Ethylene Succinate Research Articles

Analysis of the degree of crystallinity in interpenetrating spherulites of poly(ethylene succinate) and poly(ethylene oxide) blends using pulsed NMR

The degree of crystallinity (φ) in interpenetrating spherulites, whereby spherulites of one component continue to grow inside those of the other component, was examined for the blends of poly(ethylene succinate) (PES) and poly(ethylene oxide) (PEO) using pulsed nuclear magnetic resonance. The crystallization temperature influenced the time ranges of the primary crystallization. The value of φ for PES and PEO exhibited different dependence on the blend composition. These results are discussed on the basis of the change in temperature at which the molecular transport is frozen with the blend composition.

Conformational characteristics and configurational properties of poly(ethylene succinate) and poly(butylene succinate) and structure–property–function relationships of representative biodegradable polyesters

Conformational characteristics and configurational properties of synthetic biodegradable polyesters, poly(ethylene succinate) and poly(butylene succinate), have been investigated by NMR experiments and molecular orbital calculations on their model compounds and the rotational isomeric state calculations for the two aliphatic polyesters. The results have been related to their crystal structures and thermal properties and compared with those obtained previously for poly((R)-3-hydroxybutyrate) and poly(lactic acid) to elucidate structure–property relationships of the representative biodegradable polyesters. In addition, selective affinities to degradative enzymes of the four polyesters have been satisfactorily explained in terms of their conformational characteristics and interactions with the depolymerases.

Composition dependence of physical properties of biodegradable poly(ethylene succinate) urethane ionenes

To obtain an excellent comprehensive performance of poly(ethylene succinate) (PES), we have synthesized a series of poly(ethylene succinate) (PES) urethane ionenes (PESUIs) with various content of urethane ionic group by the chain extension reaction of dihydroxyl-terminated poly(ethylene succinate) and diethanolamine hydrochloride with hexamethylene diisocyanate as a chain extender, and we systematically investigated the composition dependence of the physico-chemical properties of PESUI through a series of characteristic techniques. The results of thermal and crystallization behaviors suggest that the incorporation of urethane ionic group slightly affects the glass transition temperature, melting temperature, and thermal stability, and significantly accelerates the crystallization rate of PES without changing the crystallization mechanism. The fastest crystallization rate was reached with the incorporation of 4 mol% urethane ionic groups. Spherulitic morphology observation indicates that nucleation density significantly increased, while spherulitic growth rate gradually decreased with increase in urethane ionic group content. Both complex viscosity and storage modulus initially increased and then decreased with increase in urethane ionic group content, and their maximum values were observed for the sample with 4 mol% of urethane ionic group. Mechanical properties slightly varied with urethane ionic group content.

Crystallization Kinetics and Morphology of Biodegradable Poly(ethylene succinate)/Octavinyl-Polyhedral Oligomeric Silsesquioxanes Nanocomposites

One of the main drawbacks of biodegradable poly(ethylene succinate) (PES) is its slow crystallization rate. We prepared three nanocomposite samples in the present work by incorporating different small amounts of octavinyl-polyhedral oligomeric silsesquioxanes (ovi-POSS) into the PES matrix. The morphology and dispersion of ovi-POSS were first studied with a scanning electron microscope in the PES matrix. The nanofiller showed a nice dispersion throughout the polymer matrix with a regular structure, indicating the crystalline feature. The influences of different amounts of ovi-POSS on the nonisothermal and isothermal crystallization behaviors, spherulitic morphologies, and crystal structures of the nanocomposites were extensively investigated with several techniques. Ovi-POSS obviously enhanced the crystallization behaviors of PES as an efficient nucleating agent in the nanocomposites; moreover, the nanocomposites and neat PES had the same crystal structures and crystallization mechanisms.

Crystallization and melting behavior of poly (ethylene succinate) in presence of graphene nanoplatelets

• Poly (ethylene succinate)/graphene nanocomposites were characterized in this work. • Dynamic and isothermal crystallization rates were enhanced upon graphene addition. • Overall crystallinity and melting remained almost unchanged in presence of graphene. • Graphene changed crystal perfection and its effect was found concentration-dependent. In this study, poly (ethylene succinate)/graphene nanoplatelets composites were prepared via solution casting method in different compositions and analyzed via differential scanning calorimetry. Crystallization and melting characteristics in both dynamic (non-isothermal) and isothermal modes were investigated at various cooling rates and isothermal temperatures. It was confirmed that graphene, while being incompatible with the matrix polymer, could act as nucleating agent so that hot (melt) crystallization rates, intensities, and positions were increased in the dynamic mode. However, the overall crystallinity remained almost unchanged. Cold crystallization was also decreased to lower temperatures on graphene addition; however its enthalpy was also reduced. Similar findings were observed for the isothermal mode, but to a lesser extent. The presence of graphene changed the perfection of crystals as their thermodynamic stability against heating and recrystallization behavior varied.

Effects of melt annealing on the miscibility and crystallization of poly(butylene succinate)/poly(ethylene succinate) blends

We discuss the enhancement in miscibility of crystalline/crystalline blends of poly(butylene succinate) and poly(ethylene succinate) (PBS/PES) by simple melt annealing, their crystallization process and the formation of characteristic phase-separated structure. The immiscible PBS/PES blends changed into miscible blends when annealed at 150 °C. Gel permeation chromatography and differential scanning calorimetry measurements suggested that the annealing process caused transesterification between the PBS and PES, resulting in the formation of PBS–PES copolyesters. The unannealed blends exhibited phase-separated melts with constituents that crystallized separately. A PBS-rich layer was formed between the PES-rich phase and the glass substrate from the phase-separated melts of the unannealed blends. In contrast, the miscible annealed blends crystallized by two distinct processes. The first process, successive crystallization, involved PBS spherulite formation in the homogeneous melt and PES spherulite nucleation inside the PBS spherulites. The second process involved the simultaneous nucleation of both components from the melt and penetrating growth of the PES spherulites into the PBS spherulites.

Diversification of spherulite patterns in poly(ethylene succinate) crystallized with strongly interacting poly(4-vinyl phenol)

Poly(ethylene succinate) (PESu) blend with amorphous poly(vinyl phenol) (PVPh) in thin films were investigated on the crystalline spherulites patterns and crystalline lamellar arrangements by using polarized optical microscopic (POM) and atomic-force microscopy (AFM). A total of nine different types of crystalline morphology were identified in the PESu/PVPh blend with amorphous contents from 10 to 35 wt.% and T c = 40–70 °C in ultra-thin film thickness. Multiple types of PESu crystalline morphology at the same crystallization temperature (T c ) are never seen in neat PESu, but only occur in PESu/PVPh blend with amorphous PVPh higher than 20 wt.%. Crystalline morphology diagrams are summarized to display various spherulite types in the PESu/PVPh blend confined in thin films as a function of crystallization temperature and blend composition. Crystallization temperature, thickness/space confinement, and presence of interacting amorphous PVPh are the main factors for multiple types of spherulites in the blends, partly due to strong interactions via hydrogen bonding between PESu and PVPh and likely extra nucleation capacity from the diffusion interfaces.

Dendritic Morphology Composed of Stacked Single Crystals in Poly(ethylene succinate) Melt-Crystallized with Poly(p-vinyl phenol)

Dendritic morphology with stacked single crystals of poly(ethylene succinate) (PESu) melt-crystallized in the presence of amorphous poly(p-vinyl phenol) (PVPh) were observed and analyzed using optical microscopy (OM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). At higher temperatures, the fluffy dendritic morphology was a transition in melt-crystallized PESu/PVPh from originally compact crystals at lower crystallization temperature. The addition of amorphous and strongly interacting PVPh polymer, confinement in thin films, and high crystallization temperature were considered as the main factors of the crystals transition from compact crystals to dendritic crystals. Single crystals of PESu were proven by AFM in the PESu/PVPh blend especially when confined in films of above 500 nm, melt-crystallized at Tc = 70 °C or above. The electron diffraction pattern of TEM result further confirmed the formation of PESu single crystals. The combination of thin film thickness, high crystallization temperature, and strong interaction between two polymers were believed to be the main factors for melt-crystallized PESu single crystals. In the single crystals with spiral arrays, the PESu chains, though achiral, tend to exhibit paired-up crystal entities resembling “identical twins” but with opposite helical directions. The single-layer thickness is almost equal between the paired-up lozenge lamellae screwing clockwise or counterclockwise. The PESu single crystals in PESu/PVPh blend were melt-grown, and electron diffraction patterns proven in this study are in agreement with the literature for neat PESu single crystals grown in dilute solutions.

Influence of Thermally Reduced Graphene Low-Loadings on the Crystallization Behavior and Morphology of Biodegradable Poly(ethylene succinate)

Through a solution and coagulation method, biodegradable poly(ethylene succinate) (PES) and thermally reduced graphene (TRG) nanocomposites were prepared at low TRG loadings. The nonisothermal melt crystallization peak temperature values and overall isothermal melt crystallization rates are greater in the nanocomposites than in neat PES, indicative of a nucleating agent effect of TRG; however, the crystallization mechanism of PES remains unchanged in the nanocomposites, regardless of TRG loading and crystallization temperature. The nonisothermal and melt crystallization processes of the nanocomposites are found to vary with the TRG loading, exhibiting a maximum at 0.25 wt % TRG loading. The incorporation of a small amount of TRG shows little influence on the spherulitic growth rates but obviously affects the spherulites nucleation density values of the nanocomposites. TRG does not modify the crystal structure of PES in the nanocomposites.

Stress induced lamellar thickening in poly(ethylene succinate)

The crystalline structure evolution of poly(ethylene succinate) during tensile deformation was investigated by in-situ synchrotron X-ray scattering. Crystal phase transition from α to β form was confirmed to be fully reversible upon stress loading and unloading. An increase of long period was observed during the α–β crystal transition, which was attributed to the increase of both amorphous layer thickness and crystalline layer thickness (lamellar thickness). The crystalline layer thickness was scaled with the fraction of β crystal, and the change of which was in well agreement with the difference in the repeating length along the crystallographic c axis. Both the crystalline layer thickness and the amorphous layer thickness were fully recoverable. A possible molecular model was proposed to visualize the mechanism for the crystal transition and lamellar thickening.

Poly(ethylene succinate)-b-poly(butylene succinate) Multiblock Copolyesters: The Effects of Block Length and Composition on Physical Properties

Poly(ethylene succinate)-b-poly(butylene succinate) (PES-b-PBS) multiblock copolymers with different block lengths and compositions were synthesized, and their chemical structure, molecular weights, and polydispersity index of the copolymers were characterized by 1H NMR and GPC, respectively. The miscibility and crystallization of PES and PBS blocks in the copolymers were investigated by DSC. The results suggested that PES and PBS blocks are miscible in copolymers with shorter block lengths, while they are partially miscible in those with longer block lengths. The crystallization of PBS blocks were depressed with an increase in PES content due to the diluent effect, and that of PES blocks was largely restricted when its content was less than the PBS block, while that was improved when its content was more than that of the PBS block due to the nucleation effect of previously crystallized PBS. The results of tensile test suggest that all the copolymers showed excellent mechanical property.

Poly(ethylene succinate)/single-walled carbon nanotube composites: a study on crystallization

An investigation on the crystallization of composites based on poly(ethylene succinate) and unmodified single-walled carbon nanotube was made in this report. Both isothermal and non-isothermal modes were studied along with subsequent melting behavior using differential scanning calorimetry. Crystal morphology was then explored using X-ray scattering and infrared spectroscopy. It was observed during isothermal crystallization that carbon nanotube (CNT) could contribute to the crystallization rate through heterogeneous nucleation. Furthermore, nanotubes enhanced the crystallinity within low and high undercooling rather than medium undercooling. Similar findings were obtained in non-isothermal crystallization mode. At lower cooling rates, the crystallization rate was more strongly influenced by the nanotubes, while at higher cooling rates the crystallinity was affected to the greater extent. The onset of the cold crystallization of polymer remained unaffected in presence of the nanotube, while its extent was reduced. X-ray diffraction together with infrared spectroscopy found that the polymer crystalline morphology was of α type, and no transition from α to β occurred in presence of the CNT.

Biodegradable poly(ethylene succinate) nanocomposites. Effect of filler type on thermal behaviour and crystallization kinetics

Nanocomposites based on poly(ethylene succinate) (PES) containing different types of inorganic nanofillers, including graphene oxide, modified graphene oxide, multi-walled carbon nanotubes and silver nanoparticles at a concentration of 2.5 wt% were prepared by solution casting. Good dispersion of the nanomaterial in the polymer matrix was verified with SEM microphotographs. WAXD patterns showed no change in crystal type of PESu in the nanocomposites. Crystallization was studied with DSC and involved non-isothermal melt and cold crystallization, as well as isothermal crystallization from the melt. All nanocomposites presented faster crystallization compared to pristine polymer with MWCNT resulting in the faster crystallization rate. Avrami's method was applied to simulate crystallization kinetic data and a good fitting was observed for the whole relative degree of crystallinity range in pristine PESu and all nanocomposites, except those with MWCNT, where it failed at high conversions. The activation energy of non-isothermal crystallization was calculated using the isoconversional model of Friedman and the nanocomposites with MWCNT exhibited higher values compared to other materials, though corresponding to higher (melt crystallization) or lower (cold crystallization) temperatures. Moreover, MWCNT was found also to have the higher nucleation activity. The Lauritzen–Hoffman analysis was also applied to analyse isothermal crystallization data and the generated morphology on isothermal crystallization from the melt was studied by Polarized Light Microscopy. The size of spherulites decreased as the polymer crystallization was nucleated by the nanoparticles and also the texture was affected.

Graphene‐reinforced biodegradable poly(ethylene succinate) nanocomposites prepared by in situ polymerization

ABSTRACTIn this study, poly(ethylene succinate)(PES)/graphene nanocomposites were facilely prepared by in situ melt polycondensation of succinic acid and ethylene glycol in which contained well dispersed graphene oxide (GO). Fourier transform infrared (FTIR), GPC, TGA, and XRD were used to characterize the composites. The FTIR spectra and TGA measurement confirmed that PES chains had been successfully grafted onto GO sheets along with the thermal reduction of GO to graphene during the polymerization. GPC results indicated that increasing amounts of graphene caused a slight decrease in number average molecular weight of PES matrix when polymerization time was kept constant. The content of grafted PES chains on graphene sheets was also determined by TGA and was to be about 60%, which made the graphene sheets homogeneously dispersed in the PES matrix, as demonstrated by SEM and XRD investigations. Furthermore, the incorporation of thermally reduced graphene improved the thermal stability and mechanical properties of the composites significantly. With the addition of 0.5 wt % graphene, onset decomposition temperature of the composite was increased by 12°C, and a 45% improvement in tensile strength and 60% in elongation at break were also achieved. The enhanced performance of the composites is mainly attributed to the uniform dispersion of graphene in the polymer matrix and the improved interfacial interactions between both components. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3212–3220, 2013

Nano-HA Preparation and its Effects on Mechanical Properties of nHA/PLLA/PES Composite Biomaterials

Nanocrystals hydroxyapatite (nHA) was synthesized and modified chemically, and nanocrystals hydroxyapatite / poly(L-lactide)/poly(ethylene succinate)(nHA/PLLA/PES) composite was prepared by melt-blending using nHA, PLLA and PES as reactants in a stainless steel chamber. The obtained nHA was of high purity and high crystallinity as well, its mean sizes measured from TEM observations were 65±35nm (long axis) and 40±10nm (short axis), and are close to the endosteal needle hydroxyapatite crystals size ((15 ~ 20) nm×60 nm) in the human body. The mechanical properties of nHA/ PLLA/PES blends were determined by bending and tensile tests and the effects of nHA content on the mechanical properties of nHA/PLLA/PES blends were investigated. The blending modulus and tensile modulus increase with the nHA (0,5,10,15and 20 wt.%) content increase, while blending strength increases up to HA mass fraction of 10% and after that decreases. SEM images revealed that the surface changed from rough to smooth with increasing nHA content, especially with nHA content higher than 20%, which implied the failure mechanism of the material changes from ductile to brittle.

Morphology and interpenetrated growth of spherulites in miscible poly(ethylene succinate)/poly(ethylene oxide) blends

Morphology development and growth process of spherulites in miscible poly(ethylene succinate)/poly(ethylene oxide) blends are studied by means of polarizing optical microscopy and atom force microscopy in this paper. Thin films with different film thicknesses were used to follow the growth processes of spherulites and dendrites. It is shown that, when one component spherulite grows, the other component in the melt is always excluded from the spherulite. The excluded component may reenter into the spherulite through diffusion depending on amorphous volume fraction of spherulite and segmental mobility of molecules, which leads to the occurrence of interpenetrated growth. This mechanism was analyzed in detail in this paper.

Crystallization Kinetics and Morphology of Novel Biodegradable Poly(hexamethylene succinate-co-3 mol % ethylene succinate) with Low and High Molecular Weights

The crystal structure, basic thermal behavior, nonisothermal melt crystallization behavior, overall isothermal melt crystallization kinetics, and spherulitic morphology of novel biodegradable poly(hexamethylene succinate-co-3 mol % ethylene succinate) P(HS-co-3 mol %ES) with low and high molecular weights, i.e., PHES12k and PHES58k were investigated. Both PHES12k and PHES58k have the same crystal structure as neat poly(hexamethylene succinate). The glass-transition temperatures are almost the same for both PHES12k and PHES58k. The melt point temperatures and crystallization peak temperatures are higher in PHES12k than in PHES58k; however, the equilibrium melting point temperatures are lower in PHES12k than in PHES58k. With an increase in crystallization temperature, the overall isothermal melt crystallization rates decrease gradually for both PHES12k and PHES58k; moreover, at the same crystallization temperature, PHES12k crystallizes faster than PHES58k. The spherulitic growth rates are faster in PHES12k than in PHES58k, while the nucleation densityof the spherulites is lower in PHES12k than in PHES58k.

Effect of Low Octavinyl-Polyhedral Oligomeric Silsesquioxanes Loading on the Crystallization Kinetics and Morphology of Biodegradable Poly(ethylene succinate-co-5.1 mol % ethylene adipate) as an Efficient Nucleating Agent

In this work, a biodegradable polymer composite was prepared by mixing poly(ethylene succinate-co-5.1 mol % ethylene adipate) (PESA) and octavinyl-polyhedral oligomeric silsesquioxanes (ovi-POSS) at a very low ovi-POSS loading. It is found that a fine dispersion of ovi-POSS has been achieved in the PESA matrix. The effects of ovi-POSS on the nonisothermal melt and cold crystallization behaviors, overall isothermal melt crystallization kinetics, spherulitic morphology, and crystal structure of PESA in the composite were studied in detail with various techniques. Relative to neat PESA, both the nonisothermal melt and cold crystallization behaviors and isothermal melt crystallization kinetics of PESA have been enhanced significantly in the composite. Ovi-POSS is an efficient nucleating agent for the crystallization of PESA, because the nucleation density of PESA spherulites is apparently higher in the composite than in neat PESA; however, the crystallization mechanism and crystal structure of PESA remain unchanged in the composite.

Miscibility Behavior of Poly Ethylene Glycol or Poly Ethylene Succinate/Chlorinated Poly Vinyl Chloride Blends Studied by Dielectric Relaxation Spectroscopy

The miscibility of chlorinated poly vinyl chloride (CPVC) and poly ethylene glycol (PEG) or poly ethylene succinate (PES) had been investigated using dielectric relaxation spectroscopy (DRS) over frequency and temperature ranges; 10 kHz - 4 MHz and 300 - 450 K, respectively. Three relaxation processes namely ρ-, α’-, and α-relaxation processes were observed for tan(δ) and the electric modulus M" of pure components and blends. The first one was attributed to the space charge polarization or the Maxwell-Wagner polarization. The second one was related to the amorphous regions located between the lamellar crystal stacks. The third one was due to the micro-Brownian motion of CPVC main chains. This process was found to be dependent in respect of temperature and frequency. The molecular dynamics of α-relaxation process were influenced by blending, i.e., the dielectric strength (De), the peak broadness, and the peak maximum of tan(δ) were found to be compositional dependent. Electric modulus analysis reveals that there is a role of electrode polarization for the dielectric relaxation.

Covalently bonded poly(ethylene succinate)/SiO2 nanocomposites prepared by in situ polymerisation

Poly(ethylene succinate)/SiO2 nanocomposites were prepared in situ with different SiO2 contents. 13C NMR spectra revealed that the hydroxyl end groups of poly(ethylene succinate) could form covalent bonds with the surface silanol groups of SiO2. These interactions had a significant positive effect on the molecular weight and mechanical properties of the nanocomposites. TEM revealed homogeneous dispersion of the nanoparticles, with some aggregates appearing at higher concentrations. Crystallization under isothermal and non-isothermal conditions was extensively studied. The nanoparticles acted as a nucleating agent and the nucleation activity was calculated for non-isothermal melt- and cold-crystallization. Activation energy of non-isothermal cold-crystallization was estimated using the isoconversional method of Friedman. Moreover, crystallization kinetics were analysed and spherulitic morphology also examined. The enzymatic hydrolysis rate of the nanocomposites was slowed down by the incorporation of the inorganic nanoparticles, attributed to the smaller available biodegradable surface and the existence of branched and crosslinked macromolecules.