Lignin is the most abundant natural source of aromatics but remains underutilized. Elemental sulfur is a plentiful by-product of fossil fuel refining. Herein we report a strategy for preparing a durable composite by the one-pot reaction of elemental sulfur and lignin oil comprising lower molecular weight lignin derivatives. A lignin oil-sulfur composite (
Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
-
Abstract LOS 90 ) was prepared by reacting 10 wt. % lignin oil with 90 wt. % elemental sulfur. The composite could be remelted and reshaped over several cycles without loss of properties. Results from the study showed thatLOS 90 has properties competitive with or exceeding values for commercial ordinary Portland cement and brick formulations. For example,LOS 90 displayed impressive compressive strength (22.1 MPa) and flexural strength (5.7 MPa).LOS 90 is prepared entirely from waste materials with 98.5% atom economy of composite synthesis, a lowE factor of 0.057, and lignin char as the only waste product of the process for its preparation. These results suggest the potential applications of lignin and waste sulfur in the continuous efforts to develop more recyclable and sustainable materials. -
Abstract Lignocellulosic biomass remains underutilized despite its annual production in gigaton quantities. Sulfur is another vastly underutilized waste product of fossil fuel refining. New mechanistic insight into the reactions of sulfur unveiled since 2020 suggest a rich and hitherto unexplored chemistry between biomass‐derived olefins and elemental sulfur. In this study, four biomass‐derived olefins (eugenol (
1 ), 4‐allyl‐2,6‐dimethoxyphenol (2 ),o ‐eugenol (3 ), and 2‐allyl‐6‐methylphenol(4) ) were reacted with elemental sulfur to elucidate the S−C bond‐forming and other reactivity of these compounds. Each of the compounds was reacted with elemental sulfur in three sulfur : organic reactant ratios (2 : 1, 4 : 1 and 9 : 1) and at two temperatures (180 °C or 230 °C). Product mixtures were characterized using1H NMR spectrometry and GC‐MS analysis. Products resulting from a range of mechanisms were unveiled, including inverse vulcanization, S−Callylic/benzylicbond formation, S−Carylbond formation, intramolecular cyclization, C−C σ‐bond scission, and C−O σ‐bond scission. It is anticipated that the insights from this study will support further synergy between the critical sustainability goals of biomass and sulfur utilization. -
Abstract Poly(methyl methacrylate) (PMMA) is an important commodity polymer having a wide range of applications. Currently, only about 10% of PMMA is recycled. Herein, a simple two‐stage process for the chemical upcycling of PMMA is discussed. In this method PMMA is modified by transesterification with a bio‐derived, olefin‐bearing terpenoid, geraniol. In the second stage, olefin‐derivatized PMMA is reacted with sulfur to form a network composite by an inverse vulcanization mechanism. Inverse vulcanization of PGMA with elemental sulfur (90 wt.%) yielded the durable composite
PGMA‐S . This composite was characterized by NMR spectrometry, IR spectroscopy, elemental analysis, thermogravimetric analysis, and differential scanning calorimetry. Composite water uptake, compressional strength analysis, flexural strength analysis, tensile strength analysis, and thermal recyclability are presented with comparison to current commercial structural materials.PGMA‐S exhibits a similar compressive strength (17.5 MPa) to that of Portland cement.PGMA‐S demonstrates an impressive flexural strength of 4.76 MPa which exceeds the flexural strength (>3 MPa) of many commercial ordinary Portland cements. This study provides a way to upcycle waste PMMA through combination with a naturally‐occurring olefin and industrial waste sulfur to yield composites having mechanical properties competitive with ecologically detrimental legacy building materials. -
Abstract Environmental damage caused by waste plastics and downstream chemical breakdown products is a modern crisis. Endocrine‐disrupting bisphenol A (BPA), found in breakdown products of poly(bisphenol A carbonate) (PC), is an especially pernicious example that interferes with the reproduction and development of a wide range of organisms, including humans. Herein we report a single‐stage thiocracking method to chemically upcycle polycarbonate using elemental sulfur, a waste product of fossil fuel refining. Importantly, this method disintegrates bisphenol A units into monoaryls, thus eliminating endocrine‐disrupting BPA from the material and from any potential downstream waste. Thiocracking of PC (10 wt%) with elemental sulfur (90 wt%) at 320 °C yields the highly crosslinked network
SPC 90 . The composition, thermal, morphological, and mechanical properties ofSPC 90 were characterized by FT‐IR spectroscopy, TGA, DSC, elemental analysis, SEM/EDX, compressive strength tests, and flexural strength tests. The compositeSPC 90 (compressive strength = 12.8 MPa, flexural strength = 4.33 MPa) showed mechanical strengths exceeding those of commercial bricks and competitive with those of mineral cements. The approach discussed herein represents a method to chemically upcycle polycarbonate while deconstructing BPA units, and valorizing waste sulfur to yield structurally viable building materials that could replace less‐green legacy materials. -
Abstract A three‐stage route to chemically upcycle post‐consumer poly(ethylene terephthalate) (PET) to produce high compressive strength composites is reported. This procedure involves initial glycolysis with diethylene glycol to produce a mixture (GPET) comprising oligomers of 2–7 terephthalate units followed by trans/esterification of GPET with fatty acid chains supplied by brown grease, an agricultural by‐product of animal fat of relatively low nutritional or fuel value. This process yields PGB comprising a mixture of mono‐terephthalate ester derivatives. The olefin units provided by unsaturated fatty acid chains in brown grease were crosslinked by an inverse vulcanization reaction with elemental sulfur to give composites GBS
x (x = wt% S, varied from 80%–90%). The compressive strengths of GBS80(27.5 ± 2.6 MPa) and GBS90(19.2 ± 0.8 MPa) exceed the compressive strength required of ordinary Portland cement (17 MPa) for its use in residential building foundations. The current route represents a way to repurpose waste plastic, energy sector by‐product sulfur, and agricultural by‐product brown grease to give high strength composites with mechanical properties suggesting their possible use to replace less sustainably sourced legacy structural materials. -
Abstract Rancid animal fats unsuitable for human or animal food production represent low‐value and abundant, yet underexploited organic chemical precursors. The current work describes a strategy to synthesize high sulfur‐content materials (HSMs) that directly utilizes a blend of partially hydrolyzed chicken fat and plant oils as the organic comonomers, following up on analogous reactions using brown grease in place of chicken fat. The reaction of sulfur and chicken fat with either canola or sunflower oil yielded crosslinked polymer composites CFSxor GFSx, respectively (
x = wt% sulfur, varied from 85%–90%). The composites exhibited compressive strengths of 24.7–31.7 MPa, and flexural strengths of 4.1–5.7 MPa, exceeding the value of established construction materials like ordinary Portland cement (compressive strength ≥17 MPa required for residential building, flexural strength 2–5 MPa). The composites also exhibited thermal stability up to 215–224 °C. The simple single‐step protocol described herein represents a way to upcycle an affordable and previously unexploited animal fat resource to form structural composites via the atom economical inverse vulcanization mechanism. -
Abstract Environmental contamination by plastic waste is a growing threat to the environment and human health. Unfortunately, most post‐consumer plastics are still disposed of in landfills, even plastics that could be easily recycled via simple chemical processes. This disconnect between technology and implementation is partly due to the economic barrier posed by multi‐step processes that convert plastic waste into commodity goods. There is an urgent need for green methods to convert plastic waste directly into marketable commodities via simple processes. Herein we report a simple, single‐stage process to chemically recycle poly(ethylene terephthalate) (PET) to yield composites having thermal and mechanical properties that are competitive with commercial structural materials like Portland cement. In this protocol, a mixture of PET and geraniol are heated with elemental sulfur. In this process, transesterification between geraniol and PET with concomitant thiocracking of the PET backbone leads to the formation of a highly‐crosslinked sulfur–PET–geraniol (SPG) network composite. The composite exhibited compressive strength (23.1 MPa) greater than that required for Portland cement to be used in building foundations. This new, single‐stage chemical recycling strategy thus employs a bio‐olefin and waste sulfur to convert PET waste into a durable composite that could serve as a sustainable alternative to traditional cements.
-
Abstract Low cost and high durability have made Portland cement the most widely‐used building material, but benefits are offset by environmental harm of cement production contributing 8–10% of total anthropogenic CO2gas emissions. High sulfur‐content materials (HSMs) are an alternative that can perform the binding roles as cements with a smaller carbon footprint, and possibly superior chemical, physical, and mechanical properties. Inverse vulcanization of 90 wt% sulfur with 10 wt% canola oil or sunflower oil to yield CanS or SunS, respectively. Notably, these HSMs prepared at temperatures ≤180 °C compared to >1200 °C hours for Portland cement CanS was combined with 5 wt% fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBFS), or metakaolin (MK) to give composites CanS‐FA, CanS‐SF, CanS‐GGBFS, and CanS‐MK, respectively. The analogous protocol with SunS likewise yielded SunS‐FA, SunS‐SF, SunS‐GGBFS, and SunS‐MK. Each of these HSMs exhibit high compressive mechanical strength, low water uptake values, and exceptional resistance to acid‐induced corrosion. All of the composites also exhibit superior compressive strength retention after exposure to acidic solutions, conditions under which Portland cement undergoes dissolution. The polymer cement‐pozzolan composites reported herein may thus serve as greener alternatives to traditional Portland cement in some applications.
-
The unique properties and sustainability advantages of sulfur polymer cement have led to efforts to use them as alternatives to traditional Portland cement. The current study explores the impact of environmental stresses on the strength development of polymer composite SunBG90, a material composed of animal and plant fats/oils vulcanized with 90 wt. % sulfur. The environmental stresses investigated include low temperature (−25 °C), high temperature (40 °C), and submersion in water, hexanes, or aqueous solutions containing strong electrolyte, strong acid, or strong base. Samples were analyzed for the extent to which exposure to these stresses influenced the thermo-morphological properties and the compressional strength of the materials compared to identical materials allowed to develop strength at room temperature. Differential scanning calorimetry (DSC) analysis revealed distinct thermos-morphological transitions in stressed samples and the notable formation of metastable γ-sulfur in hexane-exposed specimens. Powder X-ray diffraction confirmed that the crystalline domains identified by DSC were primarily γ-sulfur, with ~5% contribution of γ-sulfur in hexane-exposed samples. Compressive strength testing revealed high strength retention other than aging at elevated temperatures, which led to ~50% loss of strength. These findings reveal influences on the strength development of SunBG90, lending important insight into possible use as an alternative to OPC.
Free, publicly-accessible full text available June 1, 2025