•Along grain sample has higher flame intensity than across grain sample.•Delamination has been observed in the burning of all along grain samples.•More fuel is consumed for along grain orientations ...and thicker samples.•Correlations for flame height and pyrolysis height are proposed.•Effects of grain orientation and sample thickness on heat transfer are revealed.
Corrugated cardboard is widely used in underground logistic transportation and warehousing and it has become an important fire hazard source. According to previous warehouse fire studies, upward flame spread on corrugated cardboard plays an important role during the initial stage of warehouse fires and can decide the occurrence of subsequent increasing fire hazards. However, the wavy structural effect of corrugated cardboard on fire spread still lacks enough attention. This work studies the fire spread behavior of vertically-set corrugated cardboard with thicknesses of 1.5 mm, 3.0 mm and 4.0 mm. The cardboard inner hollow gaps are set either parallel (defined as along grain direction) or perpendicular (defined as across grain direction) to buoyancy direction. Experimental results show that: (1) along grain sample has better flammability than across grain sample; (2) the relationship between flame height (or pyrolysis height) and time has a best fit with power law, and the difference of the exponents between two grain orientations decreases with the increasing of the sample thickness; (3) for cardboard of different grain orientations and thickness, the ratio of average flame height to average pyrolysis height is a constant. The hollow gaps inside along grain sample, working as passage, are beneficial for the transportation of heated pyrolysis gases and preheating of upper virgin area, hence increasing burning rate and flame upward spread. However, it is observed that the phenomenon (flame luminance, delamination of front layer, extinguishment of flame base, etc.) difference between different grain orientations decreases as sample thickness increases. This study reveals the effects of grain orientation and sample thickness on the corrugated cardboard fire spread behavior which is common in commodity fire in underground logistic transportation and warehousing. The conclusions are beneficial for fire risk assessment as well as the improvement of related codes and regulations.
The aim of this paper is to characterize the mechanical behavior of corrugated cardboard boxes using simple models that allow an approach to the load capacity and the deformation of the boxes. This ...is very interesting during a box design stage, in which the box does not exist yet. On the one hand, a mathematical model of strength and deformation of boxes with different geometry is obtained from experiments according to the Box Compression Test and Edge Crush Test standards. On the second hand, a finite element simulation is proposed in which only the material elastic modulus in the compression direction is needed. For that, corrugated cardboard sheets are glued to build billets for testing, and an equivalent elastic modulus is obtained. This idea arises from the fact that the collapse of the box is given by the local bucking of the corrugated cardboard panels, due to the slenderness itself, and the properties in the compression direction are predominant. As a result, the numerical models show satisfactory agreement with experiments, concluding that it is an adequate methodology to simulate in a simple and efficient way this type of boxes built with corrugated cardboard.
As long as non-contact digital printing remains an uncommon standard in the corrugated packaging industry, corrugated board crushing remains a real issue that affects the load capacity of boxes. ...Crushing mainly occurs during the converting of corrugated board (e.g., analog flexographic printing or laminating) and is a process that cannot be avoided. However, as this study shows, it can be controlled. In this work, extended laboratory tests were carried out on the crushing of double-walled corrugated board. The influence of fully controlled crushing (with a precision of ±10 μm) in the range from 10 to 70% on different laboratory measurements was checked. The typical mechanical tests—i.e., edge crush test, four-point bending test, shear stiffness test, torsional stiffness test, etc.—were performed on reference and crushed specimens. The residual thickness reduction of the crushed samples was also controlled. All empirical observations and performed measurements were the basis for building an analytical model of crushed corrugated board. The proven and verified model was then used to study the crushing effect of the selected corrugated board on the efficiency of simple packages with various dimensions. The proposed measurement technique was successfully used to precisely estimate and thus control the crushing of corrugated board, while the proposed numerical and analytical techniques was used to estimate the load capacity of corrugated board packaging. A good correlation between the measured reduced stiffness of the corrugated cardboard and the proposed analytical predictive models was obtained.
In this paper, a new designed silicon-containing nitrogen and phosphorus flame-retardant system containing ammonium polyphosphate, modified molecular sieve and methylcellulose was used to prepare the ...flame-retardant corrugated cardboards (FRCCB). The samples before and after treatment were tested for combustion and thermal stability using vertical burning test (VBT), limiting oxygen index (LOI), cone calorimetric test (CCT) and thermogravimetry (TG). To further analyze the flame-retardant properties of the flame-retardant system, the microstructure, surface elements and functional groups of the materials were characterized by the scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the samples were tested to analyze the effect of flame-retardant treatment on the strength. The VBT and LOI tests showed that the samples after the flame-retardant treatment were able to self-extinguish after ignition, achieving the flame-retardant B-1 grade. The CCT tests showed that the total heat release of treated samples was reduced by 49.90%, and the total smoke production was decreased by 27.64%. TG tests showed that the thermal decomposition temperature of FRCCB decreased but the residual carbon content increased largely. FTIR tests showed that the functional group changed at different temperatures. After flame-retardant treatment, a dense carbon layer was formed on the surface of the treated sample, including N, P, Si and Cu, measured by SEM and EDS. Combining with various characterization methods, the flame-retardant system can retard flame by releasing nonflammable gases, forming covers and catalyzing char formation.
In the construction sector, the new Industry 4.0 and circular economy paradigms are currently playing an increasingly important role in order to respond to demands for energetic efficiency, ...optimisation of resource usage, automation and production activities monitoring. Therefore, this article aims to at illustrate industrial research and an experimental development activity that led to the creation of an innovative product named MULTIFId. It consists of an intelligent, economical and low-emission panel, made with waste from the paper and cardboard industrial manufacturing process which intends to contribute to the development of the fundamental enabling technology of “Advanced Materials” for Intelligent Factories.
This article focuses on the derivation of simplified predictive models for the identification of the overall compressive stiffness and strength of corrugated cardboards. As a representative example ...an unsymmetrical 5-ply sample (with E and B flute) was used in this study. In order to exclude unreliable displacement measurement in the standard edge crush test, virtual strain gauges were used. Video extensometry was employed to collect measurements from the outer surfaces of the sample on both sides. Additional data allowed real force-displacement curves to be obtained, which were used in the validation procedure. To emulate the experimental results, besides a simple analytical model, a 3D numerical model fully reflecting the geometry of the corrugated board, based on the finite elements method was also built. In both cases good agreement between the experimental results and the analytical and numerical calculations was observed. This proved that the proposed analytical model can be successfully used to determine the overall stiffness and compressive strength of corrugated board, provided that the geometry and properties of all the layers of the board are known. The simple model presented in this work enables quick and reliable design and prototyping of new assemblies without the need to manufacture them.
The Elmendorf method is a well-known test that provides valuable insight into the durability and lifespan characteristics of the observed material, i.e., paper or paperboard. The objective of this ...paper is to determine if it is possible to apply the Elmendorf test to perforated corrugated cardboard to measure tear resistance. An Instron tensile tester was used to obtain input data for a range of properties of perforated corrugated board and to validate the non-standard test technique. Correlation analysis was used to statistically verify and quantify the relationship between the results obtained by the two aforementioned methods. Specimens were cut from four different qualities of three-layer E-flute corrugated cardboards at five defined angles affected by five types of perforations. First, the graphical difference in Least Square mean values was analysed and the results were confirmed by correlation analysis. No significant difference in results between the two observed methods was determined, and the relationship was mostly interpreted as a high positive correlation. Therefore, the results obtained by the Elmendorf method can be used for a better understanding of the mechanical properties of perforated corrugated cardboard.
The edge crush test is the most popular laboratory test in the corrugated packaging industry. It measures the edge crush resistance of a sample in the cross-fiber direction (CD), also known as the ...ECT index. This parameter is widely used for the specification of the board by its producers. It is also utilized in most analytical formulas describing the load capacity of the packaging. On the other hand, the ECT value can be estimated from both analytical and numerical models based on the basic parameters of each constituent paper. Knowing the compressive strength in CD (commonly known as SCT) and the elastic properties of the individual layers, the sample geometry (i.e., the period and height of the corrugated layer), as well as the boundary conditions, the ECT value can be calculated. This is very useful as new boards can be virtually analyzed before being manufactured. In this work, both detailed numerical models based on finite elements (FE) methods and very simple analytical (engineering) models were used for the ECT calculations. All presented models were validated with experimental data. The surprising consistency and high precision of the results obtained with the simplest approach was additionally analyzed in the study.
Recent European regulations have imposed ecological alternatives to the packaging of expanded polystyrene (EPS) dairy products. In this study we explore the opportunity to replace the expanded ...polystyrene packaging, with a corrugated cardboard coated with bioplastic for the storage and transport of cheese and mozzarella. Life cycle analysis (LCA) indicates that the use of bioplastic coated corrugated board could significantly reduce the packaging's carbon footprint. Corrugated board has a lower environmental impact than polystyrene, except for the ecosystem quality indicator. This indicator is worse for corrugated because of the impacts associated with the cultivation of corn and sugar cane needed for bioplastics production, as well as the deforestation associated with paper production. EPS, on the other hand, is more impactful due to oil extraction and disposal processes such as landfill and incineration. From the analysis of defined sensitivity by increasing the percentage of composting and recycling, there is an improvement in the environmental performance of coated board, even in critical categories. Therefore, the latter scenario is the ideal and desired solution to obtain the replacement of EPS packaging with bioplastic coated cardboard.
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