Diethylaminoethyl cellulose–epoxide reactions

Reactions of various monoepoxides and diepoxides with diethylaminoethyl (DEAE) cellulose in the absence and presence of external catalysts have been studied. In the absence of additional catalysts, many epoxides which did not react with the unmodified cotton reacted with DEAE-cotton. Others, which reacted with unmodified cotton in the presence of external bases, imparted different properties when catalyzed by the builtin tertiary amino groups of DEAE-cotton. For example, epichlorohydrin reacted with DEAE-cotton to produce a fabric with excellent conditioned recovery, good wet recovery, and strong-base anion exchange properties. The same epoxide imparted only wet crease recovery to cotton when the reaction was catalyzed by external bases. Phenyl glycidyl ether and styrene oxide reacted with DEAE-cotton to produce a fabric with twentyfold improvement in resistance to flex abrasion. With 8% aqueous NaOH as an external catalyst, the DEAE-cotton displayed greater reactivity with all epoxides than did the unmodified fabric. DEAE-cotton–diepoxide reactions with added base catalyst generally resulted in a decrease in the conditioned recovery angle and an increase in the wet recovery angle. When Zn(BF₄)₂ was used as an additional catalyst, again the DEAE fabrics displayed the greater reactivity toward the monoepoxides; but the unmodified cotton was more reactive toward the diepoxides than was the DEAE-cotton. The Zn (BF₄)₂–monoepoxide-treated DEAE fabrics had higher wet recovery angles but lower dry recovery angles than the corresponding epoxide-finished control cottons. Butadiene diepoxide was the only diepoxide investigated which imparted higher dry recovery angles to the DEAE-cotton than to the unmodified cotton control in the presence of Zn(BF₄)₂. Tertiary amino groups in DEAE-cottons act as an internal catalyst for the opening of the oxirane rings, direct the site for reaction in the absence of additional catalysts, and react with some epoxides to form quaternary nitrogen groups.     

Flame retardancy for cotton cellulose treated with H3PO3

The flame retardancy of cotton fabrics has been improved with treatment of phosphorous aqueous solution. In this study, cotton cellulose is treated with simple treatment and benign chemicals including an aqueous H₃PO₃ solution dipping and heat annealing. The flame retardancy of the H₃PO₃ treated cotton fabrics is enhanced to the degree that it is non‐flammable. Thermogravimetric analysis results show that the residue increased up to about 50% at 800 °C by the treatment. Scanning electron microscopy exhibit some disconnection of fibers and the fibers are fragile. X‐ray diffractometry reveal little damage to the crystalline structure of cellulose. Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy show some portion of the added H₃PO₃ reacted with cellulose components to be phosphorylated and dehydrated. The resulting data and analysis demonstrate that these dehydrated and phosphorylated moieties formed by treatment of phosphorous solution help accelerate the formation of char components, resulting in improved flame retardancy of cellulose materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46497.     

Flame-retardant cotton fabrics by reaction of cellulose with phosphorus trichloride–DMF adduct

Cotton sateen fabric was found to react with the 1 : 2 adduct of phosphorus trichloride and N,N-dimethylformamide (DMF) in DMF or DMF—chloroform solutions at room temperature. During this reaction, the fabric acquired flame resistance. The introduction of as little as 1.2% phospohorus and 0.4% nitrogen, achieved at adduct concentrations as low as 2–5% in reaction times of 5–30 min, was sufficient to impart a useful level of flame retardancy. The effect of the adduct concentration, reaction time, and wash procedures on the flame resistance and other properties of the resultant cotton fabrics was studied. Moderate increases in the wet and dry wrinkle recovery were imparted by the treatment, but the use of high concentrations of adduct were somewhat detrimental to the tensile strength of the fabric. However, adduct concentrations of 20–25% produced a rather durable finish which passed the standard vertical flame test after 20 home launderings. Gradual loss of flame resistance during repeated laundering is attributable to ion exchange properties gradually acquired by the fabric. Based on analytical and in frared spectral data, the initial reaction of cellulose with the PCl₃—DMF adduct is thought to involve elimination of one mole of DMF to form cellulose? O? P linkages, as well as some cellulose crosslinking via a second formimidate group of the adduct. Gradual hydrolysis during multiple launderings apparently yields cellulose acid phosphates responsible for the calcium ion uptake and decrease in flame resistance.     

Reactions of halogenated 1,2-epoxypropanes and diethylaminoethyl cotton

Diethylaminoethyl (DEAE)-cotton has been reacted with epichlorohydrin (1,2-epoxy-3-chloropropane) neat, in alcoholic solvents, and in aprotic solvents at temperatures ranging from 25 to 95°C. Fabric properties and electron micrographs of fibers removed from these chemically treated DEAE cottons have been compared with those obtained when DEAE-cottons were treated under similar conditions with other halogenated 1,2-epoxypropanes, and with 1,2-epoxy-4,4,4-trichlorobutane. For comparative purposes, epichlorohydrin was reacted with an aminized cotton containing primary amine groups, with cotton containing quarternary ammonium groups, and with DEAE-cottons in which the tertiary amine groups had been quaternized. For reaction at 95°C with net epichlorohydrin, greatest increase in conditioned wrinkle recovery was observed with DEAE-cottons. Only with DEAE-cottons were the add-ons and recovery angles imparted by epichlorohydrin affected by the anion associated with the amine groups. None of the halogenated 1,2-epoxypropanes reacted with unmodified cotton in the absence of a basic catalyst. Those that reacted with unmodified cotton in the presence of an external base catalyst did not improve conditioned recovery angles. The mono-, di-, and trichloro-1,2-epoxypropanes all increased the conditioned and wet wrinkle recovery of DEAE-cotton when reacted neat at 95°C. The type of oxirane ring opening of epoxypropanes was shown to be influenced by the degree of chlorination of the carbon alpha to the ring. Both primary amine groups and quaternary amine groups catalyzed the epichlorohydrin–cellulose reaction. Dilution of epichlorohydrin with alcohols or decreasing reaction temperature lowered add-ons and improvements in wrinkle recovery properties. Use of aprotic solvents for the DEAE-cotton-epichlorohydrin reaction gave finished cotton fabrics having only high wet wrinkle recovery properties.     

Flame-retardant properties and thermal behavior of selected flame-retardant cotton fabrics

The flame-retardant properties and the thermal behavior of cotton cellulose finished with THPC-amide, THPOH-amide, THPOH-NH₃, and THPC-cyanamide were investigated before and after five washes. Phosphorus and nitrogen content, N/P ratios, and total add-on of finish were determined. Flammability properties were evaluated by the 45°C angle, the vertical strip, and oxygen index tests. Differential scanning calorimetry and thermogravimetric analysis were used to study the thermal behavior of the fabrics during pyrolysis. Infrared spectra of samples before pyrolysis and at significant points in the pyrolysis reaction were used to obtain further information regarding the pyrolysis reaction. The THPC-amide, THPOH-amide, and THPC-cyanamide finishes appeared to react in a similar manner to impart flame-retardant properties to the fabrics. During pyrolysis, the finished fabrics apparently decomposed first by an acid catalyzed dehydration and chain breakdown. The second step of the pyrolysis probably involved phosphorylation of the C-6 hydroxyl of the anhydroglucose unit occurring around the temperature range of 345°–350°C. The final step was char formation. The THPOH-NH₃ finished fabric decomposed with a strong exothermic reaction under nitrogen which suggested that the reaction was initiated by a base catalyzed dehydration and chain breakdown. This seemed to be followed by phosphorylation at the C-6 hydroxyl of the anhydroglucose units and then char formation. An inverse relationship between ΔH and the residue remaining after pyrolysis was observed. ΔH was also linearly related to the N/P ratios. All of the fabrics except the TPHC-cyanamide-finished fabric had good flammability properties before and after laundry.     

Combination of a hydroxy‐functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: Part I. The chemical reactions

Multifunctional carboxylic acids, such as 1,2,3,4‐butanetetracarboxylic acid (BTCA), have been used as crosslinking agents for cotton cellulose to produce wrinkle‐resistant cotton fabrics and garments. Polycarboxylic acids were used to bond hydroxy‐functional organophosphorus oligomer to cotton, thus imparting durable flame retarding properties to the cotton fabric. This research investigated the chemical reactions between the hydroxy‐functional organophosphorus compound and BTCA on cotton. BTCA crosslinks cotton cellulose through the formation of a 5‐membered cyclic anhydride intermediate and esterification of the anhydride with cellulose. In the presence of the organophosphorus compound, BTCA reacts with both the organophosphorus compound and cellulose, thus functioning as a binder between cotton cellulose and the organophosphorus compound and making the flame retarding system durable to laundering. The cotton fabric treated by the combination of the organophosphorus compound and BTCA demonstrated lower wrinkle resistance and less tensile strength loss than that treated by BTCA alone. The phosphorus retention on the cotton fabric after one home laundering cycle was approximately 70%. Copyright © 2003 John Wiley & Sons, Ltd.     

Effect of titanium dioxide on the flame‐retardant finishing of cotton fabric

In this study, titanium dioxide (TiO₂) or nano titanium dioxide (nano‐TiO₂) was used as a cocatalyst in the flame‐retardant (FR) formulation of N‐methylol dimethylphosphonopropionamide (Pyrovatex CP New, FR), melamine resin [Knittex CHN, crosslinking agent (CL)], and phosphoric acid (PA) for cotton fabrics to improve the treatment effectiveness and minimize the side effects of the treatment. For FR‐treated cotton fabrics, the flame extinguished right after removal of the ignition source with no flame spreading. However, after neutralization and/or home laundering, FR–CL‐treated specimens failed the flammability test, whereas the opposite results were obtained from FR–CL–PA‐treated specimens. A noticeable result was that the TiO₂/nano‐TiO₂ cocatalyst had a significant effect on decreasing the flame‐spread rate. Thermal analysis found that the FR‐treated specimens without wet posttreatment showed two endothermic peaks representing the phosphorylation of cellulose and acid‐catalyzed dehydration. In addition, the treated fabrics showed some new characteristic peaks in their chemical structures; these were interpreted as carbonyl bands, CH₂ rocking bands, and CH₃ asymmetric and CH₂ symmetric stretching. The surface morphology of the FR–CL–PA‐treated cotton specimens showed a roughened and wrinkled fabric surface with a high deposition of the finishing agent that had a lower breaking load and tearing strength, which resulted from the side effects of the CL used. However, the addition of a TiO₂ or nano‐TiO₂ cocatalyst could compensate for the reduction in the tensile strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Durable antimicrobial treatment of cotton fabrics using N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride and polycarboxylic acids

N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTCC), a water‐soluble chitosan quaternary ammonium derivative, was used as an antimicrobial agent for cotton fabrics. HTCC has a lower minimum inhibition concentration (MIC) against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli compared to that of chitosan; however, the imparted antimicrobial activity is lost on laundering. Thus crosslinking agents were utilized to obtain a durable antimicrobial treatment by immobilizing HTCC. Several crosslinkers such as dimethyloldihydroxyethylene urea (DMDHEU), butanetetracarboxylic acid (BTCA), and citric acid (CA) were used with HTCC to improve the laundering durability of HTCC treatment by covalent bond formation between the crosslinker, HTCC and cellulose. The polycarboxylic acid treatment was superior to the DMDHEU treatment in terms of prolonged antimicrobial activity of the treated cotton after successive laundering. Also, the cotton treated with HTCC and BTCA showed improved durable press properties without excessive deterioration in mechanical strength or whiteness when compared to the citric acid treatment. With the addition of only 0.1% HTCC to BTCA solutions, the treated fabrics showed durable antimicrobial activity up to 20 laundering cycles. The wrinkle recovery angle and strength retention of the treated fabrics were not adversely affected with the addition of HTCC. Therefore, BTCA can be used with HTCC in one bath to impart durability of antimicrobial activity along with durable press properties to cotton fabric. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1567–1572, 2003     

Fabric properties of butadienediepoxide-treated cottons as affected by liquid ammonia pretreatments

Effects of liquid ammonia and mercerizing-strength caustic as pretreatments upon textile properties of cotton sheeting modified with butadienediepoxide (BDO) catalyzed by 2% and 15% NaOH were compared. Tensile properties of the NaOH-mercerized control (CM) (celluloses I and II) greatly exceeded those of native (cellulose I) and ammonia-treated (NH₃) controls. NH₃(I) and NH₃(III) are those cottons having the cellulose I and mixed cellulose I and III lattices, respectively. Resistance to flex abrasion was doubled by pretreatments. Wrinkle recoveries of all controls were equivalent, but tensile recovery differed. BDO reaction enhanced wrinkle recovery of controls but produced the usual losses in tensile properties and resistance to flex abrasion associated with crosslinking reagents. BDO reaction nullified the initial tensile advantage held by CM cotton. Tear strengths of all BDO-treated cottons remained comparable. High dry and high wet recoveries were obtained only when 2% NaOH catalyzed the BDO reaction and were greatest for NH₃ cottons. BDO reaction reduced permanent set of all controls and increased tensile recovery primarily by enlarging the delayed recovery. Postmercerization with 23% NaOH adversely affected recovery behavior of all BDO-treated cottons. Nevertheless, wrinkle and tensile recoveries of postmercerized NH₃(I) and CM cottons were equivalent. Postmercerization partially restored fabric properties of BDO cottons with cellulose I lattice to those of their respective controls; no change was noted for corresponding products from CM cottons. Because of this, final properties of products from NH₃(I) cottons equaled and even exceeded those of comparable CM cottons.     

Synthesis of a quaternary ammonium derivative of chito‐oligosaccharide as antimicrobial agent for cellulosic fibers

A derivative of chito‐oligosaccharide (COS), N‐(2‐hydroxyl)propyl‐3‐trimethyl ammonium chito‐oligosaccharide chloride (HTACC), was synthesized using a reaction of glycidyltrimethylammonium chloride (GTMAC) and COS prepared by depolymerization of a fully deacetylated chitosan. COS and HTACC were applied to the cotton fabrics with a pad‐dry‐cure process using the reaction between the hydroxyl group of cellulose and terminal aldehyde group in COS and HTACC. Their minimum inhibition concentration (MIC) was evaluated, and the antimicrobial activity and durability to laundering of cotton fabrics treated with them were compared. The complete substitution of NH₂ groups in COS with GTMAC was obtained at a 4 : 1 mol ratio of GTMAC to NH₂ in 18 h at 80°C under the presence of acetic acid. MIC values of the 1.04 DS of HTACC and COS were 50 and 400 μg/mL, respectively. A cotton fabric treated with 0.2% of HTACC and 1.8% of COS exhibited 100% reduction of bacteria. At the 50th laundering cycle, 0.3% of HTACC and 2.4% of COS indicated 100% bacterial reduction. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 2009–2015, 2000     

Effect of in situ deposition of calcium carbonate in cotton fiber on its mechanical properties

In this study, in order to improve mechanical properties of cotton fabrics, nano-micro sized calcium carbonate (CaCO₃) was deposited in situ on cotton fabrics. The mechanical properties, surface morphology, crystalline index, infrared spectrum, thermal property, and wettability of the deposited fabrics were measured and discussed. The results showed that the breaking strength of cotton fabric increased by about 10% after in situ deposition of nano-micro calcium carbonate. After ultrasonic washing, the strength of cotton fabric deposited CaCO₃ was still increased by about 10%. The crystallinity of the cotton fabric deposited with calcium carbonate increased from 76% to 84%. The hydrogen bond between cellulose molecules and calcium carbonate was confirmed by infrared spectroscopy. The hydrophilicity and thermal properties of cotton fabric were not significantly influenced by calcium carbonate deposition. This provides a new idea for improving the mechanical properties of cotton fabric.     

Crosslinking cotton with poly(itaconic acid) and in situ polymerization of itaconic acid: Fabric mechanical strength retention

Polycarboxylic acids have been used as nonformaldehyde durable press finishing agents for cotton fabrics. Previously, we found that itaconic acid (IA) polymerized in situ on cotton fabric and also in an aqueous solution in the presence of a K₂S₂O₈/NaH₂PO₂ initiation system. Both poly(itaconic acid) (PIA) and the polymer formed by in situ polymerization of IA are able to crosslink cotton cellulose, thus imparting wrinkle resistance to cotton. In this research, we compared the performance of the cotton fabric crosslinked by PIA and that crosslinked by in situ polymerization of IA. The fabric treated with PIA and that treated with IA had similar wrinkle recovery angles. The cotton fabric treated with IA, however, lost more tensile strength than that treated with PIA due to cellulose degradation. We determined the magnitude of the fabric tensile strength loss attributed to crosslinking by separating the tensile strength loss due to cellulose degradation from the total tensile strength loss, and found that the tensile strength loss caused by crosslinking for the fabric treated with PIA was significantly higher than that for the fabric treated with IA. This can probably be attributed to more concentrated crosslinkages formed on the near surface of the PIA‐treated cotton fabric. PIA had poorer penetration into the amorphous cellulose region in fiber interior due to its much larger molecular size, thus increasing its concentration on the fabric's near surface. The data also suggest that more concentrated crosslinkages on the fabric surface reduced fabric abrasion resistance. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2023–2030, 2003     

Graft copolymerization of nitrogen‐ and phosphorus‐containing monomers onto cellulosics for flame‐retardant finishing of cotton textiles

Phosphoramide containing an active vinyl group (P‐III) was prepared. Its structure was confirmed by elemental analysis and Fourier transform infrared, nuclear magnetic resonance, and mass spectroscopy. P‐III was evaluated as a fire‐retardant finishing agent for cotton fabrics. It was applied to cotton fabrics using a graft process with an Fe²⁺/H₂O₂ redox system. The major factors affecting the reaction were studied. The finished cotton fabrics were examined for flammability, and the effect of washing on treated fabrics was also examined. The results showed that P‐III can be successfully used as a flame retardant for cotton fabrics. Durably flame‐retardant cotton fabrics were obtained at add‐on levels higher than 38%. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2573–2578, 2003     

Characteristics of cotton fabrics treated with epichlorohydrin and chitosan

Cotton fabrics treated with a crosslinking agent, epicholorohydrin, in the presence of chitosan (CEC) provide many possible reactive sites for reactive dyes and antimicrobial properties of the grafted chitosan to the cellulose structure. This process was applied by means of the conventional mercerizing process. The chitosan finishing and durable press finishing of the cotton fabrics occurred simultaneously in the mercerization bath. ECH is expected to react with hydroxyl groups in cellulose and chitosan or with amino groups in chitosan to form alcohol crosslinking by the Belfast process. The fixed chitosan content in the CEC was calculated by the nitrogen percentage of an Elemental Analyzer. The color strength (K/S) of the reactive dyes of the treated cotton fabrics did not significantly change with an increase of chitosan; however, the degree of swelling of the treated cotton fabrics decreased with an increase of chitosan and ECH. These performances were retained through 20 washing and tumble drying cycles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Recycling of waste cotton fabrics into regenerated cellulose films through three solvent systems: A comparison study

Large amounts of textile waste are generated every year and disposed of through landfill or incineration, leading to numerous environmental and social issues. In this work, the dissolution of three typical waste cotton fabrics (t-shirts, bed sheets and jeans) in NaOH/urea aqueous solution, H₂SO₄ aqueous solution, and LiCl/DMAc solution was investigated. Compared to different types of cotton fabrics, the effects of three solvents on the dissolution of fabrics were more obvious, leading to the significant changes in the structure and properties of regenerated cellulose films. Cotton fabrics (about 2%–5%) were rapidly dissolved (8 min) in H₂SO₄ and NaOH/urea solvents after acid pretreatment, while the dissolution in LiCl/DMAc solvent did not need any pretreatment, but a lower cellulose concentration (1%), higher dissolution temperature (80°C), and longer dissolution time (24 h) were required. The films produced from bed sheets in NaOH/urea solution exhibited the highest tensile strength, thermal stability, and water vapor barrier property. It was because of the stronger cellulose chain entanglement and hydrogen bonds induced by the higher cellulose concentration in NaOH/urea solution. Therefore, this work proves the feasibility to recycle waste cotton fabrics into biodegradable cellulose films, which can be potentially used in various food and agricultural applications.     

Chitosan phosphate induced better thermal characteristics to cotton fabric

Chitosan phosphate was prepared and applied at different concentrations with and without low formaldehyde N‐methylol finishing agent (resin) to cotton fabrics. Chitosan phosphate was characterized by FTIR, nitrogen content, and phosphorus content. The so‐treated fabrics were monitored for thermogravimetric analysis (maximum decomposition temperature and residue contents after decomposition), nitrogen content, phosphorus content, tensile strength, and elongation at break. Results indicate that extent of reaction of chitosan phosphate with the cotton fabric relies on concentration of the former; increasing the concentration of the resin has practically no effect on this reaction though the resin functions as a chemical bridge between the chitosan phosphate and the cotton fabric. On the other hand, the nitrogen of the resin and the phosphorus of chitosan undergo synergetic effect and enhance the thermal properties of the treated cotton. Strength properties display higher values in the presence than in the absence of chitosan phosphate when the latter was used along with the resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2021–2026, 2007     

Zur Reaktionsweise von Cellulose mit Alkalimetallen in flüssigem Ammoniak; reaktionskinetische Untersuchungen und eigenschaften von 2,3,6-Tri-O-lithiumcellulose

Structural data of ammonia swollen cellulose were obtained by kinetic investigations of the reaction of lithium, sodium and potassium with cotton fibers in liquid ammonia. The alkali metals reacted in a relatively rapid initial reaction with the accessible hydroxyl groups on the surface of structural units in the cellulose. The accessibility data found corresponded to those obtained by deuterium exchange in D₂O. While K/NH₃ did not react further with the ordered NH₃-cellulose a slow attack was found by Na/NH₃ with a constant rate. Faster was the reaction with Li/NH₃ (first order in cellulose). Thereby, characteristic differences were found between the used cellulose of differently ordered structures (cellulose I, II, III). This was traced back to the formation of different NH₃- cellulose-adducts. 2,3,6-Tri-O-lithiumcellulose was obtained from cotton cellulose without chain degradation. The lithium cellulosate was characterized by infrared spectroscopy, thermoanalytic investigations and by X-ray diffractions. Following measurements showed that cellulose reacted with Li/NH3 by a sheet lattice reaction.     

Cotton fabric graft copolymerization using microwave plasma. I. Universal attenuated total reflectance–FTIR study

The effect of microwave plasma on lightweight cotton fabric was investigated. N₂‐plasma, O₂‐plasma, and Ar‐plasma were obtained using a microwave generator at 2.45 GHz under vacuum. The universal attenuated total reflectance–Fourier transform infrared (UATR–FTIR) instrument was used to monitor the changes created after N₂‐, O₂‐, and Ar‐plasma treatments. The exposure of cotton fabrics to the plasma for 240 s with a microwave power of 500 W was sufficient to create active carbonyl groups, as shown by the presence of a peak around 1725 cm^?1 in the FTIR spectra of the treated cotton fabrics. Ar‐plasma was found to generate more active groups than N₂‐ and O₂‐plasmas. The active centers created within the cellulose chains were used to initiate copolymerization reactions with vinyl monomers to impart hydrophobic character to lightweight cotton fabric. The efficiency of the grafting process and the presence of grafted monomers on fabric surface were confirmed using UATR–FTIR. Testing of treated fabric revealed that excellent water repellency was obtained. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 145–154, 2004     

Ceric ion-induced redox polymerization of acrylonitrile on cellulose

The ceric ion-cellulose redox system has been studied for grafting acrylonitrile on cotton fibers. Grafting yields are very high as compared to the persulfate-thiosulfate redox system reported earlier. Traces of copper sulfate in the reaction mixture do not increase grafting yields, unlike the persulfate-thiosulfate system. The high polymerization rate on cotton fibers is shown to be due to the reducing action of cellulose and not to the large surface area of cotton fibers. The Ce⁺⁴ consumption during grafting is higher than during oxidation of cellulose, indicating formation of homopolymer during the grafting reaction. Studies on the consumption of Ce⁺⁴ by model compounds such as D-glucose and α-methyl-D -glucoside show that the hemiacetal group in D -glucose is responsible for a faster rate of Ce⁺⁴ consumption. Formation of a Ce⁺⁴-alcohol complex also contributes to the initial fast rate of Ce⁺⁴ consumption. Studies on the oxidation of cellulose by Ce⁺⁴ indicate that the initial oxidative attack occurs on carbon atom 2, with the formation of a >C?O group. On further oxidation, cleavage of the C₂-C₃ bond occurs as shown by the presence of glycol aldehyde determined chromatographically. Cellulose-polyacrylonitrile grafts have been isolated by an acetolysis treatment followed by extraction with dimethylformamide. Number-average molecular weights of the isolated fractions are approximately 50,000–55,000. A theoretical method to calculate the number-average molecular weights, based on the PAN and the COOH contents of the grafted cellulose, is described.     

The effects of weathering and atmospheric pollutants on cotton fabric and cotton fabric treated with selected flame retardants. I. Physical,chemical, and flammability properties

The effects of weathering and atmospheric pollutants on the physical, chemical, and flammability properties of cotton fabric treated with Pyrovatex 3805 and with THPOH-NH₃ flame retardant finishes and untreated controls were determined. The fabrics were exposed to SO₂, NO₂, and ozone singly and in combination for 50, 100, and 150 hr in a 2500-watt xenon arc Weather-Ometer using gas controls with and without light at a temperature of 35°C and a relative humidity of 90%. Excessive strength losses and large changes in D.P. for the untreated control occurred under all exposure conditions after 150 hr. Changes in the physical and chemical properties of the treated fabrics were moderated by the finishes, with Pyrovatex 3805 providing better protection to the cellulose than THPOH-NH₃. Elemental analysis and oxygen index measurements indicate that the Pyrovatex 3805 finish was severely degraded under these exposure conditions, with a resultant loss in flammability properties of the treated fabric after weathering. The THPOH-NH₃ finish was not appreciably affected by these exposure conditions and the treated fabric retained most of its flammability properties after weathering.