Anhydride/Epoxy Functionalized Blends: Mechanical, Rheological and Thermal Properties

For the purpose of this study is to develop the new engineering materials such as structural materials and tribomaterials (for sliding mechanical parts) based on plant-derived materials with sufficient balance among mechanical, processability, tribological properties, eco-friendliness, etc., we investigated the effect of addition of polytetrafluoroethylene (PTFE) on the rheological and mechanical properties of carbon fiber (CF) reinforced plant-derived semi-aromatic polyamide (PA10T) biomass composites. Especially, the relationship between various physical properties such as rheological and mechanical properties of these biomass composites and internal microstructure in the composites when added with PTFE or not were discussed in this study. PA10T is a kind of polyphthalamide (PPA, semi-aromatic polyamide) biomass polymer made from plant-derived decamethylenediamine and coal-derived terephthalic acid. In this study, PA10T was used as a matrix polymer. CF was used as the reinforcement fiber and its volume fraction was fixed on 20vol.%. PTFE was used as the solid lubricant and its weight fraction was fixed on 20wt.%. Various CF/PA10T/PTFE biomass composites were extruded using a twin screw extruder and injection molded. Rheological properties in the molten state were evaluated by oscillatory flow test using a parallel plate type rheometer. Mechanical properties such as tensile, bending, Izod impact and tribological properties were evaluated. Tribological properties were measured using a ring-on-plate type sliding wear tester at the room temperature under dry condition. The sliding surfaces of the test specimen, wear debris and counterface before/ after observation by a SEM with osmium (Os) sputter coating. To understand the internal microstructure in these biomass composites, the surface of the samples fractured cryogenically in liquid nitrogen was observed using SEM and the fiber length and its distribution were measured for the samples after injection molding.It was found that rheological properties such as storage modulus and complex viscosity of CF/PA10T biomass composites in molten state changed when added with PTFE. Mechanical properties such as strength and modulus of CF/PA10T/PTFE biomass composites are almost the same as those of CF/PTFE biomass composites, although tribological properties such as frictional coefficient, specific wear rate and limiting pv value improved when filled with PTFE. In particular, the limiting pv value of CF/PA10T/PTFE biomass composites remarkably improved due to the results of the synergistic effect, which is both mechanical and tribological properties are improved when filled with both PTFE and CF. These may be attributed to the change in the internal microstructure of these biomass composites such as fiber length, fiber dispersion and fiber-fiber interactions. Therefore, these results may contribute to the development of new engineering materials based on plant-derived polymer composites with sufficient balance among eco-friendliness, processability, mechanical and tribological properties.

The objective of this study was to prepare linear low density polyethylene (LLDPE)/chitosan/closite nanocomposites by using various concentrations of LLDPE, chitosan, and closite clay mineral. The nanocomposites were then characterized for their thermal, mechanical, and rheological properties by using different analytical techniques including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), rheological characterization, tensile strength study, and scanning electron microscopy. The TGA demonstrated that crosslinked composites are thermally more stable than non-crosslinked composites. The DSC stated that the percentage crystallinity of crosslinked composites is lower than the non-crosslinked composites. It is also observed that the increasing quantity of chitosan and closite also reduces the percentage crystallinity of the prepared nanocomposites. Rheological characterization revealed that, crosslinked composites are viscoelastic in nature and have high complex viscosities (η*) and high dynamic shear storage modulus (G′), while non-crosslinked composites showed high dynamic shear loss modulus (G″). Tensile strength of crosslinked composites was much higher than non-crosslinked composites, however elongation at break (Eb) values of non-crosslinked composites are higher than crosslinked composites. The scanning electron microscopy displayed strong adhesion between matrix-filler-interphase in crosslinked composites, while some gaps were also observed in non-crosslinked composites. As a conclusion, chitosan, closite clay, and the LLDPE based nanocomposites with improved thermal, mechanical, and rheological properties can be successfully prepared by employing a peroxide-initiated melt compounding technique.

Different thermoplastic vulcanizate (TPV) blends were prepared from elastomeric chlorosulfonated polyethylene (CSM) and thermoplastic polypropylene (PP) by employing dynamic vulcanization technique. The mechanical properties of such blends were compared in respect of their stress at 25% modulus (25%M), ultimate tensile strength (UTS), percent elongation at break, and hardness to those of pure CSM. The mechanical analysis showed substantial improvement in stress at 25%M, UTS, and hardness values with the incorporation of 15–40 parts of thermoplastic contents (PP) (per hundred parts of blend). The two‐phase morphologies were clearly observed by scanning electron microscopy studies. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC studies showed a decreasing trend in glass transition temperature (Tg) and TGA studies indicated the increase in thermal stability of all TPV blends with respect to the elastomeric CSM. Rheological studies showed that there is an increasing trend in shear melt viscosity of TPV blends with the increase in PP amount as the higher content of isotactic PP used in the present case increases the melt viscosity. The TPVs obtained after the rheotron studies displayed identical shear stress/strain pattern when further subjected to the same study. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Co-Relationship of Mechanical, Thermal and Morphological Properties of PVDF-ZnO Composite Materials

Previous studies suggest that carbon nanotubes (CNTs) have a considerable influence on the curing behavior and crosslink density of epoxy resins. This invariably has an important effect on different thermal and mechanical properties of the epoxy network. This work focuses on the important role of the epoxy/hardener mixing ratio on the mechanical and thermal properties of a high temperature aerospace-grade epoxy (MY0510 Araldite as an epoxy and 4,4′-diaminodiphenylsulfone as an aromatic hardener) modified with single-walled carbon nanotubes (SWCNTs). The effects of three different stoichiometries (stoichiometric and off-stoichiometric) on various mechanical and thermal properties (fracture toughness, tensile properties, glass transition temperature) of the epoxy resin and its SWCNT-modified composites were obtained. The results were also supported by Raman spectroscopy and scanning electron microscopy (SEM). For the neat resin, it was found that an epoxy/hardener molar ratio of 1:0.8 provides the best overall properties. In contrast, the pattern in property changes with the reaction stoichiometry was considerably different for composites reinforced with unfunctionalized SWCNTs and reduced SWCNTs. A comparison among composites suggests that a 1:1 molar ratio considerably outperforms the other two ratios examined in this work (1:0.8 and 1:1.1). This composition at 0.2 wt% SWCNT loading provides the highest overall mechanical properties by improving fracture toughness, ultimate tensile strength and ultimate tensile strain of the epoxy resin by 40%, 34%, 54%, respectively.

In this study, the rheology, morphology and mechanical properties of microfibrillar composites based on polypropylene reinforced with polyamide 6 (PA6) fibres have been investigated. Influence of different factors such as the PA6 composition and drawing ratio on the output of the extruder, and the compatibilizer composition on the properties of these composites, were investigated. The results of rheometric mechanical spectrometer rheological measurements and melt flow index (MFI) showed that the storage modulus, loss modulus and complex viscosity of the microfibrillar composites are directly related to the composition of PA6. It was also shown that the presence of compatibilizer was the main factor that led to decrease of some properties including the storage modulus, loss modulus and complex viscosity and increase in the MFI. The results of mechanical tests on samples prepared with different drawing ratios showed that by increasing the drawing ratio from 3 to 5, the mechanical properties increase, while increasing draw ratio from 5 to 8 reduces the mechanical properties. With the increase in the composition of the polyamide phase, the tensile strength of microfibrillar composite compatible with polypropylene-grafted-maleic anhydride initially increased; however, the tensile strength decreased with a high composition of polyamide phase. Scanning electron microscope images also revealed that the presence of the compatibilizer in the microfibrillar composites leads to decrease in the number of undeformed drops, while it reduces the micro-fibres diameter, which greatly improved the final properties of the composites.

An innovative functional compatibility strategy for poly (lactic acid) and polypropylene carbonate blends to achieve superior toughness, degradability, and optical properties

Manufacturing functionally graded material through 3D printing is challenging owing to the deposition of different materials with different thermal properties in each layer, leading to a higher thermal gradient between deposited and depositing layers, resulting in improper bonding between them and, hence, reduced mechanical properties. This study focuses on 3D printing of functionalized multi‐walled carbon nanotubes (MWCNTs)/high‐density polyethylene (HDPE)‐based lightweight functionally graded nanocomposites (FGNCs) and their investigation for microstructural, rheological, physical, and mechanical properties. Functionalized MWCNTs (0.5% → 5%) are initially compounded with widely utilized HDPE to develop nanocomposites (H0.5→H5 pellets) for extruding filaments for 3D printing. 3D‐printed FGNC samples are investigated through scanning electron microscopy (SEM), rheology, density, tensile, and flexural tests. SEM and rheology confirm the homogeneous dispersion of the filler in HDPE and the processing parameters suitability in blending, extrusion, and 3D printing. Complex viscosity (η*), loss modulus (E″), and storage modulus (E′) of FGNCs increase, while the damping decreases with the MWCNTs rise in the graded layers. Density results revealed the highest weight saving potential (~12%) of FGNC‐2 (H1–H3–H5), showing great weight saving potential. Tensile and flexural properties rise when the MWCNTs content rises in the graded layer. The FGNC‐2 showed the highest tensile strength and moduli, 37.12% and 90.41% higher than HDPE. Flexural strength and moduli are also found to be the highest for FGNC‐2, 28.57%, and 26.83% higher than HDPE. The highest specific moduli and strength are found for FGNC‐2, 46.16% and 44.14% higher than HDPE, respectively. Experimental findings are found to be strongly in agreement with numerical findings. 3D‐printed FGNC‐2 demonstrated the best flexural and tensile characteristics with the lowest weight and hence can be used to make practical parts and structures that need variable stiffness.Highlights FGNCs functionally graded n anocomposites are concurrently 3D printed. FGNC‐2 exhibited the highest weight saving potential of 12%. FGNC‐2 showed 90.41% and 37.12% enhanced tensile modulus and strength. FGNC‐2 displayed 28.57% and 26.83% improved flexural strength and modulus. FGNCs exhibited better mechanical performance than the homogeneous NCs.

This study investigates the mechanical, thermal, and chemical properties of basalt/woven glass fiber reinforced polymer (BGRP) hybrid polyester composites. The Fourier transform infrared spectroscopy (FTIR) was used to explore the chemical aspect, whereas the dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA) were performed to determine the mechanical and thermal properties. The dynamic mechanical properties were evaluated in terms of the storage modulus, loss modulus, and damping factor. The FTIR results showed that incorporating single and hybrid fibers in the matrix did not change the chemical properties. The DMA findings revealed that the B7.5/G22.5 composite with 7.5 wt% of basalt fiber (B) and 22.5 wt% of glass fiber (G) exhibited the highest elastic and viscous properties, as it exhibited the higher storage modulus (8.04 × 109 MPa) and loss modulus (1.32 × 109 MPa) compared to the other samples. All the reinforced composites had better damping behavior than the neat matrix, but no further enhancement was obtained upon hybridization. The analysis also revealed that the B22.5/G7.5 composite with 22.5 wt% of basalt fiber and 7.5 wt% of glass fiber had the highest Tg at 70.80 °C, and increased by 15 °C compared to the neat matrix. TMA data suggested that the reinforced composites had relatively low dimensional stabilities than the neat matrix, particularly between 50 to 80 °C. Overall, the hybridization of basalt and glass fibers in unsaturated polyester formed composites with higher mechanical and thermal properties than single reinforced composites.

Assessing changes on poly(ethylene terephthalate) properties after recycling: Mechanical recycling in laboratory versus postconsumer recycled material

ABSTRACTAlthough additive manufacturing through melt extrusion has become increasingly popular as a route to design scaffolds with complex geometries the technique if often limited by the reduction in molecular weight and the viscoelastic response when degradable aliphatic polyesters of high molecular weight are used. Here we use a melt extruder and fused filament fabrication printer to produce a reliable nondegradative route for scaffold fabrication of medical grade copolymers of L‐lactide, poly(ε‐caprolactone‐co‐L‐lactide), and poly(L‐lactide‐co‐trimethylene carbonate). We show that degradation is avoided using filament extrusion and fused filament fabrication if the process parameters are deliberately chosen based upon the rheological behavior, mechanical properties, and polymer composition. Structural, mechanical, and thermal properties were assessed throughout the process to obtain comprehension of the relationship between the rheological properties and the behavior of the medical grade copolymers in the extruder and printer. Scaffolds with a controlled architecture were achieved using high‐molecular‐weight polyesters exhibiting a large range in the elastic response causing negligible degradation of the polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48550.

Impact of nano-silica on Thermal, Mechanical, and rheological properties of melt-extruded PLA-based nanocomposites.

Chemical foaming extrusion of poly(lactic acid) with chain-extenders: Physical and morphological characterizations

Influence of thermoplastic polyurethane (TPU) and printing parameters on the thermal and mechanical performance of polylactic acid (PLA) / thermoplastic polyurethane (TPU) polymer

A commercial grade of high density polyethylene (HDPE) matrix reinforced with nylon fibre up to 30 wt-% of HDPE was studied as a potential candidate for recyclable composites. These composite materials show improvement in mechanical properties such as tensile strength and flexural strength. Modification using styrene maleic anhydride – grafted HDPE significantly improved the mechanical and thermal properties. The HDPE/nylon composites/blends obtained by recycling of the composites also show good mechanical properties.