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The timber industry takes an important place in our modern life, and there has been an increased interest in it for a long time, especially in industrially developed countries. The concerns of the environmental organization regarding the plant wealth preservation have caused scientific trends to search for sources or industries that can achieve acceptable alternatives to natural wood. The materials in this article are related to industrial timber manufacturing of greenhouse wood waste, low density polyethylene and non-standard joinery waste. Moreover, panel samples made from the above materials were briefly subjected to tests as well as tested by fresh and salt water absorption.The density calculation results for all samples have shown the possibility of obtaining a wide range of wooden planks from the lightest to the heaviest ones, depending on the type of filler used. Additionally, the conducted research has shown the possibility of producing artificial wood panels made from the studied materials with good quality and fully satisfactory physical and mechanical properties.

Every day, the need for composite materials grows. The physical and chemical characteristics of the constituent materials inside the hybrid composite impact the final structure. The rate at which these individual properties are sustained varies, but it has an impact on the final properties of hybrid composites. Sporting goods and lightweight orthopaedic components are made from hybrid composites. Glass fibre epoxy and sawdust are utilised to construct hybrid composites in this study, using glass fibre to epoxy resin ratios of (60:40, 60:39, 60:38, 60:37).The current research involves the creation of hybrid composites and their study for flexural and tensile strength under various load conditions. Applying resin and hardener, as well as inserting reinforcement, is repeated in the hand-layup manufacturing process to improve characteristics and create a laminate form. They improve fatigue and fracture resistance while providing dimensional stability and weight savings.

The purpose of the present research was to assess the effect of three different fresh detox juices on the color stability of the resin composite with three different adhesive systems. Disc-shaped resin composite specimens were prepared. Composite discs were randomly divided into 3 subgroups according to the adhesive system (Adper EasyOne, BondForce, Clearfil QuickBond), adhesive system was applied to the upper surfaces of the composite discs according to the manufacturer`s instructions. The first color measurements were made with a spectrophotometer after the composite discs were kept in water for 24 hours. Samples in each group were divided into 4 subgroups according to the immersion solution (n=10; brands, water). The samples, which were kept in respective detox juices, were kept for 10 minutes twice a day, at other times they were kept in distilled water. Second color measurements were performed 30 days later. Data were analyzed with two-way ANOVA and Tukey HSD tests. According to the two-way analysis of variance, the adhesive system does not affect the color change significantly (p=0.773), but the detox juices has a significant effect on the color change (p=0.01). Fresh detox juices may adversely affect the color stability of adhesive systems, regardless of their color, but this effect may not be expected to be clinically observable.

Research on crack propagation for fiber reinforced composites containing flame retardant is rare. The micro-cracks propagation is a reason for delamination and debonding failure of fiber reinforced composites. To study the crack propagation of continuous glass fiber reinforced epoxy resin laminates that contained ammonium polyphosphate flame retardant (GFRP-APP), the quasi-static single-edge tensile loading (SETL) experiments for the end-notched GFRP-APP specimens were carried out by MTS universal electronic testing machine. The crack propagation of the end-notched 90° GFRP-APP specimen includes two types, both of which belong to opening type (mode I). Namely, one type is mode I multi-cracks propagation without preexisting crack, and the other is mode I fiber bridge propagation with preexisting crack. The intralaminar fracture toughness along fiber direction of GFRP-APP is approximately 8.4 N/mm, which is calculated by area method. The opening displacement-tensile force curves can be divided into three stages for 90° GFRP-APP specimen without crack, i.e., crack gestation, crack birth and crack propagation. However, the 90° GFRP-APP specimen with crack not contains the crack birth stage. Additionally, the microscopic morphology for the fracture face of pure epoxy resin and GFRP-APP, and the phase analysis for GFRP-APP were performed by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). As a conclusion, the pores and interfaces in materials were the guiding factors of micro-crack propagation, and the ammonium polyphosphate flame retardant particle contributed extra interfaces.

At the moment, the tendency in the composites field, is to use natural resins and fibers to obtain „environmental friendly” materials, that are compostable and biodegradable. In this paper there is an experimental study of the depletion capacity of the vibration from the composite beams, using the hardener made of cotton, flax, hemp, silk textile and the three types of the Dammar hybrid resin matrix. The damping factor and the eigenfrequency of the vibrations was determined experimentally for these bars. Based on the acquired results, the dynamic elasticity modulus and the loss factor were calculated, for each composite material studied.

Highlighting the properties of polymer composites is a complex process given their great diversity and the wide range in which their characteristics could vary. An Artificial Neural Network model for predicting tensile strength was designed using LabVIEW software. The proposed model was developed for randomly reinforced polymeric composite materials with 30%, 40% and 50% fiber-glass. Volume fraction of glass fibre has represented the independent variable for this study. The dependence of the tensile strength on the volume fraction was investigated and highlighted by modelling using neural networks. The designed Artificial Neural Network behaves as a computational system that process data input into a desired output using a network of functions composed of layers. The training process was developed with different Artificial Neural Network architectures with two hidden layers to produce the best prediction results. For each hidden layer the number of neurons was varied be-tween 3 to 50.

The present paper analyses the possibility of using the digital image correlation technique to study the mechanical behavior of small scale components. A microscope is supplemented to the equipment for magnification, together with a miniature tensile testing machine. Several samples with already studied stress concentrators were analyzed. For comparison purposes, a finite element model of the geometry, with appropriate loading conditions, is created and the strain field is compared, in orderv to be validated to the experimental one. Results show that an accurate reading can be made by using this technique. Furthermore, crack initiation and its propagation path can be determined, by the appearance of high strains in the region.

The search for green composite for sound-absorbing material has increased a significant interest. In this study, polystyrene (PS) composite foam filled with primary sludge and boiler ash from pulp mill was produced. The product was characterized using analytical techniques such as FTIR, XRD, SEM, TGA, and DSC, while the mechanical properties and sound-absorbing coefficient were analyzed regarding ASTM D 2240 and ASTM E-1050-98, respectively. The results showed that the sludge has 1β crystalline polymorph cellulose from the pulp. The chemical reaction can be seen by the chemical bond formed during the mixing process. The peak expansion occurred at 1600.44 cm-1 indicating the presence of a C=C functional group of maleic anhydride with polymer and filler. SEM images showed that the filler was distributed and dispersed into the polymer matrix and no agglomeration was produced. The sound-absorbing composites had complied ISO 11654:1997 regarding the sound absorption coefficient rating level on materials for rooms with sound absorption classes D and C with the value of α 0.328-0.793.

This study was geared to analyze the preparation methods of pullulan acetate-based nanoparticles loaded with 5-fluorouracil, as well as the potential of pullulan as a biopolymer matrix for obtaining nanoparticles applied in the delivery of anticancer drugs (5-FU). Various methods were used to produce pullulan acetate-based nanoparticles loaded with 5-FU, including nanoprecipitation, modified nanoprecipitation, and double emulsion. Pullulan was previously chemically modified with acetic anhydride, dimethylformamide and pyridine, and yielded pullulan acetate. Pullulan was made using the Aureobasidium pullulans strain through a fermentation procedure. UV-Vis Spectro-photometric and dynamic light scattering (DLS) methods were used to assess entrapment effectiveness, size, and polydispersity index (PDI) of pullulan acetate-based nanoparticles loaded with 5-FU. Based on the properties of the nanoparticles obtained, the optimum preparation method was chosen. The maximum entrapment efficiency was found in pullulan acetate nanoparticles loaded with 5-FU generated by a double emulsion method. The mean hydrodynamic size and PDI of all nanoparticles were adequate. The best formulation showed faster 5-FU release profile in acid phosphate-buffered saline (pH 5) than in phosphate-buffered saline pH 7.4. According to the findings, pullulan derivatives have a great potential for producing nanoparticles that might be used to deliver anticancer medicines.

Intended to draw a frame of the impact of plastics usage and the role of the circular economy, this paper relied on specific literature, data from different studies, case studies, reports and databases existing on the research area. Being produced at low costs and used in a wide range of fields, plastics has been confirmed as one of the most impactful inventions for human. Recently, during the pandemic years, plastics has gotten multiple usages, such as keeping a hygienic sanitary environment facing the critical situations, with a highly increased role in the fight against the SARS-COVID-19 crisis. It is also well known that plastics presents risks arising from its production flow, linked to a huge degree of massive pollution with high impact on the environment. Plastic waste exposed to the environment generated problems and it is of huge concern for all forms of life. As plastics products are present all around the world, there is an increasing statement to one-use plastics in the environment. Thus, it is urge to take actions for managing this situation as appropriate, to protect the environment and reduce the consumption of plastics, which can be achieved by developing and sustain the circular economy, as a new research field to explore. Through this paper we intended to emphasize the importance that, both theoretical contribution and practical measures, have on the production, the use and recycling of plastics and on the circular economy.