ISO Standard UNI EN Research Articles

Preparation and characterization of innovative poly(butylene adipate terephthalate)‐based biocomposites for agri‐food packaging application

AbstractThe present work reports on the preparation and subsequent mechanical, morphological and thermal characterization of composites based on poly(butylene adipate terephthalate) (PBAT), reinforced with micro‐particles of inorganic bioabsorbable calcium‐phosphate glass (CPG) at different contents up to 40 wt%. The PBAT‐CPG composites were prepared by solvent casting. The resulting composite pellets were used for the injection molding of model 1BA specimens, according to standard UNI EN ISO 527. PBAT‐CPG composites displayed an effective increase of the Young's modulus (E) up to 82% compared to the pristine polymer, while showing a reduction of the yield stress (σy) up to 20%, of the stress at break (σB) up to 46%, of the strain at break (εB) up to 57% and of the toughness (T) up to 72%. The values of E, σy and σB were also compared and validated with theoretical values calculated using Kerner's and Pukanszky's models. Scanning electron microscopy (SEM) images display homogeneous dispersion and distribution of the filler particles in the polymer matrix with no aggregates or phase separation that would cause a deterioration of the material properties. Infrared (IR) spectroscopy did not show structural variations of the polymer matrix due to the CPG presence. The oxygen permeability in PBAT‐based samples assumes significantly lower values when benchmarked with the permeability of low‐density polyethylene (LDPE). Among the different composites, a decrease in oxygen permeability is observed as the CPG concentration increases. Regarding water vapor permeability, PBAT‐based samples show a lower barrier effect than polyethylene (PE): in particular, permeability to water vapor assumes an increasing trend as the quantity of filler increases. The tuneable degradation of the final composite materials was defined by the disintegration degree (DD) determination under composting conditions in a laboratory‐scale reactor. The developed materials prove to be valid biodegradable and eco‐friendly alternatives to traditional thermoplastic polymers, such as LDPE, and can be applied in many fields, especially in package and mulch film applications.

Experimental investigation on the effect of laser powder bed fusion process variables on dimensional accuracy, surface roughness and cylindricity of the AlSi10Mg alloy component

The present study deals with the influence of laser powder bed fusion process parameters on the selected linear dimension, surface roughness and cylindricity of AlSi10Mg alloy for manufacturing of a prototype connecting rod. The process variables used in this investigation are laser power, laser velocity, layer thickness and scanning speed. Response surface methodology is used to perform experiments and data analysis. The levels of process parameters are same that is, five for all the selected input process variables. An automotive component connecting rod is used as a component to analyze the effect of process variables on selected response variables. The optimum sating of process variables are different for dimensional accuracy, surface roughness and cylindricity. Minitab 14 software is used for the data analysis. The international tolerance grades of confirmation experiments are calculated as per the ISO standard UNI EN 20286-I and DIN 16901. A quadratic regression models are developed to estimate the response variables in terms of process parameters. The model is adequate within the experimental domain. X-chart of confirmation experiments is plotted. The deviation in the linear dimension is within the limit of ±3 sigma (σ). The lowest values of response variables at the best level of process parameters are obtained, that is, percentage error in dimensional accuracy of 2.65%, surface roughness of 2.57 µm and cylindricity of 0.09 mm. The novelty of this work lies in the fact that only a few studies have been conducted related to the form errors in the archival literature.

Hourly dynamic and monthly semi-stationary calculation methods applied to nZEBs: Impacts on energy and comfort

The EU Directive 2010/31 abstained from prescribing harmonized and strict requirements for nearly Zero Energy Buildings (nZEBs), to provide EU countries flexibility and room for maneuver in setting national targets, in view of the impact of local climatic conditions and specific territorial and socio-economical features on heating and cooling needs. Benchmarks are usually provided in terms of primary energy needs, however the definition of accurate calculation methodologies, notably as regards the cooling share, is a rather challenging task. Nonetheless, its accomplishment is cardinal to countries, like Mediterranean ones, were the building performance is mostly dictated by summertime sensitivities. This paper presents a cutting-edge approach to nZEB performance analysis: the monthly quasi steady-state (EN 13790 as implemented in Italian UNI/TS 11300) and hourly dynamic calculation methods (developed under the standard UNI EN ISO 52016-1:2018) are compared, with due attention to the cooling energy consumption, to spot pros and cons of a finer temporal discretization. Potential nZEB design alternatives in three different Italian climatic zones are contemplated and used to confront the effectiveness of the above procedures.

Polycaprolactone-collagen hydrolysate thermoplastic blends: Processability and biodegradability/compostability

Thermoplastic blends of polycaprolactone (PCL) and hydrolyzed collagen (HC) derived from the tannery industry were investigated to assess the feasibility of producing by conventional melting-based procedures biodegradable items for applications in agriculture and plant nurseries. The used HC was obtained by alkaline hydrolysis of the shavings of the tanning process. PCL/HC blends, with 10, 20 and 30 wt.% of HC, were processed by extrusion and compression molding, and characterized in terms of thermal, rheological, morphological and mechanical properties. In view of their possible applications in agriculture, phytotoxicity assays were carried out by using cress (Lepidium sativum L.) germination test and growth analyses of lettuce plants (Lactuca sativa L., cv Canasta), used as reference. Small pots were produced by fused deposition modeling (FDM) and their compostability was evaluated by the standard disintegration test UNI EN ISO 14045. The ultimate aerobic biodegradability of the blends was assessed by the standard UNI EN ISO 14855-1. PCL/HC blends were successfully processed by extrusion providing cohesive and flexible filaments suitable for the FMD 3D-printing. A decrease in the melt viscosity was observed with the addition of HC due to its plasticizing effect. The addition of HC led to a clear decrease of the tensile modulus and, with 30 wt.% HC, a break elongation higher than 600% as pure PCL. Despite the release in water of soluble salts, responsible of a moderate phytotoxicity assessed by L. sativum germination test, PCL/HC blends were not phytotoxic to the lettuce growth. Moreover, PCL/HC blends showed very high biodegradation rates in compost, even higher than cellulose. Composting trial performed under real conditions also confirmed the biodegradability of these blends, showing complete disintegration of the produced 3D printed pots in just 30 days.

Experimental investigations for dimensional accuracy and surface finish of polyurethane prototypes fabricated by indirect rapid tooling: a case study

In this research work, an effort has been made to study the influence of selected input parameters on the dimensional accuracy (linear as well as radial) and surface finish of polyurethane prototypes fabricated by vacuum casting (VC) process as a case study. The master pattern required for making a silicone mould has been fabricated by fused deposition modelling and its surface finish has been enhanced by chemical vapour smoothing process. Maximum shrinkage of 2.29 and 4.77% has been observed in the selected linear and radial dimension, respectively, after the VC process. Optimal parameter settings that were different for both the dimensions as well as surface finish have been obtained using Taguchi’s L18 orthogonal array. Finally, parameter setting that simultaneously minimizes the dimensional deviation and surface roughness has been found out using response optimization module of Minitab 17 software and the results obtained have been verified by performing the confirmation experiments. The tolerance grades for the selected dimension of the prototypes were found to be acceptable as per the ISO standard UNI EN 20286-I (1995) and DIN16901 for plastic materials. In addition, the C pk value greater than 1.3 indicated that the proposed process is highly capable. The surface finish and dimensional accuracy of prototypes are at par with the traditional moulding patterns, and hence, they can be used as end-products or plastic-based master patterns for investment casting applications.

Dimensional accuracy and surface finish of biomedical implant fabricated as rapid investment casting for small to medium quantity production

In this work the feasibility of combined route of fused deposition modelling (FDM), chemical vapor smoothing (CVS), vacuum casting (VC) and investment Casting (IC) for the development of customized implant for small to medium quantity production has been investigated. Further, an effort has been made to optimize the dimensional accuracy and surface finish of the implant (hip joint) prepared by varying two controllable factors (namely: drying time of primary coating and mould thickness) each at three levels of the IC process. The master pattern of the hip joint has been prepared by FDM followed by the CVS process to enhance the surface finish and multiple replicas were produced by the VC process for batch production. The tolerance grades for the selected dimension of the implant/castings were found to be acceptable as per the ISO standard UNI EN 20286-I (1995). Also, the Cpk value greater than 1.3 indicated that the proposed process is statistically controlled.

Repeatability of linear and radial dimension of ABS replicas fabricated by fused deposition modelling and chemical vapor smoothing process: A case study

In this research work, an effort has been made to study the influence of fused deposition modelling (FDM) and chemical vapor smoothing (CVS) process parameters on the selected linear and radial dimension as well as on repeatability of acrylonitrile butadiene styrene (ABS) replicas as a case study. The study highlights that orientation of parts on FDM build platform, part density (part interior style) and interaction between these two parameters significantly affect the accuracy of selected dimensions. Shrinkage has been observed in the selected radial dimension of the prototypes, but there is a positive deviation in the linear dimension from the desired value. The CVS process reduces both the dimensions slightly due to reflow of the material. Optimum parameter settings that were different for both linear and radial dimensions have been investigated using Taguchi’s L18 orthogonal array. The IT grades of ABS replicas prepared by this combined process were found to be consistent with the permissible range of tolerance grades as per ISO standard UNI EN 20286-I (1995) and DIN 16901 for plastic materials. Finally, optimum level of process parameters that simultaneously minimizes the deviation in both the dimensions have been found out using response optimization module of Minitab 17 software and the results obtained have been verified by performing the confirmation experiments.

Process capability study of three dimensional printing as casting solution for non ferrous alloys

Purpose The purpose of this paper is to investigate the process capability of three-dimensional printing (3DP)-based casting solutions for non-ferrous alloy (NFA) components. Design/methodology/approach After selection and design of benchmark, prototypes for six different NFA materials were prepared by using 3DP (ZCast process)-based shell moulds. Coordinate measuring machine has been used for calculating the dimensional tolerances of the NFA components. Consistency with the tolerance grades of the castings has been checked as per IT grades. Findings The results of process capability investigation highlight that the 3DP process as a casting solution for NFA component lies in ±5sigma (s) limit, as regards to dimensional accuracy is concerned. Further, this process ensures rapid production of pre-series industrial prototypes for NFA. Final components prepared are also acceptable as per ISO standard UNI EN 20,286-I (1995). Originality/value This research work presents capability of the 3DP process supported with experimental data on basis of various process parameters for the tolerance grade of NFA castings. These statistics can help to enhance the application of 3DP-based NFA casting process in commercial foundry industry.

Effects of Inhomogeneities on Heat and Mass Transport Phenomena in Thermal Bridges

The interest of calculating the effects of thermal bridges in buildings energy consumption is growing, due to recent energy saving regulations applied in different countries. The widespread use of insulating materials to reduce energy requirements of buildings, often employed for intermediate insulation of the building envelope, makes thermal bridges a crucial point in the energy analysis of building envelopes. Furthermore, heat losses through thermal bridges often lead to building pathologies due to moisture condensation. Therefore, thermal bridges need to be correctly characterized in the building design stage in order to reduce heat losses and avoid materials degradation. The authors numerically simulate, by using finite elements, the steady-state and dynamic three-dimensional (3D) heat and vapor transport in inhomogeneous thermal bridges and building envelopes. The aim of the present work is to show the importance of taking into account the presence of inhomogeneities (i.e., metal stud) in building materials for the calculation of actual heat losses and water condensation in 3D thermal bridges. The obtained heat transfer results are verified against the reference data of the technical standard UNI EN ISO 10211. The proposed microscopic approach is essential to calculate the actual heat losses of three-dimensional thermal bridges and building envelopes and to overcome condensation problems.

Some critical remarks about the radiative heat transfer in air frame cavities according to EN ISO 10077-2

Thermal performances of windows frames are established, in Europe, by the international standard UNI EN ISO 10077-2:2012. The standard introduces an equivalent thermal conductivity for air frame cavities thus simplifying the original combined heat transfer problem to a merely two-dimensional conductive one. The equivalence is referred to a rectangular cavity and is not able to fully recover the same radiative heat flux involved in the original problem. In view of that, the paper is focused on the radiative heat transfer taking place in the air cavities and aims to check if different equivalence criteria could lead to improved results. Thus, numerical tests involving an accurate description of radiative heat transfer in air cavities are compared to the simplified fully-conductive one provided by the standard. Results show that different criteria lead to quite different results. The optimal criterion turns out to depend on both geometrical and surface radiative parameters. It is also shown that, in any case, a proper radiative resistance but not the one suggested by the ISO 10077 should be adopted.

In Situ Thermal Transmittance Measurements for Investigating Differences between Wall Models and Actual Building Performance

An accurate assessment of a building’s wall performance, defined through the thermal transmittance, is essential to compute the annual energy consumption. Analyzing opaque surfaces, the heat transfer across walls can be modeled by an electro-thermal analogy, based on resistors series, crossed by a one-dimensional heat flow. This analogy is well established and it refers to stratigraphy composed of homogeneous materials. When dealing with inhomogeneous materials, possibly including hollow bricks, the wall’s thermal transmittance is evaluated by means of an effective conductance. However, in order to verify the theoretical models effectiveness, a comparison with in situ measurements is needed. In this paper, three building walls characterized by different stratigraphy have been analyzed; by employing a heat flow meter investigation. Measurements results and estimated thermal transmittance values—calculated applying the standard UNI EN ISO 6946—have been compared.

Experimental investigations and statistical analysis of regular open cell porous metallic structure fabricated through rapid manufacturing

Three dimensional open cell porous with regular pore distributed metallic structure of phosphorus bronze has been analysed statistically. The fabrication of open cell porous structure was carried out with the combination of 3-D printing and pressureless sintering process. The dimensional measurements were carried out using coordinate measuring machine and digital microscope. The measurement showed dimensional deviation up to 4.89% for the characteristics length, width and height while dimensional deviation of 15 to 19.16%, for pores and struts, have been observed. The tolerance grades of IT15 to IT16 have been found for all the characteristics in accordance with ISO standard UNI EN 20286-I (1995). The dimensional data showed no abnormality like clustering, mixture, trends, oscillation and confirm the tests for randomness and normality. The results of analysis showed to have a greater probability of this process to lie under statistical control.

Environmental analysis of geothermal heat pump and LPG greenhouse heating systems

The use of low-impact energy sources for greenhouse cultivations is growing quickly due to environmental demands, constrained by the increased price of fossil energy sources, market demand for low cost greenhouse production, and need for air pollution reduction. This paper demonstrates via environmental analysis the efficiency of a Photovoltaic-Geothermal Heat Pump integrated system (PV-GHP) as a greenhouse heating system, compared to a conventional hot air generator using liquefied petroleum gas (LPG-HG). The tests were carried out in twin experimental greenhouses in the Mediterranean area (Valenzano-Italy). In order to evaluate the environmental performance of a heat pump system with electricity supplied from the national grid, a scenario (GHP Geothermal Heat Pump) was realised. The microclimatic conditions in the two greenhouses, the thermal energy produced, and the electricity consumption were analysed. Furthermore, in order to evaluate the long-term environmental impact, an environmental analysis was conducted using life cycle assessment (LCA) methodology, carried out according to standard UNI EN ISO 14040. The interpretation of the results using method CML2001 (Centre of Environmental Science, Leiden, Netherlands) showed that neither system is more advantageous from an environmental point of view and that the GHP scenario has the higher environmental burdens. Limiting the analysis to the emissions responsible for the greenhouse effect, the plant with the geothermal heat pump and photovoltaic panels reduces carbon emissions by 50%. In order to assess the sustainability of the geothermal heat pump plant, the estimated payback-time for energy and for carbon emissions were 1 year and 2.25 years, respectively.

Process capability analysis of fused deposition modelling for plastic components

Purpose – The purpose of the present study is process capability analysis of fused deposition modelling (FDM) process as rapid pattern making (RDPM) solutions for plastic components. Design/methodology/approach – Starting from the identification of component, prototypes with ABS plastic material were produced and dimensional measurements were made with coordinate measuring machine (CMM). Some important mechanical properties were also compared to verify the suitability of the components. Findings – The study highlighted the best settings of orientation, support material quantity for the selected component as a case study on FDM machine from dimensional accuracy and economic point of view as RDPM solution for plastic components. Practical implications – This process ensures rapid production of statistically controlled pre-series technological prototypes and proof of concept at less production cost and time. Final components produced are acceptable as per ISO standard UNI EN 20286-I and DIN16901. Originality/value – The results of the study suggest that FDM process lies in ±4.5 sigma (σ) limit in regard to dimensional accuracy of plastic component is concerned and may be gainfully employed as RDPM solution for bio-medical applications.

Dimensional Accuracy Comparison of Investment Castings Prepared with Wax and ABS Patterns for Bio-medical Application

In this research work comparison has been made for dimensional accuracy of hip joint prepared by investment castings process using conventional wax and acrylonitrile butadiene styrene (ABS) as pattern material. Two controllable process variables namely: numbers of slurry layers and type of pattern material have been considered for comparison. An approach to model dimensional accuracy of hip joint has been proposed and applied. International tolerance (IT) grade of cast components was tested and found acceptable as per ISO standard UNI EN 20286-I (1995) and further at proposed parametric settings, process has been found to be statistically controlled.

Microbiological and chemical contamination in different types of food of non-European origin

In the markets of the European Union (EU) the presence of food imported from non-European countries such as Asia, Africa and America is increasingly more widespread. Non-European countries, indeed, are much more competitive in terms of prices compared to European countries. For these reasons, EU has issued important laws. The purpose of this study was to assess the effectiveness of these regulations, estimating the levels of microbiological and chemical contamination of food samples of 91 different matrices imported from third countries. The microbiological methods used are those required by the UNI EN ISO, while for the determination of chemical parameters validated methods according to the Standard UNI EN ISO 16140:2003 were used. Our investigation revealed qualitative or quantitative microbial contamination in 23 out of 91 samples analysed (25.2%). We found high total microbial loads in alimentary conserves, multiple bacterial contamination ( Salmonella thiphymurium , Escherichia coli and Vibrio alginolyticus ) and viral contamination ( Norovirus ) in shellfish of the species Cassostrea gigas , and the presence of other pathogens in various products such as hamburgers ( Yersinia enterocolitica ), frozen fish ( Listeria monocytogenes ) and honey ( Bacillus cereus ). With regard to chemical contamination, 24 samples of different food products were analysed. In 9 samples (37.5%), the levels of the following substances exceeded the permitted limits: histamine (fish conserves), mercury (crab meat), cadmium (crab meat and fish conserves), lead (cheese and honey) and polyphosphates (chicken meat). Despite the limited number of samples analysed, these data prompt reflection on the need to implement a more detailed and rigorous activity of monitoring and control in order to guarantee adequate levels of safety with regard to the consumption of foodstuffs imported into the EU from non-European countries.

English

The purpose of this paper is to examine the suitability of fused deposition modelling (FDM), for the production of a pattern that can be used in direct manufacturing applications. In this work, the benchmark was identified and its best part orientation in a FDM machine was located through experimentation. Control charts and process capability histogram were drawn to assess the process capability of the FDM process. The micro hardness of the prepared sample was measured to check the suitability of the process for investment casting applications. Further dimensional accuracy of patterns was established by IT grades as per the ISO standard UNI EN 20286-I (1995). It was observed that the performance indices for all the dimensions in the present study are greater than 1. The study of photo micrographs using SEM gave an insight into the properties of the component (produced by FDM). This study highlights that the tolerance grades for ABS plastics are consistent with the permissible range of tolerance grades as per the ISO standard UNI EN 20286-I (1995) and DIN16901 standard.

Process Capability Analysis of Vacuum Moulding for Development of Al-Al2O3 MMC

The purpose of the present study is to investigate process capability of vacuum moulding (VM) for development of Al-Al2O3 metal matrix composite (MMC). Starting from the identification of component, prototypes were prepared (with three different input parameters namely: vacuum pressure; component volume and sand grit size to give output in form of dimensional accuracy). Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the Al-Al2O3 MMC prepared. Some important mechanical properties were also compared to verify the suitability of the components. Final components produced are acceptable as per ISO standard UNI EN 20286-I (1995). The results of study suggest that VM process lies in ±4.5 sigma (σ) limit as regard to dimensional accuracy of Al-Al2O3 MMC is concerned. This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.

English

The purpose of the present work is to study the effect of workpiece volume on reducing the shell wall thickness in rapid shell casting based upon three-dimensional printing (3DP) technology, and to evaluate the dimensional accuracy and mechanical properties of aluminum (Al) castings obtained as per the ISO standard UNIEN 20286-I (1995). Starting from the identification of component/benchmark, castings of different volumes (corresponding to workpieces of ɸ60 mm, ɸ50 mm and ɸ40 mm) were produced with different shell wall thicknesses. Measurements on a coordinate measuring machine (CMM) allowed the calculation of the dimensional tolerances of the castings produced. Some important mechanical properties were also compared to verify the suitability of the castings. The research proved that having a shell wall thickness with a value less than that recommended (12 mm) is more suitable from a dimensional accuracy and economic point of view (irrespective of the workpiece volume within the given selected range). All the castings produced with different shell thicknesses are acceptable as per the ISO standard. The results of the study suggest that workpiece volume has an unnoticeable effect on reducing the shell wall thickness for the selected range of volumes of casting. Furthermore, the hardness of castings produced is almost same for all shell wall thicknesses, from 12 mm to 1 mm. The results are supported by cooling (time-temperature) curves, which show unnoticeable changes in the rate of heat transfer at different shell wall thicknesses. Keeping in mind the cost effectiveness of the process, one (1) mm shell wall thickness has been recommended for the production of castings. For a 1 mm shell wall thickness, the production cost and time are reduced by 67.38% and 44.87% (for ɸ60 mm workpieces), 64.51% and 44.62% (for ɸ50 mm workpieces), and 69.50% and 59.64% (for ɸ40 mm workpieces), respectively.

Building–plant system energy sustainability. An approach for transient thermal performance analysis

The aim of this research is to investigate the thermophysical behaviour of building envelope multi-layer components and assess the whole building–plant response. The investigation was carried out in two different phases. The first phase concerned the study of the dynamic response of building envelope multi-layer components, by providing an improved implementation of the present European Standard UNI EN ISO 13786:2008. The proposed method allows one to determine the transient thermophysical performance of opaque building components that are associated with a thermal zone maintained at constant or variable air temperature. The variable internal air temperature can be associated with experimental data. The second phase consisted of a transient analysis of the above thermal zone with a conditioning plant working. The building plant simulations were carried out by EnergyPlus software. The method proposed, based on European standards, is particularly useful in the perspective of the Certification of the Energy Performance of the building–plant system, required by the European Union. It can provide a useful tool for developing an abacus of different envelope multi-layer component performances in order to support design choices.