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From the desire to produce environmentally friendly composites, sandwich composites with a matrix made of a Dammar-based hybrid resin, a core of chopped corn cobs, and faces made of natural fabrics were cast and researched in terms of their mechanical properties. The low production cost and the mechanical characteristic values obtained for these sandwich composites have shown that they represent an alternative to MDF, or PAL (Medium Density Fiberboard, or Chipboard). As an application, two elements of a bathroom cabinet were made. The cabinet was exposed to a high-humidity environment, and it was found that the humidity level did not cause any changes in shape or appearance of the elements made from the sandwich composite. [ABSTRACT FROM AUTHOR]

As the amount of agricultural waste produced annually worldwide is very high, numerous studies have been conducted with the aim of using them in the structure of composite materials that have a minimal impact on the environment, reduced costs, and can be used in various fields of activity. In this research, four types of composite materials were cast, with a reinforcement of chopped corn cobs and with a matrix of acrylic resin, respectively, of three hybrid resins having various mass proportions, where Dammar natural resin prevailed. The chemical structure of the composites with hybrid matrix was determined using molecular spectroscopic microanalysis, and some mechanical properties of all the composites were investigated. It was found that the values of the obtained mechanical characteristics were limited. [ABSTRACT FROM AUTHOR]

This study presents an analysis of mechanical properties derived from tensile tests conducted on three sets of test specimens composed of a bioresin blend. The bioresin formulation consisted of Dammar at volumetric ratios of 50%, 60%, and 70%, combined with epoxy resin and its associated strengthener to facilitate rapid polymerization. The primary focus was to investigate the impact of varying epoxy resin proportions on the mechanical behaviour of the bioresin. In the subsequent part of the research, we determined characteristic curves, tensile strength, elasticity modulus, and elongation at the point of fracture for composite materials. These composites featured the same bioresin matrix as investigated in the initial phase, with the addition of reinforcing agents such as cotton, linen, and hemp. [ABSTRACT FROM AUTHOR]

In this paper we build some composite materials reinforced with needles from fir trees. In order to build the samples, we have firstly created some strips in this way: we put the pines, continuously, on a sheet of paper where we apply a thin layer of resin (we have used epoxy and polyester ones). We have made 10 strips and we have glued them together by using the same synthetic resins (epoxy and polyester). In the end we have obtained some composites reinforced with strips from fir trees needles and paper sheet, and the matrix is made from epoxy and polyester resins. From the obtained plate, we have cut some samples in order to study their free vibrations. We have placed an accelerometer at about 10 mm from the free edge and we have clamped the samples on several free lengths. The accelerometer is connected to a signal conditioner NEXUS which is also connected to a data acquisition system SPIDER 8. The data acquisition system is connected to a notebook through USB port. From the samples free vibrations, we have determined: the eigenfrequency, the damping factor per unit mass, damping factor per unit length, dynamic stiffness, dynamic Young modulus and loss factor.

In this research some composite materials built in sandwich type style are studied. The lower and upper layers, that reinforce the samples, are made from poplar strips. The core is made from crushed corn cob and the adhesion of all parts (layers and core) is made by using hybrid resins based on a combination from dammar resin and the synthetic acrylic one (with its hardener). The static and dynamic mechanical behaviour by testing the samples to tensile and bending were studied. Two types of hybrid resins were used: one abbreviated as type B with the percentage of 60% dammar and 40% acrylic resin with hardener and one abbreviated as type C with the percentage of 65% dammar and 35% acrylic resin with hardener. A general conclusion from this study it was: the mechanical properties decrease with the dammar percentage increase. This fact can be explained by the decreased mechanical properties of the natural dammar resin compared to the synthetic acrylic one. [ABSTRACT FROM AUTHOR]

Using the experimental determinations obtained on the basis of compressive stress, some mechanical properties were studied for composite materials with the matrix of three types of resin, epoxy, unsaturated polyester and hybrid based on Dammar natural resin, which was reinforced with isophthalic resin granules NPG (Neopentyl Glycol) Chromat Kayan / Javari / Payette type. The stress-strain diagrams, compressive yield strength, compressive strength and modulus of elasticity in uniaxial compression were obtained. With the EDS analysis, the graphical distribution of the atomic spectra of the elements identified in the hybrid resin was determined and the image of the fracture surface of a hybrid resin specimen was presented based on the stereomicroscopic analysis (SEM). [ABSTRACT FROM AUTHOR]

Humanity's ability to find solutions to protect the environment will prove that we are an intelligent species. One solution would be to use only materials from very rapidly renewable resources to make equipment and consumer goods. The study in this article falls in the direction presented earlier. More specifically, the reinforced composite materials were made from ground sunflower seed husks (waste from the production process of oil factories) and have as a matrix a hybrid resin with 50%, 60%, 70% and 80% volumic proportion of Dammar natural resin. For this type of composite materials, the vibration behavior was studied according to the proportion of natural Dammar resin in the matrix used. The eigen frequency and damping factor for the first natural vibration mode were determined experimentally. [ABSTRACT FROM AUTHOR]

In this paper some mechanical characteristics of a composite made from a hybrid resin and reinforced with corn cob powder are presented. The hybrid resin was made with a combination between the natural dammar resin combined with a small percentage of acrylic one. The synthetic resin was inserted in order to increase the polymerization process which was produced in about 24 h. In the fist part of the investigation, from the compression test, some mechanical characteristics are determined, such as: breaking strength or maximum force obtained at breaking. Then, by using the SEM analysis and EDS spectrometry, some samples with 50% dammar and 60% dammar were investigated. The last hybrid resin test was Shore D hardness and it was found out that the hardness decreases with the increase of dammar percentage. In the last part of the study, some composites by using the poposed hybrid resin reinforced with corn cob powder were manufactured. It has been found out that the proposed composite reinforced with corn cob powder has increased compression mechanical properties compared other composites that have the same reinforcement. [ABSTRACT FROM AUTHOR]

The production of "environmentally friendly" composite materials involves the use of natural reinforcements and natural or hybrid resins. The first part of this paper describes how is obtained a hybrid resin from Dammar natural resin, polymerized with acrylic resin. For this hybrid resin were determined some mechanical properties, such as: Young's static modulus, breaking strength, elongation at break, water absorption, shore hardness and damping factor per unit mass together with its own frequency corresponding to the first proper mode of vibration. From the point of view of static mechanical properties, it is found that the new hybrid resin has lower properties compared to similar ones that are already studied. Notes a decrease of 2-3 units in the value of breaking strength and 600 units in the static Young's modulus. But the advantage of the proposed hybrid resin is the reduced curing time compared to similar ones. In the second part, based on the hybrid resin obtained and by reusing some waste from the agri-food industry, two new types of composite materials were molded. The first was reinforced with chicken feathers and sheets of paper and the second was reinforced with corn leaves and sheets of paper. For the two composite materials the same mechanical characteristics were determined as in the case of the hybrid resin. Finally, based on the determined properties, it is proposed to use these composites for the making of medical devices (used to immobilize fractures), of some furniture components, or some constructions formwork. [ABSTRACT FROM AUTHOR]

In this paper we have created some composites reinforced with corn cob powder and the matrix was made by a combination between Resoltech 1050 resin with its Resoltech 1058 hardener. For the composites manufacturing, we have used the manual casting technique. For the new manufactured composites, we have determined the mechanical properties from the tensile test according to ASTM D3039: Young modulus, breaking strength and elongation at break. We have also molded samples for the compression test according to ASTM D695-15 and we have determined the breaking strength. The tensile and compression tests were made on universal testing machines. In the end, we have determined also the dynamic mechanical properties for the studied material by clamping the samples at one edge and leaving the samples unconstrained at the other edge. At the unconstrained edge we have placed a Bruel&Kjaer accelerometer which recorded the samples free vibrations. From the free vibrations recording and Euler-Bernoulli theory, we have determined the next dynamic mechanical properties: damping factor per unit mass and length, eigenfrequency, dynamic modulus of elasticity, loss factor and dynamic rigidity. From the experimental results, we have obtained increased breaking strength values for the proposed material at compression compared to the tensile test. Compared to similar materials studied in the engineering literature, we have obtained increased compression breaking strength. [ABSTRACT FROM AUTHOR]

Great interest has been shown lately in bio-composite materials because they are inexpensive and sustainable. Composites with matrices and natural reinforcers have been little studied. Here, we study certain mechanical properties of composite materials with a Dammar-based matrix (also named hybrid matrix) and flax fabric reinforcement. To be precise, we examine three types of resins where Dammar is the major component, with a volume proportion of 55%, 65% and 75%. In this respect, we have made composite materials reinforced by two types of flax fabric and we have measured the characteristic curves and some mechanical properties, such as the Young's modulus, tensile strength and elongation at break using tensile tests. Based on the obtained properties, it is proposed or possible to use these materials in orthopedics. [ABSTRACT FROM AUTHOR]

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