Butadiene Styrene Polymer Research Articles

Computed tomography: an evaluation of the effect of adding polymer SBS to asphaltic mixtures used in paving

This work applies the Computed Tomography (CT) technique to the study of asphaltic mixtures to which polymer has been added. An evaluation has been made of the effect of adding Brazilian produced polymer SBS (styrene–butadiene–styrene), to the asphaltic mixtures used in paving. Laboratory mechanical tests and non-destructive testing (NDT) of cylindrical specimens have been made. Three mixtures were prepared for the purpose of this study, all containing 5.4% of asphalt RASF (propane deashalting). One of the mixtures contained no polymer, while the other two were made with 7 and 5% of the SBS polymer. Investigations of Brazilian pavements have shown that cracking is the most important defect due to fatigue in the asphaltic contained overlay. Preliminary results of mechanical tests show that the polymer additive favorably enhances performance of the mixtures. It may be noted that adding polymer SBS to the asphaltic mixture used in paving increases the percentage void. Crack growth in specimens of asphaltic mixtures to which polymer has been added displays the same behaviors as that in specimens in which polymer has not been added.

Mechanistic Evaluation of Hydrated Lime in Hot-Mix Asphalt Mixtures

Permanent deformation and moisture damage are common distresses found in pavements today. The use of mineral fillers such as hydrated lime is known to provide a decrease in moisture susceptibility. In many cases, mineral fillers will also increase the mixture stiffness. Conventional asphaltic concrete mixtures and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by indirect tensile strength and strain, permanent deformation characteristics, resilient modulus, and fatigue resistance. A typical Louisiana low-volume dense-graded mixture was used. The test factorial included two aggregate types (limestone and gravel) and two asphalt cement types (a conventional AC-30 and one modified with styrene-butadiene polymer). The results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue endurance of the asphaltic concrete mixtures. This improvement was particularly apparent at higher testing temperatures with mixes containing polymer-modified asphalt and limestone aggregate.

Flocculation of Sludges of Sulfide Minerals by a Hydrophobic Polymer

A study is made for the influence of hydrophobic butadiene-styrene polymer SKS-30 OKh on the flocculation and flotation of sludges containing chalcopyrite, pyrite, and sphalerite. It is established that the effect of the polymer increases when the sludges are first hydrophobized with xanthate.

Rheology of acrylonitrile–butadiene–styrene polymer melts and viscoelastic constitutive models

Experimental shear and tensile stress growth coefficients for startup of steady shear and uniaxial elongation for a commercial grade acrylonitrile–butadiene–styrene (ABS) polymer melt are presented. One differential [Phan-Thien and Tanner (PTT)] and two Kaye–Bernstein–Kearsley–Zapas (K-BKZ) type single integral [Wagner and Papanastasiou–Scriven–Macosko (PSM)] nonlinear viscoelastic constitutive models were fit to shear and extensional experimental data. A comparison of the fit quality was performed, and the PTT model was found to result in the best overall quality fit, although deviations from linear viscoelastic behavior at small extensional strains could not be adequately described by the linear viscoelasticity theory without a time correction. Experimental data for stress relaxation after cessation of both steady shear and uniaxial elongation were compared with three constitutive model predictions in order to evaluate their anticipated accuracy in the prediction of residual stresses. The PTT model provided better predictions of ABS relaxational behavior than K-BKZ models except for shear stress relaxation in the nonlinear regime. Qualitative differences between experimental data and model predictions were found to be present for all models tested at large shear and extensional strains.

Analysis of a 15% Glass-filled Acrylonitrile Butadiene Styrene Polymer by XPS

We report x-ray photoemission spectra for a 15% glass-filled acrylonitrile butadiene styrene (ABS) polymer. XPS spectra were acquired with a SSI model SSX-100 instrument, using monochromated Al Kα x-rays. We present the survey spectrum (binding energy 0–1000 eV) and a narrow spectrum of the C 1s, O 1s, and N 1s photoelectron peaks.

Phase Separation of SBS Polymer Modified Bitumens

Styrene-butadiene-styrene (SBS) polymer modified binders consist of two-phase (polymer-rich and asphaltene-rich) mixtures. This type of system is thermodynamically unstable, and a phase separation may occur under the influence of gravitational fields. In this study, the phase separation was determined by a hot storage test and characterized using the softening point, dynamic mechanical analysis (DMA), and Fourier transform infrared (FTIR) spectroscopy. Based on DMA and FTIR, influences of the type of base bitumen and the characteristics and concentrations of SBS polymers were studied. In addition, the rheological properties of the separate phases were investigated, and the mechanism of phase separation was discussed.

Chemical and Rheological Characteristics of Styrene-Butadiene-Styrene Polymer-Modified Bitumens

Styrene-butadiene-styrene (SBS) polymer-modified bitumens were prepared in the laboratory and characterized using rheological and chemical methods. The results showed that morphology of the modified binders was influenced by bitumen composition and polymer content. Polymer modification was found to improve the rheological properties of bitumens. The degree of modification was dependent on the base bitumen and SBS content and structure. It was also observed that aging resulted in degradation of the SBS polymer. Changes in the rheological properties of aged modified binders were dependent on a combined effect of bitumen oxidation and polymer degradation, which varied with the source and grade of bitumen and type and content of polymer. Generally, the aged modified binders showed better rheological properties than aged base bitumens. The study also indicated that aging index is not suitable for evaluating the aging susceptibility of polymer-modified binders.

Low-temperature properties of styrene–butadiene–styrene polymer modified bitumens

Low-temperature properties of the modified bitumens containing styrene–butadiene–styrene (SBS) polymers were investigated using conventional methods, dynamic mechanical analysis (DMA) and bending beam rheometer (BBR). Effects of the characteristics of base bitumens and polymers and the proportion of the components on these properties were studied. The results indicated that SBS polymers improved low-temperature properties of bitumens. The degree of improvement generally increased with SBS content and were influenced slightly by SBS structure. The study also showed a statistically linear relationships between different low-temperature parameters.

Chemical and rheological evaluation of ageing properties of SBS polymer modified bitumens

The ageing properties of Styrene-Butadiene-Styrene (SBS) polymer modified bitumens were evaluated using Dynamic Mechanical Analysis (DMA), Gel Permeation Chromatography (GPC) and Fourier Transform InfraRed (FTIR) spectroscopy. The binders were aged by means of the Thin Film Oven Test (TFOT) and the Rolling Thin Film Oven Test (RTFOT), respectively. It was observed that ageing resulted in degradation of the SBS polymer (decrease in the polymer molecular weight) and oxidation of the bitumen (increase in the content of polar oxygen-containing molecules and increase in bitumen molecular weight). The polymer was observed to resist formation of sulphoxides. Changes in the rheological properties of aged-modified binders were dependent on a combined effect of bitumen oxidation and polymer degradation, which varied with bitumen source/grade and polymer type/content. In all cases, the aged modified binders showed better rheological properties than aged base bitumens. The study also indicated that the ageing index obtained using DMA was largely influenced by temperature and frequency. This parameter may be applied for evaluating the base bitumens and modified binders with a low polymer content (3% in this study), but not for modified binders with a high (6%) polymer content.

Effects of Dazomet-Granular Fumigant and Mulch for the Production of ‘Sunny’ Tomato

ABSTRACT 'Sunny' tomato plants were grown, using four fumigant treatments and three mulch treatments. Fumigants were metham sodium at the rate of 935 l/ha and dazomet at rates of 336 kg/ha, 420 kg/ha and 504 kg/ha. Mulches were 1.25 mil black polyethylene (plastic), a spray-on styrene-butadiene polymer dispersion (Styrofan) sprayed over beds at a rate of 959 l/ha, or none. Plants in all mulch treatments produced similar marketable yields. Neither fumigant had an advantage over the other in yield.

Syntheses and gas‐transport properties of alkylsilane‐modified SBS membranes

Alkylsilane-modified styrene-butadiene-styrene (SBS) polymers were prepared via two steps. In the first step, dimethylchlorosilane HSi(CH3)2Cl and SBS (Korea Kumho Petrochem. Co.; 35% vinyl content; Mo = 48,000, Mo/Mn = 1.05) were reacted in toluene using H2PtCl6 catalyst to produce a hydrosilylated polymer. In the second step, chloride in the silyl group was replaced with alkyl by reaction with RLi (R = Me, n-Bu). Under severe conditions, silylation occurs on all the double bonds of the polymer so that their elastomeric nature disappears. However, under mild conditions, selective hydrosilylation of the pendant vinyl groups of SBS could be accomplished so that the polymer retained its elastomeric properties with two low Tg values. These modified SBS polymers were easily dissolved in THF, and thus could be formed into film-type membranes by solvent casting on teflon plates. From the measurements of their gas permeability for O2 and N2, they showed higher selectivity for O2 compared with the unmodified SBS. The permeability for oxygen was dependent on the size of the alkylsilyl group. Methylsilane and butylsilane-modified SBS membranes showed the higher permeability values of 31.2 and 37.5 barrer (1 barrer = 1 × 10−10 cm3 (STP) cm cm−2 s−1 cmHg−1) at 30°C, respectively, compared with 2.39 barrer of the unmodified SBS. Furthermore, their selectivities for O2 over N2 were increased to 3.0 and 3.2, respectively, from 2.5 of the unmodified SBS case. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1117–1122, 1997

Syntheses and gas-transport properties of alkylsilane-modified SBS membranes

Alkylsilane-modified styrene-butadiene-styrene (SBS) polymers were prepared via two steps. In the first step, dimethylchlorosilane HSi(CH3)2Cl and SBS (Korea Kumho Petrochem. Co.; 35% vinyl content; Mo = 48,000, Mo/Mn = 1.05) were reacted in toluene using H2PtCl6 catalyst to produce a hydrosilylated polymer. In the second step, chloride in the silyl group was replaced with alkyl by reaction with RLi (R = Me, n-Bu). Under severe conditions, silylation occurs on all the double bonds of the polymer so that their elastomeric nature disappears. However, under mild conditions, selective hydrosilylation of the pendant vinyl groups of SBS could be accomplished so that the polymer retained its elastomeric properties with two low Tg values. These modified SBS polymers were easily dissolved in THF, and thus could be formed into film-type membranes by solvent casting on teflon plates. From the measurements of their gas permeability for O2 and N2, they showed higher selectivity for O2 compared with the unmodified SBS. The permeability for oxygen was dependent on the size of the alkylsilyl group. Methylsilane and butylsilane-modified SBS membranes showed the higher permeability values of 31.2 and 37.5 barrer (1 barrer = 1 × 10−10 cm3 (STP) cm cm−2 s−1 cmHg−1) at 30°C, respectively, compared with 2.39 barrer of the unmodified SBS. Furthermore, their selectivities for O2 over N2 were increased to 3.0 and 3.2, respectively, from 2.5 of the unmodified SBS case. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1117–1122, 1997

Influence of styrene-butadiene-styrene polymer modification on bitumen viscosity

Effects of polymer content/structure and bitumen type on viscosity characteristics of styrene-butadiene-styrene (SBS) polymer modified bitumens were investigated. The study indicated that SBS polymers were not inert additives and increases in kinematic and dynamic viscosities of the modified bitumens were not directly proportional to polymer content; a marked viscosity increase was observed when the polymer content increased from 3 to 6% by weight of the blend. Modification with a sufficiently high polymer content also increased the degree of non-Newtonian behaviour of the bitumens. The base bitumens and modified bitumens containing 3% SBS were observed to be essentially shear rate independent, while those containing 6 or 9% SBS displayed shear-thinning behaviour. Compared to the modified bitumens with linear SBS, the modified bitumens with branched SBS demonstrated a higher degree of shear-thinning behaviour. These effects were dependent on ranges of shear rate and temperature. The increased degree of non-Newtonian behaviour was observed to influence the correlations between kinematic and dynamic viscosities.

Styrene-Butadiene Polytelomers for Pressure-Sensitive Applications

Novel styrene-butadiene polymer latex compositions and their utility for pressure-sensitive and other adhesive applications are described. These compositions, termed polytelomers, are based on the concept of synthesising sequentially a low glass transition temperature, high molecular weight (polymeric) fraction, followed by a high glass transition, low molecular weight (telomeric) fraction, in an attempt to simulate the compounding of elastomeric adhesives. Some of the described compositions can exhibit multiphase morphology, having discrete styrene-rich domains surrounded by butadiene rich phase, both of these phases being embedded in a “honeycomb” carboxyl-rich phase. The compositions were characterized by dynamic mechanical spectroscopy and by electron transmission microscopy, as well as by molecular weight distribution and glass transition temperature range data. Examples of adhesive applications are also given.

The Maximum Peel Strength of Pressure-Sensitive Styrene-Butadiene Emulsion Polymers

Peel strengths of five pressure-sensitive styrene-butadiene emulsion polymers, having different amounts of gel and different glass transition temperatures, have been determined as a function of temperature and peel rate. For each peel rate, the peel strength reaches a maximum at a particular temperature, and this maximum peel strength is associated with the change of the mode of failure from cohesive to adhesive. The maximum peel strength is found to be largely independent of the gel level and possibly of the glass transition temperature of the polymer within the domain of pressure-sensitive polymeric properties. The maximum peel strength appears to be dependent on the kind of substrates and the stabilization system of the emulsion polymers (surface free energy properties of the bonded interfaces).

Influence of short-fibre reinforcement on the mechanical and fracture behaviour of polycarbonate/Acylonitrile Butadiene Styrene polymer blend

The present study investigated the dependence of various mechanical and fracture properties on the volume fraction, φf, of the reinforcing glass fibres in Polycarbonate/Acylonitrile Butadiene Styrene (ABS) blends. The addition of glass fibres enhanced the ultimate tensile strength and modulus and reduced elongation (both to yield and to break) and total work of fracture. The elastic modulus was not significantly affected by the loading mode although the ultimate strength was significantly affected, giving flexural strength values of 1.5–1.6 times greater than tensile strengths. The elastic modulus and strength were linear functions of φf and thus followed the principle of rule of mixtures. The presence of weldlines in specimens had an adverse effect on most tensile properties except for the elastic modulus. Linear elastic fracture mechanics could not be used to assess the resistance to crack propagation of the present range of materials because their behaviour violated the principle assumptions upon which the theory is based. An alternative method was employed where the total work of fracture and the work of fracture corresponding to the maximum load were plotted as a function of initial crack length. These plots were reasonably linear for the polymer and its composites giving values of the resistance to steady state crack propagation JT and the J integral of maximum load Jm respectively. Values of JT and Jm decreased with increasing φf.

Fumigation and Mulch Affect Yield, Weight, and Quality of 'Pimiento L' Pepper, Capsicum annuum L

Treatments were metham sodium at 1114 and 2228 liters ha-'; 67% methyl bromide, 33% chloropicrin (MB-67) at 392 kg ha-'. 98% methyl bromide, 2% chloropicrin (MB-98) at 450 kg ha-' ahd non-fumigated. Mulch treatments were 31.5 mm thick black polyethylene plastic a spray-on styrene-butadiene polymer dispersion (Styrofan) sprayed over beds at 959 liters ha-', and unmulched. Styrofan and plastic mulch increased marketable pepper yield similarly, compared to the unmulched control. Metham sodium at 1114 liters produced the highest marketable yield of the 5 fumigant treatments.

Dynamic mechanical analysis and water sorption of some experimental elastomeric soft lining materials

This research was undertaken to develop a better understanding of the relationships among the compositions, structures and properties of denture soft liners. Five butadiene-styrene-acrylic elastomers were prepared. They were prepared using 50% of powdered prepolymerized butadiene-styrene polymer combined with 50% of a methacrylate monomer (HMA or EHMA) plus varying amounts of initiator and crosslinker. The mixtures were gelled and processed conventionally. Specimens were then committed to dynamic mechanical analysis and water sorption. Dynamic mechanical analysis was performed over the temperature range 5–95°C at the rate of 2.5°C/min using a Perkin Elmer DMA-7 with 3 mm flat tip probe at 1 Hz. Wet and dry values for storage modulus (E') and damping factor (tan δ) were determined at 37°C. Water sorption of these butadiene styrene elastomer-acrylic systems from solutions of varying concentrations was measured in order to establish the role of osmotic pressure. Diffusion coefficient (D d) was determined from the desorption values. The relatively lower values of D d observed in most highly concentrated solutions particularly 1 m sodium chloride and glucose may be interpreted as related to reduced water sorption from these solutions. Increasing crosslinking increased the modulus and decreased water sorption. Using hydrophobic EHMA instead of HMA reduced water uptake, reduced dry modulus and reduced the decrease in modulus caused by water sorption. Dynamic moduli and water sorption generally exceeded those of the commercial materials studied. For all experimental materials, water uptake from saline and glucose solutions confirmed that the diffusion process is osmotically driven.

Structural changes upon annealing in a deformed styrene-butadiene-styrene triblock copolymer as revealed by infrared dichroism

Structural and morphological changes in a deformed styrene-butadienestyrene (SBS) tri- block copolymer were usually studied by means of small-angle X-ray scattering techniques through analysis of scattering patterns which are related to rigid polystyrene (PS) microdomains. In the present study, a different approach was demonstrated. Infrared dichroism was used to elucidate these changes induced by annealing through measurements of molecular orientation of rubbery polybutadiene (PB) chains. This was made possible by the fact that (1) structural rearrangements of PS microdomains are inevitably associated with changes of the PB orientation and (2) strain-induced orientation of the PB chains depends on the arrangement or orientation of the PS microdomains which act as cross-links. Infrared dichroism analysis showed that the relaxation of rigid PS microdomains, which occurs even at annealing temperatures (T,) below the glass transition temperature (T,) of PS, can be studied by observing the relaxation of the PB orientation and that the remaining PB orientation under constant strain at long annealing time (>30 min) characterizes the orientation of rubbery chains required for activating PS plastic flow. Furthermore, it was found that the loss of PB orientation under strain with annealing time is not equally associated with the lost recovery of the sample length after removal of the extensional stress, suggesting the existence of different mechanisms of PB orientation relaxation. Finally, an anisotropic morphology in annealed SBS polymer was revealed by a strain-induced PB orientation which depends on the redrawing direction with respect to the initial stretching direction (SD). These measurements indicate that, at Ta 5 Tg of PS, the PS rearrangement involves essentially rotation of cylindrical microdomains, with the interdomain vector connecting the centers of the cylinders remaining preferentially parallel to the SD; while, at T,, > Tg of PS, the rearrangement process involves more displacement of the PS cylinders, with the interdomain vector oriented perpendicularly with respect to the SD.

Immediate reactions to rubber products.

There is an increasing incidence of contact urticaria (CU) and systemic reactions to rubber products. Thirty-one patients are presented: most were atopic (20/31) and women (26/31); 71% worked in the medical field; 32.2% (10/31) showed signs of hand dermatitis. In 28 patients (90.3%), rub and/or prick tests with liquid latex in different dilutions and with latex gloves led to an immediate type of positive reaction. The allergen(s) appear in part to be water soluble: 20 of 28 patients (71.4%) revealed positive test reactions to an aqueous glove extract. In two patients, urticarial test reactions to tetramethylthiuram disulfide (TMTD), mercapto mix, and p-phenylenediamine (PPD mix) were considered as possible contributing factors of CU. Cornstarch was negative in all patients (scratch). Sixteen of 27 sera (59.2%) showed radioallergosorbent (RAST) class 0 using latex allergen disks. Sodium dodecyl sulfate-polyacoyl-amide (SDS-PAGE) determined protein bands of less than or equal to 14 kD (not allergen specific) and approx 28 kD. The Western blot detected the 28 kD protein as allergen in the sera of three patients. Isoelectric focusing (IEF) proved no protein bands. Immunoprinting performed with sera of five patients presented allergen bands in a pH range between 3.8 and 4.55. This shows the radio staining (immunoprint) is more sensitive than is the Coomassie blue staining. Although three sera showed RAST class 0, immunoblotting detected allergen bands. In this case the immunoblot appears to be more sensitive than the RAST. A cross reactivity between latex and banana could not be established. Alternative gloves are Neolon (neoprene) or Elastyren (styrene-butadiene polymer).