Synthesis of Polymers by Using Divalent Metal Salts of Mono(hydroxyethyl)phthalate: Metal-Containing Unsaturated Polyesters

Syntheses of metal-containing unsaturated polyesters based on divalent metal salts (I) of mono (hydroxyethyl)phthalate were investigated by the polycondensation reactions of I-glycols with maleic anhydride (MA)-phthalic anhydride (PA). Among various combinations of components, the systems of MA-PA-diethylene glycol (DEG)-Mg salt, and MA-PA-ethylene glycol (EG)-propylene glycol (PG)-Mg salt gave polyesters soluble in styrene. Viscosities of styrene solutions of the polyesters obtained showed a tendency to increase with increase in metal content in the polyester. The styrene solutions could be cured. The cured polyester resins were evaluated for physical properties. Generally, the polyesters of MA-PA-EG-PG-Mg salt have good physical properties. Further, resistance to chemical attack and boiling water, and thermal behavior are also discussed.     

Synthesis of Polymers by Using Divalent Metal Salts of Mono(hydroxyethyl)phthalate: Metal-Containing Unsaturated Polyesters with Pendent Methacrylate Groups

Syntheses of novel metal-containing unsaturated polyesters having pendent methacrylate groups obtained by use of divalent metal salts of mono(hydroxyethyl)phthalate-maleic anhydride (MA)-glycidyl methacrylate (GMA) reactions were investigated. The yields were generally high. The metal-containing polyesters obtained were slightly yellow-brown solids, and the molecular weights ranged from 1546 to 2174, depending on the mole ratio of feed. Among them, the polyesters obtained at a feed mole ratio of metal salt:MA:GMA of 1:8:8 were miscible with methyl methacrylate (MMA), giving homogeneous solutions suitable for copolymerization, and the polyesters could be easily cross-linked with MMA to give cured resins. The metal-containing cured polyester resins showed excellent physical properties. Resistance of the resins to chemical attack and boiling water and thermal behavior are also discussed.     

Curing reaction of unsaturated (epoxy) polyesters based on different aliphatic glycols

The influence of the structure of succinic or glutaric anhydride modified linear unsaturated (epoxy) polyesters on the course of the cure reaction with styrene initiated by benzoyl peroxide (BPO) or the mixture of benzoyl peroxide/tetrahydrophthalic anhydride (BPO/THPA) or benzoyl peroxide/maleic anhydride, as well as viscoelastic properties and thermal behavior of their styrene copolymers have been studied by DSC, DMA, and TGA analyses. Additionally, mechanical properties: flexural properties using three-point bending test and Brinell’s hardness for studied copolymers were evaluated. It was confirmed that the structure of used polyesters had a considerable influence on the course of the cure reaction with styrene, viscoelastic, thermal, and mechanical properties of prepared styrene copolymers. Generally, one or two asymmetrical peaks for the cure reaction of succinic or glutaric anhydride modified linear unsaturated epoxy polyesters with styrene were observed. They were connected with various cure reaction, e.g., copolymerization of carbon–carbon double bonds of polyester with styrene, thermal curing of epoxy groups, polyaddition reaction of epoxy to anhydride groups in dependence of used curing system. In addition, only one asymmetrical, exothermic peak attributed to the copolymerization process of succinic or glutaric anhydride modified linear unsaturated polyesters with styrene was visible. Moreover, the obtained styrene copolymers based on succinic or glutaric anhydride modified linear unsaturated epoxy polyesters were characterized by higher values of E_{20 ^°\textC}^￠ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T _g, E″, ν _e, E _mod, F _max, hardness, IDT, FDT but lower ε − F _max compared to those values observed for styrene copolymers prepared in the presence of succinic or glutaric anhydride modified linear unsaturated polyesters. This supported to the production of stiffer and more thermally stable polymeric structure of copolymers based on unsaturated epoxy polyesters. Moreover, the copolymers prepared in the use of glutaric anhydride modified linear unsaturated (epoxy) polyesters were described by lower values of E_{20 ^°\textC}^￠ E_{{20\,^{\circ}{\text{C}}}}^{\prime} , T _g, E″, ν _e, E _mod, F _max, hardness, IDT, FDT but higher ε − F _max than those based on succinic anhydride modified linear unsaturated (epoxy) polyesters. The presence of longer aliphatic chain length in polyester’s structure leads to produce more flexible network structure of styrene copolymers based on glutaric anhydride modified linear unsaturated (epoxy) polyesters than those based on succinic anhydride modified linear unsaturated (epoxy) polyesters.     

Synthesis and Characterization of New Unsaturated Polyesters Containing 4‐Phenylcyclohexanone Moiety in the Main Chain

Two series of new unsaturated polyesters were prepared from 2,6‐bis(p‐hydroxidebenzylidene)‐4‐phenylcyclohexanone (I) and 2,6‐divanillyidene‐4‐phenylcyclohexanone (II) with adipoyl, isophthaloyl, sebacoyl and terephthaloyl dichlorides utilizing the interfacial polycondensation technique at ambient temperature. In addition to that, the model compounds were synthesized by reacting (I) and (II) with benzoyl chloride. The model compound and polyester samples have been characterized by elemental and spectral analyses. The unsaturated polyesters have inherent viscosities of 0.96–1.63 dl/g. All the polyesters are amorphous and most of them are partially soluble in most common organic solvents, but easily soluble in concentrated sulfuric acid. Their glass transition temperatures (T_g) range from190.15 to 245.28°C, and the temperatures of 10% weight loss as high as 180 to 220°C in air, indicating that these aromatic polyesters have high T_g and excellent thermal stability.     

Making polymer concrete and polymer mortar using synthesized unsaturated polyester resins from poly(ethylene terephthalate) waste

Depolymerization of poly(ethylene terephthalate), PET, waste was studied in the presence of manganese acetate catalyst and propylene glycol (PG) at different weight ratios. The glycolyzed products were analyzed for hydroxyl value and the amount of free glycol. A series of unsaturated polyesters based on the glycolyzed products, maleic anhydride and styrene, were prepared. Molecular weights and curing behavior of these polyesters were determined. Polymer concrete (PC) and polymer mortars (PM) made with these resins were investigated for their compressive strength. It has been found that the properties of PC and PM obtained from resins based on recycled PET are comparable to PC and PM made from virgin materials.     

Critical aspects related to processing of carbon nanotube/unsaturated thermoset polyester nanocomposites

Carbon nanotubes (CNTs) have outstanding mechanical, thermal and electrical properties. As a result, particular interest has been recently given in exploiting these properties by incorporating carbon nanotubes into some form of matrix. Although unsaturated polyesters with styrene have widespread use in the industrial applications, surprisingly there is no study in the literature about CNT/thermoset polyester nanocomposite systems. In the present paper, we underline some important issues and limitations during the processing of unsaturated polyester resins with different types of carbon nanotubes. In that manner, 3-roll mill and sonication techniques were comparatively evaluated to process nanocomposites made of CNTs with and without amine (NH₂) functional groups and polyesters. It was found that styrene evaporation from the polyester resin system was a critical issue for nanocomposite processing. Rheological behaviour of the suspensions containing CNTs and tensile strengths of their resulting nanocomposites were characterized. CNT/polyester suspensions exhibited a shear thinning behaviour, while polyester resin blends act as a Newtonian fluid. It was also found that nanotubes with amine functional groups have better tensile strength, as compared to those with untreated CNTs. Transmission electron microscopy (TEM) was also employed to reveal the degree of dispersion of CNTs in the matrix.     

Unsaturated,biobased polyesters and their cross‐linking via radical copolymerization

Biobased, unsaturated polyesters derived from isosorbide, maleic anhydride, and succinic acid were synthesized and characterized. The presence of maleic anhydride units in the structure of the polyesters allowed converting them into cured coatings by radical copolymerization with crosslinking agents such as 2‐hydroxyethyl methacrylate, N‐vinyl‐2‐pyrrolidinone, acrylic acid or methacrylamide. The investigated polyesters were obtained via bulk polycondensation, catalyzed by titanium(IV) n‐butoxide. 2D NMR and MALDI‐Tof‐MS spectroscopy proved that this polymerization resulted in isomerization of maleic acid units into fumaric ones and in the formation of slightly branched structures by the reaction of isosorbide (end) groups with main chain unsaturated bonds. Moreover, some double bonds proved to have reacted with the condensation by‐product water. The resulting polyesters displayed the expected correlation between variables such as molecular weight and content of unsaturated bonds and their T_g values. Since the thermal properties of the obtained polyesters were appropriate for coating applications, the polymers were crosslinked with unsaturated monomers by radical copolymerization. The crosslinking process was studied using FTIR spectroscopy and by measurements of the soluble part of the cured coatings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2885–2895, 2010     

Investigation of Conversion of Styrene and Fumarate Double Bonds in Unsaturated Polyester Resins

The conversion of styrene and fumarate double bonds in the copolymerization of unsaturated polyesters and styrene was investigated. Several commercial polyester resins including Bisphenol-type, Iso-type and G-type resins were used. The initial fumarate double bond, the equivalent double bond per 100 g of the polyesters, was determined by the hydrogenation procedure which was developed for the present study. Using palladium-carbon catalyst and benzene-acetone (1:1) mixture, polyester resin can be hydrogenated satisfactorily.

The cured resin was extracted with chloroform. The styrene in the chloroform was determined by ASTM D-1159, bromine index method. The conversion of the fumarate double bond was calculated from the soluble part of polyester resin using the theoretical equations which were derived from the basic theory of Flory. The validity of the equations was examined by application of Funke et al.'s experimental results and found to be satisfactory. With the confidence of these results, commercial polyester resins were investigated to determine the effect of the condition of polymerization on the conversion of styrene and fumarate double bonds.

For all the polyesters the conversion of styrene was at least over 80% after a room temperature cure of 24 hr with a dimethyl anilin-cobalt naphthenate-methyl ethyl ketone peroxide three component catalyst system, and it reached approximately 100% after postcure of 100[ddot]C for 2 hr. On the other hand, the conversion of the fumarate double bond depended greatly upon the type of the resin. Bisphenol-type resin gave the highest conversion, and the conversion for Iso-type resin was higher than that for G-type resin. In the case of Bisphenol-type resin, there was no difference in the conversion of fumarate double bond between the room temperature cure and the postcure, but the conversions of fumarate double bond for G- and Iso-type resins were increased remarkably by postcure. The Barcol hardness is applicable to determine the conversion of styrene for the specified polyesters based on the relationship between the conversion of styrene and the Barcol hardness.     

The influence of chemical modification of unsaturated polyesters on viscoelastic properties and thermal behavior of styrene copolymers

The influence of chemical modification of unsaturated polyesters on viscoelastic properties and thermal behavior of styrene copolymers has been investigated by DMA and TG analyses. Chemical modification of unsaturated polyesters obtained in polycondensation of cyclohex-4-ene-1,2-dicarboxylic anhydride (THPA), maleic anhydride (MA) and suitable glycol: diethylene glycol (DEG) or triethylene glycol (TEG) was performed using 38–40% peracetic acid. It allowed to selective and successful oxidation of carbon-carbon double bonds in unsaturated polyesters giving modified unsaturated polyesters/unsaturated epoxypolyesters/containing both carbon-carbon double bonds in polyester chain and new functional groups-epoxy groups in cycloaliphatic rings. Both unsaturated polyesters and unsaturated epoxypolyesters were used as a component of styrene copolymers cured with different hardeners. It has been demonstrated that the use of modified unsaturated polyesters as a component of styrene copolymers allowed obtaining more stiffness and more cross-linked network structure compared to styrene copolymers based on unmodified polyesters. The higher values of storage modulus, glass transition temperatures and better thermal stability for styrene copolymers based on unsaturated epoxypolyesters were obtained.     

Influence of Residual Polyesterification Catalysts on the Curing of Polyesters

 Unsaturated polyesters are synthesized by means of polyesterification, often with catalysts like strong acids, metal oxides and metal-organic salts. Most often, the catalysts used cannot be separated from the bulk of the polyester. Also, some organic or inorganic additives – called fillers – which are used with the polyester in order to decrease cost, affect the curing of the polyester. In this work the effect of residual catalyst on the curing of unsaturated polyester is studied. Unsaturated polyesters were prepared using propylene glycol with a 10% molar excess over stoichiometry and a mixture of dicarboxylic acids, namely maleic acid (unsaturated) adipic acid (saturated) and phthalic anhydride (saturated) at a molar ratio 1:2:2. Lead dioxide, p-toluenesulfonic acid and zinc acetate were used as catalysts, at 0.1% w/w. After the polyesterification, the polymers were diluted with styrene at a proportion of 100:30 w/w. The resins were cured by using MEKP (methylethylketone peroxide) as initiator and CoNp (cobalt naphthenate) as accelerator. Catalysts affect the final color of the polyester. The kinetics of curing of the resins was studied by DSC analysis based on the exothermic peak due to the double bonds breaking to give crosslinked macromolecules. The heat released ΔH is decreased by the presence of catalyst, while activation energy, the frequency factor and the order of reaction are increased.     

Linear and branched polyester resins based on dimethyl-2,5-furandicarboxylate for coating applications

In this study, novel bio-based hydroxyl-end-capped (co)polyesters from dimethyl-2,5-furandicarboxylate (DMF), 2,3-butanediol, and a variety of comonomers viz. glycerol, pentaerythritol or trimethylolpropane are prepared using a solvent-free, bulk polycondensation technique. Extensive molecular and thermal characterization was performed to elucidate the properties of these materials. The materials showed suitable properties for solvent-borne coating applications in terms of their molecular weight, functionality and thermal characteristics, and coatings were prepared using the isocyanurate of hexamethylene diisocyanate as a cross-linker. The resulting coatings, having thicknesses between 30 and 55 μm, were hard but rather brittle. All the coatings have good solvent resistance, pointing to sufficient network formation. It is clear that the presented DMF-based polyesters show promise as bio-based coating resins.     

Studies on the Cure Reaction and Relationship between Network Structure/Thermal Properties of Styrene Copolymers Based on Adypic/Sebacic Acid Modified Unsaturated (Epoxy) Polyesters

The studies on the relationship between network structure/thermal properties of styrene copolymers based on adypic/sebacic acid modified unsaturated (epoxy) polyesters cured using different hardeners as well as the course of the cure reaction of polyesters with styrene have been presented. The adypic/sebacic acid modified unsaturated polyesters (UP) prepared from 4-cyclohexene-1,2-dicarboxylic anhydride (THPA), maleic anhydride (MA), adypic acid (AA) or sebacic acid (SA) and ethylene glycol (EG) and their epoxy derivatives: adypic/sebacic acid modified unsaturated epoxy polyesters (UEP) were subjected to the cure process with styrene using diacyl peroxide: benzoyl peroxide (BPO) or the mixture of BPO/suitable acid anhydride: 4-cyclohexene-1,2-dicarboxylic anhydride (THPA) or glutaric anhydride (GA). Thermal properties were evaluated by means of DSC, TG and DMA analyses. It was proved that studied properties were significantly depended on polyester's structure and the type of applied curing system. Generally, higher values of E'_20°C, tgδ_max, E”, ν_e, IDT, T_k for styrene copolymers based on UEP were obtained. It was connected with more cross-linked polymer network structure due to the possible copolymerization reaction of carbon-carbon double bonds of polyester with styrene and additional polyaddition of epoxy to anhydride groups or thermal curing of epoxy groups. The additional connections between polyester's chains led to obtain more stiff and thermal stable polymeric materials. Moreover, the increase of saturated aliphatic acid's chain length in polyester backbone caused the decrease of E'_20°C, tgδ_max, E”, ν_e, IDT, T_k values of styrene copolymers. It suggested that copolymers based on polyesters prepared from acid containing more methylene groups in their structure were characterized by more flexible polymer network due to the “laxity” effect of aliphatic chains.     

Properties of Starch Blends with Biodegradable Polymers

Abstract

Starch, one of the most inexpensive and most readily available of all natural polymers, can be processed into thermoplastic materials only in the presence of plasticizers and under the action of heat and shear. Poor water resistance and low strength are limiting factors for the use of materials manufactured only from starch, and hence the modification of starch is often achieved by blending aliphatic polyesters. In this review, the literatures concerning the properties of various blends of starch and aliphatic polyesters have been summarized. The biodegradable rates of blends can be controlled to a certain extent depending on the constitutions of blends, and the mechanical properties of blends are close to those of traditional plastics such as polyethylene and polystyrene. The reduction of their sensitivity to humidity makes these materials suitable for the production of biodegradable films, injection-molded items, and foams.     

Synthesis and characterization of new unsaturated polyesters and copolyesters containing azo groups in the main chain

A new interesting class of linear unsaturated polyesters based on dibenzylidenecycloalkanones have been synthesized by interfacial polycondensation of 4,4^′-azodibenzoyl chloride or 3,3^′-azodibenzoyl chloride with: 2,5-bis(p-hydroxybenzylidene)cyclopentanone I, 2,6-bis(p-hydroxybenzylidene)cyclohexanone II, 2,6-divanillylidenecyclohexanone III, or 2,7-bis(p-hydroxybenzylidene)cycloheptanone IV at ambient temperature. The copolyesters are also synthesized from the monomers I, II, III or IV with the diacid chlorides. The resulting polyesters and their copolyesters were characterized by elemental analyses, IR spectroscopy and solubility. Additionally, inherent viscosity of the polyesters in the range 0.32-0.86 dL g⁻¹ and the inherent viscosity of the copolyesters in the range 0.28-0.65 dL g⁻¹ were determined. The UV-visible spectra of certain polymers were measured in m-cresol solution and showed a characteristic absorption band at 435-473 nm due to n-π^* transition. The thermal properties of the polymers were evaluated by thermo gravimetric analysis and differential scanning calorimetry measurements and correlated with their structural units. The crystallinity of some polyesters and copolyesters were tested. In addition, the electrical properties of all polyesters and copolyesters were measured.     

Synthetic Approaches to Combine the Versatility of the Thiol Chemistry with the Degradability of Aliphatic Polyesters

Abstract

Thiol chemistry is an efficient tool to manipulate the microstructure of aliphatic polyesters and open the way to different applications. Synthetic strategies that aim to synthesize thiol-functionalized aliphatic polyesters are reviewed herein. The introduction of thiol-editable groups on aliphatic polyesters can occur both at chain ends and along the chains, enabling diverse modifications of the polymeric chains and imparting new properties and functions. The use of thiol chemistry for postpolymerization modification of this class of polymers and the (co)polymerizations of monomers bearing thiol groups has also been described herein.     

Synthesis and characterization of biodegradable poly(butylene succinate-co-butylene fumarate)s

A series of aliphatic biodegradable polyesters modified with fumaric residues was synthesized by transesterification in the melt of dimethyl succinate, dimethyl fumarate and 1,4-butanediol. The amount of unsaturation, originating from the fumaric acid residues in the polyesters chains was varied from 5 to 20 mol%. The molecular structure and composition of the polyesters were determined by ¹H NMR spectroscopy. The effects of the content of fumaric residues on the thermal and thermo-oxidative properties of the synthesized polyesters were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis. The degree of crystallinity was determined by DSC and wide angle X-ray scattering. The degrees of crystallinity of the unsaturated copolyesters were reduced, while the melting temperatures were higher in comparison to poly(butylene succinate). Biodegradation of the synthesized copolyesters was estimated in enzymatic degradation tests using a buffer solution with Rhizopus arrhizus lipase at 37 °C. Although the degree of crystallinity of the copolyesters decreases slightly with increasing unsaturation, the biodegradation is not enhanced suggesting that not only the chemical structure and molecular stiffness but also the morphology of the spherulites has an influence on the biodegradation properties. The highest biodegradability was observed for the copolyesters containing 5 and 10 mol% of fumarate units.     

New Phosphorus-Containing Flame Retardants for Poly-Urethanes and Polyesters

Abstract

New phosphorus - containing monomers and oligomers from tetrakis(hydroxymetyl)phosphonium chloride and dialkylphosphites are synthesized. On the basis of new products phosphorus-containing polyesters, polyurethanes and polyuretanesemicazbazides with improved fire resistance are obtained. The dependence of fire resistance of the polymers on the structure of the use flame retardants is investigated.     

Insights into post‐polymerisation modification of bio‐based unsaturated itaconate and fumarate polyesters via aza‐michael addition: Understanding the effects of CC isomerisation

Development of renewable bio‐based unsaturated polyesters is undergoing a renaissance, typified by the use of itaconate and fumarate monomers. The electron‐deficient CC bond found on the corresponding polyesters allows convenient post‐polymerisation modification to give a wide range of polymer properties; this is notably effective for the addition of nucleophilic pendants. However, preservation of unsaturated functionality is blighted by two undesirable side‐reactions, branching/crosslinking and CC isomerisation. Herein, a tentative kinetic study of diethylamine addition to model itaconate and fumarate diesters highlights the significance of undesirable CC isomerisation. In particular, it shows that reversible isomerisation from itaconate to mesaconate (a poor Michael acceptor) is in direct competition with aza‐Michael addition, where the amine Michael donor acts as an isomerisation catalyst. We postulate that undesired formation of mesaconate is responsible for the long reaction times previously reported for itaconate polyester post‐polymerisation modification. This study illustrates the pressing need to overcome this issue of CC isomerisation to enhance post‐polymerisation modification of bio‐based unsaturated polyesters. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1935–1945