Crosslinking of cotton cellulose in the presence of serine and glycine. I. Physical properties and reaction kinetics

Serine and glycine were used to combine with dimethyloldihydroxyethyleneurea (DMDHEU) as crosslinking agents to study the physical properties of the crosslinked fabrics and the reaction kinetics, and find that the bound nitrogen is in the series of DMDHEU ? DMDHEU‐serine > DMDHEU‐glycine at the same resin concentration. The results also show that the wet crease recovery angle (WCRA) value of the treated fabrics for the three crosslinking agent systems is in the series of DMDHEU‐serine > DMDHEU‐glycine > DMDHEU alone at a given dry crease recovery angle (DCRA). The DCRA values of the treated fabrics for DMDHEU alone are higher than those for DMDHEU‐α‐amino acids for a given value of tensile strength retention (TSR). WCRA values for the various treated fabrics is in the rank of DMDHEU‐serine > DMDHEU alone > DMDHEU‐glycine at the same TSR. Rate constants for the various crosslinking agents are in the series of DMDHEU‐glycine > DMDHEU‐serine > DMDHEU alone at the given heated temperatures. Energies needed to crosslink and the values of enthalpies and entropies of activation are all DMDHEU‐glycine > DMDHEU‐serine > DMDHEU alone. Infrared ray (IR) spectra strongly suggest the reaction between DMDHEU and serine and the reaction between the hydroxyl group (cellulose) and serine can occur in the pad‐dry‐cure process, but only a little for the latter. The reaction between the functional groups of serine and the aluminum ion to form a complex also confirm with IR spectrum. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 595–603, 2005     

Crosslinking of cotton cellulose in the presence of serine and glycine. II. Pore structures and agent distribution

Serine and glycine are selected as coreactants to combine with dimethylol‐dihydroxyethyleneurea (DMDHEU). We found that the pore structures of DMDHEU‐crosslinked cottons are changed. DMDHEU alone has lower values of equilibrium absorption, structural diffusion resistance constant, and rate constant, but higher value of activation energy than do DMDHEU–serine and DMDHEU–glycine. On the other hand, DMDHEU–serine has higher values of structural diffusion resistance constant and lower values of equilibrium absorption and rate constant than does DMDHEU–glycine; however, the hydroxyl group contained in serine has the higher affinity toward direct dye resulting in the decrease in the value of activation energy. The expansion patterns of cross section show that the degree of the expansion of the DMDHEU‐crosslinked fiber is lower than that of the DMDHEU–serine‐ and DMDHEU–glycine‐crosslinked fibers. The distribution of crosslinking agents on the crosslinked fabrics reveals the slightly higher surface distribution of DMDHEU–serine and DMDHEU–glycine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1578–1584, 2006     

Crosslinking of cotton cellulose in presence of alkyl di‐allyl ammonium salts. III. Study on pore structure of treated fabrics from dyeing kinetics

Two kinds of alkyl di‐allyl ammonium salts (alkyl groups = methyl and propyl) as crosslinking agents are combined with dimethyloldihydroxyethyleneurea (DMDHEU) to study rate constants, structural diffusion resistance constants, and other parameters of dyeing. The dye absorptions for the various crosslinking agents are ranked DMDHEU–propyl di‐allyl ammonium salt > DMDHEU–methyl di‐allyl ammonium salt > DMDHEU, and the equilibrium absorption values are ranked DMDHEU–propyl di‐allyl ammonium salt > DMDHEU–methyl di‐allyl ammonium salt > DMDHEU. The dyeing rate constants and structural diffusion resistance constants of the finished fabrics are in the order DMDHEU–methyl di‐allyl ammonium salt > DMDHEU–propyl di‐allyl ammonium salt > DMDHEU; however, the activation energies are ranked inversely. The treated fabrics for DMDHEU–alkyl di‐allyl ammonium salts have a larger pore structure than those for DMDHEU. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 862–866, 2005     

Structure and mechanical properties of novel composites based on glycidyl azide polymer and propargyl‐terminated polybutadiene as potential binder of solid propellant

Instead of the traditional isocyanate curing system as the binder of solid propellant, a triazole curing system has been developed by the reaction of azide group and alkynyl group due to a predominant advantage of avoiding to the interference of humidity. In this work, the propargyl‐terminated polybutadiene (PTPB) was blended with glycidyl azide polymers (GAPs) to produce new composites under the catalysis of cuprous chloride at ambient temperature. The triazole‐crosslinked network structure was regulated by changing the molar ratio of azide group in GAP versus alkynyl group in PTPB, and hence various crosslinked densities together with the composition changes of GAP versus PTPB cooperatively determined the mechanical properties of the resultant composites. Furthermore, the formed triazole‐crosslinked network derived from the azide group in GAP and alkynyl group in PTPB resulted in the slight increase of glass transition temperatures and a‐transition temperatures, and improved the miscibility between GAP and PTPB. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40007.     

Structure and properties of composites of polyethylene or maleated polyethylene and cellulose or cellulose esters

Composites of linear low‐density poly(ethylene‐co‐butene) (PE) or maleated linear low‐density poly (ethylene‐co‐butene) (M‐PE) and cellulose (CEL), cellulose acetate (CA), cellulose acetate propionate (CAP), or cellulose acetate butyrate (CAB) were prepared in an internal laboratory mixer with 20 wt % polysaccharide. The structure and properties of the composites were studied with tensile testing, dynamic mechanical thermal analysis, differential scanning calorimetry, extraction with a selective solvent, Raman spectroscopy, and X‐ray diffraction. Composites prepared with M‐PE presented yield stress and elongation values higher than those of composites prepared with PE, showing the compatibilizer effect of maleic anhydride. Dynamic mechanical thermal analysis performed for M‐PE–CEL, M‐PE–CA, M‐PE–CAP, and M‐PE–CAB composites showed one glass‐transition temperature (T_g) close to that observed for pure M‐PE, and for M‐PE–CAP, another T_g lower than that measured for the polysaccharide was observed, indicating partial mutual solubility. These findings were confirmed by the extraction of one phase with a selective solvent, gravimetry, and Raman spectroscopy. X‐ray diffraction showed that the addition of CEL, CA, CAP, or CAB had no influence on the lattice constants of PE or M‐PE, but the introduction of the reinforcing material increased the amorphous region. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:402–411, 2007     

Influence of epichlorohydrin content on structure and properties of high‐ortho phenolic epoxy fibers

The high‐ortho phenolic epoxy fibers (HPEFs) were prepared by the crosslinking of heat‐meltable spun filaments derived from melt‐spinning of the novolac epoxy resins copolymerized among phenol, formaldehyde, and epichlorohydrin (ECH) in the presence of zinc acetate and sulfuric acid catalyst, and cured in a combined solution of formaldehyde and hydrochloric acid. The resulting fibers were heat‐treated in N₂ at elevated temperature. Infrared (IR) spectrometer, thermogravimetric analysis (TGA), scanning electron microscope (SEM), and electrical tensile strength apparatus were employed to characterize the change of functional groups, thermal performance, microstructure of fibers, and mechanical properties. The results show that the addition of ECH in the precursor resin can increase the content of long alkyl ether linkage, and gain the peak of thermal stability and mechanical strength. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43375.     

Crosslinking reactions of oxidized cellulose fiber. I. Reactions between dialdehyde cellulose and multifunctional amines on lyocell fabric

Fibrillation‐controlled lyocell fibers were developed by crosslinking reactions between dialdehyde cellulose (DAC) and multifunctional amines. DAC lyocell fibers were manufactured by partial oxidation with sodium metaperiodate and were successfully crosslinked with two multifunctional amines by Schiff‐base formation. The amorphous regions and the char formations, which were characterized by differential scanning calorimetry and thermogravimetric analysis, increased with the degree of oxidation. After the crosslinking reactions, an increase in the amorphous regions also appeared, whereas the thermal stability was somewhat improved by the chain crosslinking. These results were in good agreement with viscosity‐average degree of polymerization values in that they diminished with oxidation level and increased with the crosslinking reactions. The water retention value and moisture regain value decreased with the oxidation and crosslinking levels, which implied that the swellability of fibers and the water absorbency in characteristic sites decreased with them. The increase in the dry crease recovery angle also confirmed the presence of hemiacetal crosslinks in the DAC and amine crosslinks between the DAC and the amines. The fibrillation grade of the crosslinked fibers diminished with oxidation level and the amine concentration. In particular, the fibrillation properties of the crosslinked fibers with 4‐hydroxy‐2,4,6‐triaminopyrimidine sulfate salt were more easily controlled than those of the crosslinked fibers with 2,4,6‐triamino‐1,3,5‐triazine. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of microporous cellulose membranes from novel cellulose/aqueous sodium hydroxide solutions

Microporous cellulose membranes were prepared from novel cellulose/aqueous sodium hydroxide solutions by coagulation with aqueous H₂SO₄ solutions. The free and glass‐contacting surface morphology of the microporous cellulose membranes showed an asymmetric porous structure. The morphological structure, tensile properties, and permeability of the microporous cellulose membranes could be controlled by changes in the coagulation conditions such as the coagulant concentration and the coagulation time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 920–926, 2006     

Crosslinking structures and dyeing kinetics of cotton cellulose treated with a steeped process

A steeped procedure was introduced to the durable press finishing process in this study to study some physical properties, the crosslinking structure, and the pore structure. The results showed that the values of the dry and wet crease recovery angles of fabrics treated with the steep–pad–dry–cure process were higher than those of fabrics treated with the pad–dry–cure process, and those phenomena increased with higher steeped temperatures and longer times. The lengths of the crosslinks for the steep–pad–dry–cure process were higher than those for the pad–dry–cure process at a given number of crosslinks per anhydroglucose unit. The fabrics treated with the steep–pad–dry–cure process had higher values of the dye absorption, rate constant, and structural diffusion resistance constant than those treated with the pad–dry–cure process at the same dyeing temperature; however, they had lower values of the equilibrium absorption and activation energy than those treated with the pad–dry–cure process. The results of thin‐layer chromatography, H‐NMR, ¹³C‐NMR, and IR analyses suggested that self‐condensation between the crosslinking agents occurred during the steeped procedure. Additionally, the steep–pad–dry–cure‐treated fabric had more inner agent distribution than the pad–dry–cure‐treated fabric. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2555–2562, 2005     

含物理交联高吸油树脂的合成和吸油性能

提出在单一化学交联吸油树脂中引入物理交联的设想，并采用悬浮聚合法全盛了含部分物理交联和单一化学交联的高吸油聚丙烯酸酯。研究了聚合温度、反应时间以及引发剂、分散剂用量和交联剂形式及用量对树脂形态、凝胶分率和吸三氯乙烯、苯等的影响。结果表明物理交联和化学交联方式对树脂的吸油性能影响较大。     

Physical properties of crosslinked cellulose catalyzed with nano titanium dioxide

Four different carboxylic acids, 1,2,3,4‐butane tetracarboxylic acid (BTCA), maleic acid (MA), succinic acid (SUA), and citric acid (CA), were used as crosslinking agents to treat cotton fabrics in the presence of nanometer titanium dioxide (TiO₂) as a catalyst under UV irradiation. The dry crease recovery angle (DCRA) and wet crease recovery angle (WCRA) values of the treated fabrics were ranked BTCA > MA > CA > SUA and the tensile strength retention (TSR) values were ranked BTCA < MA < CA < SUA at a given resin concentration, catalyst concentration, and irradiation time period. The physical properties of the treated fabrics for nanometer silver/nanometer titanium dioxide (Ag/TiO₂) catalyst showed the same tendency. At a given DCRA, the WCRA values were ranked in the order BTCA ≒ MA > CA ≒ SUA; and at a given value of the TSR, the WCRA and DCRA values were both ranked in the order BTCA > MA > CA > SUA. The softness values of the carboxylic acid treated fabrics in the presence of nanometer TiO₂ catalyst were all better than that of the untreated fabric. Surface deposition of the treated fabrics for BTCA, which contains one vinyl double bond and four carboxylic acid groups, was higher than that for CA, which contains no vinyl double bond. IR spectra and electron spectroscopy for chemical analysis survey spectra showed the ester bond crosslink between the cellulose molecule and the various acids used in this study. The values of DCRA, WCRA, and add‐on of the CA crosslinked fabrics for the mixed catalysts were in the order ZrO₂/TiO₂ < SiO₂/TiO₂ < Ag/TiO₂. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2450–2456, 2005     

Structure modification and crosslinking of methacrylated polylactide oligomers

The effect of molecular architecture on the properties of crosslinked polylactides was studied. D,L ‐Lactide‐based telechelic oligomers with different numbers of arms were functionalized with methacrylic anhydride. Functionalized oligomers were crosslinked with thermal initiation at 90°C, and the mechanical and thermal properties, as well as the gel content, were evaluated. The crosslinking density increased with the number of arms in the oligomers, and the compressive yield strength was built up at the same time. The best mechanical properties (compressive yield strength = 120 MPa, modulus = 2800 MPa, and strain = 5.0%) were obtained with cured polymers prepared with a 100 : 8 ratio of lactide to pentaerythritol. When dimethacrylated butanediol was used as a reactive monomer in curing, polymers with high crosslinking density and mechanical strength were obtained at 37, 60, and 90°C. The use of the reactive monomer also enabled high conversions with photoinitiated crosslinking. Finally, hydrolytic degradation and strength retention were demonstrated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3616–3624, 2002     

Melt extrusion of polyethylene nanocomposites reinforced with nanofibrillated cellulose from cotton and wood sources

Replacing petroleum‐based materials with biodegradable materials that offer low environmental impact and safety risk is of increasing importance in sustainable materials processing. The objective of this study was to produce uniform nanofibrillated cotton from recycled waste cotton T‐shirts using microgrinding techniques and compare its performance as reinforcing agent in thermoplastic polymers constructs with wood‐originated materials. The effect of the microgrinding process on morphology, crystallinity, and thermal stability of materials was evaluated by transmission electron microscopy (TEM), scanning electron microscope (SEM), X‐ray diffraction (XRD), and thermogravimetry analysis (TGA). Nanofibrillated cotton resulted in higher crystallinity and thermal stability than fibrillated bleached and unbleached softwood. All the materials were extruded with low‐density polyethylene to fabricate nanocomposite films. Nanofibrillated cotton nanocomposites had a higher optical transparency than did the wood‐based composites. The mechanical properties of the nanofibrillated cotton nanocomposites were largely improved and showed 62.5% increase in strength over the wood‐based nanofibrillated containing composites, in agreement with the higher crystallinity of the nanosized cotton‐derived filler material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41857.     

Mechanical behavior,microstructure and thermooxidation properties of sequentially crosslinked ultrahigh molecular weight polyethylenes

The aim of this study was to explore the impact of the sequential irradiation and annealing process on the microstructure, thermooxidation behavior and mechanical properties of GUR 1050 ultrahigh molecular weight polyethylene (UHMWPE) with respect to the postirradiation annealed material. For this purpose, the effects of a variety of irradiation and annealing conditions on microstructure and mechanical properties were investigated. Differential scanning calorimetry was performed to characterize melting temperature, crystalline content and crystal thickness, whereas transmission electron microscopy provided additional insights into crystal morphology. Thermogravimetric experiments in air served to assess thermooxidation resistance and changes associated to radiation‐induced crosslinking. Fatigue properties were studied from three different approaches, namely short‐term cyclic stress–strain tests, long‐term fatigue experiments and crack propagation behavior. Likewise, three experimental techniques (uniaxial tensile test, impact experiments, and load to fracture of compact tension specimens) allowed evaluation of the fracture resistance. The present findings confirm sequentially crosslinked UHMWPE exhibited improved thermooxidation resistance and thermal stability compared to post‐irradiation annealed UHMWPE. Also, the mechanical behavior, including the fatigue and fracture resistance, of these materials was generally comparable regardless of the annealing strategy. Therefore, the sequential irradiation and annealing process might provide higher oxidation resistance, but not a significant improvement in mechanical properties compared to the single radiation dose and subsequent annealing procedure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Alkaline treatment of cotton in different reagent mixtures with reduced water content. I. Influence of alkali type and additives

The purpose of this study was to examine the influence of some swelling agents with reduced water content on final properties of cotton fabrics. A single‐step swelling of cotton in the reagent was used. There were selected properties generally used to characterize mercerized cotton that are technologically important, such as water retention, shrinkage, stiffness, crease recovery angle, and hand. Water retention method and dyeing with CI Direct Red 81 have been used to compare the degree of swelling for different samples. Correlations have been established between structural changes induced by the swelling agents and final properties of cotton fabric. The mixtures of an alkali solution and an additive produced similar or better end‐use properties as compared with classical sodium hydroxide or ammonia treatments, combining the action of a diluted alkali solution (3.13 mol/L NaOH or KOH) and a nonalkali reagent. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2848–2855, 2006     

Effect of the crosslinking density and programming temperature on the shape fixity and shape recovery in epoxy–anhydride shape‐memory polymers

In addition to the fabrication of thermoset epoxy–anhydride shape‐memory polymers (SMPs), a systematic experimental investigation was conducted to characterize the crosslinking density, micromorphology, thermal properties, mechanical properties, and shape‐memory effects in the epoxy SMP system, with a focus on the influence of the crosslinking density and programming temperature on the shape‐fixity and shape‐recovery behaviors of the polymers. On the basis of the crosslinking density information determined by NMR technology, we concluded that the effect of the crosslinking density on the shape‐fixity behaviors was dependent on the programming temperature. The advantage of a nice combination of crosslinking density and programming temperature provided an effective approach to tailor the actual shape recovery within a wide range. The increasing crosslinking density significantly improved the shape‐recovery ratio, which could be further improved through a decrease in the programming, whereas the crosslinking density was more fundamental. This exploration should play an important role in the fabrication and applications of SMP materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40559.     

Physical properties and reaction kinetics of cotton cellulose crosslinked with dimethyloldihydroxyethyleneurea–maleic acid

Two dicarboxylic acids were used to join with dimethyloldihydroxyethyleneurea (DMDHEU) as crosslinking agents to treated cotton fabrics. These results reveal that the dry crease recovery angle values of the treated fabrics for DMDHEU–maleic acid are higher than those for DMDHEU–tartaric acid at a given wet crease recovery angle and tensile strength retention. The IR spectra show that the reaction between the –OH of DMDHEU and cellulose and the vinyl groups of maleic acids occurred. The cross section of the DMDHEU–maleic acid and DMDHEU–tartaric acid treated fibers and the energies of activation and other data of reaction kinetics for DMDHEU–maleic acid and DMDHEU–tartaric acid strongly suggest that the reaction of vinyl groups of maleic acid with cellulose molecules can take place during the pad/dry‐cure process. Additionally, the surface distribution of crosslinking agent on the finished fabrics for DMDHEU–maleic acid is slightly lower than that for DMDHEU–tartaric acid. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3886–3893, 2004     

New crosslinked polyurethane elastomers with various physical properties from natural rubber derivatives

New hydroxytelechelic cis‐1,4‐oligoisoprenes exhibiting variable values and distributions of the hydroxyl functionality were successfully prepared. The synthesis reactions involved chemical modifications of carbonyl telechelic cis‐1,4‐polyisoprene, which was obtained by controlled degradation of synthetic or natural rubber. These new oligomers were reacted with toluene diisocyanate to elaborate crosslinked polyurethane elastomers. The thermomechanical properties of the prepared polyurethanes were investigated. The results show a strong relationship between the chemical structures and properties. This work mainly shows the potentiality of making new crosslinking polyurethane materials with controlled and various properties from natural rubber, a renewable resource. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Structure and mechanical properties of crosslinked glycidyl azide polymers via click chemistry as potential binder of solid propellant

Depending upon the advantages of high efficiency, insensitivity to humidity and so on, the reaction of azide groups in glycidyl azide polymers (GAP) with alkynyl compounds has been used as a substitute of the urethane curing strategy to develop GAP‐based binder for solid propellant. In this work, an alkynyl compound of dimethyl 2,2‐di(prop‐2‐ynyl)malonate (DDPM) reacted with GAP to produce new crosslinked materials under the catalysis of Cu(I)Cl at ambient temperature, and showed great potential as a binder in composite propellant. As the feeding molar ratio of DDPM vs. GAP increased from 1 : 1 to 5 : 1, the crosslinking densities of as‐prepared materials gradually increased, together with simultaneous enhancement of Young's modulus and tensile strength. The breaking elongation showed the maximum value of ca. 82% when the feeding molar ratio of DDPM vs. GAP was 3 : 1. In addition, with an increase of the crosslinking densities, the glass transition temperatures of as‐prepared materials significantly increased from ?43.9°C to ?5.1°C while the mechanical loss peaks also gradually broadened and shifted up to high temperature, and even presented two peaks at the feeding molar ratio of DDPM vs. GAP higher than 4 : 1. It indicated that the formation of triazole‐based network resulted in structural heterogeneity in the as‐prepared materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40636.     

Carboxymethyl cellulose reinforced poly(vinyl alcohol) with trimethylol melamine as a chemical crosslinker

In this investigation, carboxymethyl cellulose (CMC)‐reinforced poly(vinyl alcohol) (PVA) were prepared with trimethylol melamine as a chemical crosslinker. The structure and property of hydrogels were measured by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), texture analysis, and rheometry. The FTIR spectra demonstrated that the etherification reaction successfully occurred in the PVA–CMC hydrogels, and the SEM figures exhibited the homogeneous porous structure of the CMC–PVA hydrogels. The compression strength of the PVA–CMC hydrogels was 15 times higher than that of the PVA hydrogels. Moreover, the PVA–CMC hydrogels exhibited a higher storage modulus than that of the PVA hydrogels; this illustrated better elasticity for the PVA–CMC hydrogels. As a result, CMC‐modified PVA hydrogels with high mechanical behavior will broaden the potential applications of hydrogels, such as in wound dressings, facial masks, and skin‐protection layers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44590.