Effect of blending lignin biopolymer on the biodegradability of polyolefin plastics

The ability of the lignin-degrading microorganism Phanerochaete chrysosporium to attack polyethylene and polypropylene was investigated using a series of polymer blends containing 10, 20 and 30% lignin obtained from the waste product of pulp and paper industry. In the cultivation medium, lignin peroxidase and Mn(II)peroxidase activities were detected. Degradation was verified by quantitative u.v. spectrophotometric analysis of the cultivation medium and by liberation of CO₂ from the blends. Measurement of the tensile strength after 30-days cultivation showed that the mechanical properties of the polymer blends were decreased during the biodegradation process. The isolation of oligomer fractions by tetrahydrofuran (THF) extraction of biodegraded polymers and their characterization by gel permeation chromatography (GPC), u.v. and Fourier transmission infrared (FTIR) spectroscopy indicates that biotransformation of the lignin component during the cultivation process initiates partial biodegradation of the synthetic polymer matrix.     

Molecular dynamics and dissipative particle dynamics simulations for prediction of miscibility in polyethylene terephthalate/polylactide blends

The miscibility of polyethylene terephthalate (PET)/polylactide (PLA) blends is studied through atomistic molecular dynamics (MD) and mesoscale dissipative particle dynamics (DPD) simulation. Five PET/PLA blends (with the weight ratio at 90/10, 70/30, 50/50, 30/70 and 10/90) as well as pure PET and PLA are examined. The solubility parameter values obtained by using the MD simulation are in good agreement with the reference data. The Flory–Huggins parameters, χ, which are computed for different blends and determined from the cohesive energy densities, with the radial distribution functions g(r) of the inter-molecular atoms, suggest that PET is completely miscible with PLA over the entire composition range. This is further proved by the mesoscopic morphologies of PET/PLA blends. All the simulation results are qualitatively consistent with the experimental results, and demonstrate that the modelling strategies in this study may serve as a powerful tool for predicting miscibility and mesoscopic morphology of polymer blends.     

Preparation of poly(l-lactide) blends and biodegradation by Lentzea waywayandensis

As a biodegradable polyester, polylactide (PLA) has applications as a packaging material, in biomedical fields and tissue engineering. With the dual aim of improving its properties and biodegradability, PLA was blended with other polymers such as gum arabic, thermoplastic starch, microcrystalline cellulose, polyethylene glycol and polyhydroxy butyrate in 1:1 (w/w) by melt-blending technique. The thermal properties of the blends were compared with that of unblended PLA by thermo-gravimetric analysis. Biodegradation using Lentzea waywayandensis was in the order of PLA–gum arabic?>?PLA–thermoplastic starch?>?PLA(virgin)?>?PLA–microcrystalline cellulose?>?PLA–polyethylene glycol?>?PLA–polyhydroxy butyrate. Weight loss of 99?% (w/w) was noted within 4?days for PLA–thermoplastic starch and PLA-gum arabic blends.     

Factors Governing Intercalation of Fullerenes and Other Small Molecules Between the Side Chains of Semiconducting Polymers Used in Solar Cells

While recent reports have established significant miscibility in polymer:fullerene blends used in organic solar cells, little is actually known about why polymers and fullerenes mix and how their mixing can be controlled. Here, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and molecular simulations are used to study mixing in a variety of polymer:molecule blends by systematically varying the polymer and small‐molecule properties. It is found that a variety of polymer:fullerene blends mix by forming bimolecular crystals provided there is sufficient space between the polymer side chains to accommodate a fullerene. Polymer:tetrafluoro‐tetracyanoquinodimethane (F4‐TCNQ) bimolecular crystals were also observed, although bimolecular crystals did not form in the other studied polymer:non‐fullerene blends, including those with both conjugated and non‐conjugated small molecules. DSC and molecular simulations demonstrate that strong polymer–fullerene interactions can exist, and the calculations point to van der Waals interactions as a significant driving force for molecular mixing.     

FT-IR imaging spectroscopy of phase separation in blends of poly(3-hydroxybutyrate) with poly(L-lactic acid) and poly(epsilon-caprolactone)

The detection of phase separation and identification of miscibility in biopolymer blends is an important aspect for the improvement of their physical properties. In this article, the phase separation in blends of poly(3-hydroxybutyrate) (PHB) with poly(L-lactic acid) (PLA) and poly(epsilon-caprolactone) (PCL), respectively, has been studied as a function of the blend composition by FT-IR imaging spectroscopy. For both polymer blend systems, a miscibility gap has been found around the 50:50% (w/w) composition of the two components. Furthermore, the separating phases have been identified as blends of the two polymer components and their compositions could be determined from calibrations based on the spectra of the blends in the compositional range of miscibility. The data derived from FT-IR spectroscopic imaging were corroborated by additional DSC analyses and mechanical stress-strain measurements of polymer blend films, which exhibited a characteristic fracture behavior as a function of PHB composition.     

Preparation and properties of banana fiber-reinforced composites based on high density polyethylene (HDPE)/Nylon-6 blends

Banana fiber (BaF)-filled composites based on high density polyethylene (HDPE)/Nylon-6 blends were prepared via a two-step extrusion method. Maleic anhydride grafted styrene/ethylene–butylene/styrene triblock polymer (SEBS-g-MA) and maleic anhydride grafted polyethylene (PE-g-MA) were used to enhance impact performance and interfacial bonding between BaF and the resins. Mechanical, crystallization/melting, thermal stability, water absorption, and morphological properties of the composites were investigated. In the presence of SEBS-g-MA, better strengths and moduli were found for HDPE/Nylon-6 based composites compared with corresponding HDPE based composites. At a fixed weight ratio of PE-g-MA to BaF, an increase of BaF loading up to 48.2 wt.% led to a continuous improvement in moduli and flexural strength of final composites, while impact toughness was lowered gradually. Predicted tensile modulus by the Hones–Paul model for three-dimensional random fiber orientation agreed well with experimental data at the BaF loading of 29.3 wt.%. However, the randomly-oriented fiber models underestimated experimental data at higher fiber levels. It was found that the presence of SEBS-g-MA had a positive influence on reinforcing effect of the Nylon-6 component in the composites. Thermal analysis results showed that fractionated crystallization of the Nylon-6 component in the composites was induced by the addition of both SEBS-g-MA and PE-g-MA. Thermal stability of both composite systems differed slightly, except an additional decomposition peak related to the minor Nylon-6 for the composites from the HDPE/Nylon-6 blends. In the presence of SEBS-g-MA, the addition of Nylon-6 and increased BaF loading level led to an increase in the water absorption value of the composites.     

Biodegradation of poly(epsilon-caprolactone)/starch blends and composites in composting and culture environments: the effect of compatibilization on the inherent biodegradability of the host polymer

The biodegradability of poly(epsilon-caprolactone) (PCL) was studied in blends and composites of modified and granular starch. Four types of PCL-starch compositions were prepared: (i) PCL-granular starch blends; (ii) hydrophobic coating of starch particles by n-butylisocyanate (C(4) starch) and octadecyltrichlorosilane (C(18) starch), followed by melt blending with PCL; (iii) PCL-starch blends compatibilized by PCL-g-dextran grafted copolymer (PGD); and (iv) PCL-grafted starch particles (PGS) as obtained by in situ ring-opening polymerization of caprolactone (CL) initiated directly from hydroxyl functions at the granular starch surface. Biodegradability of these materials was measured by monitoring the percentage of weight loss in composting and the rate of fungal colonization when samples were used as a sole carbon source for fungus (A. niger). Intrinsic viscosity [eta] of host PCL chains was measured after extraction of composted samples in boiled chloroform. SEM was used to study the surface morphology after compost incubation of the samples. The inherent biodegradability of host polymer was enhanced with surface compatibilization during composting for longer incubation. It was observed that the weight loss during composting increased with the decrease in interfacial tension between filler and polymer. In general, it was concluded that inherent biodegradability does not depend very significantly on the concentration of starch in the polyester matrix, but on the compatibilization efficiency. The effect of the PCL fraction in the graft copolymer, when used as compatibilizer, was also studied on the biodegradability of the host polymer.     

Polysaccharide-based polymer blends: Methods of their production

The existing methods of preparing polymer blends of cellulose, chitin and chitosan with natural and synthetic polymers and their applications are reviewed. The methods of solid-phase blending of these polymers under conditions of joint action of high pressure and shear deformation are discussed. Normally, under these conditions the processes of dispersion of polymer particles, amorphization, mixing at different levels, depolymerization as well as a chemical interaction resulting in formation of branched and crosslinked structures can take place. The probability and intensity of these processes depend in many respects on the type and magnitude of the external force, but the properties of the polymers are of higher importance. The advantages of the method of joint action of high pressure and shear deformation compared to the conventional techniques of polysaccharides mixtures production are shown.     

The effect of macromolecular crowding on protein aggregation and amyloid fibril formation

Macromolecular crowding is expected to have several significant effects on protein aggregation; the major effects will be those due to excluded volume and increased viscosity. In this report we summarize data demonstrating that macromolecular crowding may lead to a dramatic acceleration in the rate of protein aggregation and formation of amyloid fibrils, using the protein alpha-synuclein. The aggregation of alpha-synuclein has been implicated as a critical factor in development of Parkinson's disease. Various types of polymers, from neutral polyethylene glycols and polysaccharides (Ficolls, dextrans) to inert proteins, are shown to accelerate alpha-synuclein fibrillation. The stimulation of fibrillation increases with increasing length of polymer, as well as increasing polymer concentration. At lower polymer concentrations (typically up to approximately 100 mg/ml) the major effect is ascribed to excluded volume, whereas at higher polymer concentrations evidence of opposing viscosity effects become apparent. Pesticides and metals, which are linked to increased risk of Parkinson's disease by epidemiological studies, are shown to accelerate alpha-synuclein fibrillation under conditions of molecular crowding.     

Miscibility studies of HPMC/PEG blends in water by viscosity,density, refractive index and ultrasonic velocity method

Hydroxy propyl methyl cellulose (HPMC)/polyethylene glycol (PEG) blends are edible polymer films used for food packing and directly in foodstuffs. However, they are water-soluble in ordinary temperature and have good mechanical properties. The miscibility of HPMC/PEG blend in water was studied by viscosity, ultrasonic velocity, density and refractive index techniques at 30 and 50 °C. Using viscosity data, the interaction parameters μ and α were calculated. These values revealed that HPMC/PEG blend is miscible when the HPMC content is more than 60 wt.% in the blend at 30 and 50 °C, below which is immiscible. Further the result was also confirmed by ultrasonic velocity, density, refractive index measurements, which also revealed that the change in temperature has no significant effect on the miscibility of HPMC/PEG polymer blend.     

Interfacial molecular recognition between polysaccharides and calcium carbonate during crystallization

Based on the basic principles of biomineralization, using beta-cyclodextrin, hepatin and soluble starch as organic matrices, employing the biomimetic method, the crystallization of CaCO(3) was studied by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction analysis (XRD), scanning electronic microscopy (SEM), thermal gravity-differential thermal analysis and conductivity analysis. The results show that polysaccharides have an effect on the crystallization of CaCO(3). CaCO(3) crystals also have an effect on polysaccharides. The possible mechanism of this interaction is discussed.     

Preparation and characterization on mechanical and antibacterial properties of chitsoan/cellulose blends

Polysaccharides-based membranes of chitosan and cellulose blends were prepared using trifluoroacetic acid as a co-solvent. Morphology and mechanical property of prepared membranes were studied by Instron and dynamic mechanical thermal analysis. The mechanical and dynamic mechanical thermal properties of the cellulose/chitosan blends appear to be dominated by cellulose, suggests that cellulose/chitosan blends were not well miscible. It is believed that the intermolecular hydrogen bonding of cellulose is supposed to be break down to form cellulose–chitosan hydrogen bonding; however, the intra-molecular and intra-strand hydrogen bonds hold the network flat. The reduced water vapor transpiration rate through the chitosan/cellulose membranes indicates that the membranes used as a wound dressing may prevent wound from excessive dehydration. The chitosan/cellulose blend membranes demonstrate effective antimicrobial capability against Escherichia coli and Staphylococcus aureus, as examined by the antimicrobial test. These results indicate that the chitosan/cellulose blend membranes may be suitable to be used as a wound dressing with antibacterial properties.     

Release Mechanisms Behind Polysaccharides-Based Famotidine Controlled Release Matrix Tablets

Polysaccharides, which have been explored to possess gelling properties and a wide margin of safety, were used to formulate single-unit floating matrix tablets by a direct compression technique. This work has the aim to allow continuous slow release of famotidine above its site of absorption. The floating approach was achieved by the use of the low density polypropylene foam powder. Polysaccharides (κ-carrageenan, gellan gum, xyloglucan, and pectin) and blends of polysaccharides (κ-carrageenan and gellan gum) and cellulose ethers (hydroxypropylmethyl cellulose, hydroxypropylcellulose, sodium carboxymethyl cellulose) were tried to modulate the release characteristics. The prepared floating tablets were evaluated for their floating behavior, matrix integrity, swelling studies, in vitro drug release studies, and kinetic analysis of the release data. The differential scanning calorimetry and Fourier transform infrared spectroscopy studies revealed that changing the polymer matrix system by formulation of polymers blends resulted in formation of molecular interactions which may have implications on drug release characteristics. This was obvious from the retardation in drug release and change in its mechanistics.     

Properties of extracellular polymer having an effect on expression of activated sludge

Extracellular polymer in activated sludge was found to affect expression of these sludge by raising the value of the average specific resistance (α_av) during filtration and lowering the value of the modified consolidation coefficient (C_e) during consolidation. Further, the addition of extracellular polymer to the sludges caused higher values of α_av and lower values of C_e. The logarithmic plots of α_av and C_e against the quantity of extracellular polymer was linear. When these two values (α_av and C_e) of each activated sludge were plotted against the quantity of extracellular polymer extracted from each sludge, they were correlated by a single straight line with two exceptions. These were the return sludge of a textile factory and the anaerobically digested sludge of a sewage treatment plant. These exceptions indicate that the values of α_av of these sludges are higher than those of other sludges containing the same amount of extracellular polymer and that of C_e are lower than those of other sludges. It was confirmed that the extracellular polymer of these two sludges contains a lot of polysaccharides of the molecular weight 600–100,000 (with a standard of polyethylene glycol) by gel chromatography. The effects of the flocculant on dewatering were investigated. The effects of the cationic polymer flocculant addition to the extracellular polymer were analyzed using an ultrafiltration cell (molecular weight cut-off 10,000). The ultrafiltration rate of extracellular polymer was much improved by adding a cationic polymer flocculant. The removal of extracellular polymer by adding cationic polymer flocculant was ascertained by measuring the molecular weight distribution of the polysaccharides. On the other hand, no flocculations of extracellular polymer and sludge by adding anionic and nonionic polymer flocculant could be observed.     

Influence of Donor Polymer on the Molecular Ordering of Small Molecular Acceptors in Nonfullerene Polymer Solar Cells

Nonfullerene polymer solar cells (PSCs) based on polymer donors and nonfullerene small molecular acceptors (SMAs) have recently attracted considerable attention. Although much of the progress is driven by the development of novel SMAs, the donor polymer also plays an important role in achieving efficient nonfullerene PSCs. However, it is far from clear how the polymer donor choice influences the morphology and performance of the SMAs and the nonfullerene blends. In addition, it is challenging to carry out quantitative analysis of the morphology of polymer:SMA blends, due to the low material contrast and overlapping scattering features of the π–π stacking between the two organic components. Here, a series of nonfullerene blends is studied based on ITIC‐Th blended with five different donor polymers. Through quantitative morphology analysis, the (010) coherence length of the SMA is characterized and a positive correlation between the coherence length of the SMA and the device fill factor (FF) is established. The study reveals that the donor polymer can significantly change the molecular ordering of the SMA and thus improve the electron mobility and domain purity of the blend, which has an overall positive effect that leads to the enhanced device FF for nonfullerene PSCs.     

Carboxylate-induced degradation of poly(3-hydroxybutyrate)s

This communication shows that thermal degradation of poly(3-hydroxybutyrate)s (PHBs) is induced by carboxylate groups via a newly proposed E1cB mechanism. In PHBs with end groups in the form of carboxylic acid salts with Na+, K+, and Bu4N+ counterions, the proposed mechanism explains the dependence of thermal stability on the size of the counterion. The degradation via intermolecular alpha-deprotonation by carboxylate is suggested to be the main PHB decomposition pathway at moderate temperatures. The results of the present study show the ability to control the degradation and stability of poly(3-hydroxybutyrate)s as well as of their blends via chemical structure and concentration of the carboxylate polymer end groups.     

Thermogravimetric investigation on co-combustion characteristics of tobacco residue and high-ash anthracite coal

The thermal behavior of high-ash anthracite coal, tobacco residue and their blends during combustion processes was investigated by means of thermogravimetric analysis (20 K min(-1), ranging from ambient temperature to 1273 K). Effects of the mixed proportion between coal and tobacco residue on the combustion process, ignition and burnout characteristics were also studied. The results indicated that the combustion of tobacco residue was controlled by the emission of volatile matter; the regions were more complex for tobacco residue (four peaks) than for coal (two peaks). Also, the blends had integrative thermal profiles that reflected both tobacco residue and coal. The incorporation of tobacco residue could improve the combustion characteristics of high-ash anthracite coal, especially the ignition and burnout characteristics comparing with the separate burning of tobacco residue and coal. It was feasible to use the co-combustion of tobacco residue and high-ash anthracite coal as fuel.     

Aqueous solutions of native and hydrophobically modified polysaccharides: temperature effect

Amphiphilic polysaccharides, obtained by the attachment of various hydrocarbon groups onto dextran, are studied in aqueous solutions. The viscosity of their aqueous solutions is examined as a function of concentration and temperature in the range 25-65 degrees C. Varying polymer concentration, viscosity follows a polynomial development of Huggins equation in which the coefficients can be calculated from the Huggins constant determined in the dilute domain (Matsuoka-Cowman equation). For all polymers, the solution viscosity follows an Arrhenius-like variation with temperature. The activation energy of the aqueous solutions is determined as a function of polymer concentration and structural characteristics (nature and amount of grafted hydrocarbon groups). The variation of activation energy with polymer concentration is shown to be consistent with predictions based on the Matsuoka-Cowman equation combined with the equation of Andrade. This conclusion is extended to other polysaccharides using data from the literature.     

Blends of reverse enteric polymer with Enteric and pH-independent polymers: mechanistic investigations for tailoring drug release

Blends of conventional reverse enteric polymer with enteric polymers result in insoluble polyelectrolyte complexes and hence cannot be used in film coatings. We report a new set of miscible blends of a new reverse enteric polymer (NREP) synthesized by us with enteric and pH-independent polymers. The nature of interactions between polymers in the blends has been established by analyzing Fourier transform infrared (FTIR) spectra. The extent of interaction has been investigated by thermal analysis and quantified in terms of parameters K1 and K2 in the Schneider equation. Based on these values, the interactions between NREP and these polymers have been ranked in the order EC (ethylcellulose) < ES (Eudragit S) < HPMCP (hydroxypropyl methylcellulose phthalate). The quantification of interactions in blends helps explain the release pattern of cefuroxime axetil (CA) at gastric pH and tailor the release of other drugs according to their pharmacokinetic characteristics. The understanding also provides a more rational approach for selection of polymers and their content in the coating compositions, rather than an empirical approach.     

Thermally Stable All‐Polymer Solar Cells with High Tolerance on Blend Ratios

Tuning the blend composition is an essential step to optimize the power conversion efficiency (PCE) of organic bulk heterojunction (BHJ) solar cells. PCEs from devices of unoptimized donor:acceptor (D:A) weight ratio are generally significantly lower than optimized devices. Here, two high‐performance organic nonfullerene BHJ blends PBDB‐T:ITIC and PBDB‐T:N2200 are adopted to investigate the effect of blend ratio on device performance. It is found that the PCEs of polymer‐polymer (PBDB‐T:N2200) blend are more tolerant to composition changes, relative to polymer‐molecule (PBDB‐T:ITIC) devices. In both systems, short‐circuit current density (J_sc) is tracked closely with PCE, indicating that exciton dissociation and transport strongly influence PCEs. With dilute acceptor concentrations, polymer‐polymer blends maintain high electron mobility relative to the polymer‐molecule blends, which explains the dramatic difference in PCEs between them as a function of D:A blend ratio. In addition, polymer‐polymer solar cells, especially at high D:A blend ratio, are stable (less than 5% relative loss) over 70 d under continuous heating at 80 °C in a glovebox without encapsulation. This work demonstrates that all‐polymer solar cells show advantage in operational lifetime under thermal stress and blend‐ratio resilience, which indicates their high potential for designing of stable and scalable solar cells.