Mechanical Properties Of Polymer Films Research Articles

Carbon nanocone mechanical behavior and their use as AFM tips for the characterization of polymers in Peak Force mode

Compared to carbon nanotube-based Atomic Force Microscopy probes, carbon nanocone-based probes appear as promising candidates for investigating topography and mechanical properties thanks to the reduced number of artefacts. In this paper, we intend to investigate some of the mechanical features of carbon nanocone (CnC) tips and to evaluate their performances as probes for investigating the mechanical properties of polymer films and composites. Using their force distance curve, the cantilever/CnC spring constant of several CnC probes is determined and the related bending force for each cone is extracted. The results demonstrate CnC bending forces ranging from 100 nN up to 3 μN, which is up to 2 orders of magnitude higher than values reported in the literature for carbon nanotubes. Moreover, the bending phenomenon occurred only when the CnC axis was not strictly perpendicular to the substrate surface. Using Peak-Force Quantitative NanoMechanical (PF-QNM) mode, we demonstrate that CnC probes are suitable to accurately probe polymer mechanical properties, provided the same targeted deformation is used for both the calibration and PF-QNM measurements.

THE APPLICATION OF HYBRID PIGMENTS IN THE FORMATION OF A POLYMER-MINERAL COATING FOR LEATHER FINISHING

The paper is focused to the study of the physical and mechanical properties of a polymer-mineral coating based on hybrid pigments for leather finishing. The aim of this research is to study the effect of hybrid pigments based on montmorillonite on the formation of a polymer-mineral coating for leather finishing. Hybrid pigments obtained by complex modification of native montmorillonite with sodium carbonate and basic chromium (III) sulfate with further subsequent adsorption of anionic dyes on the cationic surface of the mineral particles were used for this research. A ready-made mixture of various structures film-formers, intended for the finishing of facial and polished leather was used as a film-former. For the leather finishing, coating paints were prepared in the form of polymer-mineral compositions by mixing hybrid pigments with a film-forming agent in the ratio, wt. part 1: 5. In this study it was calculated that montmorillonite consumption at the level of 1.5-2.0% in terms of the mass of montmorillonite from the mass of dry polymer residue was optimal for obtaining high physical and mechanical properties of polymer films for finishing leather. A mechanism for structuring the polymer matrix with a hybrid pigment was proposed. According to this mechanism the highly developed sorption surface of montmorillonite provided adsorption of the polymer and stabilized its structure with the formation of a mixed polymer-mineral composite. It was shown that the use of montmorillonite in the composition of hybrid pigment allowed to adjust the physical and mechanical properties of the polymer-mineral composition for leather finishing, provided an increase in strength and regulated the level of elasticity of the covering film, which ensured an increase in the operational properties of the leather coating.

Accelerated aging studies of the selected commercial films

The Arrhenius method was used to investigate the effect of accelerated aging conditions on the physical and mechanical properties of polymer films for technical, medical, food and office applications. Temperature and UV radiation were taken into account as environmental factors. It was shown that the tested films are more sensitive to thermal degradation than UV radiation. The reduction in tensile strength after thermal aging does not exceed 40%, and in the case of UV radiation, 14%. The estimated lifetime of the tested films is over 5 years.

Thermal and mechanical properties of cationic starch-graft-poly(butyl acrylate-co-methyl methacrylate) latex film obtained by semi-continuous emulsion polymerization for adhesive application

In this work, thermal and mechanical properties of cationic cassava starch-g-poly(butyl acrylate-co-methyl methacrylate) films with different amounts of cationic cassava starch (CCS) were studied. The objective of this work was to substitute a portion the monomers (BA/MMA) by CCS in the copolymer and to investigate the consequent effects on the properties of the polymer latex films (e.g., graft percentage, surface tension, thermal and mechanical properties). The results show that the grafting percentage decreased as the concentration of CCS increased. Thermal and mechanical properties of polymer films showed a direct relationship with respect to the content of CCS used and the grafting percentage. Higher grafting percentage led to improvement of the thermal degradation, which indicated better thermal stability than neat poly(BA/MMA). DSC analysis showed that the Tg of the graft copolymers was a little lower as compared to Tg values of un-grafted copolymers. The addition of CCS increases the tensile, elastic modulus and hardness properties of the polymer film, but the elongation at break decreased dramatically. The optimal CCS contents that maximized not only thermal properties, but also mechanical properties, were 7 and 10 mass%, which are directly related to the grafting percentage and CCS content in the formulation. In addition, these results create a new approach for the application of CCS graft-polymer as an adhesive for wood, paper and shoes insole applications.

Study of the effect of the catalyst on the mechanical properties of RTV grade siloxane

A RTV grade siloxane film with a different percentage of catalyst was obtained. The mechanical properties of polymer films based on RTV grade siloxane are studied, as well as the effect of K-18 catalyst concentration on thickness, strength and ductility the properties of the obtained films was shown.

Superposition-based predictions of creep for polymer films at cryogenic temperatures

The purpose of this study was to examine a novel application of superposition techniques for estimation of mechanical properties of polymer films at extreme cryogenic temperatures (e.g. 4 K). Polymer core films of the electronic laminates, ULTRALAM® 3850HT liquid crystal polymer (LCP) and Pyralux TK185018R (polyimide), were tested on a TA Instruments Q800 dynamic mechanical analyzer in tensile mode to obtain time-dependent creep compliance. Activation energy of flows, Ea, were calculated using an Arrhenius model. All data were accumulated within the range from about 150–293 K. Both polymers were found to have relaxation transitions within this range and predictions therefore initiated from the colder side of the transition. Predictive equations are proposed for creep compliance of these polymers. These compliances will be useful for overall failure models associated with devices ranging from electronics to magnetic cavities.

Time and space dependence of large-scale synthesis of colloidal particle with special morphology and tuneable polymer film architecture

This paper describes a facile method to control the morphology of polymer colloids and the architecture of polymer film via miniemulsion polymerization. By taking advantage of cyclization between the symmetrical diacrylate cross-linker hexamethylene diacrylate (HDDA) and the pendent vinyl in colloidal particles, the morphology of polymer colloids and the architecture of the after-formed polymer film were able to be well controlled by tuning the loading of cross-linker HDDA and crosslinking time. Four kinds of polymer colloid morphologies and four kinds of film architecture (honeycomb, close-packed, loose-packed, and enhanced-honeycomb) were characterized by TEM. The film formation mechanisms behind them were proposed based on the special and interesting results including Z-average size of the colloidal particles, Mc (molecular weight between crosslinking points) and mechanical properties of polymer film. Our results highly suggested that the morphology of polymer colloids and the polymer film architecture together determine the adhesive properties of the colloidal polymer film. The best of 180°-peel resistance, T-peel resistance and shear resistance of the polymer films were 138.12 N/25 mm, 40.98 N/25 mm and 25.72 N/cm2 at 2.0 phm, 2.0 phm and 0.4 phm with the same crosslinking time of 90 min, respectively. The proposed method is promising to be scaled up for industrial production due to its well adaptability.

Tuning relaxation dynamics and mechanical properties of polymer films of identical thickness.

Using dewetting as a characterization tool, we demonstrate that physical properties of thin polymer films can be regulated and tuned by employing variable processing conditions. For different molecular weights, the variable behavior of polystyrene films of identical thickness, prepared along systematically altered pathways, became predictable through a single parameter P, defined as the ratio of time required over time available for the equilibration of polymers. In particular, preparation-induced residual stresses, the corresponding relaxation times as well as the rupture probability of such films (of identical thickness) varied by orders of magnitude following scaling relations with P. Our experimental findings suggest that we can predictably enhance properties and hence maximize the performance of thin polymer films via appropriately chosen processing conditions.

Self-organization processes in polysiloxane block copolymers, initiated by modifying fullerene additives

Thin films of a polyblock polysiloxane copolymer and their composites with a modifying fullerene C60 additive are studied by atomic force microscopy, Rutherford backscattering, and neutron scattering. The data of atomic force microscopy show that with the addition of fullerene to the bulk of the polymer matrix, the initial relief of the film surface is leveled more, the larger the additive. This trend is associated with the processes of self-organization of rigid block sequences, which are initiated by the field effect of the surface of fullerene aggregates and lead to an increase in the number of their domains in the bulk of the polymer matrix. The data of Rutherford backscattering and neutron scattering indicate the formation of additional structures with a radius of 60 nm only in films containing fullerene, and their fraction increases with increasing fullerene concentration. A comparative analysis of the data of these methods has shown that such structures are, namely, the domains of a rigid block and are not formed by individual fullerene aggregates. The interrelation of the structure and mechanical properties of polymer films is considered.

Waterborne paints containing nano-sized crystalline domains formed by comb-like polymers

Semicrystalline, waterborne copolymer latexes of stearyl acrylate-co-short chain (meth)acrylate (a mixture of methyl metacrylate, n-butyl acrylate, acrylic acid and acrylamide) have been synthesized by using different 2-step polymerization strategies. The effect of monomer composition and polymerization strategies on the crystallinity and mechanical properties of polymer films were investigated. These semi-crystalline latexes were successfully used as binders in paint formulations and the effect of crystallinity and copolymer microstructure on the mechanical properties (e.g. hardness, scrub resistance, etc.) and hydrophobicity of the paint films was studied.

Significant approaches to promote post-cure reaction of bulky polyimides with pendant phthalonitrile unit

Approaches to promote the post-cure reaction of polyimide with pendant phthalonitrile unit (CN-PI) were first realized by introducing of hydroxyl groups via chemical copolymerization or physical blending. The post-cure reaction of the CN-PI was performed at 250 or 300 °C, and monitored by various techniques, such as infrared spectroscopy (IR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). A significant result was found in that the trend of the increasing glass transition temperature T g with nitrile conversion followed DiBenedetto’s equation. This provided a chance to deeply discuss the relationship between molecular structure, segmental mobility, and cure behavior of CNPI. Chemical structure changes and morphology evolution of the polymer during post-cure process were investigated by IR, WAXD, and SEM. The thermal and mechanical properties of polymer films showed it to be a thermally stable and strong material.

Mechanical properties development of sodium alginate films with additives by UV‐radiation processing

AbstractTo improve mechanical properties of polymer films; sodium alginate (SA) films was prepared with ethylene glycol (EG) and photocured. The formulation was prepared at various concentration with EG and photoinitiator (2%) in methanol. The mechanical properties were optimized in case of monomer (EG) concentration, soaking time, and radiation dose of intensities. The highest polymer loading (PL) was 7.1% and tensile strength (TS) of the film was 37.9 MPa were found for 3 min soaking in 5% EG containing formulation at 20th pass of UV radiation; the highest value (22%) of elongation at break (Eb) was obtained at 1 min soaking time at 15th passes of UV doses. The mechanical properties improvement of the films varied acrylic monomers; such as 2‐ethylhexylacrylate (EHA), 1,4‐butanediol diacrylate (BDDA), and trimethylpropane triacrylate (TMPTA) were used as additives (2%) in the optimized formulation. The highest PL (12.7%) and TS (42.2 MPa) of the films are at 5% EG, 2% TMPTA, and 2% photoinitiator in methanol at 3 min soaking time at 20th pass of UV radiation. The highest Eb (25%) was obtained using additives 2% EHA additives in 5% EG and 2% photoinitiator in methanol at 3 min soaking time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Novel Aromatic Polyimides Derived from 5′-t-Butyl-2′-pivaloylimino-3,4,3′′,4′′-m-terphenyltetracarboxylic Dianhydride with Potential Application on Gas Separation Processes

A new family of polyimides having two bulky groups in the central ring of a m-terphenyl moiety has been obtained. These polyimides have been synthesized by reaction of four commercial diamines with the electrophilic monomer, 5′-t-butyl-2′-pivaloylimino-3,4,3′′,4′′-m-terphenyltetracarboxylic acid dianhydride (PTPDA). This monomer has been obtained by a modern C−H-activated arylation method with good yield and purity. The attained polymers showed Tg values ranging from 300 to 430 °C, thermal stability >500 °C, and excellent solubility in a broad range of solvents, including tetrahydrofuran. Despite having an amide group, uptake of water was low and comparable to that of classical aromatic polyimides. Mechanical properties of polymer films were good enough to permit the use of these polyimides on gas separation applications at high pressures. Films obtained by casting offered a good balance of permeability and permselectivity with values close to the Robeson upper-bound, in particular for the O2/N2 gas pair.

Adhesion in polypropylene/aluminum laminates made by extrusion coating

AbstractThe purpose of this article is to study how processing parameters can promote adhesion in grafted polypropylene/aluminum laminates made by extrusion coating. The density of bonds created at the interface is quantified by X‐ray spectroscopy after dissolution of the polymer film. dynamic mechanical analysis (DMA) and tensile tests are performed to characterize the mechanical properties of polymer films. They are linked with the crystalline structure, as revealed by optical microscopy and X‐ray diffraction. A numerical model of extrusion coating is used to quantify the impact of cooling conditions on adhesion. A good correlation is found between the temperature history, the formation of bonds, and the mechanical properties of the polymer films. High temperature conditions can improve adhesion by increasing the open time for the reaction and the rate of the chemical reaction between grafted polymer chains and aluminum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

極低温タンク構造への適用に向けた樹脂フィルム付きＣＦＲＰ積層板の損傷挙動に関する研究

Polymer films are expected to be feasible candidates for the liner of cryogenic composite tank structures. This study investigates the damage behaviors of polymer-lined CFRP laminates under tensile loading at room and cryogenic temperatures. Because matrix cracks in CFRP laminates are considered to be more susceptible to formation than polymer film fracture, damage behaviors of polymer films beyond the onset of matrix cracks in layers adjacent to polymer film are the major concerns herein. Specimens consisting of polymer films and cross-ply laminates were prepared by co-curing and subjected to tension load. Penetration of matrix cracks in composite layers into polymer films was observed in the case of thermoplastic polyimide-lined CFRP laminates, while crack deflection into interfaces between CFRP and polymer films was observed in the case of liquid crystalline polymer and polyimide films. Finally, mechanical properties of polymer films and adhesive properties between CFRP and polymer films were measured in order to discuss the crack penetration/deflection behaviors in polymer-lined CFRP laminates. An energetic criterion on crack penetration/deflection including the effects of residual thermal stress was applied to the present experimental results, and suitable polymer characteristics were clarified.

Mechanical properties of polymer films used in in-mould decoration

Abstract This paper details an investigation into the mechanical behaviour and capabilities during the forming process for pure polycarbonate (PC) film and films made from blends of polycarbonate with polyesters (polybutylene terephalate (PBT) and polyethylene terephalate (PET)) as used in the in-mould decoration (IMD) process. Using tensile testing and dynamic thermal mechanical testing, the films were tested over a range of temperatures and rates of strain, as employed in the various forming methods. At ambient temperature, the blended films had a greater natural draw ratio and were capable of greater elongation before fracture than pure polycarbonate film. This makes them more suitable for cold forming. Recovery of ambient temperature deformation was most apparent in pure polycarbonate film and PC/PBT. PC/PET showed the least recovery. This suggests that “spring back” will be most apparent in parts formed from polycarbonate and least apparent in parts formed using PC/PET films. Significant heat was generated in the film during tensile strain at high rates; this may have contributed towards thermal softening. The polycarbonate blends showed a more rapid response to temperature increase due to the greater molecular flexibility of the polyester component. When heated the blended films were significantly weaker than pure polycarbonate films and capable of greater elongation, therefore allowing lower forming temperatures to be used. The constituent polymers and their ratios in the blend govern the glass transition temperature and the extent of the associated fall in storage modulus. Greater molecular flexibility reduces the glass transition temperature of the amorphous phase but increases the likelihood of crystallisation thus reducing the extent of the amorphous phase and associated drop in storage modulus over the glass transition.

Calculation of number of tractions forming at macrodestruction of polymer films

Analysis of mechanical properties of polymer films is carried out for different ways of deformation including scaling and pulling off. An expression is obtained for the number of tractions, which may arise in a polymer film at various deformations.

アクリルポリマーをブレンドしたエポキシ硬化フィルムのドメインサイズと力学的特性の関連性

ドメイン構造を有するフィルムの力学的特性を調べた。アミン硬化エポキシフィルムのドメインサイズを添加するアクリルポリマーの分子量, 官能基, 撹拌温度, 相溶化剤の有無によりコントロールした。ドメインサイズは位相差顕微鏡観察した画像のデジタル処理画面から評価し, フィルムの引張り特性, 応力緩和特性との関連性を調べた。ドメインサイズが小さくなるほど破断のび率が増加し, 応力緩和時間が短くなることがわかった。

Effects of electron-beam irradiation on some mechanical properties of polymer films

Effect of the electron-beam irradiation on the tensile strength at break, elongation at break, and tear resistance for packaging films made of low-density polyethylene (LDPE), biaxially oriented polypropylene (BOPP), and polyethylene terephthalate (PET) is discussed. The measurements in both the machine direction and the transverse direction were made. It was found that the electron irradiation caused an increase in the tear resistance of the LDPE film when doses of up to 100 kGy were applied. A significant decrease and even loss of the tear resistance of the films of BOPP and, partially, PET were observed at doses already below 25 kGy. This indicates that the BOPP and PET films when modified with the electron radiation can hardly be used in packaging.

Time-Dependent Mechanical Properties of Polymeric Coatings Used in Rupturable Pulsatile Release Dosage Forms

The mechanical properties of polymer films used in pharmaceutical coatings of pulsatile drug delivery systems were evaluated in the dry and the wet state by a newly developed puncture test, which allowed the time-dependent measurement of the mechanical properties on the same film specimen. Force, puncture strength, energy at break, modulus, and strain were investigated as a function of water exposure time with respect to the type of polymer and the type and concentration of plasticizer and pore former (hydroxypropyl methylcellulose, HPMC). Eudragit® RS films were very flexible, had a high strain, and broke upon puncture with only small cracks. In contrast, ethylcellulose films were more brittle with a lower strain and showed complete film rupture. Increased amounts of the hydrophilic pore former, HPMC, resulted in a reduced puncture strength and in an increase in water uptake and weight loss of the films. The puncture strength decreased with increasing plasticizer concentration and was lower with the lipophilic dibutyl sebacate than with the hydrophilic triethyl citrate.