Synthesis of vegetable oil based polyol with cottonseed oil and sorbitol derived from natural source

In order to prepare the polyol with all bio-based components as raw materials,cottonseed oil was first epoxidized by peroxyformic acid generated in situ from hydrogen peroxide and formic acid,and the cottonseed oil based polyols with variable hydroxyl value were then prepared by the ring-opening of epoxidized cottonseed oil with sorbitol,which is a multi-functional hydroxyl compound derived from a natural source.The chemical structure of the products was characterized with FTIR analysis, and the residual...     

Polymerization of epoxidized triglycerides with fluorosulfonic acid

The use of triglycerides as agri-based renewable raw materials for the development of new products is highly desirable in view of uncertain future petroleum prices. A new method of polymerizing epoxidized soybean oil has been devised with the use of fluorosulfonic acid. Depending on the reaction conditions, one can get a viscous oil or a solid as the reaction product. The reaction mechanism has been studied through a systematic examination of the fluorosulfonic acid-initiated reaction of epoxidized methyl oleate and epoxidized methyl linoleate. Through ¹³C NMR spectroscopy, the major species derived from fluorosulfonic acid-initiated polymerization of epoxidized soybean oil have been determined. The effects of temperature, initiator dosage, and reaction time have been studied and shown to affect the nature of polymer products obtained and the distribution of different chemical species present.     

Polymer particle formation in suspension polymerization of vinyl chloride and vinyl acetate

Equipment has been designed and assembled in such a way that direct microscopic observation of polymer particle formation in suspension polymerization of vinyl chloride and vinyl acetate is possible. The apparent mode of transformation from monomer droplets into polymer particles has thus been studied under two sets of conditions: (1) with agitation and (2) without agitation. In both cases, as the initial vinyl acetate/vinyl chloride ratio was raised, the apparent change in the shape and transparency of particles occurring during the course of polymerization became less evident. In vinyl chloride homopolymerization and vinyl acetate–vinyl chloride copolymerization with relatively high vinyl chloride concentrations, the polymer particles burst during the course of polymerization. Some factors which affect the change in the size of particles are also discussed.     

Anionic polymerization of vinyl chloride

Anionic polymerization of vinyl chloride has been studied. Of the organometallic compounds tested as initiators, only butyllithium was found to initiate polymerization. Polymerization in bulk at 0°C and with tert-butyllithium as initiator gave poly(vinyl chloride) in a yield of 38% with M _n = 55,000. Tacticity of the anionic PVC was similar to that of conventional PVC prepared at similar temperatures. Anionic PVC was found to be less branched and more heat-stable than the conventional polymer.     

Mechanism of vinyl chloride polymerization

An overall mechanistic scheme for the suspension polymerization of vinyl chloride is presented. The process can be resolved into five discrete stages, each of which presents a unique environment for the interaction of the systems parameters. It is shown that the surface area of the polymer formed during the reaction is not a major factor in autoacceleration and that the increase of kinetic chain length with conversion is due to a radical dilution effect. The latter is a direct result of the difference in rates between polymerization and radical formation, the former being greater. The increase of the initial polymerization rate and the reduction of autoacceleration brought about by chain transfer agents can be explained by the lower diffusion rate and greater bulkiness of the chain transfer agent radical relative to that of the monomer radical. The chaintransfer agent CBr₄ is preferentially absorbed by PVC from solution in vinyl chloride. With lauryl peroxide as initiator it is shown that the “hot spot” is the result of a build-up of initiator in the monomer caused by its exclusion from the polymer phase. Vinyl chloride was found to dissolve 0.03% PVC at ambient temperature and to have no effect on the decomposition rate of lauryl peroxide.     

Radiation-induced bulk polymerization of vinyl chloride under centrifugation

Radiation-induced bulk polymerization of vinyl chloride has been carried out under centrifugation at 21°C. The polymerization rate and the molecular weight of the polymer produced were found to remain constant in the low-conversion region and to be equal to the corresponding values that were obtained by extrapolation at zero conversion in normal polymerization. This was at variance with the case of normal polymerization in which both quantities exhibit a continuous increase from the start of the polymerization. Such an increase is to be associated with the presence of large agglomerates, formed through flocculation of initially originated particles, in the liquid monomer phase during the polymerization under quiescent conditions. For the constancy of the kinetic parameters in the polymerization under centrifugation it should be assumed that in the system there remain dispersed only particles not yet flocculated.     

Polymerization of vinyl chloride in the presence of precipitants. I

The kinetics of bulk and precipitation polymerization of vinyl chloride has been studied over wide range of reaction temperature by using γ-ray induced initiation. The autoacceleration effect, which has been observed by many investigators in the case of chemically initiated bulk polymerization of vinyl chloride above 40°C and has been the most controversial aspect of the bulk polymerization of vinyl chloride, was found to disappear in the bulk polymerization below 0°C. In the bulk polymerization at 40°C, the autoacceleration effect was observed up to 20%, in agreement with the results of previous investigators, and a pronounced effect of the size of polymer particles on the time–conversion curve was observed. The kinetics of precipitation polymerization of vinyl chloride in the presence of some nonsolvents was successfully described by a oneparameter equation. A kinetic scheme, which clearly explains the zero-order reaction behavior of bulk polymerization at low temperature and the kinetic behavior of precipitation polymerization described by the empirical equation, is proposed. The autoacceleration effect in the bulk polymerization at 40°C was considered to be essentially the same phenomenon as the small retardation period observed in the bulk polymerization at low temperature.     

High-pressure polymerization of vinyl chloride

The radical polymerization of vinyl chloride was investigated at 60°C under high pressure up to 5000 bar in benzaldehyde, benzonitrile, toluene, heptane, cyclohexane, and dioxane as solvent. In benzaldehyde and benzonitrile, the polymerizations were depressed by increased pressure. This unusual behavior was explained by the solvent participation and the effect of pressure on the propagating radicals. The crystallinities of polymer obtained in all solvents decreased with increasing pressure, as judged by the absorbance ratio of the infrared spectra. However the effects of pressure on the absorbance ratio of the polymer obtained in benzaldehyde and benzonitrile were not identical with those in the other solvents. These facts also suggest that both solvents play a special role for the solvent participation in the propagating step.     

Suspension polymerization of vinyl chloride and the processibility of poly(vinyl chloride)

The most important technological procedure in the production of PVC is the suspension polymerization of vinyl chloride, as processibility of the polymer may be influenced to a considerable extent by the choice of polymerization conditions. Structure heterogeneities in PVC powders manifest themselves in plasticized PVC by the occurrence of “fish eye” particles. This review concerns the formation and properties of these particles and discusses the causes of their difficult processibility. Also, the relation between polymerization process and PVC dehydrochlorination is discussed and a new mechanism of its initiation based on the reactivity of cisoid enone structures is proposed. These structures catalyze elimination of hydrogen chloride from regular units of PVC by an interchain enzyme-like mechanism giving rise to chloroallyl structures.     

Studies on poly(vinyl chloride). III. The role of the precipitated polymer in the kinetics of polymerization of vinyl chloride

In polymerization of vinyl chloride monomer, free radicals precipitate on or within aggregates of partially swollen dead polymer. Polymerization on the solid polymer is characterized by autoaccelerating rates due to a progressive reduction in termination rate. This reduction in termination rate is due to the fact that as the reaction progresses and more polymer accumulates there is a decrease in probability that chain transfer of polymer radicals to monomer will generate a mobile radical, which can readily terminate an occluded or stuck free radical. From the appearance of the particles of solid polymer in the system, it has been concluded that free radicals precipitate both on polymer particle surface and inside the open structure of polymer particles.     

FTIR investigation of the specific migration of additives from rigid poly(vinyl chloride)

Commercial sunflower oil was epoxidized and used as organic costabiliser for rigid poly (vinyl chloride) (PVC) containing zinc and calcium stearates as primary stabilisers and stearic acid as lubricant. For applications in the packaging of foodstuffs, migration testing must be realised. For that purpose, two food simulants were used (sunflower oil and 15% (v/v) aqueous ethanol). The test conditions were 12 days at 40 °C. Circular samples of rigid PVC were immersed in a well known volume of food simulant. A circular sample and 10 ml of food simulant were taken off every day to be analysed. The specific migrations of the additives were investigated by using Fourier transform infrared spectroscopy.The direct analysis of the food simulants was difficult because overlapping of the bands of the additives. However, the analysis of PVC films obtained by dissolution of the circular samples in tetrahydrofuran and evaporation of the solvent was more conclusive. The specific migrations of the metal carboxylates and epoxidized sunflower oil were evidenced.     

Pyrolysis of poly(vinyl chloride)

A pyrolysis–gas chromatography–mass spectrometric technique has been developed to study the thermal degradation of poly(vinyl chlorides) polymerized at different temperatures. Hydrogen chloride and benzene evolution during successive stages of pyrolysis have been quantitatively determined and correlated to the tacticity and molecular weight of the polymer. It was found that lowering the temperature of polymerization and molecular weight depresses benzene evolution and increases char weight but does not affect the HCl yield. It is suggested that the syndiotactic trans microstructure favored at low temperature of polymerization yields polyenes which cannot cyclize to form benzene. As the molecular weight decreases, the increase in number of vinyl chain ends facilitates pyrolytic crosslinking and char formation.     

NMR spectrum of poly(vinyl chloride)

The 100-MHz proton NMR spectra of commercial and laboratory-prepared poly(vinyl chloride) (PVC) have been measured in various solvents at high temperature (80–150°C). Tacticity in PVC was determined by the analysis of the β-proton spectrum. The spectrum was calculated assuming that the PVC chain consists of tetrad sequences of monomer units and that their distribution in the chain is described by a simple Bernoulli-sequence statistics with a P_m (the probability of isotactic placement) of 0.45 for commercial PVC polymerized at 50°C. Tacticity calibration curves based on measurements made for the polymer in pentachloroethane and β-dichlorobenzene were established, and they provide a simple method for the measurement of tacticity in PVC directly from the observed spectra. Excluding samples prepared in butyraldehyde solution, the formation of syndiotactic structures in PVC (prepared by free-radical polymerization) was found to be favored by lowering the polymerization temperature. This preference is due to an increase in the activation enthalpy of 510 cal/mole which is required for forming an isotactic placement in the chain during the propagation step.     

4-Vinylbenzenesulfonic acid adduct of epoxidized soybean oil: Synthesis, free radical and ADMET polymerizations

In this work new radically polymerizable triglyceride based monomers were synthesized by the reaction of epoxidized methyl oleate (EMO) and epoxidized soybean oil (ESO) with 4-vinyl benzene sulfonic acid (4VBSA). The products are 1-(4-vinylbenzene sulfonyl)oxy-2-alkonols of epoxidized soybean oil (SESO) and 1-(4-vinylbenzene sulfonyl)oxy-2-alkonols of epoxidized methyl oleate (SEMO). These adducts were characterized by ¹H NMR, ¹³C NMR, IR and CHNS elemental analysis. SESO was found to contain, on the average, 2.47 4VBSA units per triglyceride. SESO was free radically polymerized and co-polymerized with styrene and the mechanical and thermal properties of the resulting thermosets were determined by DMA, DSC and TGA. SEMO was used as a model compound to determine the efficiency of metathesis catalysts for these fatty acid derivatives. The second generation Hoveyda–Grubbs catalyst was found to give best yields. ADMET polymerization of SESO with this catalyst with and without solvent gave ∼80% yield of a thermoset polymer. Polymers obtained by free radical route swelled in water at room temperature, and hydrolyzed in water at 60 °C.     

Electrical conductivity in vinyl chloride during polymerization

Vinyl chloride of good polymerization quality showed a measurable electrical conductivity. The ionic strength of redistilled VCM appeared to be independent of temperature in the range from 20 to 50°C, and to decrease at higher temperatures. Conductivity measurements during bulk polymerization of VCM showed that the conductivity decreased with conversion. Other results indicated that electrolytically active species, formed during the polymerization, were trapped in the polymer matrix.     

Characterization and thermal stability of poly(vinyl chloride) plasticized with epoxidized soybean oil for food packaging

The use of phthalates in plasticized poly(vinyl chloride) (PVC) formulations has been questioned by their potential toxicity and high migration to foodstuff. Phthalates can be replaced by other harmless and environmentally friendly plasticizers, such as epoxidized soybean oil (ESBO), which has been also proved an efficient stabilizer for PVC helping to prevent degradation during processing. Formulations based on PVC with different amounts of ESBO (from 30 to 50 wt%) were fully characterized showing good compatibility and a clear increase in thermal stability. An evaluation of the use of ESBO for PVC stabilization in commercial lids was carried out by using thermogravimetric analysis (TGA). ESBO was detected in all materials and their thermal stability was highly dependent on the plasticizer concentration. Most of them showed a significant increase in thermal degradation temperatures, permitting their use in food processing at high temperatures without risk of degradation.     

Kinetics of radiation-induced bulk polymerization of vinyl chloride in the temperature range of −50 to 90°c

Kinetic investigations on the bulk polymerization of vinyl chloride initiated by exposure to ⁶⁰Co γ-rays were carried out in the temperature range of ?50 to 90°C at dose rates varying from 0.15 to 50 rad/c. Some polymerization runs were also carried out in a centrifugal field. As generally reported for this polymerization system, in which the polymer is insoluble in the monomer, the polymerization rate was found to change as a function of the amount of the polymer formed in a special fashion. This particular function has been shown to be greatly influenced by the polymerization temperature and to be independent of the rate of initiation, or, more rigorously, of the dose rate. Thus, at any given temperature the equation of the polymerization conversion rate could be written in the form of the product of two separate functions, one for the polymerization conversion and the other for the dose rate. While for the latter the results gave an essentially square-root dependence on dose rate as is normally found for homogeneous polymerization, the former has been discussed in the terms of recently advanced kinetic schemes, based on a two-phase polymerization model. The kinetic parameters found in this work are in agreement with previous authors' data.     

Kinetic study of early stages of heterophase polymerization of vinyl chloride initiated by radiation

The kinetics of the radiation-induced bulk polymerization of vinyl chloride in the early stages was determined in the temperature range of ?30 to 50°C and dose rates varying from 0.6 to 17 rad/sec by the dilatometric method. Some runs of polymerization of vinyl chloride added with different percentages of tetrahydrofuran were also carried out. The results were found to agree with those previously obtained with polymerizations carried out to high conversions. The results are discussed on the assumption of a decrease in the extent of swelling of the polymer by monomer with decreasing polymerization temperature. By comparison with the data of other precipitating polymerization systems the possibility of a generalized interpretation for the heterophase polymerization is examined.     

A new kinetic model for bulk polymerization of vinyl chloride based on two-phase hypothesis

A kinetic model has been developed for the bulk polymerization of vinyl chloride using Talamini's hypothesis of two-phase polymerization and a new concept of kinetic solubility which assumes that rapidly growing polymer chains have considerably greater solubility than the thermodynamic solubility of preformed polymer molecules of the same size and so can remain in solution even under thermodynamically unfavourable conditions. It is further assumed that this kinetic solubility is a function of chain length. The model yields a rate expression consistent with the experimental data for vinyl chloride bulk polymerization and moreover is able to explain several characteristic kinetic features of this system. Application of the model rate expression to the available rate data has yielded 2.36 × 10⁸l mol^?1 sec^?1 for the termination rate constant in the polymer-rich phase; as expected, this value is smaller than that reported for homogenous polymerization by a factor of 10–30.     

Vanadium alkoxide catalyzed polymerization of vinyl chloride

The polymerization of vinyl chloride (VC) with vanadium complex/alkylaluminum catalyst was investigated. In the case of polymerization with vanadium oxytriethoxide (VO(OEt)₃), poly(vinyl chloride) was obtained in a good yield. The effect of cocatalyst, solvent, and cocatalyst/precatalyst ratio was observed. The structure of the polymer obtained with VO(OEt)₃/i‐Bu₃Al catalyst consisted of regular head‐to‐tail sequence and isobutyl chain‐end structure. VO(OEt)₃/alkylaluminum catalyst was able to copolymerize VC with styrene, 1‐butene, methyl methacrylate, and methyl acrylate. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011