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Poly(1,4-butylene succinate) (PBS) is a promising sustainable and biodegradable synthetic polyester. In this study, we synthesized PBS-based copolyesters by incorporating 5–20 mol% of –O2CC6H4CO2– and –OCH2CH2O– units through the polycondensation of succinic acid (SA) with 1,4-butanediol (BD) and bis(2-hydroxyethyl) terephthalate (BHET). Two different catalysts, H3PO4 and the conventional catalyst (nBuO)4Ti, were used comparatively in the synthesis process. The copolyesters produced using the former were treated with M(2-ethylhexanoate)2 (M = Mg, Zn, Mn) to connect the chains through ionic interactions between M2+ ions and either –CH2OP(O)(OH)O− or (–CH2O)2P(O)O− groups. By incorporating BHET units (i.e., –O2CC6H4CO2– and –OCH2CH2O–), the resulting copolyesters exhibited improved ductile properties with enhanced elongation at break, albeit with reduced tensile strength. The copolyesters prepared with H3PO4/M(2-ethylhexanoate)2 displayed a less random distribution of –O2CC6H4CO2– and –OCH2CH2O– units, leading to a faster crystallization rate, higher Tm value, and higher yield strength compared to those prepared with (nBuO)4Ti using the same amount of BHET. Furthermore, they displayed substantial shear-thinning behavior in their rheological properties due to the presence of long-chain branches of (–CH2O)3P=O units. Unfortunately, the copolyesters prepared with H3PO4/M(2-ethylhexanoate)2, and hence containing M2+, –CH2OP(O)(OH)O−, (–CH2O)2P(O)O− groups, did not exhibit enhanced biodegradability under ambient soil conditions. [ABSTRACT FROM AUTHOR]

Objects. Due to the polymer waste accumulation, the search for new directions for their utilization is urgent. Chemical recycling methods are of considerable interest, which allow one to obtain the original monomers or change the compositions of the copolymers. From the point of view of building a circular economy, a promising material is polyethylene terephthalate (PET), on the basis of which amorphous copolyesters can be obtained. The study aimed to analyze the simultaneous glycolysis and interchain exchange reactions of PET in the presence of the oligoethylene phthalate modifier with hydroxyl end groups and the study of isothermal crystallization of poly(ethylene phthalate-co-terephthalates) with different phthalate contents obtained in this way.Methods. Oligoethylene phthalate is synthesized by polycondensation. Poly(ethylene phthalateco-terephthalates) were obtained by the interaction of post-consumer PET with oligoethylene phthalate. The composition of the oligomer and copolymers was confirmed using Fourier-transform infrared spectroscopy, thermal characteristics and crystallization half-times were determined by differential scanning calorimetry.Results. In this work, the use of the post-consumer PET chemical recycling process, aimed at obtaining copolyesters under the influence of small modifier amounts was proposed. The process consisted in carrying out the combined interchain exchange and degradation with a complex oligoester different from PET. Poly(ethylene phthalate-co-terephthalate) copolymers were obtained via reaction of post-consumer poly(ethylene terephthalate) flakes and synthesized oligoethylene phthalate resin in the melt phase in the absence of catalyst. The effect of phthalate concentration in polymer on the isothermal crystallization of phthalate substituted poly(ethylene terephthalate) was estimated.Conclusions. The hypothesis about the possibility of using an oligoester modifier to obtain the PET-based copolymer at the high rate and without reducing the molecular weight to values characteristic of a monomer or oligomer has been confirmed. The process can be used to obtain random copolyesters based on post-consumer PET. The phthalate unit concentration increase is followed by decrease in the glass transition temperature, temperature and heat of fusion, and increase in crystallization half-times. Phthalate has a better ability to retard PET crystallization than 2-methyl-1,3-propanediol or furandicarboxylic acid, but is inferior to some of the other modifiers known.

Superparamagnetic iron oxide nanoparticles (SPIONs) have their use approved for the diagnosis/treatment of malignant tumors and can be metabolized by the organism. To prevent embolism caused by these nanoparticles, they need to be coated with biocompatible and non-cytotoxic materials. Here, we synthesized an unsaturated and biocompatible copolyester, poly (globalide-co-ε-caprolactone) (PGlCL), and modified it with the amino acid cysteine (Cys) via a thiol-ene reaction (PGlCLCys). The Cys-modified copolymer presented reduced crystallinity and increased hydrophilicity in comparison to PGlCL, thus being used for the coating of SPIONS (SPION@PGlCLCys). Additionally, cysteine pendant groups at the particle's surface allowed the direct conjugation of (bio)molecules that establish specific interactions with tumor cells (MDA-MB 231). The conjugation of either folic acid (FA) or the anti-cancer drug methotrexate (MTX) was carried out directly on the amine groups of cysteine molecules present in the SPION@PGlCLCys surface (SPION@PGlCLCys_FA and SPION@PGlCLCys_MTX) by carbodiimide-mediated coupling, leading to the formation of amide bonds, with conjugation efficiencies of 62% for FA and 60% for MTX. Then, the release of MTX from the nanoparticle surface was evaluated using a protease at 37 °C in phosphate buffer pH~5.3. It was found that 45% of MTX conjugated to the SPIONs were released after 72 h. Cell viability was measured by MTT assay, and after 72 h, 25% reduction in cell viability of tumor cells was observed. Thus, after a successful conjugation and subsequent triggered release of MTX, we understand that SPION@PGlCLCys has a strong potential to be treated as a model nanoplatform for the development of treatments and diagnosis techniques (or theranostic applications) that can be less aggressive to patients. [ABSTRACT FROM AUTHOR]

This study evaluated the efficacy of different cleaning methods with respect to changes in the color and light transmittance of both rough and smooth thermoformed, copolyester retainer specimens, after staining in different solutions. Four hundred copolyester sheets (Essix ACE) specimens were fabricated over molds with different surface textures, smooth and rough. The specimens were stained in four different solutions (n = 100 per solution) over 28 days; then, each of the four groups of 100 stained specimens was sub-divided into five groups of 20 specimens and subjected to a different destaining solution. The specimens were sub-divided with half subjected to an additional ultrasonic cleaning procedure. Light transmittance and color changes were analyzed using a spectrometer/integrating sphere assembly and a spectrophotometer. Mean difference comparisons were performed using appropriate statistical tests at p = 0.05. All five destaining solutions proved to be effective at removing coffee and tea stains. The surface roughness of the retainer material plays a significant role in the ability of cleaning solutions to remove stains, demonstrating a greater effect on cleaning rough specimens with respect to improvements in light transmittance and greater changes in color. Additionally, an ultrasonic cleaning unit generally enhanced the ability of all five solutions to clean the tea-stained specimens. However, the enhancements were only significant for light transmittance. [ABSTRACT FROM AUTHOR]

In this investigation, a new wholly aromatic random copolyester containing 4,4'-dihydroxybiphenyl, 3,5-dihydroxytoluene and Isophthaloyl chloride was synthesized using the solution polycondensation methodology in the mole ratio 2:1:3 and its solubility along with inherent viscosity were determined. The chemical structure of the copolyester was established by traditional spectroscopic techniques. The physical parameters of the polyester were studied employing WAXD studies and the thermal stability along with phase transitions were investigated employing TGA and DSC data. The morphological features in the polyester were probed using Scanning Electron Microscopy. The anticancer activity of copolyester was verified using HeLa (Cervical carcinoma) cell line employing MTT assay. [ABSTRACT FROM AUTHOR]

The ever-increasing use of plastics, their fossil origin, and especially their persistence in nature have started a wave of new innovations in materials that are renewable, offer the functionalities of plastics, and are biodegradable. One such class of biopolymers, polyhydroxyalkanoates (PHAs), are biosynthesized by numerous microorganisms through the conversion of carbon-rich renewable resources. PHA homo- and heteropolyesters are intracellular products of secondary microbial metabolism. When isolated from microbial biomass, PHA biopolymers mimic the functionalities of many of the top-selling plastics of petrochemical origin, but biodegrade in soil, freshwater, and marine environments, and are both industrial- and home-compostable. Only a handful of PHA biopolymers have been studied in-depth, and five of these reliably match the desired material properties of established fossil plastics. Realizing the positive attributes of PHA biopolymers, several established chemical companies and numerous start-ups, brand owners, and converters have begun to produce and use PHA in a variety of industrial and consumer applications, in what can be described as the emergence of the “PHA industry”. While this positive industrial and commercial relevance of PHA can hardly be described as the first wave in its commercial development, it is nonetheless a very serious one with over 25 companies and start-ups and 30+ brand owners announcing partnerships in PHA production and use. The combined product portfolio of the producing companies is restricted to five types of PHA, namely poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), even though PHAs as a class of polymers offer the potential to generate almost limitless combinations of polymers beneficial to humankind. To date, by varying the co-monomer type and content in these PHA biopolymers, their properties emulate those of the seven top-selling fossil plastics, representing 230 million t of annual plastics production. Capacity expansions of 1.5 million t over the next 5 years have been announced. Policymakers worldwide have taken notice and are encouraging industry to adopt biodegradable and compostable material solutions. This wave of commercialization of PHAs in single-use and in durable applications holds the potential to make the decisive quantum leap in reducing plastic pollution, the depletion of fossil resources, and the emission of greenhouse gases and thus fighting climate change. This review presents setbacks and success stories of the past 40 years and the current commercialization wave of PHA biopolymers, their properties, and their fields of application.

Poly(ethylene-co-isosorbide terephthalate) (PEIT) copolyesters could be used in various applications depending on their ability to crystallize. Moreover, the possibility to carry out solid-state post-condensation (SSP) is conditioned by its ability to sufficiently crystallize. The present study, thus, gives a systematic investigation of isothermal crystallization of these statistical copolyesters with isosorbide contents ranging from 4.8 to 20.8 mol.%. For each copolyester composition, the lowest isothermal half crystallization times and the highest Avrami constant (K) were obtained around 170 °C. Over the range of composition that was studied, both melting points and melting enthalpies decreased with increasing amounts of isosorbide (from 250 to 207 °C and from 55 to 28 J/g, respectively). On the contrary, half crystallization time displayed an exponential increase when increasing isosorbide contents in the studied range. Finally, structural and thermal analysis of PIT homopolyester are reported for the first time, showing that only ET moieties crystallized when PEIT was subjected to isothermal crystallization at 170 °C. [ABSTRACT FROM AUTHOR]

• Addition of phosphonium Ionic Liquid interestingly modifies mechanical properties of PBAT. • Depending on the counter anion, the ionic liquid is miscible or not with PBAT. • AFM nanomechanical mappings highlights the complex structurating mechanism. • Dielectric spectroscopy helps to identify rigid and mobile amorphous phases. The influence of the addition in small amounts (2 wt%) of two phosphonium–based ionic liquids (ILs) on the nanostructuration and mechanical properties of a poly(butylene-adipate- co -terephtalate) (PBAT) matrix was investigated using complementary approaches. Dielectric spectroscopy and nanomechanical characterizations using atomic force microscopy (PeakForce QNM mode, Bruker) were used along X-ray diffraction, differential scanning calorimetry and dynamic mechanical analysis to explain the mechanical (tensile) properties of each system. The semicrystalline matrix was found to have a spherulitic structure, with crystalline lamellae composed of butylene terephtalate units. In one case, the addition of an immiscible phosphonium-phosphinate ionic liquid (il-TMP) to the matrix, inducing a 33% increase of the strain at break, was found via AFM to induce a nodular microstructure with dissipative effects and smooth nodule-matrix interphases. In the other case, a phosphonium-chloride ionic liquid (il-Cl), being miscible in the amorphous phases, increases the chain mobility of the mobile amorphous fraction (MAF) consisting of free polymer chains, while it hinders the relaxation, thus chain movements, of the confined rigid amorphous fraction (RAF). This double effect induced a moderate macroscopic Young's modulus drop (less than −20%) with a +60% increase of the strain at break, and no significant influence on thermal properties. AFM in situ mechanical measurements, along with dielectric spectroscopy, allowed to propose complete mechanisms for the ILs-matrix interactions, highlighting the potential of such additives for the tuning of the properties of polymers. [ABSTRACT FROM AUTHOR]

The main purpose of this study is to highlight the thermal and mechanical characterization of printed copolyester-based polymer. The variety of benefits of this material, such as its food contact compliance and important mechanical properties, have proved to be effective in huge field of applications, including medical sector and packaging uses. However, it has not received much attention for 3D printing processes. As the printing temperature is a key parameter of fused deposition modeling (FDM) process, the present study is started by analyzing its effect on the mechanical properties of printed copolyester under tensile loading. Indeed, the determination of temperature optimal values to print this material with FDM process is done based on tensile properties, including tensile strength, Young's modulus, ultimate tensile and yield strength, ductility and fracture toughness. The fracture properties of printed copolyester are also discussed using “scanning electron microscopy” (SEM). The results indicate a strong effect of the extrusion temperature on tensile properties. In addition, the analysis of copolyester sample microstructure reveals several damage mechanisms within the printed parts that reflect different types of wires fracture form subjected to the same tensile loading.

Together with other so-called “bio-plastics”, Polyhydroxyalkanoates (PHAs) are expected to soon replace established polymers on the plastic market. As a prerequisite, optimized process design is needed to make PHAs attractive in terms of costs and quality. Nowadays, large-scale PHA production relies on discontinuous fed-batch cultivation in huge bioreactors. Such processes presuppose numerous shortcomings such as nonproductive time for reactor revamping, irregular product quality, limited possibility for supply of certain carbon substrates, and, most of all, insufficient productivity. Therefore, single- and multistage continuous PHA biosynthesis is increasingly investigated for production of different types of microbial PHAs; this goes for rather crystalline, thermoplastic PHA homopolyesters as well as for highly flexible PHA copolyesters, and even blocky-structured PHAs consisting of alternating soft and hard segments. Apart from enhanced productivity and constant product quality, chemostat processes can be used to elucidate kinetics of cell growth and PHA formation under constant process conditions. Furthermore, continuous enrichment processes constitute a tool to isolate novel powerful PHA-producing microbial strains adapted to special environmental conditions. The article discusses challenges, potential and case studies for continuous PHA production, and shows up new strategies to further enhance such processes economically by developing unsterile open continuous processes combined with the application of inexpensive carbon feedstocks.

Graphical abstract Highlights • Bio-based poly(ethylene 2,5-furandicarboxylate- co -ε-caprolactone)s (PEFCLs) were prepared via copolymerization. • PEFCL40 had a Young's modulus 1182 ± 80 MPa, a tensile strength 51 ± 3 MPa and an elongation as high as 981 ± 117%. • The modified materials maintained good thermal stability. Abstract A new bio-based copolyesters, poly(ethylene 2,5-furandicarboxylate- co -ε-caprolactone) (PEFCL), were synthesized from 2,5-furandicarboxylic acid, ethylene glycol and ε-caprolactone. The obtained copolyesters were characterized in terms of chemical structures, thermal and mechanical properties. The characterization results of 1H NMR and 13C NMR had confirmed the insertion of lactones units in PEF chains, all PEFCL copolyesters showed random microstructures. These bio-based copolymers were amorphous and had one glass transition temperature decreased as increasing the CL content. The thermal stability of PEFCL is slightly lower than PEF. Tensile testing revealed that introduction of ε-caprolactone into PEF chains impart PEFCL with excellent mechanical performance, typically, PEFCL40 had a Young's modulus 1182 ± 80 MPa, a tensile strength 51 ± 3 MPa and an elongation as high as 981 ± 117%. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • High temperature to lead copolyester printability with fused deposition modelling. • Low stiffness but acceptable tensile strength of 3D printed copolyester. • Failure patterns of printed copolyester reveal combination of three damage mechanisms. Abstract 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 inhomogeneous change in the filament morphology at the rupture point. [ABSTRACT FROM AUTHOR]

Poly(ethylene-co-isosorbide terephthalate) (PEIT) copolyesters could be used in various applications depending on their ability to crystallize. Moreover, the possibility to carry out solid-state post-condensation (SSP) is conditioned by its ability to sufficiently crystallize. The present study, thus, gives a systematic investigation of isothermal crystallization of these statistical copolyesters with isosorbide contents ranging from 4.8 to 20.8 mol.%. For each copolyester composition, the lowest isothermal half crystallization times and the highest Avrami constant (K) were obtained around 170 °C. Over the range of composition that was studied, both melting points and melting enthalpies decreased with increasing amounts of isosorbide (from 250 to 207 °C and from 55 to 28 J/g, respectively). On the contrary, half crystallization time displayed an exponential increase when increasing isosorbide contents in the studied range. Finally, structural and thermal analysis of PIT homopolyester are reported for the first time, showing that only ET moieties crystallized when PEIT was subjected to isothermal crystallization at 170 °C.

This paper reports a hollow copolyester fiber modified with polyethylene glycol and sodium-5-sulfo-bis-(hydroxyethyl)-isophthalate, abbreviated as ECDP-H, which has the potential to be a replacement for cotton. The objective evaluation of luster (contrast glossiness) and Kawabata Evaluation System for Fabrics (KES-F) (four Primary Hand Parameters and the Total Hand) of ECDP-H, PET and cotton fabrics are studied in order to investigate the cotton-like appearance of the ECDP-H. The results of moisture regain and dynamic moisture absorption values obtained indicate that the hydrophilicity of the ECDP-H fabric is better than that of PET fabric. The thermo-physiological performance for three fabrics is determined using air and water vapor permeability, wicking, warm-cooling feeling, thermal resistance and vapor resistance. The results show that the ECDP-H fabric has better hand and comfort properties than cotton. [ABSTRACT FROM AUTHOR]

Different (co)polyesters, poly(1,4-butylene succinate- ran -2,3-butylene succinate) (PBB’S), were enzymatically copolymerized at different 1,4-butanediol (1,4-BDO)/2,3-butanediol (2,3-BDO) molar ratios, with immobilized Candida antarctica lipase B (CALB). The synthesized macromolecular architectures were characterized by NMR, SEC, FTIR, WAXS, MALDI-TOF MS, DSC, TGA and specific optical rotation. Based on an optimized process, PBB’S copolyesters were synthesized in high yield. A random distribution between both BDOs was obtained along the chain. M w ‾ decreased with increasing 2,3-BDO content, from 26 to 6 kg/mol. The specific optical rotation decreased linearly with decreasing 2,3-BDO content, and can be used as a characterization technique to determine PBB’S composition. DSC results showed that an increase in 2,3-BDO content raised the Tg and reduced the degree of crystallinity, leading to amorphous materials for 2,3-BDO content higher than 47 mol.%. Synthesized copolyesters exhibited a good thermal stability, higher than 250 °C, with a degradation profile depending on the 1,4-BDO/2,3-BDO ratio. [ABSTRACT FROM AUTHOR]

Devulcanized rubber (DR) was prepared from used truck tires via thermo-chemical devulcanization. Effects of devulcanizing reaction time and temperature were studied, and the DR contained higher sol fraction but had lower crosslink density than un-devulcanized rubber (UDR). Furthermore, the soluble fraction (sol fraction) increased with devulcanizing time and temperature. Devulcanizing for 4 min at 180 °C was chosen as the most efficient alternative. Then, thermoplastic vulcanizates (TPVs) from blends of copolyester (COPE) with two alternative types of recycled rubber (i.e., DR and UDR) were prepared and their mechanical, morphological, rheological, thermal and swelling properties were investigated. It was found that the dynamically cured DR/COPE blends exhibited higher mechanical and thermal resistance than the dynamically cured UDR/COPE blends. Furthermore, the complex viscosity and storage modulus of the dynamically cured DR/COPE blends decreased with devulcanizing time, due to breakdown of the rubber network and the carbon main chains in rubber molecules. In addition, phase separated micron-sized vulcanized rubber domains were finely dispersed in the COPE matrix, and their size correlated well with the mechanical strength and other related properties. However, the rubber domains agglomerated with excessive devulcanization, causing inferior mechanical strength. [ABSTRACT FROM AUTHOR]

This editorial paper provides a synopsis of the contributions to the Bioengineering special issue “Advances in Polyhydroxyalkanoate (PHA) Production”. It illustrates the embedding of the issue’s individual research articles in the current global research and development landscape related to polyhydroxyalkanoates (PHA). The article shows how these articles are interrelated to each other, reflecting the entire PHA process chain including strain selection, metabolic and genetic considerations, feedstock evaluation, fermentation regimes, process engineering, and polymer processing towards high-value marketable products.

The problem of incorporating plastics into the environment will be aggravating, both regarding its scale and kind of these materials. Investigations were carried out using aliphatic-aromatic copolyester poly (succinate-co-glutarate-co-adipate-co-terephthalate 1,4-butylene) with addition of fatty acid dimers. The work aimed to determine the effect of composting the copolyester with plant biomass on changes of fractional composition of humus substances and their stability. Copolyester was supplemented to the biomass in the form of a nonwoven fabric in two doses. It constituted 8 and 16% of the dry mass of the composted substrates. The composting process was run within two ranges of ambient temperature 25-30°C and 40-45°C. After the completion of this process, the degree of material maturing was assessed using manometric methods and the carbon content was analysed in the individual organic matter fractions. On the basis of cumulated respiratory activity AT4 a lack of composted material activity was revealed in the higher temperatures of the process. However, in the objects where copolyester was transformed in the lower temperatures this activity was considerably diversified. Adding copolyester to the composted biomass led to a diversification of the Cha : Cfa ratio. The values of Cha : Cfa ratio most approximating 1.5, ie the value regarded as optimal, were registered in the object, where copolyester supplement constituted 16% and the plant biomass was maintained within the 40-45°C temperature range. [ABSTRACT FROM AUTHOR]

Liquefied wood (LW) prepared in a microwave process was applied as a novel; inexpensive precursor feedstock for incorporation of (R)-3-hydroxyvalerate (3HV) into polyhydroxyalkanoate (PHA) biopolyesters in order to improve the biopolyester's material quality; Cupriavidus necator was applied as microbial production strain. For proof of concept, pre-experiments were carried out on a shake flask scale using different mixtures of glucose and LW as carbon source. The results indicate that LW definitely acts as a 3HV precursor, but, at the same time, displays toxic effects on C. necator at concentrations exceeding 10 g/L. Based on these findings, PHA biosynthesis under controlled conditions was performed using a fed-batch feeding regime on a bioreactor scale. As major outcome, a poly(3HB-co-0.8%-3HV) copolyester was obtained displaying a desired high molar mass of Mw = 5.39 × 105 g/mol at low molar-mass dispersity (ĐM of 1.53), a degree of crystallinity(Xc) of 62.1%, and melting temperature Tm (176.3 °C) slightly lower than values reported for poly([R]-3-hydroxybutyrate) (PHB) homopolyester produced by C. necator; thus, the produced biopolyester is expected to be more suitable for polymer processing purposes. [ABSTRACT FROM AUTHOR]

Poly(hydroxyalkanoates) (PHAs) can be synthesized by adopting different microbial fermentation strategies, of which submerged fermentation has been exploited largely. In the past few years, solid-state fermentation (SSF) has been reassessed as an alternative to submerged fermentation, and could be a possible strategy for the cost-effective production of PHAs. The capital investment for SSF is usually lower than that of submerged fermentation and the cost of raw materials for SSF would be cheap, since it uses waste agricultural residues. These positive factors make SSF a potential technique for PHAs production. However, this method is still too immature for commercialization. The major drawback to address is the proper maintenance of the culture conditions under SSF. The present review discusses the current developments in solid-state fermentation for the production of PHAs and addresses the various issues for its commercialization. [ABSTRACT FROM AUTHOR]

The halobacterium Haloferax mediterranei was used to study the production of two types of biopolymers: The biopolyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was accumulated as intracellular granules, whereas an extracelluar polysaccharide was excreted in parallel to biopolyester synthesis. After production, microbial re-use and degradation of these polymers under different conditions were investigated to assess the requirements for handling the product-rich fermentation broth prior to the downstream processing for product recovery. Degradation kinetics of the polymers and the impact of different storage conditions on molar mass of PHBV were studied. It turned out that the biotechnological fermentation process can be run without any sterility precautions. No major product losses were observed without pasteurization of fermentation broth after the stop of fermentation. In addition, neither PHBV nor EPS are re-utilized by the cells for biomass formation even if the culture is maintained under conditions of carbon starvation for an extended time. [ABSTRACT FROM AUTHOR]