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.
This paper covers a failure analysis of a cross-linked polyethylene (PEX) hot and cold water plumbing system that utilized plastic insert fittings that were fastened with stainless steel clamp rings. The failed fittings exhibited features that led several different investigators to associate the failures with fatigue and slow crack growth. Our examination of the fractures indicated that the failures were due to high stress that caused crazing and subsequent fast fracture of the fittings. Environmental Stress Cracking (ESC) may also have been involved as a contributor to the failures.
Epoxy composites offer high performance and proven reliability in many demanding applications including components for aerospace and wind turbine blades. While in operation, these components are subjected to repeated cyclic loadings that result in material fatigue. For example, wind turbine blades are subjected to significant stresses from their movement, wind and other environmental factors such as temperature cycling and humidity. The expected life of a composite structure is based partially on the resistance of the materials utilized to fatigue failures.
This paper evaluates the potential use of biodegradable polymer for fuel system components by considering operating conditions. Organic liquid diffusion into biodegradable polymer was observed by fuel immersion at various temperatures ranging from 5 to 50§C until the equilibrium condition was achieved. During the immersion time, mass uptake and length swelling were recorded periodically. The data were plotted for diffusion coefficient calculation at each temperature. Changes in mechanical properties were also investigated through tensile, flexural and impact testing. The results resemble the impact of gasoline absorption on biodegradable polymers when used for the under-hood components of a vehicle.
The ability to be recycled is an important attribute for many plastics. By melting and reprocessing thermoplastics for re-use the carbon footprint can typically be reduced compared to the use of virgin materials. The benefits of incorporating recycle content into new and existing applications, however, must be tempered by the reality that recycled plastics may not have the same performance as virgin materials due to either 1) degradation by weathering/aging, 2) contamination, or 3) thermo-mechanical degradation from re-processing. To minimize these effects, it is important to understand the benefits of utilizing impact modifiers and compatibilizers.
Carbon dioxide (CO2) and nitrogen (N2) are environmental-friendly blowing agents, but they pose various technical challenges to plastic foaming industries in producing high quality foams with uniform cell morphologies. Previous studies demonstrated improved foam morphologies when CO2/N2 blends were used, but the fundamental mechanisms of such foaming processes are not thoroughly understood. This study examines the foaming behavior of polystyrene (PS) blown with CO2/N2 blends by observing their foaming processes in situ.
Presented in this paper are the preliminary results from an experimental study on the use of rock, fines* which is mainly silicon dioxide as a filler in the rotationally moulded polyethylene products. The rock fines are a waste product from the Quarrying industry. Additive levels of up to 40% by weight were studied. Samples were made with and without a compatibilizer. It was found that acceptable parts were produced at these levels. The mechanical properties of the parts were tested and showed an increase in tensile modulus but a decrease in impact properties.
The wide variety of biomedical applications employing biodegradable polymers requires a similarly wide range of biodegradation properties. In this study, a dynamic melt manipulation technique in injection molding has been investigated as a low cost, high volume manufacturing alternative to respond these requirements. The technique utilizes an additional oscillatory motion during injection molding to induce molecular alignment of polymer molecules in the final product. Preliminary experimental results have indicated that biodegradation process is dependent on these orientation levels and therefore polymeric medical devices with different degradation characteristics can be obtained simply by changing the manufacturing parameters.
One of the most environmentally friendly energy generation methods is wind power. In order to compete favorably with the cost of traditional energy generation methods, the wingspan needs to increase from current dimensions. For this to occur, taking advantage of new material developments in nano-reinforced composites is essential. The use nanoparticles have shown improvement in mechanical properties of FRPC. Understanding the manufacturability of these processes is critical, especially during VARTM. Understanding the factors affecting the flow through porous media and the inherent material properties, such as permeability and viscosity, of these nano-enhanced FPRC was the objective herein.
The properties of six biodegradable commercial plastic bags, including BioBag, Flushdoggy, Green Genius, Oxobiodegradable, Rascodog, and World Centric, were examined. Most of the bags exhibited mechanical properties similar to traditional bags. One bag that had extensively higher properties was the Flushdoggy bag, which is based on PVA. All the bags generally start to degrade thermally at around 400C. Exposure to UV light did not have much of an effect on tensile properties. UV radiation, moisture, and weathering all had little effect on thermal degradation. Oxo-biodegrable and Flushdoggy became especially brittle after accelerated aging, although Flushdoggy still exhibited strong tensile properties.
New family of ENH flame retardant PBT (polybutylene terephthalate) and PBT/PC(polycarbonate) thermoplastic resins developed is aimed at helping electrical/electronics (E/E) manufacturers and suppliers comply with regulations restricting use and disposal of hazardous substances. The non-chlorinated, non-brominated FR PBT and PBT/PC products deliver similar mechanical, physical, thermal and flame retardant performance compared with their brominated FR based counterparts. Some of those resin properties will be discussed in this publication.
Two renewable copolymers, poly(trimethylene malonate) (PTM) and poly(trimethylene itaconate) (PTI), have been produced with ester bonds incorporated into the polymer backbone to facilitate hydrolytic and/or enzymatic degradation. A hydrolytic degradation study of these renewable polymers in aqueous solutions adjusted to pH values is described. Final weight loss varied from 20 to 37 wt% for PTM and from 7 to 21 wt% for PTI as a function of aging time and initial solution pH. Degraded samples were characterized by FTIR, GPC, DSC, and TGA. PTI showed a slower degradation rate than PTM.
To reduce manufacturing costs and address environmental issues, coatings free Mold-In-Color plastics are now replacing coated plastics. This paper will explore the physical property retention / weathering performance of various Mold-In-Color plastics used for exterior trim. Exposed specimens are analyzed for their change in physical properties then analyzed for change in surface chemistry via infrared spectroscopy and surface topography. It is concluded that some plastics containing styrene experience a change in physical properties and surface chemistry upon UV expose while other materials like PMMA acrylic retain their original performance.
Highly expanded polyolefin foam was made flame-retardant with the use of an environmentally friendly phosphorous flame retardant. An aqueous solution of a derivative of carboxylic acid of phenylphosphonic acid was externally applied to already-made partially-open-celled foam to achieve desired flame-retardant foam. An effective flame retardant level as low as 0.1 pars per one hundred parts of resin provided self-extinguishing foam. The compound could also be directly fed in the extrusion process. This finding opens an avenue to achieving a low-cost thermal insulation material from polypropylene.
Polypropylene carbonate (PPC) is an amorphous polymer made by alternating copolymerization of carbon dioxide and propylene oxide. SK Energy developed its own proprietary technology with a highly active catalyst for this polymerization and has begun to produce PPC in its continuous process type pilot plant since late 2008 with a trade name GreenPolTM. In this paper, we are describing the typical properties of PPC such as general physical properties, barrier properties, thermal and UV stability, and smoke density along with some rheological properties.
Use of recycled thermoplastic polymer composites for manufacturing and evaluation of structural products as a sustainable solution is discussed in this paper. Durability (aging) evaluations of those polymers have also been carried out to predict their service life. Specifically, ABS polymers were reinforced with 4%, 7% and 12% fiber volume fractions of bi-directional glass fabric (fabric density: 407 gm/sq. mtr. or 12 oz per sq. yard) and were evaluated. Research results indicate the significant potential of recycled polymer composites for different applications with the use of continuous glass fabrics.
Ethylene ionomers, such as Surlyn from DuPont, have long been used as packaging sealants because of their good mechanical properties and formability combined with excellent seal strength over a wide sealing temperature range, seal integrity in the presence of contamination, and hot tack. Ionomers can be modified with biosourced additives, such as fatty acids to modify their mechanical and barrier properties. In this paper we discuss blending these recently developed ionomers with commercially available ethylene copolymers to achieve films containing 20% -40% renewable content having a good balance of sealant and mechanical properties.
A series of poly(1,9-nonamethylene adipamide-co-1,9-nonamethylene terephthalamide) copolymers were produced using melt polymerization and the thermal properties and crystal structure characterized. The results obtained confirmed that the copolymers exhibit isomorphism. As expected, glass transition temperature and the apparent melting temperature increased with increasing terephthalmide content. Using the difference in the apparent melting temperature to the crystallization temperature as a measure of relative crystallization rate, it was observed that crystallization rate decreased as the terephthalamide content of the copolymer was increased from 0 to 50 mole percent but then sharply increased when increased beyond 50 mole percent.
Recycled poly(ethylene terephthalate) (RPET) chain extender (CE) and nanoclay were prepared via conventional and microcellular injection molding processes. The effects of CE loading levels and the simultaneous addition of nanoclay on the thermal and mechanical properties and cell morphology of the microcellular components were noted. The addition of 1.3 wt% CE enhanced the tensile properties and viscosity of RPET. The higher amount of CE (at 3 wt%) enhanced the viscosity, but margin of improvement in mechanical properties diminished. While the solid RPET and CE blends were fairly ductile, the samples with nanoclay and all microcellular specimens showed brittle fractural behavior.
Recycling of unfilled and reinforced poly (phenylene ether) (PPE) based thermoplastic elastomers (TPEs) was studied in detail. Improvement in mechanical properties upon recycling of the unfilled quaternary blend comprising of styrene-ethylene-butyllene-styrene (SEBS)/ethylene vinyl acetate (EVA)/PPE-PS (polystyrene) was correlated with the formation of crosslinked network. PPE based TPEs have been reinforced by incorporating nanofillers and with the formation of crosslinkinked TPEs or thermoplastic vulcanizates (TPVs). This study also provided an in-depth conceptual understanding of the recycle behavior PPE based TPE behavior upon reinforcement with silica nanoparticles and silica sol-gel precursors.
Environmental stress crack resistance (ESCR) is a critical mechanical property for polyethylene in injection and rotational molding applications. Based on a very well characterized matrix of materials with widely varying densities and melt index, we have looked at broad orthogonal composition distribution (BOCD) as a means of improving ESCR without the processability and stiffness debits. Through blending high melt index, high density components with low density, low melt index components to a target MI/ density, ESCR improvements of up to two orders of magnitude are evident over their single component counterparts.
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Brown, H. L. and Jones, D. H. 2016, May.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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