Liquid Polybutadiene Research Articles

Characterization of nanostructured epoxy networks modified with isocyanate-terminated liquid polybutadiene

Polybutadiene-block-epoxy prepolymer (DGEBA-b-PBNCO) copolymers with multi-branched topological structure were prepared by reacting isocyanate-multifunctionalized liquid polybutadiene (PBNCO) with DGEBA prepolymer and used to develop nanostructured rubber-modified epoxy thermosets cured with triethylene-tetramine (TETA) as the aliphatic amine. The nanoscopic structure was obtained with the addition of as high as 20 phr of rubber component and successfully demonstrated by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). The glass transition temperature of the rubber-modified epoxy networks was slightly higher than the neat epoxy system. In addition, a unique combination of outstanding toughness and increased modulus and T g was achieved in these modified systems, which was attributed to the peculiar morphology associated with a strong interfacial adhesion imparted by the reaction between the isocyanate and hydroxyl groups present in the PBNCO and epoxy resin, respectively. The effect of the PBNCO on the gelation time of the epoxy/TETA system was investigated by rheological techniques. The NCO-functionalized polybutadiene decreased the gelation time, indicating an accelerating effect on the curing process, probably because of the urethane groups formed by the reaction between PBNCO and the epoxy resin during the PB-b-ER block copolymer preparation.

Modification of Silica by Liquid Polybutadienes Containing Alkoxysilane Groups

AbstractSummary: The present work describes a method to modify the surface of silica, reducing its polar character and making it compatible and dispersible into hydrocarbon based elastomers. A liquid low molar mass polybutadiene (PB) was grafted with mercaptopropyltrimethoxysilane (MPTS) via radical addition of the thiol group to the double bonds. The silanized PB was reacted with silica via thermal condensation with its silanol groups. 29Si NMR spectra showed that the condensation reaction of the trifunctional silane involved one or two alkoxy groups, while the third alkoxy group remained unreacted, probably for steric reasons. The characterization of the functionalized silica particles was performed by contact angle measurements and TGA analysis.

Synthesis and characterization of star-comb styrene/butadiene copolymer

A novel star-comb styrene/butadiene copolymer (SC-SBC) was synthesized by anionic polymerization and grafting reaction with epoxidized star liquid polybutadiene (ESPB) as coupling agent. The overall shape of the star-comb macromolecules can be altered by changing the molecular weight and number of the side chain. The molecular parameters and mechanical properties of the SC-SBC resins were investigated. The notched izod impact strength of the SC-SBC resins are excellent and reach as high as to 239 J/m.

Mechanical properties and thermal aging behavior of styrene‐butadiene rubbers vulcanized using liquid diene polymers as the plasticizer

AbstractThe mechanical properties of styrene‐butadiene rubber (SBR) vulcanizates prepared using various plasticizers including liquid polybutadiene and styrene‐butadiene copolymers were investigated. The effect of the liquid polymers as the plasticizers on the mechanical properties of the polymers, such as the hardness, tensile storage modulus, tanδ, and the modulus at 100% elongation values, were determined before and after the thermal aging. As a result, it was revealed that the use of these liquid polymers gave less amount of change in the measurement values for the mechanical properties during the aging. The crosslinking density and the amount of free polymers were also determined on the basis of the swelling and extraction data, respectively, using several organic solvents. These results support the fact that the added liquid polymers are fixed to the SBR networks. We revealed the superiority of the liquid styrene‐butadiene copolymers as the plasticizer, which provides sufficient mechanical properties after vulcanization and the excellent maintenance of the properties during the thermal aging process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Structure, mechanical properties, and gas permeability of elastomers based on polybutadiene and epoxy resin

AbstractIn this study, the structure, gas permeability, and mechanical properties of new elastomers based on liquid polybutadiene and epoxy resin were investigated by dynamic mechanical thermal analysis, thermogravimetric analysis, stress–strain analysis, and water‐resistance and gas permeability tests. The results reveal that there was complete phase separation between the epoxy resin and polybutadiene. With increasing epoxy resin content, the glass‐transition temperature of the soft segment varied little. These elastomers had tensile strengths of 6–10 MPa and ultimate elongations of 500–100% according to the different epoxy resin contents. Thermogravimetric analysis revealed that these elastomers had better thermal stability, with a 5% weight loss at a temperature of around 350°C. The gas permeabilities of these elastomers were measured to be 13.2–15.3 barrers for oxygen, 4.8–5.3 barrers for nitrogen, and 28–35 barrers for carbon dioxide at 23°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

A rheological method for selecting nano-kaolin powder as filler in SBR rubber

This paper shows that the stiffness of styrene–butadiene solid rubber with added kaolin powder is related to the yield stress of kaolin dispersion in liquid polybutadiene rubber up to the percolation threshold. For five kinds of kaolin powder, the value of τ° spans the range of 100–430 Pa, while the corresponding compressive elastic constant of SBR varies from 12 to 21 MPa. A relationship between τ° and Δ E i * / E R * is proposed. Critical examination of these data infers that kaolin powder dispersed in solid rubber matrix acts as an additive which decreases the random movement of the polybutadiene chains. Consequently, dispersions of nano-particles in liquid and in solid SBR are considered to be related, thus leading to a rheological method for selecting nano-particles as fillers in solid SBR.

Studies on the extraction of chromium(III) by emulsion liquid membrane

This paper presents a comprehensive study on removal of chromium(III) from aqueous waste solution using emulsion liquid membrane (ELM). The study has highlighted the importance of emulsion stability for maximizing the removal of chromium(III). The ELM consists of tri-n-butyl phosphate (TBP) as a carrier, commercial kerosene as organic solvent, sulfonated liquid polybutadiene (LYF) as surfactant agent, sulfuric acid, deionized water or sodium hydroxide as stripping phase. The important factors studied which affected the ELM stability and removal of chromium(III) were the concentrations of surfactant (2-8% w/w), carrier (2-10% w/w), internal phase H(2)SO(4) [pH 0-6], deionized water [pH 6.65] and NaOH (0-0.8% w/w), transfer time (5-35 min) and the effect of volume ratio of the feed solution to the emulsion phase (Rf) (5:1-9:1). At the optimum condition it was possible to remove 99.71-99.83% of chromium(III) by using ELM. LYF was not only the surfactant but also played a key auxiliary effect for TBP combining with chromium(III) by studying on the transport mechanism.

Synthesis and characterization of star-comb polybutadiene and poly(ethylene-co-butene)

A novel star-comb polybutadiene (SC–PB) was synthesized with n-butyllithium ( n-BuLi) as initiator, epoxidized star liquid polybutadiene (ESPB) as coupling agent, cyclohexane as solvent by living anionic polymerization and grafting-onto technology. The SC–PB was subsequently hydrogenated by homogeneous catalysis (catalytic hydrogenation using nickel naphthenate/triisobutyl aluminum), to transform the SC–PB into the corresponding star-comb poly(ethylene- co-butene) (SC–PEB). The SC–PB was characterized by SEC-TALLS, 1H NMR, DSC and WAXD techniques. The hydrogenation degree and crystallinity degree of SC–PEB were also determined.

Mechanical properties of styrene–butadiene–styrene block copolymer composites filled with calcium carbonate treated by liquid polybutadienes

AbstractThe factors influencing the mechanical properties of styrene–butadiene–styrene block copolymer (SBS) composites filled with liquid polybutadiene (LB)‐surface‐treated calcium carbonate (CaCO3) were investigated with respect to the molecular structure of the LB, the amount of the LB adsorbed on the CaCO3 surface, the heat treatment conditions, and the surface treatment method. The mechanical properties, such as the modulus, tensile strength at break, tear strength, storage modulus, and tension set, of the SBS composites were improved remarkably through the filling of CaCO3 surface‐treated with a carboxylated LB with a high content of 1,2‐double bonds. The heat treatment of LB–CaCO3 in air was also effective in enhancing such properties. When SBS, CaCO3, and LB were directly blended (with the integral blend method), secondary aggregation of CaCO3 took place, and the mechanical properties of the composite were significantly lower. In the integral blend method, LB functioned as a plasticizer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Thermodynamic study of surfaces of liquid polybutadienes and their interfaces with poly(dimethylsiloxane)

AbstractSurface tension of liquid polybutadienes (PBD) as well as interfacial tension between them and poly(dimethylsiloxane) (PDMS) were measured in the temperature range from 25 to 150°C. The measured pressure–volume–temperature (PVT) data were used for the determination of reduction parameters of pressure, volume, and temperature in several equations of state for polymers. The reduction parameters were used for the estimates of surface tension and compared with experimental data. Interfacial tensions were used to determine Flory‐Huggins interaction parameters using the Roe and Helfand theories for the system PBD‐PDMS. The results obtained using both the theories were somewhat different; the difference being the least with the segment chosen as a part of molecule containing 4–5 nonhydrogen atoms.Modifications of PBD that were investigated increase the density. Maleic ester end groups increase both surface tension and interfacial tension and bring a positive contribution to the Flory‐Huggins interaction parameter (to its enthalpic component), whereas the pending maleic anhydride groups have shown the opposite effect; their negative contribution to Flory‐Huggins parameters concerns mainly its entropic component. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis, Characterization and Application of Coatings Based on Epoxy Novolac and Liquid Rubber Blend

Phenol‐based novolac resins were synthesized with different mole ratios of phenol‐to‐formaldehyde. These novolac resins were epoxidized with molar excess of epichlorohydrin at 120 °C in basic medium. Novolac and epoxy novolac resin were characterized by FTIR, NMR and GPC analysis. Molecular weight was found to be 838. The epoxidized novolac resins were separately blended with different weight ratios of carboxyl‐terminated polybutadiene liquid rubber ranging between 0‐25 wt % with an interval of 5 wt %. All the blends were cured at 150 °C with 40 wt % polyamide. The cured films of blend samples were checked for use them in coating applications.

Pseudo‐Living Anionic Telomerization of Buta‐1,3‐diene

AbstractLow‐molecular‐weight liquid polybutadienes (1 000–2 000 g · mol−1) consisting of 60 mol‐% poly(buta‐1,2‐diene) repeating units were synthesized via anionic telomerization. Maintaining the initiation and reaction temperature at less than 70 °C minimized chain transfer and enabled the polymerization to occur in a living fashion, which resulted in well‐controlled molecular weights and narrow polydispersity indices. MALDI‐TOF mass spectrometry confirmed that the end groups of liquid polybutadienes synthesized via anionic telomerization contained one benzyl end and one protonated end. In comparison, the end groups of liquid polybutadienes synthesized via living anionic polymerization contained one sec‐butyl or butyl end and one protonated end.magnified image

Macromol. Chem. Phys. 19/2008

Cover: The cover image shows the brief reaction scheme of well‐defined low molecular weight liquid polybutadienes via anionic telomerization. As can be seen from the monodisperse peak in the SEC curve (right) and the MALDI‐TOF MS spectrum (left), a controlled reaction temperature and reaction procedure minimizes chain transfer and enables the polymerization to occur in living fashion. Further details can be found in the article by T. Saito, K. C. Harich, and T. E. Long* on page 1983.

An effective way to stabilize silicon nitride nanoparticles dispersed in rubber matrix by a one-step process

In this work, a new graft copolymerization macromolecular coupling agent (LMPB- g-MAH) of maleic anhydride (MAH) onto low-molecular-weight polybutadiene liquid rubber (LMPB) was synthesized, and it was used to modify silicon nitride nanoparticles (Si 3N 4). The structure and surface properties of modified nano-Si 3N 4 were systematically characterized by FTIR, TEM, XPS, size distributions analyzer, TGA, dispersion stabilization in dimethylbenzene and contact angle measurement. It can be found that the optimum graft degree (GD%) and loading of LMPB- g-MAH is 9–11% and 10–12%, respectively. According to the spectra of FTIR and XPS, it can be inferred that LMPB- g-MAH covalently bonds on the surface of nano-Si 3N 4 particles and an organic coating layer was formed. The contact angle and surface free energy experiments show that the hydrophobic property of modified nano-Si 3N 4 is improved. TEM reveals that modified nano-Si 3N 4 possesses good dispersibility and the average diameter in dimethylbenzene is less than 60 nm. TGA indicates that the using efficiency of the macromolecular coupling agent is 44.66%. The oil resistance of SBR-based nanocomposites was also studied, which was improved greatly due to the modified nano-Si 3N 4.

A new chemical modification of liquid polybutadienes: Radical addition of aliphatic aldehydes onto pending vinyl groups

AbstractA new chemical modification of liquid polybutadiene by radical addition of model aldehydes (butanal and hexanal) onto pending vinyls of the polymer is described. The dibenzoyl peroxide/N,N‐dimethylaniline redox system was shown to initiate the hydroacylation more efficiently than the thermal decomposition of 2,2′‐azobis(2‐methylpropanenitrile) because it gives higher conversions (content of hydroacylated monomer units, as determined by NMR) without forming crosslinks or microgels. Typically, the former source of radicals gives the content of modified units as high as 13% related to all monomer units, while the latter only 2–6%. Repeated introduction of the redox system into the reaction mixture resulted in an increased content of the acyl groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3919–3925, 2008

Study of surface modification of nano-SiO2 with macromolecular coupling agent (LMPB-g-MAH)

Commercial silicon dioxide nano-particles were modified by graft copolymerization macromolecular coupling agents (LMPB-g-MAH) of maleic anhydride (MAH) onto low-molecular-weight polybutadiene liquid rubber (LMPB) in dimethylbenzene. The hydroxyl groups on the surface of nano-SiO2 particles can interact with anhydride groups [–(CO)2–O–] of LMPB-g-MAH and an organic coating layer was formed. The covalent bands [–(CO)–O–,–(CO)–NH–] formed was testified by Fourier transform infrared spectra (FT-IR). Through transmission electron micrograph (TEM) observation, it was found that LMPB-g-MAH improved the dispersibility of nano-SiO2 particles in dimethylbenzene. By using the particle size analysis, it was confirmed that the optimum graft degree (GD%) and the optimum loading of LMPB-g-MAH is 9–11%, 10–12%, respectively. The dispersion stabilization of modified SiO2 nano-particles in dimethylbenzene was significantly improved due to the introduction of grafted polymers on the surface of nano-particles. Thermo gravimetric analysis (TGA) and contact angle measurement indicated that LMPB-g-MAH molecules were absorbed or anchored on the surface of nano-SiO2 particle and the using efficiency is 74.66%, which facilitated to hinder the aggregation of nano-SiO2 particles.

Variation of the Adhesive Properties of an Epoxy Resin Modified by End-Functionalized Liquid Polybutadiene as a Function of Temperature and Water Absorption

The adhesive behavior of a diglycidyl ether of bisphenol-A epoxy resin modified by end-functionalyzed liquid polybutadiene was evaluated as a function of the temperature and of the time of immersion in distilled water. The neat epoxy and three modified systems were analyzed. Butt joints and single-lap joints were tested using an API X60 steel as substrate. The monophasic system obtained by reacting the epoxy monomer with hydroxyl-terminated polybutadiene (HTPB) functionalyzed with isocyanate groups (EPI) showed the best performance. The results show that this system is stable in respect to water degradation, but changes when exposed to temperature. Under the set of experimental parameters of time and temperature used, however, the adhesive strength increased with the temperature. For all epoxy formulations analyzed the fracture mode observed was of the adhesive type.

Room temperature spontaneous exfoliation of organo-clay in liquid polybutadiene: Effect of polymer end-groups and the alkyl tail number of organic modifier

Disorderly exfoliated telechelic liquid polybutadiene/organo-clay nanocomposite gel was, for the first time, successfully prepared at room temperature of 26°C by simply compounding of carboxyl-terminated polybutadiene (CTPB) with organo-clay containing surfactant modifier with two alkyl tails. The dispersion behavior of organo-clay in liquid polybutadiene/organo-clay nanocomposite gels were systematically investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), rheology and compatibility experiments, focusing on the influence of the functional end-groups of the liquid rubber and the alkyl tails number of the organic modifier on the clay exfoliation. A unique liquid-like reversible rheological behavior was observed for CTPB/exfoliated clay nanocomposite gels with organic modifier having two alkyl tails, which is totally different with that of other samples (HTPB/C18-clay, HTPB/D18-clay and CTPB/C18-clay). And it is noteworthy that CTPB exhibits a higher level of dispersion with an organo-clay with two alkyl tailed surfactant than that with one alkyl tail.

Preparation and characterization of UV-cured epoxy nanocomposites based on o-montmorillonite modified with maleinized liquid polybutadienes

Polymeric nanocomposites based on an epoxy cycloaliphatic resin and o-montmorillonite (Cloisite 30B®) modified by reaction with maleinized liquid polybutadienes were prepared through photopolymerization. The conditions for the o-montmorillonite modification were settled. After the reaction, a strong increase of the basal spacing of the nanoclays was evidenced through XRD analysis. The modified clays were dispersed in the epoxy resin (5wt.%) and subjected to the UV-curing process. The kinetics of the photopolymerization process was evaluated by means of Real-Time FT-IR spectroscopy. The obtained nanocomposites were studied by means of XRD and TEM analyses; the formation of either intercalated or quasi-exfoliated structure was assessed. The thermal and mechanical properties of the cured films were evaluated and correlated to the morphology of the obtained nanocomposites.

Miniemulsion polymerization of styrene with liquid polybutadiene as the sole co-stabilizer

A low-molecular-weight liquid polybutadiene (LPB) is employed as the sole co-stabilizer in miniemulsion polymerization of styrene in present work. Results indicate that the LPB can be used as an effective co-stabilizer to retard the diffusional degradation of monomer droplets in miniemulsion system and get stable miniemulsions. When the miniemulsions were initiated, particle formation occurred predominantly by monomer droplet nucleation. Moreover, the effects of various reaction parameters on the polymerization kinetics and the nucleation mechanisms were also investigated. These parameters include the level of LPB ([LPB]) and the concentrations of SDS ([SDS]) and potassium persulfate ([KPS]). It is shown that the polymerization rate indicates little dependence on [LPB], while increases with increasing [SDS] and [KPS]. Competition between droplet nucleation and homogeneous nucleation occur in the course of polymerization, but droplet nucleation becomes more important by increasing [LPB] or decreasing [SDS]. Furthermore, the result that the particle size is rather insensitive to changes in [KPS] provides the most compelling evidence for the dominant droplet nucleation.