EA polyol and MDI (methylene diisocyanate) units or 1,4-butanediol and MDI units, respectively. The properties of the DV-EA-based polyurethane were investigated with differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analyzer (DMA), X-ray diffraction spectroscopy (XRD), and universal testing machine (UTM). The results showed that this advanced polyurethane has 128% of Young's modulus and 147% of increased strain compared to those of control, while its strength and thermal stability were maintained. It is expected that this new biobased tetraol may inspire a new perspective of vanillin application in biobased polyurethane synthesis.
Polyurethane (PU) is a versatile polymer used in a wide range of applications. Recently, imparting PU with self-healing properties has attracted much interest to improve the product durability. The self-healing mechanism conceivably occurs through the existence of dynamic reversible bonds over a specific temperature range. The present study investigates the self-healing properties of 1,4:3,6-dianhydrohexitol-based PUs prepared from a prepolymer of poly(tetra-methylene ether glycol) and 4,4′-methylenebis(phenyl isocyanate) with different chain extenders (isosorbide or isomannide). PU with the conventional chain extender 1,4-butanediol was prepared for comparison. The urethane bonds in 1,4:3,6-dianhydrohexitol-based PUs were thermally reversible (as confirmed by the generation of isocyanate peaks observed by Fourier transform infrared spectroscopy) at mildly elevated temperatures and the PUs showed good mechanical properties. Especially the isosorbide-based polyurethane showed potential self-healing ability under mild heat treatment, as observed in reprocessing tests. It is inferred that isosorbide, bio-based bicyclic diol, can be employed as an efficient chain extender of polyurethane prepolymers to improve self-healing properties of polyurethane elastomers via reversible features of the urethane bonds.
Isosorbide (ISB), a nontoxic bio-based bicyclic diol composed from two fuzed furans, was incorporated into the preparation of flexible polyurethane foams (FPUFs) for use as a cell opener and to impart antioxidant properties to the resulting foam. A novel method for cell opening was designed based on the anticipated reversibility of the urethane linkages formed by ISB with isocyanate. FPUFs containing various amounts of ISB (up to 5 wt%) were successfully prepared without any noticeable deterioration in the appearance and physical properties of the resulting foams. The air permeability of these resulting FPUFs was increased and this could be further improved by thermal treatment at 160 °C. The urethane units based on ISB enabled cell window opening, as anticipated, through the reversible urethane linkage. The ISB-containing FPUFs also demonstrated better antioxidant activity by impeding discoloration. Thus, ISB, a nontoxic, bio-based diol, can be a valuable raw material (or additive) for eco-friendly FPUFs without seriously compromising the physical properties of these FPUFs.
The main role of surface sizing of linerboard is to improve surface and strength properties. Since surface sizing solution is applied on once dried web, substantial amount of drying energy is required. Saving of the drying energy associated with surface sizing can be made by increasing the solids content of the starch solution in size press. Therefore, it is highly desirable to develop low viscosity starches for surface sizing. A low viscosity oxidized starch was prepared and compared its effect of surface sizing with a conventional oxidised starch. Results showed increase in solids content of the starch solution decreased evaporation energy and drying time. Low viscosity starch penetrated deeper into paper and this improve various mechanical properties of linerboard.
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