Poly(lactic acid) green composites filled with linseed cake as an agricultural waste filler. Influence of oil content within the filler on the rheological behavior

Ecologically Modified Leather of Bacterial Origin

The research presented here is an attempt to develop an innovative and environmentally friendly material based on bacterial nanocellulose (BNC), which will be able to replace both animal skins and synthetic polymer products. Bacterial nanocellulose becomes stiff and brittle when dried, so attempts have been made to plasticise this material so that BNC can be used in industry. The research presented here focuses on the ecological modification of bacterial nanocellulose with vegetable oils such as rapeseed oil, linseed oil, and grape seed oil. The effect of compatibilisers of a natural origin on the plasticisation process of BNC, such as chlorophyll, curcumin, and L-glutamine, was also evaluated. BNC samples were modified with rapeseed, linseed, and grapeseed oils, as well as mixtures of each of these oils with the previously mentioned additives. The modification was carried out by passing the oil, or oil mixture, through the BNC using vacuum filtration, where the BNC acted as a filter. The following tests were performed to determine the effect of the modification on the BNC: FTIR spectroscopic analysis, contact angle measurements, and static mechanical analysis. As a result of the modification, the BNC was plasticised. Rapeseed oil proved to be the best for this purpose, with the help of which a material with good strength and elasticity was obtained.

Technological limitations in obtaining and using cellulose biocomposites

Among the many possible types of polymer composite materials, the most important are nanocomposites and biocomposites, which have received tremendous attention in recent years due to their unique properties. The fundamental benefits of using biocomposites as alternative materials to “petroleum-based” products are certainly shaping current development trends and setting directions for future research and applications of polymer composites. A dynamic growth of the production and sale of biocomposites is observed in the global market, which results not only from the growing interest and demand for this type of materials, but also due to the fact that for the developed and modified, thus improved materials, the area of their application is constantly expanding. Already today, polymer composites with plant raw materials are used in various sectors of the economy. In particular, this concerns the automotive and construction industries, as well as widely understood packaging. Bacterial cellulose, for example, also known as bionanocellulose, as a natural polymer with specific and unique properties, has been used extensively,primarily in numerous medical applications. Intensive research is also being carried out into composites with natural fibres composed mainly of organic compounds such as cellulose, hemicellulose and lignin. However, three aspects seem to be associated with the popularisation of biopolymers: performance, processing and cost. This article provides a brief overview of the topic under discussion. What can be the technological limitations considering the methods of obtaining polymer composites with the use of plant filler and the influence on their properties? What properties of cellulose constitute an important issue from the point of view of its applicability in polymers, in the context of compatibility with the polymer matrix and processability? What can be the ways of changing these properties through modifications, which may be crucial from the point of view of the development directions of biopolymers and bioplastics, whose further new applications will be related, among others, to the enhancement of properties? There still seems to be considerable potential to improve the cellulose material composites being produced, as well as to improve the efficiency of their manufacturing. Nevertheless, the material still needs to be well optimized before it can replace conventional materials at the industrial level in the near future. Typically, various studies discuss their comparison in terms of production, properties and highly demanding applications of plant or bacterial nanocellulose. Usually, aspects of each are described separately in the literature. In the present review, several important data are gathered in one place, providing a basis for comparing the types of cellulose described. On the one hand, this comparison aims to demonstrate the advantage of bacterial cellulose over plant cellulose, due to environmental protection and its unique properties. On the other hand, it aims to prepare a more comprehensive point of view that can objectively help in deciding which cellulosic raw material may be more suitable for a particular purpose, bacterial cellulose or plant cellulose.

Recent Advances in Development of Waste-Based Polymer Materials: A Review

Limited petroleum sources, suitable law regulations, and higher awareness within society has caused sustainable development of manufacturing and recycling of polymer blends and composites to be gaining increasing attention. This work aims to report recent advances in the manufacturing of environmentally friendly and low-cost polymer materials based on post-production and post-consumer wastes. Sustainable development of three groups of materials: wood polymer composites, polyurethane foams, and rubber recycling products were comprehensively described. Special attention was focused on examples of industrially applicable technologies developed in Poland over the last five years. Moreover, current trends and limitations in the future “green” development of waste-based polymer materials were also discussed.

Impact Strength of Hybrid Epoxy–Basalt Composites Modified with Mineral and Natural Fillers

The aim of this study was to evaluate the influence of mineral and natural additives (2.5; 5; 10 wt.%) on the impact strength of epoxy–basalt composites. Three types of filler were used to modify the epoxy matrix: basalt powder (BP), basalt microfiber (BF) and sunflower husk ash (SA). The impact strength and the maximum force were determined for the materials. The results of the conducted research confirm that the addition of a powder fillers to the epoxy matrix of basalt fiber reinforced composites is an effective method of improving their impact characteristic. The introduction of fillers to epoxy resin allowed to improve the impact properties of all tested groups of laminates. Moreover, in all cases, the introduction of the filler increased the maximum force needed to damage the composite sample and their hardness. For the modified materials, an increase in impact strength was recorded, respectively: by 44% for composites with BP, by 7.5% for composites with BF and by 2.5% for composites with SA.

Casein/Apricot Filler in the Production of Flame-Retardant Polyurethane Composites

Polyurethane (PUR) composites reinforced with 1, 2, and 5 wt.% of apricot filler modified with casein were synthesized in the following study. The impact of 1, 2, and 5 wt.% of casein/apricot filler on the cellular structure and physico-mechanical performances of reinforced PUR composites were determined. It was found that the incorporation of 1 and 2 wt.% of casein/apricot filler resulted in the production of PUR composites with improved selected physical, thermal, and mechanical properties, while the addition of 5 wt.% of casein/apricot filler led to some deterioration of their physico-mechanical performance. The best results were obtained for PUR composites reinforced with 2 wt.% of casein/apricot filler. Those composites were characterized by a uniform structure and a high content of closed cells. Compared with the reference foam, the incorporation of 2 wt.% of casein/apricot filler resulted in improvement in compressive strength, flexural strength, impact strength, and dynamic mechanical properties-such as glass transition temperature and storage modulus. Most importantly, PUR composites showed better fire resistance and thermal stability due to the good thermal performance of casein. The main aim of this article is to determine the influence of the natural combination of the apricot filler and casein on the mechanical properties and flammability of the obtained composites.

Cellulose Modification for Improved Compatibility with the Polymer Matrix: Mechanical Characterization of the Composite Material

The following article is the presentation attempt of cellulose hybrid chemical modification approach as a useful tool in improving the mechanical properties of plant fiber-filled polymer materials. The treatment process is a prolonged method of the cellulose maleinization and consists of two steps: 1. solvent exchange (altering fiber structure); 2. maleic anhydride (MA) chemical grafting (surface modification). Thanks to the incorporated treatment method, the created ethylene-norbornene copolymer composite specimen exhibited an improved performance, tensile strength at the level of (38.8 ± 0.8) MPa and (510 ± 20)% elongation at break, which is higher than for neat polymer matrix and could not be achieved in the case of regular MA treatment. Moreover, both the Payne effect and filler efficiency factor indicate a possibility of the fiber reinforcing nature that is not a common result. Additionally, the polymer matrix employed in this research is widely known for its excellent resistance to aqueous and polar organic media, good biocompatibility, and the ability to reproduce fine structures which makes it an interesting material regarding healthcare applications. Therefore, plant fiber-based polymer materials described in this research might be potentially applied in this area, e.g., medical devices, drug delivery, wearables, pharmaceutical blisters, and trays.

Crystallization of polylactide-based green composites filled with oil-rich waste fillers

Polylactide is a highly demanded biopolymer, whose industrial application constantly increases. Its disadvantages such as brittleness and slow crystallization rate can be overcome by application of different additives. Because of environmental issues, using natural waste fillers as modifying agents for polylactide is especially interesting. In this study linseed cake, a byproduct of oil extraction from linseed, characterized by oil content of 0.9–39.8 wt.%, was added to polylactide to influence its crystallization behavior. The formation of the crystalline phase was studied by differential scanning calorimetry in isothermal and non-isothermal conditions and analyzed according to methods by Jeziorny, Ozawa, Mo and Avrami. The samples’ microstructures were observed using polarized light microscopy. The crystallization rate and Avrami exponent of samples crystallized in different conditions were evaluated. It was found that addition of 10 wt.% of linseed cake containing at least 17.7 wt.% oil notably changes the crystallization of polylactide, increasing its crystallinity and promoting the growth of crystallites.

Poly(l-Lactic Acid)/Pine Wood Bio-Based Composites

Bio-based composites made of poly(l-lactic acid) (PLLA) and pine wood were prepared by melt extrusion. The composites were compatibilized by impregnation of wood with γ-aminopropyltriethoxysilane (APE). Comparison with non-compatibilized formulation revealed that APE is an efficient compatibilizer for PLLA/wood composites. Pine wood particles dispersed within PLLA act as nucleating agents able to start the growth of PLLA crystals, resulting in a faster crystallization rate and increased crystal fraction. Moreover, the composites have a slightly lower thermal stability compared to PLLA, proportional to filler content, due to the lower thermal stability of wood. Molecular dynamics was investigated using the solid-state ¹H NMR technique, which revealed restrictions in the mobility of polymer chains upon the addition of wood, as well as enhanced interfacial adhesion between the filler and matrix in the composites compatibilized with APE. The enhanced interfacial adhesion in silane-treated composites was also proved by scanning electron microscopy and resulted in slightly improved deformability and impact resistance of the composites.

Drying of the Natural Fibers as A Solvent-Free Way to Improve the Cellulose-Filled Polymer Composite Performance

When considering cellulose (UFC100) modification, most of the processes employ various solvents in the role of the reaction environment. The following article addresses a solvent-free method, thermal drying, which causes a moisture content decrease in cellulose fibers. Herein, the moisture content in UFC100 was analyzed with spectroscopic methods, thermogravimetric analysis, and differential scanning calorimetry. During water desorption, a moisture content drop from approximately 6% to 1% was evidenced. Moreover, drying may bring about a specific variation in cellulose's chemical structure. These changes affected the cellulose-filled polymer composite's properties, e.g., an increase in tensile strength from 17 MPa for the not-dried UFC100 to approximately 30 MPa (dried cellulose; 24 h, 100 °C) was observed. Furthermore, the obtained tensile test results were in good correspondence with Payne effect values, which changed from 0.82 MPa (not-dried UFC100) to 1.21 MPa (dried fibers). This raise proves the reinforcing nature of dried UFC100, as the Payne effect is dependent on the filler structure's development within a polymer matrix. This finding paves new opportunities for natural fiber applications in polymer composites by enabling a solvent-free and efficient cellulose modification approach that fulfils the sustainable development rules.

Assessment of Photodegradation and Biodegradation of RPU/PIR Foams Modified by Natural Compounds of Plant Origin

Four types of rigid polyurethane-polyisocyanurate foams (RPU/PIR) were obtained. Three of them were modified by powder fillers, such as cinnamon extract (C10 foam), green coffe extract (KZ10), and cocoa extract (EK10) in an amount of 10 wt %. The last foam was obtained without a filler (W foam). The basic properties and thermal properties of obtained foams were examined. All foams were subjected to degradation in the climatic chamber acting on samples of foams in a defined temperature, humidity, and UV radiation for 7, 14, and 21 days. The physico-mechanical properties of foams were tested. The compressive strength of degraded foams after 7, 14, and 21 days was compared with the compressive strength of nondegraded foams (0 days). The chosen properties of degraded foams, such as cellular structure by scanning electron microscopy (SEM) and changes of chemical structure by FTIR spectroscopy were compared. The obtained foams were also subjected to degradation in a circulating air dryer in an increased temperature (120 °C) for 48 h. Additionally, W, C10, ZK10, EK10 foams were placed in a soil environment and subjected to 28 days biodegradation process. The biochemical oxygen demand (BOD), the theoretical oxygen demand (TOD), and the degree of biodegradation (Dt) of foams were determined in this measurment. Test results showed that the compressive strength of foams decreased with the longer time of foam degradation in the conditioner. The foam subjected to degradation darkened and became more red and yellow in color. The addition of natural compounds of plant origin to foams increased their susceptibility to biodegradation.

Accelerated Weathering of Polylactide-Based Composites Filled with Linseed Cake: The Influence of Time and Oil Content within the Filler

This paper presents the effects of accelerated weathering on the properties of polylactide (PLA) composites filled with linseed cake. The particle-shaped waste filler with different linseed oil content (0.9–39.8 wt %) was incorporated with constant amount of 10 wt % to a polymeric matrix and subjected to accelerated weathering tests with different exposition times. The structure of the composites, their mechanical, thermal, and thermo-mechanical properties were evaluated by means of scanning electron microscopy, tensile test, dynamic mechanical thermal analysis, and differential scanning calorimetry prior to and after weathering. The results of the measurements were analyzed in reference to the amount of crude oil contained in the filler. The behavior of the multiphase composite during weathering was described. It was found that the oil-rich samples during the first stage of the process showed increased resistance to hydrolytic degradation due to their relatively high crystallinity. The presence of water and elevated temperatures caused swelling of the filler and cracking of the polymeric matrix. Those discontinuities enabled the plasticizing oil to be rinsed out of the composite and thus water penetrated into the samples. As a result, the PLA-based composites containing oil-rich linseed cake were found to be more vulnerable to hydrolytic degradation in a longer time.