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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Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
Gas-Assisted Low Temperature Bonding of Polymeric Micro/Nanostructures
Polymer-based biomedical micro/nanodevices containing environmentally sensitive biomolecules are attracting increased interest. A critical requirement is the ability to assemble these devices at low temperatures in order to minimize denaturization. Studies of polymer thin films revealed that the properties at the polymer surface differed from those in the bulk. It was found that glass transition temperatures (Tg) at the polymer-air surface was substantially lower than the bulk Tg and increased toward the bulk value with depth from the surface. Subcritical CO2 could enhance the chain mobility and greatly depress Tg near the surface. Benefiting from this, we successfully demonstrated low temperature bonding of polymeric micro/nanostructures. The original micro/nanostructures are perfectly preserved after bonding.
Human Osteoblast Development on Polycaprolactone and Polycaprolactone/Hydroxyapatite Composite Scaffolds for Tissue Engineering
The study investigated the growth and adhesion of normal human osteoblasts (NHOst) to two different biodegradable systems. These materials included polycaprolactone (PCL) and polycaprolactone/ hydroxyapatite (PCL/HA) composite.We studied the attachment of osteoblasts to two-dimensional films of these materials. We specifically looked at the potential of these two biodegradable systems to promote bone tissue growth. The materials were cast into two-dimensional films. They were evaluated for functionality, growth and adhesion at designated intervals using microscopy and bone-specific alkaline phosphatase (BAP) and osteocalcin (OC) immunoassays.The cells on the composite scaffold produced more BAP than the cells alone or on the PCL scaffold. However, the cells on both types of scaffolds showed lower levels of OC than the cells alone.
Hygrothermal Aging of Recycled-PET Sandwich Injection Moldings
Thermal instability and hydrolysis have been the major factors and driving force behind the continued efforts by researchers to improve the properties of recycled poly(ethylene terephthalate) (RPET) in order for them to be considered useful. This study aims at enhancing the resistance of RPET moldings to hygrothermal aging without making any chemical modifications to the resin. The only means of modification that is done here is through alterations in terms of processing conditions and techniques. The sandwich injection molding technique is capable of producing specimens with a distinctive skin and core structure. Water absorption rate of the sandwich moldings was found to be much lower compared to conventionally molded specimens. Tensile and bending properties have also shown significant improvement favoring the sandwich specimens. The change in morphology due to ‘double-resin-flow’ in sandwich injection moldings could have created a layer between the skin and core that has excellent barrier properties that prevents water absorption into the inner parts of the specimens.
Injection Molded Novel Green Materials from the Byproduct of Corn Based Ethanol Industry
The corn gluten meal (CGM) is one of the major byproducts of ethanol industries. The current use of CGM is more towards livestock feed. This research looks forward in using CGM in making novel biodegradable plastics by blending with one petroleum-derived biodegradable polymer like poly (?-caprolactone), PCL. The CGM was plasticized with glycerol and destructurized with guanidine hydrochloride (GHCl) followed by blending with PCL. Extrusion followed by injection molding processing was adopted in fabricating the new blended green materials. The processing conditions affected the performance of the blends. The resulting green materials were studied for their mechanical properties using dynamic mechanical analyzer (DMA), united testing system (UTS) and izod impact tester.
Investigating Flow Behavior of Wood-Plastic Composites
The trend toward increased usage of renewable resources has led to the growing popularity of wood-filled materials. These emerging materials require extensive testing – beginning with formulation and ending with the final manufactured product. In the early stages of development, it is possible to acquire data comparing differences between recipes utilizing a Mixer/Measuring Head. The given blend can be compounded with a customized twin screw extruder and torque rheometer. Finally, a single screw extruder can quantify the rheology of the compound using a capillary die. The objective of this work is to investigate the behavior of a polyolefin based wood-filled compound using a torque rheometer.
Microwave Processing of Chopped Natural Fiber Composites and Their Thermal and Morphological Characterizations
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.
Next Generation of Soft TPUs
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.
Novel Green Nanocomposites from Toughened Polyhydroxyalkanoate and Titanate Modified Montmorillonite Clay
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.
Oxypolypropylene as a Radical Initiator for the Production of Polypropylene Grafted Copolymer
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.
Polylactides. A New Era of Biodegradable Polymers for Packaging Application
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.
Polynanomeric Composite Technology Applied to Environmental Filtration Processes
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.
Portable, Tube-Based XRF Analyzer for Quick PPM-Level Metals Analysis in Polymers
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.
Recycling of Butyl Rubber by Ultrasonic Devulcanization
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.
Strategies for the Manufacture of Low-Density, Fine Celled PBS Sheet Foams Blown with CO2 Using an Annular Die
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.
Study of the Loading Capacity of Biodegradable Core-Shell Nanospheres
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.
Surface Modification Techniques for Optimizing Adhesion to Automotive Plastics
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.
The Effect of Recycle History and Processing Temperature on the Weld Line Strength of a Polypropylene Homopolymer
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.
Thermal and Mechanical Properties of Recycled PET and its Blends
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.
Using Aesthetic Additives in Engineering Thermal Plastics for in Mold Automotive Applications
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.
Biobased Nanocomposites from Toughened Bacterial Bioplastic and Titanate Modified Layer Silicate: A Potential Replacement for Reinforced TPO
Biobased ‘green’ nanocomposites are the materials for the 21st century. Polyhydroxybutyrate (PHB) a bacterial bioplastic is recently highlighted because of its renewable resource based origin and its potential to replace/substitute petroleum derived non-biodegradable plastic like polypropylene (PP). The major drawback of PHB is its brittleness. This work investigates toughening mechanisms for PHB via incorporation of elastomeric components. Maleated polybutadiene with high grafting and low molecular weight was identified as the compatibilizer. The toughened PHB was characterized through their thermo-mechanical rheological and morphological analysis. The resulting toughened PHB showed ~440% improvement in impact strength over pure PHB with only 50% 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. The toughened PHB on reinforcement with 5 wt.% titanate based modified clay gave ~400% improvement in impact properties and 40% reduction in modulus over virgin PHB. The novel toughened bioplastic nanocomposites show potential as a green replacement/substitute of specific TPO for use in structural applications.
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