Melt functionalization of LDPE with thio ester,amino ester,and hydroxy ester by thermolysis method—An FTIR study

Low density poly(ethylene) (LDPE) was melt functionalized with three different esters namely, thio ester, amino ester, and hydroxy ester under inert atmosphere at 160°C with different experimental conditions. During the functionalization reaction, crosslinking (C.L) and C?C formation are the simultaneous competitive reactions. FTIR‐RI analysis method was used to determine the % functionalization onto LDPE backbone and the order of functionalization reaction. Thermogravemetric analysis (TGA) and Differential scanning calorimetry (DSC) were used to assess the thermal properties of the functionalized LDPE. Suitable reaction scheme was proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Strain‐induced crystallization behavior of polychloroprene rubber

The crystallization behavior of polychloroprene rubber (CR) has been studied in this work. Differential scanning calorimetry (DSC) was applied to characterize the crystallization behavior. And X‐ray diffraction was applied to determine the impact of crosslinking on the crystallization of CR. Synchrotron X‐ray diffraction (SXRD) method was applied to study the dynamic crystalline behavior. On the basis of the experimental results, it is found that crosslinking will hamper the crystallization of CR while large strain can restore this course. And this is in accord with the Mooney‐Rivlin analysis result. Detailed discussion was offered circling around this phenomenon. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Swelling kinetic study and characterization of crosslinked hydrogels containing silver nanoparticles

The ammonium persulfate induced polymerization of acrylamide in the presence of silver nitrate (AgNO₃) and N,N′‐methylenebisacrylamide as a crosslinking agent were used to prepare crosslinked hydrogels containing silver ions. Subjecting this hydrogel to reduction with sodium hydroxide brought to focus the nanosilver hydrogel composites. Characterization of the latter, including proof of existence of silver nanoparticles in the hydrogel, was made. The number of silver nanoparticles embedded in the hydrogel matrix was higher at higher concentration of AgNO₃ used in the preparation of the nanosilver hydrogel composite. The characterization was performed by the use of ultraviolet–visible spectroscopy and transmission electron microscopy. The swellability of the hydrogel containing nanosilver particles was also studied, and the dependence of the swellability on the abundance of silver nanoparticles in the hydrogel composite was verified. It was further disclosed that the kinetic model matched the experimental data; meanwhile, the diffusion of water into the hydrogel was non‐Fickian type. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Cellulose as a renewable resource for the synthesis of wood consolidants

Crosslinkable cellulose ethers as allyl cellulose, allyl carboxymethyl cellulose, and allyl n‐hydroxypropyl cellulose were synthesized and characterized, and their use as consolidating agents for waterlogged wood was studied. For this kind of application, structural properties similar to those of wood's polysaccharide components are desired in the design stage of new consolidants. The choice to synthesize cellulose ethers was determined from the possibility of using cellulose as the starting material because of its large availability in nature, biocompatibility, and low cost. In addition, cellulose ethers are quite easy to obtain, and they can have different properties, depending on the nature and the amount of the functional groups introduced. For this purpose, a cellulose with a lower degree of polymerization was also used for the synthesis of related cellulose ethers. By means of Fourier transform infrared spectroscopy, the affinity of the cellulose derivatives for degraded lignin flours was detected. The preliminary results of this study show that these polysaccharide compounds may be proposed as wood consolidating agents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

Possibilities of polymer‐aided dyeing of cotton fabric with reactive dyes at neutral pH

Water‐soluble polymers have versatile application, viz., water‐soluble polyacrylates have been widely used in the reactive dyeing of cellulosic fibers and the related soaping as an important component of the leveling and washing agent. In this article, one such water‐soluble polymer, polyacrylic acid has been synthesized, characterized, and applied in conjunction with various types of reactive dyes, namely triazinyl, vinyl sulfone, high exhaustion, and bifunctional reactive dyes, along with crosslinking agents, namely glycerol 1,3‐dichlorohydrin and hexamethylene tetramine‐hydroquinone, respectively. One of the crosslinking agents (the former one) has been synthesized in the laboratory. Crosslinking agent is necessary to adhere the dye molecule onto the cellulose macromolecule. Different process sequences have been formulated and explored for dyeing purpose. All such dyeings were carried out at neutral pH. The dyed samples were assessed through color strength in terms of K/S values and their fastness properties were assessed by standard methods. All such dyeings were compared with conventional dyed samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

用于防水涂料的自交联丙烯酸弹性乳液

：以N-羟甲基丙烯酰胺（NMA）为自交联单体,SDS/OP-10为复合乳化剂,过硫酸铵（APS）为引发剂,采用半连续种子乳液聚合工艺和正交试验方法研究了不同用量的引发剂、乳化剂、交联单体和反应温度对弹性丙烯酸酯乳液性能的影响.结果表明：当APS、复合乳化剂和NMA用量分别为单体总量的0.7％、3％和1％,聚合温度为75 ℃时,可以制备出凝聚率低、转化率高、黏度和交联度适中的自交联丙烯酸弹性乳液;以其为基料与水泥复合制备的防水涂料涂膜吸水率较低,拉伸强度和断裂伸长率达到了国家标准以上.     

Surface modification of lignosulfonates for reinforcement of styrene–butadiene rubber compounds

In this study, surface modification of lignosulfonates (LSs) was investigated for potential reinforcement of styrene–butadiene rubber compounds. Lignins are naturally occurring amorphous, highly branched polymers consisting of aromatic and aliphatic segments with polar functional groups such as hydroxyl, methoxy, carbonyl, and carboxyl. The polarity and hydrophilic nature render lignin incompatible with nonpolar rubber materials. In this study, cyclohexylamine (CA) modification of LS was evaluated for enhancement of compatibility with rubber via proton transfer and hydrogen bonding interactions. X‐ray photoelectron spectroscopy data confirm attachment of CA onto the surface of LS. The cure and scorch times of rubber compounds were shortened, and the crosslink density enhanced with an increase of the amount of CA in modified LS. The tensile strength at break increased by almost 45%; the 100% modulus and elongation at break also showed significant improvements. The values of storage modulus and loss tangent increased by 13% and 18%, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40123.     

Beneficial role of “sol–gel” synthesized mesoscale silica networks on the performance of liquid silicone elastomer

This piece of contribution highlights the profound effect of unique mesoscale morphology of tailor made nanosilica assembly (SS‐Silica), synthesized by sol–gel route, on the mechanical and dynamic rheological properties of platinum catalyzed addition‐cured silicone elastomers. While commercial colloidal nanosilica (CS Silica) is used as the control nanofiller representing particulate morphology, the tailor‐made SS‐Silica having highly percolated network structure offers 10‐fold increase in storage modulus of the uncured reactive PDMS precursor nanocomposite with stable dynamic rheological behavior and more than 180% enhancement in tensile strength of resulting liquid silicone rubber (LSR) produced on curing, as compared to colloidal silica of commercial origin. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40125.     

Key factors influencing water diffusion in aromatic PA membrane: Hydrates,nanochannels and functional groups

Desalination by aromatic polyamide (PA) composite membranes is currently the most important technology of solving the global freshwater crisis. However, understanding the main factors influencing water diffusion in the desalination process remains a major hurdle in designing new membrane materials. Here, we investigate the key roles of the hydrates, the nanochannels in a PA membrane and the functional groups of the membrane on water diffusion by molecular dynamic simulations. Results show that the membrane can strongly hinder the diffusions of water molecules via both geometrical obstruction and water–membrane interaction when the radius of the water diffusion channel in the membrane is less than 8.75 Å. Conversely, the membrane has little influence on water diffusion. In a dilute NaCl solution, the effect of salt ions on the overall diffusion behavior of water can be neglected because only a small quantity of water molecules form hydrates. Almost all Na⁺ and Cl⁻, on the contrary, can form hydrates, which could explain why the PA membrane has a higher rejection level to salt ions rather than to water in seawater.