Dynamic Mechanical Properties Of Poly Research Articles

Effect of coconut fibers chemically modified with alkoxysilanes on the crystallization, thermal, and dynamic mechanical properties of poly(lactic acid) composites

Effect of coconut fibers chemically modified with alkoxysilanes on the crystallization, thermal, and dynamic mechanical properties of poly(lactic acid) composites

Combined digestion and bleaching of New Zealand flax /harakeke fibre and its effects on the mechanical, thermal, and dynamic mechanical properties of poly(lactic) acid matrix composites

In this study, New Zealand flax (harakeke) fibre was initially modified through digestion in an alkali solution followed by bleaching with hydrogen peroxide and sodium silicate with the aim of improving thermal and mechanical performance of its composites, through increased interfacial bonding. X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy and lignin analysis showed that the combination of bleaching and alkali treatment resulted in a higher cellulose content than digestion alone. Fibre inclusion was found to increase the crystallinity of PLA, likely due to heterogeneous nucleation on the treated fibres, which in turn helped to improve the composite strength. The highest tensile strength, tensile modulus and thermal stability were achieved with the bleached fibre which is believed to be due to better fibre distribution and stronger interfacial interaction. This was supported by the adhesion factor and effectiveness coefficient calculated using the data obtained from dynamic mechanical analysis.

Viscoelastic Properties of Water-Absorbed Poly(methyl methacrylate) Doped with Lithium Salts with Various Anions.

We investigated the effects of water absorption on the dynamic mechanical properties of poly(methyl methacrylate) doped with various generic lithium salts, such as lithium perchlorate trihydrate (LiClO4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium nonafluorobutanesulfonate (LiC4F9SO3), and lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)). The rates of weight change during water absorption of lithium salt-doped samples were higher in the following order: LiClO4, LiCF3SO3, LiC4F9SO3, and LiN(CF3SO2). Interestingly, the aforementioned order was the same as the order of the terminal relaxation times in the flow region of the viscoelastic measurement in the melting-state. This implies that the water absorption of the salt-doped PMMA occurs due to the factors that affect the pinning of the PMMA molecular chains in the places.

Influence of PA6 particle filler on morphology, crystallization behavior and dynamic mechanical properties of poly(ε-caprolactone) as an efficient nucleating agent

Influence of PA6 particle filler on morphology, crystallization behavior and dynamic mechanical properties of poly(ε-caprolactone) as an efficient nucleating agent

Influence of Glutaraldehyde Cross-linker on Dynamic Properties of Polyvinyl Alcohol Polymer

This study investigated the dynamic mechanical properties of poly(vinyl alcohol) (PVA; (CH2CH(OH)) n ) cross-linked with glutaraldehyde (GA; OHC(CH2)3CHO). The cross-linked polymer was prepared by ...

Influence of Cation and Anion Type on the Formation of the Electroactive β-Phase and Thermal and Dynamic Mechanical Properties of Poly(vinylidene fluoride)/Ionic Liquids Blends

Films based on poly(vinylidene fluoride) (PVDF) blended with ionic liquids (ILs) comprising different cations and anions were developed to investigate the IL influence on the resulting PVDF crystal...

Effect of hybrid filling with short glass fibers and expanded graphite on structure, rheological and mechanical properties of poly(ethylene terephthalate)

Effect of short glass fibers (GF), added as roving, and thermally expanded graphite (EG) on structure, rheological, static and dynamic mechanical properties of poly(ethylene terephthalate) (PET) is studied. The materials were compounded by reactive extrusion using a co-rotating twin screw extruder with a sectional design of the material barrel in presence of 0.9 wt% of a diisocyanate chain extender. It is established that fragmentation of GF in the grinding section is accompanied with an intensified dispersion of EG, enhanced with the increasing concentration of GF, while addition of EG promotes an increase in the mean length of GF. Increasing content of the fillers intensifies degradation of PET macromolecules, accompanied by a decreasing molecular mass, increasing melt flow rate, crystallization rate and degree of crystallinity. The modulus of elasticity of the hybrid composites is found to increase synergistically which is attributed to inter-dependent changes in the fillers’ dispersity – enhanced dispersion of EG and retarded decrease of the mean GF length compared to the single filler composites.

An investigation on the role of GMA grafting degree on the efficiency of PET/PP-g-GMA reactive blending: morphology and mechanical properties

Glycidyl methacrylate (GMA) has been grafted on polypropylene (PP) with the aid of styrene (St) comonomer, by changing dicumyl peroxide initiator content, GMA level, and St concentration. The performance of the resulting PP-g-GMA reactive material towards static and dynamic mechanical properties of poly (ethylene terephthalate) (PET) was monitored in terms of grafting reaction variables and compatibilizer content. Fourier transform infrared spectroscopy, scanning electron microscopy, mechanical properties, melt flow rate, and impact strength analyses were applied to correlate structural changes due to grafting (or undesired chain scission) with blends’ properties. The competition between the desired reaction, i.e., GMA grafting onto PP chain, and undesired chain scission of PP macroradicals due to thermal degradation, was discussed based on torque–time curves and mechanical properties. Manipulation of grafting variables was responsible for a special behavior over properties, means that optimal or ascending/descending trends, which noticed high sensitivity of PET toughening to GMA grafting efficiency.

Non‐isothermal crystallization kinetics and dynamic mechanical properties of poly(Butylene succinate) nanocomposites with different type of carbonaceous nanoparticles

In this article, the influence of type of carbon‐based nanofillers such as carbon nanotubes (CNT), carbon‐black (CB), and fullerene (F), on the non‐isothermal crystallization kinetics of poly(butylene succinate) (PBS) was investigated. The particle geometry of the nanofillers was focused. The filler content was 0.5% and 1.0% by weight. The nanocomposites were processed in a laboratory twin screw compounder. The spherulitic morphology and crystal‐growth were observed with a hot stage polarized optical microscopy. The structure of nanocomposites in the nanometer scale was characterized using transmission electron microscopy (TEM). The influence of nanofillers on the mechanical properties of PBS nanocomposites was measured by using dynamical mechanical analysis (DMA). The investigation of non‐isothermal crystallization kinetics was performed by using differential scanning calorimetry (DSC) at four different cooling rates (5, 15, 25, and 50°C/min). Analysis of melt crystallization data obtained was performed at a wide range of cooling rates with Avrami, Ozawa, and the combined Avrami–Ozawa models. The combined Avrami–Ozawa method could adequately describe the primary stage of non‐isothermal crystallization of the neat PBS and PBS nanocomposites. It was shown that nanocomposites including CNT particles represented the highest nucleation ability in comparison to fullerene and carbon‐black. Conversely, despite the fact that CNT exhibited a dominant heterogeneous nucleating efficiency, its performance in crystallization rate was contradicted. This interesting phenomenon indicated that the impeding effect of CNT particles during crystallization was stronger than its nucleation efficiency. The order of nucleation activity of each nanofiller from the lowest to the highest was as CNT > F > CB. POLYM. COMPOS., 39:2705–2721, 2018. © 2016 Society of Plastics Engineers

Dynamic mechanical relaxations of electrospun poly(acrylonitrile-co-methyl acrylate) nanofibrous yarn

The phase structure and dynamic mechanical properties of poly(acrylonitrile-co-methyl acrylate) (P(AN-co-MA)) nanofibers collected in the form of twisted yarn via the two-nozzle conjugated electrospinning method were investigated to study the effects of solution concentration and take-up velocity on the relaxation behavior of nanofibers yarn. The wide-angle X-ray diffraction analyses of P(AN-co-MA) nanofibers show a two-phase structure of nanofibers consisting of crystalline and amorphous phases and polymorphic transition from hexagonal to orthorhombic. Heating P(AN-co-MA) nanofibers at over the glass transition temperature led to an increased degree of both crystallinity and crystallite size with no polymorphic change. Three transitions (tan δ peaks) were observed in nanofibrous yarn prepared at different spinning dope concentrations and take-up speeds, except for the specimen prepared at a concentration of 14 wt% and collecting speed of 8 cm/min, wherein no α transition was observed due to improved molecular orientation. The temperature dependence of the dynamic Young’s modulus of nanofibrous yarn at different spinning dope concentrations was mainly affected by the diameter of the nanofiber as the morphological property and molecular orientation. Take-up speed was found to affect the γ and α transitions more than the β transition. Moreover, the maximum storage modulus was obtained at a take-up speed of 8 cm/min at all over recorded temperatures.

Static and Dynamic Mechanical Properties of Poly (vinyl chloride) and Waste Rice Husk Ash Composites Compatibilized with γ-aminopropyltrimethoxysilane

In this paper, γ-aminopropyltrimethoxysilane treated poly(vinyl chloride) (PVC)/rice husk ash (RHA) composites were successfully prepared by a reactive extrusion process. Experimental results revealed that both the tensile modulus and tensile strength increased at all silane coupling agent concentrations. The composites with 1 wt% silane exhibited the highest impact strength with 44 % increment. For the untreated composites, poor interfacial adhesion between PVC and RHA was clearly observed. Below the glass transition temperature (Tg), the silane induced higher storage modulus (E ′) but it seemed to be independent of E′ above Tg. Total water absorption at 90 days reduced by 38 % when the silane was added at 1 wt%, which confirmed that some voids were eliminated.

Effects of electrically inert fillers on the properties of poly(m-xylene adipamide)/multiwalled carbon nanotube composites

The effects of three types of electrically-inert fillers, calcium carbonate (CaCO3), talc and glass fiber (GF), on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly(m-xylene adipamide) (MXD6)/multiwalled carbon nanotube (MWCNT) composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO3, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.

Synthesis and characterization of the polyols by air oxidation of soybean oil and its effect on the morphology and dynamic mechanical properties of poly(vinyl chloride) blends

ABSTRACTThe use of natural additives, with low toxicity and good compatibility, for PVC is becoming increasingly attractive. In this study, soybean oil additives were prepared by air oxidation reactions and blending with PVC. The oxidation reaction produced a significant increase in the number of hydroxyl groups in soybean oil; however, this kind of reaction results in the formation of a heterogeneous structure due to free radical reactions in the medium. The oxidized soybean oil improved the compatibility with PVC due to an increase in the number of polar groups, such as hydroxyls, and thus a reduction in the amount of atactic polymer was observed. Furthermore, an increase in the molecular weight of the oxidized oil, as well as large amounts of polar groups contributes to reducing the migration of oil in the PVC. Regarding the crystallinity of PVC, the use of pure and oxidized soybean oil causes small changes in the crystalline phase of the polymer. Oxidized soybean oil has great potential for usage as a secondary plasticizer for PVC. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42102.

Mechanical Characterization of PMMA/MWCNT Composites Under Static and Dynamic Loading Conditions

The aim of this paper is to evaluate quasi-static and dynamic mechanical properties of Poly (methyl methylacrylate) (PMMA)/Multi Walled Carbon Nanotubes (MWCNTs) composites for different compositions of MWCNTs in PMMA by using nano-scale characterization technique. Enhancing the strength of PMMA using various compositions of MWCNTs can enhance its scope of applications where resistance to external static and dynamic load is required. Composites of PMMA/MWCNTs were fabricated using simple solution mixing with various MWCNT compositions (2.5wt%, 5wt% and 10wt%) in PMMA. They were then characterized to obtain quasi static mechanical properties like hardness and elastic modulus using a nanoindentation. It was observed that hardness and modulus for 5wt% MWCNT composition in PMMA/MWCNT composites were enhanced by 44% and 27% respectively in comparison to pure PMMA. However, hardness and elastic modulus for 10wt% PMMA/MWCNT composites reduced by nearly 28% and 23% respectively in comparison to 5wt% PMMA/MWCNT composite. The visco-elastic nature of PMMA/MWCNT composites was also investigated by using Dynamic Mechanical Analysis(DMA). Complex storage modulus for 5wt% PMMA/MWCNT composite and pure PMMA specimen was compared in dynamic mode for a frequency range between 50Hz and 210Hz. It was observed that modulus for 5wt% PMMA/MWCNT composite increased for the complete loading frequency range.

Thermal and dynamic mechanical properties of grafted kenaf filled poly (vinyl chloride)/ethylene vinyl acetate composites

The effects of kenaf and poly (methyl methacrylate grafted kenaf on the thermal and dynamic mechanical properties of poly (vinyl chloride), PVC and ethylene vinyl acetate, EVA blends were investigated. The PVC/EVA/kenaf composites were prepared by mixing the grafted and ungrafted kenaf fiber and PVC/EVA blend using HAAKE Rheomixer at a temperature of 150°C and the rotor speed at 50rpm for 20min. The composites were subjected to Differential Scanning Calorimetric (DSC), Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) and Scanning Electron Microscopy (SEM) studies. The DSC data revealed that the crystallinity of the EVA decreased with the addition of 30% grafted and ungrafted kenaf fibers. TGA and derivative thermogravimetric (DTG) curves displayed an increase in the thermal stability of the composites upon grafting of the fiber. Studies on DMA indicate that the Tg of the PVC and EVA in the PVC/EVA/kenaf composites has been shifted to higher temperature with the addition of the kenaf fiber. The presence of PMMA on the surface of grafted kenaf fiber was further confirmed by the analytical results from FTIR. The morphology of fractured surfaces of the composites, which was examined by a scanning electron microscope, showed the adhesion between the kenaf fiber and the PVC/EVA matrix was improved upon grafting of the kenaf fiber.

Crystallization Behavior and Dynamic Mechanical Properties of Poly(l-Lactic Acid) with Poly(Ethylene Glycol) Terminated by Benzoate

Effect of the addition of poly(ethylene glycol) terminated by benzoate (PEG-BA) on the crystallization behavior and dynamic mechanical properties of poly(l-lactic acid) PLLA is studied as compared with poly(ethylene glycol) (PEG-OH). It is found that PEG-BA is miscible with PLLA and shows good plasticizing effect. Because PEG-OH having the same degree of polymerization is immiscible with PLLA, the end group in PEG-BA, i.e., benzoate, plays an important role in the miscibility. Furthermore, PEG-BA does not induce the PLLA degradation at melt-processing, whereas PEG-OH leads to the hydrolysis degradation. Finally, the addition of PEG-BA pronounces the crystallization rate of PLLA at low crystallization temperatures and thus enhances the degree of crystallinity at conventional processing. Consequently, the temperature dependence of dynamic mechanical properties are similar to that for isotactic polypropylene.

Abrasion Properties and Thermal Stabilities of Poly(vinyl chloride)/Diatomite Composites

Mechanical properties, abrasion properties, thermal stabilities, and dynamic mechanical properties of poly (vinyl chloride) (PVC)/diatomite composites with different diatomite content prepared by melting blending were investigated. The results indicated that mechanical properties of composites have different performance due to diatomite participation, and the flexural modulus was improved. With an increase in diatomite, the abrasion resistance and thermal stability of composites were improved. Furthermore, the E' and Tg of composites could be enhanced effectively with diatomite participation. The optimum combined properties of PVC/diatomite composite were obtained with the adding of 40 phr diatomite.

Effect of the number of methyl groups of the ionic repeat unit on the dynamic mechanical properties and morphology of poly(styrene-co-acrylate)-based ionomers

The dynamic mechanical properties of poly(styrene-co-Na tiglate) PSTANa, poly(styrene-co-Na methacrylate) PSMANa, and poly(styrene-co-Na acrylate) PSAANa ionomers were investigated to know the effect of the number of methyl groups of the acrylate unit on the mechanical properties and morphology of those ionomers. It was found that the ionic modulus of the PSTANa ionomers was much lower than that of the PSMANa ionomer but slightly lower than that of the PSAANa ionomers of comparable ionic unit content. The matrix and cluster Tg's of the PSTANa ionomers were also found to be lower than those of the PSMANa and PSAANa ionomers. The PSTANa ionomers showed a very weak, broad shoulder-like feature at very small angles of X-ray diffraction or scattering profiles. Thus, it was suggested that the presence of two methyl groups on the alpha and beta carbons of an acrylate unit might induce the high energy barrier for the bond rotation, which made the formation of the multiplets difficult; therefore, the PSTANa ionomers became less clustered materials than the PSMANa and PSAANa ionomers.

Dynamic mechanical properties of polystyrene‐co‐styrenesulfonic acid copolymers neutralized with aliphatic diamines

AbstractIn this article, we reported the effects of the addition of various aliphatic diamines (ADAs) on the dynamic mechanical properties of poly(styrene‐co‐styrenesulfonic acid) copolymers. It was found that the ionic modulus decreased with increasing chain length of ADAs but increased for the ADA12‐containing ionomers. Upon the neutralization of the copolymers with ADAs, a minor change in the size and position of the matrix loss tangent peak was observed. However, the position of the cluster loss tangent peaks shifted to lower temperatures, and the shift rate depended on the chain length of ADAs. Thus, it was suggested that the ADAs acted mainly as preferential plasticizer for the cluster regions. In addition, the effect of the amount of ADA on the difference between the matrix and cluster temperatures of the ionomers was strongest than that of the type of ADA or ion content. The X‐ray peak of ADA12 suggested that the ADA12 acted both as plasticizer and as filler. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Correlations between alkyl side chain length and dynamic mechanical properties of poly(n-alkyl acrylates) and poly(n-alkyl methacrylates)

In the present paper, dynamic mechanical properties of poly(n-alkyl acrylates) (PnAA) and poly(n-alkyl methacrylates) (PnAMA) with different alkyl side chain length were studied. The results show that with the increase of alkyl side chain length, the storage modulus changes more steadily, and the loss modulus peak and the tan δ peak become broader for PnAA and PnAMA. At the same time, the tan δ peak is more and more apart from the loss modulus peak and the point where the storage modulus begins to drop. For quantitative discussion, three variables, the steepness index ( S), the transition wideness ( W) of storage modulus and the integration area ( A) of tan δ were defined to investigate the potential correlation between the dynamic mechanical properties and alkyl side chain length. It can be observed that S decreases while W and A increase with increasing alkyl side chain length. Moreover, the relaxation spectra of the two series of polymers are calculated from the corresponding mechanical spectra. The shapes of the relaxation spectra are broader and broader with the increase of the alkyl side chain length. These phenomena are interpreted by the perspective of fragility, molecular packing efficiency and intermolecular coupling.