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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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Conference Proceedings

EVOH for Pharmaceutical Sustainable Forming Films
Edgard Chow, March 2023

Blister packs is one of the most important presentations in the pharmaceutical industry. As we all know, the brand owners and the global market are being pushed by the sustainability trends and regulations to look for alternatives towards recyclability. Typical structures of blister packs contain not friendly materials like PVC, PVDC OR PCTFE. This conference will present some test of structures using EVOH and COC creating a blister packaging with high barrier and excellent optical properties that also are design for mechanical recycling.

Ensuring the Safe Use of Recycled Polymer Resins Through the Development of Testing for Volatile Organic Compounds. Discussion on Methodology and Results
Kevin Guigley, Ph.D., March 2023

It is well known that melt processing post-consumer (PCR) or post-industrial (PIR) recycled resins can generate foul odors due to contamination and/or thermal degradation. Additional components, such as printing inks and adhesives in plastic packaging, may be viewed as contaminates in the recycled resin and can contribute to this problem. Some of these odors could be from volatile organic compounds, VOC’s, with known safety concerns. With a growing need in the flexible packaging industry to increase circularity through the use of PCR and PIR materials, there comes an increase in risk for health concerns and food safety. Amcor has developed methods using gas chromatography, GC, along with heated headspace sampling, HS, to chemically identify and measure the VOC released from PCR/PIR that have known safety concerns such as acrolein, methyl acrolein, and benzene. These methods help Amcor evaluate the quality of PCR/PIR sources to determine feasibility for certain applications, and aid in the design of next-generation recycle ready packaging films. This will be a discussion on the development of the testing methods along with results of VOC analysis.

Synthesis of Thermoresponsive Hydrogels for Atmospheric Water Vapor Harvesting
Pavani Cherukupally, Ph.D., March 2023

About 4 billion people around the world are suffering from water scarcity, which is expected to increase due to increasing global warming [1, 2]. One of the solutions to address the water scarcity challenge is to tap the 13,000 trillion of water present in the atmospheric air in the form of fog, droplets, or vapor [3]. Simple fog collection systems effectively harvest water without investing energy in highly humid environments [4], but they are ineffective in arid regions like Arizona, where the humidity is low. Alternatively, adsorbents designed to capture water vapor during colder nights and release it during the hotter day could provide a passive solution to harvest water vapor in the arid regions of the world [5,6]. Recently, porous polymeric hydrogels have been reported for water droplets harvesting from the air. The gels were fabricated with thermoresponsive polymers, such as polypyrrole chloride penetrated PNIPAM, that can switch to hydrophilic and hydrophobic structures at lower critical solution temperature (LCST) and upper critical solution temperature (UCST), respectively [7,8]. By leveraging their switchable wetting properties, the water droplets were captured during the night at higher humidity and lower temperature conditions and collected during the day at lower humidity and higher temperature conditions. However, the influence of LC/UCST on the hydrogel's chemical and morphological structures has not been investigated, as well as harvesting water vapor present in arid regions. In this work, we report the fabrication of thermoresponsive P(NIPAM-co-BzDMA) copolymeric hydrogel to collect water vapor from the air across all humidity conditions. The hydrogels were fabricated by tuning the temperatures and compositions to achieve large surface area-to-volume ratios, ordered porous structures, and excellent switch between the hydrophilic-hydrophobic wetting properties. The gels synthesized at LCST at BzDMA salt concentration of 15% could uptake 20% higher water than their counterparts. Experimental: The P(NIPAM-co-BzDMA) gels were synthesized by thermally initiated polymerization at LCST or UCST to determine the influence of their switchable hydrophilic-hydrophobic structures on the efficacy of crosslinking [9]. Then the PNIPAM was copolymerized with BzDMA salt at three concentrations of 10%, 15%, and 20% by weight. The synthesis was carried out for 4 hours under nitrogen and then freeze-dried for 12 hours in vacuum environments. The resulting porous gels were named based on their salt concentrations as P(NIPAM-co-10%BzDMA), P(NIPAM-co-15%BzDMA), and P(NIPAM-co-20%BzDMA). The surface functional groups of the hydrogels were determined using Fourier Transform Infrared Spectroscopy (FT-IR, Bruker, Germany). The morphological and crosslinking structure of the gels were evaluated using scanning electron microscopy (SEM, Hitachi Instrument, Japan). The thermoresponsive phase change behavior of the materials was verified using a Differential Scanning Calorimetry (DSC) at a heating rate of 2 C/min from 10 to 60C under a nitrogen environment (DSC, TA Instrument, USA). The switchable wetting properties of the gels were examined through water contact angles (WCA) measured at 20 and 40C. The water vapor adsorption-desorption isotherms were measured using an intelligent gravimetric analyzer (IGA, Hiden Isochema Ltd., UK). Results & Discussion: The successful synthesis of PNIPAM at LCST and UCST was confirmed from the FT-IR spectra. It showed two intense peaks at 1677 and 1563 1/cm, corresponding to C=O and N-H or C-N, respectively. The spectra also showed bimodal peaks at 1390 and 1379 1/cm from the isopropyl, peaks at 2987 and 2942 1/cm from methylene, and a broad peak at 3310 1/cm from N-H stretching [10]. Relative to LCST, the functional groups showed more intense peaks for PNIAM @UCST. It could be because the large number of oxygen radicals generated at higher temperatures could increase crosslinking of PNIPAM. The SEM images of the P(NIPAM-co-BzDMA) hydrogels showed interconnected microporous structures caused by freeze-drying [11]. Compared with PNIPAM@UCST, the PNIPAM@LCST had orderly distributed pores. The BET (Brunauer, Emmett, and Teller) surface area of the PNIPAM@UCST and PNIPAM@LCST were 2.91 mˆ2gˆ-1 and 2.67 mˆ2gˆ-1, respectively. At LCST, the slow copolymerization reaction rate and the homogeneous hydrophilic-hydrophilic structures of copolymers created orderly-distributed, uniform pores across the hydrogels. In contrast, at UCST, the fast copolymerization reaction rate and heterogeneous hydrophilic-hydrophobic networks of copolymers produced randomly-distributed, nonuniform pores. The BzDMA could react and maintain a stable morphological structure with both gels. The DSC thermograms confirmed that both PNIPAM and P(NIPAM-co-BzDMA) could change phase at approximately 32 C. Next, the WCAs measurements showed that all gels exhibit superhydrophilicity at 20C and hydrophobicity at 40 C, as intended. The adsorption-desorption isotherms of hydrogels showed an S shape curve suggesting water vapor can be harvested without losses. However, below LCST, due to superhydrophilicity of PNIPAM and P(NIPAM-co-BzDMA), the water molecules have a higher affinity to bind with the adsorbent, swell and cause a larger hysteresis loop and higher water uptake capacity. The water uptake capacity was found to be 20% highest for P(NIPAM-co-BzDMA) at 15% salt concentration than its counterparts. Conclusions: Our results suggest the influence of synthesis temperature-dependent chemical structures on the overall water vapor uptake capacities and collections was negligible. However, the gels synthesized below LCST and 15% salt concentrations slowed the copolymerization reaction rate, created uniform morphology, and delivered a higher water uptake capacity. Based on these process parameters and compositions, scalable hydrogel-based adsorbents can be designed for large-scale water vapor harvesting across all climate conditions, especially in highly-needed arid regions. References: 1. G. Meran, M. Siehlow, C. von Hirschhausen, The Economics of Water: Rules and Institutions. Springer Nature (2021). 2. M. M. Mekonnen, et al. Sci. Adv 2 (2), e1500323 (2016). 3. H. Kim, et al. Science 356 (6336), 430-434 (2017). 4. J. Ju, et al. Nat. Comm. 3 (1), 1-6 (2012). 5. N. Hanikel, et al. Nat Nanotechnol 15 (5), 348-355 (2020). 6. P.A. Kallenberger, et al. Comm. Chemistry 1(28), 1-6 (2018). 7. F. Zhao, et al. Adv. Mater. 31 (10), 1806446 (2019). 8. K. Matsumoto, et al. Nat. Comm. 9 (1) 1-7 (2018). 9. H. Yang, et al. Adv. Mater. 2013, 25 (8), 1150-1154. 10. Y. Dong, et al. Appl. Surf. Sci. 307, 7-12 (2014). 11. Z. Shen, et al. Soft Matter 8 (27), 7250-7257 (2012). 12. W. Xu, et al. ACS Cent Sci 6 (8), 1348-1354 (2020).

A Review on LCA Studies on Grocery Plastic Bags and Their Substitutes
Iván Darío López Gómez, Alejandro Serna Escobara, March 2023

Single-use bags have been banned or restricted around the world. Substitute alternatives have been explored, including biodegradable bags, reusable bags and the use of other materials such as paper or cotton. The Life Cycle Assessment (LCA) is the most widely accepted tool for carrying out comparative studies between alternatives. In this study, the literature on LCA of grocery bags was reviewed in search of common conclusions. In general, reusable plastic bags are identified as the alternative with the lowest environmental impact , obtaining on average a 73% reduction in the climate change index compared to the alternative with the highest impact in each analysis. Reuse and recycling have a lower environmental impact than composting, landfilling or incinerating. Open challenges are discussed, including the requirement for the development of a new index to quantify plastic leakage into the environment.

Design From Recycling: How to Design Robust Plastic Parts Maximizing Their Recycled Content
Giovanni Lucchetta, Ph.D., March 2023

With climate change worsening, people have become more conscious of their environmental impact. Companies are receiving growing pressure to use increasing content of post-consumer recycled (PCR) plastics in their products. However, PCR plastics differ from virgin materials in several mechanical, physical, and rheological properties, posing design and molding challenges for manufacturers. In this work, a polypropylene (PP) compound is produced and characterized using different contents of PCR PP to model its properties as a function of PCR content. A numerical approach is then proposed to determine the maximum content of PCR PP suitable for a given application. Furthermore, a robust design approach is proposed to identify engineering changes for both part and mold design that can make the part performance insensitive to lot-to-lot variations of the PCR properties.

Mechanical Properties of Bio-based Composite from Orange Peels
Yousef A. Mubarak, Deeb Abu Fara, March 2023

Orange peels have high cellulose content and they are available in good quantities. The present study aimed to a produce bioplastic composite based on orange peels. Orange peels were ground using a semi-automatic grinder before the pre-treatment step. The peels were immersed in a 15% sodium hydroxide NaOH solution for 4 hours at 60°C to remove the lignin, hemicelluloses, and other pectic substances. Then, they were neutralized with 1% acetic acid before being washed with distilled water and dried overnight at 60°C in a convective oven. Different natural additives, including starch, glycerol, agar-agar, and D- sorbitol, were added to the orange peels to develop the bioplastic material for optimized mechanical and plasticizing properties. To enhance the mechanical properties of the orange peel bioplastic, calcium carbonate was used in different weight percentages.The ultimate tensile strength of the orange peels bioplastic samples increased from 0.9 MP to 2.4 MPa with the addition of 8 wt% calcium carbonate. On the other hand, the fracture point decreased from 20% to almost 13% strain by the addition of calcium carbonate, the bioplastic become more brittle as the weight percentage of calcium carbonate increased. The bending tests showed that the maximum deflection achieved before fracture is equal to 12 mm and that the specimen can withstand forces up to 6.2 N. This indicates that the achieved biomaterial has a remarkable bending strength and can withstand up to 6.2 N before fracture, proving that it has a strong bending behavior. The deflection decreased by about 20% when 8 wt% of calcium carbonate existed in the matrix and the bending withstand force reduced to about 5.0 N. It is expected that applying a coating layer to the orange peels bioplastic end products makes them more attractive and expands their commercial applications.

Confinement and Complex Viscosity
Steacy Coombs, March 2023

Whereas much is known about the complex viscosity of polymeric liquids, far less is understood about the behaviour of this material function when macromolecules are confined. By confined, we mean that the gap along the velocity gradient is small enough to reorient the polymers. We examine classical analytical solutions [Park and Fuller, JNNFM, 18, 111 (1985)] for a confined rigid dumbbell suspension in small-amplitude oscillatory shear flow. We test these analytical solutions against the measured effects of confinement on both parts of the complex viscosity of a carbopol suspension and three polystyrene solutions. From these comparisons, we find that both parts of the complex viscosity decrease with confinement, and that macromolecular orientation explains this. We find the persistence length of macromolecular confinement, ?? , to be independent of both ?? ?? and?? ?? 0.

Effect of Shear of and Pressure on Structure for Binary Blends of Bisphenol — A Polycarbonate and Poly(methyl Methacryslate)
Masayuki Yamaguchi, March 2023

The effect of applied shear flow and pressure on the miscibility and structure for the binary blends of bisphenol-A polycarbonate (PC) and low-molecular-weight poly(methyl methacrylate) (PMMA) was studied using a conventional capillary rheometer. The lower critical solution temperatures (LCSTs) of PC/PMMA (70/30) and PC/PMMA (80/20) were found to be 260 and 270°C, respectively, without flow field under atmospheric pressure. During capillary extrusion at/below 250°C, however, shear induced demixing was detected. Moreover, pressure induced demixing was also detected at high pressure. Finally, surface segregation of PMMA fraction was observed without phase separation for PC/PMMA (90/10).

Experimental Characterization and Modelling of the Pressure Dependence of the Viscosity for Injection Molding Simulations
Steffen Verwaayen, March 2023

The pressure dependence of melt viscosity of thermoplastic materials is difficult to measure and is therefore often neglected, although it can have a major influence on the results of an injection molding simulation. Current viscosity models provide the ability to model this dependence. Therefore, the viscosity is measured in a high- pressure capillary rheometer and the pressure dependence of the viscosity is determined in an online rheometer for a polypropylene. The generated experimental data is used as input to fit the Carreau-WLF model. The accuracy of the models varies depending on the input data chosen. In particular, the pressure dependence of the viscosity could not be correctly represented while maintaining good viscosity representation. A correction of the neglected pressure during the high-pressure capillary rheometer measurement improved the modeling of the pressure dependence of the viscosity slightly.

Exploiting Structure-Process Property Relationships of Branched Polycarbonates for Industrial Applications
Manojkumar Chellamuthu, Ph.D., March 2023

Current electrification market needs materials with good balance of Flow, Flame Property and Mechanical Performance. In this talk, we will discuss the rheological features of three commercially available linear, branched and hyper-branched polycarbonates (PCs) using comprehensive investigations. Applications of rheological properties to enhance Z-strength in Large Format Additive Manufacturing (LFAM) will also be discussed. Additionally, high temperature extensional Rheometer (CaBER) was used to understand the evolution of microstructure at high temperatures. The experiments were performed at temperatures ranging from T = 250 to 370 °C to a maximum Hencky strain of ten. At lower end of the temperature range, no significant degradation of the linear and branched Polycarbonate (PC) was observed either in the shear or extensional measurements. Beyond, T > 300 °C branched PC showed a dramatic increase in extensional viscosity which helps in Flame performance (anti-drip) better than its linear counterpart.

Introducing a Differentiable, Shear-Thinning Viscosity Model
Paul Van Huffel, March 2023

A differentiable model for non-Newtonian, shear- thinning viscosity is presented as derived by integrating the log-log domain derivative function of the Carreau-Yasuda viscosity model. This work starts with the discovery of the log-log domain derivative function as this is the foundation for the statement of the new viscosity model. Potential uses for this work include development of explicit or hybrid flow solvers for polymer flows and possibly extending into the incorporation of effects based on the rate of change of the spherical (i.e. expansion/compression) and deviatoric parts of the rate-of-strain tensor, although this model specifically deals with the deviatoric part. A fitting experiment of rheometer data that was initially fit for each temperature curve as part of another work is used to demonstrate the flexibility of having a variable curve shape parameter as opposed to a fixed value, and a simulation of a conical section is used to compare the apparent wall shear rate in a converging channel versus the numerically obtained shear rate by a finite element analysis of the same conical channel.

Steady State and Dynamic Oscillatory Shear Properties of Carbon Black Filled Elastomers
Avraam Isayev, Ph.D., March 2023

A correlation between the steady shear viscosity and complex dynamic viscosity of carbon black (CB) filled rubbers was found by evaluating the Cox-Merz rule and an alternative approach originally proposed by Philippoff for dilute polymer solutions, but since applied to amorphous polymers and concentrated suspensions. This was done by measuring the rheological properties of 16 industrially important rubber mixes containing CB N660 at concentrations of 20 and 35 % by volume. A capillary rheometer at various shear rates and a dynamic oscillatory shear rheometer at small and large amplitude oscillatory shear (SAOS and LAOS) were used. The apparent viscosity, storage and loss moduli, complex dynamic viscosity and Fourier transform harmonics were measured. Generally, the shear stress, storage and loss moduli increased with increasing CB loading. Also, the ratio of 3rd and 5th stress harmonics to 1st harmonics increased with increasing strain amplitude and filler loading. Viscous Lissajou figures (shear stress versus shear rate) at a strain amplitude of 14% showed a nearly linear response for compounds containing CB at 20% by volume. All other shear stress responses demonstrated a strong nonlinearity. The stress waveforms at a strain amplitude of 140% for compounds containing 35% CB by volume displayed a backwards tilted shape expected for highly filled compounds. The stress waveforms at a strain amplitude of 1,000% tended toward a rectangular shape expected for pure polymer. Generally, the nonlinear response of the compounds appeared to be dominated by the filler at strain amplitudes of 14% and 140% and by the rubber matrix at a strain amplitude of 1,000%. The Cox-Merz rule was not applicable for any of the compounds with their complex dynamic viscosity being greater than the apparent viscosity. However, a modification of the approach proposed by Philippoff provided reasonable agreement between the apparent viscosity and complex dynamic viscosity.

Using Thermal and Rheological Techniques to Help Guide Recycled PET Extrusion Processing
Tianhong Chen, Ph.D., March 2023

Polyethylene terephthalate (PET) is one of the most commonly used plastics in our daily life. It is completely recyclable and is the most recycled plastic in the U.S and worldwide. However, recycled PET from different sources may have large variabilities, such as reduced molecular weight, broader molecular weight distribution, different crystallinity, and containing different impurity contents, all of which can affect their processing and application. This presentation will discuss of using thermal and rheological techniques to fingerprint the feedstock resins and help guide extrusion processing. Specifically, we will discuss using differential scanning calorimetry (DSC) to identify the type of impurities, monitor the effect of thermal history on the crystallinity and crystal melting. We will also discuss using rheological techniques to estimate the molecular architecture, measure melt stability, melt viscosity, and help optimize extrusion conditions.

Time, Temperature & Applied Rheology in Wire & Cable
Scott Wasserman, March 2023

Many years ago, Union Carbide Corporation (UCC) had established a well-equipped melt rheology lab designed to accomplish large-scale melt testing to simulate high shear conditions and small-scale dynamic and steady shear capabilities to both predict low deformation phenomena and delineate key features of molecular structure. UCC later initiated an aggressive metallocene catalyst development program to develop polyethylenes (PEs) with unique molecular structures. In an effort to fully characterize the key features of molecular structure that was manifested in the observed viscoelastic properties, we calculated the melt relaxation spectra for the new PEs and in comparing them to incumbent PEs, we found the new PEs to be differentiated. This led to a family of patent applications [1] to protect the technology, and a new parameter, called the “relaxation spectrum index” or “RSI” to quantify the breath of the relaxation time distribution reflecting the novel molecular structures. The RSI proved to be a useful parameter to use to not only delineate interesting features of molecular structure, but also to predict large-scale processing behavior, such as motor load and amperage in extrusion of layers and components for wire and cable applications [2]. This presentation will illustrate the power found in calculating and characterizing the relaxation spectrum with dynamic oscillatory shear experiments. As an illustration, a case study will be presented in which a new compound was to be developed for high-speed thin-walled chemical-foamed telecommunications wire insulation. Many key rheological phenomena needed to be simultaneously considered to design the next-generation product, and the RSI proved to be instrumental in allowing the necessary differentiation between inventive and comparative materials. This led to the development of a powerful set of patent claims [3] to protect the strategic space for UCC (now Dow). The power of this rheology-based approach to intellectual property is that the invention is not limited to a particular composition – instead, the patent claims would be a potential challenge to any composition that meets the critical rheological profile. References 1. G. N. Foster, T. Chen, S. H. Wasserman, D.C. Lee, S. J. Kurtz, L. H. Gross, R. H. Vogel, U.S. Patent 5,798,427 (1998). 2. Wasserman, SH & Adams, JL. “Rheology and Crystallization in Fiber Optic Cable Jacket and Conduit Extrusion,” ANTEC 1997, Toronto, CA April 27-May 2, 1997. 3. S. Maki, G. D. Brown, S. H. Wasserman, D. J. Frankowski, V. Y. He, U.S. Patent 6,455,602 (2002).

3-D Printing of Thermoplastic Polyurethane Foams using Thermally Expandable Microspheres
Nikith Lalwani, Karun Kalia, Amir Ameli, March 2023

Thermoplastic polyurethane (TPU) foams have a wide range of applications due to their high elasticity, good flexibility, low density, and high resistance to impact forces. They are used as cushioning for a variety of consumer and commercial products, including furniture, automotive interiors, helmets, and packaging. 3D printing of TPU foams would enable increased product design freedom and graded structures for novel and enhanced applications. To this end, unexpanded TPU filaments loaded with 0.0%, 7.5%, and 15.0wt.% thermally expandable microspheres (TEM) were prepared using a single screw extrusion system. TEM was incorporated using a masterbatch with 50wt.% ethylene-vinyl acetate carrier. The extrusion process parameters were set to achieve the lowest possible melt temperatures to prevent the foaming during filament fabrication. Foam samples were then in-situ printed using fused filament fabrication (FFF) process. 3-D printing parameters such as flow rate, print speed, and nozzle temperature were varied to achieve a wide range of foam density. Scanning electron microscopy and quasi-static compression tests were performed to characterize the cellular morphology and mechanical performance of the printed samples. Foams with good printability and dimensional accuracy were successfully achieved with densities as low as 0.15 g/cm3. The ability to 3-D print TPU foams with different densities provides higher design flexibility and allows to create more complex and optimized structures for a number of applications.

Conducting a Plastic Failure Analysis
Jeffrey A. Jansen, March 2023

Agenda

  • Defining Failure
  • Plastic Part Performance Factors
  • Understanding Failure Rate in Plastic Components
  • Plastic Failure Mechanisms
  • Failure Analysis Methodology
  • Failure Analysis Testing
  • Case Illustrations

Study On Machine Identification And Its Effect On The Rsm Optimization In Injection Molding
Rui-Ting Xu, Tsung-Han Wang, Chao-Tsai (CT) Huang, Po-Hsuan Chen, Wen-Ren Jong, Shia-Chung Chen, David Hsu, Rong-Yeu Chang, June 2022
Preliminary Investigation Of Oxygen Pressurized Chambers For Accelerated UV Weathering
Henry K. Hardcastle III, June 2022

This paper presents results of a preliminary proof-of-concept investigation into the effect of pressurized oxygen on UV photodegradation rates of a polystyrene standard reference material. Exposures under UVA and UVB revealed significant and important acceleration effects using pressurized oxygen compared with ambient air.

Novel Nanocellulose Based Supports For PHBV Composites - Synthesis And Properties
Kavan Sheth, Ting Zheng, James Sternberg, Craig Clemons, Srikanth Pilla, June 2022

Novel nano-cellulose based nano-structures modified with hyper-branched polymers were prepared by using isocyanate linking chemistry. The chemistry was investigated using FTIR spectroscopy. The composites were homogenized utilizing solvent casting followed by injection molding of the samples. The thermal properties of the prepared samples were investigated using DSC and TGA.

Melting Performance Analysis Of A Single-Screw Extruder With A NSB Screw
Xiaofei Sun, Ryan A. Pratt, Mark A. Spalding, Jeffery A. Myers, Robert A. Barr, Aaron F. Spalding, June 2022

A recent design of a new screw referred to as the No Solid Bed (NSB) screw was introduced and the initial operation was presented [1]. This new screw has channels in the transition section that do not allow a compacted solid bed to form. The data presented here compliments the data that was previously published.










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