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.
Sticking of plastic webs to roll surfaces during film casting or sheet calendaring may cause aesthetic defects as well as rate limitations. This study was undertaken to gain an understanding of the relative contributions of polymer density, crystallinity, and molecular weight to roll sticking. A design of experiments using ethylene-octene elastomers showed that the density of the polymer, and hence the crystallization temperature, had the most significant effect on the roll sticking performance. Within the range of polymers studied, the molecular weight did not have a significant contribution to the roll sticking. It was also shown that physical properties could be predicted by the combination of Mn and density.
In the mold design process the electrode is designed in advance for a contour requiring high accuracy or for a complex contour. The mold material, fixture specification, and the working ability of electrical discharge machine are all considered in the design process; otherwise, there will be inaccurate positioning and poor machining accuracy. Therefore, to increase mold machining accuracy, the information of design and manufacturing stages must be integrated in order to prevent the design and manufacturing planning stages from mistakes, to solve problems, and to transfer information to the manufacturing stage effectively. In this study the redevelopment of the navigation process for electrode design of electrical discharge machining (EDM) is based on a computer-aided design (CAD) software, under the concept of design for manufacturing (DFM). The regions requiring EDM are listed for the engineer by using the feature recognition method according to the feature specifications. The machine working ability and material information integrated in the process can guarantee the manufacturability of electrode design, reduce the error rate of electrode design, and shorten the design time by over 70%.
In this paper, Biodegradable poly (3-hydroxybutyrate-co- 3-hydroxyvalerate) (PHBV)/polylactic acid (PLA) biocomposites were prepared using the Hakker rheometer. We investigated the effect of various PLA content on the PHBV’s thermal properties and on its foaming behavior. The differential scanning calorimetry (DSC) results showed that the presence of PLA facilitate the cold crystallization of PHBV matrix. Along with the addition of PLA, the melt temperature of composites are lower than pure PHBV. SEM results of foamed samples presented that the addition of PLA led to the various foaming morphologies, and cell morphologies was changed from close cell to open cell as increasing the content of PLA in the PHBV matrix. The changed foaming morphology was attributed to the phase morphology and composites melt strength changed, and the resultant mechanism was also proposed.
This paper presents a method to prepare kinetically trapped composite foams using anisotropic semicrystalline media as a template. The semi-crystalline polymer templates used were films (Polyethylene Terephthalate) and filaments (Polyamide-12) which are biaxially and uniaxially oriented respectively. Supercritical carbon dioxide was used as a solvent to transport styrene monomer mixed with a radical initiator into the template. This phase was allowed to polymerize and foam to create a microcellular structure. Even though template anisotropy did not dictate the final morphology of the cells, interesting cell structures such as radial gradient and biaxial were observed due to the processing conditions. Initial mechanical tests showed an improvement in specific modulus and specific strength. This approach might be useful to create composite foams with tunable macroscopic and microscopic features that could be potentially used as a replacement for Balsa wood.
Two different form of polyamide 6 (PA6), granule and powder, was employed to produce the immiscible PA6/polypropylene (PP) blend (50/50 by wt.%) composites filled with prestine single-walled carbon nanotube (SWNTs) contents of 2 wt.%. The effect of different physical form of PA6 on the selective localization of SWNTs was studied by measuring the morphological, rheological properties and thermal conductivity. The images of Scanning Electron Microscopy (SEM) confirmed that SWNTs were selectively located in PA6 phase, which is in good agreement with the results of wettability coefficient calculation. Due to pre-interaction between powdered PA6 and SWNTs, PA6 phase was shown as discontinue-like morphology compared to that of composite using granule PA6. For this reason, the capable volume, where SWNTs is selectively located, and its network is formed, is more confined in the composite, leading the lower storage, loss modulus and complex viscosity at low frequency region. The thermal conductivity of powdered PA6 contained composite had about 10% higher than that of granule PA6 contained composite. This is probably because at the same loading, the effective volume concentration of the tubes in the PA6 phase of composite prepared by powdered PA6 is higher than that of composite prepared by granule PA6.
Powered by a new leading-edge catalyst technology, DOWLEX™ GM Linear Low Density Polyethylene Resins (LLDPE) offer Greater Means for customers to achieve differentiated performance and new growth opportunities for a range of demanding film applications. Applications discussed are those primarily in the industrial and consumer packaging applications of consumer liners, collation shrink film, heavy duty shipping sacks, and cast and blown stretch film.
This paper investigates the effect of microwave application for the drying of pellets for five different polymers. As microwaves stimulate water molecules directly, they can be used for a volumetric heating of the pellets and increase the speed of migration of moisture from within the pellet to its surface. Experimental results show how microwaves lead to a temperature invariant drying speed, at least above a polymer specific threshold temperature. Comparisons with a reference dryer showed an increased drying speed through microwaves at lower drying temperatures, but not necessarily at higher ones. However, taking into account constructive inefficiencies of the prototype microwave dryer, microwave application shows the potential to significantly reduce drying times also at higher temperatures, which is shown representatively for polyamide 6. An analysis of material properties after drying did not show significant differences between microwave drying and conventional drying.
During melt processable compounding of an optical material with a high filler loading, there can be concerns with filler incorporation and distribution. To address these problems, compatibilizers may be used, however they must not affect the refractive index (RI) match of the two materials or there will be a loss in optical properties. In this work, two compatibilizer systems (C1 and C2) were compared for improved calcium fluoride (CaF2) loading into three different RI matched systems: a refractive index liquid, a two-part silicone, and poly-4-methyl pentene (PMP). The C2 treated filler also was treated with mineral oil and used in PMP. Compatibilizer C1 showed larger agglomerates than the untreated filler, as well as a significant reduction in light transmission in both the RI liquid and silicone systems. Compatibilizer C2 exhibited improved dispersion of the filler and had similar light transmission behavior as the untreated filler in the RI liquid and silicone systems. When compounded with PMP, compatibilizer C2 helped to increase the loading level achieved in the process by 5%, while the C2 and mineral oil treated material significantly improved the loading level (by 33%). The mineral oil also improved the flexibility of the final product.
In this paper, tensile properties of homo polypropylene (PP) with respect to talc filler content were predicted using regression model and neural network model. Talc content, tensile speed, Differential Scanning Calorimeter (DSC), Gel Permeation Chromatography (GPC) and rheometer data were used as modeling input factors. 2 different multiple regression models and 1 neural network model were established and the models were compared quantitatively by average error rate (AER). The results showed high reliability for all models but neural network models were determined as the most meaningful model.
This paper describes an innovative through-thickness fiber reinforcement technology for laminate structures by using shrinking microfibers. Unlike incumbent passive fiber reinforcing technology, in-situ shrinking microfibers that respond to an external stimulus such as heat can induce pre-compression to matrix and create additional resistance from external loads. In this paper, Heat-Activated Shrinking (HAS) microfibers and Heat Passive (HP) microfibers made were used to investigate the interlaminar reinforcing effect of fiber shrinking mechanism. The specimens were reinforced by three different fiber geometries: (i) 1.27 cm (0.5 in) interval stitch of single microfibers, (ii) 2.54 cm (1 in) interval stitch of single microfibers, (iii) 2.54 cm (1 in) interval stitch of double microfibers, and then peel strengths were compared with control using T-peel tests. For Case (i), the reinforcing effect from HAS microfibers was shown by 47.2 % improvement compared to the specimens with HP microfibers. By comparing to control specimens, it was almost 2,883% improvement. For Cases (ii) and (iii), 27.7 % and 57.0 % increases in peel strengths were resulted respectively. Comparing the control specimens and the specimens with HAS microfiber, it was 2,191% and 3,741% improvements, respectively.
Theory of single screw extruders has been used for analyzing the processing characteristics of various polymeric fabricated such material as plastics, rubber, and food products. This theory can be extended to measuring the polymer melt viscosity using the closed discharging state of the short single screw extruder. The batch wise operation of the closed discharged state changes the complex extrusion characteristic equation into simple calculation form of shear rate and viscosity equation. Using the screw rheometer for various polymer melt systems have many advantage for easiness of operation, good reproducibility, short time for measuring for pure polymer, measurement for the blowing agent laden polymer systems has the advantage of using the same processing equipment.
The largest field of application for plastics is currently packaging  as they offer good mechanical properties combined with low density. A drawback of plastic packaging for food, pharmaceuticals and electronics applications over e.g. metals or glass is often their permeability to oxygen, carbon dioxide, water vapor and aroma. In order to improve this property, nano-scaled plasma-barrier coatings are researched [2, 3]. These are able to form a thin, virtually impermeable layer on the substrate and then improve the permeation properties. In this work the influence of stacking and the temperature dependency of the oxygen transport through thin PE-CVD coatings on polypropylene is investigated.
A methodology is introduced in this work to investigate the anisotropic elasticity constants of a short carbon-fiber-reinforced ABS plastic based on an orthotropic material model for FDM structures. Special unidirectional tensile specimens, which exhibit a specific building-space and individual-layer orientation, are produced for this purpose on a MakerBot Replicator 2X FDM system. The consistent approach to material characterization enabled a complete, validated material-data set for unidirectional FDM structures to be generated for the first time for a short fiber-reinforced plastic. This can be used directly for numerical calculations and optimizations of complex FDM structures in the linear elastic range for instance to develop lightweight structures that are specially adapted to the possibilities of a FDM process.
Combined birefringence-tensile testing was used to characterize stress development in medical-grade polycarbonate (PC) of four specimen geometries, which included un-notched samples and notched samples with various radii of curvature. Finite Element Analysis (FEA) was also performed to characterize the same geometries. The experimental birefringence stress maps of standard and notched tensile specimens were shown to correlate very well to contour stress maps generated from Finite Element Analysis (FEA) for the same geometries. Depending on the radius of curvature of the notch, the stress maps exhibited slightly different patterns; with sharper notches there were much higher local stress concentrations, which led to yielding and failure at lower displacements. This investigation shows the potential for combining birefringence analysis with mechanical testing, especially when inspecting parts, evaluating residual stress, performing screening studies of stresses, or for comparison to FEA results.
A new way of rapidly sorting packaging into high purity streams (> 99%) has been developed based on intelligent labels with invisible markers that can be detected and sorted using existing high-speed optical sorting systems used in MRFs with minor modifications. The principles have been proven using a range of commercially available UV responsive fluorescent markers with high emission yields. A full-scale commercial optical sorting trial was conducted at the MRF facilities of Tomra in Germany. Sorting of used plastic packaging for closed loop recycling back into food packaging requires positive identification and sorting of the recycled materials to a higher standard. The operators of commercial food grade recycling processes are required to demonstrate the recycled materials meet relevant European Food Safety Authority (EFSA) criteria; these require at least 95% (PET) and 99% (HDPE) of the feed material must have been used for food contact in their first life. The initiation of closed loop food grade recycling of PP packaging is awaiting a viable technical solution to differentiate the food grade packaging. From previous sorting trials, it can be estimated that of the 143,000 tons of PP food packaging used annually , 77,077 tons could be recovered each year in the UK. The objective of this project was to further develop the fluorescent marker technology investigated in earlier projects that has the potential to meet EFSA requirements and to extend the scope to different applications, enabling and facilitating the sorting of different polymers to a high degree of purity. The scope of the project included the optimisation of fluorescent compounds, evaluation of their stability in the supply chain and the ability of the compounds to be effectively removed during the cleaning and decontamination process. The project investigated the viability of the technology and its capacity to be implemented in the UK and elsewhere. Unlike existing NIR sorting systems , this technology uses commercial labeling and decoration methods to sort targeted streams potentially including food-contact plastics, bioplastics, chemical packaging, automotive plastics, black plastics and different grades of one plastic. This technique has the potential to create new recycling loops for food grade PP, milk bottle sorting and PET products. The project demonstrated that the use of commercial labels incorporating fluorescent markers can be used to sort plastic bottles and packaging with high yields and purity.
A new approach employing carbon nanostructure (CNS) buckypapers (BP) to prepare glass fiber/epoxy composite laminates with enhanced resistance to delamination and damage monitoring capability is presented. Selective reinforcement in composite laminates was achieved by introducing the CNS-BS at the interlaminar region more prone to delamination. CNS wetting by the epoxy was improved using plasma treatment to promote stronger interfacial bonding. A significant increase in interlaminar fracture toughness in mode I and II was observed in composite laminates with CNS-BP at the laminate midplane. Cohesive/adhesive fracture of the conductive CNS layer enabled damage monitoring by electrical resistance measurements upon delamination. The proposed method using multifunctional ply interphases allows coupling damage monitoring with interlaminar reinforcement in composite laminates.
Luxury Vinyl Tiles (LVT) are the largest growing product group in vinyl flooring. The high-quality appearance combined with the ease of installation and maintenance results in a steadily growing demand. As more and more companies are entering the market, a broad variety of processing options evolved. The compounding processes are required to deal with higher line speeds on one side and higher expectations concerning process flexibility and higher economical pressure on the other side. In the last years, more and more Continuous Kneaders are applied in this application. The unique principle of operation is used for all the different layers of the LVT. In the course of this talk we will investigate different options (with a focus on pelletizing and calendering processes) to deal with the demands of the market. New developments concerning the addition of fillers into the compounding process applying Continuous Kneaders are investigated and compared to standard solutions. A significant increase of the line productivity can be achieved applying the newly developed intake system while keeping the screw speed of the Kneader screw at a very low level.
Linear isotactic polypropylene (PP) is used in a vast array of applications because it provides mechanical strength, chemical resistance, and thermal stability. However, semi-crystalline linear PP has limited use in low-density foam applications, which are dominated by amorphous polymers, such as polystyrene. This paper discusses technical challenges that have limited the use of PP in low-density, extruded foams. Specifically, the challenge of controlling foam density along with closed cell percent and cell count is addressed. The rheological properties have been evaluated in terms of viscosity, elasticity and melt strength which show good foaming potential. Interactions between the HMSPP polymer, linear PP blend polymers, blowing agent type, additive formulation, and process variables are investigated here for a new, developmental HMSPP grade. Braskem has developed a proprietary technology to produce High Melt Strength Polypropylene (HMSPP), branded as the Amppleo family, with a specific long chain branching configuration that helps overcome the limitations of linear PP when foaming to low densities of 150-50kg/m3.
The subject of this publication is the detection of optimization potential and the avoidance of faults and errors in the injection molding process using process data analysis. In modern injection molding machines, in addition to the produced plastic moldings, high amounts of process and machine data are available – in very high quality. Injection molding machines are equipped with high-resolution measuring devices that are connected to the bus system of the machine, which reaches out to all the components from the plasticizing barrel, frequency converters for drives, mold cavities, etc. To date, however, these data have not been fully exploited and have not been accessible in a convenient way. Through the further development of bus-based data interfaces, it is now possible to obtain all signals and sensor data, and use these data for external analysis purposes. The decisive factor is central recording of the relevant signals with a uniform time base. Corresponding recording in real-time facilitates complete documentation and utilization of the relevant process and machine data. Subsequently, these raw data must be processed appropriately so that they can be used for analysis purposes in order to extract the information from process and production, and generate corresponding benefits for the users and operators. Firstly, strategies and methods are shown on how (raw) data from a machine control (PLC) can be extracted and made available to the operator. For a diagnostically conclusive analysis, the complexity and the size of the data must be significantly reduced – here, machine and process-specific key figures are generated. Key figures are combined with one another and further compacted so that additional information can be obtained more easily.
This study investigates the effects of extruder temperature and screw speed on the thermal properties of glass fiber reinforced polyamide 6 (PA6) composites throughout the direct long-fiber reinforced thermoplastic (D-LFT) process. Thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) analyses were performed on samples taken from different locations along the D-LFT process. TGA results showed that the low screw speed of the extruders increased apparent activation energy of the final product. Non-isothermal DSC crystallization analysis revealed no substantial changes to the material’s degree of crystallinity with the variations in extruder temperature and screw speed; however, isothermal DSC crystallization analysis showed that the low screw speed of the extruders increased crystallization half-time of the final product.
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