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The humus-accumulative horizon of a typical chernozem (Haplic Chernozem (Loamic, Pachic)) under different land uses has been studied with the thermal method and IR spectroscopy. According to our data, the organic matter of chernozem mainly consists of thermally weakly stable aliphatic compounds, such as polysaccharides. This is indicated by a considerable weight loss (68.15–71.54%) in the low-temperature region, which varies and an intense absorption band at 1083 cm–1, which determines the shape of the IR spectra of chernozem. An extensive agricultural use has caused the mineralization of labile aliphatic compounds and an increase in stable cyclic structures in the composition of the organic matter of chernozem. This is indicated by a decrease in the Chernikov–Konchits Z coefficient from 3.16 to 2.47–2.73 and in the intensity of most absorption bands in the IR spectra. The most pronounced negative impact on the organic matter of a typical chernozem is caused by bare fallow. [ABSTRACT FROM AUTHOR]

Abstract: In the present research, a type of cycloaliphatic silicone–epoxy resin is synthesized and then compounded with acrylates as well as photoinitiators to obtain hybrid photopolymers. The photocuring rate of the hybrid photopolymers, the morphology, thermal and mechanical properties of the cured samples with different silicone–epoxy/acrylate ratios are studied in detail. Scanning electron microscopy images prove that interpenetrating polymer network structure is formed. To improve the mechanical properties, diglycidyl ether of bisphenol A is added and finally a type of hybrid photopolymer suitable for stereolithography 3D printing is obtained. Fourier‐transform infrared spectroscopy and photo‐differential scanning calorimeter measurements show that the hybrid photopolymer has a high curing rate, while thermal property tests prove that the cured sample has high thermal stability. Mechanical property tests show that the cured samples have a tensile strength of 40.3 MPa with a break elongation of 6.7%. The objects printed with the hybrid photopolymer exhibit high resolution and dimension accuracy. [ABSTRACT FROM AUTHOR]

In the presented work, the effect of crosslinker geometry on the properties of PVA is reported. The aliphatic (suberic) and aromatic (terephthalic) dicarboxylic acids are used as crosslinker molecules. On the basis of tensile test and thermal properties, it is observed that crosslinking of PVA by suberic acid is more effective than terephthalic acid. The maximum strength measured in crosslinked samples is 32.5 MPa for suberic acid crosslinked PVA which is higher than that of neat PVA (22.6 MPa). Swelling study shows that 8 h crosslinked terephthalic acid (35% w/w) samples have a minimum of 5.4% of water uptake compared to neat PVA, which dissolves readily in water. DTGA shows that the decomposition temperature of crosslinked PVA is 345 °C while neat PVA has a decomposition temperature of 315 °C. FTIR spectroscopy confirms the formation of crosslink ester bond in crosslinked PVA. The crosslinked samples kept for bio-degradation show maximum degradation in terephthalic acid (15% w/w) crosslinked PVA. [ABSTRACT FROM AUTHOR]

Five novel bridged heptaphenyl polyhedral oligomeric silsesquioxanes (POSSs), in which two identical silicon cages R7(SiO1.5)8 (with R = Phenyl) are linked to various aliphatic [(CH2)n with n = 2, 6 and 10] and aromatic (Ar–Ar and Ar–O–Ar, where Ar = p-C6H4) bridges, were synthesized. The obtained compounds were characterized by elemental analysis and 1H NMR spectroscopy, and the results were in very good agreement with those of expected products. The synthesized heptaphenyl POSSs were thermally degraded, in dynamic heating conditions (25–700 °C), in both flowing nitrogen and static air atmosphere. The temperatures at 5% mass loss (T5%) and residues at 700 °C were thus determined to evaluate their resistance to thermal degradation, but no substantial difference was found between the values in the two studied environments. The obtained T5% values were much higher than those of the corresponding isobutyl and cyclopentyl POSSs we investigated in the past. Also, the T5% values of the phenyl POSSs with aliphatic bridges decreased quite linearly on increasing the number of bridge carbon atoms (nC). This behaviour was interpreted and attributed to the presence of the external corona formed by voluminous phenyl groups. The residue at 700 °C, which was largely higher than those of the corresponding isobutyl and cyclopentyl POSSs, was a further confirmation of the better thermal stability of the compounds here studied. [ABSTRACT FROM AUTHOR]

Biobased short aliphatic diols and diethyl carboxylates were enzymatically (co)polymerized in solution at mild temperature using the immobilized form of Candida antarctica lipase B (CALB) as biocatalyst. The influence of the monomer structure on the CALB activity was investigated. CALB showed a better affinity for 1,4-butanediol compared to 1,3-propanediol (1,3-PDO), whereas no preference was observed between diethyl succinate and diethyl adipate. In addition, two series of random copolyesters [poly(butylene succinate- ran -butylene adipate) (PBSA) and poly(propylene succinate- ran -butylene succinate) (PPBS)] were synthesized at different compositions to investigate the effect of the composition on copolyesters, which were fully characterized by various chemical and physico-chemical techniques including NMR, SEC, WAXS, DSC and TGA. Their compositions were similar to the feed ones, despite the activity difference of the monomers towards CALB. Nevertheless, this activity difference resulted in the decrease of the M w of PPBS from 24 to 11 kg/mol for 1,3-PDO content varying from 0 to 100 mol.%. Moreover, 1,3-PDO induced an increase of T g and a decrease of the crystallization rate until having an amorphous behavior for high 1,3-PDO content. On the other side, the reduction of the diethyl carboxylate chain length from diethyl adipate to diethyl succinate did not induce a clear tendency with M n varying from 22 to 12 kg/mol with the succinate content. Furthermore, T g increased with the succinate content and the good thermal stability of copolyesters were dependent on the diethyl carboxylates composition. Finally, both copolyesters exhibited an isodimorphic co-crystallization behavior. [ABSTRACT FROM AUTHOR]

This work describes the synthesis and structure of the new segmented polyurethanes (SPURs) formed from an aliphatic diisocyanate [1,1′-methanediylbis(4-isocyanatocyclohexane] ( Desmodur W®) and unconventional sulfur-containing chain extender [2,2′-methylenebis([4,1-phenylene]methylenesulfanediyl)diethanol]. Soft segments were poly(oxytetramethylene)diol of [ABSTRACT FROM AUTHOR]

A telechelic thiol functionalized poly( p -phenylene sulfide) oligomer (SPPSO) was prepared by the reaction of 1,4-dichlorobenzene and excess sodium sulfide. 4,4′-Bismaleimidodiphenylmethane (BMI) was prepolymerized with various molar ratios of SPPSO, a pentaerythritol-based tetrathiol (S4P) and an isocyanurate-based trithiol (S3I) at the maleimide/SH ratio of 1/1 at 200 °C in the presence or absence of dimethylphenylphosphine (Me 2 PPh) and then compression-molded at finally 210–230 °C to produce cured resins (BMI-SPPSO, BMI-SPPSO/S4P, BMI-SPPSO/S3I, BMI-S4P and BMI-S3I). The FT-IR analysis revealed that the maleimide and thiol groups of all the cured resins were almost consumed by the thermal thiol-Michael reaction. Although the temperature at which the thiol-maleimide reaction starts to occur was reduced by the addition of Me 2 PPh, the flexural strength, modulus and thermal degradation temperature for the cured resins with Me 2 PPh were rather lower than those for the cured resins without Me 2 PPh. Regarding the cured resins without Me 2 PPh, BMI-SPPSO/S4P 2/1 and BMI-SPPSO/S3I 2/3 exhibited the highest flexural strength and modulus among BMI-SPPSO/S4Ps and BMI-SPPSO/S3Is, respectively. The glass transition temperature ( T g ) and 5% weight loss temperature ( T d5 ) for the cured resins increased with increasing SPPSO/S4P or SPPSO/S3I ratio, and BMI-SPPSO exhibited the highest T g (170 °C) and T d5 (442 °C). [ABSTRACT FROM AUTHOR]

The aliphatic-aromatic copolyester, poly(butylene adipate-co-terephthalate) (PBAT) combines good mechanical and thermal properties with biodegradation ability. However, until now, researches in its potential medical use remain limited. Only in a few studies blends of PBAT with routinely used biocompatible polymers had been prepared and investigated regarding tissue engineering applications. Therefore, in this study, we decided to determine processability of neat PBAT as a scaffold material for bone tissue by using different fabrication methods i.e. solvent evaporation, electrospinning, solvent casting-particulate leaching (SCPL) and melt molding-particulate leaching. The results of physicochemical characterizations and cell culture studies with MC3T3-E1 preosteoblasts confirmed that neat PBAT has favorable characteristics for bone tissue engineering, however, fabrication method strongly affects the cellular responses. Regarding to the characterizations and cell cultures, PBAT scaffolds produced by SCPL and electrospinning are proposed to be used for bone tissue engineering. [ABSTRACT FROM AUTHOR]

This study reports the influence of aliphatic-aromatic copolyesters (AAC) on selected polylactide (PLA) properties. Processing, mechanical, and thermal properties were determined. In addition, we examined changes occurring in the surface geometrical structure of sample fractures. It was found that PLA as modified with AAC exhibited enhanced impact strength and melt flow rate, unaffected elongation at break, and reduced tensile strength and elasticity modulus. The results also demonstrate the plasticizing properties of AAC, which improved PLA processing and its thermal stability. We also observed insufficient adhesion at the interface between the two components, as well as heterogeneity of the obtained material. [ABSTRACT FROM AUTHOR]

A series of poly(ether-ester)s containing cardo cyclohexane moiety in the main chain was synthesized from 1,1-bis (4-(3-hydroxypropyloxy)phenyl) cyclohexane (BPPZ) and aliphatic and aromatic acid chlorides. The diol monomer, BPPZ, was synthesized from 1,1-bis (4-hydroxyphenyl) cyclohexane (BPZ) and 3-bromo-1-propanol. The solubility of the polymers was tested in various solvents. The intrinsic viscosity of the synthesized polymers was determined by Oswald viscometer and found to be 0.33-0.48 g/dl. The molecular structures of the monomer and polymers were confirmed by Fourier transform InfraRed, H-NMR and C-NMR spectral analyses. The thermal properties were studied with thermogravimetric analyses and differential scanning calorimetry. The thermogravimetric analyses data revealed that the polymers were stable up to 190 °C, and start degrading thereafter. The solubility and thermal stability of the synthesized polymer is enhanced due to the introduction of methylene spacer with ether group into the polymer chain backbone. The self-extinguishing property of the synthesized polymers was studied by the determination of limiting oxygen index values with Van Krevelen's equation. [ABSTRACT FROM AUTHOR]

Five wax ester oligomers of oleyl oleate (monomer to pentamer) produced from the self-metathesis of oleyl oleate derived from soybean oil were separated from the crude metathesis product by column chromatography. The purified compounds contained trans - and cis - configurations with a trans/cis ratio ranging from 3.6 for the monomer to 6.6 for the pentamer. The thermal transition behaviour of the oligomers as revealed by DSC was directly related to their trans - and cis - composition. Although odd/even effects presented predictable deviations, the crystallization and melting characteristics such as temperature and enthalpy scaled predictably with molecular size, and demonstrated a diminishing effect of incremental increases in monomer units. As determined by TGA, and except for the monomer which started to evaporate at ∼200 °C, the oligomers presented excellent thermal stability with onsets of degradation higher than 360 °C. The thermal transition characteristics of the monoester oligomers are comparable to commercial waxes and show potential for their use in a large range of wax applications ranging from viscous fluids to hard brittle solids. Furthermore, the thermal transitions occurred over narrow temperature spans, a feature that is useful for applications requiring collimated melting and crystallization ranges. [ABSTRACT FROM AUTHOR]

In the current manuscript two new furan based polyesters, namely poly(pentylene furanoate) (PPeF) and poly(heptylene furanoate) (PHepF), have been synthesized for the first time using 2,5-furandicarboxylic acid (2,5-FDCA) and aliphatic diols with odd number of methylene groups (5 and 7 respectively) via melt polycondensation method. Their structural characteristics and thermal properties are presented in detail. [ABSTRACT FROM AUTHOR]

Various acids such as aliphatic or carbocyclic fatty or aromatic acids were successfully conjugated into the ending hydroxyl group of poly( l-lactide) (PLLA). The chemical structures of various acid-PLLAs were confirmed by Fourier transform infrared and proton nuclear magnetic resonance analysis. The crystallinity and solubility of the original PLLA were maintained after the terminal conjugation of various acids. The thermal properties were significantly improved, especially the 10% weight-loss temperature that showed an increase of over 80°C for conjugation of aliphatic or aromatic acids as compared to that of the corresponding original PLLA. In addition, more than 60 wt.% of the aliphatic acid-PLLAs was pyrolyzed, and aromatic acid-PLLAs degraded only about 10 wt.% for 150 min, although the original PLLA was pyrolyzed completely at 250°C for 7 min. The thermal stability of PLLA was controlled by the conjugation of aliphatic or aromatic acids into a chain end. These acid-PLLAs may be useful as materials with high thermal stability for various application fields. [ABSTRACT FROM AUTHOR]

In this review, liquid crystalline (LC) polyazomethines (PAZs) with aliphatic–aromatic moieties were investigated, taking into consideration their thermal, structural, optical and electrical properties. Liquid crystalline polymers with imine bonds in the main or side chains were analysed. The optical properties of LC polyazomethines, including UV–vis absorption, photoluminescence (PL) and thermoluminescence (TL), were studied, taking into consideration the polymer structure. Finally, the electrical properties, including the photovoltaic properties of a bulk heterojunction (BHJ) and monolayer devices based on LC polyazomethines, were investigated and compared with PAZ, which did not exhibit LC properties. In this review article, the recent research trend on LC polyazomethines is summarised. [ABSTRACT FROM AUTHOR]

A novel series of imine-diols (D-1, D-2, D-3, D-4, D-5,D-Ar) having inbuilt aliphatic and aromatic segments were prepared via two-step process involving nucleophilic substitution reaction between dibromoalkanes and 4-hydroxybenzaldehyde leading to the formation of dialdehydes and then its acid catalyzed reaction with 4-hydroxyaniline. Some new segmented poly(azomethine)esters (TPE-1, TPE-2, TPE-3, TPE-4, TPE-5, TPE-Ar, IPE-1, IPE-2, IPE-3, IPE-4, IPE-5, IPE-Ar) were synthesized by direct solution phase polycondensation of preformed monomer derivatives and organic diacid chlorides (terephthaloyl chloride (T) and isophthaloyl chlorides (I)) in THF under anhydrous/inert conditions. The monomers and polymers were characterized by viscosity, FTIR, NMR, UV/visible spectroscopy, solubility and XRD studies. The thermal behavior was studied by DSC and TGA. The esters prepared from 'T' were found thermally more stable than those prepared from 'I' due to the presence of p-substituted groups on benzene ring. The inherent viscosity of poly(azomethine)esters in N,N-dimethylacetamide (DMAC) was calculated and the range found was 0.008-0.10 dL/g. [ABSTRACT FROM AUTHOR]

ABSTRACT A series of aliphatic diacyl adipic dihydrazides (ADHs) with different alkyl moieties were synthesized by the reaction between adipic dihydrazide and acyl chloride. Then these ADHs were solution blended with PLA respectively and were evaluated as nucleating agents. Through the investigation of nonisothermal and isothermal crystallization, it was found that both the crystallization rate and the crystallinity of PLA could be enhanced by adding only 1 wt % of ADHs. Especially for ADH-Oc (ADH-Octyl), the crystallization rate of PLA increased about 4 times at 105°C. Optical morphology showed that and the size of PLA spherulites decreased and the nucleation density increased with the existence of ADH-Oc. Meanwhile, the crystal structure of PLA were not discerniblly affected after the addition of ADHs as found by wide-angle X-ray diffraction. Thus, this study suggested these ADHs compounds are simple and potential nucleating agents to enhance crystallization ability of PLA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42028. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes (MWNTs) functionalized with hyperbranched aliphatic polyamide (HAP) were prepared by polycondensation using 3-(2-aminoethylamino)propanoic acid methyl ester as monomer. The effects of HAP functionalized MWNTs (MWNT-HAP) on the properties of bismaleimide (BMI) resin were investigated. Nanocomposites based on BMI resin and different content of MWNTs were prepared. The properties of nanocomposites were characterized by TGA, DMA, flexural and impact tests. Because of the magnification of functional groups and the higher interfacial interaction between MWNT-HAP and BMI resin, the improvement of the mechanical and thermal properties of MWNT-HAP/BMI nanocomposites was more remarkable than nanocomposites containing pristine MWNTs. [ABSTRACT FROM AUTHOR]

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A new series of four different linear aliphatic ether linked aromatic bismaleimides (AEBMIs) were synthesized from the respective linear aliphatic ether-linked aromatic diamines and maleic anhydride. Further, the POSS-AEBMI nanocomposites were developed by Michael addition reaction of bismaleimide with varying mass percentages of octa(aminophenyl)silsesquioxane and were characterized by the fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Data from thermal studies revealed that the POSS-reinforced AEBMI nanocomposites possesses higher glass transition temperature ( Tg), thermal stability, limiting oxygen index, and lower dielectric constant when compare to that of neat AEBMI. X-ray diffraction and transmission electron microscopy analysis confirmed the molecular level dispersion of POSS in the AEBMI matrix. [ABSTRACT FROM AUTHOR]

Poly(butylenecyclohexanedicarboxylate/diglycolate) random copolymers(P(BCEmBDGn)) of various compositionswere synthesized and characterized from the molecular, thermal, structural,and mechanical point of view. Barrier properties to different gases(oxygen and carbon dioxide) were also evaluated. All the polymersshowed good thermal stability and appeared as semicrystalline materialsat room temperature. The main effect of copolymerization was a loweringin the crystallinity and a decrease of Tmwith respect to homopolymers. The dependence of Tmon composition for copolymers with high butylene cyclohexanedicarboxylateunit content was well described by Baur’s equation. X-ray diffraction(XRD) measurements indicated that two different crystalline phasesare present, depending on composition: copolymers with high BCE unitcontent were characterized by PBCE crystal phase, whereas those richin BDG counits crystallized in PBDG lattice. The samples displayeddifferent surface hydrophilicity: the water contact angle regularlydecreased with the increasing mol % of BDG. The mechanical propertieswere found strictly related to crystallinity degree (χc); the copolymers containing 60–75 mol % of BDG showed thelowest elastic modulus and the highest elongation at break. Lastly,the chemical composition of the copolymer strongly influenced permeabilityto CO2and O2. Moreover, the selectivity ratiosfor the examined samples increased with the increasing of BDG mol%, confirming the existence of a correlation between the permeabilityand the chemical composition. Almost all copolymers showed improvedbarrier properties with respect to polylactide films tested underthe same conditions. [ABSTRACT FROM AUTHOR]

Plant biomass-derived polymeric materials, including cellulosic polysaccharides, biodegradable aliphatic polyesters, and aromatic hydroxy acid polyesters, possess characteristic structures and molecular properties. For example, 100% optical purity and high molecular weight (>106) in microbial poly(hydroxyalkanoate)s and nanometer-size fibrous morphology of native cellulose are not attained in conventional petroleum-derived synthetic polymers. Utilizing these structural characteristics is crucial for expanding the applicable range of the biomass-derived polymers both for commodity and specialty purposes. However, the relation between polymer structure and material properties in the biomass-derived polymers has not yet been clarified in detail. In this paper, solubility, rheological and thermal properties of those plant-derived polymers are summarized from the viewpoint of molecular mobility and nano-structure. Furthermore, the biocompatibility of biodegradable polyester nanofibers is discussed as one of the promising applications of biomass-derived polymers. [ABSTRACT FROM AUTHOR]

In the field of aliphatic polyesters there is a great interest in building novel macromolecular structures that may effectively feature the required properties for specific applications. For this reason, it is extremely important to understand the correlations between chemical structure and final performance. Monomers based on the 1,4-cyclohexylene unit are interesting as they are potentially bio-based and rigid enough to improve glass transition and melting temperatures. The present paper describes the preparation of samples of poly(1,4-cyclohexylenedimethylene adipate), characterized by different cis/trans isomeric ratio of the cyclic units, the analysis of their thermal properties and the comparison with the properties of similar polymers such as poly(butylene adipate), poly(butylene-1,4-cyclohexanedicarboxylate) and poly(1,4-cyclohexylenedimethylene-1,4-cyclohexanedicarboxylate). The effect of the rigidity and of the stereochemistry of the 1,4-cyclohexylene unit on the thermal properties was analysed. Such an effect reaches its maximum level when the cyclic-containing monomers are the diacid or the diester and when the trans isomers predominate. Starting from such a result, the combination of specific cyclic building blocks with the correct cis/trans ratio makes it possible to build macromolecular structures with the required final properties. [ABSTRACT FROM AUTHOR]

Abstract: A novel class of aliphatic polyesters, and their derived copolyesters, have been developed. Beside their specific mechanical and thermal properties, the durability, in terms of biodegradability and photodurability, has been investigated. In particular, the polymers were submitted to natural and accelerated photo-ageing and an original methodology based on melt rheology has been applied to determine molecular changes upon UV weathering. Both scission and recombination reactions, which strongly compete as a function of the exposure time, were found to cause a strong evolution of the molecular structure. The results indicate that chemical structure and stereochemistry of the novel materials define the predominant process and the overall behaviour of the samples upon UV exposure. Moreover, the changes of the molecular structure, induced by UV irradiation, could have a significant role into the further biodegradability of the polymers. Therefore, while the relationships between structure and durability enable to design materials with desired well-adapted performances according to their final destination, the biodegradable character upon lifetime use is considered as really questionable and needs further studies. [Copyright &y& Elsevier]

Abstract: Linear aliphatic polyesters having pendant hydroxyl groups were successfully synthesised by polycondensation using scandium triflate as catalyst. A first set of samples was prepared starting with hexane-, octane-, decane-, and dodecanediol and l-malic acid as hydroxyl functional dicarboxylic acid, on the one hand, and succinic acid as non-functional analogue, on the other. A second set of samples was prepared starting with different hydroxytelechelic oligo(ε-caprolactone)s, synthesised in a ring opening polymerisation (ROP) initiated by hexanediol using the same catalyst, and reacted with l-malic acid or succinic acid, respectively. The successful reaction was confirmed by nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS). The thermal properties of both types of polyesters – with and without pendant hydroxyl groups – were analysed by differential scanning calorimetry (DSC). While all polyesters based on succinic acid are highly crystalline, for the polyesters based on l-malic acid the crystallinity depends on the concentration of pendant hydroxyl groups and on the microstructure. Hence, the influence of the hydroxyl group enables to tailor the crystallinity. [Copyright &y& Elsevier]

Chemical surface modification of nanofibrillated cellulose (NFC) was performed using a long aliphatic isocyanate chain. Different molar ratios of the coupling agents were tested, i.e., 1, 10, 30 equivalents with respect to hydroxyl groups of the NFC surface. FE-SEM analyses revealed that there were no changes in their morphology thus keeping nanofibril-like structure with about 30 nm of diameter. All these samples were characterized by different techniques (e.g., FTIR) to check the efficiency of the grafting. Hydrophobic NFC were achieved whatever the grafting agent ratio. The Degree of Substitution was determined by Elemental Analyses and the Degree of Substitution of the Surface was calculated thanks to X-ray Photoelectron Spectroscopy data. Combining these two techniques, the Internal Degree of Substitution was proposed for the first time. It indicates if the modification occurs also within NFC internal layers. Surface (contact angle), rheological (water suspension viscosity) and thermal properties (ThermoGravimetric Analysis) of grafted NFC do not follow the expected linear evolution of properties with the increase of molar ratio. X-Ray Diffraction analyses showed that the grafted aliphatic chains display crystalline waxy domains at some ratios. A model for aliphatic chain organization at the surface is proposed and clearly explained for the first time why a compromise in molar ratio is necessary to achieve best properties. [ABSTRACT FROM AUTHOR]

Cycloaliphatic epoxy resin containing hydroxyl group (DMTMP) was prepared by the transesterification between methyl-3,4-epoxycyclohexane carboxylate (MEC) and trimethylolpropane (TMP), which was then thermally cured with methylhexahydrophthalic anhydride (MHHPA). As comparison, a commercial available cycloaliphatic epoxy 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (ERL-4221) cured with the same curing agent was also investigated. The chemical structure was characterized by FT-IR and 1H-NMR. And the curing behavior and the thermal properties were studied by DSC and TGA. The DSC results showed that the DMTMP systems exhibited higher reactivity than the ERL-4221 systems due to the autocatalysis of hydroxyl group of DMTMP. While the glass temperature transitions (Tg s) of DMTMP systems were much lower than ERL-4221 systems, and the Tg s of DMTMP and ERL-4221 systems both reduced after introducing n-dodecyl trimethylammonium bromide (DTAB) as catalyst. The decomposition behavior from TGA shows that the DMTMP epoxy resins exhibited a relative slow weight decreasing tendency in comparison with ERL-4221 epoxy resins, but initial degradation temperatures of DMTMP systems were lower than ERL-4221 systems. [ABSTRACT FROM PUBLISHER]

Polylactide (PLA) is a bio-based, biodegradable polymer, which is derived from lactic acid and has numerous potential applications, some of which are limited by its moisture barrier and thermal properties. Prior studies have been inconsistent about how moisture sorption in PLA varies with crystallinity and molecular weight. This research is a systematic study of how moisture sorption in PLA depends on molecular weight and aliphatic content via end-group modification. PLA with varying aliphatic content was synthesized by ring-opening polymerization of -lactide initiated with different long-chain aliphatic alcohols. The terminating end groups were also modified from hydroxyl to acetoxy to eliminate hydrophilic end groups. Molecular weight was controlled by varying the ratio of -lactide monomer to alcohol initiator, and triethylaluminum was used as the catalyst for precise control over molecular weight. The molecular weight and end-group compositions were verified by gel permeation chromatography and nuclear magnetic resonance. Moisture sorption of the modified PLA samples was measured with a quartz crystal microbalance. Quartz crystal microbalance experiments revealed that both molecular weight and aliphatic content contributed to the sorption properties of PLA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Aliphatic-aromatic biodegradable random copolyester, poly (butylene sebacate-co-butylene isophthalate) (PBSeI) was synthesized by a two step direct melt polycondensation method. This copolyester was characterized by solubility studies, viscosity measurements, infrared, ¹H-NMR, 13C-NMR and thermal data. However, to be a real alternative to classical synthetic polymers and find applications, the thermal properties of biodegradable polymers have to be improved. Synthesis of nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, is an interesting way to create polymers with characteristic properties. In the present study, the nano-biocomposites were synthesized by dispersing different weight percentages (1, 3 and 5%) of organo-modified montmorillonite clay (OMMT) into the biodegradable polyester matrix by the solvent intercalation method. Structural characterization and thermal analysis were carried out to better understand, the relationship between the structuring of the nanofillers and the properties of nano-biocomposites. The X-ray diffraction patterns obtained for the systems confirmed the nanodispersion of the OMMT-clay in the polyester networks. The scanning electron microscopy and high resolution transmission electron microscopy analyses showed that there was no phase separation between the two components which confirmed the compatibility of polyester with the organo-modified clay system. The results show that clay incorporation improved the thermal properties of PBSeI due to the exfoliated structure of the nanocomposites formed, and thus may increase the applicability of this biodegradable polymer in different fields. [ABSTRACT FROM AUTHOR]

Abstract: New type of aromatic–aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T g ) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability. [Copyright &y& Elsevier]

Abstract: This study deals with preparation and characterization of polymethylmetracrylate (PMMA) microcapsules containing n-octacosane as phase change material for thermal energy storage. The surface morphology, particle size and particle size distribution (PSD) were studied by scanning electron microscopy (SEM). The chemical characterization of PMMA/octacosane microcapsules was made by FT-IR spectroscopy method. Thermal properties and thermal stability of microencapsulated octacosane were determined using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The melting and freezing temperatures and the latent heats of the microencapsulated octacosane as PCM were measured as 50.6 and 53.2°C, 86.4 and −88.5J/g, respectively, by DSC analysis. TGA analysis indicated that the microencapsulated octacosane degrade in two steps and had good chemical stability. Thermal cycling test shows that the microcapsules have good thermal reliability with respect to the accelerated thermal cycling. Based on the results, it can be considered that the microencapsulated octacosane have good energy storage potential. [Copyright &y& Elsevier]

Abstract: New thermoplastic poly(carbonate-urethane) elastomers (TPCUs) were prepared by a one-step melt polymerization from 20–80mol% poly(hexane-1,6-diyl carbonate) diol of as a soft segment, hexane-1,6-diyl diisocyanate and 2,2′-[methylenebis(1,4-phenylenemethylenethio)]diethanol, 3,3′-[methylenebis(1,4-phenylenemethylenethio)]-dipropan-1-ol or 6,6′-[methylenebis(1,4-phenylenemethylenethio)]dihexan-1-ol (H) as new chain extenders at the NCO/OH molar ratio of 1 in the presence of dibutyltin dilaurate as a catalyst. The structures of the TPCUs were examined by FTIR spectroscopy, X-ray diffraction analysis, scanning electron microscopy and atomic force microscopy (AFM). The TPCUs were also characterized by physicochemical, thermal (by differential scanning calorimetry (DSC) and thermogravimetry) and tensile properties as well as Shore A/D hardness. The resulting TPCUs were colorless polymers, showing ordered structures including semicrystalline, with the highest ability to crystallize exhibited by the polymers derived from diol H. The polymers with the soft-segment content of 40–80mol% (56.4–25.7wt% of hard segments) exhibited a microphase separation shown by DSC and AFM. The TPCUs showed tensile strength in the range of 8.8–23.3MPa and elongation at break in the range of 240–670%. [Copyright &y& Elsevier]

Abstract: Surface treated montmorillonite was used to prepare nanocomposites with aromatic–aliphatic polyamide by solution intercalation technique. The polyamide chains were produced through polycondensation of 4-aminophenyl sulfone with sebacoyl chloride in dimethyl acetamide. Compatibility between the polymer and organoclay was achieved through carbonyl chloride end-capped amide chains prepared by adding extra sebacoyl chloride near the end of polymerization reaction. The nanocomposites morphology and clay dispersion were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Delaminated and intercalated morphologies were observed for different loading of organoclay. Tensile strength and modulus improved for nanocomposites with optimum organoclay content (10-wt.%). Thermal stability and glass transition temperature of nanocomposites increased relative to pristine polyamide with augmenting organoclay content. Water uptake of these materials decreased as compared to the neat polyamide indicating reduced permeability. [Copyright &y& Elsevier]

Abstract: In this study, we prepared cross-linked aliphatic polyester derived from branched poly(ɛ-caprolactone (abbreviated as CL)-co-d,l-lactide (abbreviated as LA)) macromonomers with different CL and LA compositions and investigated the effect of thermal properties on their degradation. According to the degradation study, the weight loss became larger with increasing LA composition in poly(CL-co-LA). The introduction of LA units that can degrade easily disturbed the crystallinity of the PCL segments; as result, the hydrolysis became accelerated. Also, we studied the temperature dependency of degradation of a series of cross-linked poly(CL-co-LA) materials with different melting points. We found that the degradation of these materials related closely to the crystallinity, which could be controlled by the composition of CL and LA. [Copyright &y& Elsevier]

Some poly(alkylene dicarboxylate)s, derived from ethanediol or 1,4-butanediol and different diacids, have been synthesized and analyzed by DSC to determine the correlations existing between the thermal properties and the length of the aliphatic chain. The polymers show crystallization and melting temperatures and enthalpies which increase as the polymethylene segments lengthen, due to the formation of more stable crystals. The samples derived from ethanediol are peculiar; they show reorganization processes during the melting and the melting temperatures are notably higher with respect to those of the other polyesters. This behavior is discussed. Isothermal analysis highlights that poly(alkylene dicarboxylate)s are fast crystallizing polymers. The Avrami analysis suggests a crystallization mechanism characterized by heterogeneous nucleation and three dimensional growth; secondary crystallizations is present only in the samples characterized by short--(CH2)-sequences, due to the reorganization of less perfect crystalline forms. A comparative study between the crystallization rates as a function of the undercooling is reported. [ABSTRACT FROM AUTHOR]

Abstract: Poly(butylene succinate-co-butylene adipate) was obtained from 1,4-butanediol and dimethyl esters of succinic and adipic acids through a two step process of transesterification and polycondensation. High molecular weight polyesters were synthesized using hexamethylene diisocyanate as chain extender. The effect of chain extension reaction time and chain extender content on polyester molecular weight, thermal and mechanical properties, was investigated. Polyesters were characterized by means of nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), viscosity measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD) and mechanical property measurements. Chain extension reaction had as a result the significant increase of polyester molecular weight leading to increased tensile strength. Polyester crystallinity, as calculated from XRD and DSC analysis, and melting temperature decreased upon chain extension, while glass transition temperature increased. Polyester biodegradation was investigated by soil burial and enzymatic hydrolysis using the enzyme Pseudomonas fluorescens cholesterol esterase. It appears that biodegradation was affected by polyester crystallinity, rather than by its molecular weight. [Copyright &y& Elsevier]

Abstract: A series of aliphatic homopolyesters and copolyesters was prepared from 1,4 butanediol and dimethylesters of succinic and adipic acids through a two-step process of transesterification and polycondensation. The synthesized polyesters were characterized by means of nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), viscosity measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and mechanical property measurements. The homopolymer poly(butylene succinate) exhibited the highest tensile strength, which decreased with increasing adipate unit content, passed through a minimum at copolyester composition close to equimolarity and then increased towards the value of poly(butylene adipate). It is interesting to note that in contrast to tensile strength, the elongation at break increased for adipate unit content of 20–40mol%. The biodegradation of the polymers was investigated by soil burial and enzymatic hydrolysis using three enzymes, Candida cylindracea lipase, Rhizopus delemar lipase, and Pseudomonas fluorescens cholesterol esterase. It appears that the key factor affecting material degradation was its crystallinity. [Copyright &y& Elsevier]

Abstract: High molecular weight polybenzoxazine precursors have been synthesized from aromatic or aliphatic diamine and bisphenol-A with paraformaldehyde. The precursors were obtained as soluble white powder. Molecular weight was estimated from the size exclusion chromatography to be several thousands. The structure of the precursors was confirmed by IR, 1H NMR and elemental analysis, indicating the presence of cyclic benzoxazine structure. The ratio of the ring-closed benzoxazine structure and the ring-opened structure in the high molecular weight precursor was estimated from 1H NMR spectrum and also from the exotherm of DSC, showing that the ratio of the ring-closed benzoxazine structure was 77–98%. The precursor solution was cast on glass plate, giving transparent and self-standing precursor films, which was thermally cured up to 240°C to give brown transparent polybenzoxazine films. The toughness of the crosslinked polybenzoxazine films from the high molecular weight precursors was greatly enhanced compared with the cured film from the typical low molecular weight monomer. Tensile measurement of the polybenzoxazine films revealed that polybenzoxazine from aromatic diamine exhibited the highest strength and modulus. While, polybenzoxazine from longer aliphatic diamine had higher elongation at break. The viscoelastic analyses showed that the glass transition temperature of the polybenzoxazines derived from the high molecular weight precursors were as high as 238–260°C. Additionally, these novel polybenzoxazine thermosets showed excellent thermal stability. [Copyright &y& Elsevier]

Abstract: A diepoxide compound derived from trehalose, 2,3-anhyrdo-4,6-O-benzylidene-α-d-allopyranosyl 2,3-anhydro-4,6-O-benzylidene-α-d-allopyranoside, was synthesized and reacted with aliphatic diamines. The ring-opening reaction was carried out in 1-methyl-2-pyrrolidone (NMP) in the presence of triphenylphosphine (TPP), tris(4-methoxyphenyl)phosphine (TMPP) or 2-ehtyl-4-methylimidazole (2E4MIm), as a base catalyst. The reaction of the diepoxide compound with 1,6-diaminohexane yielded a soluble polymer with weight average molecular weight (Mw)∼6300 (GPC) and did not yield insoluble matter. The reaction of the diepoxide compound with N,N′-dimethyl-1,6-diaminohexane yielded a polymer with Mw∼6500 (GPC). The product was soluble in many organic solvents such as NMP, N,N-dimethylformamide (DMF), tetrahydrofuran (THF), acetone, toluene and ethyl acetate. Thermal analysis with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed that the glass transition temperature of the polymer was ∼100°C and that the degradation temperature was ∼320°C. [Copyright &y& Elsevier]

Biodegradable aliphatic poly(butylene succinate-co-ethylene succinate) PBES and poly(butylene succinate-co-diethylene succinate) (PBDEGS) were synthesized from succinic acid and 1,4-butanediol/diethylene glycol through a direct polycondensation with titanium tetraisoproxide (TTP) and diphenylphosphinic acid (DPPA) as the co-catalysts. GPC and NMR results indicated molecular weight Mn higher than 5.0×104 and 6.5×104 for the PBES and PBDEGS copolymers respectively, with ES/DEGS populations spanning the whole comonomer composition, and the BS and ES sequence distributions were found to be in close agreement with the random model. DSC analyses revealed that thermal and crystallization behaviour strongly depended on the corresponding comonomer composition for the PBES and PBDEGS copolymers, and that PDEGS was an amorphous poly(ester-ether). For thermal stability, TGA results indicated that thermal stabilities of the prepared PBDEGS significantly decreased with increasing the DEGS unit composition, while there was no remarked decrease detected for those of the PBES copolyesters. In addition, measurements of mechanical properties showed that incorporation of a small amount of ether groups into the DEGS unit could more remarkably improve the elongation behaviour of the semi-crystalline copolymer than that of the ES unit, and much larger elongation rates were exhibited for the copolymer samples bearing 47, 78 mol% ES and 8, 28 mol% DEGS. [Copyright &y& Elsevier]

This article discusses a study which investigated the thermal properties of aliphatic polyester oligomers as functions of the degree of polymerization. In the past, biodegradable alipathic polyesters that comprised of alkanediol and dicarboxylic acid have received attention because its preparation is simple and they are much cheaper than other biodegradable polymers. Biodegradability is the most significant property of alipathic polyesters. Generally, polymers are polydisperse materials because the formation of polymer follows a random process.

The present paper describes the synthesis of novel bio-based poly(butylene 1,4-cyclohexane dicarboxylate)-containing random copolymers for sustainable and flexible packaging applications. On one side, the linear butylene moiety has been substituted by glycol subunits with alkyl pendant groups of different length. On the other side, copolymers with different cis/trans isomer ratio of cyclohexane rings have been synthesized. The prepared samples were subjected to molecular, thermal, diffractometric, and mechanical characterization. The barrier performances to O2, CO2, and N2 gases were also evaluated. The presence of side alkyl groups did not alter the thermal stability, whereas it significantly influences the formation of ordered phases that deeply affect the functional properties, mainly in terms of mechanical response and barrier performance. In particular, the final materials present higher flexibility and significantly improved barrier properties with respect to the homopolymer and most polymers widely employed for flexible packaging. The improvement due to copolymerization was more pronounced in the case of higher co-unit-containing copolymers and for the samples with cyclohexane rings in the trans conformation. [ABSTRACT FROM AUTHOR]