The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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DEVELOPMENT OF MODIFIED POLYLACTIDE (PLA)
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.
EFFECT OF PHYSICAL AGING ON ENTHALPY RELAXATION AND EMBRITTLEMENT OF ELASTOMER THERMOPLASTIC BIODEGRADABLE POLY (L-LACTIDE/ ε-CAPROLACTONE)
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).
MECHANICAL PROPERTIES OF LACTIDE BASED SCAFFOLDS FILLED WITH INORGANIC BIOACTIVE PARTICLES
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.
DEVELOPMENT OF NANOSCALE INTERFACIAL MORPHOLOGY IN POLYMER-BASED NANO-CARBON HYBRID STRUCTURES FOR STRESS TRANSFER IMPROVEMENT
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.
REACTIVE EXTRUSION OF POLY(LACTIC ACID) WITH STYRENE-ACRYLICGLYCIDIL METHACRYLATE
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).
The Effect of Carbon Nanotubes on the Rheology and Electrical Resistivity of Polymer Blends
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.
THE EFFECTS OF COMBINING NANOCLAY AND STEEL WIRES MULTISCALAR REINFORCEMENTS ON THE STRUCTURE AND PROPERTIES OF POLYURETHANE FOAMS
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.
FIRE BEHAVIOUR OF FLAME-RETARDANT RIGID POLYPROPYLENE FOAMS
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 FREE DENTAL POLYMER COMPOSITES
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.
OPTIMUM FLOURPLAST: CREATING NEW OPPORTUNITIES FOR THE BIOPLASTIC INDUSTRY. PROCESS STRUCTURE PROPERTY RELATIONSHIPS OF A NOVEL BIOPLASTIC POLYMER COMPOUNDING SYSTEM
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 . 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.
New Processes for large scale automotive production of composite applications
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.
VISCOELASTIC CHARACTERIZATION OF SPORTS SURFACES AND ITS RELATION WITH FORCE REDUCTION MEASUREMENTS
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.
FUNDAMENTALS AND PRACTICE OF PLASTICS FAILURE ANALYSIS
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.
STRESS-INDUCED CRYSTALLIZATION OF A METALLOCENE HIGHDENSITY POLYETHYLENE
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.
SOLUTIONS WITH UV-CURING PAINT TECHNOLOGY FOR DIFFERENT BUSINESS UNITS
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.
COATINGS ON TRANSPARENT PLASTICS FOR AUTOMOTIVE APPLICATIONS
Transparent thermoplastic polymers hold an important position as materials for optics as well as for automotive glazing. However, soft plastic parts need to be protected by coatings. For optical applications especially antireflective coatings are inevitable. A presently wellestablished coating system for plastics is plasma ionassisted deposition. Special efforts are essential to find out the best coating conditions for each type of plastic. A comprehensive understanding of complex interactions between the plasma and the different polymer materials is a key factor for the development of coating strategies. Some coatings on polycarbonate for automotive applications will be discussed for example.
Surface Modification Techniques for Optimizing Adhesion to Automotive Plastics
Automotive plastics with a low polarity, such as PE, PP, TPO, POM, PUR and PTFE typically require surface treatment when decoration is required. Metallic surfaces may also require cleaning to remove low molecular weight organic materials prior to decoration. Once the above-mentioned interior and exterior grades of substrate surfaces are cleaned and activated, printing, gluing and painting are possible without the use of adhesion-promoting primers. This paper describes the latest innovations in three-dimensional surface treating technology for plastics finishing which address the need to advance adhesion properties, increase product quality, and achieve environmental objectives within the automotive industry. These innovations include advanced thermal and non-thermal discharge treatment processes for raising the polarity of surfaces to be painted, bonded, decorated, laminated, printed, or to have tape applied.
LIFETIME PREDICTION IN ENGINEERING PLASTICS - LIMITATIONS OF SHORT-TERM TEST EXTRAPOLATIONS
Using short term tests to predict future outcomes of any long term process is common in extrapolation techniques in Science, Social science and Engineering. However, in every process it is important to ascertain some sort of criterion before extrapolation techniques are employed. The criteria for predicting lifetime of an engineering plastics for the specific application must include the requirements of the test to (a) reproduce the mechanisms of field failures and (b) have a technically sound procedure for extrapolation of a the relatively short test data. We will finally propose a quantitative modeling approach as an alternative to “empirical” extrapolation.
Interlaminar Fracture Toughness Of Carbon Fabric Reinforced Epoxy Composites
The Mode I and Mode II fracture behaviour of three carbon-epoxy composite laminates with different fabric reinforcement and different matrices was investigated. Standard Double Cantilever Beam (DCB) and End Notched Flexure (ENF) delamination tests were performed to determine initiation toughness and to asses the subsequent crack propagation behaviour. Various toughening mechanism, acting at the microscopic level and responsible for the stick-slip propagation behaviour observed, have been identified. The effect of temperature in a range from -60° to 165 °C was investigated.
A COMPREHENSIVE STUDY OF LOW-DENSITY POLYETHYLENE IN CAPILLARY FLOW
The capillary flow of a commercial LDPE melt was studied both experimentally and numerically. The excess pressure drop due to entry (Bagley correction), the compressibility, the effect of pressure on viscosity and the possible slip effects on the capillary data analysis have been examined. Using a series of capillary dies having different diameters, D and length-to-diameter L/D ratios, a full rheological characterization has been carried out, and the experimental data have been fitted both with a viscous model (Carreau-Yasuda) and a viscoelastic one (K-BKZ/PSM model). Particular emphasis has been given on the pressure-dependence of viscosity, with a pressure-dependent coefficient βp. For the viscous model, the viscosity is a function of both temperature and pressure. For the viscoelastic K-BKZ model, the time-temperature shifting concept has been used for the non-isothermal calculations, while the time-pressure shifting concept has been used to shift the relaxation moduli for the pressure-dependence effect. It was found that only the viscoelastic simulations were capable of reproducing the experimental data well, while any viscous modeling always underestimates the pressures, especially at the higher apparent shear rates and L/D ratios.
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