RESUMEN
This paper presents the results of a study investigating the biodegradation of poly(butylene succinate) (PBS)/wheat bran (WB) biocomposites. Injection mouldings were subjected to biodegradation in compost-filled bioreactors under controlled humidity and temperature conditions. The effects of composting time (14, 42 and 70 days) and WB mass content (10%, 30% and 50% wt.) on the structural and thermal properties of the samples were investigated. Measurements were made by infrared spectral analysis, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and gel permeation chromatography. Results demonstrated that both the thermal and structural properties of the samples depended greatly on the biodegradation time. Specifically, their crystallinity degree increased significantly while molecular mass sharply decreased with biodegradation time, whereas their thermal resistance only showed a slight increase. This resulted from enzymatic hydrolysis that led to the breakdown of ester bonds in polymer chains. It was also found that a higher WB content led to a higher mass loss in the biocomposite samples during biodegradation and affected their post-biodegradation properties. A higher bran content increased the degree of crystallinity of the biocomposite samples but reduced their thermal resistance and molecular mass.
RESUMEN
The utilization of plant based fillers: onion peels (OP) and durum wheat bran (WB) to obtain sustainable biocomposite materials with poly(butylene succinate) (PBS) is presented in this paper. The biocomposites were first obtained in pellet form by extrusion method and then injection moldings were made from the pellets. Two kinds of biocomposites were fabricated containing 15% and 30% wt. of OP or WB. Additionally, pure PBS moldings were prepared for comparative purposes. The effect of the filler type and its amount on the chemical structure, density, thermal, and thermo-mechanical properties of the fabricated composite samples was studied. Fourier-transform infrared spectroscopy results showed that the composite preparation method had no effect on the chemical structure of composite components, but weak interactions such as hydrogen bonding between OP or WB and PBS was observed. The addition of OP or WB to the composite with PBS reduced its thermal stability in comparison with pure PBS, all studied composites start to degrade below 290 °C. Additionally, the mechanical properties of the composites are worse than PBS, as the impact strength dropped by about 70%. The deterioration of tensile strength was in the range 20-47%, and the elongation at maximum load of the composites was in the range 9.22-3.42%, whereas for pure PBS it was 16.75%. On the other hand, the crystallinity degree increased from 63% for pure PBS to 79% for composite with 30% wt. of WB. The Young's modulus increased to 160% for composition with 30% wt. of OP. Additionally, the hardness of the composites was slightly higher than PBS and was in the range 38.2-48.7 MPa. Despite the reduction in thermal stability and some mechanical properties, the studied composites show promise for everyday object production.
RESUMEN
The article presents the results of flammability tests on polymer compositions with wheat bran (WB) as the applied filler, and polyethylene (PE) or poly(butylene succinate) (PBS) as the matrix material. Tests were conducted using samples of compositions containing 10, 30 and 50%wt wheat bran. The test samples were manufactured by injection moulding from compositions previously produced by extrusion pelleting. For comparative purposes, samples made only of the plastics used for the composition matrix were also examined. Flammability tests were carried out in accordance with the recommendations of EN 60695-11-10 Part 11-10 with horizontal and vertical positioning of the sample, using a universal flammability-test-stand. During the flammability tests, changes in the temperature field in the area of the burning sample were also recorded, using a thermal imaging camera. Sample residues after flammability tests were also examined with infrared spectroscopy (FTIR) to assess their thermal destruction. The results of the study showed a significant increase in flammability with bran content for both PE and PBS matrix compositions. Clear differences were also found in the combustion behaviour of the matrix materials alone. Both the burning rate and maximum flame temperature were lower in favour of PBS. PBS compositions with wheat bran also showed lower flammability, compared with their PE matrix counterparts.
RESUMEN
This paper presents the assumptions of a thermodynamic equation of state for polymers according to the Renner model. The experiments involved extruding a biocomposite based on poly(butylene succinate) that was filled with ground wheat bran with its size not exceeding 200 µm. The biocomposite was produced in pellet form with three different contents by weight of wheat bran, i.e., 10%, 30% and 50%. All specimens were examined for their thermodynamic p-v-T characteristics. Taking advantage of the SimFit module of Cadmould 3D-F, experimental results were used to determine the coefficients of thermodynamic equation of state for the tested biocomposite according to the Renner model. The coefficients were then used to calculate transition temperature and to create diagrams illustrating the relationship between pressure, temperature and specific volume for the tested biocomposite. The obtained results can serve as a basis for assessing the suitability of the biocomposite for injection molding, selecting technological parameters of this process, as well as for analyzing shrinkage and defects of injection-molded parts.
RESUMEN
Unmodified poly (butylene succinate) (PBS) is characterized by very good processability; however, after the incorporation of various fillers of plant origin, its processing becomes much more complicated and its properties are significantly affected. Detailed studies of the processing aspects of PBS/wheat bran (WB) biocomposition are lacking, despite the addition of WB having a significant impact on both the production efficiency and the properties of end products. This research paper presents test results of the co-rotating twin-screw extrusion processing of a biodegradable polymer blend, the matrix of which was PBS, with WB as the filler. In undertaking this task, we examined the impact of extruder screw rotational speed and WB content on the characteristics of extrusion processing, as well as on certain thermal, physical, structural and processing properties of the obtained blend. The WB introduced to the blend was in the form of a selected fraction with particles smaller than 0.2 mm. The measurements were conducted using the Design of Experiment (DOE) methods, which enabled establishing the studied relationships in the form of polynomials and response surfaces. The determined extrusion process characteristics covered the impact of screw rotational speed and WB content on the mass flow rate of the processed blend and its pressure, the screw drive torque and specific energy consumption. The studies of the obtained polymer blend included determining the impact of the aforementioned variable factors on the melt flow rate (MFR) index, chemical structure (FTIR), thermal properties (differential scanning calorimetry (DSC), thermogravimetry (TG), derivative thermogravimetry (DTG)), p-v-T relationships, microstructure, density and moisture absorbance. Analysis of variance (ANOVA) was used to assess the effect of individual variable factors. The results of this work are presented, inter alia, using Pareto charts of standardized effects, which illustrate the influence of individual terms of the determined regression equations on the studied quantity.
RESUMEN
The results of comprehensive studies on accelerated (artificial) ageing and biodegradation of polymer biocomposites on PBS matrix filled with raw wheat bran (WB) are presented in this paper. These polymer biocomposites are intended for the manufacture of goods, in particular disposable packaging and disposable utensils, which decompose naturally under the influence of biological agents. The effects of wheat bran content within the range of 10-50 wt.% and extruder screw speed of 50-200 min-1 during the production of biocomposite pellets on the resistance of the products to physical, chemical, and biological factors were evaluated. The research included the determination of the effect of artificial ageing on the changes of structural and thermal properties by infrared spectra (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). They showed structural changes-disruption of chains within the ester bond, which occurred in the composition with 50% bran content as early as after 250 h of accelerated ageing. An increase in the degree of crystallinity with ageing was also found to be as high as 48% in the composition with 10% bran content. The temperature taken at the beginning of weight loss of the compositions studied was also lowered, even by 30 °C at the highest bran content. The changes of mechanical properties of biocomposite samples were also investigated. These include: hardness, surface roughness, transverse shrinkage, weight loss, and optical properties: colour and gloss. The ageing hardness of the biocomposite increased by up to 12%, and the surface roughness (Ra) increased by as much as 2.4 µm at the highest bran content. It was also found that ageing causes significant colour changes of the biocomposition (ΔE = 7.8 already at 10% bran content), and that the ageing-induced weight loss of the biocomposition of 0.31-0.59% is lower than that of the samples produced from PBS alone (1.06%). On the other hand, the transverse shrinkage of moldings as a result of ageing turned out to be relatively small, at 0.05%-0.35%. The chemical resistance of biocomposites to NaOH and HCl as well as absorption of polar and non-polar liquids (oil and water) were also determined. Biodegradation studies were carried out under controlled conditions in compost and weight loss of the tested compositions was determined. The weight of samples made from PBS alone after 70 days of composting decreased only by 4.5%, while the biocomposition with 10% bran content decreased by 15.1%, and with 50% bran, by as much as 68.3%. The measurements carried out showed a significant influence of the content of the applied lignocellulosic fillers (LCF) in the form of raw wheat bran (WB) on the examined properties of the biocompositions and the course of their artificial ageing and biodegradation. Within the range under study, the screw speed of the extruder during the production of biocomposite pellets did not show any significant influence on most of the studied properties of the injection mouldings produced from it.
RESUMEN
The paper presents a procedure of the manufacturing and complex analysis of the properties of injection mouldings made of polymeric composites based on the poly(butylene succinate) (PBS) matrix with the addition of a natural filler in the form of wheat bran (WB). The scope of the research included measurements of processing shrinkage and density, analysis of the chemical structure, measurements of the thermal and thermo-mechanical properties (Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TG), Heat Deflection Temperature (HDT), and Vicat Softening Temperature (VST)), and measurements of the mechanical properties (hardness, impact strength, and static tensile test). The measurements were performed using design of experiment (DOE) methods, which made it possible to determine the investigated relationships in the form of polynomials and response surfaces. The mass content of the filler and the extruder screw speed during the production of the biocomposite granulate, which was used for the injection moulding of the test samples, constituted the variable factors adopted in the DOE. The study showed significant differences in the processing, thermal, and mechanical properties studied for individual systems of the DOE.
RESUMEN
The study investigates the effect of the content and size of wheat bran grains on selected properties of a lignocellulosic biocomposite on a polyethylene matrix. The biocomposite samples were made by injection method of low-density polyethylene with 5%, 10% and 15% by weight of wheat bran. Three bran fractions with grain sizes <0.4 mm, 0.4-0.6 mm and 0.6-0.8 mm were used. The properties of the mouldings (after primary shrinkage) were examined after their 2.5-year natural aging period. Processing properties, such as MFR (mass flow rate) and processing shrinkage, were determined. Selected physical, mechanical and structural properties of the produced biocomposite samples were tested. The results allowed the determination of the influence of both the content of bran and the size of its grains on such properties of the biocomposite as: color, gloss, processing shrinkage, tensile strength, MFR mass flow rate, chemical structure (FTIR), thermal properties (DSC, TG), p-v-T relationship. The tests did not show any deterioration of the mechanical characteristics of the tested composites after natural aging.
RESUMEN
There are many methods widely applied in the engineering of biomaterials to improve the mechanical properties of the dental composites. The aim of this study was to assess the effect of modification of dental composites with liquid rubber on their mechanical properties, degree of conversion, viscosity, and cytotoxicity. Both flow and packable composite consisted of a mixture of Bis-GMA, TEGDMA, UDMA, and EBADMA resins reinforced with 60 and 78 wt.% ceramic filler, respectively. It was demonstrated that liquid rubber addition significantly increased the fracture toughness by 9% for flow type and 8% for condensable composite. The influence of liquid rubber on flexural strength was not statistically significant. The addition of the toughening agent significantly reduced Young's modulus by 7% and 9%, respectively, while increasing deformation at breakage. Scanning electron microscopy (SEM) observations allowed to determine the mechanisms of toughening the composites reinforced with ceramic particles. These mechanisms included bridging the crack edges, blocking the crack tip by particles and dissipation of fracture energy by deflection of the cracks on larger particles. The degree of conversion increased after modification, mainly due to a decrease in the matrix resin viscosity. It was also shown that all dental materials were nontoxic according to ISO 10993-5, indicating that modified materials have great potential for commercialization and clinical applications.
RESUMEN
The study investigated the impact of the extruder screw design solution-the intensive mixing tip used-on the course of the extrusion process and the properties of the obtained biocomposite extrudate. A lignocellulosic wheat bran biocomposite based on a low-density polyethylene matrix was extruded. Three mixing tips of the screw were used interchangeably: apineapple tip, a cut rings tip, and a Maddock tip. The experimental tests carried out included the production of an extrudate with a mass content of bran altered within the range from 10% to 50%. Processing properties such as the melt flow rate (MFR) and mass flow rate of the extruded biocomposite were determined. Selected physical, mechanical, and structural properties of the biocomposite extrudate obtained with the use of the three tested mixing tips at five bran contents were tested.
RESUMEN
The aim of the study was to determine the effect of the application of processing screws with a modified test segment in a corotating twin-screw extruder on selected properties of talc-filled polypropylene extrudate. The test segment was built of trilobe kneading elements and its design modifications refered to changing the distance between the kneading elements and the angle of positions of kneading elements that are relative to each other. The performed tests included the production of extrudate with various degrees of talc-filling using five design solutions of the test segment and then measurements of selected properties, such as tensile strength, elongation at maximum tensile stress, and melt flow rate. Structural studies using scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were also carried out. The study includes not only the description of experimental results but also the determination of empirical models describing the dependence of the properties of the obtained extrudate on the conditions of the extrusion process and the design features of the test segment.