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 fusion of electronics with glass and plastics to create smart surfaces with a harmonious luxury ambiance is creating a flurry of development activity which is changing the driver/passenger experience in the transportation industry. Merging human machine interface (HMI) displays, controls, and knobs with other decorative plastic components is being driven in part by the desire to reduce/eliminate distractions (safety) in addition to bringing a stylish atmosphere which increases consumer satisfaction. For displays, the desire to move away from the typical two dimensional 7- inch rectangular shape towards larger and different shapes (curved and non-rectangular) becomes a challenge in and of itself because glass has a lower design freedom for forming curvature and tempered glass is considered costly. Plastic covered displays are easier to produce 3 dimensional shapes via either injection molding or vacuum lamination of films, and their light transmitting abilities are similar to glass. As is observed with some glass display surfaces, certain plastics are also prone to birefringence caused by molded in stress which contributes to poor distinctness of image and reading legibility. Choice of polymer and glass surfaces for integrated HMI displays in instrument and door panels, or seat backs is the center of attention given the vast number of requirements of the automotive industry. This paper will focus on the characteristics of bio-based, low birefringent cellulose acetate propionate (CAP) as potential HMI-lens covers in comparison to other clear polymers.
Water-assisted injection molding (WAIM) process has brought a breakthrough development for the traditional injection molding industry. The water cores out a network of hollow channels throughout the mold cavity to reduce the cost of energy and plastic evidently. In the recent years, the improvements both in the numerical methods and computer hardware have promoted the application of CAE in the modeling of the injection molding process. The major drawbacks of the Hele-Shaw approximation, commonly used today as a means of simplifying the simulation of WAIM process, are the inherent loss of the ability to predict the important physical three-dimensional phenomena for water penetration such as blow-out behavior, corner effect and secondary penetration. This study presents an implicit finite volume approach to simulate the three-dimensional mold filling problems encountered during the water-assisted injection molding. Full shot WAIM processes push-back molding process verify mutually with the experimental results on industrial applications. The results show that our novel three-dimensional numerical model is able to predict the complex water penetration behaviors in the real mold and the predictions are also consistent with the experimental results to further verify the accuracy of our approach.
An investigation on the effect of talc content and grain pattern on the scratch and mar behavior of textured thermoplastic olefins (TPO) samples is reported. A set of model TPO samples with different grain pattern and talc content were provided by Nissan Motors (USA) Co., Ltd. Scratch and mar tests were carried out on these TPO samples according to the ASTM D7027-13 standard. The visibilities of the scratch and mar damages were evaluated by a contrast-based methodology, and found to correlate well with human assessment. The grain pattern and talc content are found to have significant effect on mar visibility resistance of TPO. Issues related to mar evaluation methodology and material science on improvement of mar resistance are discussed.
“Worldwide, efforts are underway to save lives and reduce vehicle repair and other economic and social costs that result from motor vehicle crashes. At the same time, also worldwide, automakers are grappling with increasingly stringent fuel economy requirements. The difficulties involved in reconciling these two objectives – designing vehicles that are lighter to improve fuel-efficiency, but also more crashworthy – can seem daunting. This presentation addresses the conundrum head on with a discussion and overview of different multi-material body-in-white (BIW) weight reduction opportunities. The BIW is an obvious choice for vehicle lightweighting as this structure contributes more than 30 to 35 percent of the total weight of a car. Using engineering thermoplastic and hybrid solutions at appropriate locations on a vehicle’s BIW, automakers can achieve significant weight savings without compromising crash performance. To illustrate, this presentation provides a detailed case study on an award-winning floor rocker reinforcement. Also covered are several other lightweight solutions for applications like A/B pillars and bumper rail extensions.”
Pedestrian safety is one of the most important safety criterion that needs to be addressed by automotive OEMs. Additionally, increasingly aggressive styling of the vehicle has posed multiple technical and commercial challenges for OEMs. Having the spoiler positioned at the front end of the vehicle plays a key role in reducing the knee rotation and thus contributes largely to the design of a pedestrian-friendly front bumper system for a vehicle. Design of this spoiler largely depends on the vehicle architecture. This work captures efforts to understand the different vehicle architectures and to develop design strategies needed to meet lower-leg impact performance requirements of pedestrian safety. A hybrid lower member is proposed to meet the pedestrian safety requirements. The proposed solution not only eliminates an additional part in the vehicle front bumper system, but also provides integration possibilities with significant weight reduction potential.
The need for lightweight solutions has increased the use of polymeric materials in many applications, with an aim of replacing multiple components with integrated multi-material and multi-functional polymeric parts. Apart from structural and thermal requirements, acoustic performance is an important functional requirement in many applications such as automotive, transportation, equipment enclosures and consumer electronics. The frequency-dependent acoustic transmission loss (henceforth referred to as TL) is one of the standard measures to understand the acoustic performance and is experimentally measured using an impedance tube setup. The process involves molding and preparing circular samples with two different diameters (for low frequency and high frequency impedance tube testing) and performing repeated tests. The tests are generally repeated for multiple samples of each material and averaged in order to compensate for uncertainties such as sound leakage from boundaries, fitment issues, sample variation, etc. Hence, experimentally determining the TL is expensive due to the labor-intensive and time-intensive sample preparation and testing. TL is a complex function of material composition, morphology, physical and mechanical properties, all of which can be modified for polymers (by using fillers) to achieve the desired TL values in the desired frequency range. As tuning the TL experimentally is a time and cost intensive affair, we have developed a computational model that has been validated with experimental measurements. It is a fully coupled structural-acoustic finite element model simulating the impedance tube. This model can be used to perform virtual design of experiments to arrive at the most likely properties of the polymeric material that will result in the required TL at the frequency range dictated by the application. Only this material configuration can then be prepared and the TL experimentally measured, enabling more quickly identifying a candidate material solution to meet the customer’s needs. In this study, we have experimentally validated the model using test data of TL from five samples of varying composition. This computational tool can be extended to estimate the TL from multi-layered laminates and sandwich panels with various core morphologies.
It is not uncommon for many automotive plastic parts to be painted. Unwanted material, either left from the molding of the part itself, or the picking up of contaminants from the transporting of the part to the paint booth, must be removed prior to painting. Many of these parts are cleaned utilizing aqueous methods requiring that the parts be dried prior to painting. Reclaiming the water, fueling the oven (and dealing with its footprint), and the fact that sometimes the parts don’t get dried, are all problems can be alleviated by utilizing dry ice. Dry ice is a non-abrasive media that does not alter the dimensional characteristics of the part nor damage the surface of the parts to be painted. It is also dry, eliminating the need to have or operate a drying oven. Dry ice also sublimates, leaving nothing to be reclaimed behind and no possible water entrapped in part geometries of complex parts that may not get thoroughly dried. This paper will discuss the distinct advantages of utilizing dry ice as a blast media for the surface preparation of plastic parts prior to painting. The process itself will be explored as well as the common results.
Improving long term corrosion resistance in electronic applications Electronic components have invaded the automotive environment with increasingly complex designs and functionality. In addition, the location and environment of these components continues to drive the requirements to higher performance materials. The combination of exposure to electrical potential, moisture, elevated temperature and environmental salt can affect the performance of electronic components. DuPont has developed a line of “EF” Electrically Friendly resins which will help reduce the risk of long term corrosion or performance degradation in aggressive environments.
Advances in Hydrolysis resistance PBT resins for electronic applications including connectors and HEV components DuPont has developed a new PBT hydrolysis resistance technology to offer outstanding melt stability during molding. The process flexibility of this family of resins allows for more stable manufacturing processes and improvements in quality versus existing PBT HR grades on the market. This unique combination allows a wider processing window, including the use of hot-runners and regrind, without sacrificing the hydrolysis resistance as well as additional benefits for high voltage connectors and electronic applications
During the regeneration of tissues and organs, growth factors (GFs) play a vital role by affecting cell behavior. However, because of low half-life time and quick degradation of GFs, their stimulations on cells are relatively short and discontinuous. In our study, a releasing scaffold platform, consisting of polycaprolactone (PCL) nanofibers and vascular endothelial growth factor (VEGF)-encapsulated gelatin particles, has been developed to extend the influence of GFs on mesenchymal stem cells (MSCs) and endothelial cells (ECs). The results showed that this kind of scaffold could direct the differentiation of MSCs to ECs and maintain the stability of its tubular structure for an extended period of time, thus suggesting its potential application in vascular tissue engineering.
Biodegradation was measured for biodegradable, compostable, and oxodegradable plastics while exposed to aerobic composting, marine, and anaerobic digestion environments. Biodegradable plastics included, corn-starch based biobag, PHA bag, Ecoflex bag, and PLA lids. Positive and negative controls included, Kraft paper and polyethylene. Other plastics included, and oxodegradable plastic bags. For industrial composting environment, compostable plastic products, along with oxodegradable, cellulose paper, Kraft paper, and polyethylene plastic wrap, were placed in an environment consistent with ASTM 5338 conditions. For marine environment, the plastic samples were placed in a test environment consistent with ASTM 6691. For anaerobic digestion, plastic samples were placed in an environment consistent with ASTM 5511. The degradation was evaluated by measuring CO2 gas, which evolves from the degrading plastic samples. For industrial compost conditions, the compostable plastics, namely, PLA, sugar cane, PHA, Ecoflex, and starched-based biobag, degraded at least 90% and met the degradation time requirement in the ASTM D-6400 standard. The oxodegradable, UV-degradable plastics, and LDPE plastic bag had negligible degradation. After 180 days placed in a commercial food-waste composting operation, PLA, PHA, Ecoflex, and corn starch plastics completely degraded. Small fragments of sugar cane lids and Kraft paper were visible. The oxo-biodegradable plastic bags, LDPE plastic bags and UV-degradable plastic bag did not fragment nor degrade. The samples were also exposed to a simulated marine environment. Under marine conditions, PHA experienced significant biodegradation. Alternatively, corn-starch based trash bag, PLA cup, Ecoflex bag, sugar cane lids, UV-degradable plastic ring, and Kraft paper did not exhibit biodegradation under marine conditions. Under anaerobic conditions PHA experienced biodegradation, but PLA, paper, and polyethylene did not.
In this study, trypsin hydrolyzed gliadin (THGd) from wheat was used as a curative and reinforcing filler in synthetic isoprene rubber (IR). Curing kinetics of the THGd compounds demonstrated that THGd was most effective when utilized as an activator in place of zinc oxide and stearic acid (ZnO/STE). The THGd vulcanizates exhibited comparable or higher moduli to the control, but lower crosslink densities and slower curing kinetics. THGd was able to facilitate crosslinking, as shown by swelling experiments, but further study is needed to match/exceed the kinetic properties of the control. Interestingly, THGd was very effective as a reinforcing filler and reinforcement increased as a function of molding time. Thus, rubber processing was favorable to the self-assembly of hydrolyzed protein into a reinforcing phase.
The lack of commercially relevant compatibilizers from renewable sources is limiting the usage of biopolymer blends and composites in today’s market. This work studies potential new compatibilizers that can be used in applications involving blends of sustainable polycarbonates and polyesters. Poly(propylene carbonate) (PPC) and poly(butylene succinate) (PBS) were functionalized separately using maleic anhydride (MAH) and an initiator to trigger free radical grafting. Different amounts of MAH were used during the melt compounding to study the effect of the MAH amount on the extent of the reaction. The resulting compounds were examined by means of titration, proton NMR and parallel plate rheometry. Formulations using both PPC and PBS successfully reacted with MAH, as evidenced by the appearance of new chemical shifts in their proton NMR spectra associated with midchain grafting and end groups reactions. The PPC compounds showed an increase of the grafting efficiency with addition of more MAH. The PBS formulations had maximum grafting efficiency value at 2% MAH. Rheometry showed that incorporation of 2% of MAH and DCP produced an increase in the viscosity of both PPC and PBS in comparison to their neat counterparts. Evaluating all these results together, it can be concluded that the PPC with 2% MAH and DCP is the most reactive compound and the one that could perform more efficiently as a compatibilizer. In addition, melt compounding presents an economic method to produce biocompatibilizers of high reactivity and high molecular weight.
The valorization of side-steam products from bio-refinery is of crucial interest to develop further the viability of a bioeconomical system. The corn oil is one of the important co-products from the bioethanol industry with a production of more than 2.7 billion pounds in 2015 in USA.  In this investigation we propose to create new materials with higher added value by developing new monomers and polymers through transamidation and successive polyesterification. The resulted sustainable materials can be used as toughening agent for both thermoplastic and thermoset polymers.
With increasing interest towards biobased and/or biodegradable polymers that generate high performance composites, instead of petroleum based products, creates new opportunities and research challenges. Poly (butylene succinate) (PBS) is supposed to be one of the most promising biodegradable polyesters because of its good mechanical strength and high heat deflection temperature. However, the low impact strength of poly (butylene succinate) (PBS) has limited its application in some fields. Therefore, poly (butylene adipate-co-terephthalate) (PBAT) and poly (butylene succinate) (PBS) were melt-compounded to fabricate a novel PBS/PBAT blend to improve the impact strength of PBS. The effect of PBAT on the properties of the final binary blends, including mechanical properties, thermal properties and rheology properties, is studied in this research. Rheological properties revealed a strong shear-thinning tendency of the blend resulting from the high compatibility between PBAT and PBS. The partially compatibilized PBS/PBAT blends show high tensile strength (~50 MPa), high impact strength (~200 J/m) and a moderate tensile modulus (~500 MPa). A PBS/PBAT system can be a good candidate to fabricate high impact biodegradable products.
In recent decades, poly(butylene succinate) (PBS) has been attracting attention as a promising and important polymer in the bio-based and biodegradable polymer family due to high thermal resistance and good mechanical properties. However, compared with other biodegradable polyesters (e.g., poly (lactic acid)), the high cost of PBS limits the widespread applications, especially for the packaging industry. In this paper, PBS-based copolyesters were prepared successfully by a two-stage melt synthesis, and degradability of the polyesters was investigated. It was found that the degradability of PBS could be tuned over a wide range by adjusting the degradation catalyst and lowering crystallinity by forming random copolymers. Based on our previous work on the tunable properties of PBS-based polyesters, the degradation results indicated that the enzymatic degradation mainly depends on the morphology and thermal properties, while the ratio of ester groups in polymer is the crucial factor for base-catalyzed hydrolysis.
Natural insecticide, pyrethrum, and insect repellent DEET were added to poly(lactic acid) (PLA) fibers via extrusion and spraying. GPC analysis showed that the addition of DEET caused an increase in depolymerization with the increase of DEET concentration. Contact Irritancy Assay (CIA) showed that DEET-treated PLA fabrics caused the lowest percentage escape response with an escape frequency of 33.3 ± 3.3%. This was followed by the extruded natural pyrethrum-treated PLA fabrics with an escape frequency of 80 ± 6.3%. PLA fabric spray-treated with natural pyrethrum caused an escape frequency of 98.3 ± 1.7%. All treated fabrics caused repellency.
The shish-kebab structure has been investigated for many years and it has been widely applied in many field, while the formation of the structure has still been found in limited materials. In this study, different electrospun poly(ε-caprolactone) (PCL) blended nanofibers with poly (ε-caprolactone-co-lactide) (PLCL), polylactic acid (PLA) and graphene (GO) were applied as shish materials in the self-induced crystallization and different crystalline structure were obtained. The PCL blended fibers with different internal crystalline structure led to different induced crystal lamellae morphology. By comparing with the surface crystalline structure, it seems that the formation of self-induced nanohybrid shish-kebab (SINSK) structure is regulated simultaneously by a lattice matching mechanism and a soft epitaxy effect in the crystallization process. This study might help people to explore the materials for creation of SINSK structure.
Polylactic acid (PLA), derived from bio-resources, is an environmentally friendly plastic which has attracted tremendous interests in both academia and industry. This paper investigates the feasibility of direct injection molding of PLA/wood fiber composites and their mechanical behavior. Response surface methodology was adopted to study the effects of molding parameters, as well as their interacting effects, on the tensile strength of the composites. Melt temperature, hold pressure, injection speed were chosen as the molding parameters studied. Additionally, the analysis of variance was applied to identify the most significant factors. The statistical model would improve our understanding of the tensile strength behavior of PLA/wood fiber composite, and provide the guidance for selecting proper molding parameters to maximize the tensile strength.
This study describes the preparation and characterization of electrospun films made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) produced by mixed bacterial cultures derived from a cheese whey (CW) industrial by-product. A mild thermal post-processing step carried out on the electrospun fibers mat, at a temperature below the biopolymer’s melting point, yielded a film with high transparency, enhanced crystallinity, and potentially sufficient mechanical and water barrier properties for sustainable packaging applications.
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