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.
The effect of nucleation and quenching on the crystallization kinetics of PLA and its blend compositions were studied. Contrary to polypropylene, the nucleation effect of talc decreased rapidly as the cooling rate increased. The effect was enhanced as the talc content increased from 0.1 to 8%. The nucleation behavior is analyzed in light of a modified Kissinger method. The lack of nucleation upon quenching was shown in a modified Kissinger plot which showed its correlation with Avrami analysis. Methods to control or enhance crystallization of PLA and some PLA blends are discussed.
A novel simultaneous milling and coating method which utilizes a fluid energy mill (FEM) is applied for the first time to prepare nanoparticle-coated CaCO3 additives for polymer composite materials. Simply milled (without coating) CaCO3 particles and as-received CaCO3 particles were used as references for comparison. The effects of the grinding pressure and the content of the coating on the particle size and flowability of CaCO3 were studied. The composite made of PP and this specially prepared CaCO3 have larger elongation at break, elastic modulus and impact strength, compared to the simply milled calcium carbonate.
New family of ENH flame retardant PBT (polybutylene terephthalate) and PBT/PC(polycarbonate) thermoplastic resins developed is aimed at helping electrical/electronics (E/E) manufacturers and suppliers comply with regulations restricting use and disposal of hazardous substances. The non-chlorinated, non-brominated FR PBT and PBT/PC products deliver similar mechanical, physical, thermal and flame retardant performance compared with their brominated FR based counterparts. Some of those resin properties will be discussed in this publication.
In recent years, injection molding technologies have been developed which use variable mold heating and cooling to increase part quality without significantly increasing cycle time. These processes are not suited for simulation with a conventional steady-state (cycle-average) mold thermal analysis. This paper presents the development of a new 3D finite element based transient mold cooling simulation capability which includes coupling the mold thermal solution with the mold filling and packing simulation. The predicted transient mold temperatures are validated against measured mold temperatures for two instrumented injection molding trials.
The specific interfacial morphology and strength of paired polymers will be discussed. The focus is on two different types of interfaces during injection molding processes: (I) hot interface represents two melt streams meeting (weldline) and (II) cold interface is defined as the overmolding of a second melt to a chilled, hardened preform. A cold interface occurs during a multi-shots injection molding process. Regarding the strength amorphous and semicrystalline polymers were used, for the visual inspection of interfacial morphology by light microscopy semicrystalline POM was investigated. In conclusion, new aspects about a correlation between interfacial morphology and bonding strength are addressed.
This paper provides insights into a newly launched portfolio of environmentally progressive products. These molding compositions are based on a polybutylene terephthalate (PBT) that is made by chemical regeneration of post consumer recycle polyethylene terephthalate (PCR PET) and converted into PBT. These products can then be used in a variety of automotive and consumer applications. These new products' manufacturing processes require less energy and non-renewable fossil fuels as compared to the manufacturing processes of conventional fossil fuel based materials. We will present the comparison of properties results of molding compositions using this new technology and traditional PBT will be presented.
A novel method to synthesize polycarbonate-polydimethylsiloxane block copolymers with controlled block molecular weight and an alternating block architecture was investigated. The method investigated consisted of the synthesis of polycarbonate oligomers/polymers possessing allyl-functional endgroups and the subsequent coupling of the oligomers/polymers with hydride-terminated polydimethylsiloxane oligomers/polymers using hydrosilylation. GPC and NMR were used to demonstrate successful block copolymer formation. Characterization using AFM showed nanoscale phase separation. The optical clarity of a PC-PSiO block copolymer produced with this method was significantly better than that of a commercially available PC-PSiO block copolymer, indicating smaller PDMS domains resulting from the more uniform block copolymer structure.
Expanded polypropylene (EPP) bead foam products are prepared using the steam-chest molding method. It was shown that 3.9 bar is the most promising steam pressure to get better mechanical properties. The density and tensile property profile across the molded sample were measured. It was observed that the high pressure and temperature steam softens the beads on the surface causing them to squeeze and compact together. This leads to increase in the density and tensile property at the outer surface of the molded part as compared to the central part.
The temperature of an oven named OPT are evaluated. Two types of moulds, an aluminium ball-like and stainless steel cube-like, were used. Finite element software was used to find a combination of hot air flow velocity and the oven internal surface geometry. The temperatures obtained in the OPT were compared with temperatures obtained in Benchmark oven. For validation purposes the OPT was compared with simulations. The agreement between the OPT and the ROT time-temperature curve behaviour is remarkable. The OPT gas consumptions are compared with in an oven named here the Kearns found in the literature.
Atomic Force Microscopy (AFM) and infrared (IR) spectroscopy have been combined in a single instrument capable of producing sub-micron spatial resolution IR spectra and images. This new capability enables the spectroscopic characterization of microdomain-forming polymers at levels previously impossible. Films of poly(3-hydroxybutyrate-co-3-hydroxyheanoate) were solution cast on ZnSe prisms. Dramatic differences in the IR spectra are observed in the 1200-1300 cm-1 range as a function of position on a spatial scale of less than one micron. This spectral region is particularly sensitive to the polymer crystallinity, enabling the identification of crystalline and amorphous domains within a single spherulite of this copolymer.
Rheological properties of several polypropylene polymers were measured and the foam processing of these materials using chemical blowing agent was studied. Foaming was carried out in monolayer and skin-foam layer moldings. The uniaxial extensional viscosity was quantified and the foam characterized based on bulk density, bubble size, and bubble concentration. It was found that the foam processing window is determined and bounded by melt viscosity and melt elasticity. Melt strength and strain-hardening can substantially improve the foaming performance and play significant role in determining the developed morphological structure.
It was found that compression molded Wood Plastic Composites (WPC) show lower strength than the extruded WPC which could be due to lower net alignment of the reinforcing fibers and lower inter-diffusion and alignment of the polymer chains due to the smaller net flow of material during processing. To test this hypothesis, a new compression molding system was developed where materials were forced to flow in one direction. Comparative strength studies of WPC, prepared by this novel compression molding system, have been presented at varying speed and temperature of die-press. The initials results seem to validate our hypothesis.
Multi-walled carbon nanotube (MWNT) / high density polyethylene (HDPE) composites with varying amounts of carbon nanotubes were investigated and the effect of MWNT weight fraction on their electrical conductivity, crystallinity and mechanical properties is presented here. Samples were prepared by melt dilution of a HDPE masterbatch containing 20.2 wt% MWNT with varying amounts of neat HDPE. The effect of extrusion processing on the formation of an electrically conductive MWNT network in extruded samples was assessed by the addition of a low-shear annealing zone (shear rate 1-10 s-1) before final extrusion through a die and it is also discussed here.
Microcellular injection foam molding technology can bring a number of advantages to the existing conventional injection molded products such as lower density, material cost reduction, reduction of residual stress, better dimensional stability, reduction of cycle time, and better dispersion of fillers. However, the technology has not been fully employed yet, especially in the automotive sector, because injection foam molded parts, in general, experience a decrease in mechanical strengths. Therefore, this research studies the relationship between cellular and mechanical properties of the two common polymer composites in the automotive industry, which are glass-fiber reinforced plastics (GFRP) and wood-fiber polymer composites (WPC).
Polypropylene blends with thermoplastic starch (TPS) have demonstrated significant potential in the bioplastics field. The polymers are improved by achieving higher biocontent and lower green house gas emissions. The TPS is finely dispersed by means of a tandem extruder with plasticizer, water, heat, and shear, and then melt blended with the polymer to produce a co-continuous morphology of TPS and polymer. TPS blends produced in this method lead to improved retention of physical properties over conventional methods. The TPS method is presented as well as morphology, GHG emissions, and properties.
In this paper, highly crosslinked and vitamin E infused (VITE) ultra-high molecular weight polyethylene is evaluated for mechanical properties, oxidation resistance, and wear. Testing included small punch mechanical properties, impact strength, a fatigue study, and knee wear simulator testing. The VITE material showed no evidence of oxidation and no decrease in the mechanical properties with accelerated aging. The VITE material showed an 86% reduction in wear over the control. The combination of crosslinking and vitamin E infusion produced a polyethylene material with improved wear properties and superior oxidation resistance suitable for use in orthopedic applications.
In this study, a bio-based epoxy thermoset was made from highly functional epoxidized linseed oil (ELO) using a polyethyleneimine (PEI) crosslinking agent. Following optimization of cure conditions and the stoichiometric ratio of ELO to PEI, the compatibility of this system with several commercial montmorillonite and hydrotalcite layered nanofillers was studied. The hydrotalcites were observed to enhance the homogeneity of the ELO-PEI system, whereas the montmorillonites showed settling and produced inhomogeneous materials in all cases.
This study presents the application of Variational Asymptotical Method for Unit Cell Homogenization (VAMUCH) with a three-dimensional unit cell (UC) structure and finite element analysis for analyzing and predicting the effective elastic properties of microcellular injection molded plastics. A series of injection molded plastic samples with microcellular foamed structures were produced and their mechanical properties were compared with predicted values. The results show that for most material samples, the numerical prediction is in fairly good agreement with the experimental results, which suggests the applicability and reliability of VAMUCH in analyzing the mechanical properties of porous materials.
The purpose of this research is to understand the transient fiber orientation of long glass fiber (> 1mm) reinforced polypropylene, in a well-defined simple shear flow (using a sliding plate), by determining unambiguous model parameters from rheological experiments, and to ultimately predict fiber orientation in complex processing flows. Two fiber orientation models were investigated. One model, the Folgar-Tucker model, has been particularly useful for short glass fiber systems and was used in this paper to assess its performance with long glass fibers. A second fiber orientation model, one that accounts for the flexibility of long fibers, was also investigated.
The rheological properties of polypropylene filled with specially coated calcium carbonate were investigated in this study. CaCO3 fillers were coated in order to further improve the mechanical and flow properties of the filled polymer. A fluid energy mill (FEM) was used to simultaneously mill and coat the calcium carbonate particles. Both rotational and capillary rheometers were utilized to study the rheological impact of the coated particles. The rheological properties of the specially coated particles were compared with non-coated particles at similar concentration. Shear viscosity, dynamic viscosity and also melt flow index were determined at three different temperatures.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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