Films properties of QPM corn starch with Delonix regia seed galactomannan as an edible coating material.

Plant-based polysaccharides are considered a good alternative for obtaining edible films and coatings. In this research the objective was to determine the physicochemical characteristics of corn starch obtained from QPM Sac-Beh (SBCS) and Delonix regia galactomannan (DRG) and use them to produce films. Films were elaborated from 1 %(w/v) film-forming solutions (FFS) with SBCS:DRG 1:0, 1:1, and 0:1 ratio. Some films were prepared with glycerol 0.4 %(w/v) and vanillin 0.1 %(w/v). SBCS and DRG were characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. SBCS presented low crystallinity which agrees with a low gelatinization ΔH observed. The SBCS:DRG 1:0 FFS without glycerol did not form films; however, DRG addition allows film formation. It was also found that glycerol addition reduced tensile strength to 10.3 MPa, from 41.3 MPa. The lowest water vapor permeability was found in films with 1:1 SBCS:DRG and 0.1 %(w/v) vanillin. This formulation was used to coat D'Anjou pears. This coating conserved the pears' color for 24 days while the control ones started to get a brown color on day 6. Based on the results obtained, FFS elaborated with 1:1 SBCS:DRG and 0.1 %(w/v) vanillin had potential use as edible film material for coating on climacteric fruits preservation.

Evaluation of Organofunctionalized Polydimethylsiloxane Films for the Extraction of Furanic Compounds.

Hybrid membranes with three different thicknesses, PMDS_C1, PMDS_C2, and PMDS_C3 (0.21 ± 0.03 mm, 0.31 ± 0.05 mm, and 0.48 ± 0.07 mm), were synthesized by the sol-gel method using polydimethylsiloxane, hydroxy-terminated, and cyanopropyltriethoxysilane. The presence of cyano, methyl, and silicon-methyl groups was confirmed by FTIR analysis. Contact angle analysis revealed the membranes' hydrophilic nature. Solvent resistance tests conducted under vortex and ultrasonic treatments (45 and 60 min) demonstrated a preference order of acetonitrile > methanol > water. Furthermore, the membranes exhibited stability over 48 h when exposed to different pH conditions (1, 3, 6, and 9), with negligible mass losses below 1%. The thermogravimetric analysis showed that the material was stable until 400 °C. Finally, the sorption analysis showed its capacity to detect furfural, 2-furylmethylketone, 5-methylfurfural, and 2-methyl 2-furoate. The thicker membrane was able to adsorb and slightly desorb a higher concentration of furanic compounds due to its high polarity provided by the addition of the cyano groups. The results indicated that the membranes may be suitable for sorbent materials in extracting and enriching organic compounds.

Preparation and Characterization of Strongly Sulfonated Acid Block and Random Copolymer Membranes for Acetic Acid Esterification with 2-Propanol.

In this paper, we report the synthesis of block and random copolymers of 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and methyl methacrylate (MMA), with different AMPS feed ratios. These solution-processable copolymers with strongly sulfonated acid groups resulted in membranes with tunable ion exchange (IEC) and water absorption capacities. AFM images confirmed the microphase separation of PAMPS-b-PMMA-1:1 block copolymer membrane, annealed under the appropriate conditions. The resulting copolymers from the random combination of a 1:1 molar ratio of AMPS and MMA monomers are effective at enhancing the esterification conversion of acetic acid, when compared with a reaction catalyzed by PAMPS-b-PMMA block copolymers and the previously studied catalytic membranes. With the PAMPS-co-PMMA-1:1 membrane, the esterification reaction using acetic acid achieved 85% isopropyl acetate. These results are closely correlated with the increase in IEC (2.63 mmol H+g-1) and the relationship between weight loss (20.3%) and swelling degree (68%) in 2-propanol.

New Poly(imide)s Bearing Alkyl Side-Chains: A Study on the Impact of Size and Shape of Lateral Groups on Thermal, Mechanical, and Gas Transport Properties.

A set of five new aromatic poly(imide)s (PIs) incorporating pendant acyclic alkyl moieties were synthesized. The difference among them was the length and bulkiness of the pendant group, which comprises of linear alkyl chains from three to six carbon atoms, and a tert-butyl moiety. The effect of the side group length on the physical, thermal, mechanical, and gas transport properties was analyzed. All PIs exhibited low to moderate molecular weights (Mn ranged between 27.930-58.970 Da, and Mw ranged between 41.760-81.310 Da), good solubility in aprotic polar solvents, except for PI-t-4, which had a tert-butyl moiety and was soluble even in chloroform. This behaviour was probably due to the most significant bulkiness of the side group that increased the interchain distance, which was corroborated by the X-ray technique (PI-t-4 showed two d-spacing values: 5.1 and 14.3 Å). Pure gas permeabilities for several gases were reported (PI-3 (Barrer): He(52); H2(46); O2(5.4); N2(1.2); CH4(1.1); CO2(23); PI-t-4 (Barrer): He(139); H2(136); O2(16.7); N2(3.3); CH4(2.3); CO2(75); PI-5 (Barrer): He(44); H2(42); O2(5.9); N2(1.4); CH4(1.2); CO2(27); PI-6 (Barrer): He(45); H2(43); O2(6.7); N2(1.7); CH4(1.7); CO2(32)). Consistent higher volume in the side group was shown to yield the highest gas permeability. All poly(imide)s exhibited high thermal stability with 10% weight loss degradation temperature between 448-468 °C and glass transition temperature between 240-270 °C. The values associated to the tensile strength (45-87 MPa), elongation at break (3.2-11.98%), and tensile modulus (1.43-2.19 GPa) were those expected for aromatic poly(imide)s.

Effect of Sulfonic Groups Concentration on IEC Properties in New Fluorinated Copolyamides.

Seven aromatic polyamides and copolyamides were synthesized from two different aromatic diamines: 4,4'-(Hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (HFDA) and 2,4-Aminobenzenesulfonic acid (DABS). The synthesis was carried out by polycondensation using isophthaloyl dichloride (1SO). The effect of an increasing molar concentration of the sulfonated groups, from DABS, in the copolymer properties was evaluated. Inherent viscosity tests were carried out to estimate molecular weights. Mechanical tests were carried out under tension, maximum strength ( σ max), Young's modulus (E), and elongation at break (εmax) to determine their mechanical properties. Tests for water sorption and ion exchange capacity (IEC) were carried out. Proton conductivity was measured using electrochemical impedance spectroscopy (EIS). The results indicate that as the degree of sulfonation increase, the greater the proton conductivity. The results obtained showed conductivity values lower than the commercial membrane Nafion 115 of 0.0065 S cm-1. The membrane from copolyamide HFDA/DABS/1S0-70/30 with 30 mol DABS obtained the best IEC, with a value of 0.747 mmol g-1 that resulted in a conductivity of 2.7018 × 10-4 S cm-1, lower than the data reported for the commercial membrane Nafion 115. According to the results obtained, we can suggest that further developments increasing IEC will render membranes based on aromatic polyamides that are suitable for their use in PEM fuel cells.