SPE Library

3 Challenges of Testing Plastics

Sammi Sadler & Stephanie Williams, September 2023

The world of plastics is constantly evolving, with new applications such as high-performance polymers, additive manufacturing, and bioplastics continually emerging to transform the field. Common to all applications - old and new - is the importance of mechanical testing that ensures manufacturers are producing quality products. In this webinar we'll be discussing the specific challenges of testing plastics, the importance of repeatable and reliable mechanical testing results, and what you can do to improve your results. Topics

• Overview of recent changes in key standards
• Factors that influence test results – solutions and troubleshooting tips
• How to increase laboratory efficiency and throughput to improve test times

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.

Effect Of Talc And Carbodiimide On The Hydrolytic Resistance Of A Poly(L-Lactic Acid) Compound

Nishant Singh, Celina Alvarado, Carlos A. Diaz, Baxter Lansing, Christopher L. Lewis, June 2022

In this work we examine the influence of talc and a polymeric carbodiimide on the hydrolytic degradation resistance of a commercially available Poly(L-Lactic acid) PLLA. Here, polymer blends containing 0-4wt% talc, a crystal nucleating agent and 0-1 wt% of a polymeric carbodiimide (CDI), an anti-hydrolysis agent, were melt blended and compression molded into plaques. Samples were then submerged in a phosphate buffer solution (PBS) at 50°C for up to 60 days. Results indicate that the presence of talc as the sole ingredient in the formulation increases the crystallization rate and this translates to an increase in the degree of crystallinity of compression molded plaques and a modest improvement in hydrolytic degradation resistance as compared to unfilled PLLA. The presence of CDI retards PLLA crystallization. In spite of this, compounds containing CDI exhibited much greater hydrolytic degradation resistance than PLA with the effect being more pronounced with increasing CDI concentration. Under DSC conditions, the addition of 1wt% talc to CDI containing compounds improved the non-isothermal crystallization rate at 5°C/min but this effect diminished as cooling rate increased and this explains the low crystallinity of compression molded samples. However, compounds containing both talc and CDI showed an improved hydrolysis resistance as compared to compounds containing only CDI implying that talc's role in reducing the rate of hydrolysis is caused by the hydrophobic characteristic of the material. It is envisioned that this work will help pave the way for the usage of PLA in durable applications where long-term resistance to humidity is anticipated.

Effect Of Plasma Treatment On Degradation Of Biodegradable Mulch Film

Swapnil Bhattacharya, Harshal J. Kansara, Celina E. Alvarado, Carlos A. Diaz, Jeffrey Lodge, Christopher L. Lewis, June 2022

Mulch films modify soil conditions thus improving crop output, hence are widely used across the world. Traditional PE (polyethylene) films do not degrade and must be disposed of afterwards. Biodegradable mulch films (BMFs) provide a much better alternative and are meant to be tilled with the soil after harvest. But most BMFs degrade slowly and accumulate in soil, harming the soil productivity. In this investigation we evaluate the effect of gliding arc plasma treatment on the behavior of a commercially available biodegradable mulch film based on polybutylene adipate co-terephthalate (PBAT) and polylactic acid (PLA). Following plasma treatment an initial increase in the hydrophilicity of the films is observed and this is attributed to an increase in oxygen containing species on the surface. Moreover, hydrophobic recovery is slow as indicated by contact angle measurements taken over a 30-day time. Thermal analysis results indicate no significant difference indicating that treatment is confined primarily to the surface. A treated film showed enhanced disintegration as compared to an untreated film following 65 days of composting in an aerated static pile compost. These results indicate that plasma treatment may aid the biodegradation of plastic mulch films and therefore eliminate their accumulation in soil.

From Petroleum To Biobased Crude: A Thermoplastic Polyurethane From Lignin-Oil Without Isocyanates

James Sternberg, Srikanth Pilla, David G. Brandner, Reagan J. Dreiling, Arik Ringsby, Jacob S. Kruger, Gregg T. Beckham, June 2022

The movement to transfer from petroleum-based products and materials to renewables does not necessarily have to bypass the use of oil. A new type of “black-gold” is readily abundant from the earth’s most abundant source of aromatic carbon: lignin. While fractionation of petroleum yields fuels and chemicals for a diverse set of industries, lignin fractionation using targeted catalysts has demonstrated the ability to generate monomers and oligomers rich in functional groups for polymer synthesis. This study explores the use of lignin-oil, generated from reductive catalytic fractionation of popular wood, to a hydroxyl-rich mixture of aromatics that is used to synthesize a thermoplastic non-isocyanate polyurethane. The lignin-oil is first converted to a cyclocarbonated derivative using a benign synthetic sequence and further polymerized with a diamine to yield the non-isocyanate TPU. While more work is underway to optimize the reaction conditions and meet typical mechanical properties of commercial materials, initial analysis shows thermoplastic behavior and flexible properties consistent with traditional thermoplastic polyurethanes.

Compounding and Characterization of Polylactic Acid-Sawdust Deep Eutectic Solvent Extracted Lignin

Saurabh Pawale | Karun Kalia | Dylan Cronin | Xiao Zhang | Amir Ameli, August 2021

There is an ever increasing need for sustainable and biobased materials. Plant-based feedstock such as cellulose and lignin can potentially become competitive resources as alternatives to fossil-based materials. Lignin as an inexpensive feedstock has been examined toward preparing polymer composites. It however faces some challenges including its detrimental impact on the mechanical and thermal properties of the resultant composites. This work reports the fabrication and characterization of polylactic acid/lignin composites with the incorporation of a new type of lignin, called deep eutectic solvent (DES) extracted lignin. White fir sawdust was used as feedstock to extract DES lignin. For comparison, commercial alkali lignin (CAL) was also used as a benchmark. PLA/lignin composites containing 0-15 wt.% lignin were fabricated using twin screw extrusion process followed by compression molding. Composites characterization were conducted using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and tensile testing. The results revealed that the mechanical and thermal behaviors of DES lignin composites significantly outperformed their CAL counterparts. For composites with 15 wt.% DES, the tensile strength, Young’s modulus, and elongation at break dropped by ~33, 7 and 45%, respectively, compared to those of neat PLA. However, the composites with 15 wt.% CAL showed 90, 45 and 86% drop in the strength, modulus, and elongation, respectively. The initial thermal degradation temperature of PLA dropped by ~ 8-27 °C with the incorporation of 5-15 wt.% DES lignin. On the other hand, the introduction of CAL to PLA lowered the degradation temperature by ~89-124 °C. DSC also showed a drop in the glass transition temperature (Tg) and melt temperature (Tm) for both the composites but the drop was less significant for DES lignin composites. The good performance of PLA/DES lignin composites may be associated with the DES lignin’s high purity, low heterogeneity, low molecular weight, fine particle size as well as its homogenous dispersion and compatibility with PLA matrix.

Self-reinforced Polylactide Composites Manufactured by Melt Spunbond Technology

Amirjalal Jalali | Anthony Tuccitto | Sandra Romero-Diez | Patrick C. Lee | Chul B. Park, May 2021

A series of stereocomplex polylactide (SC-PLA) blends (PLLA 95 wt%/PDLA 5 wt%) were prepared by spunbond technology. For this, the compounds of linear PLLA, and low and high molecular weight as well as branched PDLAs were spun at two different temperatures. They were spun at 190 °C, which was below the melting temperature of the stereocomplex crystals. And, they were melt-spun at 230 °C, which was above the melting temperature of the stereocomplex crystals. Morphological observation of the etched samples showed that the samples spun at 190 °C demonstrated tiny spherical crystals exhibiting diameters in the range of 100–200 nm; however, the samples spun at 230 °C showed thin fibers in the size range of 60–70 nm. The obtained results were supported by shear and elongational rheological measurements. Moreover, crystallization kinetics of the samples was also enhanced after spinning and was largely dependent on the spinning temperature. Tensile modulus and strength of the spun samples was also significantly improved. The spun samples also presented a considerable decrease in boiling water and hot air shrinkage.

Compostable Adhesive Formulations for Extrusion Lamination

Sayli Bote | Alexander Ermlich | Shilpa Manjure, May 2021

In this work, two compostable adhesive formulations, i.e., Resin A – MPP (Major PLA phase) and Resin B – MINPP (Minor PLA phase), were developed and evaluated for their performance as an adhesive in the extrusion lamination process. The densities of both the resins were in the range of 1.26-1.32 g/cc. The MFI values of Resin A and Resin B were 5 and 3 (g/10 min at 190ºC/ 2.16 kg), respectively. The complex viscosity of Resin A was lower than the complex viscosity of Resin B. The percent neck-in of Resin A at 235ºC was almost 4 times as that of Resin B at same conditions. The percent neck-in increased with increasing the temperature and distance from the die. Multilayer laminates were made using cellophane and metalized cavitated PLA as substrates, and Resin A or Resin B as adhesive. The adhesive strength of the Resin B to the cellophane was 20 g/cm, which was 10 times higher than the adhesive strength of Resin A (2 g/cm) to the cellophane. Also, the adhesive strength over the period of two weeks did not decrease significantly.

Prediction of Enzymatic Degradation of Poly-g-Caprolactone with Esterase Using a Reaction Model

Iftekhar Ahmad | Mohammad Abubakar Kha, May 2021

An enzymatic degradation mechanism of Poly- ε-Caprolactone (PCL) is discussed in this paper. A ping-pong bi-bi reaction mechanism with esterase is chosen to obtain the model equations. The reaction rate constants were either estimated or fitted in the model. The model is then utilized to predict concentration vs time plots for PCL and a degradation product, hydroxycaproic acid. The reaction between the enzyme and polymer is found to be rate limiting because of the limited polymer surface available for reaction. The predictions of the model are compared to experimental results reported in literature.

Preparation and Characterization of Polylactic Acid-Sawdust Deep Eutectic Solvent Extracted Lignin

Saurabh Pawalea | Karun Kaliaa | Dylan Croninb | Xiao Zhangb | Amir Ameli, May 2021

There is an ever increasing need for sustainable and biobased materials. Plant-based feedstock such as cellulose and lignin can potentially become competitive resources as alternatives to fossil-based materials. Lignin as an inexpensive feedstock has been examined toward preparing polymer composites. It however faces some challenges including its detrimental impact on the mechanical and thermal properties of the resultant composites. This work reports the fabrication and characterization of polylactic acid/lignin composites with the incorporation of a new type of lignin, called deep eutectic solvent (DES) extracted lignin. White fir sawdust was used as feedstock to extract DES lignin. For comparison, commercial alkali lignin (CAL) was also used as a benchmark. PLA/lignin composites containing 0-15 wt.% lignin were fabricated using twin screw extrusion process followed by compression molding. Composites characterization were conducted using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and tensile testing. The results revealed that the mechanical and thermal behaviors of DES lignin composites significantly outperformed their CAL counterparts. For composites with 15 wt.% DES, the tensile strength, Young’s modulus, and elongation at break dropped by ~33, 7 and 45%, respectively, compared to those of neat PLA. However, the composites with 15 wt.% CAL showed 90, 45 and 86% drop in the strength, modulus, and elongation, respectively. The initial thermal degradation temperature of PLA dropped by ~ 8-27 °C with the incorporation of 5-15 wt.% DES lignin. On the other hand, the introduction of CAL to PLA lowered the degradation temperature by ~89-124 °C. DSC also showed a drop in the glass transition temperature (Tg) and melt temperature (Tm) for both the composites but the drop was less significant for DES lignin composites. The good performance of PLA/DES lignin composites may be associated with the DES lignin’s high purity, low heterogeneity, low molecular weight, fine particle size as well as its homogenous dispersion and compatibility with PLA matrix.

3D Printing Sustainable Biocomposites From Recycled PLA and Micro-Crystalline Cellulose

Akhilesh K. Pal | Erick O. Cisneros-López | Arturo U-Rodriguez | Feng Wu | Manjusri Misra | Deborah F. Mielewski | Alper Kiziltas | Amar K. Mohanty, April 2021

The motivation for this work was to increase the economic life of recycled poly(lactic acid) (rPLA) (30 wt%) by utilizing it with virgin PLA (70 wt%) in the presence of a fiber-based reinforcing filler, micro-crystalline cellulose (MCC) and an epoxy-based chain extender. A conventional melt extrusion technique was used to fabricate the strands with and without MCC and chain extender in the PLA/rPLA blend matrix. It was observed that the complex viscosity of rPLA was improved significantly after the addition of the chain extender, which resolved the issue related to excessive polymer flow during processing and hence made it possible for use in fused deposition modeling (FDM)-based 3D printing. The addition of the chain extender improved the impact strength of 3D the printed PLA/rPLA specimens. The voids in the 3D printed material contributed to the reduced weight of the developed sustainable composites. The modulus and tensile strength of the 3D printed sustainable biocomposites were improved significantly, and impact strength increased by ~10% by reinforcing the blended matrix with 5% of MCC.

Antioxidant Activity Effect of Isosorbide into Flexible Polyurethane Foams

Gwangseok Song, May 2020

Isosorbide alkylene oxide (ISB-AO) was obtained by reacted with isosorbide and alkylene oxide, a non-toxic bio-based bicyclic diol composed of two fused defurans to increase the reactivity of isosorbide. A flexible polyurethane foam was prepared using isosorbide alkylene oxide based isocyanate prepolymer (IAISO) consisting of a reaction of isosorbide alkylene oxide and isocyanate. FPUFs containing various types of IAISO have been successfully manufactured without significant degradation of the appearance and physical properties of the final foam. IAISO based FPUF also showed better antioxidant activity by preventing discoloration. Thus, IAISO using bio-based diols with improved reactivity can be valuable raw materials (or additives) born from environmentally friendly FPUFs without seriously compromising the physical properties of these FPUFs.

Degradable Plastics/Wood Hybrids For Sustainable Packaging Solutions

Simon Wurzbacher, May 2020

The costs for degradable plastics are in comparison to bulk plastics still high. To increase the market share of degradable-plastics-based products the reduction of the plastic used itself could be suitable option. To keep the degradable properties of the product suitable materials for a hybrid are wood or woodbased products like carton. In this paper, the combination of wood and degradable plastics to a hybrid material by overmolding was investigated. In this feasibility study the effects of injection molding on wood as an insert and the bonding strength between the two materials was analyzed.

Degradation Behavior of Aliphatic and Aromatic Biomass-based Copolyesters for Agriculture

Margaret Sobkowicz, May 2020

This work concerns the synthesis, characterization and evaluation of enzymatic degradation kinetics in three biobased polymers: poly(hexamethylene succinate), poly(hexamethylene 2,5-furan dicarboxylate) and a copolymer containing hexamethylene succinate (HS) and hexamethylene 2,5-furan dicarboxylate (HF) units. All three comonomers are available from renewable resources, and their use in agricultural films and coatings would reduce the incidence of microplastics in soils, and could also provide functionality in controlled release applications. We find that copolymerization of the aliphatic and aromatic monomers reduces the crystallinity in the polymer, thus increasing the degradation rate.

Vibration Welding of Agave Fiber Biocomposites

Curtis Covelli, May 2020

In this study, the welding of several formulations of injection molded agave-fiber filled biocomposites were studied. A 240Hz vibrational welder was used and weld pressure, amplitude, and weld time were varied to determine their effects on lap shear weld strength. Strength testing was performed with a universal testing machine. The morphology of the weld zones was also analyzed to gain insight into the mechanics of the welding.

Pushing the Limits to the Next Level: A New Mold Steel for Demanding Plastics and Biocomposites Designed for the Best Polishability

Magnus Brannbacka, May 2020

The increasing use of advanced engineeringplastic compoundsand biocomposites causes problems in the mold thatcan bederivedfrom a combination of wear and corrosion. The degradation of the tool steel resultsin increased maintenance, downtime and in worst case premature breakage of the mold.Manufacturing of optical devices, such as lenses, demands an extremely goodsurface finishof the mold[1]. In addition, it should be reached as fast as possible to reduce lead times.Uddeholm Tyrax® ESR isa newpremium martensitic tool steel from Uddeholm,developed to cope with these problems by combining corrosion resistance with high hardness,very goodwear resistanceand excellent polishabilitywithout compromising on ductility.The recommended hardness of Uddeholm Tyrax® ESR is in the range of 55-58 HRC.

Thermoplastic Elastomer Blend Exhibiting Combined Shape Memory and Self-Healing Functionality

Christopher Lewis, May 2020

Here we report on a polymer blend consisting of a soft-thermoplastic polyurethane (TPU) elastomer and a low melting temperature thermoplastic healing agent (Polycaprolactone, PCL) capable of repairing highly deformed cracks without the need for an external load. In this study, a blend containing 30wt% PCL (30PCL) was shown to exhibit two well-separated melting transitions thus enabling shape memory behavior. Moreover, upon heating to above PCL’s melting temperature the flow of PCL into an undeformed crack was shown to fill the crack void thus promoting self-repair. A combined healing mechanism relying on both shape memory and self-healing action was demonstrated. Through the simple action of mild heating (90C/30 minutes), fracture surfaces are brought into intimate contact through the action of shape memory recovery and subsequently healed. Healing efficiency was evaluated by comparing the tensile force restoration after healing of a highly deformed, notched sample to its behavior prior to notching. Here it was shown that the polymer blend exhibited full restoration of its originally mechanical integrity whereas the mechanical performance of pure TPU was only minimally restored (about 5%). This blend is based on thermoplastic ingredients and thus able to be converted using conventional melt processing. Applications of such blends can be extended to products prone to damage such as liner materials, protective coatings, sporting goods and shoe soles.

Upcycling Ocean Bound PET Waste Into Durable Materials

Peter Vollenberg, May 2020

Dealing with plastics waste is a major issue confronted by the society. Single use items from water bottles to plastic packaging are major contributors to the generation of plastics waste globally. Innovative upcycling technology can transform a plastic with limited applications and a brief useful life into a different, more-durable resin with expanded potential uses and an extended lifetime. In this way, upcycling can help strengthen the circular economy and can help reduce the impact of single-use plastic applications on the environment. Using propritary de-polymerization of recycled polyester, SABIC has introduced a more sustainable polyester products family containing up to 60% recycled materials. This new PBT and its compounds have similar purity and properties as virgin resin. Hence they are drop in for many virgin PBT or compounded products. Chemistry, properties, and application for these sustainable polyester materials will be discussed. In particular, the application of ocean bound based resin in Dell computer fan housing will be highlighted.

Trends in Bio-renewable Thermoplastics Elastomers

Krishna Venkataswamy, October 2010

Thermoplastic elastomers (TPEs) have been traditionally compounded and manufactured from raw materials based on fossil fuels. Current trends in marketplace abounds sustainability programs. TPEs are no exception to this trend. In a recent editorial, the authors stated “Through research and application, sustainability can evolve from a catchphrase to a societal one”. More than two decades ago the Brundtland Commission (formerly the World Commission on Environment and Development, WCED), deliberated sustainable development issue and gave a definition of sustainability: “Sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs.

Current Trends

Martin Vines, Ph.D., October 2007

Graphene is the thinnest known material and has the highest intrinsic strength of any material ever measured. We are posting an article to describe some of the interesting research on graphene and graphene-based polymer nanocomposites (GPNC) that is occuring. This article reviews how graphene is made, explain how single sheets can be dispersed in a polymer matrix to give plastics with interesting properties and where these works are being carried out.