Search

The recycled low density polyethylene (LDPE), recycled high density polyethylene (HDPE) and recycled polyethylene terephthalate G copolyester (PETG) as post-processed plastic wastes from extrusion blow molding process were modified with blending process to improve the properties of those plastic wastes and decrease the amount of plastic wastes in the plastic processing plants. The recycled PETG was blended with recycled LDPE and recycled HDPE in various concentration from 0 wt% to 100 wt% in increments of 10 wt% as referred to LDPE/PETG blends and HDPE/PETG blends respectively prepared by co-twin screw extruder. The addition of PETG in the blending of LDPE and HDPE improved the mechanical properties and MFI of those polymer blends but decreased thermal stability, storage modulus, loss modulus and complex viscosity as compared to those of neat LDPE and neat HDPE. LDPE/PETG blends illustrated better impact properties and flexibility than those of HDPE/PETG blends.

High-performance and eco-friendly nonwoven-nanofiber filters comprising renewably sourced bio-based polyesters were fabricated by electrospinning (ES). Typical commercial nonwoven filters are thick, with uneven fiber distributions and low recovery. Bio-based polymers made of raw plant materials have soft textures. Over 75% of the polyester used herein was sourced renewable. We observed variations in its morphology under different operating conditions in scanning electron microscope images by tuning the operating parameters of ES and using different DMF/CHCl3 solvent ratios. We produced various types of ES nanofibers with uniform fiber diameters ranging from 400 to 2000 nm, which increased filter efficiency and helped overcome existing shortcomings in filter applications. A scanning mobility particle sizer and NaCl aerosol particles of sizes 30–300 nm were used to test the prepared nanofiber filters. Owing to their high specific surface areas/volume ratios and small-fiber diameters, the nanofiber filters with fiber diameters smaller than 500 nm forcefully resisted the majority of suspended particles. The averaged penetration ability of ES fiber was decreased from 30% to 4%, with increasing heating temperature and annealing time. Thicker ES fibers with beaded morphologies exhibited average penetration

Two novel phosphorus-containing copolyesters were synthesized by direct polycondensation reaction of phenyl dichlorophosphate, 1,4-succinic acid and 1,4-butanediol using stannous chloride (SnCl2) and 4-Methylbenzenesulfonic acid as catalyst, and its chemical structures were identified by 1H and 31P nuclear magnetic resonances (1H and 31P NMR). The resulting phosphorus-containing poly(butylene succinate) (PPBS) was characterized by X-ray diffraction (XRD), polarized optical microscope (POM), thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). PPBS can be as a flame retardant for commercial poly(butylene succinate) (PBS). A series of flame retardant composite materials were produced by melt-blending of PBS and PPBS. The comprehensive flame retardant property of composite materials was evaluated by limited oxygen index (LOI). While 20 wt % of PPBS was added into PBS resin, good flame retardant properties could be obtained. Composite materials can have much better flame retardancy (LOI = 30) than neat PBS resin. Thermogravimetric analysis (TGA) showed that the weight loss of PBS was decreased by the introduction of PPBS. In addition, possible flame retardancy mechanism of PPBS in composite materials was analyzed by SEM photos of char residue.

A novel bio-based and biodegradable aliphatic multi-block copolyester, poly(butylene 2-methylsuccinate)-poly(ethylene glycol) (PBMS-PEG), was synthesized from 1,4-butanediol (BDO), 2-methylsuccinate acid (MSA) and poly(ethylene glycol) (PEG) via direct esterification and polycondensation process with tetrabutyl titanate as catalyst. Thermo-sensitive PBMS-PEG micelles were obtained by self-assembly of amphiphilic block copolyesters in aqueous medium by dialysis method. These micelles with different PEG contents have sizes varying from 74.3 nm to 138.3 nm and are stable in water over 200 days without any precipitation. A hydrophobic pesticide, Avermectin, was encapsulated in micelles by the same dialysis method. Such PBMS-PEG micelles can be used as thermo-responsive drug carrier owing to their controlled lower critical solution temperature (LCST) which can be accurately adjusted by varying the PEG proportion. The LCST increases from 27.0 °C to 40.0 °C while increasing the PEG proportion from 30% to 60%. By using the HPLC measurements, the results show when the drug loading is up to 20%, the loading efficiency is still nearly 100%. The properties of these amphiphilic micelles show that the delivery system has a promising potential to be further explored for developing a highly effective and biodegradable hydrophobic-pesticide-release formulation.

A partially bio-based bisphenol containing pendant azido group viz., 4,4′-(5-azidopentane-2,2-diyl) diphenol (AZBPA) was synthesized starting from 4,4′-bis (4-hydroxyphenyl) pentanoic acid. AZBPA was reacted with isophthaloyl chloride (IPC), terephthaloyl chloride (TPC) and a mixture of IPC/TPC (50:50 mol%) by phase transfer-catalyzed interfacial polycondensation route to obtain aromatic polyesters containing pendant azido groups. Copolyesters containing pendant azido groups were also synthesized by polycondensation of different molar proportions of AZBPA and commercially available 4,4′-(1-phenylethane-1,1-diyl) diphenol (BPA-AP) with IPC. Inherent viscosities and number average molecular weights of (co)polyesters were in the range 0.85–1.64 dL/g and 58,900–190,400, respectively, indicating the formation of reasonably high molecular weight polymers. Tough, transparent, and flexible films could be cast from chloroform solutions of these polyesters. X-Ray diffraction analysis showed that (co)polyesters were amorphous in nature. (Co)polyesters were characterized using FT-IR, 1H NMR spectroscopy, XRD, TGA and DSC analysis. The chemical modification of a representative copolyester containing pendant azido groups was carried out quantitatively using copper-catalyzed azide-alkyne cycloaddition (CuAAC) with two alkynes viz., phenyl acetylene (PA) and ethynyl-4-nitrobenzene (ENB). Additionally, (co)polyesters containing pendant azido groups were thermally cross-linked (170 °C/12 h) leading to the formation of network structures based on azide to nitrene decomposition and subsequent reactions on polyester backbone. The selected cross-linked polyesters were characterized by stress-strain measurements. The cross-linked polymers exhibited higher tensile strength and Young’s modulus and lower % elongation at break compared to corresponding pristine polyesters containing pendant azido groups.

In this paper, the synthesis and properties of poly(1,4-cyclohexanedimethylene-co-isosorbide terephthalate) (PCIT) with isosorbide (IS) content ranging from 16 to 61 mol% relative to the total diols amount were investigated. Amorphous polymers were successfully synthesized without isosorbide ring hydration. Glass transition temperature (Tg) linearly increased of 1.1 °C for each molar percent of isosorbide included in the polyester, meanwhile melting temperature (Tm) linearly decreased of 2.1 °C for semi-crystalline samples (up to 25 mol% of isosorbide). Molar masses of semi-crystalline samples were easily increased using high temperature solid-state polymerization (SSP) and reduced viscosity (ηred) higher than 70 mL g−1 were obtained. Semi-crystalline samples exhibit outstanding impact resistance compared with commercial high performance copolyester, whereas amorphous copolyesters exhibit acceptable mechanical properties coupled with high thermal resistance. Results confirmed the promising association between isosorbide and 1,4-cyclohexanedimethanol to reach tunable thermal and mechanical properties, depending on the targeted applications.

Fully biobased copolyesters poly(isosorbide-co-butylene 2,5-furandicarboxylate) (PISBF) were synthesized from 2,5-dimethylfuran dicarboxylate (DMFD), isosorbide (IS) and 1,4-butanediol (BDO) via transesterification and polycondensation reactions. The resulting copolymers were characterized by 1H NMR, 13C NMR, GPC, intrinsic viscosity, DSC, TGA and tensile testing, respectively. The NMR characterizations had confirmed that BDO was successfully introduced into the poly(isosorbide 2,5-furandicarboxylate) (PIF) polyester chains. Over the IS experimental composition range 20–80 % in copolymer chains, PISBF copolymers had TD, 5% values higher than 370 °C and TDM higher than 405 °C, and Tg values within the range of 55 °C and 150 °C. Introduction of BDO units into PIF chains imparted the PISBF copolyester with better mechanical performance than PIF, thus PISBF copolyesters with IS content of 20–50% were strong and toughened copolymers with Young’s modulus about 1400 MPa, tensile strength at break higher than 53 MPa, and elongation at break higher than 46%.

The interaction of (L)-lactic acid with p-tert-butylthiacalix[4]arene containing ethoxycarbonyl fragments in the 1,3-alternate conformation was studied in tetraglyme. For the first time, the lactic acid oligomer was obtained by polycondensation with the macrocycle and characterized by 1H, 13C NMR, IR spectroscopy, MALDI mass spectrometry and gel permeation chromatography. Thermal stability of the obtained copolyester of lactic acid and thiacalix[4]arene was studied by TG/DSC analysis and the effect of the macrocyclic platform on its thermal properties was shown. Copolyester obtained was thermally more stable than oligolactic acid. Self-assembly of synthesized oligomer was studied by dynamic light scattering method. It was shown that monodisperse particles (PDI = 0.13) with the size of 208 ± 4 nm are formed in CH3CN solution at 2.5 × 10−5 M concentration.

Biobased dihydroxy-terminated aliphatic copolyesters were synthesized from melt-polycondensation of 1,6-adipic acid with 1,6-hexanediol and 1,10-decanediol. The isodimorphic behavior of the copolyesters was explored to identify the pseudo-eutectic copolyester, which was selected as macro-initiator for ring opening polymerization of l -lactide to prepare poly( l -lactide)-b-poly(hexamethylene-co-decamethylene adipate)-b-poly( l -lactide) (PLLA-b-PHDA-b-PLLA) triblock copolymers varying PLLA block length. The blocky structure was confirmed by GPC and NMR, and the influence of PLLA block length on physical and mechanical properties was investigated. Impact testing showed that the impressive impact strength was achieved, that is, the values of PLLA10-PHDA-PLLA10 and PLLA20-PHDA-PLLA20 were largely enhanced to 357.2 J/m and 259.6 J/m, respectively, about 9–12 times greater than that of PLLA homopolymer (28.6 J/m). SEM micrographs of impact fractured surface showed that the triblock copolymers underwent a transition from brittle fracture of neat PLLA to ductile fracture, which is attributed to the introduction of flexible aliphatic polyester as middle soft building block of triblcok copolymers. This work demonstrated isodimorphic aliphatic copolyesters as midblock of PLLA-based triblock fully biobased biodegradable copolymers towards highly toughened PLLA material.

Herein, two fully renewable copolyester series, namely poly(pentylene 2,5-furandicarboxylate-co-caprolactone) (PPeCFs) and poly(hexamethylene 2,5-furandicarboxylate-co-caprolactone) (PHeCFs) were successfully synthesized with combining e-caprolactone (CL) with poly(pentylene 2,5-furandicarboxylate) (PPeF) and poly(hexamethylene 2,5-furan dicarboxylate) (PHeF) with different molar ratios. These materials, with a CL content ranging from 10 to 50 mol%, were synthesized for first time using stannous octoate as catalyst via ring opening polymerization (ROP). Their chemical structures and molar composition were evaluated by 1H NMR, 13C NMR and FTIR spectroscopies, while their thermal properties were investigated in detail using Fast Scanning Calorimetry (FSC), Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA). The obtained results, in combination with Wide-Angle-X-ray diffractometry (WAXD), showed that copolymerization of CL with PHeF and PPeF led to semi-crystalline and partially amorphous copolyesters respectively, providing the basis for significant thermal properties enhancement with respect to the polycaprolactone (PCL) homopolymer, and therefore a much wider range of melting points (Tm) and glass transition temperatures (Tg) were obtained. TGA of the new copolymers showed excellent thermal stability, exceeding 310 °C and 360 °C for PHeCFs and PPeCFs respectively, while their decomposition mechanism was evaluated by pyrolysis-gas chromatography/mass spectroscopy (Py-GC/MS). Almost all copolyesters and mainly the ones with 40 and 50 mol% CL content showed accelerated enzymatic hydrolysis rate.

As an essential biodegradable polyester species, poly(butylene succinate) (PBS) is restricted for wider applications due to its low thermal/mechanical properties and unsatisfactory (bio)degradability. Current practice of introducing either stiff or flexible building blocks into PBS main chains remains challenging to achieve a synergistic enhancement of the thermal and (bio)degradability of this material. We herewith report a series of PBS copolyesters based on the carbohydrate-derived isosorbide (1,4:3,6-dianhydro-D-glucidol, IS) (PBIS) by utilizing its unique intrinsic characters of being rigid and hydrophilic. The target copolyesters were constructed with a broad scope of IS content (0–100 mol%) and with random microstructures. The Mn values and the intrinsic viscosities of these polyesters are in the scopes of 7300–38,700 g mol−1 and 0.33–0.82 dL g−1, respectively. The results shown in this work clearly demonstrated that the presence of IS enhances the Tg values almost linearly and simultaneously promotes (neutral, acidic) hydrolytic and enzymatic degradations (with porcine pancreas) of the copolyesters. PBIS copolyester containing 20 mol% IS displays comparable hydrolytic and enzymatic degradation rates with those of PBSA (20 mol% adipic acid), but a substantially 23 °C higher Tg value. Detailed characterization of the molecular structures, micro-sequential structures, molecular weights and polydipersities, thermal properties, hydrophilicities and (bio)degradability are provided. The (bio)degradation and degradation mechanism study of these copolyesters are reported for the first time.

[EN] ZnO compounds exert a catalytic effect on the degradation of polyesters and could affect the biodegradability of such polymers. Herein, composites of 2 wt% of ZnO particles and biodegradable commercial Ecovio polymer, a blend of poly(lactic acid) (PLA) and a copolyester, are prepared by melt extrusion process to further study the effect of the incorporation of ZnO particles on the biodegradability of this polyester under composting conditions. Different nano- and micro-sized ZnO particles are employed to investigate the effect of the size, morphology, and surface charge of ZnO on the physicochemical properties of the polymeric composite and nanocomposite by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). The influence of such compounds on the compost disintegradability is further investigated by different techniques including, gel permeation chromatography (GPC), confocal Raman microscopy and energy dispersive x-ray spectrometer (EDX). The results demonstrate that the ZnO particles significantly accelerate the disintegration process of the Ecovio polymeric blend under a composting environment., This research was funded by the MICINN under the projects PID2019–10460 0RB-I0 0 and MAT2017–86450-C4–1-R , the Spanish National Research Council (CSIC) under the project NANOMIND CSIC 201560E068 , the Agencia Estatal de Investigación (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU). F.R-M is indebted to MINECO for a ‘Ramon y Cajal’ contract (ref: RyC-2015–18626), which is co-financed by the European Social Fund . F.R-M also acknowledges support from a 2018 Leonardo Grant for Re- searchers and Cultural Creators (BBVA Foundation).

Nanocomposites of multiwalled carbon nanotubes (MWCNTs) with poly(butylene adipate-co-terephthalate) (PBAT), a flexible aromatic–aliphatic copolyester, were prepared by melt mixing followed by compression moulding to investigate their spectroscopic, morphological, mechanical and electrical properties. A comparison of the Fourier transform infrared (FTIR) spectra of the neat polymer matrix and the composites showed no difference, implying a physical mixing of the matrix and the filler. A morphological investigation revealed the formation of a continuous and interconnected MWCNT network embedded in the polymer matrix with partial agglomeration. Increasing Martens hardness and indentation modulus and decreasing maximum indentation depth with increasing filler concentration demonstrated the reinforcement of the polymer by the MWCNTs. A volume resistivity of 4.6 × 105 Ω cm of the materials was achieved by the incorporation of only 1 wt.-% of the MWCNTs, which confirmed a quite low percolation threshold (below 1 wt.-%) of the nanocomposites. The electrical volume resistivity of the flexible nanocomposites was achieved up to 1.6 × 102 Ω cm, depending on the filler content. The elongation at the break of the nanocomposites at 374% and the maximum relative resistance changes ( Δ R/ R 0 ) of 20 and 200 at 0.9 and 7.5% strains, respectively, were recorded in the nanocomposites (3 wt.-% MWCNTs) within the estimated volume resistivity range. A cyclic strain experiment shows the most stable and reproducible Δ R/ R 0 values in the 2%–5% strain range. The electrical conductivity and piezoresistivity of the investigated nanocomposites in correlation with the mechanical properties and observed morphology make them applicable for low-strain deformation-sensing.

In this work, biochar was introduced as a filler into the aliphatic-aromatic copolyester and polylactide blend. Properties and the changes during degradation of obtained materials were evaluated. A new application path was also determined by lowering the surface resistivity by increasing the biochar content. Measurements of electrostatic properties showed that surface resistivity of the poly(1,4-butylene adipate-co-1,4-butylene terephthalate)/polylactide/biochar composites is strongly dependent on the biochar content. Six-fold reduction of the surface resistivity after introduction of the 30 wt% of carbon to the reference specimen was observed. Degradation tests were conducted under abiotic and composting conditions. Visual evaluation indicated that the increase of biochar content had caused cracks to increase on the sample surfaces. The values of thermal properties after degradation do not indicated on the biochar influence on polymer matrix degradation mechanism. Nuclear magnetic resonance analysis revealed that after 42 days of hydrolytic degradation amount of polylactide was 0–2%.

Based on the excellent flame retardant performance, environment-friendly and abundant surface functional groups, Carbon Dots (CDs) were adopted as copolymerizable flame retardants for Poly(ethylene terephthalate)(PET) for the first time. The CDs with gelatin as precursor (gCDs) were synthesized by one-step hydrothermal method and copolymerized with pure terephthalic acid (PTA) and ethylene glycol(EG) to prepare flame retardant copolyester (gCDs-PET) based on the hydroxyl and amine groups on the surface of gCDs by in situ polymerization. It is demonstrated that gCDs-PET had showed better smoke suppressant and higher flame retardancy than pristine PET. The limiting oxygen index (LOI) of gCDs-PET composites achieved to 29% with the addition of 2.0 wt% gCDs. What is more, cone calorimeter tests showed that the peak value of heat release rate(pk-HRR) greatly decreased 42.66% and the total smoke production (TSP) reduced 62.64%. Besides, the flame-retardant mechanism disclosed that gCDs catalyzes the thermal decomposition of PET to form a shielding carbon layer, which handicap the release of combustible materials to the outside and expand the as-formed char, so that interrupt the combustion reaction. Furthermore, mechanical properties and spinnability of gCDs-PET was evaluated. It was demonstrated that the addition of gCDs into PET could enhance the mechanical strength and gCDs-PET could be made to fibers with excellent spinnability.

4,4′-biphenyl dicarboxylate modified poly(ethylene terephthalate) (PET) copolyester molecules proximate to glass fiber surfaces in composites are shown to self-order into a liquid crystalline state. Near the glass fiber surfaces, the polymer chains are proposed to align and form more ordered domains increasing translational entropy, which leads to an overall increase in entropy of the system. The frustrated liquid crystalline polymer of this study, when confined near glass fiber surfaces, became more easily ordered, an example of the concept know as “order through entropy”. Solid-phase birefringence, lower molten-phase viscosity and storage modulus were observed and discussed as properties of these new systems. Such glass fiber reinforced PETBB55 composites possess enhanced mechanical and processing properties, a unique combination.

International audience; The aim of this study is to investigate the printability conditions of a copolyester based polymer that has not received yet much attention. This material presents several advantages over PLA and ABS including its food contact compliance and BPA (Bisphenol A) free formulation. The determination of optimal conditions to print copolyester with FDM process was done by quantifying the influence of printing temperature on thermal behavior and tensile properties including Young's modulus, yield stress, tensile strength, ultimate properties, and fracture toughness. Analysis of damage mechanisms through the observation of fracture surfaces of printed copolyester were also performed using SEM. The results indicate a strong relationship between thermal cycling, tensile properties and printing temperature. It is also shownthat the mechanical behavior of printed copolyester is significantly affected by the filament arrangement within the meso-structure. Particular fracture patterns are revealed, which suggest the simultaneous action of three main damage mechanisms triggered by the in homogeneous change in the filament morphology at the rupture point.

To investigate whether dendritic superstructures can be formed from random copolymers, the morphological evolution of a random copolymer, poly(p-dioxanone-co-butylene-co-succinate) (PPBS), is tracked at different crystallization temperatures by optical microscopy. The crystal morphology is regulated by controlling the molecular structure of PPBS as well as the crystallization temperatures, that is, from rounded spherulite for the homopolymer counterpart to dendrites for the copolymer with high p-dioxanone (PDO) content and crystallization temperature. Different from previous works on dendritic crystals, interestingly, film thickness shows no obvious effect on the formation of dendrites. While we find that the crystal growth rate is seriously frustrated by the random structures of PPBS copolyester. Besides, small-angle X-ray scattering (SAXS) analysis indicated that the inter-lamellar region of PPBS copolyester is highly affected by the crystallization temperature. The PDO content, random structure, and high crystallization temperature were believed to be the main factors for the crystals transition from well-rounded spherulite to dendritic crystals.

In terms of risk assessment especially for known and unknown substances migrating from food contact materials, quantification without corresponding reference substances currently poses a challenge. In the present study, the opportunity of a universal response quantification approach was evaluated by using a corona charged aerosol detector (CAD) for liquid chromatography combined with inverse gradient compensation. Characteristics of CAD detection in dependence of substance properties were analyzed with 46 randomly chosen reference substances. An almost equal CAD response (±20%) was achieved for non-volatile substances with a molecular weight of minimum 400 g/mol and a vapor pressure of maximum 10−8 Torr. We empirically defined an analytical parameter, Q50/35, the quotient of CAD peak areas at CAD evaporator temperatures of 50 °C and 35 °C, to predict the adequacy of the CAD universal response approach for quantification of known and unknown analyte substances. Exemplarily, we applied the CAD universal quantification approach for the determination of extractable oligomers below 1000 g/mol from a variety of food contact polycondensate plastic materials (e.g. polyesters like polyethylene terephthalate, polybutylene terephthalate, Tritan copolyester, polyamides 6, 6.6 and 6 T/6I and polyarylsulfones polyphenylsulfone and polyethersulfone). Quantitative results for in total 44 oligomers out of 11 materials were compared with established material-specific quantification methods using extracted oligomer mixtures as well as individual oligomers isolated from the mixtures. CAD-based quantification results were generally in accordance to published quantification approaches for polyamide oligomers and oligomers from polyarylsulfones. For oligomers extracted and isolated from polyester materials a slight underestimation was determined by CAD universal response approach. In terms of detection limits and accuracy, the universal CAD approach exhibits no advantages compared to established UV-methods, to date.

At present, developing a flame-retardant unit to solve the flammability and melt-dripping of poly(ethylene terephthalate) (PET) still is a key issue. To endow PET with good flame retardancy and low smoke releasing, a third monomer, N, N′-bis(2-hydroxyethyl)-biphenyl-3,4,3′,4′-tetracarboxylic diimide (BPDI) containing biphenyl biimide and without any traditional flame-retardant elements, is synthesized and incorporated to the main chain of PET to obtain the P(ET-co-BP)n copolyester via melt polymerization. The thermal stability, combustion and pyrolysis behaviors of the obtained copolyesters have been well investigated. Thermogravimetric analysis (TGA) results demonstrate that introducing BPDI into PET obviously improves its thermal stability and the forming ability of char residue. LOI, vertical UL-94 and cone calorimeter measurements have been applied to investigate the combustion behaviors of P(ET-co-BP)n. The results prove that P(ET-co-BP)n copolyesters containing biphenyl biimide show better fire safety, reflected by lower fire growth rate (FIGRA) and low smoke production. SEM and Raman results suggest that the char layers of P(ET-co-BP)n become denser and mainly consist of polyaromatic species with small and uniform microstructures. The pyrolysis behaviors of the copolyesters are investigated by Py-GC/MS, and the results showed that the biphenyl biimide structure units can lead to rearrangement reactions at high temperature, ultimately forming the phenanthrene ring structures during combustion. Without traditional flame-retardant elements like halogen and phosphorus, this novel PET copolyester is environmentally friendly and more safety.

To improve the flame retardant efficiency of aromatic Schiff base (BA), and adjust the crosslinking temperature of imine groups, a cyano group, an electron-drawing group has been introduced into the chemical structure of aromatic Schiff base to obtain a third monomer for poly(ethylene terephthalate) (PET), named as dimethyl-5-[(2-cyanobenzylidene)amino]-isophthalate (CBAA). Thermogravimetry-differential scanning calorimetry (TG-DSC) and dynamic rheological results prove that the PET-based copolyester containing CBAA (CBAAnPETs) can cross-link at higher temperature than that containing BA, which will not affect the preparing and processing of PET. DSC and wide angle x-ray diffraction (WAXD) results demonstrate CBAAnPETs remain good crystallization ability. Owing to the two types of cross-linking reactions, i. e. the reactions between Schiff base ( CH N-) and cyano group (-C≡N), and among -CH N- units, CBAA plays an important role in solid phase as well as gaseous phase endowing CBAAnPETs with excellent flame retardancy. With a low CBAA content (only 6.7 mol%), the copolyesters self-extinguish in 5 s with no melt drips in UL-94 vertical test, and its LOI value also increases to 31.0%. The peak heat release rate and total smoke release of the copolyesters obtained from cone calorimetry also observably decrease.

Two series of biobased even-odd aliphatic copolyesters, poly(butylene glutarate-co-butylene azelate) (PBGA) and poly(octylene glutarate-co-octylene azelate) (POGA), were prepared from even diol of 1,4-butanediol or 1,8-octanediol with odd diacids of glutaric acid and azelaic acid, respectively. These even-odd copolyesters can cocrystallize within the entire composition range despite being random, displaying a pseudo-eutectic point when their melting points are plotted as a function of composition. DSC and WAXD studies confirmed the isodimorphic behavior for PBGA and POGA. Then, the competition and miscibility in isodimorphism between PBGA and POGA were comparatively investigated. It demonstrated that the chain length of comonomeric diols can exert a considerable influence on the isodimorphic behavior of copolyesters. The comonomeric diol with longer chain shows greater ability in bridging the gap of competition between comonomer units. This insight contributes to predicting the composition of crystal transition point for isodimorphic copolyesters based on the molecular structure. For miscibility, the mutual insertion of comonomer units in the copolyester containing longer comonomeric diol is easier than in the copolyester with shorter comonomeric diol. Furthermore, a close dependence between the mechanical properties with competition and miscibility in such even-odd copolyesters was observed and discussed. The composition dependence of yield stress presents a similar pseudo-eutectic behavior that matches those exhibited by Tm versus composition, and that of the elongation at break shows an opposite tendency. In conclusion, our work here not only clarifies the effect of chain length of comonomeric diols on competition and miscibility of isodimorphism in the even-odd copolyesters, but also provides guidance in the selection of comonomeric diol for preparation of aliphatic copolyesters with desirable performances.

Extruded 70/30 poly (butylene adipate-co-terephthalate) (PBAT)/polylactic acid (PLA) blends incorporated with 0.5, 1.0, 1.5 and 2 wt.% of egg white [albumen (ABM)] were investigated to determine the effect of ABM on the microstructure and antimicrobial properties of PBAT/PLA blend. Microstructural analysis revealed immiscibility in the two polymers, due to the presence of distinct melting points, heterogeneous phase and vibrational frequencies unique to each polymer. Thermal and tensile testing also suggests that the inclusion of ABM tailored the blend and significantly improved its thermal stability and flexibility, since 0.5 and 1.0% (wt./wt.) ABM led to 490 and 432% improvement in elongation, respectively. Furthermore, the ternary blend films in contact with Salmonella enteritidis (S. enteritidis) showed significant inhibition to growth for 24 h, but some bacterial cells grew when the film were removed. This study demonstrates the fabrication of ABM tuned potential biopolymer packaging flexible blend with bacteriostatic properties.

Bonding aryl groups with carbon-nitrogen double bond is a critical structural factor for the self-crosslinking of Schiff bases at high temperature. In this study, a novel aromatic Schiff base “5-(benzylidene-amino)-isophthalic acid dimethyl ester (BA)” has been designed as a self-crosslinking monomer for poly(ethylene terephthalate) (PET) based copolyesters (BAnPETs). The cross-linking behaviors, flame retardancy and non-dripping performance of BAnPETs have been investigated by simultaneous thermal analysis (TG-DSC), dynamic rheology, limiting oxygen index (LOI), UL-94 vertical burning and cone calorimetry tests. It is found that BA units can cross-link during combustion resulting in high melting viscosity and enhance char forming for BAnPETs, which endows the copolyesters with excellent flame retardancy and non-dripping behavior. Incorporating of BA with a low content (only 7.7 mol%), the LOI value of copolyester increases from 22.0% to 31.0%, and at the same time it achieves V-0 rating in the UL-94 vertical burning test. The mode action of Schiff bases on flame retardation and anti-dripping of copolyesters also has been investigated, and the results show that the aromatic Schiff base groups can lead copolyesters to form nitrogen-containing cross-linkable networks and further transform into compact char layer during combustion. The char layer which acts as an effective barrier, cuts off oxygen, hinders the volatilization of combustible gas and isolates unburned polymer from fire resource. This work suggests that using Schiff base as a self-crosslinkable monomer is a new and effective way for fire-safe polymeric materials.

The flexible strain sensors that integrate optical and electric signals are rather limited, although the flexible sensor community has witnessed increased progresses. Herein, we have fabricated stretchable polymer composites showing both mechanically modulated fluorescence and electric resistance by using polyester elastomer, zinc phthalocyanine (ZnPc) and silver nanowires (Ag NW) as basic components. Specifically, the strain variation in the range of 0–30% and 50–400% can be well correlated with the alternation of electric resistance and red fluorescence of flexible composites, respectively. The present work will open the way for the large-scale fabrication of multi-functional flexible strain sensors.

This paper focuses on the effects of cyclic water immersion and salt spray aging tests on the physical properties of aromatic thermosetting copolyester (ATSP) matrix. Neat and graphene nanoplatelet (GNP) incorporated nanocomposite ATSP foam morphologies are employed to have enhanced surface areas exposed to the surrounding aqueous media, via porous configurations, which deliberately aggravate the extent of the aging on the matrix. The ATSP foams are fabricated through a thermal condensation polymerization process. Upon exposures to the periodic aging conditions, ATSP demonstrates an adsorption-regulated mass uptake mechanism. Contact angle measurements reveal GNP-neutral and hydrophobic characteristics for the ATSP matrix. Microstructural imaging exhibits no substantial physical degeneration in the matrix caused by the accelerated aging conditions. Glass transition temperatures of both neat and nanofiller incorporated ATSP forms display only marginal decreases stemmed from small volumes in the matrix occupied through the hygroscopic swelling. Thermal degradation stability of the ATSP morphology is effectively preserved following the aging processes. Compressive mechanical strengths of the foams lie within the regime of their virgin (not exposed to the aging conditions) counterparts yet show slight reductions. The ATSP matrix demonstrates an outstanding aging resistance to the subjected environments which can potentially address high-performance requirements in cutting-edge industrial applications.

New potentially biobased copolyesters having the same ethylene skeletal structure as poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) were synthesized based on 1,2-propanediol (1,2-PD) or 2,3-butanediol (2,3-BD) with 1,4-cyclohexane dimethanol (CHDM). The compositions of each copolyester were confirmed using 1H-NMR spectroscopy, and the detailed structure was analyzed using 2D NMR spectroscopy. In order to observe the effect of the lateral methyl groups on the microstructure and randomness in the sequences of the copolymers, 13C-NMR spectroscopy analysis was performed. The thermal properties, mechanical properties, and crystallinity of the copolyesters were analyzed using differential scanning calorimetry, thermogravimetric analysis, universal testing machine, and wide-angle X-ray diffraction. Depending on the number of the lateral methyl groups and the contents of the ethylene diol units, the copolyesters displayed different densities, glass transition temperatures (Tg), degrees of randomness and mechanical properties; however, a notable difference was not observed in thermal stability or crystallinity.

Novel copolyester thermoplastics based on 4,4′-bibenzoate and 3,4′-bibenzoate moieties with ethylene glycol were synthesized via melt polycondensations. Crystallization behavior was modified by the additional incorporation of terephthalate or isophthalate units into the backbones. Copolyester compositions were verified by 1H NMR spectroscopy and molecular weights were assessed using inherent viscosity (ηinh). Thermogravimetric analysis (TGA) showed single-step weight losses in the range of 360–400 °C. Differential scanning calorimetry (DSC) was used to determine melting points and glass transition temperatures over a wide range of copolyester compositions. Observation of thermal data was used to identify amorphous windows in composition ranges containing 3,4′BB and 4,4′BB moieties. Dynamic mechanical analysis (DMA) provided information about thermal transitions and sub-T g relaxations. Mechanical data were obtained using tensile testing to expand structure-property- morphology relationships. Permeability analysis helped to understand how monomer symmetry affects oxygen diffusivity and solubility in selected amorphous film and biaxially oriented copolyester samples.

A long-chain branched copolyester (i.e. p-hydroxybenzoic acid (HBA)/2-hydroxy-6-naphthoic acid (HNA)/1,1,1-tris(4-hydroxyphenyl)ethane (THPE) copolyester) and its extrusion film with superior physical properties to commercial Ticona A950 and Vecstar CTZ have been manufactured by the design of appropriate prescriptions, T-Die extrusion, and thermal treatment of crystal transformation. In order to investigate the fabricating feasibility for flexible copper clad laminate (FCCL) of fourth/fifth generation long-term evolution (4G/5G LTE), we have also agglutinated lab-made copolyester extrusion film with the copper foil by hot compression. Experimental results manifest that lab-made copolyester extrusion film is a highly potential FCCL substrate of 4G/5G LTE because its thickness, dielectric constant (Dk), dielectric loss (Df), hygroscopicity, yellowness index (YI), antistatic capability, flammability, melting temperature (Tm), coefficient of thermal expansion (CTE), and peel strength to copper foil are 50 μm, 2.90, 0.00140, 0.04%, 2.7, 6.5 × 109 Ω/□, UL-94 V0, 305 °C, 24.8 ppm/°C, and 29.9 lb/in, respectively.

Through a two-stage transesterification/esterification and polycondensation method, three biobased poly(hexamethylene 2,5-furandicarboxylate-co-adipate) (PHFA) copolyesters with low contents of hexamethylene adipate (HA) units were synthesized in this research. The thermal properties, crystal structure, and tensile properties of PHFA copolyesters and poly(hexamethylene 2,5-furandicarboxylate) (PHF) homopolymer were extensively studied and compared with each other. All PHFA copolyesters still maintained good thermal stability. The glass transition temperatures, melting point temperatures, and equilibrium melting point temperatures of PHFA copolyesters gradually decreased with the increase of HA units. PHFA copolyesters displayed the same crystal structures as PHF. The elongation at break remarkably increased to 498.3 ± 12.0% for the PHFA copolyester containing 30 mol% of HA units (PHFA30) from 197.3 ± 12.2% for PHF; moreover, PHFA30 still showed a relatively high melting point temperature of 116.4 °C, similar to that of biodegradable poly(butylene succinate) (about 114 °C).

Divanillic acid, the dimer of vanillic acid, has been widely used as an aromatic building block of bio-based polymers. In this study, a series of homo- and copolyesters composed of a methylated dialkoxydivanillic acid monomer with an alkoxy side-chain length of 1 or 4 carbon units, cyclohexanedimethanol, and an alkanediol with a chain length of 6, 8, or 12 carbon units was synthesized. The polyesters obtained exhibited high weight-average molecular weights in the range of 4.4 × 104 to 20 × 104 g/mol and degradation temperatures higher than 380 °C. Thermo-pressed films were prepared from all the polyesters. Their glass transition temperature and elongation-at-break values could be tuned from −1 to 120 °C and 3% to 1500%, respectively, by changing the lengths of the alkoxy side chain and the alkanediol as well as the composition of the copolyester.

High molecular weight aliphatic-aromatic copolyesters were synthesized from Sebacic acid, terephthalic acid, 1, 4-butanediol and glycerol via two-step esterification and polycondensation. Copolyesters were characterized with intrinsic viscosity, gel permeation chromatography, X-ray diffraction, Fourier infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, rheological analysis, tensile and puncture testing. All the copolyesters had a weight-average molecular weight over 20,000 g/mol or intrinsic viscosity over 1.1 dL/g when the glycerol content was in the range from 0.04 to 0.1 mol. Particularly, in addition to a small reduction in the tensile strength and elongation at break, the molecular weight, crystallinity, and intrinsic viscosity of the polyester were increased when the glycerol content was 0.04 mol, and the puncture resistance reached its maximum, which would improve the performance of the copolyester film. Obviously, the addition of glycerol did not significantly affect the melting temperature, glass transition temperature and thermal stability of polyesters, which would make it possible to use copolyester as a base material for cold-resistant hydrogels. As a whole, the level of glycerol within 0.1 mol is sufficient to improve the properties of copolyesters, which is beneficial to promote the generalization of them for films and hydrogels.

Sustainable biobased terpolyester based on heterocyclic dimethyl furan-2,5-dicarboxylate and isosorbide in combination with ethylene glycol and 1,4-cyclohexanedimethylene (PEICF) were successfully synthesized by two-step melt polymerization method and characterized. A series of PEICF terpolyester exhibited excellent heat resistive properties, with glass transition temperatures of 81–119 °C, and high molecular weights (Mw = 50,800 g mol−1). When esterification was carried out at fixed a COOH:OH molar ratio of 1:2, 1,4-cyclohexanedimethanol (CHDM) showed increased reactivity compared to isosorbide (ISB) and ethylene glycol (EG) monomers. As a result, EG was most likely to be placed at the end of the oligomer chains, which accelerated the transesterification process and drastically increased chain growth via chain scission at the carbonyl carbon adjacent to the ethylene unit due to steric hindrance. The zero shear viscosities of the PEICF terpolyester were much higher than that of the copolyester and increased with increasing ISB content. This study proposed a method for improving the low reactivity of dimethyl furan-2,5-dicarboxylate, which shows suppressed furan ring flipping, with sterically hindered ISB by using highly reactive CHDM at atmospheric pressure. These results signify the importance of controlling the synthetic conditions, as they affect the composition of the polymer backbone due to the different reactivities, volatilities, and steric hindrances of the monomers.

Retro-Diels-Alder reaction (rDA) has been widely used as a common modification approach for expanding functional applications of polymers. Especially, it has become an effective method of current cross-linking chemistry. With the goal of designing a cross-linkable PET-based copolyester toward flame retardancy and anti-dripping during combustion, dimethyl 5-(1,3-dioxo-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindol-2(3H)-yl) isophthalate (DMTMI) was incorporated as the functional co-monomer into PET chains via random transesterification polycondensation. Thermogravimetry-differential scanning calorimetry (TG-DSC) and rheological studies demonstrated the existence of cross-linking behavior at high temperature. By controlling the co-monomer content, expected flame retardancy was obtained, as illustrated by the results from the limiting oxygen index (LOI) and cone calorimetry. Furthermore, LOI values increased firstly and then decreased with the content of DMTMI increased, which was related to the existence of rDA reaction, and further proposed that a competitive relationship between the release of inflammable cyclopentadiene during rDA reaction and cross-linking behavior occurred in combustion. The hypothesis was verified through pyrolysis-gas chromatograph-mass spectrometry (Py-GC-MS).

Novel poly(lactic acid)-based chain extended triblock copolymers have been successfully synthesized in melt. The new polymers are characterized by a triblock ABA architecture, where A, is poly(lactic acid) and B is an ad hoc synthesized random biobased aliphatic copolyester poly(propylene/neopentyl glycol succinate). PLLA homopolymer has been also prepared for the sake of comparison. The samples under study were deeply characterized from the molecular, thermal and structural point of view. Mechanical and barrier properties and compostability were also investigated, in order to assess the potentiality of these materials in food packaging applications. The results obtained show that copolymerization leads to better mechanical response and barrier properties with respect to poly(lactic) acid homopolymer. Moreover, the presence of the central B block in the main polymer chain facilitates the process of compostability.

High glass transition temperature (Tg) polyesters based on cycloaliphatic diols such as 1,4-cyclohexanedimethanol (CHDM) and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) have attracted significant interest as bisphenol-A replacement. Whereas most literature reports focus on synthetic approaches, the present study investigates in depth various structure-property relationships in CHDM- and TMCD-containing novel copolyesters. Significant enhancements in Tg and increases in fragility are observed with the incorporation of bulky CHDM and rigid TMCD as comonomers. Substantial increase in oxygen permeability is measured with the incorporation of CHDM from 14.3 for poly(ethylene terephthalate) to 52.6 cc-mil/100in2.day.atm (SPU) for poly(1,4-cyclohexyldimethylene terephthalate). When 35 mol% CHDM is replaced by TMCD as comonomer, the value further increases to 137.0 SPU. In the case of CHDM-containing polyesters, improvements in both sub-Tg molecular mobility (due to additional chair-to-boat transformations) and fractional free volume (FFV) result in an increase in oxygen diffusion. On the other hand, substituting 35 mol% CHDM with more rigid TMCD yields a suppressed β-relaxation. In particular, CHDM-based copolyesters follow a linear correlation between the strength of β-relaxation and diffusivity whereas the TMCD-based copolyester exhibits a significantly positive deviation from the correlation. Therefore, the much higher FFV in TMCD-containing polyester plays a more important role in determining oxygen transport through such polymer. Finally, we demonstrate that copolyesters based on CHDM and TMCD display significantly enhanced resistance to moisture-induced plasticization and the competing penetrant effect.

In this study, we present carbon nanoparticle incorporated high-performance aromatic thermosetting copolyester (ATSP) nanocomposite foams. The ATSP nanocomposite foams were fabricated through a facile solid-state mixing method wherein carboxylic acid and acetoxy-functional group oligomers were initially combined with chemically pristine carbon nanofillers separately, while in powder form. The mixtures were then subjected to a thermal condensation polymerization reaction in which the constituent oligomers formed the ester backbone of the ATSP matrix and advanced the molecular weight while acetic acid was emitted as the by-product, and generated a porous nanocomposite morphology. As compared to a neat ATSP foam, the nanocomposite foams exhibited a reduced coefficient of thermal expansion by 25% to 75 × 10 −6 °C −1 . Thermal stability temperature at 5% mass loss was increased by 30 °C exceeding 500 °C. Compressive mechanical strength was enhanced two-fold, reaching 16 MPa along with a nearly doubled fracture strain, which ultimately yielded improved material toughness.

ABA triblock copolyesters were synthesized by ring-opening polymerization (ROP) of l -lactide in solution initiated by a telechelic d -glucose-based polyester macroinitiator. The macroinitiator with a number-average molecular weight about 2500 g mol−1 was synthesized by non-stoichiometric polycondensation in the melt of 2,4:3,5-di-O-methylene- d -glucitol and dimethyl succinate. Two triblock copolyesters of Mn ranging between ∼6000 and ∼9000 g mol−1, and differing in the length of the polylactide blocks were prepared. These copolyesters started to decompose when heated at ∼220 °C and degraded slowly upon aqueous incubation under physiological conditions. They did not display any perceivable crystallinity and showed a single glass transition temperature (Tg) around 60 °C with the higher value corresponding to the larger content in glucitol units. The copolyesters were able to form nanoparticles with average diameters of ∼100–130 nm and satisfactory dispersity. The effect of the block lengths on size, ζ-potential values and physical stability of the nanoparticles was evaluated. A molecular dynamics simulation study allowed modelling the two-phase structure of the nanoparticles and evidenced the preference of the glucose-based block to be peripherally located.

WOS: 000399499000074, In this work, we introduce a three-layer sandwich composite structure having an aromatic thermosetting copolyester (ATSP) foam core with two aluminum foam face layers joined together by an in situ generated foaming mechanism. The ATSP foam core was synthesized on-site between the aluminum foam layers via a heat-induced polycondensation reaction. Upon curing, the ATSP foam core adhered to the aluminum foam layers through an interfacial compatibility-enabled chemical bonding. Lap shear experiments demonstrated that the bond strength clearly surpassed the tensile performance of the bare aluminum foam parts. Drop-weight impact tests showed that the three-layer sandwich structure could absorb four times the impact energy as compared to the bare aluminum foam of the same overall thickness. (C) 2017 Elsevier B. V. All rights reserved., National Science Foundation (NSF) I/UCRC [IIP-1362146], We sincerely thank Dr. David Farrow for helping with the experiments. We gratefully acknowledge funding from the National Science Foundation (NSF) I/UCRC grant (IIP-1362146). The findings, conclusions, and recommendations expressed in this manuscript are those of the authors and do not necessarily reflect the views of the NSF.

Copolymers based on d , l -lactide (D,L-LA) and ethylene brassylate, with EB molar contents ranging from 3 to 39%, were synthesized by ring-opening polymerization at 130 °C using triphenyl bismuth. The poly (D,L-LA-co-EB) presented a random distribution of sequences ( R →1), resulting in a fully amorphous structure with T gS between −17 and 43 °C that exhibited upgraded thermal stability and a final degradation temperature of ∼450°, which was approximately 100 °C higher than that observed for PDLLA. The incorporation of EB led to mechanical behaviour with improved flexibility and ductility, compared to polylactides. Moreover, the impact was greater than that provided by other monomers such as e-caprolactone or δ-valerolactone. A macrolactone molar content of only 5% was enough to increase the elongation at break from 2 to 87% but its elastic modulus remained around 1 GPa, whereas the copolymer with 16% EB (T g at 17 °C) displayed a clear elastomeric curve with secant modulus of 2.0 MPa and a tensile strength of 0.3 MPa at 1400% of strain (when the specimens did not break). Likewise, the disordered chain microstructure distribution of these copolymers with short sequence lengths of L-LA, D-LA and EB allowed high degradation rates (K Mw ) in the range of 0.055–0.062 per day, with a maximum K Mw for the copolyester containing 9% of EB. In contrast, PDLLA and the 97:3 D,L-LA-co-EB copolymer, owing to their high resistance to water uptake and their packed and rigid amorphous phase, showed degradation velocities of only 0.012 and 0.021 per day, values that are slightly higher than that of poly ( l -lactide) whose rate is 0.011 per day.

In order to prepare white fluorescent polymer materials, poly(ethylene succinate-co-cyclohexane dimethanol) (PESC) emitting blue fluorescence and poly (butylene terephthalate-co-propylene terephthalate) (PBTT) modified with 1,6,7,12-tetrachloroperylene tetracarboxylic acid dianhydride (TTAD) are prepared individually by melt polycondensation. Then the two polymers were linked to form a block polymer PESC-b-PBTT by chain extension reaction. The chemical structure, fluorescence emission and crystallization melting behavior of copolyesters are characterized by nuclear magnetic resonance (1H NMR), fluorescence spectrophotometer and differential scanning calorimetry (DSC). The effect of the ratio of PESC and PBTT in PESC-b-PBTT on the fluorescence properties of the products is discussed. The results shows that the fluorescence color of the material can be controlled by adjusting the proportion of each block in the PESC-b-PBTT copolymer. When the PESC’s content reaches 85wt%, the product emits white fluorescence which can be controlled by isothermal crystallization. Attributed to the increase of crystallinity and crystal size caused by the rise of isothermal crystallization temperature, blocking the energy transfer of blue light unit to orange light unit, the fluorescence of the sample turns to cool white gradually.

Adhesives with reversible bonding characteristics are useful in different applications which demand assembly and disassembly of components, over repeated times. To achieve reversible bonding, the bonding strength of the adhesives on the substrate should be sufficiently high to ensure cohesive failure and with minimized adhesive failure after each bond/debond cycle. This study aims at investigating the bonding strength of an aromatic thermosetting copolyester (ATSP) adhesive deposited on aluminum substrates prepared with conventional sandblasting technique, and laser surface texturing. The deposited ATSP coating was bonded at a temperature of 340 °C and debonded at various temperatures from 25 to 200 °C using a bond strength tester. The reversibility of the coating was shown through multiple bond/debond cycles. The experimental findings revealed significant improvement of bond strength through laser surface texturing, compared to sandblasting by more than 27–63% for debonding at temperatures from 25 to 200 °C. Failure analysis of the coatings showed the predominance of adhesive and cohesive failure for sandblasted and laser textured substrates, respectively. The role of surface topography parameters was investigated for each substrate preparation method, and correlated to the bond/debond experiments.

A series of biodegradable copolyester of poly (butylene succinate-co-butylene malate) (P (BS-co-BM)) bearing hydroxyl groups were prepared by one-pot synthetic strategy without hydroxy-protection. The structure and properties of the P (BS-co-BM) were characterized by nuclear magnetic resonance (1H NMR), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), polarized optical microscope (POM), contact angle tester and enzymatic degradation. The results showed that the P (BS-co-BM) manifested excellent thermal properties. The glass transition temperature (Tg) of the P (BS-co-BM) increased with malic acid units added, the crystallizability temperature (Tc) decreased from 72.6 °C to 21.7 °C, and the melting point temperature (Tm) decreased from 117.9 °C to 82.4 °C. The crystallization rate of poly(butylene succinate) (PBS) segment within P (BS-co-BM) was improved by the introduction of malic acid. The enzymatic degradation rate increased with hydrophilicity of the copolyester improving.

Several aliphatic long chain polyesters with intrinsic viscosity of 0.80-1.47 dL/g were synthesized from biobased 1,5-pentanediol and long chain α,ω-diacids with 10-16 carbon atoms. Their chemical structure was characterized, and thermal, mechanical and gas barrier properties were assessed. These long chain polyesters have a melting temperature higher than poly(e-caprolactone) and manifest polyethylene-like rapid crystallization, good thermal stability and ductile tensile behavior. Their melting temperature, crystallizablity, tensile modulus and oxygen and water vapor barrier performance all increase with increasing the chain length of diacid. In comparison with the widely used biodegradable poly(butylene adipate-co-terephthalate) copolyester, these potentially biodegradable polyesters show comparable tensile strength, ductility and oxygen barrier performance, but obviously superior crystallizability, tensile modulus and water vapor barrier performance.

Slow-release fertilizers have been widely used to promote agricultural production with less losses to the environment. However, further achievement of fertilizer with precisely regulable release performance is still full of challenges, especially for the most used nitrogen fertilizer – urea. In this study, we provide a strategy for regulating performance of slow-release urea fertilizer (SRUF) based on inclusion complexation between biodegradable copolyester and urea via simply changing chain composition. The units of butylene adipate (BA) are copolymerized into the main chains of poly(butylene succinate) (PBS) to obtain a series of random copolyesters of poly(butylene succinate-co-butylene adipate) (PBSA). The crystallizability of PBSA declines with increasing BA content, leading to the longer slow-release time for corresponding PBSA/urea inclusion complex fertilizer. The monotonous, nearly linear relationship between chain composition and the slow-release performance of SRUF has been demonstrated, revealing the great potential to design SRUF with precise slow-release time. Consequently, pot trails in the lab are employed to evaluate the promotion effect of SRUF on Brassica chinensis L.. The growth indexes of plants significantly increase with increasing BA content in PBSA chains used in SRUF of inclusion complex. The plants reach about twice of dry weight in optimized group by referring to neat urea group when the SRUF shows a release duration closely matching to the growth cycle of Brassica chinensis L.

Poly(1,4-butylene-co-1,4-cyclohexanedimethylene 2,5-furandicarboxylate) (PBCFs) was synthesized from bio-based 2,5-furandicarboxylic acid (FDCA), 1,4-butanediol (BDO) and 1,4-cyclohexanedimethanol (CHDM). The GPC showed that the number average molecular weight (Mn) of PBCFs were in the range of 38400–44200 g/mol and the average molecular weight (Mw) varied from 83,000 to 94,800 g/mol with the polydispersity index of 2.22–2.33. The chemical structures, compositions and sequence distributions of PBCFs were confirmed by 1H NMR and 13C NMR. Their thermal properties and crystallization behavior were investigated by Differential Scanning Calorimeter (DSC). Results showed that the glass transition temperature (Tg) and melting temperature (Tm) of poly(butylene 2,5-furandicarboxylate) (PBF) were increased from 38 and 171.8 °C to 65.8 and 211.7 °C for PBCF-68, respectively. Furthermore, the strength and modulus were increased from 44 and 950 MPa for PBF to 69 and 1360 MPa for PBCF-68 with the mole percentage of CHDM units of 68% in diol units. PBCFs demonstrated much better thermo-mechanical properties when compared with those of PBF, which might be used as the bio-based engineering plastic or excellent packaging materials with high transparency and good gas barrier properties.

Polylactide (PLA)/poly(1,4-cyclohexanedimethylene isosorbide terephthalate) (PEICT) blends were prepared by melt processing. Oligomer, with multiple epoxy functional groups, were introduced as a reactive compatibilizer to enhance interfacial adhesion of the two blend components. The reaction between the reactive compatibilizer and blend components was confirmed by infrared spectroscopy and rheological analysis. The improved compatibility of the blends reduced interfacial tension between polymer components, yielding a co-continuous phase morphology from a sea–island morphology. The added PEICT improved the impact strength of PLA to 22.5 kJ/m2 at 40% loading. After compatibilization and the impact strength of PLA/PEICT blends increased to 44.1 kJ/m2, showing that increased interfacial adhesion improved energy transfer between the polymers.

Poly(butylene adipate-co-terephthalate) (PBAT) possesses excellent film-forming ability and biodegradability. Therefore, it is considered to be a promising mulching film material that eliminates the need for recovery. In the applications that require PBAT degradation in the field after use, it is important to understand the biodegradation mechanism at moderate temperatures. We have previously isolated from the soil the mesophilic actinobacterium Rhodococcus fascians NKCM2511 that biodegraded PBAT under moderate temperature conditions (20–30°C). In this study, to clarify the mechanism of PBAT degradation by the strain NKCM2511, a DNA fragment carrying the gene pbathRf responsible for the PBAT degradation activity was cloned. The gene encoded a 216-amino-acid-long protein designated as PBATHRf. Homology modeling revealed that PBATHRf belongs to the α/β hydrolase fold family, lacking the lid domain covering the active site. PBATHRf degraded PBAT film at 30°C at the rate of 0.10 ± 0.03 mg/cm2/d and was capable of degrading several other aliphatic polyester films. Liquid chromatography-mass spectrometry revealed that PBATHRf preferentially cleaved the ester bond between 1,4-butanediol and adipic acid rather than that between 1,4-butanediol and terephthalic acid (T). This characteristic of PBATHRf may explain the low degradation rate of the aliphatic-aromatic copolyester PBAT, compared to the rate of degradation of aliphatic polyesters without T. In addition, liquid chromatography showed that PBATHRf released T, mono(2-hydroxyethyl) terephthalic acid, and bis(2-hydroxybutyl) terephthalate from an amorphous poly(ethylene terephthalate) (PET) film. However, no significant change in the PET film surface after the treatment with PBATHRf was found by scanning electron microscopy. This is the first report of an enzyme from the mesophilic actinobacteria Rhodococcus fascians that can hydrolyze various polyesters, including PBAT, and catalyze hydrolysis on the surface of an amorphous PET film. This study also provides insight into the biodegradation mechanism of PBAT in the actual field as it describes an enzyme from a naturally occurring organism that acts in the medium temperature range.

Blending polylactide (PLA) with flexible polymers is usually capable of reducing its inherent brittleness, which, however, is accompanied with a substantial decrease in tensile strength. Here, considering the integration of flexibility and rigidity, 1,4-butanediol and dodecanedioic acid with flexible alkyl chains as well as isosorbide with a rigid cyclic sugar structure is used to synthesize a new bio-based copolyester. By virtue of interfacial compatibilization between PLA and the copolyester via dicumyl peroxide-induced dynamic vulcanization, well balanced mechanical properties are achieved for resulting blends, that is, elongation at break and notched impact strength are increased to 298.4% and 578.0 J/m that represent 37- and 24-fold increases, while tensile strength maintains at 59.5 MPa that decreases by only ~15% compared with that of neat PLA. Massive shear yielding of PLA matrix triggered by internal micro-voids accounts for the toughening mechanism. Given the high mechanical strength and supertoughness, the PLA-based materials have potential applications in different areas.

A new Schiff base flame retardant monomer with nitro group ( NO2), 5-((4-nitrobenzylidene) amino) isophthalic acid (NBA) was firstly synthesized to prepare fire-safety PET copolyester (NBAnPET). The group of NO2 passivated the cross-linking reactivity of Schiff Base by affecting the formation of the intermediate states of the cross-linking reaction and further to improve the cross-linking temperature of NBAnPET to the temperature range (347–372 °C) from that of (250–348 °C), which showed better machinability in a broad processing temperature zone. In additional findings, the new synthesized NBA Schiff Base helped to shorten the time of polycondensation of PET with the advantage to save 58% of the reaction time by its acid structure. And the group of NO2 enhanced the thermal stability of NBAnPETs, which improved its residue char in high temperature to enhance its flame retardancy. NBA10PET with NBA (7.9 mol%) processed LOI of 32% and V-0 of UL-94 without drip. The analysis of mechanism showed that the group of NO2 in NBA did not decompose into the gas phase and NBA performed the mechanism of condensed phase during combustion of Schiff Base modified PET. The newly prepared NBAnPET with these better properties could possess wider application prospects.