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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Long Fiber Reinforced Thermoplastic (LFRT) materials offer superior impact strength and stiffness compared to raditional short fiber reinforced materials. For several decades these specialized compounds have grown in volume and diversity. Initially introduced as LFT (Long Fiber Thermoplastic) pellets the compounds have evolved into D-LFT (Direct Long Fiber Thermoplastics) variants and expanded their process capability to include injection compression and transfer molding.
The use of natural fiber composites is increasing in the automotive industry as well as in other industries. One of the key design issues in many of the applications for which natural fiber composites are considered is the stiffness. In this study we consider combining a natural fiber/polypropylene composite with either directional polypropylene or carbon fibers with the objective of improving the stiffness. Compression molded plates were prepared with various combinations of these materials. Tensile and flexural moduli of the combined materials were determined and are reported in this paper.
Natural fibers from agricultural activities have been emerged as alternative fillers in the thermoplastic industry. Crops such as wheat straw are renewable and low cost materials that combined with thermoplastics such as polypropylene provide engineering products with unique characteristics. Due to the wide range of thermoplastics and potential agricultural fillers the influence of additives in the systems is one of the points yet to be determined for different combinations of matrix and filler. In this study composites containing 30 wt-% of wheat straw (WS) fibers and polypropylene (PP) were prepared in a batch mixer. The individual effects of two coupling agents and a lubricant in the composites were investigated. Scanning electron microscopy (SEM) was used to examine the morphology of wheat straw particles and composites. The water absorption behavior and mechanical properties were assessed for those composites prepared. Results showed a strong interaction between filler and matrix in compositions containing coupling agent; differences were observed in the performance of the two coupling agents tested. Furthermore the lubricant used contributed to the water absorption of the composites.
Natural fiber composites or biocomposites have recently gained much attention due to their low cost environmental friendliness and their potential to compete with glass-fiber composites. However the use of all-natural resins is limited due to performance concern and hence the blending bio-resins in petroleum resins has gained importance due to their improved toughness and environmental friendliness. Nevertheless addition of bio-resins generally compromises stiffness barrier and thermal properties. The enhancement of polymer stiffness and barrier properties with small concentrations of layered silicates is well established. With this context the paper presents the development and thermo-physical characterization of a hybrid composite material with increased environmental friendliness that can retain stiffness without sacrificing toughness barrier and thermal properties. Hybrid biocomposites were made from bio-based resins (blends of unsaturated polyester and epoxidized soya bean oil) reinforced with organo-nanoclays and natural fibers (unprocessed industrial hemp). Results show that an optimum material design that maximizes the synergy of the constituents is possible and provide an initial benchmark in identifying such balance.
Long glass fibre thermoplastics (LGFT) used in compression moulded applications has grown dramatically due to metal replacement by composites and the derived benefits in both cost and weight savings. In order to make thin walled parts from higher viscosity thermoplastic materials as opposed to thermosetting resins machine producers have been challenged in terms of clamp size and tooling. In this paper a revolutionary new process called differentiated compression moulding (DCM) is described and compared with traditional compression moulding. Using new tool designs the process allows for reductions in press sizes of up to 70%. This in turn allows for significant cost savings in machine investment tooling and energy consumption. Larger projected areas and thinner walled investment tooling and energy consumption. Larger projected areas and thinner walled parts can be made on smaller machines. The paper discusses the physics and rheological conditions that allow for this innovation and a test case is compared to current technology.
The Automotive Composites Consortium Joining Working Group (ACCJWG) teamed with Visuol Technologies and EOS Technologies to develop a measurement system for quantifying the severity of “bond-line read-through” (BLRT). BLRT is a visual defect that can occur when two panels are bonded together. The measurement system is based on the ONDULO technology developed by Visuol Technologies. To develop the metric the ACCJWG provided Visuol Technologies a set of forty-eight panels with varying amounts of BLRT. Curvature maps for each of the panels were captured using the ONDULO technology. Visuol Technologies then used the in formation in the curvature maps to develop an algorithm for calculating a BLRT “score” that quantifies the severity of the defect. The algorithm first filters out any pixels in the curvature map below a certain magnitude. The remaining pixels are grouped by their proximity to one another to create discrete defects. Since there were many small defects found in the curvature maps a defect?s mean amplitude and aspect ratio are required to fall within certain thresholds to be included in the final score. The score for each individual defect is the product of its mean amplitude size and aspect ratio. The final BLRT score for a panel is a sum of the scores for each defect on the surface. Since the original algorithm was developed using panels made with continuous beads of adhesive the algorithm is being modified to properly assess other types of defects. For the set of panels used to develop the initial algorithm the score developed was shown to correlate well to the visual assessment of the panels. Furthermore since the metric is based on measured physical characteristics of the defects it provides a
unique method for objectively quantifying the severity of BLRT defects.
Automotive applications of compression molded products with a thermoplastic matrix have been growing rapidly within the last few years as demonstrated by increased use in applications including front-ends bumper beams dashboards and under body shields. Long fiber thermoplastics (LFTs) have received much attention due to their processability by conventional technologies. However applications of LFT materials have been limited in external body parts that require a good surface finish. Painting LFT parts is rare and requires considerable equipment investment. Further painting is often associated with environmental concerns such as Volatile Organic Compounds (VOCs) and high energy consumption. This paper innovates the process of extrusion compression molding for long fiber thermoplastic parts by placing a film (with a thermoplastic olefin backing) in-mold that melt bonds to the LFT material. This results in a compression molded LFT part that has the nice surface finish required for exterior applications. In order to evaluate the process variables potentially contributing to the surface quality are identified and analyzed. A Design of Experiments is carried out to investigate thoroughly yet
economically the effect of four process variables. Gloss chip resistance and adhesion of film to substrate are tested according to ASTM standards. These test results are used to evaluate the effect of the processing variables considered and to establish optimum operating parameters.
With the goal of weight and cost reduction in the automotive industry the need for a technology able to produce highly structural composite parts in a short cycle time is very important. That's why RocTool adapted its Tool Surf
ace Heating Technology to the RTM process. The inductive phenomena allows this technology to heat fast and cool down quickly the tool surface leading to many advantages for the RTM process such as : overall cycle time
reduction filling time reduction and safer filling of the mould injection time reduction warpage reduction because of extraction of cold parts surface quality improvement.
Recent research at Michigan State University has shown that it is possible to exfoliate natural graphite into platelets having thicknesses of less than 10nm and diameters of any size from sub-micron to 15 microns or greater. Since graphite is one of the stiffest materials found in nature (Young’s Modulus = 1060 GPa) having a modulus several times that of clay and also has excellent electrical and thermal conductivity the addition of these nanographite platelets to polymers can impart a combination of desirable mechanical electrical thermal and barrier properties to the resulting nanocomposite. We have investigated the addition of exfoliated graphite nanoplatelets (xGnP) to a vinyl ester resin to achieve a nanocomposite with an optimum combination of conductivity and mechanical properties. It was found that the flexural modulus increased with increasing the content of xGnP regardless of the dimensions of the particle. The flexural strength decreased with increases in the content of xGnP dependent on the size of xGnP. The impact strength of the nanocomposite reinforced with xGnP having a diameter about 1 micron (xGnP-1) increased compared to the nanocomposite reinforced with xGnP-15. The electrical impedance (resistivity) of the xGnP reinforced vinyl ester nanocomposite and particularly the percolation threshold depended strongly on the size of xGnP. The nanocomposite reinforced with xGnP-1 has a higher percolation threshold and resistivity compared to the one reinforced with xGnP-15. It will be shown that by blending xGnP-1 and xGnP-15 it is possible to obtain a combination of good mechanical properties as well as resistivity
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
Available: www.4spe.org.
Note: if there are more than three authors you may use the first author's name and et al. EG Brown, H. L. et al.
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