Some features of the heterophase emulsion graft polymerization of glycidyl methacrylate to polycaproamide fibre

Conclusions -- The special features of the graft polymerization of glycidyl methacrylate to polycaproamide fibre have been discovered. An anomalous effect of the copper compound and of hydrogen peroxide in the composition of the redox system on the rate of graft polymerization of glycidyl methacrylate has been found.-- The graft polymerization in the presence of the redox system Cu_c-H₂O₂ which has been examined is characterized by a high rate and high monomer conversion and takes place essentially without formation of homopolymer.-- The relationships which have been found indicate a high efficiency and an ecological cleanness of the graft polymerization process at hand.Moscow State Textile Academy. Translated from Khimicheskie Volokna, No. 5, pp. 14–16, September–October, 1992.     

Solution processing of composite fibers containing rodlike and thermoplastic polymers

The solution processing and mechanical properties made from blends of the rodlike polymer poly(p-phenylene benzobisthiazole) with either poly(ether ether ketone) or nylon 6,6 is described. The concentration dependence of the isotropic-nematic phase transition for solutions of these polymers in methane sulfonic acid is in qualitative agreement with a theory of Flory. The mechanical properties of fibers that were wet spun from isotropic solutions of poly(ether ether ketone) and poly(p-phenylene benzobisthiazole) are very sensitive to the concentration of the spinning solution. Fibers spun at concentrations near the isotropic-nematic phase boundary have poor mechanical properties, resulting from phase separation during coagulation. However, when the solution concentration is significantly below the critical value, stiff and strong fibers are produced. In contrast, when nylon 6,6 is used as the thermoplastic component, the mechanical properties are good and are insensitive to the solution concentration. We attribute the solution concentration effects to two factors. The first is the difference in the solubility of poly(ether ether ketone) and nylon 6,6 in methane sulfonic acid-water mixtures. The second is the connectivity of the nematic phase, which also depends on concentration and has a major impact on the mechanical properties of the resulting fiber.     

Simulation of heterophase polarization in polymers

Summary A computer simulation program for calculating the temperature and frequency dependent dielectric properties of twocomponent composites containing spherical inclusions is described. Both components may exhibit ohmic conduction and Debye-like dispersion besides the interfacial polarization. Assumptions used in the simulation are discussed and some peculiar features of the resulting spectra are demonstrated by numerical examples.From the International Seminar on Polymer Physics, High Tatra, CSSR, April 1982     

Some mechanical properties of particulate-filled thermosetting and thermoplastic polymers

A semiempirical, single-parameter equation describes the modulus of particulate systems This equation has been found applicable for thermoplastic/glass bead systems, and it is further verified for particulate thermosetting systems (epoxy and polyester matrices). The temperature effect on the modulus of epoxy/glass bead composites is also analyzed. Crazing characteristics calculated from tensile data of thermoplastic/glass bead composites are summarized and compared with literature results on the corresponding unfilled polymers. The effect of coupling agents and preliminary results on rigid foams are also presented.     

Some features of the process of strengthening fibres from fluorine-containing polymers

Conclusions An anomaly in mechanical properties in spinning F2M fluorinated copolymer has been detected.The reason for preference for using a multistage scheme for strengthening fluoropolymers has been analyzed.Translated from Khimicheskie Volokna, No. 1, pp. 31–32, January–February, 1990.     

Manganese(IV)-initiated graft polymerization of vinyl monomers on polyamide fibers

The feasibility of potassium permanganate to induce graft polymerization of vinyl monomers onto nylon 6 was investigated. The graft yield is greatly enhanced by increasing the monomer concentration, reaction time, and temperature. The addition of metallic ions as promoters to the grafting medium accelerates the graft polymerization. A mechanism for grafting was proposed. The activation energy of initiation E_i for methyl methacrylate was calculated and found to be 5 kcal/mole. The overall rate of graft polymerization R_p depends on the monomer concentration.     

Some features of pilling formation on carpeting from synthetic texturized new types of yarns

Conclusions It has been found that pilling formation does not take place on carpet items made from pneumotexturized polyamide or matrix-fibrillar yarns.On prolonged abrasion of carpet specimens from yarns of the matrix-fibril type, fibrillation of the yarns is observed, accompanied by an increase in the surface density of the carpet pile mass.Translated from Khimicheskie Volokna, No. 5, pp. 35–36, September–October, 1985.     

Graphene oxide modification with graft polymers via nitroxide mediated radical polymerization

We demonstrate a method to modify the surface of graphene oxide (GO) by grafting polymer chains using nitroxide mediated radical polymerization (NMRP). Surface modification by NMRP was achieved using GO functionalized with 2,2,6,6-tetramethyl-piperidine 1-oxyl (TEMPO, T) to produce graphene oxide-TEMPO (GO-T). GO prepared from graphite by the Hummer's method was facilely functionalized in one step with T. Graft polymerization reactions of styrene and isoprene were carried out using nitroxide chemistry to control the polymerization and the ‘grafting from the surface’ polymerization technique. GO-T acts as a multifunctional macroalkoxyamine initiating and controlling the polymerization in the presence of monomer. The grafting reactions were performed by dispersing GO-T in dimethylformamide and heating at 130 °C in the presence of monomer to form graphene oxide-g-polystyrene-TEMPO (GO-g-PS-T) and graphene oxide-g-polyisoprene-TEMPO (GO-g-PI-T). FT-IR, Raman, XPS, XRD, TGA and TEM data are consistent with the attachment of the TEMPO group to the GO surface and with polystyrene and polyisoprene being grafted onto the GO surface. The amount of PS and PI grafted to GO-T was estimated from TGA data to be approximately 34% for a 7 h reaction time and 68% for a 144 h reaction time, respectively.     

Preparation and characterization of thermoplastic polymers from hydroxyalkyl methacrylates

Soluble polymers have been produced from technical-grade 2-hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPHA) using a combination of vacuum distillation and solvent extractions to purify the monomers prior to solution polymerization. These extractions, particularly of HEMA with hexane and corn oil, were found to reduce the level of ethylene glycol dimethacrylate to < 1%, according to gas chromatographic analysis. Homopolymers of HEMA and HPMA and copolymers of HEMA with methyl methacrylate were prepared with a wide range of molecular weights and characterized by viscometry in dimethyl formamide, infrared spectroscopy including deuterium exchange experiments, and high resolution proton and carbon nuclear magnetic resonance (NMR) spectroscopy. The latter was used to determine copolymer composition and tacticity distribution.     

Ultrafine fibers electrospun from biodegradable polymers

Biodegradable poly(l‐lactide) (PLLA) and poly(ε‐caprolactone) (PCL) were electrospun into ultrafine fibers. The technological parameters influencing the spinning process and morphology of the fibers obtained were examined. These parameters included solvent composition, addition of certain organic salts, molecular weight and concentration of the polymers, capillary diameter, air ventilation, and pressure imposed on the surface of the solution as well as electrostatic field. By properly choosing and adjusting these parameters, submicron PLLA and PCL fibers with a narrow diameter distribution were prepared. Scanning electronic microscopy was used to observe the morphology and diameter size of the fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1085–1092, 2003     

High performance fibers from aromatic polymers

Examples are given to show how molecular structures may be synthesized to prepare polymers useful for the formation of fibers intended for specific end uses, particularly for high performance applications. Current trends and developments taken from the literature are reviewed and some new work from the laboratories of Monsanto Company is presented concerning the use of aromatic polymers for heat and flame resistant fibers. Some new polymers and new routes of synthesis are described. Correlations are made between flame resistance as measured by oxygen index (O.I.) values and the structure of a large number of aromatic polymers.     

Cationic graft polymerization of polymers from carbon fiber initiated by acylium perchlorate groups introduced onto the surface

The cationic graft polymerization of several monomers initiated by acylium perchlorate groups introduced onto the carbon fiber surface was investigated to modify the surface. The introduction of acylium perchlorate groups was successfully achieved by the reaction of silver perchlorate with acyl chloride groups, which were introduced by the reaction of surface carboxyl groups with thionyl chloride. It was found that the cationic polymerization of styrene is initiated by acylium perchlorate groups on the carbon fiber. In the polymerization, polystyrene was grafted onto the carbon fiber surface through the propagation of polystyrene from the surface. Ungrafted polymer was also formed by the chain transfer reaction of growing polymer cation to the monomer. The acylium perchlorate groups have the ability to initiate cationic ring-opening polymerization of tetrahydrofuran (THF) and ε-caprolactone (CL), polyTHF and polyCL being grafted onto the carbon fiber surface, respectively. Polyacetals, such as poly(1,3-dioxolane) and polyoxymethylene, were able to graft onto the carbon fiber by cationic ring-opening polymerization of the corresponding monomers.     

Thermal properties of strained thermoplastic polymers

Injection moulded tensile bars of several amorphous and semi-crystalline thermoplastic polymers have been deformed uniaxially to a macroscopic strain of 40% so that they showed necked and unnecked regions. From both the necked and unnecked regions of the tensile bars the specific heat and the thermal expansion coefficient were measured. The specific heat of the necked regions decreases about 20% with respect to unstrained samples for semi-crystalline polymers at temperatures between 40°C and 60°C and for amorphous polymers at temperatures between 50°C and 70°C. The thermal expansion coefficient becomes negative at these temperatures. A smaller negative expansion coefficient is observed even in the unnecked region although nearly no change in specific heat can be observed. There is also an increase in the heat of fusion of the semi-crystalline specimens of the necked region. Strain rate dependent effects on specific heat and thermal expansion were not observed within the accuracy of thermal analysis.     

External lubrication of high-temperature thermoplastic polymers

External lubrication of high-temperature thermoplastic polymers was studied experimentally. It was found that the nature of the lubrication fluid has a pronounced effect upon the behavior of the contact. It is postulated that premature failure of PEEK-lubricated contacts is caused by the migration of linear carboxylic acids into the polymer matrix at elevated temperatures, thereby producing significant plasticization. A sequence of events leading to failure is given and some rationale for it provided. © 1993 John Wiley & Sons, Inc.     

Miscibility of polyethyloxazoline with thermoplastic polymers

Polyethyloxazoline (PEOx) blends with several other thermoplastic polymers were examined by differential scanning calorimetry (DSC) for miscibility. Styrene/acrylonitrile (SAN) copolymers having compositions in the range of about 20–40% acrylonitrile (AN) by weight were found to be miscible with PEOx whereas SANs outside this range were not. The polyhydroxyl ether of bisphenol A (Phenoxy) was also found to be miscible with PEOx. A vinylidene chloride copolymer (Saran) was found to be partially miscible with PEOx, whereas poly(methyl methacrylate) and polycarbonate were not miscible at all.     

Dispersivity of rubbers in thermoplastic polymers

The main factors influencing the dispersivity of rubbers (nitrile and ethylene–propylene) in nylon 6 (PA-6) and polypropylene (PP) are investigated. On the basis of an equation, describing the influence of interfacial tension and viscosity ratio of disperse and matrix phases on the average size of dispersed phase particles, analysis of dispergation process in researched blended systems has been conducted. The limits of applicability of a given equation were established. It was shown that the best dispersivity of rubbers in the PA matrix is observed in that case when the viscosity values of initial components of a blend are close to each other. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1563–1567, 1999     

Synthetic fibers and thermoplastic short‐fiber‐reinforced polymers: Properties and characterization

Among the synthetic fibers, glass fibers (GF) are most widely used in thermoplastic short‐fiber‐reinforced polymers (SFRP), as they offer good strength and stiffness, impact resistance, chemical resistance, and thermal stability at a low price. Carbon fibers (CF) are applied instead of GF, when highest stiffness is required. Other types of synthetic fibers like aramid (AF), basalt (BF), polyacrylonitrile (PAN‐F), polyethylene terephthalate (PET‐F), or polypropylene fibers (PP‐F) are rarely used in SFRP, although they offer some advantages compared with GF. The aim of this article is, to give an overview of various fiber types with regard to their mechanical properties, densities, and prices as well as the performance of their thermoplastic composites. The mechanical properties are presented as Ashby plots of tensile strength versus tensile modulus, both in absolute and specific (absolute value divided by density) values. This overview also focuses on modification of fiber/matrix interaction, as interfacial adhesion has a huge impact on composite performance. A summary of established methods for characterization of fibers, polymers, and composites completes this article. POLYM. COMPOS., 35:227–236, 2014. © 2013 Society of Plastics Engineers