Thermal behavior and morphological properties of novel magnesium salt–polyacrylamide composite polymers

Magnesium salt–polyacrylamide composite polymers have been prepared by blending magnesium chloride and magnesium hydroxide, respectively, with polyacrylamide aqueous solution. The thermal behavior of the dried magnesium salt–polyacrylamide composite polymers has been studied. Differential scanning calorimetric (DSC) analysis and thermal gravimetric analysis (TGA) were carried out to investigate the changes of the composite polymers' behavior with temperature. The kinetics of the thermal decomposition of magnesium salt–polyacrylamide composite polymers was investigated over temperature range of 35–800°C with three heating rates of 10, 20, and 40°C/min under nitrogen atmosphere. Flynn and Wall's model was usedto determine the activation energies of thermal decomposition for magnesium salt–polyacrylamide composite polymers. The activation energies needed to decompose 50 wt% of magnesium hydroxide‐polyacrylamide (MHPAM) composite polymer ranged from of 28.993–174.307 kJ/mol which are higher than the values for magnesium chloride–polyacrylamide (MCPAM) composite polymer (21.069–39.412 kJ/mol). Therefore, MHPAM composite polymer has a better thermal stability compared with MCPAM composite polymer. The morphological properties of magnesium salt–polyacrylamide composite polymers were studied using scanning electron microscopy (SEM). Energy‐dispersive X‐ray (EDX) spectroscopy was used to determine the composition of the chemical elements. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

A review on oil palm empty fruit bunch fiber‐reinforced polymer composite materials

Natural fiber‐reinforced polymer composite materials have emerged in a wide spectrum of area of the polymer science. The composite produced from these types of materials are low density, low cost, comparable specific properties, and most importantly they are environmental friendly. The composite materials produced from oil palm fibers and commercially available polymers have offered some specific properties that can be comparable to conventional synthetic fiber composite materials. However, these properties are greatly dependent on the compatibility of oil palm fibers and matrix phase with moisture absorption as one of the critical issues that becomes the drawbacks of the oil palm fiber polymer composite materials. Apparently, it greatly affects the physical as well as mechanical properties of the composite materials. The present review reports the work on oil palm empty fruit bunch (OPEFB) fiber‐reinforced polymer composites with some interest on the OPEFB physical structure, and chemical compositions. Finally, the incorporation of OPEFB into polymeric materials leads to several interesting consequences on the water absorption characteristics and the mechanical properties, which have been reviewed. POLYM. COMPOS., 31:2079–2101, 2010. © 2010 Society of Plastics Engineers     

Urethane/acrylic composite polymer emulsions

Blends of waterborne urethane and acrylic polymer systems were studied to obtain a composite emulsion that would have all of the advantages of the two polymers without their associated disadvantages. An approach to achieve extensive polymer-polymer interactions through crosslinking reactions was studied to optimize the positive aspects of each polymer. The crosslink system used an acrylic polymer emulsion containing keto or aldo groups and a polyurethane dispersion incorporating a hydrazine group. The degree of crosslinking was determined by FT-IR Single package, ambient temperature crosslinking emulsions were obtained by using this system. In addition to the excellent properties these two polymers normally possess, the crosslinked blends exhibit synergistic effects in film properties, such as good solvent resistance and low heat sensitivity over a wide range. Composite polymers of this type could be useful in applications where high durability is required: tennis court coatings, floor coatings, laminating adhesives. and paper and textile finishes.     

Measurement of the rheological properties of polymer melts with slit rheometer. III. Two-phase systems—high-impact polystyrene and ABS resin

Measurements were made of the rheological properties of commercially available rubber-reinforced two-phase polymer systems. The polymers chosen for study were two high-impact polystyrenes (Union Carbide Corp., TGDB9500 and TGDB2100) and an acrylonitrile–butadiene–styrene (ABS) resin (Monsanto Co., Lustran I240 Natural). For the study, a slit rheometer was used, which was described in part I of this series. The present paper, the third of this series, clearly demonstrates the usefulness of the slit rheometer for characterizing polymer systems of industrial importance by means of their viscous and elastic properties in the molten state.     

Modification of Cellulose Acetate by Aliphatic Isocyanates for Reverse Osmosis Studies

Abstract

In the present study an emphasis has been given to modify the commercially available cellulose acetate (CA) (39.9% acetyl) by aliphatic isocyanates to increase the mechanical resistance of the polymer. The transport properties of the cast membranes from these modified CA polymers have been studied. The work has been further extended to study the thermo oxidative degradation of these modified cellulose acetate polymers in dry state in air.     

Supported single‐site catalysts for slurry and gas‐phase olefin polymerisation

Early and late transition metal single‐site catalysts revolutionised the polyolefin manufacturing industry and research with their ability to make polymers with uniform microstructural properties. Several of these catalysts are currently used commercially to produce commodity and differentiated‐commodity resins. The key to their rapid success and industrial implementation resided in the fact that they could be used without major modifications in the polymerisation reactors that previously used heterogeneous Ziegler–Natta and Phillips catalysts. Since most of these industrial processes use slurry or gas‐phase reactors, the soluble single‐site catalysts must be supported on adequate carriers that ensure not only high activity, but also the formation of polymer particles with the proper morphology and bulk densities. In this article, we will review several methods used for supporting single‐site early and late transition metal catalysts on a variety of supports. © 2011 Canadian Society for Chemical Engineering     

Synthesis,chemical resistance,and water absorption of bamboo fiber reinforced epoxy composites

Natural fiber reinforced polymer composites are being increasingly used in the civil infrastructure. They have tremendous applicability to bridge systems ranging from use in seismic retrofit and strengthening of existing structural components, either in all composite form, or in conjunction with conventional construction materials. Natural fibers are not only strong and lightweight but also relatively inexpensive. Among the various natural fibers, bamboo finds widespread use in housing construction around the world, and is considered as a promising housing material. In this article, bamboo fiber reinforced epoxy composite has been synthesized by hand lay up technique. Effect of fiber content on chemical resistance and water absorption of composites has been studied to find the industrial suitability of the composites. Scanning electron micrographs of composites were used for a qualitative evaluation of the interfacial properties of bamboo/epoxy composites. These results indicate that bamboo can be used as a potential reinforcing material for making low load bearing thermoplastic composites. POLYM. COMPOS., 141–145, 2016. © 2014 Society of Plastics Engineers     

Synthesis of magnesium aluminate spinel—An overview

Magnesium aluminate spinel (MAS) is a remarkable ceramic material known for its unique combination of beneficial properties. But due to volume expansion associated with spinel formation, and the high cost of production, MAS was not commercially successful till last century. However, environmental friendliness and superior properties have helped MAS to substitute magnesia-chrome refractories and are commercially acceptable with time. From an industrial perspective, solid-oxide reaction route or conventional oxide mixing route is the most popular method used for the synthesis of MAS. Although there have been myriad other common routes-coprecipitation, sol–gel, auto-ignition, molten technique, and so forth to produce spinel, solid-oxide reaction route is still the principal route from the industrial point of view owing to its ease of bulk production and low cost of production for refractory applications. This report attempts to accumulate the information on different synthesis techniques used for the synthesis of MAS for easy and ready reckoning.     

Fabrication and Properties of Modified Poly(butylene terephthalate) with Two-Step Chain Extension

High-viscosity, low-crosslinked poly(butylene terephthalate) (PBT) from organic chain extenders and inorganic particles are prepared. PBT modification adopted from multifunctional, commercially available chain extension containing nine epoxy groups (ADR9) occurs in the first-step chain extension; hydroxyl addition modified dioxazoline (BOZ) serves as the second step. Anion stratiform inorganic hydrotalcite (HT) is used to adjust the crystallization behavior and damp-heat aging properties of PBT. The reaction between the chain extender and PBT end-groups such as carboxyl (–COOH) and hydroxyl (–OH) enhances the interfacial bonding between the PBT matrix and dispersed HT phases. With a fraction of chain extenders in the PBT matrix, the chain-extended PBT exhibits higher mechanical properties, intrinsic viscosity, average molecular weight, and melt viscosity than those of unmodified PBT. Damp-heat aging resistance measurements show correlation with initial carboxyl content in the resin. Reducing the concentration of carboxyl end-groups in the resin is shown to increase hydrolytic stability. The modified PBT resin can be used in optical fiber communication cable industry for its high level of damp-heat aging resistance as well as good mechanic properties.     

Interfaces in repair,recycling, joining and manufacturing of polymers and polymer composites

A basic set of 10 thermoset polymer–polymer interfaces has been identified to play a vital role in the technical and economic aspects of composite manufacturing (RIM/RTM, compression molding, autoclave lamination), recycling, repair, welding, and joining of polymer composites. Knowledge of the chemical interactions and molecular connectivity at these interfaces and their influence on processability and mechanical properties of the polymers and polymer composite is essential, and has been the focus of this research. Presented in this report are the results of an exploratory study performed to understand the interactions at the polymer–polymer interface and their influence on the interfacial fracture toughness of a thermoset vinyl ester, which is widely used in liquid molding applications. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 775–785, 1999     

Use of MALDI-ToF MS to elucidate the structure of oligomeric impurities formed during ‘click’ cyclization of polystyrene

Polymers with a cyclic topology exhibit a range of unique and potentially useful physical properties, including reduced rates of degradation and increased rates of diffusion in bulk relative to linear analogs. However, the synthesis of high purity cyclic polymers and verification of their structural purity remain challenging. The copper-catalyzed azide–alkyne “click” cyclization route toward cyclic polymers has been widely used, due to its synthetic ease and its compatibility with diverse polymer backbones. Yet unoptimized click cyclization conditions have been observed to generate oligomeric byproducts. In order to optimize these cyclization conditions, and to better understand the structure of the higher molecular weight oligomers, these impurities have been isolated and characterized. Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI–ToF) MS is a particularly valuable characterization tool and was used to determine that the high molecular weight impurities are predominantly cyclic oligomers. It should also be noted that the rapid analysis and small analyte requirements of this MS technique make it particularly attractive as a general tool for elucidating polymer architecture.     

Effectiveness of Polystyrene/Carbon Nanotube Composite in Electromagnetic Interference Shielding Materials: A Review

Polystyrene is an efficient thermoplastic having fine processability, chemical inertness, and mechanical performance. Technological advances have led to several industrial appliances of polystyrene-based materials ranging from insulation to electromagnetic interference shielding. In this state-of-the-art review, primarily structure and properties of carbon nanotube and polymer/carbon nanotube composite have been discussed. Carbon nanotube is considered as a brilliant filler for polymers. Therefore, a comprehensive discussion regarding high-performance polystyrene/carbon nanotube composite is presented. Main focus of review is the significance of electromagnetic interference shielding phenomenon in polystyrene/carbon nanotube composite. Owing to advantageous properties, these composite have potential to replace traditional shielding materials.     

Resistance of the Polypyrrole/Polyimide Composite by Electrochemical Impedance Spectroscopy

Electrically conducting polymers are promising for applications in polymer based charge storage devices and for membrane applications. Composing polypyrrole with polyimide improves mechanical properties of polypyrrole and affects the electrochemical properties of the composite. In this paper resistance to ion flow of pure polyimide and of the polypyrrole/polyimide composite were studied by electrochemical impedance spectroscopy, comparatively, as a function of applied potentials and of amount of polypyrrole. Electron scanning microscopy and surface mapping were used for surface characterization. Observed behavior was explained with electroactivity of the components of the composite. Conclusions about the effect of polypyrrole on the structure and resistance were made.     

纳米碳管及其在聚合物中的应用

综述了聚合物基纳米碳管复合材料的制备方法及增强型、耐热型、抗静电型和电磁屏蔽型纳米碳管/聚合物复合材料的性能和应用。纳米碳管作为填料加入到聚合物中，可改善聚合物的机械性能和耐热性能，也可赋予聚合物抗静电和电磁屏蔽等新性能。随着对纳米碳管研究的不断深入，其将在物理学、化学、材料学领域尤其在纳米电子器件和复合材料领域有很大的突破。     

The dynamic mechanical analysis of epoxy–copper powder composites using azole compounds as coupling agents

The dynamic mechanical properties of cured epoxy resin have been studied in which copper powder treated or untreated with azole compounds was used as fillers. The untreated fillers do not shift the glass transition temperature of the matrix polymer of the composites, whereas the storage modulus rises with increasing content of fillers. The application of azole compounds as coupling agents, which could react with both copper and epoxy resin, extended the polymer–filler interactions. The composite filled with copper powder treated with benzotriazole shows a strong reinforcement effect and high resistance to moisture.     

Condensation polymers from natural oils

Innovative technologies and competitive industrial products are reducing the dependence on petrochemicals for the production of polymers. Increasing concerns about the deteriorating environment caused by conventional polymers have directed worldwide research toward renewable resources. Vegetable oils are one of the most readily available alternative renewable resources. The functional groups present in natural oils can be activated for condensation polymerization. Accordingly, various types of useful condensation polymers, such as polyurethanes, polyesters and polyethers, are being produced by this route. The incorporation of natural oils into the polymer chain allows tailoring the properties of polyurethane products, for their widespread applications.     

Polyethylene composite fibers. I. Composite fibers of high‐density polyethylene

Polymer matrix composites are generally studied in the form of bulk solids, and very few works have examined composite fibers. The research described here extended such bulk studies to fibers. The question is whether or not what has been reported for bulk polymers will be the same in fibers. In this article are reported studies of high‐density polyethylene (HDPE), whereas those of linear low‐density polyethylene are reported in part II of this article series. Two types of filler were used, that is, organically modified montmorillonite (OMMT), in which the nanosized filler particles had a high aspect ratio, and microsized calcium carbonate (CaCO₃), with an aspect ratio nearer to unity. Composite fibers of both as‐spun and highly drawn forms were prepared, and their structures, morphology, and mechanical properties were studied. It was found that the microsized particles gave HDPE composite fibers with mechanical properties that were the same as those of the neat polymer. In the case of clay composite fibers, the clay interfered with the yield process, and the usual yield point could not be observed. The particle shape did not affect the mechanical properties. The fibers showed different deformation morphologies at low draw ratios. The CaCO₃ composite fibers showed cavities, which were indicative of low interaction between the polymer and the filler. The OMMT composite fibers showed platelets aligned along the fibers and good polymer–filler interaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

An inelastic electron tunnelling spectroscopy (IETS) study of poly(vinylacetate) poly(methyl methacrylate) and poly(vinylalcohol) adsorbed on aluminium oxide

IETS is used to investigate the adsorption of poly(vinylacetate) (PVA), poly(methylmethacrylate) (PMMA), and poly(vinylalcohol) (PVOH) on aluminium oxide. These polymers are of interest in the field of adhesion science, and until now synthetic macromolecules have not been studied in this way. Both commercially available polymers and those synthesized in our laboratory have been used. On the basis of IET spectra presented here, and existing i.r. spectra it is believed that PMMA and PVA undergo ester cleavage at the oxide surface leading to their subsequent adsorption. For PMMA this is thought to be via carboxylate anions generated on the polymer side groups, while PVA is expected to be adsorbed as PVOH. Bonding of PVOH to the oxide is not fully understood, but may occur by the formation of an AlOC bridge. Another possibility for the above polymers, that of intermolecular hydrogen bonding between polar polymer side groups, and adsorbed hydroxyl species present on the oxide surface, cannot be ruled out.     

Recent developments in biopolymers

Society has been reaping the benefits of industrial polymers for a long time. Polymers have entered every market in a very influential manner, from the packaging industry to the construction business. The very properties that made polymers commercially viable are posing great environmental problems for our future generations. Also, the starting material for most of the commercial polymers is crude oil. Thus, environmental issues coupled with decreasing crude oil reserves have forced the polymer industry to find new sources. These problems having been taken into consideration, biopolymers have emerged as a promising field. This paper takes into consideration the sources of renewable materials, such as starch, lignocellulosic biomass, vegetable oils, proteins, etc.; the synthesis of polymers such as polylactic acid and monomers such as furfural, ethane, propanediol, etc., from renewable materials; and the recent developments in this field. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Synthese elektrisch leitfähiger polymerer

Synthesis of electrically conducting polymers In the last few years electrically conducting polymers have been a centre of scientific interest. Characteristic of these polymers - e. g. polyenes and polyaromatics - are their conjugated double bonds. The addition of electron donators or acceptors causes by the change from insulator properties to electrical conductivity comparable to that of metallic conductors oxidation or reduction of the polymer backbone. Via complex formation a considerable increase in the electron mobility and electrical conductivity is obtained. The aim of the polymer chemist is the synthesis of electrically conducting polymer backbones. An abundance of synthetic routes is available. In addition to the conventional stepwise synthesis using the Wittig-, Horner or Grignard reactions, polycondensation processes and metal-catalysed polymerisat ion techniques can be employed. Oxidative coupling with oxidising Lewis acid catalysts generally leads to polymers with aromatic or heterocyclic units. The Ziegler-Natta-polymerization of acetylenes to filmbuilding polyacetylenes has found broad acceptance; it represents however only one of the many possible reactions, in which reducing agents in combination with transition metals are catalytically active. The polymers synthesised via this process are made electrically conducting by doping. On the other hand the direct polymerisation process e.g. starting from acetylene or aromatics, using the doping agent or via anodic oxidation e. g. from pyrrole, leads directyl to materials with a high electrical conductivity. This paper contains the most important publication with the exception of the patents in the intensively researched field of the synthesis of aliphatic and aromatic polymers with π-electron-conjugation as well as their doping to highly conducting materials.