Properties Of Latex Research Articles

Facile fabrication and modification of polyacrylate/silica nanocomposite latexes prepared by silica sol and silane coupling agent

Polyacrylate/silica nanocomposite latexes were prepared by silica sol and facilely modified with a silane coupling agent γ-methacryloxypropyltrimethoxysilane (KH-570) aimed at reinforcing the interaction between silica nanoparticles and latex particles in a convenient way. The effects of silica sol and KH-570 amounts on the performance of latexes and films are discussed. Particle size and morphology tests demonstrated that the silica nanoparticles could form hydrogen bond interactions between latex particles, and thus influence the rheological properties of latexes. Tensile measurements and SEM photographs showed the reinforcing and toughening roles of silica nanoparticles. SEM images also indicated that the addition of silica sol increased the roughness of films, which resulted in the increase of hydrophilic silanol groups on the film surface and the decrease of water resistance of latex films. The latex films retained good adhesion force, flexibility, and impact resistance even when the silica sol content was as much as 25%. TGA data revealed that the incorporation of silica sol enhanced the thermal stability of the films. After introducing KH-570, the particle size increased with the increase of the amount of KH-570. Moreover, the addition of KH-570 improved the water resistance and maintained other properties of the latex films appropriately.

Industrial Production of Poly Vinyl Acetate Dispersions: Relationship Between Latex Properties and Polymerization Start-Up Temperature

An industrial polymerization process for the production of polyvinyl alcohol stabilized polyvinylacetate dispersions has been examined to investigate the influence of the start-up temperature on production process and latex characteristics. The product investigated is a high solids, high viscosity latex, obtained by a semi-batch emulsion polymerization process, initiated with persulfate. The main finding shows that small variations of the start-up temperature affect the reaction kinetics in the first stage of polymerization and have a direct influence on physicochemical and rheological properties of the finished products.

Synthesis and properties of the cationic fluorocarbon emulsifier-free latex in a new micellar system

Cationic fluorocarbon emulsifier-free latex (CFEL) based on hexafluorobutyl methacrylate (FA), styrene, butyl acrylate, and methacrylatoethyl trimethyl ammonium chloride is successfully prepared in a new micellar system in which the fluorinated surface active monomer (FSM) based on isophorone diisocyanate, dodecafluoroheptanol, and allyl polyethylene glycol is used. The chemical structure of FSM is characterized by Fourier transform infrared spectroscopy, 1H-NMR, and its surface-active properties have been investigated by surface tension determinator. Besides, effect of FSM, FA, and also the curing temperature on the latex and film properties has been investigated by the coagulation ratio (Wc), precipitation ratio (Wp), Nano-ZS particle sizer, contact angle, and water absorption ratio, respectively. The results show that the FSM is successfully prepared. The CMC of FSM is 2.37 g L−1 and the γCMC is 26.31mN m−1 accordingly. The more FSM content makes more stable emulsion and have only little adverse effect on its film properties. When the FSM content increases from 1.05 to 13.11 %, the Wc and Wp decrease by 83.5 and 32.1 %, respectively, and the surface free energy (γ) of CFEL film only increases by 8.3 %. The more FA content makes less stable emulsion but have favorable effect on its film properties. When the FA content increases from 0 to 25.11 %, the γ is decreased by 55.1 %. The curing temperature has much impact on film property. For example, the γ from 27.47 to 20.36 mJ · m−2 when the curing temperature rises from 30 to 110 °C.

Correlation between water permeability of latex-modified concrete (LMC) and water diffusion coefficient of latex film

Cement-based materials are generally known as weak materials in flexure and tension in comparison with compression. Polymers are used in cement-based materials to improve their flexural and tensile behaviors. The composite is called as polymer-modified concrete/mortar. Furthermore, polymers decrease permeability of water into cementitious matrices. Polymers are usually used as admixtures in concretes in form of latexes. Latexes are water-based polymers, which are consistent with water-based concrete matrices. On this basis, these kinds of products are called latex-modified concretes (LMCs). However, it has been found that chemical composition, particle size distribution, molecular weight, physical/mechanical properties of latexes affect performance of modified concretes. In this investigation, six latexes in three categories (acrylic, SBR and polyvinyl acetate) were used as concrete admixtures. They were characterized for chemical composition (by FTIR analysis), minimum film formation temperature, pH, glass transition temperature (T g), particle size and particle size distribution to evaluate the effect of each property on LMC performance. Due to the formation of latex film in the microcracks and pores of concrete microstructure, it was suggested that diffusion of water into films controls permeability of whole concrete structures. On this basis, the diffusion coefficient of the latex films subjected to water was measured using a new method (continuous FTIR analysis). Capillary water absorption test was performed on concrete specimens to verify validity of the suggestion. It was found that there is a correlation between capillary water absorption of LMCs and water diffusion coefficient of latex films.

Synthesis and Application of Organic-Inorganic Composite Flexible Architectural Coatings Emulsion

In this study, the organic-inorganic composite elastic latex was prepared by using the polymerization process of pre-emulsification semi-continuous combined monomer dropping and investigated for the effect of the manner of the introduction of inorganic component and the amount of silica on the mechanical properties of the polymer film and water absorption. The results show that, when the sol is introduced with emulsion by the physical blending method and TEOS and A-151 are introduced together, the amount of them are respectively 1.5% and 9%, the organic-inorganic composite emulsion can be prepared. Meanwhile, if SiO2 is added by the way of TEOS and A-151, the best film properties of organic-inorganic acrylate flexible latex will be obtained .

Preparation and Properties of Fluorinated Acrylic Latex Modified with Rosin

The fluorinated acrylic latex modified by rosin was prepared successfully via semi-continuous seeded emulsion polymerization of methyl methacrylate (MMA), butyl acrylate (BA), dodecafluoroheptyl methacrylate (DFMA) and rosin in water phase initiated with potassium persulfate (KPS) and emulsified with the aid of mixed surfactants of SDBS and OP-10. The structure of the resultant latex is confirmed by Fourier transform infrared spectroscopy (FTIR) spectrum. The influences of the amount of rosin on the properties of the resultant latex and its film were investigated in detail. Results show that the conversion and gel percentage is decreased with an increase amount of rosin. However, the particle size and glass transition temperature are increased with the increase amount of rosin.

PDMS-modified poly(styrene-alt-maleic anhydride)s as water-borne coatings based on surfactant-free latexes

In this work, two series of PDMS-modified poly(styrene-alt-maleic anhydride)s (PSMA) were prepared by the partial imidization of their anhydride groups with mono-functional, amine-terminated polydimethyl siloxanes (PDMS-NH2) with two different molecular weights. Subsequently, surfactant-free artificial latexes were prepared and characterized and applied onto cotton fabric. The water contact angle values of the coated cotton fabric indicate the formation of hydrophobic surfaces, with static contact angles varying from 119° to 142° depending on the PDMS loading and PDMS molecular weight. Coatings of the prepared copolymers on cotton fabric are highly durable, as shown by washing studies with a standard soap solution. The properties of these water-based surfactant-free latexes can be tuned easily by changing the composition of the polymers, i.e. mol% of imidization, ammonolysis and cross-linking.

Characterisation and properties of purely acrylic latex with submicro particle size prepared with mixed surfactants of sodium dodecyl benzene sulphonate and allyloxy nonylphenoxy propanol polyoxyethylene ether

The purely acrylic latex with submicro particle size was prepared via semi-continuous seeded emulsion polymerisation of butyl acrylate and methyl methacrylate in water phase initiated with potassium persulphate and emulsified with mixed surfactants of sodium dodecyl benzene sulphonate and allyloxy nonylphenoxy propanol polyoxyethylene ether (ANPPE). The structure of the resultant latex is confirmed with Fourier transform infrared spectroscopy spectrum. Differential scanning calorimetry also confirms that the resultant latex is a type of random copolymer and the consistency among the chain segment is fairly good. Influences of the amount of ANPPE on the properties of the resultant latex and its film were investigated in detail. Results show that the contact angle of the film first is increased and then decreased with the increase of the amount of SN-10. The glass transition temperature of the film is decreased with the increase of the amount of SN-10. However, the particle size of the latex is increased with the increase of the amount of SN-10.

Kinetics of fluorescent latex particle deposition at polyelectrolyte monolayers determined by in situ measurements

A new flow cell was constructed for studying in situ kinetics of particle and macromolecule adsorption using fluorescence microscopy. Using the cell, calibration experiments were performed for fluorescent latex particles on mica coated by cationic polyelectrolytes: polyallylamine hydrochloride (PAH) and poly(diallyldimethylammonium chloride) (PDADMAC). Formation of polyelectrolyte monolayers was controlled via streaming potential measurements in the flow cell. The bulk latex properties were determined by dynamic light scattering (DLS) and microelectrophoresis. The hydrodynamic diameter of particles varied in the range 528–574nm, depending on ionic strength. The electrophoretic mobility measurements revealed that the zeta potential of particles was negative varying between −56mV for I=10−4M, and −42mV for I=0.15M. The kinetics of latex particle deposition at mica coated by saturated polyelectrolyte layers was studied in situ as a function of ionic strength under diffusion-controlled conditions. The coverage was determined by direct enumeration of particles using the fluorescent microscopy and AFM. The experimental results were adequately interpreted in terms of numerical solutions of the mass transport equation with the blocking function derived from the random sequential adsorption (RSA) approach. Additionally, the dependence of integrated fluorescence intensity on particle coverage was determined, which enables a quasi-continuous measurements of particle deposition kinetics. It was concluded that the cell is versatile tool for determining mechanism of particle deposition at interfaces.

Synthesis and surface properties of PDMS-containing latexes by emulsion polymerization using AIBN as the initiator

In this article, a series of PBMA-g-PDMS latexes with high polydimethylsiloxane (PDMS) content up to 60wt% were prepared by emulsion copolymerization of extremely hydrophobic PDMS-macromonomers (PDMS-M) and n-butyl methacrylate (BMA). High yields of PDMS-containing latex particles were obtained and the PDMS-Ms were fully incorporated into the acrylic backbone by using 2,2′-azobisisobutyronitrile (AIBN) as the initiator and sodium dodecyl sulfate (SDS) as the surfactant. The key of successfully incorporating the PDMS segment to the acrylic polymer was the use of the oil-soluble initiator, AIBN, via a miniemulsion mechanism during which no transport of hydrophobic PDMS-Ms through the aqueous phase was needed. Use of a water-soluble initiator like potassium persulfate (KPS) led to particle flocculation and unsuccessful incorporation of PDMS-M in the latex particle. The particle diameter of prepared latexes was 60–170nm, with the polydispersity index (PDI) of 0.1–0.3. All the prepared latexes were very stable, as indicated by the ζ-potential of around −80mV. DSC and GPC results confirmed that PDMS was chemically linked to the PBMA backbone. The advancing water contact angles (CA) on the films from the PBMA-g-PDMS latexes were above 100°, and the receding water CA reached as high as 94°, indicating the film surface was significantly enriched in PDMS. The surface activity of the PDMS-g-PBMA copolymer was further demonstrated by the high water CA on the film from a blend of the copolymer latex and a conventional acrylic latex.

Water-Soluble Substance: Characteristics and Effects on the Properties of Natural Rubber Latex

Water-soluble substance is an important part of non-rubber substance in natural rubber latex and it has significant influence on the properties of natural rubber. The aim of this paper is mainly to study the composition of small-molecular-weight water-soluble substance (s-WSS) and its effects on the properties of natural rubber films. The analysis of IR and HPLC-MS showed that s-WSS (not including sugar) is composed of C3H4N4O6, C7H14O6, C11H13N3O5, C11H20O7 and C6H22N8. While the main component of s-WSS is C7H14O6 whichis a kind of alcohol. The tensile strength of the prepared composites can be increased at low loading of s-WSS. The tear strength of the prepared composites can be improved by adding s-WSS into natural rubber. The thermal oxidation degradation process of the samples has two stages. Compared with neat natural rubber latex, the initial degradation temperature was decreased significantly in both stages when s-WSS was added. While the degradation temperature range became larger in both stages.

Mechanical properties intermaxillary latex and latex-free elastics

BackgroundHypersensitivity to latex is frequently observed in patients undergoing orthodontic treatment. In the search for new alternatives to meet the needs of these patients, latex-free intermaxillary elastics were developed in the 1920s. Although the use of latex-free elastics in dentistry is not new, studies evaluating the mechanical properties of these devices in the literature are scarce. ObjectiveThe aim of this study was to evaluate the mechanical properties of latex and synthetic latex-free intermaxillary elastics. MethodsLatex and latex-free orthodontic elastics, both of 5/16 diameter, were preselected with regard to uniformity of diameter and thickness and were evaluated (n = 17 per group). Initially, the elastics were weighed, and their external diameters at rest were measured. After this, they were taken to a digital dynamometer mounted on a device suitable for measuring initial force. The elastics were kept distended (10 cm) and were immersed into artificial saliva at 37°C. A series of evaluations of force were performed at 2, 6, 8, 12, and 24 hours, and weight and diameter evaluations were repeated at 24 hours. The values for the amount of force released and weight and diameter were analyzed using ANOVA and the Tukey test. ResultsThe latex elastics released statistically greater force than did the latex-free elastics at each time point (all, P < 0.05). The weight of the latex-free elastics did not increase from 0 to 24 hours, whereas the weight of the latex elastics presented a statistical difference (P < 0.05). All of the elastics evaluated had an increase in internal diameter showing permanent deformation (P < 0.05). ConclusionThe intermaxillary latex elastics released greater force and underwent greater degradation than did the latex-free type.

Synthesis of Nanoscale Binders through Mini Emulsion Polymerization for Textile Pigment Applications

Different mini emulsion polymerizations were carried out with the combination of different concentration of anionic surfactant such as sodium dodecyl sulfate (SDS) or hydrophobic alkane such as (hexadecane), and/or different monomer ratios. The best comonomers composition that would lead to the best polymer latex properties to obtain nanoscale polymer latexes was studied. The polymer latexes in a size range between 156 and 65 nm by varying the SDS concentrations from 2 to 6 wt % were obtained, and also the particle size of the obtained polymer latexes decreases with the increases of hexadecane (HD) concentrations, and the best result was obtained with 4 wt % of a hexadecane. The best polymer latex properties in terms of particle size and binder softness were found in the best monomer ratio of BA:MMA:MAA (17.5:1.5:1.5) as the solid content was adapted to be 20%. Higher K/S values and improved crocking fastness are obtained with printing pastes containing prepared binder.

Preparation of low‐allergen natural rubber latex by transglutaminase catalysis

AbstractThe technique of enzyme treatment on the water‐soluble proteins and mechanical properties of natural rubber latex (NRL) films was studied. The main aim was to introduce an enzymic catalysis method to tackle the protein allergy problem in NRL product. The suitable pH value, the temperature, and the best proportion of transglutaminase to deal with NRL were found. The protein spillage of modified NRL films was greatly lower than that of unmodified NRL, and the tensile strength and the elongation at break of the modified NRL films almost had been scarcely changed. The compactness of the NRL films was improved simultaneously. These suggest that the modified NRL can be used as a kind of latex with low‐allergy personal barrier products such as surgical gloves. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The Mechanical Properties of Vulcanized Deproteinized Natural Rubber

Properties of deproteinized natural rubber (DPNR) were investigated in order to apply the DPNR latex as non-allergy vulcanized rubber thin film products. Removal of proteins from natural rubber was made by incubation of high ammonium natural rubber latex (HA-NR) with urea 0.1 wt%, 1 hour in the presence of surfactant at room temperature (DPNR). The nitrogen content of the DPNR was reduced to 0.05 wt%, which was lower than 0.45 wt% of HA-NR under the test condition. The reduction of protein content can be confirmed by observation a chemical structure through FT-IR technique. It is suggesting that the urea treatment is an effective method to remove protein from rubber latex. Then, physical properties of the DPNR latex were investigated. Amount of water soluble protein was observed through modified lowry method and it was found that water soluble protein content after incubation HA-NR with urea was reduced to 15g/g (DPNR) from 4,245g/g (HA-NR). It was found that VFA number of DPNR was lower than that of HA-NR due to lower amount of protein presence in rubber latex. The particle size and charge of rubber latex was examined by dynamic light scattering and zeta potential to compare between un-vulcanized latex and vulcanized latex. The mechanical properties were then observed when we applied the DPNR latex to vulcanized rubber glove.

Experimental investigation of the effect of latex solid/water ratio on latex modified co-matrix mechanical properties

Numerous researches were performed on latex modified concretes and associated properties, however; some vital factors were not given attention in previous works. This study focus on new factor which significantly affects the properties of latex modified cement paste, mortar or concrete. This factor is termed as ‘latex solid/water ratio’ which is defined herein as the ratio of weight of solid latex to weight of total water content of cement composite including the water in latex itself. The effect of this factor on some properties of cement paste, mortar and concrete were experimentally evaluated. Properties of cement paste include the produced calcium hydroxide and ettringite content during hydration process, while those of cement mortar take account of absorption and effect of temperature on compressive strength. Furthermore, the effect of this factor on the compressive and flexural strengths, modulus of elasticity, water penetration depth and drying shrinkage of concrete were explored. Based on experimental evidences, and spite of using different cement contents, sources of latex, water–cement ratios and slump values, it can be generally concluded that the latex solid/water ratio is a dominant factor affecting different properties of latex modified mortars and concrete.

Synthesis of fluorine-containing latexes with core–shell structure by UV-initiated microemulsion polymerization

A core–shell structure of fluorine-containing polyacrylate latex was synthesized by UV-initiated two-stage microemulsion polymerization from styrene (St) and hexafluorobutyl acrylate (HFA) in the presence of Irgacure 2959 as hydrophilic photoinitiator at room temperature. The first polymerization stage took 12 min and the second stage took 10 min. The conversions of the first and the second polymerization stages were about 60 and 85 %, respectively. Fourier transform infrared (FTIR) spectra, transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and contact angle analysis were used to characterize the properties of latexes and their films. The DLS analysis results indicated that the size of the fluorine-containing nanoparticle is about 20 nm. The TEM photos showed that the particles have core–shell structure and some of the cores are located in the center and the others deviate from the center of particles. From the FTIR and XPS results, we can infer that the fluorine monomer could be introduced into the copolymer and the fluorine-containing polyacrylate mainly occupies the shell part. The TGA results indicated that the fluorine-containing polyacrylate copolymers exhibited higher thermal stability than that of the fluorine-free one. The contact angle analysis results showed that fluorine monomers make the film surface more hydrophobic.

Preparation and Properties of Anionic Polymer Emulsion in the Presence of a Reactive Surfactant

Stable polymer emulsion derived from Butyl Methacrylate (BMA), 4-vinyl pyridine (4-VP), vinylidene chloride (VDC) and divinylbenzene (DVB) with different size and distribution were prepared through soapless emulsion polymerization by using a reactive surfactant and a redox initiator. The influences of the quality ratio of the reactive surfactant to the monomers and the dosages of the cross-linking agent on the stability and thermal properties of the emulsion were studied. The obtained polymer nano-particles have higher ξ potential, and the particle sizes have narrow distribution. This polymerization system can give some further understanding on the mechanism of emulsion polymerization .The solid content of the emulsion could be as high as 40% and the particle sizes could be adjusted in the range of 40-300nm. Otherwise, using infrared spectroscopy, size and ξ analyzer, gravitational thermal analysis and differential scanning calorimeter, properties of the emulsion latex were tested. This kind of latex may have applications in the development of water-developable thermal-sensitive material system.

Advanced functionalization of organoclay nanoparticles by silylation and their polystyrene nanocomposites obtained by miniemulsion polymerization

Four types of alkoxysilanes with different organosilyl groups were used for the silylation of a commercial alkylammonium-modified montmorillonite (Cloisite 30B). TGA, XPS, DLS, FTIR, XRD, and contact angle measurements were performed for the characterization of the silylated clays. Furthermore, the behavior of these advanced hydrophobic clays in the miniemulsion polymerization process of styrene and the characterization of nanocomposites materials were followed. The hydrophobic nature is a combined result of the length of the organic chain and of the amount of silane groups grafted onto clay edges, reflected also in the final properties of the nanocomposite latexes.

Preparation of Covalently‐colored Polymer Latex via Batch Emulsion Polymerization

AbstractCovalently‐colored polymer latex was synthesized via batch emulsion copolymerization of styrene, butyl acrylate and methacrylic acid in the presence of red polymerizable dye monomer consisting of anthraquinone chromophore, alkyl spacer and acryloyl group, and the influences of the initiator, surfactant and polymerizable dye on the polymerization and the latex properties were investigated. Results showed that the initiator amount was a determinative factor for the monomer conversion, and a high conversion of the polymerizable dye could be achieved when the ammonium persulfate amount was equal to or more than 1 wt% to the total monomers. Most of the chromophores were covalently bonded to the polymer chains if the polymerizable dye was used in the range of 0–1.5 wt%. The light fastness of the resulting latex film was much better than that of the noncovalently‐colored polymer film.