Effect of water on the mechanical properties of collagen films

The effect on water on mechanical properties of collagen films has been studied. The S-shaped sorption isotherm is separated into an adsorption curve C₁ and a solution curve C₂. From the C₂ curve, a value of 0.8 is calculated for the Flory-Huggins interaction parameter χ₁. The dynamic shear modulus G′, loss modulus G″, and loss tangent tan δ determined as functions of water content indicate two dispersions at low and at high water content. The region of water content from about 0.05 to 0.1 g/g, G′ decreases suddenly, G″ has a peak, and tan δ increases, corresponds to the region where the C₂ component of sorption becomes detectable. Another dispersion occurs at water contents above 0.2 g/g. A composite curve can be obtained by shifting stress-relaxation curves obtained at different humidities along the log time axis. When only the C₂ component of sorbed water is taken into account, the shift factor a_c is explained by a relation of Fujita and Kishimotos' based on free-volume theory. Shift factor for the relaxation curves of wool fibers, except for an initial part at times of less than 1 sec, are described by the same equation. The parameter β in the equation has the same value of 0.16 for both collagen and wool.     

Effect of sintering temperature on mechanical and microstructural properties of bovine hydroxyapatite (BHA)

The influence of sintering temperature on densification, microstructure and the mechanical properties of bovine hydroxyapatite (BHA), produced by a calcination method, was investigated. Densification and mechanical properties improved with increasing sintering temperature in the range between 1000°C and 1300°C, with optimum properties being obtained at a sintering temperature of 1200°C. The measured mechanical properties indicate that sintered BHA bodies are interesting biomaterials for further investigation in biomedical applications.     

The effect of preparation temperature on the mechanical and antibacterial properties of poly(vinyl alcohol)/silver nitrate films

There has been a growing interest in developing antibacterial polymeric materials. The logical consequence following development of a new material is optimisation of its processing conditions and investigation of the influence of processing parameters on functionality of a given material. The present work deals with investigation of the effect of preparation temperature on the mechanical and antibacterial properties of polymer films based on poly(vinyl alcohol) (PVA) and silver nitrate (0, 1, 3, 5, 7, 9 wt.% silver content). The mechanical properties of the films prepared at various temperatures (25, 35, 50, 60, 75 °C) were characterized by using stress-strain analysis. Antibacterial properties were determined by using an agar diffusion test and a dilution and spread plate technique against both Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae). The results show significant effect of the elevated temperature on the samples properties.     

Time-scale- and temperature-dependent mechanical properties of viscoelastic poly(3,4-ethylenedioxythiophene) films

The viscoelastic properties of thin films of poly(3,4-ethylenedioxythiophene) (PEDOT) have been studied using the method of acoustic impedance. The films were deposited on the Au electrodes of 10 MHz AT-cut quartz thickness shear mode resonators and exposed to acetonitrile solutions of 0.1 M TEABF4 and LiClO4. For p-doped films, admittance spectra as a function of potential (E), temperature (T), and time scale (frequency, via harmonics, in the range 10-110 MHz) were acquired. Shear modulus components extracted from these responses surprisingly showed virtually no variation with E (and thus film solvation) or with T, but the variation with frequency was dramatic. This qualitative behavior and the numerical values of the shear moduli contrast strongly with recently reported data for the related poly(3-hexylthiophene) system, which shares the same conducting spine but differs substantially in the substitution pattern. Accordingly, the models and interpretation for PEDOT are quite different: film dynamics are determined by free-volume effects, and side-chain motion is not a significant factor. Qualitatively similar potential and time-scale effects were seen for n-doped PEDOT, but the scope of the measurements was limited by film stability.     

Effect of processing temperature during spin-on application on the properties of sol-gel silica films

The effect of the temperature (of the substrate and the solution) during film deposition on spin coating process of sol-gel films is discussed. The increase of substrate temperature as well as coating solution liquid temperature leads to formation of thicker films with higher porosity. The temperature dependence of films thickness is mainly determined by the change of solvent vapour pressure with consideration for the change of liquid viscosity.     

Superior (de)hydrogenation properties of Mg-Ti-Pd trilayer films at room temperature

In this paper, a series of Mg-Ti-Pd trilayer films with various thicknesses of the Ti interlayer were prepared by magnetron sputtering. The trilayer films could be reversibly (de)hydrogenated at room temperature. The relationship between structure and properties of Mg-Ti-Pd trilayer films was comprehensively investigated. Our studies showed that the hydrogen storage properties of Mg-Pd films were significantly improved with the addition of a Ti interlayer. The optimal hydrogenation properties were obtained when the Ti interlayer was 1 nm. The superior hydrogenation properties achieved by introduction of the Ti interlayer could be attributed to several aspects: prevention of Mg-Pd alloying; catalytic dissociation of H(2) molecules and provision of heterogeneous nucleation sites. These results were elucidative for the development of high performance intermetallic hydrogen storage materials and thin film based functional devices.     

Effect of gamma radiation on the mechanical and barrier properties of HEMA grafted chitosan-based films

Chitosan films were prepared by dissolving 1% (w/v) chitosan powder in 2% (w/v) aqueous acetic acid solution. Chitosan films were prepared by solution casting. The values of puncture strength (PS), viscoelasticity coefficient and water vapor permeability (WVP) of the films were found to be 565 N/mm, 35%, and 3.30 g mm/m² day kPa, respectively. Chitosan solution was exposed to gamma irradiation (0.1–5 kGy) and it was revealed that PS values were reduced significantly (p≤0.05) after 1 kGy dose and it was not possible to form films after 5 kGy. Monomer, 2-hydroxyethyl methacrylate (HEMA) solution (0.1–1%, w/v) was incorporated into the chitosan solution and the formulation was exposed to gamma irradiation (0.3 kGy). A 0.1% (w/v) HEMA concentration at 0.3 kGy dose was found optimal-based on PS values for chitosan grafting. Then radiation dose (0.1–5 kGy) was optimized for HEMA grafting. The highest PS values (672 N/mm) were found at 0.7 kGy. The WVP of the grafted films improved significantly (p≤0.05) with the rise of radiation dose.     

Effect of the aspect ratio of silicate platelets on the mechanical and barrier properties of hydrogenated acrylonitrile butadiene rubber (HNBR)/layered silicate nanocomposites

The role of the aspect ratio of the layered silicate platelets on the mechanical and oxygen permeation properties of hydrogenated nitrile rubber (HNBR)/organophilic layered silicate nanocomposites was investigated. Montmorillonite (MMT) and fluorohectorite (FHT) bearing the same type of intercalant (i.e., octadecylamine; ODA), however, showing different aspect ratio was involved in this study. The dispersion of the layered silicates was assessed by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Increasing aspect ratio (MMT < FHT) resulted in higher stiffness under uniaxial tensile loading. The dispersion state (“secondary structure”) of the organophilic layered silicates reduced dramatically the oxygen permeability of the rubber matrix based on the labyrinth principle. The lowest oxygen permeability was measured for the HNBR/FHT-ODA films in which the layered silicates had the highest aspect ratio. By varying the FHT-ODA volume fraction in the latter compound the mechanical and permeation properties were measured and modelled. It was found that the modified Guth’s and Nielsen’s equations predicted accurately the mechanical and permeation responses, respectively.     

Morphology and mechanical properties of ultra-high molecular weight polyethylene-poly(tetrafluoroethylene) blend films

This paper deals with the morphology and mechanical properties of blend films for polytetrafluoroethylene (PTFE) and ultra-high molecular weight polyethylene (UHMWPE) prepared by kneading techniques. This experiment was carried out for blend films, prepared with different compositions of PTFE and UHMWPE to improve thermal properties of PE. In spite of the incompatibility of the two polymers, the blend film with the PTFE/UHMWPE composition =75/25 was maintained under the measurement of complex modulus at temperature higher than 300°C. This indicates that the UHMWPE chains dispersed in PTFE fibrous texture were not separated by the melting flow of UHMWPE at 300°C. To check the origin of this interesting phenomenon, the morphology of the blend films was investigated by using scanning electron microscopy, X-ray diffraction, and¹³C nuclear magnetic resonance.     

Relative humidity and temperature effects on mechanical and water vapor barrier properties of myofibrillar protein-based films

Fish mince-based films were studied as a function of equilibrium relative humidity and temperature conditions. The sigmoid-shape adsorption isotherm curves were typical of high protein content material and were adequately described, irrespective of temperature, by the Guggenheim-Anderson-de Boer equation. A plasticizing effect of water related to rapid changes in the functional properties was mainly noted at the highest a_w and explained by the disruptive water-polymer hydrogen bonding theory. Relatively sharp decreases in force at break, elastic modulus and water vapor barrier properties, and increases in deformation at break were observed at temperature-dependent relative humidities; this relative humidity was reduced by increasing the temperature. The temperature dependence of the hydration effect on functional properties could be explained by the glass transition theory.     

Dilute solution properties of poly(styrene acrylonitrile) alternating copolymer

Kuhn-Mark-Houwink-Sakurada relations were obtained in methyl ethyl ketone N,N-di-methylformamide and dichlorethane at 30 for (styrene acrylonitrile) alternating copolymer. The values of the unperturbed dimensions. [K₀ or (r_o^?2/M)^1/2] and conformational parameter σ have been determined, using several graphical and semiempirical methods, and the results were compared with the direct determinations in a θ solvent. The best values for K_θ were obtained using the methods of Stockmayer-Fixman and Inagaki-Suzuki-Kurata. By comparing the values of σ for polystyrene, polyacrylonitrile, random and alternating (styrene-acrylonitrile) copolymers, it is to be concluded that the short-range interactions do not markedly influence the chain dimensions in solutions for random and alternating (styrene-acrylonitrile) copolymers.     

Biodegradable polymeric films based on microbial poly(3-hydroxybutyrate). Effect of gamma-radiation on mechanical properties and biodegradability

Two samples of microbial poly(3-hydroxybutyrate) (PHB) having different molecular weight were used for the preparation of films to be exposed to gamma radiation. The effect of radiation on those samples with high molecular weight increased the fragility of the film. Biodegradability increased with time and reached about 95% after 18 days. Weight-loss of both samples (irradiated and non-irradiated) after 23 days were 100%, for those films with molecular weight of 265 kD.     

Effect of 1,1,3-trihydroperfluoro-1-propanol on the properties of poly(ethylene terephthalate) films

Modification of poly(ethylene terephthalate) films with 1,1,3-trihydroperfluoro-1-propanol was performed. Introduction of the modifier favors an increase in the degree of crystallinity and orientation of glycol residues in the trans position, thus improving the operation characteristics of the polyester.     

低聚倍半硅氧烷/聚酰亚胺复合薄膜的力学性能和疏水性能（英文）

具有优良的力学和疏水性能的复合薄膜在惯性约束物理实验中具有重要作用.在本文中,我们使用简单的溶液混合的方法合成了低聚倍半硅氧烷/聚酰亚胺(POSS/PI)复合薄膜.结果表明由于POSS的引入,力学性能和疏水性能显著增强.力学测试结果显示,当POSS质量分数为10%时,弹性模量和硬度分别达到29.29 GPa和29.29 MPa,相比纯的PI薄膜为14.9 GPa和0.64 MPa.同时,当POSS质量分数为20%,复合薄膜的接触角为83.59°,明显高于纯的PI薄膜(66°).因此,POSS/PI复合膜比纯PI薄膜显示了强大的生命力和极其广阔的应用前景在惯性约束聚变(ICF)物理实验中.     

Effect of carbon nanoparticles of different shapes on mechanical properties of aromatic polyimide-based composite films

Nanocomposite films based on thermally stable polypyromellitimide are prepared via the introduction of cylindrical and laminar carbon nanoparticles—nanofibers and nanocones/disks—into the prepolymer solution. An increase in the filler concentration increases the elastic modulus and yield stress of the material. Moreover, in composites filled with nanofibers, both characteristics increase much less intensely than those of films containing nanocones/disks. Rigidity increases in composites filled with nanofibers when their concentration is below ～7 vol %. A further increase in concentration is accompanied by the aggregation of nanofibers. The introduction of the nanoparticles of both types into the polymer matrix stabilizes the behavior of the material under prolonged mechanical loading: both the creep strain and the relaxation intensity decline with an increase in the filler concentration. The introduction of nanocones/disks into the polyimide matrix results in a more pronounced stabilization of creep characteristics of films than that in the case of nanofibers.     

Electrical and mechanical properties of the zone-drawn polypyrrole films

The zone-drawing method (ZD) was applied to electrochemically synthesized polypyrrole films containing tosylate (PPy/TsO) and the mechanical and electrical properties of the resulting films were investigated. It was found that the electrical conductivity of the zone-drawn film reached 365 S cm⁻¹ in the drawing direction, which was 4.7 times that of the original film. The tensile properties of the zone-drawn film were improved and Young's modulus and strength at break increased to 4.32 GPa and 90.1 MPa from 0.53 GPa and 40.4 MPa of the as-synthesized film, respectively. The dynamic storage modulus (E) increased by the zone-drawing over a whole experimental temperature range and attained 7.0 GPa at room temperature and 4.0 GPa even at 200°C. © 1996 John Wiley & Sons, Inc.     

Improved mechanical properties of poly (vinyl alcohol) films with glycerol plasticizer by uniaxial drawing

In this work, the uniaxial stretching poly (vinyl alcohol) (PVA) films with glycerol as plasticizer were prepared to explore the influence of drawing temperature and drawing ratio. The structure and property were investigated with scanning electron microscope, wide‐angle X‐ray diffraction, X‐ray diffraction, differential scanning calorimetry, mechanical tests, etc. With the increase of stretching temperature, the melting and crystallization temperatures increased. The tensile strength and Young modulus of glycerol/PVA films increased first and then decreased; when the temperature was 80°C, the tensile strength and Young modulus reached to maximum values of 197.2 and 470 MPa, respectively. In addition, with the increase of draw ratio, the orientation degree of the PVA molecular chains increased, indicating the improved regularity of molecular chains. When the PVA films were stretched to 4 times, the tensile strength and Young modulus of the films reached 162 and 143 MPa, respectively, which were 4 and 1.3 times compared with those of unoriented films. These environmentally friendly PVA films with excellent mechanical properties would find wide applications in the industry such as packaging, coating, etc.     

Influence of carboxyl‐terminated (butadiene‐co‐acrylonitrile) loading on the mechanical and thermal properties of cured epoxy blends

A mixture of epoxy with liquid nitrile rubber, carboxyl‐terminated (butadiene‐co‐acrylonitrile) (CTBN) was cured under various temperatures. The cured resin was a two‐phase system, where spherical rubber domains were dispersed in the matrix of epoxy. The morphology development during cure was investigated by scanning electron microscope (SEM). There was slight reduction in the glass transition temperature of the epoxy matrix (T_g) on the addition of CTBN. It was observed that, for a particular CTBN content, T_g was found to be unaffected by the cure temperature. Bimodal distribution of particles was noted by SEM analysis. The increase in the size of rubber domains with CTBN content is due probably to the coalescence of the rubber particles. The mechanical properties of the cured resin were thoroughly investigated. Although there was a slight reduction in tensile strength and young's modulus, appreciable improvements in impact strength, fracture energy, and fracture toughness were observed. Addition of nitrile rubber above 20 parts per hundred parts of resin (phr) made the epoxy network more flexible. The volume fraction of dispersed rubbery phase and interfacial area were increased with the addition of more CTBN. A two‐phase morphology was further established by dynamic mechanical analysis (DMA). © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2531–2544, 2004     

Structural and mechanical properties of Laponite-PEG hybrid films

Inorganic/organic hybrids were obtained by the sol-gel type organic modification reaction of Laponite sidewalls with poly(ethylene glycol) (PEG) bearing alkoxysiloxy terminal functionality. By casting an aqueous dispersion of the hybrid, the flexible and transparent hybrid films were obtained. Regardless of the inorganic/organic component ratio, the hybrid film had the ordered structure of Laponite in-plane flat arrays. The mechanical strength of hybrid films was drastically improved by the presence of cross-linking among alkoxysilyl functionalities of PEG terminals and the absence of PEG crystallines. Hybrid films, especially those that consisted of PEG with short chain, showed good mechanical properties that originate from quasi-homogeneous dispersion of components due to anchoring of PEG terminal to Laponite sidewall and interaction of PEG to Laponite surface.     

Effect of (3‐glycidyloxypropyl)trimethoxysilane (GOPS) on the electrical properties of PEDOT:PSS films

Poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) has been reported as a successful functional material in a broad variety of applications. One of the most important advantages of PEDOT:PSS is its water‐solubility, which enables simple and environmental friendly manufacturing processes. Unfortunately, this also implies that pristine PEDOT:PSS films are unsuitable for applications in aqueous environments. To reach stability in polar solvents, (3‐glycidyloxypropyl)trimethoxysilane (GOPS) is typically used to cross‐link PEDOT:PSS. Although this strategy is widely used, its mechanism and effect on PEDOT:PSS performance have not been articulated yet. Here, we present a broad study that provides a better understanding of the effect of GOPS on the electrical and electronic properties of PEDOT:PSS. We show that the GOPS reacts with the sulfonic acid group of the excess PSS, causing a change in the PEDOT:PSS film morphology, while the oxidation level of PEDOT remains unaffected. This is at the origin of the observed conductivity changes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 814–820