Effect on Thermal Properties of Nanocellulose Fibre (NCF) Reinforced Biodegradable Polyhydroxylalkanoates (PHA) Composite

Currently, biodegradable materials like polyhydroxyalkanoates (PHA) and polylactic acid (PLA) are receiving huge attention from the both scientific and industrial sectors. However, since PHA has poor thermal properties, there is a shortfall in the exploration of PHA ability with filler. Therefore, this research aim is to investigate the thermal effect of nanocellulose fiber (NCF) fillers with PHA polymer. The first solution of PHA composite is prepared by dissolving 1g of PHA in 40mL of dichloromethane at 30°C for 10 minutes. The PHA-NCF composite solution is prepared by adding 1wt%, 2wt%, 3wt%, and 4wt% of NCF dissolved in 40 mL of dichloromethane into the PHA solution. The mixture solution is agitated at 45°C with a magnetic stirrer for 10 minutes. The mixture is poured into a petri dish. The prepared films were characterized by Differential Scanning Calorimeter (DSC), Fourier Transforms Infrared Spectroscopy, (FTIR), and Thermogravimetric Analysis (TGA). The FTIR analysis shows that all PHA/NCF composite samples contain similar functional groups when compared with the pure PHA. No significant changes on the thermal properties of the PHA composite was observed with the addition of NCF fillers. However, comparison within the PHA/NCF samples shows that the PHA with 2% of NCF has a higher melting temperature and requires the highest enthalpy of melting. Hence, the addition of 2% of NCF is selected to be the optimum amount of NCF filler addition to the PHA composite.

Effect of coupling agents on the olive pomace-filled polypropylene composite

The effect of the olive pomace flour (OPF) addition on the mechanical, water uptake, morphological, and thermal properties of polypropylene (PP) with and without the use of two coupling agents was investigated. A higher percentage of a coupling agent yielded a greater impact strength of 141 J/m. Tensile and flexural properties of the OPF/PP composite were improved with the two coupling agents. The addition of OPF to pure PP had reduced these properties, thus proving the utility of the coupling agents. While the addition of the OPF to PP increased the water uptake property by 1.36%, the subsequent addition of a coupling agent decreased it to 0.78%. For the neat PP, the enthalpy of melting (∆H m = 123 J/g), the enthalpy of crystallization (∆H c = 133 J/g), and the percent of crystallinity (X c = 59%) values showed a declining trend down to 91, 103 J/g, and 44%, respectively, when the filler and coupling agents added to the composite. The results of this study demonstrated that the OPF could be used as a viable reinforcement for the PP, providing good mechanical and morphological properties, as long as an appropriate coupling agent proportion is added to the composite.

Not all PLA filaments are created equal: an experimental investigation

Purpose Additive manufacturing (AM) methods such as material extrusion (ME) are becoming widely used by engineers, designers and hobbyists alike for a wide variety of applications. Successfully manufacturing objects using ME three-dimensional printers can often require numerous iterations to attain predictable performance because the exact mechanical behavior of parts fabricated via additive processes are difficult to predict. One of that factors that contributes to this difficulty is the wide variety of ME feed stock materials currently available in the marketplace. These build materials are often sold based on their base polymer material such as acrylonitrile butadiene styrene or polylactic acid (PLA), but are produced by numerous different commercial suppliers in a wide variety of colors using typically undisclosed additive feed stocks and base polymer formulations. This paper aims to present the results from an experimental study concerned with quantifying how these sources of polymer variability can affect the mechanical behavior of three-dimensional printed objects. Specifically, the set of experiments conducted in this study focused on following: several different colors of PLA filament from a single commercial supplier to explore the effect of color additives and three filaments of the same color but produced by three different suppliers to account for potential variations in polymer formulation. Design/methodology/approach A set of five common mechanical and material characterization tests were performed on 11 commercially available PLA filaments in an effort to gain insight into the variations in mechanical response that stem from variances in filament manufacturer, feed stock polymer, additives and processing. Three black PLA filaments were purchased from three different commercial suppliers to consider the variations introduced by use of different feed stock polymers and filament processing by different manufacturers. An additional eight PLA filaments in varying colors were purchased from one of the three suppliers to focus on how color additives lead to property variations. Some tests were performed on unprocessed filament samples, while others were performed on objects three-dimensional printed from the various filaments. This study looked specifically at four mechanical properties (Young’s modulus, storage modulus, yield strength and toughness) as a function of numerous material properties (e.g. additive loading, molecular weight, molecular weight dispersity, enthalpy of melting and crystallinity). Findings For the 11 filaments tested the following mean values and standard deviations were observed for the material properties considered: pa = 1.3 ± 0.9% (percent additives), Mw = 98.6 ± 16.4 kDa (molecular weight), Ð = 1.33 ± 0.1 (molecular weight dispersity), Hm = 37.4 ± 7.2 J/g (enthalpy of melting) and = 19.6 ± 2.1% (crystallinity). The corresponding mean values and standard deviations for the resulting mechanical behaviors were: E = 2,790 ± 145 MPa (Young’s modulus), E’ = 1,050 ± 125 MPa (storage modulus), Sy = 49.6 ± 4.93 MPa (yield strength) and Ut = 1.87 ± 0.354 MJ/m^3 (toughness). These variations were observed in filaments that were all manufactured from the same base polymer (e.g. PLA) and are only different in terms of the additives used by the manufacturers to produce different colors or different three-dimensional printing performance. Unfortunately, while the observed variations were significant, no definitive strong correlations were found between these observed variations in the mechanical behavior of the filaments studied and the considered material properties. Research limitations/implications These variations in mechanical behavior and material properties could not be ascribed to any specific factor, but rather show that the mechanical of three-dimensional printed parts are potentially affected by variations in base polymer properties, additive usage and filament processing choices in complex ways that can be difficult to predict. Practical implications These results emphasize the need to take processing and thereby even filament color, into account when using ME printers, they emphasize the need for designers to use AM with caution when the mechanical behavior of a printed part is critical and they highlight the need for continued research in this important area. While all filaments used were marked as PLA, the feedstock materials, additives and processing conditions created significant differences in the mechanical behavior of the printed objects evaluated, but these differences could not be accurately and reliably predicted as function of the observed material properties that were the focus of this study. Originality/value The testing methods used in the study can be used by engineers and creators alike to better analyze the material properties of their filament printed objects, to increase success in print and mechanical design. Furthermore, the results clearly show that as AM continues to evolve and grow as a manufacturing method, standardization of feedstock processing conditions and additives would enable more reliable and repeatable printed objects and would better assist designers in effectively implementing AM methods.

Thermodynamic properties of methyl 4-(4-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate in organic solutions

The enthalpy and the entropy of dissolution of methyl 4-(4-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate in 2-propanol, ethyl acetate, acetonitrile, 2-propanone and benzene were determined from the temperature dependence of its solubility.The enthalpies and the entropies of mixing at 298 K were calculated taking into account the enthalpy of melting of the compound, determined via differential thermal analysis.The influence of the solvent on the solubility of the compound and on the corresponding enthalpy and entropy of mixing values was shown.

ESTABLISHMENT OF REGULARITY OF CHANGES IN CHEMICAL CHARACTERISTICS OF INTERMETALLIDES OF ALUMINUM SYSTEMS - LANTANIDES OF COMPOUNDS Al11Ln3, β-Al11Ln3 AND Al3Ln

Ensuring the effective development of industries based on natural resources, taking into account the necessary qualitative scientific justification, balancing the reasonable level of scientific and technological progress, is justified by the creation of new materials with specified characteristics. For this, fundamental studies of the physico-chemical and thermodynamic properties of various systems, in particular intermetallides (MI), are an important applied problem. At present, the study of aluminum-based metal systems involving rare-earth metals becomes especially urgent. The problem of determining the regularities of the changes in the thermochemical characteristics of the IM aluminum-lanthanide systems of the α-Al11Ln3, β- Al11Ln3 and Al3Ln compositions is considered, by refining the values of the temperature and melting enthalpy using semiempirical and calculated methods that allow obtaining fairly complete characteristics on the temperature and enthalpy of melting of the IM compositions of the rich aluminum with a demand in modern technology.

The Thermal Processes within Polyethylene in Mixtures with a High Content of Inorganic Components after Plastic Deformation under High Pressure

Mixtures of polyethylene and 80% germanium dioxide, magnesium, magnesium oxide, and sodium chloride were subjected to plastic deformation under a pressure of 0.5–4.0 GPa, and were then investigated by differential scanning calorimetry. The enthalpy of melting of the polymer in certain mixtures reached 300 J/g. On thermograms of deformed mixtures, exothermic processes were observed. The observed thermal effects are possibly due to interphase interaction at the phase boundary.