Processing of polymer wood composite material from pine cone and the binder of phenol formaldehyde/PVAc/molasses and improvement of its properties

This paper deals with the processing of polymer wood composite material from pine cone and the binder of phenol formaldehyde/PVAc/molasses and improvement of its properties. The production of pine cone based polymer binding and molasses added composite material, and the development of the non-flammability, insect attack and water resistance properties of this material has been studied in the research. To this end, pine cone, polyvinyl acetate (PVAc), phenol-formaldehyde, molasses, hemp fiber and waste colemanite have been used in the production of composite materials. It is aimed to produce a cheaper composite material less harmful to human health using plant based waste materials. According to the results of the flexural strength test conducted in the laboratory, the most suitable composite material producing parameters were detected as 0.25 filler/binder (f/b) ratio, 35% molasses ratio, 100°C molding pressure temperature, 49 kg/cm2 molding pressure, 240 µm mean particle size, 20 minutes for molding pressure time, 20% PF ratio and 0.5% hemp fiber ratio. It was determined that molasses could be used at a ratio of 35% for producing composite materials and, PF resin and hemp fiber samples provide the necessary water resistance. It was observed that the colemanite waste used in the mixture adds the nonflammability property to the composite material and decreases flexural strength and screw withdrawal strength.

Recent Advances on the Development of Protein-Based Adhesives for Wood Composite Materials—A Review

The industrial market depends intensely on wood-based composites for buildings, furniture, and construction, involving significant developments in wood glues since 80% of wood-based products use adhesives. Although biobased glues have been used for many years, notably proteins, they were replaced by synthetic ones at the beginning of the 20th century, mainly due to their better moisture resistance. Currently, most wood adhesives are based on petroleum-derived products, especially formaldehyde resins commonly used in the particleboard industry due to their high adhesive performance. However, formaldehyde has been subjected to strong regulation, and projections aim for further restrictions within wood-based panels from the European market, due to its harmful emissions. From this perspective, concerns about environmental footprint and the toxicity of these formulations have prompted researchers to re-investigate the utilization of biobased materials to formulate safer alternatives. In this regard, proteins have sparked a new and growing interest in the potential development of industrial adhesives for wood due to their advantages, such as lower toxicity, renewable sourcing, and reduced environmental footprint. This work presents the recent developments in the use of proteins to formulate new wood adhesives. Herein, it includes the historical development of wood adhesives, adhesion mechanism, and the current hotspots and recent progress of potential proteinaceous feedstock resources for adhesive preparation.

Energy Saving Design of Exterior Envelope of Prefabricated Buildings in Alpine Area

In this paper, the exterior envelope of prefabricated buildings in alpine areas is studied. This paper compares the wind resistance of the fabricated structure composed of two different connection modes, connectors with different thickness, lightweight ceramsite concrete peripheral wall panel and wood composite peripheral wall panel. The test results show that the wind resistance of the fabricated structure composed of wood wallboard mainly depends on the thickness of wallboard, connection mode and connector thickness. Whether sand packing is filled or not has no effect on the improvement of wind resistance of this prefabricated enclosure structure. For meeting the wind resistance of the fabricated enclosure used in the support room, it is recommended to use thick wooden wallboard and connect up and down. The wind resistance of the fabricated enclosure composed of wood wallboard mainly depends on the strength of the wood wallboard itself. The use of wood wallboards with higher thickness can improve the wind resistance of this fabricated structure.

Nondestructive Testing of Mechanical Properties of Bamboo–Wood Composite Container Floor by Image Processing

The bamboo–wood composite container floor (BWCCF) has been wildly utilized in transportation in recent years. However, most of the common approaches of mechanics detection are conducted in a time-consuming and resource wasting way. Therefore, this paper aims to provide a frugal and highly efficient method to predict the short-span shear stress, the modulus of rupture (MOR) and the modulus of elasticity (MOE) of the BWCCF. Artificial neural network (ANN) models were developed and support vector machine (SVM) models were constructed for comparative study by taking the characteristic parameters of image processing as input and the mechanical properties as output. The results show that the SVM models can output better values than the ANN models. In a prediction of the three mechanical properties by SVMs, the correlation coefficients (R) were determined as 0.899, 0.926, and 0.949, and the mean absolute percentage errors (MAPE) were obtained, 6.983%, 5.873%, and 4.474%, respectively. The performance measures show the strong generalization of the SVM models. The discoveries in this work provide new perspectives on the study of mechanical properties of the BWCCF combining machine learning and image processing.

Enhancing the properties of damar (Agathis loranthifolia Salisb.) wood by making hybrid bamboo-wood composite

This study was carried out to investigate the characteristics of laminated bamboo and damar (Agathis loranthifolia Salisb.) wood as the core layer of the bamboo-damar hybrid composite beam. Andong bamboo (Gigantochloa pseudoarundinacea (Steud.) Widjaja) and mayan bamboo (Gigantochloa robusta Kurz.) were used as the face and back layers of the beam, glued with isocyanate adhesive. Four types of composite beam were produced with various number of laminated bamboo layers. Results showed that the four layers (two layers for each face and back sides) laminated andong bamboo performed superior mechanical properties than others hybrid composite beam, while the four layers (two layers for each face and back sides) laminated mayan bamboo demonstrated the highest compression and bonding strength. The density, MOR, MOE and compression strength of the hybrid composite beam improved 31.3%, 25.95%, 37.81% and 25.12%, respectively, as the outcomes of the incorporation of laminated andong bamboo on the outer layers of the damar board. This paper proves that the number of laminated bamboo layers enhances the properties of the bamboo-damar hybrid composite beam. Furthermore, it shows promising result for complementing furniture and interior design materials as the bamboo-damar hybrid composite beam has remarkable properties.

Additive Manufacturing of Wood Composite Panels for Individual Layer Fabrication (ILF)

The renewable resource, wood, is becoming increasingly popular as a feedstock material for additive manufacturing (AM). It can help make those processes more affordable and reduce their environmental impact. Individual layer fabrication (ILF) is a novel AM process conceived for structural applications. In ILF, parts are formed by laminating thin, individually contoured panels of wood composites which are fabricated additively by binder jetting. The individual fabrication of single panels allows the application of mechanical pressure in manufacturing those board-like elements, leading to a reduction of binder contend and an increase of mechanical strength. In this paper, the ILF process is described in detail, geometric and processing limitations are identified, and the mechanical properties of the intermediate product (panels) are presented. It is shown that the thickness of panels significantly influences the geometric accuracy. Wood composite panels from spruce chips and pMDI adhesive showed flexural strengths between 24.00 and 52.45 MPa with adhesive contents between 6.98 and 17.00 wt %. Thus, the panels meet the mechanical requirements for usage in the European construction industry. Additionally, they have significantly lower binder contents than previously investigated additively manufactured wood composites.