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.
United States Army warfighters in theater are often faced with the challenge of broken, damaged, or missing parts necessary to maintain the safety and productivity required. Waste plastics can be utilized to improve the self-reliance of warfighters on forward operating bases by cutting costs and decreasing the demand for the frequent resupplying of parts by the supply chain. In addition, the use of waste materials in additive manufacturing in the private sector would reduce cost and increase sustainability, providing a high-value output for used plastics. Experimentation is conducted to turn waste plastics into filament that can be used in fused deposition modeling. The effect of extrusion temperature and number of extrusion cycles on polymer viscosity and crystallinity are explored. The effect of blends and fillers to impart additional functionality are also examined. Tensile specimens were tested and compared to die-cut and injection molded parts. Parts printed from recycled polyethylene terephthalate had the highest tensile strength of all recycled plastics evaluated (35.1 ± 8 MPa), and were comparable to parts printed from commercial polycarbonate-ABS filament. Elongation to failure of all recycled plastics was similar to their injection molded counterpart. In addition, select military parts were printed with recycled filament and compared to original parts. This research demonstrates some of the first work on the feasibility of using recycled plastic in additive manufacturing.
Four different soy additives were compounded into Linear Low Density Polyethylene (LLDPE). The four different additives were compounded and pelletized by FKuR. After a film was produced for each of the four batches, the mechanical, barrier, and thermal properties of each batch was characterized and compared to a control sample. The use of soy in polymeric films improved mechanical properties in LLDPE, reduced the cost and amount of plastic used, and improved water vapor barrier of the polymer. The modulus of each film increased with the use of filler. However, the ultimate extension and ultimate tensile strength decreased in the samples containing soy fillers. The films showed increased crystallinity in samples containing soy fillers. Additionally, thermal analysis indicated large amounts of weight loss in the soy loaded films when heated.
Accelerated aging is used throughout the Medical Device sector and other sectors to evaluate materials and devices in an accelerated fashion. If used properly, it can shave years off of validation efforts. If used improperly, it can generate misleading or completely incorrect data about the resins and products in question. This paper explores the fundamental principles and provides supporting data. It is critical to understand the four primary modes of aging for polymers: (1) physical aging (embrittlement and loss of free volume); (2) chemical aging, which includes oxidation, chemical damage, sterilization, etc.; (3) sustained strain cracking, creep rupture, and environmental stress cracking; and (4) fatigue. For sustained strain or sustained load environments, stress relaxation and creep are also key factors. A case study is presented for polycarbonate and copolyester resins that are undergoing physical aging, sustained strain cracking, and environmental stress cracking (ESC), and a model presented to account for the various factors.
In this work, we propose an environmentally friendly innovative ultrasonic process to impregnate solventless epoxy into carbon nanotube (CNT) nanopaper (NP) (approximately 50 um thick) for fabricating prepreg nanocomposites. Both multi-wall carbon nanotube (MWNT) NP and single-wall carbon nanotube (SWNT) NP are used for prepreg fabrication. The prepregs show multi-functional performance in EMI shielding and sand erosion resistance. Process parameters including ultrasound time, amplitude level and pressure are studied for the fabrication process.
Schulamid RD “reduced density” nylon is obtained through an immiscible polymer blend which requires the optimization of the compatabilization system, component viscosities, and, most of all, design of the compounding process. In addition to low density, low moisture absorption is achieved which provides part designers with more predictable physical properties and part dimensions when their application is exposed to real environmental conditions. For processors, lower moisture absorption means less moisture to remove. Cost savings can be realized by the reduced melt temperatures that can be used due to the improved flow characteristics of Schulamid RD. Less heat added means less heat to remove which reduces energy consumption for the entire process. A tailored heat stabilization technology has allowed use in under the hood applications like active grille shutters, fan shrouds, and other components requiring temperatures up to 150C.
Mango Materials has developed an innovative platform technology to turn waste gas streams into ecofriendly, biodegradable materials at competitive economics. Utilizing a biological process, microorganisms convert the carbon from methane into polyhydroxyalkanoate (PHA), which can be formulated to produce various products. The recent application development of biodegradable bio-polyester production will be highlighted. By substituting persistent polyester with this biodegradable bio-polyester made of PHA, brands can finally produce truly sustainable garments. Until now PHA has never been developed into commercial textile fibers, making this discovery an opportunity to accelerate the market growth of PHA.
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.
Discontinuously produced polyurethane (PU) foams can be found in various applications and branches. Typically used blowing agents show significant economic or ecologic disadvantages. Using CO2 as a sustainable blowing agent displays different processing challenges. In this context the influence of gas-counter pressure, which is introduced in the cavity of the mold before injection, and of the CO2-amount on the foaming characteristics and the foam-morphology have been analyzed.
Accurate understanding of changeover time (i.e., the time it takes to change formulations) in a blown film line can minimize waste and maximize production. Previous work examined changeover time in extruders, and residence time distribution for blown film [Wang et. al., ANTEC Tech. Papers, 2015, Wang et. al., ANTEC Tech. Papers, 2017]. This work uses transmission UV-Vis spectroscopy with a copper phthalocyanine tracer to examine the factors affecting changeover time for a blown film line. Our results show that throughput is the strongest factor influencing changeover time, and material rheology is a weaker but potentially important factor.
A novel depolymerization method using low-temperature, low-pressure alcoholysis of PLA in a ternary solution is outlined in this work. Depolymerization kinetics are studied for the PLA/methanol/chloroform system at 57°C. Large changes in molecular weight can be achieved at relatively mild conditions. A tin catalyst is found to increase the reaction rate significantly. The method is well-suited to industrial recycling processes and is consistent with the concept of a circular economy.
The mechanical properties of sisal-PLA composites were measured with a parameter of length of sisal fiber, degree of microfibrillation, and mixing method of sisal fiber. The mechanical properties of sisal-PLA composites were also compared with those of wood flour, cellulose based on hardwood, and cellulose nanofiber composites. As a result, the higher tensile strength of the sisal-PLA composite was obtained by kneading PLA and microfibrillated sisal fiber wetted with organic solvent.
Glass fiber/nanocellulose/epoxy interfacial adhesion was explored to determine the optimum coating process and nanocellulose surface chemistry for glass fiber reinforced epoxy composites. The interfacial adhesion was assessed by photoelastic scattering under a microscope and interfacial shear stress (IFSS) determination by single fiber fragmentation test (SFFT). The effect of nanocellulose as glass fiber coating on the interphase was determined and prospects of nanocellulose sizing of glass fibers (GF) were discussed.
Wood-plastic composites (WPC) are composite materials made of wood fiber/wood flour and thermoplastics. Since a polyolefin-based resin, generally used in WPC, exhibits hydrophobicity, it shows low interfacial adhesion when mixed with hydrophilic wood flour, which causes a problem in that flexural strength of WPC is lowered. In case of a polyvinyl chloride (PVC) resin, a phthalate-based plasticizer and stabilizers containing heavy metals can be used in order to enhance processability during the process to make WPC, which are easily extracted out from WPC, causing an environmental pollution problem. Both PP and PVC based WPC are vulnerable to climate changes due to its low dimensional stability according to temperatures, causing many defects and problems. In case of polyester (PET) resin, polyester base resins compatibilizes well with wood, but due to high processing temperature, the wood flour are burned during the process, which makes it impossible to use PET for WPC. Accordingly, in order to solve the above-described problems, ECOZEN® based WPC has been developed. ECOZEN® based WPC has improved physical properties which show superior flexural property (higher than 2 times compared to PP based WPC), impact strength, and lower thermal expansion (or shrinkage). Also it can be easily processed even without help of additional coupling agents, since ECOZEN® shows excellent interfacial adhesion with wood flour. This allows of WPC with higher content of wood flour, which benefits in terms of cost competitiveness and environmental friendliness.
Poly(Lactic acid) (PLA) is a typical biodegradable and bioabsorbablesemicrystalline material and has drawn extensive attention due to its excellent biodegradability, biocompatibility and mechanical properties. The semicrystalline PLA has a low crystallinity and the crystallite is imperfect which affects the properties of PLA parts. In this study, the effect of annealing on the composite nanofiber of PLA and graphene oxide(GO) and carbon nanotubes(CNT) is investigated. Nanofibers of PLA, PLA/GO and PLA/CNT are successfully prepared. A serials of characterization on crystalline morphology on the nanofibers suggest that the addition of GO and CNT enhance the crystallization of PLA and the enhancement effect of GO is better than that of CNT. Annealing improves the degree of perfection and crystallinity of PLA nanofibers. With the increased annealing temperature, the improvement becomes more significant. The results reveal that annealing is a favorable method to tuning the crystalline of PLA and its composite nanofibers, which allows to optimize other properties for the nanofibers.
This research focuses on the characterization of bioplastics joined using ultrasonic welding and modeling of temperature distributions and interfacial healing. Polylactic acid (PLA), which is typically derived from starch-rich crops such as corn, was studied. While the measurement of activation energy for interfacial healing at weld interfaces of PLA films has been reported, here, this information is used to predict the weld strength of rigid PLA samples welded by ultrasonics. A characterization of the mechanical properties was completed with a tensile test to determine the effects of amplitude, weld velocity and collapse distance on weld strength. From previous interfacial healing activation energy measurements based on an impulse welding method, it was also possible to predict weld strength. It was found that the most influential parameters were weld time, collapse distance and weld velocity. In general, the model predicted weld strength reasonably well with r2 values between 0.77 and 0.78.
Friction Riveting is an innovative and promising joining technology, which can potentially fulfill the industry requirements for sustainable and efficient systems. The objective of this work is to prove the feasibility of Direct-FricRiveting by inserting a metallic rivet through metal-composite overlapped plates and subsequent anchoring in the composite part, which is a challenging configuration with limited knowledge available. The case-study joint configuration used in this work comprised a Ti6Al4V rivet, which joined an overlapped AA2024-T3 upper plate with a 30% short-carbon-fiber-reinforced poly-ether-ether-ketone lower plate, material combination of high interest for the aircraft industry. Evaluation of joint formation, temperature development, microstructural and physicochemical changes in the composite, and mechanical properties were carried out for joints produced under low and high energy input. The feasibility was proved, showing satisfactory mechanical performance under lap shear testing (up to 7 ± 1 kN). Changes of polymer crystallinity and thermo-mechanical decomposition in the composite were shown not to affect the joint mechanical performance and failure behavior, while the plastic deformation at the rivet tip played the major hole. The knowledge gathered in this preliminary work will be further applied to optimize the process, contributing to the development of the Friction Riveting technology and improvement of its industrial applicability.
Since powder coatings do not use VOCs, much research has been studied as eco-friendly paints. Among these powder coatings, hybrid type is widely used in home appliances and furniture. Therefore, it is very important to meet both aesthetic characteristics and mechanical properties such as gloss and hardness. However, it is difficult to maintain high gloss with high hardness because of the inorganic filler of powder coatings.
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.
The effect of biodegradable additive (Biosphere) on the spherulite growth rates of isotactic polypropylene was studied by means of polarized light microscopy. It has been found that the addition of biodegradable additive to isotactic polypropylene matrix increases the intensity of the spherulites at all covered isothermal crystallization temperature in the range from 125 to 145 oC. In comparison with the neat isotactic polypropylene spherulites, much smaller spherulites were obtained at all crystallization temperatures for the isotactic polypropylene/biodegradable composite. The obtained results show that the presence of the biodegradable additives enhances spherulite growth rate at low crystallization temperatures (below 135 oC) while the effect of these additives is almost negligible at high crystallization temperature (above 135 oC).
We study and report on the effect of different fillers on the coefficient of linear thermal expansion (CLTE) of polypropylene (PP) by melt extrusion technique. We examine and review the effect of some fibers such as glass fiber and carbon fibers as well as traditional mineral filler like talc. Moreover, we study the effect of new biocarbon as an environmentally friendly filler on the CLTE of neat PP and compare with the previous samples. On the basis of these results, properties and potential applications of PP composites are discussed.
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