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Abstract This study investigated novel methods for treating the surface of nitrilebutadiene rubber to enhance its stability and resistance to thermal oxidation and aggressive media. The rubber surface was modified [...]

Abstract A series of polyethylene terephthalate-polyethylene naphthalate (PETN) copolymer films with excellent oxygen barrier properties were prepared by introducing trace amounts of hydroxy-terminated polybutadiene (HTPB) into PETN via in-situ polymerization. [...]

Cure kinetics of modified epoxy resins cured with dicyandiamide are studied. The influence of different heating rates in the curing process, such as curing behavior, morphology, and thermo-mechanical properties, is studied. Additionally, three different post-cure cycles at 180[degrees]C are employed. Two butadiene-based toughening agents are used, a carboxyl-terminated polybutadiene-co-acrylonitril (CTBN) prepolymer and a functionalized block copolymer of polytetrahydrofuran and hydroxyl-terminated polybutadiene. The amphiphilic block copolymer enables investigations with a bimodal particle size morphology. All results are contrasted with those of the neat resin and butadiene-free block polymer. Faster curing processes result in smaller average particle sizes and better fracture toughness of the modified epoxy resins. Further improvements are achieved with additional postcure cycles at 180[degrees]C. An increased interfacial adhesion between the particles and the epoxy matrix is considered to be the main mechanism. Optimized lengths of the post-cure process can be determined with the butadiene-based toughening agents indicating a competing thermal degradation. Longer post-cures than 40 min lead to lower fracture toughness in the butadiene-based modified materials. In general, similar influences of the curing and post-curing process on the bimodal and unimodal distributed system can be observed differing in more intense dependencies of the bimodal system. KEYWORDS curing of polymers, morphology, particle size distribution, structure-property relations, thermosets, 1 | INTRODUCTION Toughened thermoset materials based on cross-linked epoxy resins are used extensively as structural adhesives, matrix of composites, coatings, or potting compounds. [1-4] The two general, fundamentally different [...]

Acrylonitrile-butadiene-styrene (ABS) is an extensively utilized rubber-toughened amorphous thermoplastic in industry. Compared to other amorphous thermoplastics, the most promising mechanical quantity of ABS is its high impact resistance. Thus, understanding the mechanical response of ABS to multiaxial loads is of the great industrial concern. The primary objective of this study was to characterize the flexural response of ABS by conducting three-point bending tests at two distinct deformation rates of 5 and 10 mm/s to figure out the deformation rate effect on the flexural response of ABS. It was observed that the ABS act stiffer with an increased deformation rate. Numerical implementation of three-point bending tests for each deformation rate was performed using the semi-analytical material model (SAMP-1) available in LsDyna finite element code. The simulations for each deformation rate were run depending on SAMP-1 and Von-Misses yield surface formulations to figure out the effect of nonidentical material behavior of ABS in tension, compression, and shear on flexural response. The percentage error in the predicted peak force values considering the compression and shear test data (SAMP-1) and without it (Von Misses) was 3% and 7% for deformation rate of 5 mm/s and 5% and 12% for deformation rate of 10 mm/s. Hence, predicting the flexural behavior of ABS accurately, dissimilar material behavior needs to be taken into consideration. Moreover, associated and nonassociated flow rule effects on the flexural response of ABS were numerically investigated and there was no significant influence observed on the flexural response of ABS. KEYWORDS acrylonitrile-butadiene-styrene, amorphous, flexural behavior, SAMP-1, thermoplastic, 1 | INTRODUCTION Amorphous polymers have been widely utilized as loadcarrying components in numerous fields, such as automotive, medical, and electronics, since they offer many distinguished mechanical quantities including high [...]

Fused filament fabrication (FFF) is a process where thermoplastic materials are heated to its melting point and then extruded, layer by layer, to create a three dimensional printed part. Printing occurs in a layered manner, which leads to creation of voids (air gaps) in the 3D printed parts. These voids act as centers for crack initiation, propagation and therefore resulting bulk mechanical properties are lower. This paper focuses on microstructural characterization and analysis of fused filament fabricated tensile test coupons made from acrylonitrile butadiene styrene polymer, at various design conditions. Comparable tensile modulus with injection molded specimens was obtained for FFF design condition that is, slice height (0.1778 mm), raster width (0.4064 mm), raster to raster air gap (-0.0015 mm), contour to raster air gap (-0.0508 mm) and raster angle (0[degrees]). Scanning electron microscope studies provided an understanding as to why FFF processed specimens yielded lower failure strain and an insight into the presence of intralayer voids in specimens having lower tensile modulus. The study confirmed that though bulk mechanicals were affected by the combined effect of inter, intra and interfacial voids, intravoids had a predominant influence. KEYWORDS 3D printing, acrylonitrile butadiene styrene, additive manufacturing, air gaps, fused filament fabrication, injection molding, SEM, tensile, voids, 1 | INTRODUCTION Technologies to process and form plastic parts have changed and evolved over time. Even though conventional injection and compression molding are widespread processing techniques, the trend in [...]

The control of polymerization conditions and final properties of polybutadiene produced through solution polymerizations constitute an important industrial challenge, which can be tackled with help of mathematical models. For this reason, the present work focus on the development of a phenomenological mathematical model, and estimation of the respective model parameters, in order to describe the kinetics of 1,3-butadiene solution polymerizations catalyzed by neodymium versatate. The proposed model can be used to predict some important final properties of polybutadiene resins, including the cis-content and average molecular weights, and the evolution of operation conditions that are used at plant site to monitor the course of the reaction, including the reaction temperature and pressure. Given the low required computation times, the proposed model can be used for purposes of monitoring and control in actual industrial sites., INTRODUCTION The synthetic rubber industry has been developing and investing in the manufacture of new elastomers and vulcanized compounds. For this reason, the production of high cispoly-butadiene has been the [...]

The present study focuses on the terpolymer of styrene (St), isoprene (Ip), and butadiene (Bd) synthesized together in cyclohexane at 70°C with neodymium (Nd) compound, alkylaluminum, and chlorinating agent (Cl) rare earth cocatalyst system. The resultants possessed atactic St-St sequences and high cis-1,4 polyconjugated olefins in macromolecular chains besides controllable composition. The composition of the St-Ip-Bd terpolymers and molecular weight ([M.sub.w]), molecular weight distribution ([M.sub.w]/[M.sub.n]) were controlled through the adjustment of Nd compound, alkylalumium, monomers feed ratio (St/Ip/Bd), and [Nd]/[monomers]. With the inventory rating of St raised from 15% to 55%, the content of St in the terpolymers got increased from 2% to 15%. And the content of the Ip segments and Bd segments in the terpolymers increased from 33% to 56% and from 28% to 54%, respectively, with the proportion of Ip/Bd varied from 1/2 to 2/1. As the [Nd]/[monomers] varied from 1.0 x [10.sup.-3] to 5.0 x [10.sup.-4], the molecular weight increased from 1.3 x [10.sup.4] to 2.7 x [10.sup.4]. According to the proton nuclear magnetic resonance (1H-NMR) and 13C-NMR, it was proved that both microstructures of polybutadiene segments and polyisoprene segments were high cis-1,4-configuration. A single glass-transition temperature was observed in the differential scanning calorimetry curve., INTRODUCTION Taking a world view of the current research in the field of synthetic rubber industry, one may easily find out that poly(conjugated-olefin) rubbers played an essential role in the [...]