Latex Technology Research Articles

Characterization of the natural rubber vulcanizates obtained by different accelerators

Zinc diethyldithiocarbamate (ZDEC) is one of the most commonly used accelerators in natural rubber latex technology because of the properties of the corresponding vulcanizates. Many studies using this accelerator have shown the presence of carcinogenic nitrosamines and therefore its unsuitability for the production of some goods. The possibility of the substitution of the accelerator zinc diethyldithiocarbamate with zinc mercaptobenzothiazole, diphenylguanidine, or their combination, in the vulcanization of NR latex films was investigated. Four series of films were prepared by sulphur vulcanization, changing the accelerator and accelerator's concentration in a latex composition. The data covering the estimation of the network structure through crosslink density and distribution of different crosslink types, mechanical properties, and resistance to heat and ozone degradation are presented. The influence of the type and concentration of accelerators on these properties of vulcanized films was considered. The results show that the combination of accelerators zinc mercaptobenzothiazole/diphenyl-guanidine may be regarded as a proper substitute for zinc diethyldithiocarbamate as far as good film properties are desirable.

Polymeric surfactants in latex technology: polystyrene–poly(ethylene oxide) block copolymers as stabilizers in emulsion polymerization

AbstractPolystyrene–poly(ethylene oxide) PS–PEO di‐ and triblock copolymers have been used as stabilizers in the emulsion polymerization of styrene and styrene–butylacrylate for the preparation of “hairy latexes”. The polymerization kinetics and the efficiency of these polymeric surfactants were correlated with the molecular characteristics of the block copolymer. It was shown that the efficiency decreased with increasing molecular weight and PS content of the block copolymer.The PEO frige, with a thickness of 4–25 nm, on the latex particle surface could be characterized and it was shown by differential scanning calorimetry (DSC) that water is strucured in that PEO layer. Film formation with “hairy latexes” was also examined both by DSC and thermomechanical analysis. The properties and application possibilities, such as in controlled latex flocculation, have been reviewed.

Advances in emulsion polymerization and latex technology

Advances in emulsion polymerization and latex technology

Fatigue crack propagation and related failure in modified, andhydride-cured epoxy resins

The fatigue crack propagation (FCP) of neat and modified, anhydridecured epoxy resin (EP) was studied in tensile-tensile mode at ambient temperature. As modifiers, liquid carboxyl-terminated acrylonitrile-butadiene (CTBN) and silicon rubber (SI) dispersions were used. The latter modifier in a defined particle size distribution was produced by a special latex technology, whereas the former developed in situ in the EP by phase separation during curing. The dispersion-type morphologies of the EPs were characterized by using polished sections and viewing them in a scanning electron microscope (SEM). The resulting frequency distribution curves were compared with those analyzed from fatigue fracture surfaces. Probable failure mechanisms were also studied by SEM-fractography. Both modifiers improved the resistance to FCP by shifting the curves to higher stress intensity factor ranges (ΔK) in relation to the reference curve determined for the neat EP-matrix. The failure mechanisms, summarized also schematically, differed basically for the various modifiers. According to this, rubber-induced cavitation and shear yielding of the matrix seemed to be dominant for CTBN, which did not affect the principal crack plane. In contrast to this, crack bifurcation, branching and, hence, a forced deviation in the fatigue crack path induced by debonded SI-particles in the EP-matrix were concluded for the SI modifier. The common use of both modifiers yielded a positive synergistic effect due to the superposition of the above failure mechanisms.

Surface and interfacial FTIR spectroscopic studies of latexes. I. Surfactant–copolymer interactions

AbstractMolecular level interactions between surfactants and copolymers as well as transient effects during latex film formation play an important role in latex technology. Photoacoustic (PA) and attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy were utilized for the characterization of interactions between sodium dioctylsulfosuccinate and ethyl acrylate/methacrylic acid (SDOSS/EA/MAA) copolymer in latex films at both the film–air and film–substrate interfaces. It is shown that the splitting of the asymmetric SO stretching normal vibrations of the SO groups in the presence of Na+ counterions occurs only when weak COOH acid groups of latex are present. The absence of the COOH groups either by neutralization of latex or intentional synthesis eliminates the SO···HO associations that are the primary source of the symmetry changes resulting in the splitting of the SO symmetric mode at 1050 cm−1 to two bands at 1046 and 1056 cm−1.

Advances in emulsion polymerization and latex technology

Advances in emulsion polymerization and latex technology

A Novel Composite Polymer Latex Technology

The physical chemistry involved in the invention and development of a novel aqueous composite polymer latex technology at Dulux Australia is described. The polymerization process employed leads to a latex wherein each particle contains a blend of two or more copolymers. These particles are sterically stabilized by a new class of non-ionic reactive surfactant which results in excellent colloidal stability. A paint based on this technology has been commercialized in the coil coating industry. The particle size distribution of the latex used in this paint is studied before, during and after polymerization. The evidence obtained confirms that the desired composite polymer particles are formed by a suspension polymerization mechanism and that little or no polymer separation due to secondary nucleation (nucleation of polymer particles from the aqueous phase) takes place.

Advances in emulsion polymerization and latex technology

Advances in emulsion polymerization and latex technology

Advances in emulsion polymerization and latex technology 6–10 June 1983, Lehigh University, Bethlehem, PA.

Advances in emulsion polymerization and latex technology 6–10 June 1983, Lehigh University, Bethlehem, PA.

Special Topics in Latex Technology & Application

Special Topics in Latex Technology & Application

Electron Microscopy of Hevea Latex Gels

Abstract The use of preserved concentrated Hevea latex for the production of rubber articles has given birth, during the last decades, to a number of quite new technological methods in rubber manufacture. Starting from an aqueous rubber dispersion of low viscosity as a raw material, instead of the very tough viscoelastic solid rubber, may be advantageous in many respects. Latex technology, however, also presents its particular difficulties and drawbacks, one of which is concerned with the problem of the reinforcement of rubber. Reinforcing fillers like carbon black, which enhance the tear strength and abrasion resistance of masticated rubber, do not exhibit the same beneficial effect on the properties of rubber films cast from latex ; the same is true of all fillers if added in appreciable amounts, with the notable exception of resorcinol-formaldehyde resins formed in situ. Nevertheless, the strength of vulcanized cast films from latex is excellent in comparison with vulcanized sheets of masticated solid rubber. In order to get more insight into the factors which control the rheological and mechanical properties of wet as well as dried and vulcanized latex gels, an extensive study has been undertaken, part of which has been concerned with an elucidation of the structure of these gels by means of electron microscopy. The purpose of this paper is to describe the experimental methods for obtaining electron micrographs and to present some of the results. The rheological and mechanical properties will be discussed in forthcoming publications, one of which has appeared in print already.

Recent Progress in Latex Technology

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRecent Progress in Latex TechnologyE. A. MurphyCite this: Ind. Eng. Chem. 1952, 44, 4, 756–762Publication Date (Print):April 1, 1952Publication History Published online1 May 2002Published inissue 1 April 1952https://doi.org/10.1021/ie50508a027RIGHTS & PERMISSIONSArticle Views102Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts