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This communication reports on the continuous biohydrogen production by Thermotoga neapolitana cells immobilized on a stable cationic hydrogel bearing amine groups. This hydrogel was designed to perform two functional activities: to promote adhesion of T. neapolitana cells, and to buffer pH changes in the bacterial cultures. Repeated fed-batch cultures showed an average hydrogen production rate and yield of 50.6 mL L-1 h(-1) and 3.3 mol H-2/mol glucose, respectively. To the best of our knowledge, this is the first report detailing the immobilization of this bacterial strain on a polymeric support.

Hydroxyapatite (Ca-10(PO4)(6)(OH)(2)) is one of the most biocompatible ceramics because it is similar to the mineral constituents of human bone and teeth. Composites of hydroxyapatite (HA) and biodegradable polymers such as polycaprolactone (PCL) are interesting materials for medical applications, especially for bone replacement. With the aim to improve the properties of biodegradable polyester-based devices, we have prepared and characterized novel composites made of polycaprolactone and natural or synthetic hydroxyapatite. The composites were screened for cytocompatibility by a direct contact method, in view of the future application of these hydroxyapatite filled PCL polymers as scaffolds for bone engineering. Primary cultures of human bone marrow mesenchymal stem cells (MSC) were selected as the most appropriate models to study the in vitro performance of these materials. The results showed that all materials have good biocompatibility and allow expression of the osteoblastic features. Scanning electron microscopy provided direct evidence of intense cell adhesion and proliferation on the tested materials.

A binary blend of poly(L-lactide) (PLLA) and poly(e-caprolactone) (PCL) of composition 70:30 by weight was prepared using a twin screw miniextruder and investigated by differential scanning calorimetry (DSC), optical microscopy and sanning electron microscopy (SEM). Thernary 70:30:2 blends were also obtained by adding either a diblock copolymer of PLLA-PCL-PLLA copolymer as a third component. Optical microscopy revealed that the domain size of dispersed PCL domains is reduced by one order of magnitude in the presence of both copolymers. SEM confirmed the strong reduction in particle size upon the addition of the copolymers, with an indication of an enhanced emulsifying effect in the case of the PLLA-PEO copolymer. These results are analyzed on the basis of solubility parameters of the blend components.

A series of conjugated aromatic polyoxadiazoles was prepared by cyclization with phosphorus oxychloride of the corresponding polyhydrazides. These last ones were obtained by solution polycondensation of 2-alkoxy-terephthaloyl dihydrazides with 2-alkoxy-terephthaloyl dichlorides. Homogeneous thin films of such a material were prepared by the spin-coating technique. Films spun on silica fused were characterized by spectroscopic analysis in the whole ultraviolet–visible–near infrared (UV–VIS–NIR) range (200–2500 nm). Spectra in transmittance show a peculiar and very interesting behavior of these materials: they absorb all the radiation in the UV–VIS range until 425 nm, where sharply the transmission becomes more than 90% until the IR range. Some films spun on silica fused were used as planar waveguides and studies on light propagation in these films were done. The optical constant (refractive index) and the film thickness has been measured using optical mode guiding. It has then been prepared a device consisting of the said polymer sandwiched between two electrodes on top of a glass substrate. The electron conductivity of the polymer, calculated by current–voltage measurements using Al as the electron injecting contacts, has been found to be higher than that of poly( p -phenylene-1,3,4-oxadiazole).

In this work, a polyphenol-containing extract from winery bio-waste (EP) has been used as additive to tailor Mater-Bi properties. EP was able to efficiently modulate both polymer processing and mechanical, thermal and biodegradation properties. EP decreased the melt viscosity, behaved as a Mater-Bi plasticizer and delayed the Mater-Bi crosslinking process occurring upon thermal aging. Finally, the biodisintegration rate of doped Mater-Bi decreased, thus indicating that EP interfered with the microbial digestion of the polymer films.

A synthetic approach for the realisation of lifetime controlled biodegradable films is described starting from existing biodegradable polymers. Polyvinylalcohol (PVOH) chains are bridged through functionalised polycaprolactone (PCL) crosslinks directly during extrusion and film lamination. The resulting films are water resistant and their degradation may start only when buried in the soil due to microbial attack of the PCL bridges. The influence of blend composition on the mechanical properties and water sensitivity has been analysed. A thermal annealing is necessary after extrusion in order to complete the crosslinking of the obtained film. A mathematical model has been applied on the film to simulate their “greenhouse” effect. It was found that such films, when used as mulching film in agriculture, have a very interesting thermal response allowing temperatures inside the soil of 40–50°C, comparable to well known non biodegradable mulching films.

L'obiettivo iniziale della proposta di progetto era valutare come migliorare, controllare e ridurre al minimo gli impatti negativi delle acque saline sulla resa delle colture e la struttura del suolo, migliorando nel contempo la qualità e il valore di mercato dei prodotti. Obiettivi specifici erano: 1)valutazione della gestione irrigua differenziata in termini di restituzione dell'acqua, risposta della resa, effetti sulla pianta e sulla qualità del suolo. 2)Valutazione delle potenzialità della pacciamatura a spruzzo come potenziale sostituzione dell'attale sistema tradizionale non degradabile. Gli obiettivi di cui sopra durante il corso del progetto sono stati cambiati per cause dipendenti da vincoli strutturali e logistici che il partner cinese si è trovato a fronteggiare dopo l'approvazione del progetto che hanno determinato forti ritardi e successivamente l'impossibilità di mantenere lo schema di programma prefissato. I forti vincoli erano particolarmente causati dalla localizzazione della stazione sperimentale e da altre difficoltà. Inoltre a queste problematiche elencate due annate climatiche particolarmente siccitose hanno reso impossibile il buon esito del progetto. In abbinamento a tale attività abbiamo concluso nel corso del 2012 e del 2013 due pubblicazioni sulla campagna di rilievo del triennio precedente che sono citati nei prodotti. Visti i notevoli problemi di due anni (2011-2012) consecutivi, si è concordato con i colleghi di cambiare il tipo di approccio, valutando un discorso di "Biorimediation" e "phytodepuration ". Al momento sono state selezionate 22 specie appartenenti alle famiglie delle Poaceae, Tamaricaceae, Chenopodiaceae per le quali si sono iniziate delle prove di germinabilità nell'ambiente di studio

A lignin-rich residue (LRR) obtained as a by-product from the fermentative bioethanol production process, and commercial alkali lignin (AL), were used as fillers for the preparation of bio-based blends and composites with poly(3-hydrobutyrate) (PHB). Chemical characterization of LRR demonstrated that the filler contained sugar residues. Rheological and thermal characterization of the blends demonstrated that LRR did not affect thermal stability of PHB, while AL had a strong pro-degrading effect. Addition of suitable amounts of LRR dramatically affected the rheological behavior of the polymer melt, suggesting that the additive can modify polymer processability. LRR was also a heterogeneous nucleating agent, potentially able to control the physical aging of PHB. Lower resilience and elongation at break values were found for the biocomposites, due to the poor interfacial adhesion between filler and matrix. Biodegradation behavior of the composites was qualitatively assessed by analyzing the surface of soil buried films. Significant surface degradation was observed for PHB, while the process was retarded at high filler concentration, as LRR inhibited hydrolytic and biotic polymer degradation. The reported results demonstrated the feasibility of the conversion of an agro-industrial by-product into a bio-resource in an environmentally friendly and cost-effective way. © 2014 Elsevier B.V.

Poly(lactic acid) (PLA) is a biodegradable polyester produced from renewable resources. Similar to other biodegradable polyesters, PLA displays crystal polymorphism. Only two crystal modifications grow upon usual processing conditions: ? crystals at high crystallization temperature and ?' crystals at low temperatures. PLA films containing different ratios of ?'?and ? crystals were prepared by annealing quenched PLA at different temperatures. It was found that the polymorphic structure of PLA significantly affects its mechanical, thermal and barrier properties. The ? crystal modification provides a better barrier to water vapor and a higher Young's modulus, compared to films containing ?' form, but a lower elongation at break. The varied barrier and mechanical properties were correlated to the different packing of PLA chains in the two analyzed polymorphs, as well as to the morphology of PLA spherulitic superstructures. Quantitative analysis with conventional and temperature-modulated calorimetry revealed a three-phase structure of PLA composed of a crystal phase and two amorphous fractions with different mobility, for all the analyzed thermal histories. A higher coupling of the amorphous chain segments with the crystal phase was found in the presence of ? crystals, probably due to the slightly larger lattice dimensions and the looser arrangements of PLA chains in the ?' structure. Moreover, the influence of chain structure of PLA on ? / ?' polymorphism was studied. The monomer, lactic acid, has two optically active forms called L-lactic acid and D-lactic acid. Commercial poly(lactic acid) grades are usually based on an L-rich mixture, as the majority of bacteria used in fermentation processes mainly produce L-lactic acid, and typically comprise a minimum of 1-2% D- units. Incorporation of D-lactic acid monomer leads to a decrease of the overall crystallization rate of PLA, as well as of the rate of spherulite growth (G) of both the crystal modifications. The relative crystallization rates of ? and ?' forms are highly affected by stereoregularity, especially in the PLA grades that have a high crystallization rate. A high D-lactic acid content results not only in an overall slower crystal growth, but also in a varied temperature range where each of the two crystal modifications prevail, with a shift to lower temperatures of both the maxima of the G vs. temperature plots, indicating that inclusion of D-lactic acid units in the PLA chain affects crystallization rate of both ? and ?' crystal modifications.

Immiscible binary blends of poly( l , l -lactide) (PLLA), and poly(e-caprolactone) (PCL), with 90/10, 80/20 and 70/30 wt% compositions, as well as ternary PLLA/PCL blends containing 0.5–5 wt% of a triblock PLLA/PCL/PLLA copolymer, were obtained by melt mixing using a twin screw extruder. Optical microscopy investigation of binary blends revealed the immiscibility of the components. The thermal behaviour of the blends was investigated by DSC and DMTA and compared with that of pure PLLA. The PLLA crystallization rate was enhanced in the presence of PCL domains. Morphological analysis of the cryofractured and etched–smoothed surfaces was carried out by SEM on both binary and ternary blends. A dimensional analysis of the PCL domains in binary and ternary blends was also performed in order to evaluate the influence of the presence of the triblock copolymer on the dispersion mode of PCL in the PLLA matrix.

A series of copolyesters (PE) of low molecular weight containing propyloxy-substituted aromatic ring and/or ethylenic sequences between aromatic units were prepared by melt polycondensation between corresponding diacids and diacetates, and used as precursor of poly(ester-co-polyhydrazide) (PEH) new copolymers. The PEs showed to have thermotropic properties, with transition temperatures which depend on the chemical composition and with a good interval of stability of the mesophase. The corresponding PEHs were obtained by high-temperature polycondensation of carboxyl-terminated PEs with terephthalic dihydrazide. The PEHs showed as well a stable mesophase in the melt, and improved thermal stability respect to polyesters. All the polymers were characterized by elemental analysis, inherent viscosity, infrared and 13 C solid state NMR spectroscopy, thermal and thermogravimetric analysis and optical microscopy. Fibers of PEHs were obtained by melt-spinning and characterized by WAXS analysis.

A simple method for evaluating polymeric films to be employed in the agricultural field is proposed. The method consists of optical characterization (spectral analysis) and numerical elaboration of the experimental data on the basis of a theoretical model, in order to predict the optical behavior of organic materials, which determines the temperature variations inside a physical system. Results for new biodegradable materials for mulching and soil solarization are presented and compared with the traditional materials. Our work demonstrates the validity of the proposed methodological approach and confirms the potential of the considered materials for use in agriculture.

Chemical physical analysis, photo-oxidative stability and lipid oxidation of innovative polymeric films based on blends of nylon 6 and ethylene-co-vinyl alcohol for use in food packaging have been investigated. Thermal mechanical analysis showed that the presence of an interfacial agent in the blend stabilized the films towards the action of permeants. Synergistic effects of the interfacial agent are reported with respect to UV photostability. Peroxide value (PV) was used to follow the oxidation of the olive oil, and for this parameter also the influence of the interfacial agent was clearly detected. Copyright © 2001 John Wiley & Sons, Ltd.

Biodegradable blend films containing sodium alginate, polyvinyl alcohol and glycerol, for agricultural applications, were prepared by casting of aqueous solutions. Since the mechanical properties of alginate are not suitable for agricultural applications, the addition of polyvinyl alcohol and glycerol was necessary in order to improve some mechanical parameters like the strain at break. The interaction between different components was studied by thermogravimetric analysis and DSC, while mechanical parameters and the transmittance in the IR region were investigated in order to identify the compositions with suitable properties for application in agriculture.

A preliminary study on the possibility to use the copolymer poly[(ethylene terephthalate)-co-(e-caprolactone)] as a compatibilising agent in blends of high density polyethylene (HDPE) and poly(ethylene terephtalate) (PET) is reported. The copolymer was synthesised by polycondensation of low-molecular weight PCL precursors, previously end-capped with reactive isocyanate groups, and oligomers of PET obtained from PET waste through a controlled depolymerisation procedure. HDPE/PET blends at a composition of 70/30 w/w with and without the addition of 10 wt.-% of compatibiliser were prepared in a single-screw mixer extruder. The effect of compatibiliser waas evaluated by studying the thermal, dynamic-mechanical and mechanical properties and the morphology of the blends. The compatibiliser was found to be a good emulsifying agent from a morphological point of view. Nevertheless, the mechanical properties of the blend were not improved by the addition of the compatibiliser.

Segmented poly(ether–ester–amide)s (PEEAs) were obtained from sebacoyl chloride (SEB), α,ω-hydroxyl terminated poly( l , l -lactide) (PLLA) or PLLA–PEG–PLLA macromers and the hydrophilic diamines 4,7,10-trioxa-1,13-tridecanediamine ( 1 ) and 3,6,9,12,15-pentoxa-1,17-heptadecanediamine ( 2 ) or diamide–diamines derived from 1 and 2 by inserting Gly-Phe or Gly-Val-Phe sequences. The molar ratio macromer/SEB/diamine was 1/2/1. The PEEAs were characterized by i.r. and 1 H n.m.r spectroscopy and S.E.C. They are soluble in polar organic solvents and insoluble in water, but show equilibrium water absorptions up to 21.0% by wt. All PEEAs are semicrystalline, as shown by d.s.c. and WAXS techniques, with T m s ranging from 110 to 135°C. D.s.c. and d.m.t.a. showed a single T g in the temperature range 31–53°C. Evidence of microphase separation was obtained only for aminoacids containing PEEAs by t.e.m.. Biocompatibily was assessed for selected polymers checking the viability and growth of Caco-2 cells on polymer films.

Poly(L-lactic) (PLLA)-based containing poly(methyl methacrylate) (PMMA) as dispersed phase are reported in the present paper. The blends are prepared by reactive (NR-type blends) as well as non reactive (NR-type blends) methodologies, according to the preparation of the blends either polymerizing the acrylic monomer in the presence of PLLA or melt mixing the two polymers (PLLA and PMMA) in bulk. Thermal as well as morphological studied performed on both R and NR blends have revealed an intimate dispersion of PLLA and PMMA. Unlikely previous studies carried out on different aliphatic polyesters but following similar chemical approach, mechanical tests on the PLLA-type blends. The results are interpreted on the basis of extensive cross-linking of the system caused by the high sensitivity of PPLA to radical attack. The copolymeric phase formed during the reactive blending is isolated and characterised by NMR technique.

With the aim of exploring possible application of the concept of blend compatibilisation into the field of biodegradable membranes, a study of the influence of random copolymer poly(D,L-lactide-co-∈-caprolactone) on the properties of corresponding homopolymer blends has been conducted. Blends of plain homopolymers and blends containing 5 and 10 wt% of a copolymer of suitable composition have been prepared in the melt and characterised for their molecular interactions using thermal, dynamic-mechanical, mechanical (tensile tests) and morphological analyses. The blends are characterised by a good dispersion of the poly-∈-caprolactone (PCL) minor phase into the poly(D,L-lactic acid) (PDLLA) matrix and better mechanical properties compared to plain PDLLA, and such characteristics further improve when adding the copolymer. Microporous blend membranes consisting of PDLLA and PCL were then prepared by a phase inversion method and characterised by scanning electron microscopy. The addition of compatibilising agent led to a highly homogeneous structure, while in absence of compatibiliser a clear phase separation occurred.

The thermal oxidative stability and the effect of water on gas transport and mechanical properties of blends of polyamide 6 (PA6) with ethylene-co-vinyl alcohol (EVOH) and EVOH modified with carboxyl groups (EVOH-COOH) have been investigated. The presence of EVOH reduces water vapor and oxygen gas permeability of polyamide, as well as small amounts of EVOH-COOH further improve barrier properties, especially to oxygen. This has been explained in terms of improved interactions of the blend constituents in the amorphous phase, due to ionic linkages between the polyamide amino groups and the carboxyls of modified EVOH. The permeation to gases was found to increase with the amount of sorbed water. The morphology of the samples was found to have an effect on barrier properties, as the presence of EVOH causes the PA6 α crystalline form to increase, lowering the permeability to oxygen and water vapor. Mechanical properties are strongly affected by water sorption, as tensile modulus and strength decrease with increasing water content. Chemiluminescence (CL), infrared spectroscopy (FTIR), and tensile test were employed in order to assess the correlation between chemical composition and the thermal oxidative stability of the films aged at 110 °C in air. CL experiments suggest that the presence of EVOH and EVOH-COOH efficiently inhibits the formation of peroxidized species during the processing, and increases the thermal oxidative stability of the films. Infrared spectroscopy showed a build-up of carbonyl absorption in the range 1700–1780 cm−1, due to the formation of oxidation products, which is greater in the case of the pure polymer. Tensile tests on films revealed a reduction in ductility as a result of ageing for neat PA6, whereas in comparison the blends exhibit a far better long-term stability. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 840–849, 2007

In this work, the relationships between composition and properties of Ny6/EVOH system were examined by means of several techniques and the results were interpreted in terms of level of compatibility. Blends of different ratio of Ny6 and EVOH have been processed in a laboratory-based film blowing extrusion apparatus. Rheologi- cal measurements, FTIR and morphological analysis, and thermal and mechanical properties were carried out. Peculiar rheological, thermal, and mechanical behaviors were observed for the blend containing 25% by weight of EVOH. At this composition, FTIR analysis has pointed out that a minimum in molecular motion is achieved as a consequence of a maximum interaction of the polar groups (amide groups of Ny6 and hydroxyl groups of EVOH) involved. Moreover, gas permeability measurements on the blown films have been performed at T 5 30°C. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2445-2455, 1999

Novel aromatic poly(etheraroylhydrazides), PEHZ, incorporating a methylenic sequence (with number of -CH 2 -units m = 2, 4, 6, 8, 10, 12) in the main chain, have been obtained by solution polycondensation and characterized with several techniques. In particular, Differential Scanning Calorimetry (DSC) and Wide Angle X-ray Scattering (WAXS) gave interesting results. The complex thermal behavior and the lattice parameters of these linear polyhydrazides are a function of the number of methylene units present in the flexible segment. The relationships we found suggest a model: a polymer with disorder in aliphatic segment layers while preserving chain periodicity, that is the classical model of conformationally disordered crystalline polymer.

Blends of poly-e-caproIactone (PCL) and poly-β-hydroxybutyrate (PHB) were prepared by mixing the two polymers in the presence of dicumylperoxide (DCPO) in solution of chlorobenzene. Similarly blends were obtained by mixing the two polymers with no peroxide added. The blends were prepared in a break of composition, from 85% wt PHB/15% wt PCL to 15% wt PHB/85% wt PCL, respectively. Also pure polymers were reacted with DCPO in the same way of the blends. Thermal (DSC), spectroscopic, mechanical (tensile tests) and morphological SEM)analyses were performed on the blends and on the pure polymers. Significant differences were found in the chemical-physical characteristics of the blends with and without peroxide.

Blends of nylon 6 (Ny6) with ethylene-co-vinyl alcohol (EVOH) and EVOH modified with the introduction of carboxyl groups (EVOH–COOH) have been studied by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and dynamic-mechanical thermal analysis. The thermal and thermomechanical analyses of the blends show that the melting, crystallization, and relaxational behavior are affected by the blend composition and the presence of carboxyl groups on the EVOH chains. Nevertheless, microscopic and thermal investigations demonstrate the biphasic nature of the two-blend systems. Selective solvent extraction of the EVOH or EVOH–COOH phase in their blends and Fourier transform infrared analysis of the residual products indicates the occurrence of ionic linkages between the amino groups of the polyamide and the carboxyl groups of the modified EVOH, whereas specific interactions are evidenced for Ny6/EVOH blends. Tests performed on extruded Ny6/EVOH films show that the addition of EVOH effectively reduces the gas permeability of Nylon, whereas the addition of small amounts of EVOH–COOH helps to control and stabilize melt rheology. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 637–648, 1998

Poly(L-lactic acid) is a biocompatible polyester, semicrystalline, thermoplastic, with low versatility in mechanical properties. To overcome this problem, a reactive blending procedure was performed by grafting an acrylic rubber, n-butyl acrylate, via water suspension polymerization onto poly(L-lactic acid) dissolved in an organic solvent. It was possible to isolate the copolymeric phase formed from the two polymers and characterize it by using NMR and DSC techniques. Mechanical tests on blends gave no satisfactory response, probably because the rubbery phase is composed essentially of viscous linear macromolecules, not able to perform elastic properties. Work is in progress to modify the synthetic pathway to incorporate diacrylates in order to realize a rubbery phase at least partially cross-linked. Poly(L-milchsaure) ist ein biokompatibler, semikristalliner, thermoplastischer Polyester mit ungunstigen mechanischen Eigenschaften. Daher wurde in einem “reactive blending”-Prozes ein Acrylkautschuk, n-Butylacrylat, mittels einer Suspensionspolymerisation in Wasser auf in einem organischen Losungsmittel geloste Poly(L-milchsaure) gepfropft. Die gebildeten Copolymeren konnten isoliert und durch NMR-Spektroskopie und DSC-Messungen charakterisiert werden. Die Untersuchung der mechanischen Eigenschaften ergab keine befriedigenden Ergebnisse, weil die Kautschukphase wahrscheinlich aus viskosen linearen Makromolekulen besteht und daher keine elastischen Eigenschaften besitzt. In weiteren Arbeiten soll der Syntheseweg so modifiziert werden, das durch den Einbau von Diacrylaten eine zumindest partielle Vernetzung der Kautschukphase erreicht wird.

An ethylene/vinyl alcohol co-polymer (EVOH) has been chemically modified to induce the formation of ionic clusters. ‐COOH containing pendant groups have been grafted on the polymer backbone and subsequently have been partially or totally salified. The structure of this class of polymers is expected to be less sensitive to the effect of water vapour if ionic concentration is above a threshold value which guarantees the formation of ionic aggregates. Moreover, the presence of ionic couples should guarantee an increased compatibility towards other polymers if compared to EVOH. Water vapour transport properties of functionalized EVOHs have been determined in order to assess the effect of chemical modifications both on water barrier properties and on sensitivity of polymer structure to sorbed water. Water vapour sorption tests have been performed at 358C at several water vapour activities determining both water sorption isotherms and diffusivities. This is a preliminary study on this new class of materials aimed to assess the possible replacement of EVOH films (or EVOH containing multilayer films) with films based on such polymers (or their blends with other polymers) which should be characterized by a higher resistance to ‘retorting’ conditions. © 1997 by John Wiley & Sons, Ltd.

Recycling of polyethyleneterephthalate (PET) bottles for soft drinks is accomplished by depolymerization through glycolysis. Obtained intermediates are reacted with mixtures of saturated and unsaturated acids to obtain unsaturated polyesters (UP) suitable for use as a matrix for fibre-reinforced thermosetting composites. The influence of chemical structure of glycols on the chemo-rheological behaviour of resins, has been verified. By using di-ethylene glycol, the behaviour of the resulting UP closely resembles that of UP obtained from virgin monomers. Moreover, composite sheets containing UP developed in the present research, show enhanced toughness if compared with the analogous composite made of virgin UP resin.

The use of plastic mulching films in horticulture causes the serious drawback of huge amount of wastes to be disposed of at the end of their lifetime. Several pre-competitive research products based on raw materials coming from renewable sources were recently developed to be used as biodegradable materials for soil mulching. Biodegradable materials are designed in order both to retain their mechanical and physical properties during their using time and to degrade at the end of their lifetime. These materials can be integrated directly in the soil in order to biodegrade because the bacterial flora transforms them in carbon dioxide or methane, water and biomass. The innovative materials can be obtained using natural polymers, such as starch, cellulose, chitosan, alginate and glucomannan. Biodegradable extruded mulching films were performed by means of thermo-plasticizing process. Spray mulch coatings were realized directly in field, by spraying water solutions based on natural polysaccharides, thus covering the cultivated soil with a protective thin geo-membrane. In this paper an overview on the formulation development, processing understanding, field performance, mechanical and radiometric properties of these innovative materials for soil mulching is presented. In field the biodegradable mulching films showed suitable mechanical properties if compared to the low density polyethylene films. The radiometric properties and their effect on the temperature condition and on weed control in the mulched soil were evaluated too. At the end of their lifetime the biodegradable materials were shattered and buried into the soil together with plants.

Wastes and by-products of agro-food industries and paper–textile manufacturing companies, such as tomato peels and seeds, and hemp, were glued with sodium alginate in order to produce biodegradable pots for plant transplanting in agriculture, thus aiming both to reduce such wastes and also to fight the accumulation of plastic pot wastes produced in plant nurseries. Laboratory tests performed on polysaccharide films and biocomposites based sheets prepared with the same materials developed for preparing the pots, were carried out in order to understand the chemico-physical correlations between resin, ionic crosslinking agent, reinforcing fibres and water. To this aim, mechanical tests, water vapour permeability tests, water up-take evaluations and morphological analysis were carried out. It was found a strong physical interaction between sodium alginate and calcium ions in the development of a three-dimensional network. The crosslinked structure was able to physically entrap the reinforcement fibres by means of hydrogen bonding, as evidenced by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. SEM analysis performed on fracture surfaces of the biocomposites evidenced that the fibres were well embedded inside the three-dimensional network, even if their dispersion needed some improvements; EDS analysis revealed the presence of calcium in rather all the selected internal micro-zones, thus suggesting a well structured network. In order to assess the agronomic performance of the novel biodegradable pots in seedling transplanting activity, the pots were tested in real field condition during 2009 at the experimental farm of the University of Bari, Italy. From the analysis of the young plants transplanted in the field, it was inferred that the biodegradable containers had enhanced the roots plants development and the plant growing, avoiding transplant shock and root deformation. After the using time, they completely degraded into the soil within 2 weeks.

Reaction injection moulding of blend samples of poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV) and poly-e-caprolactone (PCL) has been performed in the presence of peroxide. The blends are compared to mechanical PHBV/PCL blends obtained in the absence of peroxides. Differences in chemical physical and mechanical properties are interpreted on the basis of intergrafted species present in the peroxide-treated blends. The obtained blends are proposed as versatile materials for applications for bioresorbable prostheses.

Novel poly(etheraroyl-co-terephthal)hydrazides with liquid crystalline (LC) behaviour, synthesized by solution polycondensation followed by non-solvent coagulation in water, have been characterized by means of Fourier Transform infrared (FT-i.r.), differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS) techniques. DSC thermograms and WAXS intensity profiles of “as polymerized” and coagulated homo- and copolymers are strongly dependent upon the molecular structure and constitution of the polymers: the poly(etheraroyl-hydrazide) homopolymer shows an LC behaviour and such a characteristic is maintained in copolymers with low content of terephthaloyldichloride comonomer, while a further increase in comonomer content attenuates this LC attitude. Annealing treatments on “as polymerized” and coagulated copolymers are able to transform the LC phase “metastable at room temperature” into crystalline and/or amorphous phases.

A novel polymeric material, a poly(methylmethacrylate) (PMMA)/ethylene-co-vinylacerate (EVA) blend, is presented. The blend shows outstanding impact behaviour, at the same level as that of commercially-available ultra-tough PMMA. Moreover, transparency is retained with a transparent-to-opaque transition at about 50°C. The authors show the behaviour of the optical transmission as a function of the temperature, and measure some physical properties of this material. An attempt is made to correlate the thermo-optical behaviour to the variation, across the transition, of fundamental parameters, such as the melting of sub-included rubber particles, the refractive indices of PMMA and EVA, and the particular morphology of the blend. The latter is very interesting, as the rubber particles, by etching techniques, have been shown to be composed of sub-included PMMA domains, leading to a so-called multiple core-shell structure.

Experimental batches of linear rubber-like polyurethanes characterized by the presence of chemically different hard segments are studied and their thermal and dynamic-mechanical properties are related to the differences in chemical compositions. Interesting correlations are found between the development of crystallinity in such elastomeric poly(urethaneurea)s and the aromatic or alicyclic nature of the diisocyanate. Moreover, for a fixed ratio between hard and soft segments, and for a given composition of the soft segment, the results seem to indicate a better degree of phase separation in cycloaliphatic-based hard segment poly(urethaneurea)s than in aromatic-based hard segment poly(urethaneurea)s. Die thermischen und dynamisch-mechanischen Eigenschaften einiger linearer kautschukelastischer Polyurethane mit chemisch unterschiedlichen starren Segmenten wurden untersucht und zur chemischen Zusammensetzung in Beziehung gesetzt. Interessante Zusammenhange wurden zwischen der Kristallinitat der elastischen Polyurethanharnstoffe und der aromatischen oder cycloaliphatischen Natur der Diisocyanat-Komponenten gefunden. Daruber hinaus scheinen die Ergebnisse bei einem bestimmten Verhaltnis zwischen starren und flexiblen Segmenten und bei gegebener Zusammensetzung der flexiblen Gruppen auf eine bessere Phasenseparation bei den Polyurethanharnstoffen mit cycloaliphatischen starren Segmenten als bei solchen mit aromatischen, starren Einheiten hinzuweisen.

Influence of spinning velocities on the mechanical and structural properties of polyethylene terephthalate (PET)/nylon 6 blend fibers have been reported. Fibers of PET/nylon 6 containing a small percentage of nylon (5% by weight) have been melt-spun at 3 different spinning velocities (2,900; 3,200; 3,600 m/min). The fibers have been characterized by thermal, morphological, structrual, and mechanical analysis. Various techniques such as SEM, DSC, X-ray diffraction, hot water shrinkage (HWS), viscosity, and birefringence have been used. SEM analysis revealed that in the blend, nylon 6 is well-dispersed as spheres in the PET matrix. The blend shows a marked decrease in the melt-flow index, which in turn leads to a beneficial effect on the rheological properties of the PET without negatively influencing its mechanical characteristics. This finding results in a saving on energetical requirements of the processing, as both temperature and pressure of spinning can be decreased. © 1995 John Wiley & Sons, Inc.

The biodegradability of a multicomponent system based on biotechnological occurring polyester (poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV)) with inclusion of acrylate elastomer (polybutylacrylate) (PBA) was investigated. A bacterium which produced extracellular enzymes that degrades PHBV even when blended with PBA was isolated and tentatively designated asAureobacterium saperdae. It was observed, by morphological investigation, that, while the bacterial degradation was permitted for PBA content of 20% by weight, it was inhibited for PBA content of 30%, owing to the occurrence of a rubbery layer that prevents to the bacteria an easy accessibility in the PHBV-rich regions. In fact, owing the bacterial growth, only PHBV was metabolized, whereas no degradation of PBA was detected for blend samples. It was confirmed that the degradation proceeded via surface erosion of PHBV also in the blends. Finally, mechanical tests on PHBV/PBA specimens as a function of degradation extent have shown different behavior of the blends at different the PBA content. Thermal analysis of blends and PHBV has been reported, too

Purpose In the framework of a project aiming to improve the properties of poly(∊-caprolactone) (PCL)-based devices, we prepared novel composites and tested their in vitro biocompatibility and osteogenic capacity on human mesenchymal stromal cells (MSC) from bone marrow. Methods We prepared two functionalized derivatives, PCL-g-MAGMA and PCL-g-DMAEA, by insertion of anhydride groups by radical grafting of maleic anhydride (MA) and glycidyl-methacrylate (GMA) molecules, and by insertion of N-(dimethylamino)ethylacrylate (DMAEA) of tertiary amines groups, respectively. In addition, in order to improve the osteo-conductive properties of the materials, we also prepared the corresponding composites containing the mineral component of bone, namely hydroxyapatite (HA). Mesenchymal stromal cells (MSC) derived from bone marrow were prepared, plated onto a number of discs obtained from these functionalized derivatives and tested in terms of adhesion and vitality (by MTT test and SEM observation), and the expression of alkaline phosphatase, the early marker of osteoblastic phenotype. Results The biological in vitro assessment of the functionalized materials, PCL-g-MAGMA and PCL-g-DMAEA, appeared promising only in part, in particular the cells exhibited very poor adhesion to PCL-g-MAGMA. On the contrary, the related composites, PCL-g-MAGMA-HA and PCL-g-DMAEA-HA clearly showed that the addition of HA greatly ameliorated the cellmaterial interaction. In particular, a surprisingly increased response characterized PCL-g-MAGMA-HA, either in terms of adhesion and vitality or in terms of alkaline phosphatase activity. Conclusions Altogether these studies showed that the addition of HA nanowhiskers resulted for all basic materials, in particular PCL-g-MAGMA, in improved cell adhesion and performance.

A new series of polyimides was synthesized by addition polymerization of 4,4′-(bismaleimido)-diphenylmethane, 1,4-piperazine and an amino-terminated polydimethylsiloxane. The synthesis was carried out in m-cresol solution following a two-step procedure. Copolymers containing 15 and 20 wt.-% of the polydimethylsiloxane elastomer were prepared, together with the unmodified base copolymer. Infrared spectroscopy, 13C and 1H NMR, thermal and thermogravimetric analyses were used to characterize the copolymers. The DSC curves of all the samples showed an exotherm in the temperature range 230–280°C, attributable to curing and addition reactions involving the chain-end groups. Different glass transition temperatures (Tg) were observed, depending on the elastomer content. Thermogravimetric analysis indicated that no significant changes occur in the thermal stability of rubber-modified copolymers.

A new series of poly(ether-alkyl)oxadiazoles of general formula: with m = 3, 4, and 5 has been obtained from the corresponding polyhydrazides through thermal cyclization reaction. The polymers were characterized by infrared spectroscopy, differential scanning calorimetry, wide-angle x-ray analysis, and optical microscopy. The polymers were crystalline, with a crystalline texture and structural parameters strongly dependent on the value of m. The Tm's and Tg's value decreased with increasing number of CH2. © 1994 John Wiley & Sons, Inc.

Poly-ether-aroyl-oxadiazoles (PEODZ) of general formula: are reported. Thermal cyclization of the starting polyhydrazides, infrared, thermal, and structural characterization are discussed as function of the number of methylene spacers in the range 2–12. It is found that the position of melting is strongly dependent upon the number ofCH2, and that moldable polyoxadiazoles are obtained at × values > 7. The spherulitic nature of PEODZ is clearly revealed by thermal-optical microscopy which, together with isothermal crystallizations at the differential scanning calorimeter, gives a close insight into the crystalline organization of such polymers. © 1994 John Wiley & Sons, Inc.

It is shown that organic peroxides added during melt processing induce chemical interactions between poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV) and caprolactone to form a graft copolymer. Solvent extraction reveals also the presence of crosslinked PHBV. The copolymer is formed in small quantities, as the interaction in the melt is substantially restricted to the interfacial regions between the two immiscible polymers

Reactive polymer blending of poly(β-hydroxybutyrate) (PHB) and its valerate copolymers (PHBV) are reported, following two different methodologies, namely polymerization of rubber inclusions in the preformed matrix or reactive melt blending of preformed polymers. As second phase, poly(butyl acrylate) (PBA) and polycaprolactone (PCL) are used. The results of spectroscopic, thermal, mechanical and morphological analysis indicate the existence of chemical interactions between the blend components. Such interactions are also responsible of a drastic change in the morphology.

Rubber modified prepolymers were synthetized through a nucleophilic addition of diamines to aromatic bismaleimides, using N,N′bismaleimido-4-4′diphenylmethane (BMI), 1,4-piperazine (PyP), and an amino-terminated polydimethylsiloxane elastomer (PDMS). Thermal stability was investigated by thermogravimetric analysis (TGA) in order to elucidate the influence of diamines. Physical and rheological changes during the curing process were monitored by differential scanning calorimetry (DSC) and dynamic mechanical tests (DMA). The degree of cross-linking of the sample with PDMS was higher than that of the sample without PDMS. This effect might be due to a larger chain mobility provided by the rubber during the cure. © 1994 John Wiley & Sons, Inc.

Poly(etheraroylhydrazide) is synthesized in the presence of PA6 by means of low-temperature condensation polymerization of 4,4′-dichloroformyl-α,ω-diphenoxydodecane with terephthaloyl dihydrazide (TDH) in order to prepare polyhydrazide/poly-amide 6 (PEHZ12/PA6) blends. The thermal analysis of the blends by DSC seems to indicate that the two polymers are not interacting. Nevertheless, when the blends are subjected to an extraction process with formic acid in order to remove the PA6, the characterization of the residual PEHZ12 reveales that some interactions do occur between the constituent polymers, at least for selected compositions. Model experiments permit to hypothesize that the polymerization of PEHZ12 proceeds with a chemical interaction between amino end groups of PA6 and growing PEHZ12 chains. Polyhydrazid/Polyamid-Blends (PEHZ12/PA6) wurden durch Niedrigtemperatur-Polykondensation von 4,4′-Dichlorformyl-α,ω-diphenoxydodecan und Terephthaloyldihydrazid (TDH) zu Poly(etheraroylhydrazid) in Gegenwart von Polyamid 6 synthetisiert. Die DSC-Analysen lassen vermuten, das die zwei Polymerkomponenten nicht wechselwirken. Bei der Extraktion des PA6-Anteils der Blends mit Ameisensaure zeigt die Charakterisierung des PEHZ12-Extraktionsruckstands aber, das zumindest bei bestimmten Zusammensetzungen Wechselwirkungen zwischen den Komponenten auftreten. Modellreaktionen erlauben die Annahme, das die PEHZ12-Polymerisation zwischen den Amino-Endgruppen des PA6 und den wachsenden PEHZ12-Polymerketten ablauft.

A study on the efficiency of bio-based compounds as stabilizers for polypropylene (PP) is reported. A water extract from French maritime pine bark (Pycnogenol (R)), a by-product containing polyphenols obtained from wine production, and a carotenoid-containing oleoresin from processing of tomatoes were used. Their stabilizing activity was compared with that of a commercial phenolic antioxidant. Thermogravimetric analysis and Oxidative Induction Time measurements performed on unaged samples, as well as infrared spectroscopy on samples aged at 70 degrees C, provided evidence for the effectiveness of the natural stabilizers. Mechanical characterization was carried out on aged films and injection moulded samples. Experimental results indicated that particularly grape extract could provide long-term stabilization to PP under conditions of oxidative degradation. Therefore, it could be used as efficient and high value-added additive for polypropylene. Pycnogenol (R) also showed antioxidant activity, however the achievement of a more homogeneous dispersion in the polymer matrix could improve the mechanical performance of aged samples. (C) 2011 Elsevier Ltd. All rights reserved.

A polyphenol-containing extract from winery bio-waste (EP) has been used as an additive for a starch-based polymer (Mater-Bi). EP was used to tailor Mater-Bi properties, thus avoiding the use of synthetic polymer additives. It was found that EP was able to efficiently modulate the processing, mechanical, thermal and biodegradation properties. The observed decrease in melt viscosity showed that EP could improve productivity in polymer processing. Owing to the plasticizing activity of the additive, larger values of elongation at break were found. Moreover, the Mater-Bi crosslinking, which occurs upon thermal aging, was delayed in the presence of EP. Finally, the bio-disintegration rate of doped Mater-Bi decreased, thus suggesting that EP acted as an antimicrobial agent by interfering with the bio-digestion of the polymer films.

The effect of crystal polymorphism on barrier and mechanical properties of PLLA is detailed in this contribution. PLLA films containing different amounts of alfa and alfa' crystal forms were prepared by annealing quenched PLLA at different temperatures. The polymorphic structure of the films was analyzed by X-ray diffraction. Mechanical properties and permeability to water vapor were investigated as a function of degree of crystallinity (wC) and related to crystal polymorphism developed during annealing. The polymorphic structure of PLLA significantly affects mechanical and barrier properties. The alfa crystal modification provides a better barrier to water vapor and a higher Young’s modulus, compared to films containing the alfa' modification, but a lower elongation at break. The varied barrier and mechanical properties were correlated to the different packing of PLLA chains in the two analyzed polymorphs. The conformational disorder of the alfa' form makes this structure a mesophase (condis crystal), with remarkable effects on material properties.

The temperature dependent optical properties of a poly(methyl methacrylate) (PMMA) ethylene-co-vinylacetate (EVA) blend (PMMA-EVA) were investigated in order to study its thermo-optical behaviour in the temperature range 30-70-degrees-C. The thermal coefficients of the refractive index dn/dt of PMMA-EVA, PMMA and EVA were measured as a function of the temperature. The observed trend of the thermal coefficients is related to a first-order phase transition of the EVA component. A comparison with the results of calorimetric investigations by differential scanning calorimetry (DSC) is also reported. The possible use of this material in optics is described.