Mechanical and viscoelastic behavior of natural rubber and carboxylated styrene‐butadiene rubber latex blends

The morphology, mechanical and viscoelastic behavior of latex blends of unvulcanized natural rubber (NR) with carboxylated styrene‐butadiene rubber (XSBR) were investigated, with special reference to the effect of the blend ratio, temperature, and frequency. Mechanical properties like tensile strength, modulus, and elongation at break were also studied. As the XSBR content increased, the tensile strength increased up to a 50:50 NR/XSBR ratio and then decreased as a result of the self‐curing nature of XSBR. The dynamic mechanical properties of these latex blends were analyzed for loss tangent, storage modulus, and loss modulus. The entire blend yielded two glass‐transition temperatures, which corresponded to the transitions of individual components, indicating that the system was immiscible. To determine the change in modulus with time, a master curve of 50:50 NR/XSBR blends was plotted. Time–temperature superposition and Cole–Cole analysis were done to understand the phase behavior of the latex blends. The experimental and theoretical values of storage modulus of blends were compared using the Kerner and Halpin–Tsai models. With the help of optical micrographs, attempts were made to correlate the morphology and viscoelastic behavior of these blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2639–2648, 2003     

Dynamic rheology studies of carboxylated butadiene–styrene rubber/cellulose nanocrystals nanocomposites: Vulcanization process and network structures

A series of dynamic strain amplitude oscillatory shear experiments for vulcanization process of carboxylated butadiene‐styrene rubber/cellulose nanocrystals (XSBR/CNs) nanocomposites were performed to investigate the relationship between non‐linear viscoelasticity behaviors and crosslink network including chemical crosslink of XSBR and CNs‐related filler networks. The results showed that CNs accelerated the onset of gelation of XSBR and provided additional cross‐links to the XSBR/CNs composites. Because of the high aspect ratio, a homogeneous dispersion of rod‐like CNs was easy to form a rigid filler network within XSBR matrix. The XSBR chains adsorbed onto the surface of CNs through the hydrogen bonding interaction functioned as the cushioning materials during the oscillatory strain shear, resulting in an equilibrium condition of breakage and reforming CNs‐related networks at a relative higher strain magnitude. The kinetic XSBR chains during vulcanization and curing temperature were beneficial to accelerated aggregate forming of CNs, resulting in a reduced onset dropping stain magnitude. POLYM. COMPOS., 36:623–629, 2015. © 2014 Society of Plastics Engineers     

Phosphorylated cardanol prepolymer-grafted carboxylated styrene–butadiene rubber for better processing with enhancing silica filler dispersion

Cardanol is a byproduct of cashew industry of semiforest origin. It is cheap and available in humongous amount and acts as a multifunctional additive in rubber compounds. It can be oligomerized with orthophosphoric acid to make phosphorylated cardanol prepolymer (PCP). Hence, cardanol has been chemically grafted on to the backbone chain of carboxylated styrene–butadiene rubber (XSBR) by employing melt grafting technique in presence of peroxide initiator to include multifunctional properties. The PCP-grafted XSBR (PCP-g-XSBR) was characterized by using Fourier transform infrared spectroscopy and ¹H-NMR techniques and optimize the grafting conditions such as percent of grafting and grafting efficiency by using Taguchi methodology. PCP-g-XSBR was compounded with silica filler for a comparative study in terms of processing behavior with XSBR. The cure characteristics such as the cure rate and the optimum cure time of the unfilled PCP-g-XSBR compounds were determined by oscillating disc rheometer. The thermal analysis of PCP-g-XSBR vulcanizate exhibits slightly better thermal stability as well as plasticization effect. Morphological behaviors also display the less cracked and filled fracture surfaces with better filler dispersion in PCP-g-XSBR vulcanizate. The mechanical properties of the compounded PCP-g-XSBR vulcanizates also improve compare to XSBR vulcanizates. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47528.     

Thermal degradation and ageing behavior of microcomposites of natural rubber,carboxylated styrene butadiene rubber latices,and their blends

The effect of microfillers on the thermal stability of natural rubber (NR), carboxylated styrene butadiene rubber (XSBR) latices, and their 70/30 NR/XSBR blend were studied using thermogravimetric method. Microcomposites of XSBR and their blend were found to be thermally more stable than unfilled samples. The activation energy needed for the degradation of polymer chain was calculated from Coats‐Redfern plot. Activation energy needed for the thermal degradation of filled samples was higher than unfilled system. It indicated the improved thermal stability of the filled samples. The ageing resistance of the micro‐filled samples was evaluated from the mechanical properties of aged samples. The thermal ageing was carried out by keeping the samples in hot air oven for 7 days at 70°C. The mechanical properties such as tensile strength, modulus at 300% elongation, and strain at break were computed. As compared to unfilled samples, micron‐sized fillers reinforced systems exhibited higher ageing resistance. Finally, an investigation was made on the influence of ion‐beam irradiation on microcomposites of NR, XSBR latices, and their 70/30 blend systems using ²⁸Si⁸⁺ performed at 100 MeV. The surface changes of the samples after irradiation were analyzed using X‐ray photoelectron spectroscopy. The results of XPS measurements revealed that the host elements were redistributed without any change in binding energies of C_1s, O_1s, and Si_2p. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Rheological behavior of nanocomposites of natural rubber and carboxylated styrene butadiene rubber latices and their blends

Flow behavior of latices is industrially important for the manufacturing of various latex goods. Rheology of latices having fillers can assist in the understanding and quantification of the matrix–filler interaction. The impact of layered silicates such as sodium bentonite and sodium fluorohectorite on the rheological behavior of natural rubber, carboxylated styrene butadiene rubber latices, and their blends was analyzed with special reference to shear rate, temperature, and filler loading. The layered silicates‐reinforced latex samples were characterized by X‐ray diffraction technique to analyze the extent of intercalation and exfoliation. In the presence of layered silicates, latex systems exhibited enhancement in viscosity due to the network formation. Because of the breaking of networks at higher temperature, the viscosity of all systems decreased with increase in temperature. Layered silicates‐reinforced latex systems showed pseudoplastic flow behavior and possesses enhanced zero shear viscosity and yield stress. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2355–2362, 2006     

稀土氧化物／羧基丁苯橡胶复合材料的制备和性能研究

分别用4种稀土氧化物[氧化镧（La2O2）、氧化钐（Sm2O2）、氧化镝（Dy2O2）及氧化铕（Eu2O2）]和羧基丁苯胶乳（XSBR）机械共混,制备了稀土氧化物／XSBR复合材料。硫化曲线表明：4种稀土氧化物均可以不同程度加快XSBR的硫化速度。加入10份稀土氧化物,复合材料的硬度、拉伸强度、撕裂强度和模量均高于来填充XSBR。而拉断伸长率降低。其中La2O2／XSBR的拉伸强度最高,所得复合材料具有一定的荧光性能。     

Development of modified expanded graphite‐filled solution polymerized styrene butadiene rubber vulcanizates in the presence and absence of carbon black

Expanded graphite (EG) consists of a huge number of partially exfoliated graphite sheets with the thickness of most of the sheets in the nanometer range. This study analyses the effect of EG and modified EG (MEG) on the mechanical, thermal, and dynamic mechanical properties of solution styrene butadiene rubber (SSBR) with and without carbon black (CB). The surface of the EG was modified to enhance its dispersion in the SSBR matrix. In addition, oil‐extended carboxylated styrene butadiene rubber (XSBR) was used as a compatibilizer to disperse MEG in the base nonpolar SSBR matrix. XSBR/MEG nanocomposites have been prepared by solution mixing. The obtained nanocomposites were incorporated into the SSBR matrix in the presence of CB by melt blending. Morphological properties of the nanocomposites revealed intercalation of MEG sheets in the SSBR matrix. Nanocomposites containing MEG in the presence of CB show improvement in mechanical, thermal, and dynamic mechanical properties. POLYM. ENG. SCI., 54:33–41, 2014. © 2013 Society of Plastics Engineers     

Water‐induced mechanically adaptive behavior of carboxylated acrylonitrile‐butadiene rubber reinforced by bacterial cellulose whiskers

Water‐induced mechanically adaptive rubber nanocomposites were prepared by mixing bacterial cellulose whiskers (BCWs) suspension with carboxylated acerlonitrile‐butadiene rubber (XNBR) latex, followed by latex blending method. The introduction of BCWs into XNBR enhanced the tensile storage modulus (E') significantly, which originated from the formation of a rigid 3D filler network within matrix as well as the interfacial interaction between filler and matrix. The water uptake ratio of nanocomposite films increased with BCWs content, from 5.5% for neat XNBR to 54% for nanocomposite with 20 phr (parts per hundred rubber) BCWs. Upon submersed in water, the nanocomposite films showed dramatic decrease in E′, especially for which filled with high BCWs loadings. For example, E′ of nanocomposite with 20 phr BCWs was decreased by 98.04% after equilibrium swelling compared with only 52.02% for nanocomposite with 3 phr BCWs. The remarkable water‐triggered modulus changes are attributed to the disentanglement of BCWs network after swelling. The prepared XNBR–BCWs nanocomposites with mechanically adaptive properties could contribute to develop the new type of rubber‐based smart materials. POLYM. ENG. SCI., 59:58–65, 2019. © 2018 Society of Plastics Engineers     

Novel self‐crosslinking film from hydrogenated carboxylated nitrile rubber latex

A new type of self‐crosslinking latex film was prepared from hydrogenated carboxylated nitrile‐butadiene rubber (HXNBR) latex by diimide reduction. The properties of the HXNBR rubber, including film surface morphology, physical properties, thermal stability and ageing properties, were investigated. FTIR spectroscopy was used to confirm the HXNBR structure, from which the degree of hydrogenation can be obtained. The morphology of the film surface was monitored by atomic force microscopy, which confirmed that HXNBR latex can form a continuous film with good cohesive properties from self‐crosslinking latex particles. The self‐crosslinking provided the latex film with excellent tensile strength. The thermal stability was improved after hydrogenation, as indicated by thermogravimetric methods. The activation energy for degradation was determined by Coats‐Redfern plots. Hot air oven thermal ageing confirmed that the oxidation resistance increased as the degree of hydrogenation increased. All these results showed that HXNBR latex can form a self‐crosslinking film with better mechanical properties, and heat and oxidation resistance than those of XNBR latex film in a wide range of film applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39865.     

Gas transport through nano and micro composites of natural rubber (NR) and their blends with carboxylated styrene butadiene rubber (XSBR) latex membranes

The gas permeability coefficient of nano and micro composites of natural rubber, carboxylated styrene butadiene rubber and 70:30 natural rubber/carboxylated styrene butadiene rubber blend membranes has been investigated with special reference to type of filler, gases, filler loading and pressure. The layered silicates such as sodium bentonite and sodium fluorohectorite were the nanofillers used and the conventional micro fillers were clay and silica. Latex nanocomposites were characterized by X-ray diffraction technique. The dispersion of layered silicates in the polymer matrix was analysed using transmission electron microscopy. The fluorohectorite silicate showed excellent dispersion in natural rubber matrix. The effect of free volume on the gas barrier properties was investigated by positron annihilation lifetime spectroscopy. It was observed that due to the platelet like morphology and high aspect ratio of layered silicates, the gas barrier properties of nano filled latex membranes were very high. The crosslink density values and extent of reinforcement were estimated in order to correlate with the gas barrier properties. The oxygen/nitrogen selectivity of these membranes were investigated. The diffusion of gas molecules through the polymer was determined by time-lag method and diffusion selectivity of the membranes was computed.     

印刷电路板用阻焊油墨的研究

印刷电路板的制造过程当中,对其进行质量控制是非常重要的。为了有效提高印刷电路板的成品质量,通常情况下会在不需焊接的部位使用阻焊油墨进行涂布处理,目的是保护对应的部位。从阻焊油墨的相关工艺出发,主要介绍了喷墨打印技术加成法用阻焊油墨、柔性线路板用阻焊油墨以及水溶性碱显影感光阻焊油墨等,用以确定阻焊剂的具体应用。     

Effect of the carboxylic acid monomer type on the emulsifier‐free emulsion copolymerization of styrene and butadiene

Carboxylated styrene–butadiene rubber latexes were prepared through the emulsifier‐free emulsion copolymerization of styrene and butadiene with various carboxylic acid monomers. The effects of various carboxylic acid monomers on the particle formation process were investigated. The type of carboxylic acid monomer strongly affected the particle nucleation. The number of particles and thus the polymerization rate increased with the increasing hydrophobicity of the carboxylic acid monomers. There was a significant difference in the polymerization rate per particle. The results showed that particle nucleation and growth were dependent on the hydrophilic nature of the carboxylic acid monomers. The average particle diameter of the carboxylated styrene–butadiene rubber latexes in the dry state was obtained through some calculations using direct measurements of the average particle diameter in the monomer‐swollen state by a dynamic light scattering technique. Several parameters, such as the polymerization rate, number of latex particles per unit of volume of the aqueous phase, and polymerization rate per particle, were calculated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

硫化体系在丁腈手套制备中的应用

介绍了N-羟甲基丙烯酰胺（N-AM）硫化体系在丁腈手套制备中的应用。实验采用羧基丁腈胶乳（XNBRL）为原料,以N-AM为硫化剂、二丁基二硫代氨基甲酸锌（Bz）为促进剂、ZnO为硫化活性剂,经过预硫化、硫化、干燥等过程制得羧基丁腈胶膜。通过测试胶膜性能,研究了A（N-MA）、B（ZnO）、C（Bz）配比等因素对胶膜物理机械性能的影响,发现C（BZ）是影响胶膜物理性能的主要因素,其次是A（N-MA）和B（ZnO）。研究最终确定了最佳硫化体系配比A：B：C为3．5：2：1。     

Dual crosslinking of carboxylated nitrile butadiene rubber latex employing the thiol‐ene photoreaction

At present, the most common used crosslinking process for carboxylated nitrile butadiene rubber (XNBR) latex is an accelerated sulfur curing system with zinc oxide. To avoid allergenic reactions related to residual accelerator levels in dipped XNBR latex articles such as medical gloves, a dual curing process has been developed combining thermal and photochemical crosslinking reactions. The two‐step procedure involves the formation of covalent and ionic bonds to ensure good mechanical properties of the final products. The photochemical thiol‐ene reaction is used to generate covalent crosslinks between the remaining C?C double bonds of the butadiene units whereas the carboxylic moieties are conventionally cured with divalent metal oxides (ZnO) under elevated temperature (formation of ionic crosslinks). The photochemical curing step is carried out both in the latex phase using a falling film photoreactor (prevulcanization) as well as in the solid phase by UV irradiation of dried XNBR films (postvulcanization). The mechanical properties and crosslink densities of the cured XNBR films are determined and the influence of selected curing parameters is assessed. The results give evidence that a combined approach of thermal prevulcanization and photochemical postvulcanization makes the production of latex articles (e.g., gloves) with tailored properties and good skin compatibility feasible. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Developing the methodology of colour gamut analysis and print quality evaluation for textile ink‐jet printing: Delphi method

This research used the Delphi method to investigate current colour gamut analysis methods, which is a critical component of colour management systems (CMS). Thirteen ink‐jet printing experts were interviewed to understand how they manage colour and their process for analysing and comparing colour gamut. A significant result of this study was the development of a four‐stage process model for colour gamut analysis and print quality evaluation for textile ink‐jet printing. The optimal process model was verified and approved by experts. This study uncovered an industry initiative toward the improvement of CMS for more accurate colour matching, a need to stabilise variables in the manufacturing process, and a need to standardise related tests and evaluations. The study also revealed new CMS software and technologies developed for ink formulation and pre‐/post‐treatment methods to facilitate high quality production in textile ink‐jet printing.     

Protein influences on guayule and Hevea natural rubber sol and gel

Guayule (Parthenium argentatum) is under cultivation in the southwestern United States as an alternative source of natural rubber free from proteins that cause Type I latex allergies. However, since guayule lacks the protein‐polymer interactions present in Hevea latex, its physical and chemical properties may differ. The solvent‐soluble (Sol) and insoluble (Gel) fractions from guayule and Hevea natural rubbers were isolated through a solubilization/centrifugation deproteinization process. Protein could be reduced or removed by centrifugation, or concentrated in the gel fraction for both Hevea and guayule rubber. Separation of the sol fraction of Hevea rubber reduced the overall protein level, in some cases to below detection limits, without impacting rubber thermo‐oxidative stability. Notably, no detectable cross reactions took place between guayule protein antibodies and Hevea‐based materials, nor vice‐versa. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42051.     

Preparation and characterization of carboxylated styrene butadiene rubber (XSBR)/multiwall carbon nanotubes (MWCNTs) nanocomposites

This study deals with the preparation of carboxylated styrene butadiene rubber (XSBR)/multiwall carbon nanotubes (MWCNTs) nanocomposites prepared in the latex form by means of a ball mill. Two types of CNTs, i.e., non-functionalized and OH-functionalized (CNT?COH) were used. The rheological properties, FTIR spectrums, SEM micrographs and stress relaxation experiments were exploited to evaluate the resulting nanocomposites. For a given frequency, both the viscosity and storage modulus increased as the concentration of CNT was augmented with the greatest value for the nanocomposites loaded with CNT?COH. The viscosity of nanocomposites exhibited a shear thinning behavior throughout applied frequency and indicated a power law index of about n?=?0.22. Nanocomposite ATR analyses revealed the presence of physical interaction of H-bonding type between hydroxyl group of CNT?COH and carboxyl group of XSBR for XSBR?CCNTOH nanocomposites. A mechanism based on the chemistry of medium was proposed to explain the development of H-bonding. SEM micrographs confirmed the uniformity of carbon nanotubes dispersion in the resulting microstructure. A two-step innovative stress relaxation experiment was performed on the prepared nanocomposites through which the resulting microstructure of nanocomposites was further explored. The relaxation behavior of nanocomposites (both in first and second steps) were modeled and well predicted using Prony series and the parameters of generalized Maxwell equation for stress relaxation, $ \tau_{i} $ and $ g_{i} $ were computed, as well.     

UVA and UVC modification of photo polymeric surface and application for flexographic deposition of thin coatings

The object of this research was to perform, characterize, and apply the functional modification of flexographic photo polymeric printing plate surface by UVA and UVC post‐treatments. Photo polymeric printing plates have an important application in functional printing, where new printing inks/coatings and substrate formulations are used and the specific qualitative requirements must be met. The limitations of materials and processes often require expensive reformulations of the functional inks to achieve printability. Results of this research showed that the modification of the photo polymeric printing plate surface at the end of its production process can be used to precisely adjust the printing ink transfer to the printing substrate and thus eliminate the need for changing the ink/coating composition. By applying specific UV post‐treatment, one can create a flexographic coating deposition system of tailored properties adjustable to variable reproduction systems with high quality requirements. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43526.     

Rheological Characterization of Aqueous 3Y‐TZP Inks Optimized for Direct Thermal Ink‐Jet Printing of Ceramic Components

Aqueous 3Y‐TZP inks with solid contents of 22 and 27 vol% were used for fabricating three‐dimensional ceramic components by the direct ink‐jet printing process (DIP). The DIP fabrication was realized using a thermal ink‐jet (TIJ) printing system. Despite the different physical properties of the inks, both inks were successfully ejected and deposited. To define the optimum window of the ink properties required for a stable printing operation, both ceramic inks as well as a typical TIJ ink were characterized in terms of particle size distribution, zeta potential, viscosity, surface tension, and the inverse Ohnesorge number (Oh^?1). Moreover, single drops of all inks were deposited and analyzed by scanning electron microscopy (SEM) to examine the form and integrity of the ejected drops. Demonstration objects (a base with curved channels and a sample molar tooth) were DIP fabricated using both of the ceramic inks. These objects show the potentials of the DIP process for ceramics manufacturing particularly by using TIJ printing systems.     

Functionalization of styrene–butadiene rubber with meta‐pentadecenyl phenol for better processing: A multifunctional additive and renewable resource

Meta‐pentadecenyl phenol, a nonisoprenoid phenolic lipid, is a renewable agricultural resource and also a byproduct of the cashew industry; it is popularly known as cardanol. This study throws light on the grafting of cardanol, which has been established as a multifunctional additive for natural rubber, onto the main‐chain backbone of styrene–butadiene rubber (SBR), a synthetic polymer used to imbibe the multifunctional properties of the former, such as those of a plasticizer, curing promoter, process aid, and antioxidant, into the latter. The grafting was carried out in the solution stage on a trial basis with a peroxide catalyst, and all of the grafting parameters were optimized with a Taguchi methodology. The grafting of cardanol onto the SBR backbone was successfully confirmed by UV–visible spectroscopy, Fourier transform infrared spectroscopy, and NMR analysis. Thermal analysis of the cardanol‐grafted styrene–butadiene rubber (C‐g‐SBR) revealed a higher thermal stability and better plasticizing effect than that those found in the virgin SBR. The rheological properties of the grafted rubber indicated the improvement of the pseudo‐plastic (shear‐thinning) nature compared to that in gum SBR. The unfilled C‐g‐SBR vulcanizates exhibited physicomechanical properties comparable to 5‐phr processing‐oil‐containing SBR [oil‐plasticized styrene–butadiene rubber (OPSBR)] vulcanizates. The carbon‐black‐filled C‐g‐SBR vulcanizates exhibited improved plasticization, a faster curing rate, easy processability, and better physicomechanical properties compared to the 5‐phr OPSBR vulcanizates. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45150.