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Structural, mechanical, thermal and surface properties comprising biodegradable aromatic–aliphatic polymer poly(butylene adipate-co-terephthalate) (PBAT) and the wheat stalk-based nanocellulose (NCC) were studied. The materials were found to comprise the compatible and yet phase-segregated constituents which kept their identity in the nanocomposite materials. The NCC phase was found to be homogeneously dispersed in the PBAT matrix inside. Similar to the corresponding microcomposites, the investigated nanocomposites were found to be stable within their desired application temperature as packaging materials. The tensile properties of the nanocomposites degraded in terms of strain at break, tensile strength and tensile modulus. At higher filler content, the reinforcing effect dominated leading to an increase in indentation modulus and hardness, and a decrease in the work of elastic deformation. The wettability and the water absorption capacity of the materials increased with NCC content thereby enhancing the biodegradability of the composites.

International audience; We follow the assumption that the dilatational response of glassy polymers can be characterized by a back-stress type analog that includes a thermal expansion for each elastic component and with a viscosity that is dependent on the expansion of the elastic back-stress component. To this, we add the assumption of an unloaded equilibrium temperature that correlates to the past processing through the viscous flow. After setting this in a thermodynamically consistent structure, elastic, elastic back-stress, thermal expansion, back-stress thermal expansion, heat capacity, and viscous damping are evaluated using existing experiments for the response of polycarbonate over the glassy and rubbery ranges. For the demonstration, this is done entirely using a WLF shift factor that is augmented to include, in addition, back strain superposition. We then examine the resulting model under different thermal and mechanical loadings that have the material passing through the glass transition.

Lipids in the Ready-to-use Therapeutic Food (RUTF) comprise various types of triglycerides such as palmitic, oleic and linoleic acids. Dynamic studies of the dielectric properties such as impedance, permittivity and loss tangent of the triglycerides at different temperatures ranging from 25 to −30 °C and frequencies from 10−2 Hz to 5 × 106 Hz were performed by electrochemical impedance spectroscopy (EIS). The outcomes of EIS were associated together with the analysis of Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) in order to analyse the dielectric signals obtained. As expected, FTIR results suggest the presence of saturated and unsaturated triglycerides of the palmitic, oleic and linoleic acids. Besides, there are absorbance bands of functional groups that reflect the presence of proteins. The dielectric relaxation and dielectric constant were evaluated from the impedance and permittivity spectra, respectively. The results imply the RUTF possesses long-range motion of dipoles against lower temperatures. The phase transitions observed in RUTF as indicated by the DSC cooling curve (crystallization), lead to the shifting of dielectric properties in impedance and permittivity.

Dynamic studies of several processed cheeses were carried out for evaluation of their dielectric properties and their relaxation behavior. Impedance spectroscopy has been used to study the systems under discussion in low-frequency domain. A substantial number of impedance spectra will be given and discussed that relate the dielectric properties to food nutrients. Also influence of moisture on food quality might be evaluated.

We present an overview for the basic fundamental of thermal analysis, which is applicable for educational purposes, especially for lecturers at the universities, who may refer to the articles as the references to “teach” or to “lecture” to final year project students or young researchers who are working on their postgraduate projects. Description of basic instrumentation [i.e. differential scanning calorimetry (DSC) and thermogravimetry (TGA)] covers from what we should know about the instrument, calibration, baseline and samples’ signal. We also provide the step-by-step guides for the estimation of the glass transition temperature after DSC as well as examples and exercises are included, which are applicable for teaching activities. Glass transition temperature is an important property for commercial application of a polymeric material, e.g. packaging, automotive, etc. TGA is also highlighted where the analysis gives important thermal degradation information of a material to avoid sample decomposition during the DSC measurement. The step-by-step guides of the estimation of the activation energy after TGA based on Hoffman’s Arrhenius-like relationship are also provided.

Background Ghŗta mūrcchana is a process of pre-treatment recommended in Ayurveda to purify ghee before it can be used for siddha ghŗta which is claimed to improve the properties of the ghee in general and that of the prepared siddha ghŗta. Objective This work is aimed at studying the physiochemical properties of ghee and mūrcchita ghŗta in order to understand the impact of ghŗta mūrcchana process. Materials and methods Ghee and mūrcchita ghŗta were prepared from the milk of local Pahadi, Jersey and Holstein cows. The samples were characterized by FTIR spectroscopy, differential scanning calorimetry and free fatty acid measurements. Results Among the samples studied, the Holstein cow ghee was found to contain the least amount of free acid (1.34%) whereas ghŗta mūrcchana process led to further decrease in the free acid content polymorphism was observed in the samples as evidenced by multiple melting points. In most cases, mūrcchita ghŗta was found to contain less solid fat than the corresponding ghee implying that the high melting compound was converted to low melting one during the process. Conclusion The observed lowering of free fatty acid and solid fat contents in the ghee samples may provide a possible validation to the performance enhancement of the ghŗta mūrcchana process.

The focus is on a peanut suspension in which starch is added and that exhibits specific mechanical characteristics relevant for food products. The mixture is composed of water, lipids, starch, and proteins. The process consists of blending together the different constituents, and the study changes the experimental conditions to tune the mechanical behavior of the mixture. The rheological properties (viscosity, indentation) and physical parameters such as color, dry extract, and particle size distribution were measured. The matrix behavior was studied after a centrifugation step necessary to determine stability of the emulsion, and for varying shearing durations. Short shearing duration induce a maximum of firmness, observed by measuring indentation resistance, and a maximum of spreadability, evaluated by shear rheometry. On the contrary, long shearing durations destabilize the matrix emulsion by increasing the oil separation capacity. This study observes structural changes in the rheological behavior of this analogue artificial cheese that correlates with the extent of shearing.

Star-shaped polystyrene-block-polybutadiene-block-polystyrene (SBS) block copolymer (BCP) was subjected to epoxidation reaction using m-chloroperoxy benzoic acid (MCPBA). The epoxidized SBS block copolymer (eSBS) was then blended with diglycidyl ether of bisphenol-A based epoxy resin (EP) and cross-linked with methylene dianiline (MDA). The materials were characterized by different techniques such as Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The FTIR spectrumwith the peak located at 890 cm−1 and 1230 cm−1 attested the occurrence of epoxidation reaction. The nanophase separated structures as demonstrated by transmission electron microscopy were induced in the eSBS/EP blends by epoxidized eSBS.

International audience; Peanut proteins are mostly composed of arachins and conarachins, globular proteins that can form gels under thermal denaturation or enzymatic treatment. We explored here how ionic strength (0.5 M or 0.8 M) and gelation process (a thermal treatment preceded or not by an enzymatic pre-treatment) could affect peanut protein gel properties. Gel formation and final properties were characterized by rheology, and gel structure was observed by confocal microscopy. We found that the ionic strength imposed during protein extraction determines the arachins/conarachins ratio, and that conarachins-rich samples give stronger gels, which is attributed to their higher content in free thiol groups and lysine residues. The gel storage modulus exhibited a power-law dependence with the protein concentration, which exponent depended on the gelation process. Rheological results, together with confocal microscopy imaging, showed that an enzymatic pre-treatment resulted in denser structures than when a simple thermal treatment was applied.

Structural, thermal and mechanical properties of the compostable composites comprising a biodegradable aliphatic-aromatic copolyester (namely, the poly(butylene adipate-co-terephthalate; PBAT), and microcrystalline cellulose (MCC) derived from agricultural waste, the wheat stalk, were investigated. Purely physical interaction between the components was found to be responsible to get the MCC phase quite uniformly embedded in the PBAT matrix, the latter being the dominating component of the composites surface. There were two distinct thermally activated degradation regimes characterized by separate activation processes corresponding to the decomposition of the MCC and the PBAT phases, respectively. The physically bound and rather weak but large PBAT-MCC interfacial areas provoked more rapid thermal degradation of the composites compared to the pure components. While the PBAT acted as a highly ductile material upon tensile loading, the composites maintained high ductility only up to 20% by weight of the MCC. The drastic reduction in the ductility for higher filler loading was attributed to the possible void formation at the interfacial region followed by crack initiation and propagation leading eventually to the premature specimen fracture. The composite materials thus fabricated were hence found to suit for low-load bearing applications.

We investigate the ways of improving thermal and mechanical properties of diglycidyl ether of bisphenol-A (DGEBA) based thermoset resin using diaminodiphenylsulphone (DDS) as hardener and using epoxidized polystyrene/polybutadiene-based triblock copolymers as modifier. The epoxidation was performed. The targeted chemical modification using meta-chloroperoxybenzoic acid (m-CPBA) of the copolymer was performed whereby the epoxidation of the butadiene chains mainly took place at 1,4 linkages. The modification copolymer was found to contribute in enhancing the mechanical performance of the blends with epoxy resin. The results indicated the formation of nanostructured morphology in the blends attributable to their enhanced impact strength.BIBECHANA 16 (2019) 196-203

Micro- and nanocrystalline cellulose were extracted from wheat stalk (WS) using different thermomechanical and chemical treatments and characterized by spectroscopic, microscopic and diffraction techniques. The virgin WS fibers were found to be structurally quite similar to the commercial microcrystalline cellulose (MCC). Similar to the commercial one, the MCC extracted from the WS possessed intense infrared (IR) peaks whereas those peaks became more broader in the nanocrystalline cellulose (NCC) of the same origin, which can be attributed to possible breakdown of inter- and intramolecular H-bonding due to strong acid treatment of the MCC. Microscopic results revealed characteristic textures of the MCC and the NCC, the MCC being irregular bundles of the primary crystals bound together with the amorphous phase. The latter was found to disintegrate upon acid hydrolysis giving rise to the rod-shaped nanocrystals having much larger surface area and thus possessing more intense hydrophilic character. The MCC was found to be more stable than the NCC which can be attributed to the presence of protective and binding coating provided by the amorphous cellulosic matter.BIBECHANA 16 (2019) 177-186

Functional grading is used to push the load capacity of parts to within the upper bound of what is theoretically possible. Using interpenetrating polymer networks (IPNs), a material system used to achieve grading during printing, the possibility of producing realistic grading of acrylate/epoxy IPNs is studied with the goal of increasing load capacity to within the limit of what is possible, and substantially beyond the load capacity possible with any uniform mixture of this IPN system. In the process, an upper bound of possible improvement is established for a plate with a circular hole in tensions, and the grading for this plate is adjusted to give an optimal load capacity near this upper bound. The optimal grading proposed is different from that shown in previous work due to the simultaneous consideration of both the effect of grading on elastic moduli and on the ultimate stress. A similar study was done for an L-shaped bracket indicating similar improvements over uniform brackets. Keywords: Functionally graded material, Interpenetrating polymer networks, Load capacity, Finite element method, Optimization

This contribution addresses the relationships between the structure and gas transport properties of nanoporous thermostable cyanate ester resins (CERs) derived from polycyclotrimerization of 1,1′-bis(4-cyanatophenyl)ethane in the presence of 30 or 50 wt% of inert high-boiling temperature porogens (i.e., dimethyl- or dibutyl phthalates), followed by their quantitative removal. The nanopores in the films obtained were generated via a chemically induced phase separation route with further porogen extraction from the densely crosslinked CERs. To ensure a total desorption of the porogen moieties from the networks, an additional short-term thermal annealing at 250 °C was performed. The structure and morphology of such nanoporous CER-based films were investigated by FTIR and SEM techniques, respectively. Further, the gas transport properties of CER films were analyzed after the different processing steps, and relationships between the material structure and the main gas transport parameters were established.

International audience

Summary This work describes properties of a new polymeric system obtained after melt reaction between poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] with 40% (in mass) of epoxidized natural rubber (ENR). Differential scanning calorimetry (DSC), thermogravimetry, infra-red spectroscopy and confocal optical microscopy analysis were performed on this system. Before melt reaction, we found that ENR particles with diameters of more than 2 µm were homogeneously distributed in P(3HB-co-3HHx) phase using confocal optical microscope. From infrared spectroscopy, reaction engaged during the thermal cycle for sample preparation, leads to a melt reaction associated with inhibition of crystallization of P(3HB-co-3HHx) in the blend. This is also observed in DSC analysis. Furthermore, a progressive mass loss of up to 10% was observed after five half-time of melt reaction by utilizing isothermal procedure in thermogravimetry.

Interpenetrated Polymer Networks (IPNs) were produced from the simultaneous UV-photocuring of Bisphenol A propoxylate diacrylate (BPA-PDA) and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (ECH) under a polychromatic source. Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) were used to investigate the morphology of the samples, when dependence in thermal stability with the composition was evidenced from Thermogravimetric Analysis (TGA). The aptitude to create a wide range of thermomechanical properties was investigated towards Differential Scanning Calorimetry (DSC), Dynamic mechanical Analysis (DMA) and tensile tests. Post-curing contributes to increase the glass transition and the strain at break of the materials, and is also responsible to higher resistance to thermal degradation. Results show promising possibilities for the future development of graded materials with property control at different scales.

Thermostable nanocomposites based on densely cross-linked Cyanate Ester Resins (CER), derived from bisphenol E and doped by 0.01–10 wt.% epoxycyclohexyl-functionalized polyhedral oligomeric silsesquioxane (ECH-POSS), were synthesized and characterized in detail by means of TEM, SAXS, EDXS, FTIR, DSC, DMA, TGA, far-IR and creep rate spectroscopy techniques. It was revealed that ultra-low POSS contents (≪1 wt.%), covalently embedded into CER network, substantially changed its nanostructure and properties. This resulted in changing network dynamics; increasing glass transition temperatures by 20–50 °C; enhancing high temperature elastic and creep resistance properties, and increasing thermal stability under inert atmosphere at T

Understanding the evolution of the cooperative molecular mobility as a function of time and temperature remains an unsolved question in condensed matter physics. Many recent works concern the question of the molecular dynamic slowdown in a temperature domain ranging from the crossover temperature T c (beginning of cooperative relaxation) down to the calorimetric glass transition temperature T g. Recent studies have shown that the estimation of cooperativity length based on calorimetric investigations using Donth’s approach can be extended to a wider temperature range from T g to T c. To describe the relaxation time evolution and the characteristic length evolution of cooperative motions, besides the Donth’s fluctuation approach other models exist in the literature such as “4 points correlation function” model. Whatever the model used, calorimetric investigations are needed to estimate the heat capacity as a function of the temperature. In this work, we have focused our attention on the modulated temperature differential scanning calorimetry (MT-DSC) experiments and we have tested different MT-DSC protocols allowing the heat capacity determination. For this goal we decided to work on different amorphous glass formers in order to cover a large range of glass transition temperature. The influence of the protocol used on the cooperativity length calculation is discussed in detail. Lissajous figures were constructed to verify whether the steady state is reached.

In this work, we investigate the morphological and mechanical properties of blends of diglycidyl ether of bisphenol-A (DGEBA) and epoxidized polystyrene–polybutadiene star block copolymer (epST3) using diamino-diphenyl sulphone (DDS) as a hardener. The epoxidation of the star block copolymer was performed using meta-chloroperoxybenzoic acid (m-CPBA). Chemical modification of the copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy while the morphology of the blends was analyzed by microscopic techniques. The mechanical behavior of the blends was analyzed by recording microindentation as well as impact tests. It has been demonstrated that the completely macrophase-separated morphology of the blends could be dispersed into the structures comprising co-continuous networks of the block copolymer phase and the epoxy resin leading to an increment in impact strength. At the same time, the hardness and stiffness of the blends, as shown by the indentation microhardness and indentation modulus, was maintained to a pretty high level.

Summary A star shaped polystyrene-block-polybutadiene-block-polystyrene (SBS) block copolymer was subjected to epoxidation reaction using different reagents such as m-chloroperoxy benzoic acid (MCPBA), peracetic acid (PAA), performic acid (PFA) and hexaflouro-isopropanol (HFIP). All the methods led to the targeted modification of the block copolymer satisfactorily, some of them also accompanying rapid side reactions. The epoxidized polymer was then blended with epoxy resin comprising diglycidyl ether of bisphenol-A in presence of methylene dianiline (MDA) as hardener. The mixing of the epoxidized block copolymer into the epoxy resin led to the formation of well dispersed uniform blend morphology and imparted enhanced thermostability and ductility to the blends. A brittle-to-ductile transition was observed in the blends.

An architecturally asymmetric polystyrene-block-polybutadiene-block-polystyrene (SBS) triblock copolymer possessing lamellar morphology was subjected to different degrees of epoxidation with performic acid generated in situ by the reaction between hydrogen peroxide and formic acid. The effect of the chemical modification on morphology and mechanical behaviour of the block copolymer was investigated by means of different techniques such as electron microscopy, Fourier transform Infrared (FTIR) spectroscopy, tensile testing and differential scanning calorimetry (DSC). It was found that the microphase separation behaviour and hence the mechanical properties of the materials can be drastically altered via epoxidation of the diene block of the styrene/diene triblock copolymers. DOI: http://dx.doi.org/10.3126/jncs.v28i0.8057 Journal of Nepal Chemical Society Vol.28, 2011 Page 42-47 Uploaded date: May 7, 2013

Summary Composites made of a thermoplastic matrix reinforced by bamboo fibers were obtained by extrusion and injection methods. It was found that the lignin of the bamboo fibers protects them from thermal exposure and prevents their degradation. As a consequence, in spite of the relatively high processing temperatures required for polymer melting, it is possible to obtain composite materials with acceptable properties for specific low-tech applications.

Very long aging times, up to 15,100 h (629 days) at 110°C, were achieved on flame-retardant printed circuit board laminates commonly used in automotive design. This composite was fabricated from glass fibers embedded in an epoxy resin. Aging was performed in an oven under an air atmosphere at a temperature lower than the glass-transition temperature. Temperature-modulated differential scanning calorimetric analysis was used to investigate the influence of such aging on the glass-transition phenomena. A new amorphous phase appeared during aging. By extending the analysis to samples collected at different thicknesses, we demonstrated the existence of a time-dependent gradient of the properties. A skin–core structure was evidenced, and this slowed down oxidation and allowed physical aging to occur in the bulk sample. An exponential law described the variations of the glass-transition of the new external compound. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 786-792, 2013

The temporal technique analysis by a simplex optimization method of isothermal transient depolarization current measurements (Simplex-TSDC) is presented for the study of the glass transition domain of different polymers. The advantage of the present method compared to the classical TSDC is that it gives direct results comparable to the experiment and allows a good estimate of the relaxation time close to the glass transition temperature in dielectric thin films. The present method also allows a direct determination of two relaxation times corresponding to a fast and a slow dynamics; and then confirms the heterogeneous character of the molecular relaxation dynamics.

The construction of "smart" materials able to perform specific functions at the molecular scale through the application of various stimuli is highly attractive but still challenging. The most recent applications indicate that the outstanding flexibility of self-assembled architectures can be employed as a powerful tool for the development of innovative molecular devices, functional surfaces and smart nanomaterials. Structural flexibility of these materials is known to be conferred by weak intermolecular forces involved in self-assembly strategies. However, some fundamental mechanisms responsible for conformational lability remain unexplored. Furthermore, the role played by stronger bonds, such as coordination, ionic and covalent bonding, is sometimes neglected while they can be employed readily to produce mechanically robust but also chemically reversible structures. In this review, recent applications of structural flexibility and molecular motions in self-assembled nanostructures are discussed. Special focus is given to advanced materials exhibiting significant performance changes after an external stimulus is applied, such as light exposure, pH variation, heat treatment or electromagnetic field. The crucial role played by strong intra- and weak intermolecular interactions on structural lability and responsiveness is highlighted.

Summary Chitosan was prepared from shells of locally available fresh water prawns with variation of sodium hydroxide concentration and reaction time. The biopolymer was melt-mixed with a commercially available biodegradable polymer, the poly(butylene adipate-co-terephthalate) (PBAT). The chitosan and blend films were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The glass transition temperature (Tg) and melting point of the materials remained unchanged implying complete incompatibility of the blend components. Kinetic study showed that activation energy of the degradation process, i.e., thermal stability of the blends, decreased with increasing chitosan content in the blends. As the thermal properties of all the samples were found to be identical, it can be concluded that there was no effect of the added chitosan on the crystallization and melting behavior of the PBAT. These findings support the notion of the absence of interactions among the blend components. The rate of biodegradation was found to be higher in blends compared to pure PBAT polymer.

Summary When photo curing a polymer system, one immediately becomes concerned with the depth of penetration of light into the system and how it affects the uniformity of the curing process. The attenuation of light is related to the Beer-Lambert law of light penetration into the system, and its influence on the curing depends on the role of light intensity on the curing kinetics. The attenuation coefficient of the Beer-Lambert law can be measured by direct light power measurements for light passing through different thicknesses of the material. In this article we show how the curing kinetics measured by following changes in the infrared light spectra obtained from rapid-scan FTIR can be used to obtain both the Beer-Lambert attenuation coefficient and the power factor, indicating the nonlinear influence of the light power on the curing process. The method is demonstrated for the photo curing of an acrylate cross-linker, and verified using direct power measurement.

Ultra-violet (UV) laser assisted stereolithography is used to print graded interpenetrating polymer networks (IPNs) by controlling network formation. Unlike the traditional process where structural change in IPNs is achieved by varying the feeding ratio of monomers or polymer precursors, in this demonstration property is changed by controlled termination of network formation. A photo-initiated process is used to construct IPNs by a combination of radical and cationic network formation in an acrylate/epoxy system. The extent of the cationic network formation is used to control the final properties of the system. Rapid-Scan Fourier Transformation Infrared Spectroscopy (RS-FTIR) is used to track the curing kinetics of the two networks and identify key parameters to control the final properties. Atomic force microscopy (AFM) and differential scanning calorimetry (DSC) confirm the formation of homogenous IPNs, whereas nano-indentation indicates that properties vary with the extent of cationic network formation. The curing characteristics are used to design and demonstrate printing of graded IPNs that show two orders of magnitude variation in mechanical properties in the millimeter scale.

Aiming at development of completely biodegradable composite materials based on locally available low-cost bamboo flour (BF) as filler, structure properties correlations in aliphatic–aromatic copolyester/BF composites fabricated by melt mixing have been studied by means of different techniques such as electron microscopy, X-ray diffraction, tensile testing, and thermogravimetric analysis (TGA). It has been demonstrated that the BF can be successfully incorporated homogeneously into the biodegradable polymeric matrix up to high content. The filler weakly adheres to the matrix as demonstrated by the pulling up of bamboo fibers on the electron micrographs and further attested by TGA. At high filler concentration, the polymer acts merely as binding material. The semicrystalline framework of the matrix polymer is hindered by the presence of the fibers, the structural changes being more pronounced at the surfaces than in the bulk, which indicates preferential segregation of the fibers toward the specimen surface. This opens new possibilities for a more detailed engineering of materials surfaces. The mechanical properties of the composites are suited for low-load-bearing applications. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Molecular dynamics at the glass transition of three lactose/oil glassy systems have been investigated according to the cooperativity and fragility approaches. From Donth's approach, the cooperativity length is estimated by modulated temperature calorimetric measurements. Results reveal that modification of the disaccharide by oil leads to increase the disorder degree in the lactose, the size of the cooperative domains and the fragility index. These particular hydrogen-bonded organic glasses follow the general tendency observed on organic and inorganic polymers: the higher the cooperativity length, the higher the value of the fragility index at T g .

This paper reports the effect of glycerol on thermal, mechanical and morphology of the wheat-flour based thermoplastic sheets (

The electrical properties of sisal fiber reinforced polyester composites fabricated by resin transfer molding (RTM) have been studied with special reference to fiber loading, frequency and temperature. The dielectric constant ( e ′), loss factor ( e ″), dissipation factor (tan δ ) and conductivity increases with fiber content for the entire range of frequencies. The values are high for the composites having fiber content of 50 vol.%. This increment is high at low frequencies, low at medium frequencies, and very small at high frequencies. The volume resistivity varies with fiber loading at lower frequency and merges together at higher frequency. When temperature increases the dielectric constant values increases followed by a decrease after the glass transition temperature. This variation depends upon the fiber content. Finally an attempt is made to correlate the experimental value of the dielectric constant with theoretical predictions.

A review of the history of the evolution of material science and material technology shows us that one tendency for the future could be the use of agriculture resources. In this work, we review the performances of one of these resources, that is, wheat flour. We show that it is possible to get thermoplastic films with properties quasiequivalent to what is obtained for expensive pure starch. By adding natural fibres, composites are also obtained. These composites exhibit performances which allow their use only for short duration.

An attempt was made to toughen diglycidyl ether of bisphenol A (DGEBA) type epoxy resin with liquid natural rubber possessing hydroxyl functionality (HTLNR). Epon 250 epoxy monomer is cured using nadic methyl anhydride as hardener in presence of N, N dimethyl benzyl amine as accelerator. HTLNR of different concentrations up to 20 wt % is used as modifier for epoxy resin. The addition HTLNR to an anhydride hardener/epoxy monomer mixture has given rise to the formation of phase-separated structure, consisting of small spherical liquid natural rubber particles bonded to the surrounding epoxy matrix. The particle size increased with increase in rubber content. The viscoelastic properties of the blends were analyzed using dynamic mechanical thermal analysis. The Tg corresponding to epoxy rich phase was evident from the dynamic mechanical spectrum, while the Tg of the rubber phase was overlapped by the β relaxation of epoxy phase. Glass transition of the epoxy phase decreased linearly as a function of the amount of rubber. The mechanical properties such as impact and fracture toughness were also carefully examined. The impact and fracture toughness increase with HTLNR content. A threefold increase in impact strength was observed with 15 wt % HTLNR/epoxy blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Physical aging induced by an exposure of As–Se, As–S, and Ge–Se glasses to the light of different discrete wavelengths is studied using differential scanning calorimetry technique. The value of this effect is compared to the physical aging caused by natural storage in the dark. It is shown that a choice of As or Ge atoms does not influence significantly the spectral dependence of light-assisted physical aging, whereas substitution of Se with S causes drastic changes in the magnitude of the effect. The mechanism of the observed light-induced phenomena is discussed in terms of transient and metastable displacements of network chalcogen atoms.

This article reports the result of the effect of banana fiber on the dynamic mechanical and thermal properties of polyester composites. Composites were prepared using resin transfer molding by varying the fiber content (20, 30, 40, and 50 vol.%). Studies revealed that increase in the fiber content will increase the storage modulus ( E′) and the maximum is given by the composites having a fiber loading of 40 vol.% at all temperature ranges. The peak height of loss modulus ( E″) and damping curves (tan δ) were lowered with respect to the fiber content. Glass transition temperature ( Tg) calculated from the E″ and tan δ shifted toward high temperature with the addition of fiber. An attempt has been made to correlate the experimental and theoretical values of storage modulus and tan δ. Thermogravimetric analysis showed that incorporation of fiber to the matrix will affect the thermal stability of the composites.

Temperature Modulated Differential Scanning Calorimetry (TMDSC) is used to estimate Cooperative Rearranging Region (CRR) average sizes for polymer/clay nanocomposites, obtained by mixing polyethylene 1,4-cyclohexylenedimethylene terephthalate glycol (PETg) filled and organically modified nanoclay (C15A) following a master-batch process. Two different basal distances are obtained. It is shown that the greater the basal distance and the nanofiller content, the lower the heat capacity step at the glass transition temperature ΔCp(Tg), and the lower the CRR volume. It is also shown that the evolution of the CRR volume is consistent with the evolution of the fragility index obtained by DSC and Broadband Dielectric Spectroscopy (BDS) when the nanofiller content changes. The fragility index and the CRR size decreases can be correlated to nanofiller presence, hindering the molecular movements. From the Vollenberg and Heikens [34] approach, this behaviour can also be interpreted through the existence of an interfacial bilayer. This interfacial bilayer is composed by a zone, which is next to the nanofiller, with a density higher than the matrix one, followed by a more expanded zone with a density lower than the matrix one.

Arresting of segmental mobility in polymer systems on cooling from the melt was simulated by means of the Bond Fluctuation Model. In order to represent the behaviour of the system, three potentials were included: a Lennard-Jones potential, a bond length potential and a bond angle potential. The effect of the bond angle and bond length potential combination is to stretch the chains, while the Lennard-Jones potential leads to a lack of free volume which appears when temperature decreases. So, when a cooling ramp is applied, depending on the balance of these potentials, the system shows a transition in which molecules densely pack or, on the contrary, remains amorphous. Therefore, the choice in the weighting of these three potentials is a key point to simulate a physical system by using the Bond Fluctuation Model. © 2010 Elsevier Ltd. All rights reserved., The authors would like to acknowledge the support provided by the Conselleria d'Educacio of the Generalitat Valenciana through the GV/2009/033 project. This work was supported by the computer-time grant (No. 2003014) of the Centre de Ressources Informatiques de Haute Normandie (CRIHAN).

Wheat flour based thermoplastic having glycerol content (20%, 23%, 25%, 30% and 35% w/w) were fabricated using extrusion followed by compression molding. Dynamic mechanical analysis (DMA) has been done with reference to the amount of glycerol, sisal fiber loading, frequency and temperature. Two transitions peaks were observed for the, matrix, one at low temperature, due to the molecular dynamics associated to glycerol rich phase, and another at high temperature attributed to the molecular relaxation of starch rich phase. By changing the amount of glycerol, it has been observed that, at all temperature ranges, a plasticization effect which concerns mainly in the starch rich phase. Introduction of sisal fiber (up to 10% w/w) increases the storage modulus of the thermoplastic matrix. The peak height of damping curves (tan δ ) was lowered as the fiber content. The activation energy was calculated from the maximum temperature ( T max ) of damping curves.