SPE Library

By the year 2025, carbon emissions levels will require for the main vehicle in the world important weight reductions. Plastics components can now be expanded during injection keeping correct mechanical behavior to design vehicle interiors. The paper presents the instrument panel application and describes the importance of the Polypropylene (PP) material, the expansion technology and the related component, injection press and tooling designs. The paper aims to demonstrate how applications like visible instrument topper panels or side trimmings could be designed in purpose to respect esthetical and mechanical specifications

Foaming of polypropylene is not trivial due to its weak melt strength and its semicristalline character. The solutions proposed up to now are based in crosslinking the polymeric matrix or in the use of special polypropylene grades. A collection of samples with relative densities in the range of 0.3-0.6 have been produced using a conventional PP grade. The improved compression moulding foaming process which uses a chemical blowing agent was used to produce the analyzed foams. The effect of chemical composition on both cellular and mechanical properties has been analyzed.

In this work, a hybrid polypropylene (PP)/steel car part (Traverse leg) was created by over moulding. PP was modified with 10%wt. of PP-g-Ma coupling agent. Different surface treatments were applied to the steel determining its influence on adhesion. Best peel strength was reached when the steel was sanded. Etching and shot peened plates showed similar but lower levels of adhesion. In all cases, the application of torch heating was necessary to create a thin layer of iron oxide strongly bonded to the steel and by reaction to the PP-g-Ma. To create adhesion a minimum steel temperature of 120ºC was necessary.

Created from University of Zaragoza, the group T.I.I.P. has developed its activities since 1989 around injection molding. This team has always worked as near as possible to the industry (its name includes “workshop”, not “laboratory") and, in its aims, it promotes the research work pushed from market demands. However, for an effective knowledge exchange, the members of the group T.I.I.P. have promoted hundreds of training courses teaching to all the injection´s actors, about how to arrange the whole process to improve final results. During these twenty years, fifteen doctoral theses and twenty friendly computer programs for training were made, closing the loop.

A new type of materials has been produced by means of creating a cellular structure in blends of LDPE/LLDPEg- MAH/ATH. The presence of the aluminium hydroxide (ATH) in a polymer blend, both as flame retardant and reinforcement, significantly increases the density of the end product. The aim of this work is to achieve a cellular structure by foaming these materials, when high loading levels up to 60wt% of ATH are included. As a result, a density reduction of 50% has been obtained together with excellent mechanical and flame retardant properties. A comparison of these properties between solid and foamed materials is included.

Polylactide (PLA) and other bio-based plastics have been attracting much attention for environment problems. In this report, modified PLA resin have been developed and based on “Technology of Nano-Modification for Polymer”, such as control of softening and of crystallization in nano size. Two types of modified PLA of which one is clear and soft PLA for extrusion molding and another one is high moldability PLA for injection molding have been developed. These modified PLA have been applied as alternative plastics of PP and ABS to stationery, packaging, convenience goods, electrical appliance and so on. Performances and technologies will be presented.

In the design of new polymeric materials the longterm stability and durability are matters of considerable importance. It is known that during physical aging volume contraction and densification of polymers occur and therefore physical properties such as mechanical or crystallization behavior of amorphous polymers may be affected. In this work the impact that physical aging has on two biodegradable poly(L-lactide/ε-caprolactone) (PLCL) copolymers differing on their randomness character was studied. Their thermal behavior has been evaluated by specific aging strategies using Differential Scanning Calorimetry (DSC).

The mechanical properties of highly porous scaffolds have been investigated. Scaffolds of poly(Llactide)( PLLA) and poly(L-lactide/ε-caprolactone)(PLCL) filled with 5, 10 and 15 vol.% of Bioglass® (BG) and hydroxyapatite (HA) particles were prepared by a solvent casting/particulate leaching procedure. The thermal properties of the scaffolds were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), while the morphology was characterized by scanning electron microscopy (SEM). All scaffolds presented a highly porous structure (≈90% porosity) and well-interconnected pores. Tensile test results revealed that the addition of bioactive particles increases the modulus and decreases the relative elongation at break.

Composites based on carbonaceous materials and polymers have been researched since the production of carbon fibers in the 1960s, leading to disruptive technological changes in the field of materials science. Today micro- and nano-scale carbon materials have opened new directions within this field to produce composites for high-performance applications. This work outlines in-situ analysis of the POLYMER-NANO interfacial zones in the composite as a function of nano-carbon structures. Stress transfer analysis of the composite interface couples nano-carbon structure with morphology and mechanical performance. This work addresses fundamental issues for materials design toward commercialization of polymer-based nano-composites meant for high-performance technologies.

In this paper are discussed the rheological changes observed in PLA by one-step reactive extrusioncalandering (REX) using as a chain extender (CE) an oligomeric copolymer styrene-acrylic multifunctional expoxide. Dymamic rheological experiments and gel permeation chromatography tests were used to characterize the architectural modifications of two grades of PLA, with different D-enantiomer content. According to the results, an increase on D-enantiomer content seems to reduce the CE coupling reactions. At the extrusion conditions used high level of chain modification is obtained as could be revealed by the increase on low frequency complex viscosity as well as in the storage modulus (G’) (associated to the melt elasticity).

Different mixing protocols were used to incorporate Carbon Nanotubes (CNT) into Polyamide 12 (PA)/ High Density Polyethylene (PE) blends. At a composition of 75PA/25PE/0.75wt.% CNT, interface localization of CNT promoted by predispersing CNT in the PE phase, resulted in five decades lower resistivty compared to other mixing protocols. Melt storgae modulus (G’) was also found to be affected by interface localization in this case with over 20% higher G’ compared to the other protocols. Specific CNT localization is explained in terms of preferential interaction between PA and CNT on the one hand, and kinetic restrictions arrising from the mixing protocol on the other.

In this paper we prepared and characterized several polyurethane composite foams by combining variable concentrations of organophilic clay (montmorillonite) and metal reinforcement, with the objective of developing novel multi-scalar multifunctional rigid foams. The addition of montmorillonite clay promoted foaming and the formation of finer and more homogeneous cellular structures, resulting in foams with compressive elastic moduli and collapse stresses lower than that of the unfilled polyurethane foams. However, a comparative analysis versus the foams’ relative density demonstrated that both mechanical properties follow one single trend for the two materials. The combination of montmorillonite and metal reinforcement further reduced the cell size of foams, ultimately resulting in foams with similar mechanical properties for considerably lower relative densities. Although no important differences in thermal conductivity were found for the polyurethane foams with adding montmorillonite, the incorporation of the metal reinforcement led to considerably higher thermal conductivities, its value increasing with increasing relative density.

It is well known the growing industry interest in reducing the high flammability of polymers, as it limits their suitability in a wide variety of applications where fire retardancy is required, at the same time maintaining some of the advantages related to their lightness. With that in mind, this work presents the development of new rigid polypropylene composite foams filled with high amounts of flame-retardant systems based on hydrated magnesium carbonate. Particularly, interesting flameretardancy synergistic effects were observed in the polypropylene composite foams by means of cone calorimetry by combining the hydrated magnesium carbonate with an intumescent formulation and layered nanoparticles.

Bisphenol-A (BPA) is suspected to be an endocrine disrupter. Current polymeric dental materials are based on BPA derivatives, e.g. Bisphenol-A Diglycidylether Methacrylate (Bis-GMA) which may leach out unreacted monomers and its degradation products. Consequently, the present work deals with BPA-free alternatives, for potential use in dental polymers and composites. Experimental results indicated that BPA-free monomers from natural and synthetic sources can replace Bis - GMA without sacrificing physical and mechanical properties of the final dental polymeric adhesives and composites.

This paper describes an outline of the structural features (using SEM, WAXS and other advances techniques) and various properties of products containing compatibilised thermoplastic flour (i.e. Optimum FlourPlast). Grain or cereal flour or even purified starches are them self not thermoplastic materials [1]. The thermoplastic flour (TPF) is made from an unique combination of natural based grain (by-) products and a novel compatibilising polymer system making it a thermoplastic material, which can be processed on standard plastic processing machines. The TPF is as such shown to be highly compatible with natural or petrochemical based biodegradable aliphatic (co-) polyesters and various polyolefins such as polypropylene. In such combinations it is shown that it improves processing conditions and enhances the properties of the end formulation (compounds). By making different combinations of the various grades of the TPF (i.e. building block system of precompounds) with other polymers it will be shown that it is possible to obtain a range of products with different properties and good functionality. This made it possible to process the components into products suitable for various applications such as injection molding, extrusion and thermoforming, and film blowing and casting.

In conventional manufacturing processes, composite structures are formed in multistage, costly process chains and joined in additional process steps (e.g. gluing or welding). In terms of process engineering, the biggest savings in mass production can be achieved by minimizing cycle time. Jacob has developed new processes, FIT Hybrid (JEC Award 2011) and SpriForm which combine molding, forming and joining processes of thermoplastic composites in a single, cost-effective, large scale process. The key benefit of the invention is that, in addition to the lightweight potential of composites, this process offers the extraordinary potential of lightweight construction due to the combination with structural design.

The present paper describes the activity carried out to investigate the dependence of the force reduction measure of sport surfaces on the material’s viscoelastic dynamic properties and on the geometry of the sample. The study was carried out by means of lab tests with an artificial athlete apparatus and by dynamic-mechanical analysis. Seven different sport surfaces were tested with the artificial athlete and their viscoelastic properties analyzed. Other polymeric materials were studied besides the sport surfaces, in order to explore a wider range of properties. The results show a marked effect of sample thickness on the force reduction measure, and a method to correlate them with intrinsic properties of the material is proposed.

It usually comes as a surprise when a plastic product fails. Plastics are made to succeed, not to fail. Sometimes the financial liability can be high, such as a waterline break that is not detected and causes major property damage. If there is a fatality due to plastics failure, criminal charges may be brought. A company can be forced into bankruptcy by plastics failure. So answering the question "why do some plastics fail and others don't" is of major importance. The answer involves choices of material (chemical composition, molecular weight and intermolecular order), design, processing and service conditions.

The final mechanical properties of a plastic product which is made of semi-crystalline polymers depend significantly on the molecular properties and the applied processing conditions. Particularly, the formation of flow induced structures via polymer crystallization plays a major role in defining the final attributes of the product. In this paper, the effects of shearing, uniaxial extension and temperature on the flow induced crystallization of a high-density polyethylene (HDPE) are examined using rheometry. Extensional flow found to be a stronger stimulus for polymer crystallization compared with that of simple shear. Generally, strain and strain rate found to enhance crystallization in both simple shear and elongation at temperatures around the meting point. At temperatures well above the melting point, polymer crystallized under elongational flow while there was no crystallization under simple shear flows.

UV-curing paint technology is known since many years e.g. in the field of wood application or in the area of plates and blanks. Today it is also getting more and more common for automotive and decorative applications starting with new improved technologies also to paint 3- D parts. The new Dual-cure paint system of PETER-LACKE combines the advantages of the very fast drying and excellent scratch resistance of a UV-curing paint system with the 3-D painting ability and physical properties of a conventional thermal cured PU-paint system. A dual-cure piano black system was launched e.g. for the new Audi A8 Interior. The UV-Mono-cure systems – just cured by UV-light – give additional to the very short cure time of just a few seconds the advantage of very low or no emissions. Many colours and effects are possible in both UV paint systems and can be used on various plastics as well as on metal or glass.