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.
Porous materials and foams are widely used for sound absorption purposes in different sectors. To answer the needs for light weight compact noise insulation material with high sound absorption capability, the microstructure of porous membranes can be designed for optimum performance while occupying the same volume with the same weight. Such engineered structures are known as Functionally Graded Material (FGM). In the present study, novel functionally graded foam with superior sound absorption is introduced and compared to uniform foams of the same porosity. The designed graded membrane demonstrates 20% improved performance. Foams are fabricated from bio-based polymer (Polylactide (PLA)) and are environmentally friendly.
Nucleation is one important tool for tailoring mechanical and optical properties of polypropylene (PP) as well its processability in various conversion technologies. Especially the latter aspect is gaining more and more importance in the light of sustainability and energy efficiency discussions, as shorter cycle times and high line speeds are aspired. The efficiency of a nucleating system is commonly determined by the crystallization temperature (Tc) of the resin as measured by differential scanning calorimetry (DSC), typically at 10 K/min. However, Tc is strongly dependent on the cooling rate. Thus, at processing relevant conditions (cooling rate 100-6000 øC/min resp. up to 100 K/s) a suppression of the nucleation effect is frequently observed, and in certain cases the nucleating agent can become completely ineffective. In this study, the crystallization behavior of polypropylene heterophasic copolymers, containing state-of-the-art nucleating systems has been compared. Non-isothermal and isothermal crystallization experiments were performed by DSC and by fast scanning chip calorimetry (FSC) at cooling rates between 0.02 and 3.000 K/s. The data obtained suggest significant differences regarding the crystallization rate. The results are discussed in light of the molecular architecture of the polymer and the type of nucleating system.
Due to the high demand of smart green, the lightweight technologies become the driving force for people in automotives and others development in recent years. Among those technologies, using short and long fiber-reinforced thermoplastics (FRT) to replace some metal components can reduce the weight of an automotive significantly. However, the microstructures of fiber inside plastic matrix are too complicated to manage and control during the injection molding from screw, to runner, to gate, and to cavity. In this study, we have integrated the screw plastification, to injection molding for fiber microstructures investigation. More specifically, paid most of our attention on fiber breakage prediction during screw plastification. Results show that fiber breakage is strongly dependent on screw design and operation. When the screw geometry changed, even the compression ratio is lower, the fiber breakage could be higher.
Our industry leading separation technology enables us to recover polyolefin and styrenic plastics from complex mixed streams such as shredded end-of-life vehicles. Plastic flakes recovered using our process are compounded and sold as pellets suitable for use in injection molding and extrusion applications. This paper looks at the challenges and benefits of recovering plastics and modifying their properties for use in various injection molding and extrusion applications in the horticultural, construction, packaging and automotive industries.
Biodegradable nanocomposites were prepared from poly(butylene succinate) (PBS) and isora nanofiber (INF), a cellulosic nanofiber extracted from Helicteres isora. The nanocomposites were processed using a brabender twin-screw compounder and an injection-molding machine. The effects of INF on the mechanical (tensile and flexural), viscoelastic and thermal properties of the nanocomposites were investigated. The tensile and flexural moduli of PBS-INF nanocomposites increased with INF content, whereas the toughness and strain-at-break decreased. The tensile and flexural strengths increased up to 1.5phr INF loading beyond which they declined owing to agglomeration of INF. The storage modulus of the nanocomposites increased with the INF content. The addition of INF did not affect the Tg significantly. The area integration under tan ë curve decreased with INF loading indicating that PBS-INF nanocomposites exhibited more elastic behaviour with increasing INF. The addition of INF did not alter the thermal stability of PBS, significantly.
Talc, glass bead and poly(ethylene glycol) (PEG) were used for developing moisture absorption and improving crystallization of recycled poly(ethylene terephthalate) (RPET). RPET and fillers were compounded in twin screw extruder with using air drying along the conveyer to yielding high crystallinity of the compounds. The effect of additional fillers and PEG on intrinsic viscosity, moisture absorption, crystallization and rheological behavior was investigated. The incorporation of fillers and PEG slightly decreased intrinsic viscosity and yielded lower moisture absorption rate than neat RPET. Crystallization kinetic parameters indicated that RPET compounds were faster crystallization, which resulting in higher crystallinity than RPET. Rheological properties of RPET compounds decreased at higher talc contents and the addition of PEG. It can be noted that RPET compounds were lower moisture contents, higher crystallinity and better rheological properties at lower shear rate, which would improve mechanical properties of talc and glass bead filled RPET compounds.
Elastomers are wide-meshed cross-linked (vulcanized) polymers and recycling is difficult. Thermoplastic materials can be molten by exposing them to thermal energy and put into different shapes or mixed with other ingredients to form new compounds. Elastomers do not have a melting point, in order to put them into different shapes or mix them with other materials, first the cross-linking has to be broken and the elastomer plasticized again, in other words ?de-vulcanized?. Since this is much more difficult than just melting, in comparison to thermoplastics, elastomers, due to this difficulty, were mainly reduced in size and added as filler in other materials or burned for energy and not recycled into the original raw materials. However, until today there existed no continuous economical process that has been established in the industry.
Compounds of soy flour, biochar and a polymer matrix, such as PLA, have proven to be effective fertilizers comparable to commercial products. Prototype composites achieved NPK values of 2.85, 0.20, 0.49 and 3.08, 0.21, 0.48 %, respectively for PLA- and PHA-based composites. These composites only leached a fraction of nitrogen compared to a commercially available synthetic fertilizer. Low leachate values, as compared to commercial fertilizers, may be associated to the absorption and releasing of nutrients by biochar. The nitrogen within the soy is also not readily water soluble and is released over time by microbial action.
Studies on the development of high performing ABS/PLA polymer blends have been done. The mechanisms of individual polymers have been investigated, showing the crystallization of PLA can highly influence its toughness. This can be controlled through process engineering during the molding of the polymer. In addition, ABS has been shown to undergo a crosslinking reaction during the timeframe of melt processing. Understanding these mechanisms has been crucial in the development of high performing ABS/PLA blends that have similar properties to the original ABS. These blends and their properties are discussed.
Investigation of curing kinetics of a biobased thermoset resin was the aim of this study. The curing reaction involved a combination of a petroleum based epoxy resin (diglycidyl ether of bisphenol A) and a biobased epoxy resin (epoxidized soybean oil) with a biobased curing agent (sebacic acid) and was evaluated using a differential scanning calorimeter. It was found that the addition of ESO increased the enthalpy of reaction as well as activation energy. Kissinger-Akahira-Sunose (KAS) and Starink methods have been used to analyze the results.
As electronic devices become smaller and more powerful, heat concentration and as a result heat dissipation would highly affect their efficiency. Also with rising awareness about environmental protection, using bio-based (green) materials as electronic packaging is more important than before. In this context in this research liquid crystal polymer (LCP), hexagonal boron nitride (hBN) high thermally conductive composite fibers were produced and effects of LCP-hBN fiber content and aspect ratio in composite with Poly-lactic acid (PLA) on effective thermal conductivity of the composite were studied. Based on previous studies the largest thermal barrier effect against increasing thermal conductivity of composite is filler particles percolation and phonon scattering at filler particles boundaries. In this study it is observed that the same thermal conductivity as pure fiber can be achieved in composite with lower fiber loading, as long as suitable fibers interaction exist at optimized fibers aspect ratio. This suggest that at right filler content and aspect ratio it is possible to eliminate filler percolation thermal barrier effect and transfer all of the received phonons through the composite thermal pathways rather than scattering them.
Surface quality remains one of the biggest problems when manufacturing products using selective laser sintering (SLS). Several experiments were performed using different SLS input variables in order to manufacture samples with different surface characteristics. The effect of virgin or recycled powder, the laser power utilized, and the roller speed were studied and related to surface defects. An Alicona metrology system, with a 4th axis for rotating and imaging tools system was utilized to analyze samples. The three main quantities investigated were average surface roughness, root mean square roughness and ratio of areas. Bearing area curves were also examined.
The synthesis of biopolyesters based on refined crude glycerol and succinic acid was studied aiming to determine the influence of the molar ratio of reactants (glycerol to succinic acid) in the extent of reaction and main physic chemical properties of the products. Industrial crude glycerol refined up to 96 wt% glycerol content was employed as monomer for the synthesis along with succinic acid and the reaction was stopped before reaching the gel point in order to obtain non cross-linked products. These polyesters were characterized by gas chromatography, FTIR and thermal gravimetric analysis. It was shown that the molar ratio of reactants employed determines the amount of unreacted monomers present in the final product.
Bioethanol lignin based carbonaceous powder was prepared using carbonization and ball milling optimization to provide a material that may be used as a substitute to carbon black. The resulting carbon powder showed greater surface area and thermal conductivity to carbon black with particle sizes around 1 micrometer. The carbonized ball milled lignin was then compared against commercial carbon black as filler in the formation of thermoplastic composites. The lignin based carbon filler was able to perform similarly to carbon black by increasing the thermal conductivity but no enhancement in the electrical conductivity was evident for the biobased filler.
It is well established that the addition of solid particles that absorb light across ultra-violet (UV) wavelengths can improve the environmental durability of plastics. Thermoplastic polyester elastomers are sensitive to UV degradation in both exterior and interior applications. This paper describes an experimental evaluation of the improvement in UV performance of a polyester elastomer, Hytrel?, with the incorporation of a conventional chemical UV stabilizer along with different UV absorbing or scattering solid fillers. A rapid screening method is described that measures mechanical elongational properties as a function of UV exposure time. The results show that the particle type and size, the dispersion quality and melt compounding conditions affect UV durability.
Polylactic acid (PLA) was blended with corn zein and various compatibilizers in order to study a composite with potentially improved barrier and thermal properties. Thermogravimetric analysis (TGA) was used to characterize the thermal stability of the composites in comparison to pure PLA, and it was determined that the thermal properties, specifically the onset degradation temperature and rate of degradation of PLA and its composites are extremely dependant on the test method utilized. In this study pure Natureworks 2002D PLA displayed onset degradation temperatures ranging from 306øC to 360øC, depending on whether or not an isothermal hold was incorporated into the TGA method. Rather than improving the thermal stability of the PLA, the addition of corn zein catalyzed the reaction, increasing the rate of degradation, and decreasing the onset degradation temperature.
Biobased plastics are becoming viable alternatives to petroleum-based plastics because they decrease dependence on petroleum derivatives and tend to be more environmentally friendly. Raw materials such as soy flour are widely available, low cost, lightweight, and can have high strength. In this study, soy flour was utilized as a filler in thermoplastic elastomer composites. Because weak interfacial adhesion between the soy flour and the elastomer and low water resistance pose challenges, a surface pretreatment, acetylation, was investigated for composites with soy flour concentrations of 10 wt%, 15 wt% and 20 wt%. Previous studies of the mechanical properties of these composites at 10 wt% determined that acetylation resulted in ultimate strength comparable to that of the pure elastomer. In this study, the chemical pathways of the reaction were verified and the thermo-mechanical properties characterized. Interfacial adhesion was characterized through scanning electron microscopy (SEM); the study determined that the acetylation reaction increased interfacial adhesion as indicated by smaller particle sizes and less agglomeration. Thermal properties were determined though thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Acetylation reduced the intake of water by the soy flour, thus increasing the thermal stability of the composites. Increased thermal stability was indicated by a rise in decomposition temperature.
In order to design and manufacture natural fiber-polymer composites as structural components in existing and novel technological applications, the long term viscoelastic behavior of the materials must be understood. In order to do that, the time?temperature superposition principle (TTSP), is used to predict long-term viscoelastic behavior from short-term experimental data. Dynamic?mechanical analysis (DMA), was used to study the viscoelastic properties of composites made from fique mats and low-density polyethylene?aluminium (LDPE?Al) obtained from recycled long-life Tetra Pak packages. This paper reviews the effect in using Chemical treatments such as alkalinization with NaOH, silanization, and polyethylene impregnation treatments for composites, understanding the interaction mechanisms between natural fibers and the LDPE-Al; and presents the effects of treatments on the viscoelastic behavior. Fractographic evaluations in the scanning electron microscope (SEM) confirm the quantitative characterization obtained from DMA.
Antistatic/dust and ESD management demands are increasing at electronics relevant use plastics especially semiconductor handling area. Transparent performance also needed at specific area because confirm able inside without opening box to minimize contamination from outside. Electrical conductive carbon filler is one option, but it?s tough to achieve both these performance. On the other hand, primary antistatic agents like a surfactant type are questioned for their duration of the antistatic performance. This paper discusses refractive index matched transparent antistatic polycarbonate and polyester blends that offer transparency, sustainable antistatic performance, and cleanliness (lower out gassing, leachable ions).
Nylon is widely used in many applications. At the 2013 ANTEC in Cincinnati, our paper covered the results obtained with compounding primarily recycled nylon with the addition of small quantities of alternating ethylene and maleic anhydride ZeMac? copolymers and specific property improvements for applications in injection molded compounds. The resulting compounds have performance that can match or exceed prime virgin nylon at 30-50% cost savings. At the 2014 ANTEC in Las Vegas, our paper covered the performance enhancements to provide several advantages for upgrading virgin nylon such as increasing relative viscosity for improved melt strength and the unique improvements obtained in impact-modified nylon-6 and nylon-6,6 by reducing the negative impact of traditional impact modifiers by offering synergistic set of properties. This current paper will cover how using the unique chemistry of these copolymer products can reduce costs in nylon compounds and still meet performance specifications.
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