Morphology Of Elastomers Research Articles

Studying the effects of the butadiene rubber and nitrile butadiene rubber ratio on the elastomers properties

In this study the influence of the content of SKD-B butadiene rubber and BNKS-18 AMN nitrile rubber in the blend on the properties of the resulting elastomers is investigated. The combination of frost-resistant and aggressive media resistant rubbers in the blend allows to adapt the properties of vulcanizates to the required operating conditions. The research revealed that the level of physical and mechanical properties, aggressive media resistance and frost resistance depend on the ratio of rubbers. The study of properties of elastomers revealed two glass transition temperatures and two thermal transitions at negative temperatures corresponding to nitrilebutadiene and butadiene rubbers. The phase morphology of elastomers, characteristic for butadiene nitrile or butadiene rubbers in dependence on their ratio in the blend, was investigated by electron microscopy. Based on the developed elastomer, dust covers for CV-joints were produced. They were tested in real operating conditions in the temperature range from –52 to 33°C.

AFM study of the morphology of elastomers based on polyurethanimides with various rigid and flexible fragments

The morphological characteristics of the surface of a number of films of elastomers based on polyurethanimides (PUI) were studied by atomic force microscopy (AFM). Significant differences in the surface morphology of PUI films were found depending on the composition: from granular morphology with different grain sizes or spongy morphology with nano - and submicron pores and cavities on the surface, to spherulitic morphology. It is shown that the roughness of the free surfaces formed during the films formation from the solution is significantly lower than the roughness of the surface which was in contact with the substrate. The influence of the chemical structure and size of the rigid diamine fragments in PUI macromolecules on the morphology of the film surface and the presence of different phases in the AFM torsion mode is established. The comparison of the deformation and strength characteristics showed high values of the elongation at break (more than 1400%) in the PUI films with a developed porous structure of both surfaces. The results obtained show the need to control and take into account the morphological parameters of the surface layers of products made of highly elastic imide-containing materials for their use for technical and other purposes. Keywords: synthesis of polyurethanimides, atomic-force microscopy, elastomer films morphology, surface roughness, viscosity and strain-strength characteristics.

Effect on the Impact Properties of Adding Long‐Chain Branched Polypropylene in Polypropylene‐Polyolefin Elastomer Cellular Polymers Produced by Core‐Back Injection Molding

AbstractDifferent blends of a linear polypropylene (L‐PP), a long‐chain branched polypropylene (LCB‐PP), and a polyolefin elastomer (POE) are prepared and foamed using core‐back injection molding. The objective is to analyze the use of POE and LCB‐PP as complementary strategies to improve cellular polymers’ impact response. Different parameters are then studied in blends and injection molded plaques to understand the samples’ mechanical behavior. Parameters such as the interfacial tension, elastomer morphology, extensional rheology, cellular structure, and crystallization behavior are characterized in detail. The addition of POE allows improving the impact response of both the solids and cellular polymers, but the stiffness is reduced. On the other hand, the substitution of L‐PP by LCB‐PP, in blends containing POE, results in solids and cellular materials with both better stiffness and better impact properties, due to the different crystalline morphology comprising the samples, a different cellular orientation, and thicker solid skin.

Liquid Crystal Elastomer Microspheres as Three-Dimensional Cell Scaffolds Supporting the Attachment and Proliferation of Myoblasts

We report that liquid crystal elastomers (LCEs), often portrayed as artificial muscles, serve as scaffolds for skeletal muscle cell. A simultaneous microemulsion photopolymerization and cross-linking results in nematic LCE microspheres 10-30 μm in diameter that when conjoined form a LCE construct that serves as the first proof-of-concept for responsive LCE muscle cell scaffolds. Confocal microscopy experiments clearly established that LCEs with a globular, porous morphology permit both attachment and proliferation of C2C12 myoblasts, while the nonporous elastomer morphology, prepared in the absence of a microemulsion, does not. In addition, cytotoxicity and proliferation assays confirm that the liquid crystal elastomer materials are biocompatible promoting cellular proliferation without any inherent cytotoxicity.

Comparison of the toughening behavior for poly(ethylene terephthalate) with spherulitic or ellipsoid elastomer-particles

Melt blending thermoplastic polymers with various elastomers have been considered as the most economical and effective route to toughen these polymers. Yet, the underlying mechanisms controlling such toughening are controversial. We demonstrate here that differences in elastomer morphology can induce dramatically changes in toughening efficiency. In this study, the brittle poly(ethylene terephthalate) (PET) was toughened by poly(ethylene-octene) (POE) elastomer with maleic anhydride grafted POE (mPOE) as compatibilizer. Depending on the shearing action from the nozzle during injection molding, special sample with elongated elastomer particle but almost isotropic and amorphous PET matrix was prepared by injection molding. The toughening efficiency for elongated or spherical elastomer particles, therefore, could be evaluated without the influence of matrix resin. Most interestingly, compared to spherical elastomer particle, the occurrence of brittle-ductile transition (BDT) of the elongated-elastomer-toughened PET was delayed. SEM micrographs of the impact fracture surface suggested that the matrix shear yielding could not be effectively initiated in the oriented blends until the elastomer content increased up to 40 wt.%.

Filler Distribution and Domain Size of Elastomer Compounds by Solid-State NMR and AFM

Abstract Solid-state NMR methods were used to characterize the filler distribution in rubber blends and domain size of thermoplastic vulcanizates (TPV). Correlation between filler content and magic angle spinning (MAS) 13C and 1H NMR signal linewidth was established, and filler content in each component of the rubber blends was determined. In IIR/BR and BIMS/BR blends, carbon black enriches in BR phase. Comparison of the carbon black enrichment in both blends suggests that BIMS has a slightly stronger interaction with fillers than does IIR. Results obtained from AFM analysis were compared with NMR observations. Spin diffusion NMR was demonstrated to be useful for quantifying the amount of interfacial component in TPV. Its advantages — ease of quantification and high sensitivity for smaller domains — make it a complementary approach to microscopic techniques for elastomer morphology characterization.

Biodegradable aliphatic thermoplastic polyurethane based on poly(ε‐caprolactone) and L‐lysine diisocyanate

AbstractA biodegradable aliphatic thermoplastic polyurethane based on L‐lysine diisocyanate and 1,4‐butanediol hard block segments, and 2000 g/mol poly(ε‐caprolactone) diol soft block segments was synthesized. The resulting polymer was a tough thermoplastic with ultimate tensile strength of 33 MPa and elongation of 1000%. The polymer displayed classic segmented thermoplastic elastomer morphology with distinct hard block and soft block phases. Thermal and dynamic mechanical analyses determined that the material has a useful service temperature range of around −40 °C to +40 °C, making it an excellent candidate for low‐temperature elastomer and film applications, and potentially as a material for use in temporary orthopedic implant devices. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2990–3000, 2006

Deep etching of biocompatible silicone rubber

Fluorine-based reactive ion etching of commercial biocompatible silicone rubber based on poly(methylhydrogensiloxane-co-dimethylsiloxane) has been studied. The basic aim was to investigate the etch rates and the etch profiles obtained under various plasma conditions. The effect of process pressure on the polysiloxane morphology was also examined. Polysiloxane layers supported on the standard silicon wafers were etched using SF 6 + O 2 or CF 4 + O 2 plasmas. The etch rate of the polymer in a SF 6 + O 2 plasma (over 1 μm/min) was found to be higher than that in a CF 4 + O 2. The advantageous effect of a higher pressure on the etch rate was revealed. The etch rate enhancement with pressure was more pronounced in an SF 6 + O 2 plasma than in an CF 4 + O 2 plasma. Significant changes in elastomer morphology were found after the plasma treatment and their dependence on plasma conditions was described.

Image Analysis of Elastomer Morphology in Toughened Thermoplastic and Thermoset Resins

A thermoplastic polystyrene-based material with styrene-butadiene-styrene dispersed particles and a thermoset polyester toughened with butadiene-acrylonitrile particles were studied. Photomicrographs of materials that had different proportions of elastomer were processed and the images analysed. The changes in the morphological characteristics were correlated with the fracture toughness and modulus of elasticity.

Mechanical Properties and Deformation Behavior of the Double Gyroid Phase in Unoriented Thermoplastic Elastomers

The mechanical properties of the double gyroid (DG) cubic phase in glassy−rubbery block copolymer systems are examined. The stress−strain properties of an isoprene-rich polystyrene/polyisoprene/polystyrene (SIS) triblock and a polystyrene/polyisoprene (SI) starblock DG, both comprised of two separate interpenetrating glassy networks embedded in rubbery matrices, are compared to those of the sphere, cylinder, and lamellar morphologies. This 3-dimensionally interpenetrating periodic nanocomposite is found to have superior properties over those of its classical counterparts, attributable to the morphology rather than to the volume fraction of the glassy component, the architecture of the molecule, or the molecular weight. The DG is the only polygranular/isotropic thermoplastic elastomer morphology which exhibits necking and drawing and which requires considerably higher stresses for deformation up to 200% strain than any of the three classical microdomain morphologies. The deformation behavior of the DG is f...

Effect of formulation on properties and morphology of polyurethane elastomers

AbstractA model polyurethane elastomers system has been used to study the relationships between chemical formulation, polymer physical structure and mechanical properties. The elastomers were made from formulations comprising a polyether polyol blend (diol plus triol), a chain extender blend (1,4 butane diol plus 1,1,1‐trimethylol propane) and 4,4′‐di‐isocyanate diphenylmethane. The morphologies of the elastomers were investigated in detail, mainly by means of small angle X‐ray scattering techniques. It was confirmed that the polyurethane systems examined comprised domains 50 to 100 Å in size and spaced around 100 to 200 Å apart. A complete decription of the polyurethane morphology has been made in terms of the volume fraction of domains present, the average domain size and the average domain–domain separation. The results suggest that, whilst it is possible to correlate, in general, formulation changes with variations in the elastomer morphology, it seems that direct correlations between physical structure and mechanical properties are not very meaningful in the present model system. However, it is clear that knowledge of the morphology is of considerable importance in interpreting the effects of formulation on observed properties.

Method for study of the morphology of elastomers crystallized in bulk at low temperatures

Method for study of the morphology of elastomers crystallized in bulk at low temperatures