SPE Library

Experiments have been performed to investigate the effectiveness of microwave curing of natural fiber reinforced composites. Industrial hemp, flax, kenaf, henequen and glass (15 weight percent) reinforced epoxy (diglycidyl ether of bisphenol-A (DGEBA) cured with diaminodiphenyl sulfone (DDS)) composites were studied. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and environmental scanning electron microscopy (ESEM) were used to investigate material properties. Samples were processed using both microwave and thermal curing for comparison. Several composites reached a greater final extent of cure with microwave curing. ESEM micrographs indicate a lack of bonding at the interfaces between the fibers and the matrix.

The demands made on elastomeric plastics – particularly those destined for applications where tactile properties are key – are growing ever more rigorous. Many such applications make use of thermoplastic polyurethanes (TPUs), drawing on their excellent properties of abrasion resistance, flexibility, chemical resistance and freedom from plasticizers. To gain the softness desired by the marketplace, TPUs are softened by the addition of plasticizers or compounded with other softer materials. Unfortunately these practices usually come at a cost of reduced mechanical or physical properties or raise potential environmental issues. Bayer MaterialScience has recently developed a new series of softer, processing friendly TPUs that are free of plasticizers and are not compounded with any other materials. The basis of these materials is explained below, illustrated using practical examples.

The environmental regulations, societal concerns, and a growing environmental awareness have triggered the search for new products and processes that are compatible with the environment. Polyhydroxybutyrate (PHB) is a biodegradable polymer that has created significant interest recently because of its renewable resource-based origin. PHB shows susceptibility to fracture when subjected to high rates of deformation. This work investigates toughening mechanisms for PHB via incorporation of functionalizede lastomeric components into the PHB matrix. A compatibilizer was investigated to improve the interfacial adhesion between the incompatible elastomer and plastic phases. The toughened PHB was characterized through their thermo-mechanical, rheological and morphological analysis. The resulting toughened PHB showed more than5 times improvement in impact strength over virgin PHB with around 60 % loss in modulus. The loss of modulus was recovered to permissible extent through incorporation of titanate modified montmorillonite clay. The hydrophilic clay was modified by titanate-based treatment to make it organophilic and compatible with the polymer matrix. Nanocomposites with this modified clay exhibited more than 275% improvement in impact properties with around 40% reduction in modulus in comparison with the virgin PHB bioplastic.

Oxypolypropylenes are high MFR propylene polymers that contain bound peroxide functionalities which can be used as polymerization initiators to produce polypropylene grafted copolymers. Upon heat treatment, the peroxides functionalities in the Oxypolypropylene act as a source of free radicals, reacting with unsaturated double bond of the monomers. The grafting reaction is carried out in the solid state in a reactor. The advantage of grafting via Oxypolypropylene is that it eliminates expensive and environmentally unfriendly organic peroxide. A number of monomers have been grafted on Oxypolypropylene, including vinyl acetate, vinyl pyrrolidinone, methacrylic anhydride, maleic anhydride… Applications of these grafted copolymers in nylon blends or in a glass reinforced formulation are also discussed.

Polylactide polymers have garnered enormous attention as a replacement for conventional synthetic packaging materials since they are biodegradable, compostable, and recyclable. In this study, commercially available PLA films, bottles, and trays were evaluated. PLA films show better ultraviolet light barrier properties than polyethylene, but were slightly worse than polystyrene (PS) and polyethylene terephthalate (PET). PLA films show better mechanical properties than PS, and comparable to those of PET. PLA has lower melting and glass transition temperature than PET and PS. Solubility parameter predictions indicate that PLA will interact with nitrogen compounds, anhydrides, and some alcohols, and it will not interact with aromatic hydrocarbons, ketones, esters, and water. In terms of barrier, PLA showed O2 and CO2 permeability coefficients lower than PS and higher than PET. The amount of lactic acid and its derivatives that migrate to food simulant solutions from PLA was much lower than any of the current average dietary lactic acid intake values reported by governmental organizations.

Composite filtration technology can be implemented less expensively to prevent fossil fuel burning power plants and nonroad and highway heavy-duty engines from releasing green house gases and air pollutants directly into our environments. Carbon-carbon composites (CCCs) were investigated for CO2 filtration from flue gas streams and air pollution filtration such as nitrogen oxide and hydrocarbons from diesel fuel emission. The porous structure of CCC filters was made of chopped carbon fibers and phenolic resin going through curing, pyrolysis and activation. In this study, CCC filters were synthesized under different combinations of pyrolysis and activation times. The structural, physical as well as thermal properties of CCC filters were studied: Scanning Electron Microscopy (SEM) showed the porous structure of CCC filters. Sorption and thermal swing was used for the surface area and adsorption capacity measurements. From the thermal gravimetric analysis (TGA), the thermal properties of CCC filters were investigated. The gravimetric processing has been shown to impact significantly on the filtration performance of CCC filters.

A portable tube-based XRF analyzer provides fast, confident screening and sorting of polymers during manufacture, recycling and disposal. It rapidly sorts PVC, Br- or Sb-based plastics and quantifies Cl, Br and Sb content with excellent detection limits. The analyzer also quantifies As and other toxic metals such as Pb, Cd, Hg, and Cr for compliance with ECD2002/96/EC & RoHS (Restriction of Hazardous Substances) for WEEE (Waste Electrical/Electronic Equipment). X-ray tube-based XRF systems replace the need for multiple isotopes and eliminate their burdensome radioactive source regulatory issues, particularly for interstate and international travel. Integrated PDA & iPAQ Pocket PC affords flexible software, exceptional graphical user interface & conventional MS windows architecture. This also makes available value-added accessories like wireless email and data transfer, global positioning, binary storage, and multiple language display.

The recycling of butyl rubber based tire-curing bladder was carried out by means of a grooved barrel ultrasonic extruder. Die pressure and ultrasonic power consumption were measured as a function of flow rate and ultrasonic amplitude. Gel fraction and crosslink density of the ultrasonically devulcanized rubber were substantially reduced. The latter caused some reduction in gel fraction and crosslink density in the revulcanized rubber. The mechanical properties of the revulcanized rubber, dependent on processing conditions during devulcanization, were compared with that of the virgin vulcanizate. Good mechanical properties of revulcanized rubber was achieved with 86% and 71% reduction of the tensile strength and the elongation at break respectively, and with modulus increased by 44%. The devulcanized rubber was found to contain tiny gel particles of a wide size distribution with a predominant size of less than 4µm.

This paper presents strategies for the manufacture of low-density and fine-celled biodegradable polyester foam sheets blown with CO2 using an annular die. The basic approach is to minimize gas loss by completely dissolving gas, suppressing an initial hump, promoting the number of cell layers across the foam thickness and optimizing the processing temperature. Parametric experiments with various annular dies have been performed to verify the feasibility of the proposed strategies. Low-density biodegradable polyester sheet foams with a volume expansion ratio of over 20 have been successfully achieved even with the gaseous blowing agent CO2.

Core-shell nanospheres have recently emerged as novel drug delivery systems. The performance of the particles depends upon several characteristics including loading capacity, size, composition, etc. The amount of drug that can be loaded into the core is a function of several factors, such as the size and hydrophobicity of the core, the hydrophobicity of the encapsulant, and specific interactions. These parameters are used to optimize the performance of the formulations. In this work, we studied the loading capacity of biodegradable nanospheres as a function of the size of the nanospheres and hydrophobicity of the encapsulant using encapsulants of varying hydrophobicity and different molecular weight linear amphiphilic block copolymers of pullulan and polycaprolactone (PCL). The established relationship is a useful tool in predicting the loading capacity for other substances based on their hydrophobic character and hence in designing an optimum drug delivery system.

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.

This investigation focuses on the inherent recyclablility of a polypropylene homopolymer by characterizing the mechanical and rheological properties of a multiprocessed resin. The investigation studied molded samples both with and without the presence of a weld line. Several blends of virgin and reground polypropylene homopolymer (consisting of 5 recycle histories) were prepared. The tensile properties (including weld strength) and melt flow rate tests were performed on all molded samples from each of the blends.The results of the study showed that regrind did not affect the tensile modulus, tensile strength at yield, or elongation at yield for samples molded without the weld line to any significant degree. The presence of a weld line had a negative effect on the mechanical properties of the molded sample. The weld line strength also decreased significantly as regrind concentration increased. Melt flow rate tests of the various blends showed the melt flow rate increased by a total of 29% over the entire range of regrind percentages studied. Increasing the processing temperature did have a positive effect on the weld line strength. The addition of regrind did not affect the first stage injection pressure or cavity pressure observed during the molding of the test samples.

This paper discusses the thermal and mechanical properties of virgin PET, recycled PET and their blends. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study the thermal properties. The tensile tests at ambient and elevated temperature were used to study the mechanical properties. There were significant differences in the recrystallization behaviour as far as the thermal properties were concerned. In the case of mechanical properties, the tensile test at elevated temperature showed that the strength of the blends of recycled PET/virgin PET were lower than those ones of virgin PET.

Engineering Thermal Plastic (ETP) Suppliers continually look for ways to add value to their products lines enabling them to create more market share. One more recent added value strategy for ETP suppliers has been in aesthetic product portfolios. Colored pigments, dyes, non-dispersing pigments and aluminum flake are added to the supplier’s base resins. Thus creating a portfolio of molded in visual effects for the supplier to offer to their customers.The offering of aesthetic portfolios provides automotive Designers, Marketers, and Engineers with many benefits such as creating Vehicle Brand Differentiation, Cost Out opportunities along with Mass Customization of an application. Other potential benefits can be achieved with molded in effects by eliminating paint and the environmental issues associated with a paint process line. These benefits do not come without some challenges. The addition of these additives can cause property shifts in base resin. Also the use of aluminum flake will create flow line issues.Automotive applications for molded in visual effects typically are styling elements seen on the exterior of a vehicle such as a front grille or in the interior on a console bezel. The interior and exterior application come with their own set of material and performance requirements, which need to met by the supplier’s materials. A careful investigation must be made by the material supplier to matrix the application requirement and the customer chosen molded in visual effect. Part design for molded in effects must also be taken into account for a successful application. Design guidelines differ for aluminum flake additives verse translucent or clear material effects. Finally, consideration of guidelines for processing of the part must be reviewed in order to produce a class “A” surface.A case study of an in production molded in visual effect application will be presented. Nissan Quest Roof rack ends.

This paper offers a glimpse at emerging technology related to the application of composites in automotive structures. In a practical embodiment of this technology composites comprised of thermoplastic polymers and fiberglass are married with a structural core and garnished with a decorative carpet to form an automotive load floor. The exclusive polymer used throughout this particular load floor is polypropylene. Thus the composite structure is comprised entirely of polypropylene and fiberglass. Among the major advantages of this design are the following characteristics: structural integrity low weight excellent thermal stability acoustic abatement incorporation of recycled raw materials and the opportunity for end-of-life component recycling. Regarding processing of this load floor additional key advantages exist such as: low cycle time good formability one-step part consolidation high automation and the low environmental impact associated with thermoplastic polymers. Conceptually products of this type promise to have a lasting impact on the environment through all phases of product life cycle. This is achieved at first by utilizing recycled raw materials going into the product. Next offal from processing is recycled back into the materials stream. In addition the system creates a product of a known common composition of materials which possesses a higher potential for recycling as a whole after the useful life of the vehicle.

Sheet molding compound (SMC) is widely used in automotive parts appliances furniture and construction. These materials heavily depend on the petroleum supply which is depleting fast. The use of plant oils as an alternative source for SMC resins presents economic and environmental advantages over petroleum. Two synthetic methods have been used to develop new resins from triglycerides. The double bonds presented on the fatty acid chains were first converted to epoxy or hydroxyl functionality; the hydroxyl groups were maleinized while the epoxies were acrylated and then further maleinized. When these functionalized oils were combined with 33.3 wt% styrene the polymers showed mechanical properties comparable to those of commercial unsaturated polyesters. In addition these new resins exhibit adequate thermo-reversible thickening behavior with MgO. These triglyceride-based resins have good compatibility with natural fibers such as hemp and flax to form low-cost green composites. New bio-based nanocomposites were also developed using these new resins and organo-treated clays and the nanocomposites showed considerable increase in modulus and toughness. These new green materials show the promise to be used in the automotive industry.

Sustainable nanocomposites have been successfully fabricated from renewable cellulose acetate (CA) environmentally benign triethyl citrate (TEC) plasticizer and organically modified clay. The effects of processing conditions such as mixing methods pre-plasticizing times retention times (RT) and addition of compatibilizer maleic anhydride grafted cellulose acetate butyrate (CAB-g-MA) on the performance of these nanocomposites have been evaluated. The cellulosic plastic with CA/TEC (80/20 or 75/25 wt. %) was used as the polymer matrix for nanocomposite fabrication. The morphologies of these nanocomposites were evaluated through X-ray diffraction (XRD) Atomic force microscope (AFM) and transmission electron microscopy (TEM) studies. From all the sequential mixing methods used powder-powder mixing leads to the most transparent nanocomposites. Cellulosic plastic-based nanocomposites obtained using increased pre-plasticizing times and RT showed better-exfoliated structures. Cellulosic plastic-based nanocomposites with 5 wt.% compatibilizer contents showed better-exfoliated structure than the counterpart having 0 or 7.5 wt.% compatibilizer contents. Polygonal shape of exfoliated clay platelets was observed with 500 nm width and 800 nm length by AFM and TEM imaging. The mechanical properties of the nanocomposites have been correlated with the XRD and TEM observations.

Equal channel angular extrusion creates novel properties in metal and polymer materials. Recently the authors investigated the effects of this process on commercial short fiber composites. Experiments show that ECAE provides a means for controlling fiber length and orientation in the extrudate. The process might transform continuous fiber thermoplastic matrix composite sheets into high volume fraction discontinuous fiber sheet for thermoforming. In addition the process might provide a method of recycling reground components into high-value sheets with a known fiber orientation.

This research work aims to replace glass fibres in sheet molding compounds (SMC) by renewable natural fibres. These eco-efficient and cost effective SMC with natural fibres are gaining much attention in the automotive industry because of their specific properties. The specific objective of the work was to develop a high performance natural fibre hybrid SMC to meet the specifications required for automotive parts such as front fenders body panels etc. Hemp fibres with and without a combination of a small amount of glass fibres were used to reinforce vinyl ester resin for making SMC. Different combinations of layers of hemp and glass fibres were made to prepare SMC. Mechanical properties such as tensile and flexural properties and impact strength of the SMC prepared were found to be highly promising. The current OEM specifications for automotive parts for example rare lift gate and front fenders recommend the composite should have tensile strength of 62 MPa and tensile modulus of 2 GPa (Source of Automotive Engineers Car Technology yearbook 2000” USA 2000 Body panels Properties). SMC prepared by the combination of 45% of hemp fibres and 5% of glass fibres showed tensile strength and modulus were more or less same or better than that of the requirements for car body parts such as rare lift gate and front fenders (Tensile strength greater than 62 MPa and tensile modulus of 2 GPa).Use of this SMC with natural fibre is an economically viable alternative to SMC with glass fibres and at the same time it helps reducing the green house gas emission as there is lesser amount of synthetic resins and plastics.

Most people are aware of what natural fibers are but few know of the diverse capability of this natural resource and unfortunately industry pressures over the past several years to reduce costs focused on trying to refine well established technologies using glass or wood fibers or to a certain extent injected molded polymers. It has only been through recent pressure by some of the larger OEM’s that natural fibers have been gaining broader interest for both their performance and environmental benefits as compared to older more comfortable based technologies. Cost versus performance is a delicate balancing act. Fortunately natural fibers go a long way on striking a balance between both of these most common demands. When considering performance natural fibers offer an unlimited range of lighter weight possibilities for interior and exterior applications. Most common today natural fibers are commingled into a nonwoven mat with fiberized thermo plastic polymers such as polypropylene and polyester for use in common interior applications that include door panels center consoles pillars and inserts. However advancements in the range of available natural fibers and specialty polymers along with a continuous improvement of the nonwoven process are now providing for greater heat stability to meet the elevated requirements for over head systems package trays and topper pads. Increased demands for occupant safety give further reason to consider natural fibers as few other materials provide the same impact characteristics with the base material. For exterior applications natural fiber mats used as the base material in sheet molding compounds will find their way into bumper reinforcements wheel well liners and under hood applications. The industry historically focused on direct material cost. In this simplified approach natural fibers seldom will come out to be the low cost alternative but when considering the benefits derived from one-step processing the end cost of the finis