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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Three Trends in Healthcare Adhesives
With an aging global population growing, the demand for new healthcare products and telehealth systems will increase. The FDA aims to advance innovation and development in digital health while ensuring patient safety and effectiveness. Adhesives are critical in the new remote monitoring products, such as the small wearable devices that stick to skin. In addition, surgical adhesives are replacing stitches, and robotic surgical systems are rising. With healthcare adhesives, there are additional challenges in safety, performance, biocompatibility ISO 10993, and cost requirements. This paper reviews three healthcare adhesive trends: (1) topical skin adhesive patches, (2) tissue adhesives, and (3) medical device assembly and equipment adhesives.
Adhesion of Overmolded TPE to FR-PC/ABS: Effect of TPE Properties and Substrate Color Recipe
Various grades of Thermoplastic Elastomer (TPE) were overmolded onto a FR-PC/ABS blend prepared with several different color recipes and tested for adhesion. All combinations prepared exhibited adhesive failure with a standardized peel test, yet showed relatively high average peak peel forces that ranged from 3.74-4.07 N/mm, which agreed well with literature values. Different color recipes for the substrate had no discernable effect on peel forces. Two-step overmolding of TPE using pre-molded (and therefore conditioned) substrates gave no significant difference to those prepared with direct 2-shot overmolding.
Effect of Molding Parameters on Orientation and Tensile Properties of Polycarbonate
The tensile properties of two different molecular weight polycarbonates were examined in relation to injection-molding conditions, such as low and high temperatures & speeds (affecting injection pressures), that were beyond those recommended by the supplier. We found conditions that prompted higher injection pressures led to decreases in tensile elongation-at-break, with more significant decreases for higher molecular weight (and high viscosity) PC. Examination of molded samples under polarized light suggested higher degrees of molded-in stress along the flow length as an important contributor to the changes in elongation at break. Additionally, corresponding to the elongation at break, the onset of strain hardening decreased under injection molding conditions that produced higher injection pressures.
Effect of Rubber Surface Treatment on the Properties of Rotomolded Thermoplastic Elastomers
Thermoplastic elastomers (TPE) are a combination of a rubber and a thermoplastic to create a recyclable blend combining the properties of both resins. The objective of this work is to produce and characterize rotomolded parts based on polyamide 6 (PA6) as the matrix and recycled ground tire rubber (GTR) as the dispersed phase. In order to improve the adhesion between PA6 and GTR, and consequently the mechanical properties of the resulting TPE, a treatment with formic acid was used on the GTR surface. All the samples were initially mixed via dry-blending using 5 and 10% wt. of GTR and then rotomolded. For these concentrations, successful rotomolded parts were produced to report on their morphological and mechanical properties. The results show that increasing the GTR content led to lower tensile modulus and tensile strength, but higher elongation at break and impact strength compared to the neat matrix.
Polypropylene/Ground Tire Rubber (PP/GTR) Composites Produced Via Rotational Molding
In this work, polypropylene (PP) was dry-blended with ground tire rubber (GTR) to produce composites by rotational molding. In particular, the effect of GTR content was investigated to modify the mechanical properties of the PP matrix. Each compound was characterized via morphology, density and mechanical properties (tensile, flexural and impact). As expected, the results showed that all the mechanical properties decreased with increasing GTR concentration due to its low modulus and strength. Also, the crosslinked structure of the GTR particles is believed to limit the interfacial PP-GTR interaction, thus also limiting mechanical stress transfer.
Superhydrophobic Encapsulants for FHE Devices
Flexible Hybrid Electronics (FHE) offer benefits for a wide range of applications, such as healthcare wearables, smart layer-based integrated sensor networks, soft robotics, and digital microcontroller circuits. It is critical to developing flexible and stretchable encapsulants for FHE devices to protect them from environmental conditions. Encapsulants for advanced FHE devices require innovative materials and processes to ensure the microchips' physical/chemical protection without compromising the stretch or flex characteristics. Consequently, this work is focused on developing a superhydrophobic (SH) coating that can be spray-coated on FHE device for encapsulation. The SH coating is based on commercial conformal acrylic resin with alkyl treated SiO2 nanoparticles that provide both the roughness and hydrophobic chemistry to be applied to alumina and treated polyimide. The resulted coatings possess low surface energy due to the formation of a micro/nano tailored hierarchical structure and hydrophobic moieties. The study investigates the durability of the superhydrophobic coatings using the Peel Test, Flexibility Test, Scratch Test, and Hardness Test on the two substrates. Experimental results indicated that the mechanical durability was improved when applying two coating layers with a mixing time of 1 hour first and then ¬Ω hour withstanding more than 8 peels. Furthermore, the aluminum and polyimide substrates' Scratching indicates that the coating peels off completely with Àú0.5 [N] andÀú4 [N], respectively. The Pencil hardness test results suggest that the polyimide substrate starts to fail at '5H' hardness, and the Alumina coating starts to fail at ‚ÄòH‚Äô hardness. The final coatings show good durability overall and long shelflife stability.
Chemical Resistance Testing of Polycarbonates and Blends With Hospital Disinfectants and Cleaners
We tested an array of hospital surface disinfectants and cleaners for compatibility with several polycarbonate-based thermoplastic materials commonly used in healthcare equipment. To assess compatibility, we exposed tensile specimens to cleaners while under flexural strain, and then checked for cracking and tensile property retention. The results illustrate which cleaners are the harshest and which materials are the most chemically resistant. We also observed that periodic wiping and drying is frequently more damaging than the traditional test method of continuous wet exposure.
Development of Innovative Biocidal Nanoparticles For Use In Plastics Technology
Increased demands on high-end materials focus the development on new functionalities such as biocidal effects, which are made possible by property changes in the nanoscale range of existing materials or by a combination of different material classes. Therefore nanoparticles, based on transition metal oxides have been synthesized in order to reach biocidal properties on plastic part surfaces. The influence of the nanoparticles on the thermal and mechanical properties have been characterized as well as the biocidal properties of the plastic part surfaces and of the nanoparticles itself.
Effect of Photoinitiator Concentration and Curing Time on Soybean Polyethylene Glycol Resins
Bioprinting, a subset of additive manufacturing, utilizes bioinks, which is a combination of biomaterials and live cells, to produce functional tissue. Soybean oil is a plant polymer with promising biomaterial properties for development as a bioink. Soybean oil is low cost, has excellent biodegradation, biocompatibility and low immunogenicity.Additionally, suboptimal soybean properties such as mechanical and bioactive properties can be altered and improved when combined with other polymers. The curing of resins formulated from a combination of soybean oil epoxidized acrylate and poly(ethylene glycol) diacrylate was investigated with different concentrations of the photoinitiator diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide/2-hydroxy-2-methylpropiophenone, blend (DPH) and at different curing times. Visual observations of the cured resins indicated that as the photoinitiator concentration and curing time were varied, the resins exhibited changes in flexibility and rigidity / brittleness.
Long- and Short-Term Tensile Strength and Morphology of Joined Beta-Nucleated Polypropylene Parts
This paper presents the results of static short-term and long-term tensile tests for beta-nucleated joined polypropylene samples by the hot plate welding process. In the present study different dimensionless joining displacements are accounted for. The results show that high short-term tensile strength does not directly transfer to high long-term tensile strength. The morphology of the weld seam in the joined samples is examined by means of transmitted and reflected light microscopy. For the dimensionless joining displacements of 0.75 and 0.95, stretched spherulites are obtained. X-Ray diffraction can be used as a tool for qualitative and quantitative analysis and eventually for differentiation of samples of various joining displacements.
Modeling of Heat Generation in Spin Welding
Spin welding is a common joining process for plastic parts with circular joints such as insulated cups and bowls, filter housings, and valves. In this process, heat is developed from surface friction as one part is revolved about the axis of the joint, resulting in a high linear speed. Finite element analysis (FEA) of the process can provide insight into potential mechanical deformation or failure under load that may compromise the weld, as well as aid in determining proper process parameters to achieve sufficient heating for a good weld. In this work, an approach to predict the weld temperature has been investigated and compared to measured results.
The Effect of Argon Plasma Irradiation On 3D Scaffolds For Bone Tissue Engineering
Tissue engineering using 3D scaffolds is an alternative to bone repair techniques that are currently used, such as autografts or allografts for bone non-union. Plasma irradiation is used as a sterilization method and can alter the surface topography of the scaffolds. We have prepared 3D scaffolds composed of poly(lactic-co-glycolic)acid (PLGA) and nanohydroxyapatite (nHA) using thermally– induced phase separation (TIPS) and 3D-plotting (3DP) techniques. We have also performed experiments to study murine stem cell adhesion to scaffolds that have been plasma irradiated. The scaffolds that were plasma irradiated with argon gas had ~140% more cell adhesion compared to untreated scaffolds.
Windows of Opportunities for Single Site Catalyst
What makes company A produce 50,000 tons/year more of the same PE or PP than company B at the same cost? Catalyst, catalyst and catalyst. Very quietly, catalyst research has brought revolution in the plastics industry. So-called single-site catalysts (many of which are metallocenes) are closely guarded secret of alpha-olefin "big guys". A single metal atom held between two carbon rings builds metallocenes. They might look naive but provide greater control over molecular chain length and structure of polyolefins. These polymers are stronger, purer, and clearer. Upon utilizing these catalysts, material suppliers can accurately design tailor-made resins for specific applications.
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