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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Tensile Property Changes in Commercial Biopolymer Products Based on Environmental Conditons
The current trend towards sustainability has created new interest in biodegradable plastics. While many investigations have examined the behavior of biodegradable plastics, the changes in properties that may occur during use have not been fully developed. The mechanical properties of seven types of biodegradable plastics were analyzed. In addition, the properties of polystyrene (PS) used in similar applications were examined. The effects of UV exposure, humidity and accelerated aging on the mechanical properties were studied. In general, the strength of several biopolymers was less than that of PS. Polylactic acid and wheatstraw had a higher strength than PS. The properties of biodegradable plastics deteriorated significantly upon exposure to UV radiation and humidity. Accelerated aging data indicates that after 6 months under ambient conditions, the biodegradable plastics also have a reduction in strength and modulus. Additional improvements may be necessary to resist environmental effects so that biopolymers can be effective replacements for traditional plastics.
Novel CuNW/VDF Nanocomposite for Charge Storage: Comparison of its Dielectric Properties with MWCNT/PVDF Nanocomposite
Multi-walled carbon nanotubes (MWCNT)/ poly(vinylidene fluoride) (PVDF) and copper nanowires (CuNW) / PVDF nanocomposites with filler content ranging from 0.4 to 1.5 v% were prepared by the miscible solvent mixing and precipitation method followed by melt compression. The electrical and dielectric properties of MWCNT/PVDF and CuNW/PVDF nanocomposites were then compared; it was observed that the CuNW/PVDF nanocomposites had the highest real permittivity combined with a low dissipation factor (tan ?) due the presence of a thin layer of oxidation in the CuNW surfaces, which works preventing the direct contact between the conductive fillers.
New Biopolymer Alloys: Plexiglas® Rnew for Durable Applications
Altuglas International, a division of Arkema Inc. has recently developed Plexiglas® Rnew acrylics, a new technology based on poly(methyl methacrylate)/biopolymer blends. These resins, containing ? 25% renewable carbon, are in line with Arkema’s commitment to sustainability while offering exceptional performance for transparent or opaque durable goods in medical, transportation, building and construction, and consumer applications. As opposed to many green plastics, where material performance must be sacrificed for bio-content, this technology allows for impact properties, chemical resistance, and processability far superior to traditional acrylic products.
High Recycle Content PBT/PC Product Development
PBT/PC blends provide an excellent balance of chemical resistance, mechanical strength (especially at low temperature), and processability for a wide range of applications. Recently, appliance applications started to demand more sustainable, environmentally-friendly and green materials without sacrificing any properties for their new generation products. To respond to this market requirement, a high recycle content PBT/PC blend with excellent chemical resistance properties, good FR performance, and great mechanical properties was developed. The use of a high recycle based PBT/PC blend is the key to opening a new door to the more sustainable and green world for future appliance applications.
Hydroxyl-Functionalized Polypropylenes - Crystallinity and Structure
In search of improved polymeric materials for capacitors, OH-modified polypropylenes are evaluated. Thermal and structural aspects are reported as to establish their influence in voltage breakdown characteristics. In industry polypropylenes films are biaxially oriented to improve their voltage breakdown, however the orientation of polypropylenes has to be done in partially molten state. Within these semimolten states other processes are also observed, mainly re-crystallization. The presence of intermolecular H-bonding between the OH groups affects polypropylene structure and its properties e.g. thermal. Extended annealing at various crystallization temperatures of PPOH materials results in recrystallizations processes that change the thickness of the lamellae, but not their ?-monoclinic crystal structure. The percent crystallinity decreases with increasing crystallization temperatures, however the process of annealing increases total amount of crystalline fraction in the material, which might lead to increased brittleness. Annealing leads to formation of well observed kebab-like lamellae structure.
Assessment of Polybutylene Plumbing Installation after 18 Years of Service
An analysis was undertaken to assess the condition of polybutylene (PB) pipes that had been in service for 18 years. The building owners were concerned about the future reliability of the piping system given some of the previous publicity on the past concerning PB piping systems. The pipes were inspected and tested, showing that the 18-year-old pipes still met the ASTM specification requirements for new PB pipe and exhibited only superficial oxidation due to water service exposure. The PB pipe samples were also pressure tested for burst and long-term stress rupture properties and exhibited equal or better performance compared to new PB pipe.
High Temperature Shape Memory Polymer
A high switching temperature shape memory polymer system was developed from metal salts of sulfonated PEEK ionomer and ionomer/fatty acid salt compounds. The metal salts of sulfonated PEEK (M-SPEEK) show moderate shape memory behavior, but compounds show promising shape memory behavior. The compounds were prepared from the mixture of sulfonated polyether ether ketone (PEEK) metal salts (sodium and zinc) and low molar mass crystalline fatty acid salt sodium oleate (NaOl). Ionic clusters formed by the interactions of ionic groups provided a permanent cross-link network and strong dipolar interactions between the ionomer and a dispersed phase of crystalline NaOl provided the temporary network. A temporary shape was achieved and fixed by deforming the material above the melting temperature (Tm) of NaOl and then cooling under stress to below Tm. The permanent shape was recovered by reheating the material above Tm without applying stress. Shape fixing efficiency of 96% was achieved and shape recovery reached 100%. Triple shape memory behavior was observed in M-SPEEK/NaOl systems which have two thermal transition mechanisms.
Thermal endurance and the thermal degradation kinetics of a Polypropylene/wood composite in an inert and oxidative atmospheres
A commercial wood polypropylene composite was developed using a twin screw extruder. Thermal endurance of the compound was assessed under oxidative and inert atmospheres by using conventional thermogravimetric analysis; the thermal endurance of PP is higher in an inert atmosphere, while the thermal endurance of wood powder is very similar in both atmospheres. In contrast, the thermal endurance of the wood polypropylene composite is higher in air. The activation energy results showed that the values obtained by conventional TGA had the same order of magnitude as values obtained from Modulated TGA. Fourier transformed infrared, electron microscopy was done to evaluate the chemical and physical interaction of materials in the final compound.
Optimizing Pipe Extrusion Dies Using CFD Simulation
The extrusion of polyolefin pipes suffers degradation due to mechanical design problems of the extrusion die that is commonly used. This study uses numerical and computational approaches to detect problematic areas in the die geometry. Simulations show that in the conventional die there are areas of stagnation and recirculation of the melt flow, resulting in greater residence times, one of the main causes of degradation. This study introduces the use of novel profiles, which reduce stagnant flow regions, recirculation events, and can optimize the pipe extrusion process. Additionally, this study illustrates a methodology based on residence time distribution (RTD), a parameter that can be applied in optimization of the tooling and equipment in extrusion processes.
Effect of Poly(Butylene Adipate-Co-Terephthalate) Contents on Crystallization and Mechanical Properties of Polymer Blends of Poly(Lactic Acid) and Poly[(Butylene Succinate)-Co-Adipate]
The effect of poly(butylene adipate-co-terephthalate) (PBAT) contents on crystallization and mechanical properties of poly(lactic acid) (PLA) and poly(butylene succinate-co-adipate) (PBSA) blend was studied. PLA and PBSA were blended in a twin screw extruder, which incorporated PBAT as a ternary component in PLA/PBSA blend. The ratio of PLA/PBSA was set at 80/20. The contents of PBAT were varied from 0 to 50 wt%. The thermal properties and crystallization behavior of PLA/PBSA/PBAT blends were analyzed by differential scanning calorimetry. The effect of PBAT contents on non-isothermal crystallization kinetic of the composites was investigated by using Avrami equation. Tensile modulus and tensile strength of the PLA/PBSA blends decreased when increasing PBAT contents. It can be noted that the addition of 20 wt% PBAT showed the maximum impact performance of the PLA/PBSA blends.
New generation of potable Noryl resin grades for Fluid Engineering
New generation of potable water certified Noryl™ grades for Fluid Engineering Noryl™ resins include blends containing Polyphenylene Ether (PPE) and crystal clear Polystyrene (ccPS) and/or High Impact Polystyrene (HIPS). Noryl™ resin has been used in fluid engineering applications already since 1969 in various applications (water meter housings, impellers, faucets, pumps, etc.) due to its excellent hydrolytic stability and low water absorption. Over the years, the applications requirements changed, new applications evolved, and changes in legislation happened (food contact & drinking water). For a high demanding application (hydroblock or manifold), Noryl™ resin grade GFN1630V has been successfully used. However due to changes in legislation a re-design was needed in order to be compliant with future food contact and drinking water requirements. The development and more specifically the testing needed to come to the optimal formulation selection will be discussed.
A Novel Continuous Kynar® PVDF Foam Concentrate and Application Developments
Kynar® PVDF and Kynar Flex® PVDF have long been used for many extrusion applications. The need for lighter weight, more flexible product has been of interest for some time, but the lack of the ability to foam PVDF for continuous products has always been an issue. Several batch processes for producing PVDF foam articles currently exist, but filling the need for continuous articles such as plenum rated wire, tube, pipe, film, and stock shapes has continued to be a challenge. Research organizations and industry experts have made several failed attempts to be able to develop a robust foaming mechanism and process for PVDF resins. Finally, Arkema has developed a suitable chemical foam concentrate as well as a robust processing method for many continuous Kynar® PVDF applications of infinite length.
Shape-Memory Behavior of a Polyethylene-Based Carboxylate Ionomer and Compounds Containing Zinc Stearate
Shape memory polymers (SMP) are materials that can change shape when exposed to an external stimulus, such as temperature. Thermally-actuated shape memory polymers can be deformed when heated above a critical temperature (Tc) of a reversible network, and then fixed into a temporary shape when cooled down under stress below Tc. When the material is reheated above Tc, the reversible network disappears and material recovers its original, permanent shape. The permanent shape of an SMP can be provided by chemical crosslinks or physical crosslinks that persist above Tc. The reversible, temporary network is created by physical crosslinks or hard domains that vanish above Tc. The unique properties of SMPs can be used in various applications, such as intelligent packaging, reconfigurable tooling, aerospace systems, biomedical devices, artificial muscles and self-deployable devices. Shape memory polymers were prepared from Surlyn® 9520, an poly(ethylene-co-methacrylic acid) ionomer and its blends with Zinc Stearate (ZnSt). Surlyn® 9520 is a semicrystalline ionomer with a broad melting point in the range 60-100 °C, physical cross-links in the ionomer due to interchain ionic interactions provided a “permanent” cross-linked network, while its crystals provided a temporary network. Although the ionic associations within the ionomer can be used as the permanent network, the critical role of the ionomer is to facilitate dispersion of the FAS and to provide a complementary functionality to the matrix polymer that stabilizes the FAS dispersion and develops the strong intermolecular interactions. Broad melting point due to the different size of crystals in the ionomer that melt at different temperature allowed demonstrating the tenability of shape memory effect in this ionomer. A separate route of achieving shape memory properties of the samples by blending the ionomer with ZnSt was shown. The strong dipolar interactions between the ionomer and a dispersed phase of crystalline ZnSt
Rotational Molding Cycle Reduction by Preheating the Mold and the Polymer Powder
Rotational molding is the preferred and most appropriate method for making large, hollow plastic parts. Its primary advantages over other methods, such as blow molding and twin sheet thermoforming, are that parts are practically unlimited in size and are relatively stress free, since material is not forced into shape. One of the main disadvantages of rotational molding is long cycle times. The objective of this study was to explore methods of reducing the overall cycle time, with an emphasis on reducing oven cycle time. A series of cycles were run to investigate the effect of preheating, mold and polymer powder, on oven time using the mold internal air temperature, an indicator of oven cycle completion time. An overall cycle time reduction will ultimately lower production and product costs, as well as reduce energy consumption.
Effect of part thickness on the potential to induce cold crystallinity in nylon 6,6 injection molded samples
Tensile bars of two different thicknesses were injection molded from Nylon 6,6 under controlled conditions and DMA results compared. Early analysis indicates that cold crystallization can be induced for improved mechanical properties on the 2mm thick samples, but not for the 4mm samples. This is due to the more prominent shear-induced orientation layers inherent in the thinner sample re-orienting during the annealing process. Results indicate there may be applications where the crystalline distribution through the thickness of a part may be critical to the plastic performance in cyclic or thermal load bearing applications.
Sustainable In-Machine Mold Cleaning and Part Deburring & Deflashing Using Dry Ice - Changing the Game Rules with CO2
For plastic processors there is a great demand to increase the productivity of their equipment and the quality of their parts, while maintaining healthy margins. This can be a balancing act between using the most effective technology while working within a shrinking budget. This paper discusses the advantages of dry ice blasting as a replacement for solvent and/or mechanical cleaning for the removal of contaminants from tooling as well as its use to deburr and deflash plastic parts. While the principles discussed herein are applicable to multiple plastics processes (BM, Ext., etc.), the focus of this paper will be on injection molding and the various steel and aluminum mold substrates commonly used. The reader will achieve a benchmark understanding of the role and relevance of dry ice in mold cleaning, part deburring & deflashing and its impact on product quality, production cost, production efficiencies, worker safety and health and environmental responsibility. Research from several industry case studies will be discussed. The results confirm that dry ice cleaning can remove contaminant layers from various common mold metals and is a good alternative to other commonly used manual, abrasive methods as well as successfully deburr and deflash plastic parts.
Bridging the Gap: Using Injection Molding Simulation to Determine Realistic Plastic Tolerances
Dimensions on plastic parts are affected by material shrinkage and can limit the dimensional stability of a final product. Incorporating injection molding simulation into the design and manufacturing process allows companies to better determine the dimensional changes that occur due to molding. Moldflow, an injection molding simulation program, was used to import CAD geometry and select processing conditions to predict part shrinkage. These shrinkage results were compared to measured molded parts to determine variations in dimensions. By understanding the correlation between processing conditions and molded part dimensions, manufacturers can control the sensitivity of the molding process and the ability to maintain products within specifications.
Influence of exfoliated carbon nanotubes on crystal structure and tensile properties of polypropylene
The objective of this work is to investigate the microstructural mechanisms responsible for the observed remarkable increase in modulus and strength of polypropylene (PP) containing only trace amounts of multi-walled carbon nanotubes (MWCNTs). The functionalized MWCNTs were individually dispersed in commercial polypropylene matrix by using our novel nanoplatelet-assisted dispersion approach, followed by compatibilization of MWCNT in a small amount of stabilizing surfactant. We also report on the morphology and dynamic mechanical properties, and propose a novel mechanism for reinforcement of thermoplastic materials with individual MWCNTs.
Study of Interfacial Interactions in Exfoliated Graphite Nanoplatelets/Polyamide 12 Nanocomposites
The interfacial nano-reinforcement -polymer interactions in polymer nanocomposites (PNCs) are key in fabrication of PNCs with engineered properties. Our study showed the presence of an immobilized layer or interphase around nano-reinforcements and investigated possible correlations between interfacial interactions and macro-scale properties of PNCs. Polyamide 12 (PA12) based PNCs reinforced with 0-15 wt% of exfoliated graphite nanoplatelets (xGnPs) were fabricated. The results indicated occurrence of attractive interactions at the interface of xGnP and polymer leading to formation of a stiff interphase a few tens of nanometers thick. The altered dynamics of the immobilized layer was suggested to develop a dominant secondary mechanism contributing to the macroscopic properties of the PNCs.
UV Monocoat: Ad Advanced Coating Technology for Consumer Electronics
Surface coatings on plastic substrates with excellent physical performance, low application cost, and minimum environmental impact are highly desirable for various commercial applications. Here we describe PPG’s ultraviolet (UV) monocoat technology for consumer electronics, which afforded both protection and decoration of plastic substrates with a single-layer colored coating system. Studies demonstrated that UV monocoat applied on plastic computer and cellphone parts successfully met or exceeded customers’ specifications, showing good adhesion to plastic substrates, excellent abrasion and scratch resistance, good chemical resistance, and high weathering stability. UV monocoat also enabled a variety of colors with a wide range of gloss for decoration of plastic substrates. In addition, UV monocoat uniquely combined a single-layer design with UV cure technology, which significantly increased on-line coating capacity and efficiency and dramatically reduced application cost and environmental impact.
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