Influence of injection molding parameters on the morphology, mechanical and surface properties of ABS foams

In this work, microcellular ABS foams were studied. A series of injection molding samples defined by a design of experiments was carried out to analyze the effect of shot volume, mold temperature, and injection velocity on the morphology, mechanical properties, and surface roughness of microcellular samples. A predominant influence of shot volume on the cell structure and tensile properties was evidenced. Higher cell densities and narrower cell size distributions were obtained at lower injection volume. However, elastic modulus and tensile strength were improved by increasing the shot size. The effect of mold temperature and injection velocity was secondary. Higher levels of mold temperature and injection rate provided finer cell morphologies, but their effects on the elastic modulus and tensile strength were negligible. The decrease in shot volume and increase in gas content led to poor surface quality, whereas it was greatly improved by raising both mold temperature and injection velocityPostprint (author's final draft

Microcellular injection moulding: a comparison between MuCell process and the novel micro-foaming technology IQ Foam

The present work aims to compare two different injection moulding foaming technologies, the already known MuCell® process and the new emerged technology IQ Foam®, as well as the cell structure and mechanical behavior of the obtained components. Glass fiber reinforced-polypropylene (>PP GF<) was employed to produce rectangular plates at solid and foamed conditions by using MuCell® and IQ Foam® processes combined with the complementary Core Back expansion molding technology, and the material structure as well as the tensile, flexural and impact properties were studied. A solid skin-foamed core structure was observed in the samples foamed by both techniques. The mechanical properties decreased gradually with the apparent density of the microcellular plates. By increasing the thickness of the part because of the expansion of the cavity with the Core Back technology, the apparent density decreased but the flexural stiffness was greatly enhanced. Foamed samples obtained by IQ Foam® technology exhibited thicker solid surface layers and lower cell density than that of the MuCell® ones, but consequently higher resistant area, and thus, slightly higher mechanical properties. The new IQ Foam® technology is able to produce foamed parts with properties comparable to that of the MuCell® process, offering additional benefits such as cost-effectiveness, easy to use and machine-independencePostprint (author's final draft

Effectiveness of an mHealth intervention combining a smartphone app and smart band on body composition in an overweight and obese population: Randomized controlled trial (EVIDENT 3 study)

Background: Mobile health (mHealth) is currently among the supporting elements that may contribute to an improvement in health markers by helping people adopt healthier lifestyles. mHealth interventions have been widely reported to achieve greater weight loss than other approaches, but their effect on body composition remains unclear. Objective: This study aimed to assess the short-term (3 months) effectiveness of a mobile app and a smart band for losing weight and changing body composition in sedentary Spanish adults who are overweight or obese. Methods: A randomized controlled, multicenter clinical trial was conducted involving the participation of 440 subjects from primary care centers, with 231 subjects in the intervention group (IG; counselling with smartphone app and smart band) and 209 in the control group (CG; counselling only). Both groups were counselled about healthy diet and physical activity. For the 3-month intervention period, the IG was trained to use a smartphone app that involved self-monitoring and tailored feedback, as well as a smart band that recorded daily physical activity (Mi Band 2, Xiaomi). Body composition was measured using the InBody 230 bioimpedance device (InBody Co., Ltd), and physical activity was measured using the International Physical Activity Questionnaire. Results: The mHealth intervention produced a greater loss of body weight (–1.97 kg, 95% CI –2.39 to –1.54) relative to standard counselling at 3 months (–1.13 kg, 95% CI –1.56 to –0.69). Comparing groups, the IG achieved a weight loss of 0.84 kg more than the CG at 3 months. The IG showed a decrease in body fat mass (BFM; –1.84 kg, 95% CI –2.48 to –1.20), percentage of body fat (PBF; –1.22%, 95% CI –1.82% to 0.62%), and BMI (–0.77 kg/m2, 95% CI –0.96 to 0.57). No significant changes were observed in any of these parameters in men; among women, there was a significant decrease in BMI in the IG compared with the CG. When subjects were grouped according to baseline BMI, the overweight group experienced a change in BFM of –1.18 kg (95% CI –2.30 to –0.06) and BMI of –0.47 kg/m2 (95% CI –0.80 to –0.13), whereas the obese group only experienced a change in BMI of –0.53 kg/m2 (95% CI –0.86 to –0.19). When the data were analyzed according to physical activity, the moderate-vigorous physical activity group showed significant changes in BFM of –1.03 kg (95% CI –1.74 to –0.33), PBF of –0.76% (95% CI –1.32% to –0.20%), and BMI of –0.5 kg/m2 (95% CI –0.83 to –0.19). Conclusions: The results from this multicenter, randomized controlled clinical trial study show that compared with standard counselling alone, adding a self-reported app and a smart band obtained beneficial results in terms of weight loss and a reduction in BFM and PBF in female subjects with a BMI less than 30 kg/m2 and a moderate-vigorous physical activity level. Nevertheless, further studies are needed to ensure that this profile benefits more than others from this intervention and to investigate modifications of this intervention to achieve a global effect

Microcellular PP/GF composites: morphological, mechanical and fracture characterization

The aim of the present work is to analyze the morphology, mechanical properties and fracture behaviour of solid and foamed plates made of glass fiber-reinforced PP. The morphology exhibited a solid skin/foamed core structure, dependent on the foaming ratio. Simulation of the microcellular injection molding process with Moldex 3DR software provided a good approach to the experimental results. The flexural properties and impact resistance showed lower values as the apparent density decreased, but constant specific properties. The fracture characterization was carried out by determining the Crack Tip Opening Displacement (CTOD) at low strain rate, as well as the fracture toughness (KIc) at impact loading. Foamed specimens presented higher values of CTOD than the solid ones and higher as the foaming ratio increases, due to cells acting as crack arrestors by blunting the crack tip. However, the fracture toughness KIc decreased with decreasing the apparent density. Anisotropy due to fiber orientation was also observed. Fibers were aligned in the filling direction in the surface layers, while they were oriented in the transverse direction in the core. According to the amount of fibers oriented in one direction or another, different properties were obtainedPostprint (author's final draft

Characterization of microcellular plastics for weight reduction in automotive interior parts

The present work deals with foaming plastic materials in order to reduce weight, cost and carbon footprint in automative parts. Glass-fiber-reinforced polypropylene (PP GF) was injection-modded in the solid and foamed states by means of the already known MuCell process and a newly emerged technology. IQ Foam, developed by Volkswagen AG. Both processes were combined with the complementary tool technology of core-back expansion molding. By increasing the thickness of the part, the apparent density decreased but the flexural stiffness was greatly enhanced. The new IQ Foam technology is able to produce foamed parts with properties compareble to that of the MuCell process, offering additional benefits such as cost-effectiveness, ease of use and machine-independence.Postprint (published version

Characterization of microcellular plastics for weight reduction in automotive interior parts

The present work deals with foaming plastic materials in order to reduce weight, cost and carbon footprint in automative parts. Glass-fiber-reinforced polypropylene (PP GF) was injection-modded in the solid and foamed states by means of the already known MuCell process and a newly emerged technology. IQ Foam, developed by Volkswagen AG. Both processes were combined with the complementary tool technology of core-back expansion molding. By increasing the thickness of the part, the apparent density decreased but the flexural stiffness was greatly enhanced. The new IQ Foam technology is able to produce foamed parts with properties compareble to that of the MuCell process, offering additional benefits such as cost-effectiveness, ease of use and machine-independence

Lightweighting of PP/GF: foamed composites for automotive applications

El aligeramiento de peso es una de las principales estrategias llevadas a cabo por los fabricantes de automóvile s para reducir consumo de combustible y emisiones de gases de efecto invernadero. Debido a la creciente demanda creciente de plásticos y materiales compuestos para aplicaciones de automoción, algunas tecnolo gías como la espumación han sido adoptadas para reducir su peso. El presente trabajo tiene como objetivo compara la morfología y propiedades mecánicas de plásticos espumados obtenidos mediante dos tecnologías de espumación distintas: MuCell® y IQ Foam®. Pl acas macizas y espumadas de polipropileno reforzado con fibra de vidrio (PP/GF) fueron obtenidas mediante moldeo por inyección utilizando los procesos MuCell® y IQ Foam® en combinación con la tecnología de expansión de molde Core Back. La morfología de las placas espumadas resultantes se analizó mediante Microscopía Electrónica de Barrido (MEB) y Tomografía Computerizada (CT), y las propiedades mecánicas fueron evaluadas a través de ensayos de tracción, flexión e impacto. El análisis morfológico reveló la e xistencia de una estructura piel maciza/núcleo espumado en las placas espumadas. Las propiedades mecánicas disminuyen gradualmente con la densidad aparente del material microespumado. La densidad aparence se reduce conforme el espesor de la placa, aunque l a rigidez a flexión aumenta considerablemente. L a nueva tecnología IQ Foam® permite la fabricación de piezas espumadas y ligeras con propiedades resultantes comparables a las obtenidas mediante MuCell ® , presentando otras ventajas en cuanto a coste, sencill ez e independencia de máquina inyectoraLightweight construction is one of the main strategies conducted by carmakers in order to reduce fue l consumption and greenhouse gas emissions. Since the demand of plastic and composite materials for automotive applications is continuously growing, lightening approaches like foaming techniques are b eing introduced with the aim of decreasing their weight. The present work aims to compare the morphology and mechanical properties of plastic foams obtained by two different foaming technologies: MuCell® and IQ Foam®. Solid and foamed plates of glass fiber reinforced - polypropylene (PP/GF) were injection molded by using MuCell® and IQ Foam® processes combined with the comple mentary tool technology Core Back expansion molding. The morphology analysis of the obtained plates was carried out through Scanning Electron Microscopy (SEM) and Computed Tomography (CT) techniques, and the mechanical properties were assessed by means of tensile, flexural and impact tests. The morphology analysis revealed the presence of solid skin - foamed core structure in the foamed samples. The mechanical properties decreased gradually with the apparent density of the microcellula r plates. By increasing the thickness of the part because of the expansion of the cavity, the apparent density decreased but the flexural stiffness was greatly enhanced. Foamed samples obtained by IQ Foam® technology exhibited lower cell density than that of the MuCell® ones, but consequently higher resistant area, and thus, slightly higher mechanical properties. The new IQ Foam® technology is able to produce foamed parts with properties comparable to that of the MuCell® process, offering additional benefits such as cost - effective ness, easy to use and machine - independencePostprint (published version

Influence of injection molding parameters on the morphology, mechanical and surface properties of ABS foams

In this work, microcellular ABS foams were studied. A series of injection molding samples defined by a design of experiments was carried out to analyze the effect of shot volume, mold temperature, and injection velocity on the morphology, mechanical properties, and surface roughness of microcellular samples. A predominant influence of shot volume on the cell structure and tensile properties was evidenced. Higher cell densities and narrower cell size distributions were obtained at lower injection volume. However, elastic modulus and tensile strength were improved by increasing the shot size. The effect of mold temperature and injection velocity was secondary. Higher levels of mold temperature and injection rate provided finer cell morphologies, but their effects on the elastic modulus and tensile strength were negligible. The decrease in shot volume and increase in gas content led to poor surface quality, whereas it was greatly improved by raising both mold temperature and injection velocit

Microcellular PP/GF composites: morphological, mechanical and fracture characterization

The aim of the present work is to analyze the morphology, mechanical properties and fracture behaviour of solid and foamed plates made of glass fiber-reinforced PP. The morphology exhibited a solid skin/foamed core structure, dependent on the foaming ratio. Simulation of the microcellular injection molding process with Moldex 3DR software provided a good approach to the experimental results. The flexural properties and impact resistance showed lower values as the apparent density decreased, but constant specific properties. The fracture characterization was carried out by determining the Crack Tip Opening Displacement (CTOD) at low strain rate, as well as the fracture toughness (KIc) at impact loading. Foamed specimens presented higher values of CTOD than the solid ones and higher as the foaming ratio increases, due to cells acting as crack arrestors by blunting the crack tip. However, the fracture toughness KIc decreased with decreasing the apparent density. Anisotropy due to fiber orientation was also observed. Fibers were aligned in the filling direction in the surface layers, while they were oriented in the transverse direction in the core. According to the amount of fibers oriented in one direction or another, different properties were obtaine

Microcellular injection moulding: a comparison between MuCell process and the novel micro-foaming technology IQ Foam

The present work aims to compare two different injection moulding foaming technologies, the already known MuCell® process and the new emerged technology IQ Foam®, as well as the cell structure and mechanical behavior of the obtained components. Glass fiber reinforced-polypropylene (>PP GF<) was employed to produce rectangular plates at solid and foamed conditions by using MuCell® and IQ Foam® processes combined with the complementary Core Back expansion molding technology, and the material structure as well as the tensile, flexural and impact properties were studied. A solid skin-foamed core structure was observed in the samples foamed by both techniques. The mechanical properties decreased gradually with the apparent density of the microcellular plates. By increasing the thickness of the part because of the expansion of the cavity with the Core Back technology, the apparent density decreased but the flexural stiffness was greatly enhanced. Foamed samples obtained by IQ Foam® technology exhibited thicker solid surface layers and lower cell density than that of the MuCell® ones, but consequently higher resistant area, and thus, slightly higher mechanical properties. The new IQ Foam® technology is able to produce foamed parts with properties comparable to that of the MuCell® process, offering additional benefits such as cost-effectiveness, easy to use and machine-independenc