Effect of calcium carbonate on the properties of noncuring sealants based on butyl rubber and thermoplastics

The effect of the content, dispersity, and surface polarity of calcium carbonate on the physicomechanical and rheological properties of filled noncuring hot melt sealant formulations based on butyl rubber and various thermoplastics was examined. In the formulations based on nonpolar polymers, the cohesion strength and viscosity increase with an increase in the content and dispersity of calcium carbonate, with the strongest reinforcing effect observed with hydrophobized grades of calcium carbonate. With an increase in the polarity of the polymer base, untreated natural carbonate (chalk) becomes more efficient.     

Dynamic mechanical properties of chlorinated butyl rubber blends

The binary blends are prepared by chlorinated butyl rubber (CIIR) and 3,9-bis[1,1-dimethyl-2{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2, 4, 8,10-tetraoxaspiro[5,5]-undecane (AO-80), which are investigated by dynamic mechanical analysis and thermal analysis. It is shown that CIIR/AO-80 blends clearly exhibit two kinds of relaxations, which are attributed to the relaxation of CIIR-rich matrix and AO-80-rich domains, respectively, and attenuated total reflection (ATR)-FTIR spectrum indicates that the existence of intermolecular hydrogen bonds between AO-80 and CIIR. When AO-80 is replaced by petroleum resins, only one loss peak appears, and the position of it is related to the softening point and the content of the petroleum resin. In order to regulate the damping property of CIIR/petroleum resin blend, the ternary blend of CIIR/petroleum resin/AO-80/is prepared and a second peak appears at higher temperature indicating that a good damping material is obtained.     

Sealing compositions based on butyl rubber modified by reactive oligomers

The possibility of production of hot melt type reactive sealants based on butyl rubber and silaneterminated urethane semipolymers was determined.     

Chemical modification of butyl rubber. II. Structure and properties of poly(ethylene oxide)-grafted butyl rubber

Poly(ethylene oxide)-grafted butyl rubbers (IIR-g-PEOs), which were synthesized from potassium salt of polyethylene glycol monomethyl ether (PEGM) and chlorinated butyl rubber, were found to behave like thermoplastic elastomers. The poly(ethylene oxide) (PEO) content of these amphiphilic polymers was ca. 10 wt %, and their PEO lengths were 750, 2000, and 5000, respectively. The grafted segments of PEO in butyl rubber (IIR) aggregated to form the PEO domains in IIR matrix. At constant PEO content, the longer the PEO segment length, the larger the size and the crystallinity of PEO domains became. This PEO domain worked as a cross-linking site and a reinforcing filler. The degree of swelling in water of IIR-g-PEO film that was prepared from PEGM-5000 was largest, but its emulsification ability was smallest among them. © 1995 John Wiley & Sons, Inc.     

Chemical modification of butyl rubber. I. Synthesis and properties of poly(ethylene oxide)-grafted butyl rubber

A new amphiphilic polymer, i.e., poly(ethylene oxide) (PEO)-grafted butyl rubber (IIR-g-PEO), was synthesized by chemical modification of chlorinated butyl rubber (CIIR). This synthesis was based on the reaction between chlorine in CIIR and potassium salt of polyethylene glycol monomethyl ether (PEGM). PEGM's with molecular weights of 750 and 2000 were used. The maximum grafting percent of the resulted copolymers after the purification was ca. 45%, regardless of the molecular weight of PEGM. The microphase separated structure was observed in the films of IIR-g-PEOs. IIR-g-PEO, whose PEO molecular weight was 2000 and whose PEO content was 23.8 wt %, swelled 3.1% in water, and it was six times larger than the swelling of CIIR. The hydrophilicity of grafted polymers depended on the molecular weight of PEO side chains and PEO content. Even when the PEO contents were same in the polymers which were grafted PEGM-750 and PEGM-2000, their swellings in organic solvents were not equal. It was due to the difference of the microphase-separated structures of the grafted polymers. IIR-g-PEO, whose PEO molecular weight was 750 and whose PEO content was 10.3 wt %, swelled 1.5% in water, but showed an excellent emulsifying ability, where an oil-in-water-type emulsion was formed. © 1993 John Wiley & Sons, Inc.     

Toluene diffusion in butyl rubber

The sorption isotherm and the polymer mass-fixed diffusion coefficients, D, for toluene in butyl rubber have been measured by the incremental sorption method to concentrations of 130%, corresponding to a solvent volume fraction of 0.578. The increase in D with concentration is strongly exponential to a concentration of 30% and then begins to level out. Since the nature of the dimensional change occurring in vapor sorption was not known, the values of D were converted to solvent self-diffusion coefficients, D₁, assuming both swelling in the thickness direction (1D) and isotropically (3D). The free volume (FV) theory of Fujita was fitted to the resulting D₁ with the zero concentration diffusion coefficient and the self-diffusion coefficient of toluene as limiting values leaving only a single arbitrary parameter. In this form the FV theory was able to describe the trend of the experimental D₁ for the 1D and 3D cases equally well. Values of D were back-calculated from the FV relations for the 1D and 3D cases for comparison with the experimental results and with the diffusion coefficient determined by immersion in toluene. These comparisons favor the assumption that swelling is isotropic. It appears that the simple free volume relation is capable of providing a satisfactory representation of the experimental data with only a single fitting parameter, although there are moderate quantitative discrepancies. © 1994 John Wiley & Sons, Inc.     

Influence type of natural rubber on properties of green biodegradable thermoplastic natural rubber based on poly(butylene succinate)

Green biodegradable thermoplastic natural rubber (GB‐TPNR) based on simple blend of natural rubber (NR) and poly(butylene succinate) (PBS) was prepared using three NR alternatives: unmodified NR and epoxidized NR with 25‐ or 50‐mol% epoxide (ie, ENR‐25 or ENR‐50). It was found that ENR‐50/PBS blend showed the best compatibility, which resulted in superior mechanical and thermal properties with the highest crystallinity of the PBS phase, on comparing with the ENR‐25/PBS and NR/PBS blends. This might be attributed to stronger chemical interactions between the epoxide groups in ENR‐50 and the polar functional groups in PBS, which were confirmed by Fourier transform infrared (FTIR). Furthermore, scanning electron microscopy (SEM), atomic force microscopy (AFM), and polarizing optical microscopy (POM) micrographs of ENR‐50/PBS blend revealed phase separation with finer‐grained cocontinuous structure than in ENR‐25/PBS and NR/PBS simple blends. Furthermore, the chemical interactions in ENR‐50/PBS blend enhanced the resistance to accelerated weathering.     

Ageing of butyl rubber against UV irradiation

The photodegradation and stabilisation of butyl rubber have been studied in air in the temperature range of 258 to 318 K using a monochromatic light of 366 nm with a constant intensity flux of 1·68×10⁻⁸ einstein s⁻¹ cm⁻² in the absence and presence of cuprous di-isopropyl dithiophosphate. Irradiations were carried out on films at 0, 2, 4, 6, 8, 10, 12 and 14 h. An investigation into the nature and molecular changes during the irradiation with ultra-violet light (366 nm) of butyl rubber has been conducted by light scattering technique. The quantum yields of the photolysis of the polymer have been determined using a potassium ferrioxalate actinometer. Light scattering data have been processed to yield the activation energies in the absence and presence of 0·1 wt. % stabiliser. The incorporation of 0·7 wt. % cuprous di-isopropyl dithiophosphate in the matrix of the rubber film exercises the maximum protective influence on the photolytic degradation of the rubber.     

High‐power ultrasonic treatment of butyl rubber gum: Structure and properties

The ultrasonic treatment of butyl rubber gum during extrusion with a grooved‐barrel ultrasonic reactor was carried out at a mean residence time of 3.6 s and at different ultrasonic amplitudes. Gel permeation chromatography, NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and dynamic and mechanical property measurements were performed. The changes in the structure, curing behavior, and physical properties of the gum were found to be highly dependent on the applied ultrasonic amplitude. In particular, the molecular weight of the treated gum decreased and the molecular weight distribution increased with the ultrasonic amplitude. The number of double bonds in the ultrasonically treated gum was less than that in the virgin gum. The dynamic properties of the ultrasonically treated gums also indicated the occurrence of degradation during the ultrasonic treatment. The tensile strength and modulus of the vulcanizates prepared from the treated gums were reduced in comparison with those of the virgin vulcanizate because of degradation. In contrast, the elongation at break was higher. However, no significant changes in the thermal stability between the virgin and treated gums and among the vulcanizates were observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 334–344, 2005     

Influence of nonrubber components on properties of unvulcanized natural rubber

Low‐protein natural rubber (LPNR) and acetone‐extracted natural rubber (AENR) were prepared in solid form by alkaline treatment and acetone extraction to remove proteins and lipids. The content of proteins and lipids along with gel content were characterized by Fourier‐transform infrared spectroscopy (FTIR) and size exclusion chromatography with multiangle light scattering (SEC‐MALS) analysis. It was found that natural rubber (NR) treatment by alkaline hydrolysis or acetone extraction decreased proteins or lipids along with gel content. Also, having less proteins and lipids changed the network structure from macroaggregates to microaggregates. This resulted in inferior plasticity and poor mechanical, rheological, and dynamic properties. Furthermore, decreased strain‐induced crystallization and storage hardening were confirmed by temperature scanning stress relaxation (TSSR), after removal of proteins and lipids. Therefore, protein and lipid contents together with gel content play essential roles in controlling various properties of unvulcanized NR.     

Adhesives and sealants based on sulfur

Examples of applications of adhesives and sealants based on sulfur as a main component are presented. Prospective applications of sulfur as a cheap and available raw material for adhesives are shown. The basic formulations of sulfuric adhesives and the approximate technology of their production and application are described.     

The influence of thixotropic additives on the properties of sealants based on oligoester urethane thiol

The influence of thixotropic additives on the viscosity and thixotropy of sealants based on oligoester urethane thiol was examined. It was found that the fumed A-175 silica aerosil is the most efficient as a thixotropic additive for the sealants based on oligoester urethane thiol. The introduction of glycols along with the aerosil or hydrated silicon dioxide makes it possible to vary widely the viscosity and thixotropy of the sealant compositions based on oligoester urethane thiol.     

Adhesives and sealants based on bitumen

The need to ensure environmental and fire safety and labor protection has led to a the creation of a wider range of water-containing adhesive materials and the scope of their applications, as well as to increase the strength of adhesive joints on their basis. The present paper reviews aqueous adhesives produced by the domestic industry.     

Enhancement of mechanical properties of natural rubber with maleic anhydride grafted liquid polybutadiene functionalized graphene oxide

An effective procedure has been developed to synthesize the functionalized graphene oxide grafted by maleic anhydride grafted liquid polybutadiene(MLPB-GO). Fourier transform spectroscopy and X-ray photoelectron spectroscopy indicate the successful functionalization of GO. The NR/MLPB-GO composites were then prepared by the co-coagulation process. The results show that the mechanical properties of NR/MLPB-GO composites are obviously superior to those of NR/GO composites and neat NR. Compared with neat NR, the tensile strength, modulus at 300% strain and tear strength of NR composite containing 2.12 phr MLPB-GO are significantly increased by 40.5%, 109.1% and 85.0%, respectively. Dynamic mechanical analysis results show that 84% increase in storage modulus and 2.9 K enhancement in the glass transition temperature of the composite have been achieved with the incorporation of 2.12 phr MLPB-GO into NR. The good dispersion of GO and the strong interface interaction in the composites are responsible for the unprecedented reinforcing efficiency of MLPB-GO towards NR.     

Surface properties of biospecific coatings based on polyelectrolyte complexes of maleic acid copolymers

The surface properties of PE with bilayer and multilayer coatings based on polyelectrolyte complexes of the biospecific modified N-vinylpyrrolidone-maleic acid copolymer with chitosan, amphiphilic chitosan, or albumin have been investigated by atomic force microscopy, multiple attenuated total reflection spectroscopy, X-ray photoelectron spectroscopy, and goniometry. The copolymer of N-vinylpyrrolidone and maleic acid contains affine ligands to plasminogen—fragments of α-amino-bonded lysine—and imparts thromboresistant properties to the surface being modified. The surface morphology and the size of particles of deposited intermediate layers of chitosan or albumin differ from those of the bilayer (multilayer) coatings containing an additional external layer of the biospecific copolymer. The deposition of the multilayer polymeric coatings promotes a more thorough coverage of the protected surface. Characteristic absorption bands that demonstrate the presence of the modifying polymers on the PE surface have been revealed; this fact is also confirmed by the X-ray photoelectron spectroscopy data on the atomic composition of the analyzed surface. A significant increase in the hydrophilicity of the modified surface is established by the contact angle technique.     

Influence of fluorine-containing lubricant on properties of NR/BR rubber

K95 experimental lubricant being a product of fluorine reaction with a blend of mutually soluble poly(fluorine alcohols) and poly(fluorine esters) with molecular weight 240-900 g/mol was studied as an additive for rubber compounds based on blend of NR and BR. It was thermally stable till 270-300 °C. For comparison, it was tested simultaneously with homogenizing agent, Struktol MS40. Lubricant K95 added in a quantity of 0.5 wt% reduced the viscosity of rubber compound; it also improved compound flow in the mold. Mechanical properties of cured rubber not decrease while resistance to abrasion and fatigue increased. K95 participated in forming strong physical junctions (lower molecular weight between junctions of thermally stable network) while Struktol MS40 reduced the networking degree of rubber. As a result, it acts a multifunctional additive for NR/BR rubber.     

Cationic graft copolymerization of styrene onto chlorinated butyl rubber

The graft copolymerization of styrene onto chlorinated butyl rubber (Cl-IIR) with stannic chloride as cationic catalyst was studied in cyclohexane, and the rate of polymerization, per cent grafting and grafting efficiency were obtained. Polymerization was carried out in a sealed tube. The product was precipitated in methanol and dried. The increase in weight of Cl-IIR used was regarded as styrene conversion, and the increase in weight after extraction by boiling acetone as the weight of grafted styrene. Grafting was confirmed by fractional dissolution and infrared spectra. The rate of polymerization of styrene was proportional to concentrations of styrene, Cl-IIR and SnCl₄. The per cent grafting increased with styrene and SnCl₄ concentration, but was constant with Cl-IIR concentration. It also increased with time and with halogen content in the polymer. The addition of a polar solvent such as nitrobenzene greatly promoted the grafting reaction and the per cent grafting was 200%.     

Bromination of butyl rubber with a sodium bromide-tert-butyl hypochlorite system

The kinetics of bromination of butyl rubber by a sodium bromide-tert-butyl hypochlorite system is studied. The orders of reaction with respect to reactants are determined, the empirical dependence of the reaction-rate constant on temperature is found, and the activation parameters of reaction are estimated. It is shown that the bromination of isoprenyl units of butyl rubber results in substitution products of a predominantly exomethylene structure that provides a high rate of rubber vulcanization by zinc oxide.     

Influence of the properties of the matrix polymer on the strain characteristics of dispersion-filled composites based on polyethylene and crumb rubber

Mechanical properties of highly filled composites based on polyethylene of various grades and crumb based on ethylene-propylene-diene rubber were studied. The influence of the crack resistance of the matrix polymer on the strain properties of rubber-reinforced plastics was considered. A scheme of failure of highly filled composites with the deformable filler was suggested.