Crude Polymers Research Articles

Chemical Structures, Properties, and Applications of Selected Crude Oil-Based and Bio-Based Polymers.

The growing perspective of running out of crude oil followed by increasing prices for all crude oil-based materials, e.g., crude oil-based polymers, which have a huge number of practical applications but are usually neither biodegradable nor environmentally friendly, has resulted in searching for their substitutes-namely, bio-based polymers. Currently, both these types of polymers are used in practice worldwide. Owing to the advantages and disadvantages occurring among plastics with different origin, in this current review data on selected popular crude oil-based and bio-based polymers has been collected in order to compare their practical applications resulting from their composition, chemical structure, and related physical and chemical properties. The main goal is to compare polymers in pairs, which have the same or similar practical applications, regardless of different origin and composition. It has been proven that many crude oil-based polymers can be effectively replaced by bio-based polymers without significant loss of properties that ensure practical applications. Additionally, biopolymers have higher potential than crude oil-based polymers in many modern applications. It is concluded that the future of polymers will belong to bio-based rather than crude oil-based polymers.

Unified chromatography: Fundamentals, instrumentation and applications†

The concept of unified chromatography has been in existence for 50 years after the work of Giddings proposing that all modes of chromatography (gas chromatography, liquid chromatography, supercritical fluid chromatography and so on) may be treated together under a single unified theory. His idea was partially fulfilled 23 years later by Ishii, Takeuchi and colleagues, who demonstrated for the first time the possibility to analyze a complex sample containing substances with a wide range of boiling points and polarities in the same instrument and column, just by varying the mobile phase pressure and temperature to change from one chromatographic mode to another. This approach has been demonstrated through application to the separation of complex mixtures in several areas including crude oil, edible oils and polymers. Still, unified chromatography has not yet been fully developed. In the present work, we will review the fundamentals, instrumentation and several applications of the technique. Also discussed are the drawbacks that still hinder development, as well as the recent developments and trends in instrumentation and columns that suggest the most feasible ways forward to the full development of unified chromatography.

Determination and Quantification of Molecular Interactions in Protein Films: A Review.

Protein based films are nowadays also prepared with the aim of replacing expensive, crude oil-based polymers as environmentally friendly and renewable alternatives. The protein structure determines the ability of protein chains to form intra- and intermolecular bonds, whereas the degree of cross-linking depends on the amino acid composition and molecular weight of the protein, besides the conditions used in film preparation and processing. The functionality varies significantly depending on the type of protein and affects the resulting film quality and properties. This paper reviews the methods used in examination of molecular interactions in protein films and discusses how these intermolecular interactions can be quantified. The qualitative determination methods can be distinguished by structural analysis of solutions (electrophoretic analysis, size exclusion chromatography) and analysis of solid films (spectroscopy techniques, X-ray scattering methods). To quantify molecular interactions involved, two methods were found to be the most suitable: protein film swelling and solubility. The importance of non-covalent and covalent interactions in protein films can be investigated using different solvents. The research was focused on whey protein, whereas soy protein and wheat gluten were included as further examples of proteins.

Technofunctional Properties of Films Made From Ethylene Vinyl Acetate/Whey Protein Isolate Compounds

One challenge faced by the plastics industry is that crude oil will become scarcer and more expensive in the future. Furthermore, an increase in plastic waste is leading to a strongly growing demand for sustainable alternatives to traditional, crude oil-based polymers in the packaging sector. The aim of this study was to investigate the influence of the incorporation of whey protein isolates (WPIs) on the technofunctional properties of ethylene vinyl acetate (EVA) films. The compounding EVA with WPI was conducted in a co-rotating twin-screw extruder at varying processing temperatures. WPI and hydrolysed WPI with a degree of hydrolysis of 10% were used up to 35% (w/w) as filler. The tensile strength and elongation at break of the resulting EVA-based films decreased significantly with increasing filler content. Because of the hydrophilicity of WPI, the water vapour permeability of the films increased. Advantageously, the oxygen barrier was enhanced by 50–80% compared with that of pure EVA films, which offered the potential of using whey proteins as a filler in compounds for packaging materials for their oxygen barrier properties. In addition, this study provides a promising perspective on the thermoplastic processing of whey protein formulations in the future. Copyright © 2013 John Wiley & Sons, Ltd.

Economically attractive technologies of deep conversion of associated petroleum gas

Six industrial and emerging catalytic technologies suitable for complete processing of all the components of associated petroleum gas, including methane and ethane, were reviewed. Process schemes for methanol, olefins, synthetic crude oil, gasoline, aromatics, and polymers were considered. A comparative analysis of the technologies in terms of demand for gas feedstock, potential markets for products, capital costs, and other economic indicators was carried out for the associated petroleum gas volumes typical for small and medium-sized oil fields.

Isoselective Styrene Polymerization Catalyzed by ansa-Bis(indenyl) Allyl Rare Earth Complexes. Stereochemical and Mechanistic Aspects

Mechanistic features of the isoselective polymerization of styrene promoted by racemic allyl ansa-lanthanidocene complexes rac-{CMe2(Ind)2}Ln(allyl)(THF)n (Ind =5-indenyl; allyl = C3H5, n = 1, Ln = Y (1), Nd (2); allyl =1,3-(SiMe3)2C3H3, n = 0, Ln = Y (3), Nd (4)), which act as unique single-component catalysts, have been investigated by experimental and theoretical methods. Combined 1H NMR and MALDI−ToF−MS analyses conducted on low molecular weights isotactic polystyrene (iPS) produced by compounds 1 or 2 established the presence of allyl end-groups and therefore that polymerization is initiated by insertion of styrene into Ln−C(allyl). 1H, 2D, and 13C NMR analyses performed on H(D)-iPS-nBu polymers, selectively produced by coordinative chain transfer polymerization (CCTP) of styrene with the binary system 3/Mg(nBu)2 (1:10), evidenced that the polymerization is highly regioselective and proceeds in a secondary insertion mode, both in the initiation and propagation steps. Microstructural analyses of the backbone of crude (unfractionated) polymers produced with 1−4 evidenced a virtually perfect isoselective (mmmmmm > 0.99) polymerization up to 120 °C. Stereoerrors observed in the 13C{1H} NMR spectra of the iPS produced at 130 °C with 1−4 are consistent with an enantiomorphic site control operative during the polymerization. DFT computations of the first and second insertions of styrene in 3 confirmed the above features and the overall mechanistic scenario.

Effects of precipitate agents on temperature-responsive sol–gel transitions of PLGA–PEG–PLGA copolymers in water

This paper reports the effects of precipitate agents used in the collection of block copolymers composed of poly(lactic acid-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) on their thermogelling aqueous behaviors. We synthesized PLGA–PEG–PLGA triblock copolymers with a relatively wide distribution of molecular weight (MW) and then separated the crude polymers via three different precipitate agents (diethyl ether, hexane, or methanol). The obtained products exhibited, however, significantly different macroscopic states in water: some were sols, some were precipitates, and some underwent sol–gel transition upon heating. We found that by using different precipitate agents, ingredients of different MW were collected from the synthesized polymers, which accounted for the different states of the separated products in water. Our study strengthens the importance of an appropriate precipitate agent and reveals the subtle balance of hydrophobicity and hydrophilicity in this sort of amphiphilic block copolymers.

Catalytic Dehydropolymerization of PhSiH3 to Polyphenylsilane with Substituted Group IV Metallocenes

Phenylsilane can be converted catalytically to polyphenylsilane using substituted achiral group IV metallocene dichloride precatalysts (CpR)2MCl2 (M = Ti, Zr; CpR = C5H4C(Me)2CH(Me)2) and Cp(CpR)MCl2 (M = Ti, Zr; Cp = C5H5) in combination with 2 equiv of n-BuLi. The performance of each precatalyst is described in terms of polymer molecular weight, polydispersity, and polymer microstructure. The polysilanes from each catalyst system were obtained as a mixture of oligocyclic and linear materials with Mw values ranging from 1100 to 4000. Characterization of the crude polymers by 1H and 29Si{1H} DEPT 135° NMR spectroscopy indicated a mostly atactic microstructure with a small syndiotactic bias. A Bernoullian statistical analysis of a typical 29Si{1H} polymer spectrum indicated a syndioselective probability (1-Pm) of 0.55 during propagation of the pseudochiral chain. The degree of polymerization was found to be dependent on the metal and the degree of Cp-ring substitution of the metallocene precatalyst.

Something new in the field of PLA/GA bioresorbable polymers?

Polymers issued from glycolic acid and lactic acids (PLAGA) are now used worldwide as bioresorbable devices in surgery and in pharmacology. Their abiotic hydrolytic degradation has been shown to depend on diffusion–reaction phenomena and to proceed homogeneously or heterogeneously, depending on many factors. Two initiators are presently used industrially to make PLAGA polymers by ring opening polymerisation of lactide and/or glycolide in the bulk, namely Sn octanoate and zinc metal. In this contribution, attention is paid to the differences generated by the use of these two initiator systems in the case of the polymerisation of dl-lactide. Various poly( dl-lactide)s were prepared and characterised by size-exclusion chromatography (SEC), differential scanning calorimetry (DSC) and nuclear magnetic resonance spectroscopy (NMR). These polymers were allowed to age in pH=7.4 isoosmolar phosphate buffer at 37°C. Under these conditions, polymers prepared by the two initiator systems showed dramatic differences when the fates of parallel sided specimens of rather large dimensions were considered. These differences were related to the esterification of some of the OH chain ends by octanoic acid and to the presence of rather hydrophobic low molecular weight by-products which were insoluble in the solvent generally used to purify the crude PLAGA polymers. These new findings should be of great interest in the case of PLAGA based matrices aimed at drug delivery.

Synthesis and characterization of α,ω-dichloro-polymethylphenylsilane

The synthesis of a functional polysilane, α,ω-dichloro-polymethylphenylsilane (α,ω-dichloro-PMPS), based on the Wurtz-type reductive coupling, has been considered. A study of some reaction parameters shows that both yield and molecular weight distribution of α,ω-dichloro-PMPS can be greatly influenced by the work-up conditions, reaction time, monomer concentration and temperature during the initiation of the polymerization. By varying the synthesis conditions, different ratios of high and low molecular weight fractions were obtained. Samples of different molecular weight were isolated by fractional precipitation of the crude polymers. The chlorine-end functionalization was confirmed by 29Si NMR spectroscopy and the concentration of end-groups was quantitatively determined by elemental analysis of chlorine.

Enzyme purification with aqueous two-phase systems: comparison between systems composed of pure polymers and systems composed of crude polymers

The main drawback when using aqueous two-phase systems for macromolecule purification is the high cost of most polymers used. The purification of an enzyme, alcohol dehydrogenase, from a crude extract of Saccharomyces cerevisiae was tested in systems composed of poly(ethylene glycol) and a crude hydroxypropyl starch or Reppal PES 100, a purified fraction of hydroxypropyl starch. Purification factors measured for the enzyme were very similar in both systems (between 0.8 and 1.4 for both systems in the upper phase). However, systems composed of Reppal PES present a greater recovery of enzyme, between 77% and 100% versus 60% and 100%, while systems composed of crude hydroxypropyl starch exhibit a larger Δlog K for the tested ligand, 1.26 versus 0.81.

The synthesis and characterization of poly(itaconic) acid

Poly(itaconic acid) (PIA) was obtained indirectly, by the hydrolysis of PIA esters and directly by the polymerization of itaconic acid in water or methanol at 30°C. The first method was not satisfactory but the second gave better results. The elemental composition of the synthetized samples deviated very little from the calculated values. Several crude polymers were fractionated in methanol/isopropanol and the fractions characterized by viscosity and light scattering. The statistically calculated LVN/MW relation, valid for the undissociated polymer, was treated according to the method of Stockmayer and Kurata, to calculate the unperturbed dimensions and to compare them with those of other polymers.

Identification of the ions produced by fast atom bombardment mass spectrometry in some polyesters and polyamides

Fast atom bombardment (FAB) mass spectrometry was applied to the analysis of two polyesters, poly(ethylene adipate) and poly(epsilon-caprolactone), and two polyamides, Nylon 6.6 and Nylon 6. The peaks present in the spectra of the crude polymers were identified as corresponding to protonated molecular ions of preformed cyclic oligomers and of low molecular weight compounds contained in the polymer samples; these species were desorbed intact from the glycerol matrix under FAB conditions. When the polymers investigated were accurately purified from low molecular weight compounds, no significant peaks were observed in their FAB mass spectra. Instead, the FAB mass spectra of the mixtures extracted from the polymers were found to be very similar to those obtained for crude polymers.

Grafting of poly(ethylene oxide) on poly(methyl methacrylate) by transesterification

AbstractThe grafting of the potassium alkoxide derivative of poly(ethylene oxide) on poly(methyl methacrylate) in homogeneous solution in toluene was studied. The alkoxide was prepared by reaction with potassium metal with methanolic potassium methoxide, or with potassium naphthalene. The last was the most suitable for the systematic investigation of the grafting process. Soluble graft polymers were formed, and essentially the initial poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) participated in the production of graft polymer. The composition of the graft polymers and the frequency of grafting of the side chains were determined by NMR. The solubility of the graft polymers in methanol and water increased with increasing PEO contents, while the melting ranges decreased. Fractionation of the crude graft polymers showed that the grafting reaction was random, and graft polymers containing one PEO side chain per about 10–170 MMA units were obtained.

Graft polymerization in solution of methyl acrylate on atactic polypropylene

AbstractThe polymerization of methyl acrylate in an atactic polypropylene solution in the presence of radical initiators (benzoylperoxide, tert‐butylperpivalte, α.α′‐azoisobutyronitrile, Iauroylperoxide) yields a mixture of grafted polymethylacrylate/polypropylene copolymer and a methyl acrylate homopolymer.The crude polymers are fractionated and the influence of the concentration of both monomer and initiator, and of the type ofsolvent used on the percentage of grafting was studied.The concentration of active macroradicals in the grafting reaction is measured with the of a slinplified kinetic scheme.

Highly stereospecific catalytic systems for the polymerization of α‐olefins to isotactic polymers

AbstractThe highly stereospecific catalytic systems for the polymerization of α‐olefins have been compared. These are obtained starting either from the α, γ, or δ modifications of violet TiCl3 with or without AlCl3 present in solid solution, and from aluminum diethyl monohalides, or from metalloorganic products obtained by reacting two molecules of aluminum monoalkyl dihalide with one molecule of particular electron donor compounds. The catalytic systems considered polymerize propylene, giving rise to crude polymers containing 90 to 100% isotatic propylene (nonextractable in boiling n‐heptane) for a wide range of polymerization temperatures. By fractionation of crude polymers prepared with the use of these catalytic systems, highly isotactic polypropylenes, having a melting temperature up to 177°C., have been separated. The results, correlated with those obtained in x‐ray determinations of the structure of the modification of TiCl3 used, demonstrate that the stereospecificity of all the catalytic systems examined is independent of the particular type of violet modification (α, γ, or δ), whether or not these contain aluminum as AlCl3 in solid solution. This proves that the single active centers are substantially of the same type; a variation in their number causes only a variation of the overall polymerization rate.

Studies on the low pressure polymerization of propylene using catalysts containing alkali metal alkyls

AbstractThe low pressure polymerization of propylene was investigated using catalysts prepared from alkali metal alkyls and titanium tetrachloride. In all cases the efficiency of the catalysts depended on the molecular ratio of the metal alkyl to the titanium tetrachloride. In general the polymerization conditions were similar to those for ethylene although the propylene polymerized much more slowly. With n‐butyllithium–titanium tetrachloride, optimum molecular ratios were found between 1.8–2.5, with sharp drops on both sides. With amylsodium–titanium tetrachloride the optimum extended over a wide range (5.7–15), the activity decreasing sharply with lower molecular ratios. The catalysts prepared from sodium alkyls were more active than those prepared from lithium alkyls. Increasing yield was obtained on lowering the concentration of the catalyst. Up to a pressure of about 3 atmospheres, increase in the rate of polymerization was observed with increase in pressure; above this no influence of the pressure was observed. Isotactic polymers were isolated from the polymerization products by successive fractionation of the crude polymers in acetone, ether, and isooctane which dissolved the atactic polymers. With butyllithium–titanium tetrachloride catalysts, at and above optimum ratios, the isotactic fractions were about 60%. At lower ratios there was a great increase in atactic polymers. With amylsodium–titanium tetrachloride catalysts the isotactic fractions were about 70%. Phenylsodium–titanium tetrachloride catalysts were found to be very weak in the polymerization of propylene.

Isotactic polymers of silicon‐containing vinyl monomers

Publisher Summary This chapter discusses isotactic polymers of silicon-containing vinyl monomers. The polymerization of silicon-containing vinyl monomers by means of conventional processes yields only low molecular weight polymers. High molecular weight polymers from monomers containing one vinylic unsaturation and one silicon atom have been prepared by using heterogeneous catalysts which act according to a mechanism of coordinated anionic catalysis. Such polymers contain linear, head-to-tail macromolecules having regular structure, and are crystallizable. By polymerization of allyltrimethylsilane in heptane solution at a temperature of 70–80°C in the presence of catalysts prepared by the reaction of triethyl aluminum with titanium tetrachloride, crude polymers having high molecular weight can be obtained with good yields. The crude polymers, obtained from allyltrimethylsilane, have a silicon content of 24–35% and an intrinsic viscosity in tetralin at 135°C of about 0.5.

A Study of Electrostatic Charges Produced during Mastication of Rubber and of GR-S

Abstract A new electrostatic field strength meter has been described which measures and records, not only the magnitude of electrostatic fields, but also their polarity. This device has been used in a study of the mastication of rubber, and has furnished data which indicate that rubber becomes less negative, and may actually become positive, as mastication proceeds ; this indicates in turn an oxidation of the molecules as well as an electronic rearrangement and orientation of the rubber molecular chains. Data on GR-S polymerized at different temperatures show entirely different electrostatic breakdown curves, which, with other physical characteristics, indicate unusual properties of the crude low-temperature polymers; e.g., high molar weight, long-chain molecules, already or easily oriented, which do not oxidize or break up appreciably on mastication. A partial correlation of Mooney viscosity and electrostatic contact-potential and field strength has been shown for rubber and GR-S which have been masticated on a rubber mill. The new electrostatic-field strength meter shows promise as a new tool which can be used in processing control, and also as a research instrument for obtaining fundamental information on mastication, pigment dispersion and incorporation, as well as an aid in forming new concepts concerning the structure of matter.