Increase In Carboxyl Content Research Articles

Eco‐friendly durable press finishing of cellulose‐containing fabrics

AbstractTo impart easy‐care properties to cellulose‐containing fabrics along with avoiding any harmful effects of formaldehyde on both the health and the environment, attempts have been made to use citric acid (CA) as an ester crosslinking agent along with different catalytic systems in the absence and presence of certain additives. Further, fixation conditions, type of crosslinking agent, as well as type of substrate have been studied. Results revealed that the enhancement in carboxyl content, performance properties, and the decrease in tear strength (TS) as well as in whiteness indices (WI) of the finished fabric samples were increased by increasing CA concentration up to 80 g/L and by raising thermofixation temperature from 140 up to 180°C for 90 s. Inclusion of triethanolamine hydrochloride (TEA. HCl), decreased the carboxyl content, TS, color strength K/S, as well as oily stain release rating (SRR) of the finished fabric samples along with an increase in bound nitrogen (%N), wrinkle recovery angle WRA, and an improvement in WI without affecting the durable press rating (DP). Within the range examined (0–30 g/L), increasing PEG‐600 concentration improved the wet resiliency, TS, as well as WI properties of the finished samples. Increasing DMDHEU ratio in the CA/DMDHEU crosslinking system gave rise to an increase in %N, WRA (dry and wet), DP, as well as in free CH2O of finished fabrics, along with a slight improvement in WI values. On the other hand, the TS, carboxyl content, K/S, SRR values of the finished fabric samples were lower at a higher DMDHEU ratio. Increase in carboxyl content, %N, WRA (dry and wet), DP and SRR, as well as extent of post dyeing (K/S) of the treated fabric samples upon using different ester crosslinking agents followed the descending order: citric acid > pyromellitic dianhydride. The opposite holds true for the TS, and WI values. Among the esterifying catalysts used, and for a given set of finishing conditions, NaH2PO2 · H2O proved to be the most effective one, and the following order of effectiveness may be drawn: NaH2PO2 · H2O > K2HPO4 > Na3–citrate > Na2–tartrate. Inclusion of silicone softener in the finishing formulation brought about an improvement in softeness degree, WRA, %N, DP, TS as well as K/S values along with a decrease in carboxyl content, SRR, and WI values of the treated fabric samples, regardless of the used silicone softener.The performance properties of the finished fabric samples were determined by the type and nature of the substrate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2243–2253, 2002

HNO 3/H 3PO 4–NANO 2 mediated oxidation of cellulose — preparation and characterization of bioabsorbable oxidized celluloses in high yields and with different levels of oxidation

The reaction of cellulose with a mixture of HNO 3/H 3PO 4–NaNO 2 (2:1:1.4, v/v/%w) at room temperature for different time intervals has been investigated to produce oxidized cellulose (OC), a biocompatible and bioresorbable polymer. The results revealed an increase in carboxyl content of OC with increasing reaction time, corresponding to about 8.0, 13.4, 17.4 and 18.4% carboxyl content after 12, 24, 36, and 48 h, respectively. The yield of OC ranged between 75 and 81%. The use of different ratios of HNO 3 and H 3PO 4, (11:1, 4:1, 2:1, 1:1, 1:2, and 1:4; v/v), in the reaction had no significant effect on the carboxyl content and yield of the OC products. All products, as produced, were low crystallinity (27–35%) fibrous materials. The length of fibers decreased with increasing reaction time. After ball milling for 24 h, the length of fibers further decreased and products converted into a fine powder consisting of small fibers and aggregated non-fibrous particles. The degrees of polymerization (DP) of the OC products produced after 12, 24, and 48 h of reaction duration were 81, 63, and 53, respectively. After ball milling for 24 h, the corresponding values changed to 57, 51 and 46. However, no significant change in the crystallinity of the products was noted after ball milling. The TGA results showed the OC products to be less thermally stable than cellulose. The degradation temperature appears to decrease with increasing carboxyl content. In conclusion, the results show that the low crystallinity OC products can be successfully prepared in high yields and with different levels of carboxyl content from cellulose by treatment with a mixture of HNO 3/H 3PO 4–NaNO 2.

Preparation and characterization of saponified delignified cellulose polyacrylonitrile-graft copolymer

Acrylonitrile was graft polymerized onto delignified cellulose using ceric ammonium nitrate as initiator. Polymerization typically yield cellulose-g-polyacrylonitrile containing 45.05g acrylonitrile per 100g sample. The resulting copolymer was saponified with (0.75M) sodium hydroxide. The treatment was carried out at 100°C for different time duration. The extent of saponification was assessed by estimating carboxyl content, nitrogen content, acrylonitrile and acrylic acid before and after saponification. The alkaline treatment results in a decrease in nitrogen content and increase in carboxyl content. Moreover, beside the conversion of cyanide groups to carboxyl groups, alkaline treatment brings about cleavage of ether linkage of the copolymer.The potential value of the saponified modified cellulose is serve as a water absorbance was assessed through measurements of critical properties such as solubility and absorbance of water, saline water and synthetic urine. Also, the property of the prepared sample of swelling to gel was used to absorb water from ethanol–water mixture.

Degradation of lignin in wheat straw during growth of the oyster mushroom (Pleurotus ostreatus) using off-line thermochemolysis with tetramethylammonium hydroxide and solid-state (13)C NMR.

The oyster mushroom (Pleurotus ostreatus) is widely cultivated on wheat straw (Triticum aestivum); however, there is a need to better understand the relationship between the chemical composition of the compost and mushroom growth. Wheat straw was degraded over a period of 63 days by P. ostreatus during which time it was sampled at weekly intervals. Off-line thermochemolysis with tetramethylammonium hydroxide and solid-state (13)C NMR were then used in the molecular characterization of the undegraded wheat straw and the degraded samples. The degraded wheat straw samples had a lower proportion of syringyl- to guaiacyl-derived moieties and cinnamyl- to guaiacyl-derived moieties than the undegraded control. There were increases in both guaiacyl and syringyl acid to aldehyde ratios with composting time, which showed that side-chain oxidation has been mediated by P. ostreatus. The (13)C NMR spectra confirmed the increase in carboxyl content but indicated that the overall lignin and methoxyl contents remained relatively constant, although some nonsystematic variations were observed. The spectra also showed a decrease in amorphous noncellulosic polysaccharides in relation to the crystalline cellulose upon degradation.

Photophysics of 2,6-bis(4′-diethylaminobenzylidene)cyclopentanone in a polymer matrix containing carboxyl groups

The photophysics of a photosensitizer, 2,6-bis(4′-diethylaminobenzylidene)cyclopentanone (DBC) in solvents and polymer matrices containing carboxyl groups is reported. In acetic acid, the fluorescence spectrum of DBC showed two bands of fluorescence with individual lifetimes. Two emitting species were also observed in polymer matrices containing carboxyl groups. The shorter and longer wavelength fluorescence bands are assigned to the emission from DBCs hydrogen bonded (HB) and protonated (PR) with the carbonyl group, respectively. As the concentration of DBC increased, the ratio of PR fluorescence intensity to HB fluorescence intensity increased, and the lifetime of HB fluorescence decreased. The energy level of HB in the excited state is dispersive depending on the magnitude of hydrogen bonding, resulting in the gradual red-shift of fluorescence spectra with the increase of carboxyl content and DBC concentration. Efficient energy transfer was observed from the HB to PR-DBC which acts as an energy trap in the polymer matrix containing carboxyl groups.

13C NMR spectroscopic analysis of soil humic acids recovered after incubation with some white rot fungi and actinomycetes

Culture media containing soil humic acids were inoculated with either white-rot fungi ( Phanerochaete chrysosporium and Trametes versicolor) or actinomycetes ( Streptomyces viridosporus and Streptomyces sp.) and incubated until a loss of about 30% of humic acids had occurred in the growth medium. The humic acids were recovered by the use of a metal chelate affinity procedure and studied by 13C NMR spectroscopy in order to collect more information about the mechanism of attack on humic acids. The spectra resulting from fungal activity were the most modified; however, no important changes in the main constituents of these compounds and no increase in carboxyl content were recorded. The results suggest an unusual degradation process.

Changes in zeta-potentials of amorphous cellulose particles with chitosan salts.

Changes in ζ-potentials of amorphous cellulose and pulp particles by the addition of chitosan salts to suspensions were studied, where amorphous partcles were prepared from microcrystalline cellulose powder, linter cellulose, and softwood and hardwood bleached kraft pulps (SBKP and HBKP, respectively). Chitosan salts with 75 and 85% degrees of deacetylation and with Cl- and AcO-; as counter ions of the amine salts were used. The amounts of chitosan salts required for 0 mV ζ-potentials of amorphous smaples, which originally had ζ-potentials from -24 to -38mV, increased with an increase in carboxyl content of the original cellulose or pulp samples. These ζ-potentials became 0mV except for HBKP by the addition of chitosan salt lower than 0.1% on dry weight of amorphous samples to the suspensions, although HBKP required the addition of chitosan more than 0.2% in some cases. The effects of degrees of deacetylation, counter ions, and cation contents of chitosan salts, used so far, on ζ-potentials of amorphous samples were negligible or very slight. Compared with aluminium sulfate, ζ-potentials of amorphous samples were stable within 1 day after the addition of chitosan salts.

Effect of structure on properties of aromatic polyamides

AbstractPolyamides were prepared by reacting 3,5‐diamino benzoic acid (DAB) and/or 1,3‐bis (3‐amino benzamido) benzene (ABB) with terephthaloyl chloride in N, N‐dimethylacetamide. Five polymer samples having different contents of pendant carboxyl groups were prepared by changing the molar ratios of DAB: ABB in the initial monomer feed as 1: 0 (C), 3:1 (C3 A), 1:1 (CA), 1:3 (CA3), and 0:1 (A). The inherent viscosities of the polymers ranged from 0.198 to 0.478 dL/g. DSC and TG studies indicated loss in weight in the temperature range of 80–200°C due to absorbed moisture. The major loss in weight was observed above 400°C. The anaerobic char yield at 800°C depended on the backbone structure and was found to range from 25 to 40%. The resistivities of polyamide film was determined at 110 and 130°C and was found to decrease with an increase in carboxyl content. The dielectric constant of C and C3A polymer films was determined at frequencies ranging from 100 Hz to 1 MHz and at 110 and 130°C and was found to decrease with an increase in frequency or decrease in COOH content in the backbone.