The Experts below are selected from a list of 1227 Experts worldwide ranked by ideXlab platform
Jianbing Zeng - One of the best experts on this subject based on the ideXlab platform.
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biobased super hydrophobic coating on cotton fabric fabricated by spray coating for efficient oil water separation
Polymer Testing, 2018Co-Authors: Quanyong Cheng, Jianbing Zeng, Meichen Liu, Jiang ZhuAbstract:Abstract Super-hydrophobic materials for oil/water separation are usually prepared from non-renewable feedstocks, which does not coincide with the sense of sustainable development. Herein, we report a sustainable super-hydrophobic material fabricated via a simple spray-coating method from biobased feedstocks including epoxidized soybean oil, Sebacic Acid, stearic Acid, zinc oxide and cotton fabric. Rough surface structure was successfully constructed by spraying epoxidized soybean oil (ESO) with Sebacic Acid (SA) and nano-ZnO. After modification with stearic Acid (STA), the surface became super-hydrophobic with a water contact angle (WCA) of 155°. The super-hydrophobic fabric shows excellent stability without losing super-hydrophobicity after immersion in water and oil for several days. The super-hydrophobic fabric can selectively separate water mixtures with various oily liquids with separation efficiency higher than 97.5%. With high separation efficiency and excellent stability, the biobased super-hydrophobic fabric can be used as a sustainable and eco-friendly oil/water separation material.
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relating chemical structure to toughness via morphology control in fully sustainable Sebacic Acid cured epoxidized soybean oil toughened polylactide blends
Macromolecules, 2018Co-Authors: Tonghui Zhao, Wenqiang Yua, Yunxua Weng, Jianbing ZengAbstract:The use of soybean oil or its derivatives to toughen polylactide (PLA) usually leads to limited toughening efficiency, due to the incompatibility between toughening agents and parent PLA. Herein, we report a dynamic vulcanization method to toughen PLA using Sebacic Acid cured epoxidized soybean oil (VESO), a fully sustainable and biodegradable component. A series of Sebacic Acid cured epoxidized soybean oil precursors (SEPs) were prepared with different carboxyl/epoxy equivalent ratio (R), which consequently dictates the chemical structure and the morphology of PLA/VESO blends after the dynamic vulcanization. We demonstrated that the chemical structure of VESO plays a critical role in the compatibility, morphology, and toughness of the PLA/VESO blends. By optimizing the R-value, supertoughened PLA blends can be obtained, as evidenced by the significant improvement in the tensile toughness (up to 150.6 MJ/m3) and the impact strength (up to 542.3 J/m). The results of the toughening mechanism from the morpho...
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Relating Chemical Structure to Toughness via Morphology Control in Fully Sustainable Sebacic Acid Cured Epoxidized Soybean Oil Toughened Polylactide Blends
2018Co-Authors: Tonghui Zhao, Wenqiang Yua, Yunxua Weng, Jianbing ZengAbstract:The use of soybean oil or its derivatives to toughen polylactide (PLA) usually leads to limited toughening efficiency, due to the incompatibility between toughening agents and parent PLA. Herein, we report a dynamic vulcanization method to toughen PLA using Sebacic Acid cured epoxidized soybean oil (VESO), a fully sustainable and biodegradable component. A series of Sebacic Acid cured epoxidized soybean oil precursors (SEPs) were prepared with different carboxyl/epoxy equivalent ratio (R), which consequently dictates the chemical structure and the morphology of PLA/VESO blends after the dynamic vulcanization. We demonstrated that the chemical structure of VESO plays a critical role in the compatibility, morphology, and toughness of the PLA/VESO blends. By optimizing the R-value, supertoughened PLA blends can be obtained, as evidenced by the significant improvement in the tensile toughness (up to 150.6 MJ/m3) and the impact strength (up to 542.3 J/m). The results of the toughening mechanism from the morphology study confirm that the chemical structure of VESO is the key indicator of the toughening efficiency. For the PLA/VESO blends, at optimized R-value, the fracture energy can be dissipated efficiently through shear yielding of the PLA matrix induced by internal VESO cavitation to achieve supertoughness
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all plant oil derived epoxy thermosets with excellent comprehensive properties
Macromolecules, 2017Co-Authors: Xinyi Jian, Ming Wang, Jiahui Chen, Jianbing ZengAbstract:Epoxidized plant oil (EPO) thermosets usually exhibit poor performance due to the short, brittle, and amorphous cross-link structures. To fabricate fully biobased high performance EPO thermoset, we synthesized dicarboxyl-terminated polyamide1010 (NYL) oligomers from castor oil derived monomers, i.e., Sebacic Acid and decamethylene diamine, and used the NYL to cure epoxidized soybean oil (ESO) to fabricate all plant oil derived epoxy thermoset through a catalyst-free curing method. Chemorheological study indicated that the curing rate decreases with increasing NYL chain length. The cross-link density of the epoxy thermoset decreases while the crystallization enhances with increasing NYL chain length, which results in drastic enhancement in tensile strength, Young’s modulus, and elongation at break of the resultant thermosets, enabling those parameters to enhance by up to 59, 145, and 18 times, respectively, compared to Sebacic Acid cured ESO thermoset. The melting temperature and thus the heat resistance o...
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All Plant Oil Derived Epoxy Thermosets with Excellent Comprehensive Properties
2017Co-Authors: Xinyi Jian, Ming Wang, Jiahui Chen, Jianbing ZengAbstract:Epoxidized plant oil (EPO) thermosets usually exhibit poor performance due to the short, brittle, and amorphous cross-link structures. To fabricate fully biobased high performance EPO thermoset, we synthesized dicarboxyl-terminated polyamide1010 (NYL) oligomers from castor oil derived monomers, i.e., Sebacic Acid and decamethylene diamine, and used the NYL to cure epoxidized soybean oil (ESO) to fabricate all plant oil derived epoxy thermoset through a catalyst-free curing method. Chemorheological study indicated that the curing rate decreases with increasing NYL chain length. The cross-link density of the epoxy thermoset decreases while the crystallization enhances with increasing NYL chain length, which results in drastic enhancement in tensile strength, Young’s modulus, and elongation at break of the resultant thermosets, enabling those parameters to enhance by up to 59, 145, and 18 times, respectively, compared to Sebacic Acid cured ESO thermoset. The melting temperature and thus the heat resistance of the thermosets are also enhanced obviously with increasing NYL chain length. In addition, the thermosets show good durability and excellent thermal stability. With excellent comprehensive properties, the all plant oil derived epoxy thermosets could find some structural applications other than adhesive and coating
Robert Langer - One of the best experts on this subject based on the ideXlab platform.
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seeing through the interface poly e caprolactone surface modification of poly glycerol co Sebacic Acid membranes in adult porcine retinal explants
Journal of Tissue Engineering and Regenerative Medicine, 2017Co-Authors: Linnea Taylor, Robert Langer, Karin Arner, Martin E Kolewe, Christopher D Pritchard, Gillian Hendy, Fredrik GhoshAbstract:The purpose of this study was to investigate the adhesion properties and tissue reactions in an in vitro model of nanofabricated membranes emulating the vitreous cortex. Electrospinning was performed for either 5, 10 or 15 min to create various thicknesses of poly(e-caprolactone) (PCL) fibre mats on a poly(glycerol-co-Sebacic Acid) (PGS) surface. These were fused with adult porcine retinal explants, with the fibre side facing the inner retina, and cultured for 5 days. Adherence was assessed by macroscopic inspection, and morphological and immunohistochemical analysis was performed using haematoxylin and eosin (HE 15 min composite explants adhered only at focal points, were thin and showed extensive degenerative damage. The physical composition of nanofibre meshes is important for adhesion to the inner retina and has a significant impact on neuronal and glial survival in vitro. The results bearing on research involving retinal transplantation are discussed. (Less)
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synthesis of aliphatic polyesters by polycondensation using inorganic Acid as catalyst
Polymers for Advanced Technologies, 2011Co-Authors: Marina Sokolskypapkov, Robert Langer, Abraham J DombAbstract:An effective route for the synthesis of aliphatic polyesters made from adipic or Sebacic Acid and alkanediols, using inorganic Acid as a catalyst is reported. The monomer composition, reaction time, catalyst type, and reaction conditions were optimized to yield polyesters with weight average molecular weights of 23,000 for adipic Acid and 85,000 for Sebacic Acid-based polyesters. The polymers melt at temperatures of 52–65°C and possess melt viscosity in the range of 5600–19,400cP. This route represents an alternative method for producing aliphatic polyesters for possible use in the preparation of degradable disposable medical supplies.
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biodegradable xylitol based elastomers in vivo behavior and biocompatibility
Journal of Biomedical Materials Research Part A, 2010Co-Authors: Joost P Bruggeman, Christopher J Bettinger, Robert LangerAbstract:Biodegradable elastomers based on polycondensation reactions of xylitol with Sebacic Acid, referred to as poly(xylitol sebacate) (PXS) elastomers have recently been developed. We describe the in vivo behavior of PXS elastomers. Four PXS elastomers were synthesized, characterized, and compared with poly(L-lactic-co-glycolic Acid) (PLGA). PXS elastomers displayed a high level of structural integrity and form stability during degradation. The in vivo half-life ranged from approximately 3 to 52 weeks. PXS elastomers exhibited increased biocompatibility compared with PLGA implants.
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biodegradable poly polyol sebacate polymers
Biomaterials, 2008Co-Authors: Joost P Bruggeman, Christopher J Bettinger, Berendjan De Bruin, Robert LangerAbstract:Abstract We have developed a family of synthetic biodegradable polymers that are composed of structural units endogenous to the human metabolism, designated poly(polyol sebacate) (PPS) polymers. Material properties of PPS polymers can be tuned by altering the polyol monomer and reacting stiochiometric ratio of Sebacic Acid. These thermoset networks exhibited tensile Young's moduli ranging from 0.37 ± 0.08 to 378 ± 33 MPa with maximum elongations at break from 10.90 ± 1.37% to 205.16 ± 55.76%, and glass transition temperatures ranging from ∼7–46 °C. In vitro degradation under physiological conditions was slower than in vivo degradation rates observed for some PPS polymers. PPS polymers demonstrated similar in vitro and in vivo biocompatibility compared to poly( l -lactic-co-glycolic Acid) (PLGA).
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biodegradable xylitol based polymers
Advanced Materials, 2008Co-Authors: Christopher J Bettinger, Joost P Bruggeman, Christiaan Nijst, Daniel S Kohane, Robert LangerAbstract:Synthetic biodegradable polymers have made a considerable impact in various fields of biomedical engineering, such as drug delivery and tissue engineering. The design of synthetic biodegradable polymers for bioengineering purposes is challenging because of the application-specific constraints on the physical properties, including mechanical compliance and degradation rates, and the need for biocompatibility and low cytotoxicity. [1] The monomer selection frequently limits the range of required material properties. Our goal was to design a class of synthetic biopolymers based on a monomer that possesses a wide range of properties that are biologically relevant. This monomer ideally should be: (1) multifunctional to allow the formation of randomly crosslinked networks and a wide range of crosslinking densities; (2) nontoxic; (3) endogenous to the human metabolic system; (4) FDA approved; and (5) preferably inexpensive. We chose xylitol as it meets these criteria. We hypothesized that biodegradable polyesters could be obtained through copolymerization reactions with polycarboxylic Acids; the hydration of such biodegradable polymers could be controlled by tuning the different compositions and stoichiometry of the reacting monomer. Here, we describe xylitol-based polymers that realize this design. Polycondensation of xylitol with watersoluble citric Acid yielded biodegradable, water-soluble polymers. Acrylation ofthis polymer resulted in an elastomeric photocrosslinkable hydrogel. Polycondensation of xylitol with the water-insoluble Sebacic Acid monomer produced tough, biodegradable elastomers with tunable mechanical and degradation properties. These xylitol-based polymers exhibited excellent in vitro and in vivo biocompatibility compared to the well-characterized poly(L-lactic-co-glycolic Acid) (PLGA), and are promising biomaterials. Sebacic Acid (a metabolite in the oxidation of fatty Acids) and citric Acid (a metabolite in the Krebs cycle) were chosen as the reacting monomers for their proven biocompatibility; [2,3] they are also FDA-approved compounds. Polycondensation of xylitol with Sebacic Acid produced water-insoluble waxy prepolymers (termed PXS prepolymers). PXS prepolymers with a monomer ratio of xylitol: Sebacic Acid of 1:1 and 1:2 were synthesized and had a weight-average molecular weight (Mw) of 2443g/mol (Mn ¼1268g/mol, polydispersity index (PDI) 1.9) and 6202 g/mol (Mn ¼2255 g/mol, PDI2.7), respectively. The PXS prepolymers were melted into the desired form and cured by polycondensation (1208C, 40m Torr for 4 days, 1 Torr ¼133.3Pa) to yield low-modulus (PXS 1:1) and
Abraham J Domb - One of the best experts on this subject based on the ideXlab platform.
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recent advances in polyanhydride based biomaterials
Advanced Materials, 2018Co-Authors: Arijit Basu, Abraham J DombAbstract:This review focusses on recent developments of polyanhydrides, a class of degradable synthetic biopolymers. Polyanhydrides have been used as carriers for controlled delivery of drugs. A polyanhydride copolymer of carboxyphenoxy propane and Sebacic Acid has been used in Gliadel brain tumor implants for the controlled delivery of carmustine or bis-chloroethylnitrosourea. They are easy and inexpensive to synthesize (especially scale up). However, polyanhydrides possess a short shelf-life. Hydrolytic cleavage and anhydride interchanges lower their molecular weights during storage. One of the highlights in recent developments of polyanhydride chemistry is the discovery of alternating copolymers having extended shelf-life. Other highlights include their applications in biomedical electronics, vaccine delivery, and nano/micro particulate delivery systems. This review examines approaches for polyanhydride synthesis followed by their recent developments in biomedical applications.
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stable polyanhydride synthesized from Sebacic Acid and ricinoleic Acid
Journal of Controlled Release, 2017Co-Authors: Moran Haimzada, Arijit Basu, Tal Hagigit, Ron Schlinger, Michael Grishko, Alexander Kraminsky, Ezra Hanuka, Abraham J DombAbstract:Poly(anhydride) are unstable and prone to hydrolytic degradation and depolymerisation via anhydride interchange. They are stored at -20°C, packed under inert atmosphere until use. We synthesized a new poly(anhydride) from ricinoleic (RA) and Sebacic (SA) Acid with alternating ester-anhydride structure that is stable at 25°C for over 18months. The copolymer is also stable in chloroform solution and under γ-irradiation. The polymer hydrolyses through anhydride cleavage lasting ~7days to form oligoesters, which are stable for >30days. The release of gentamycin from the synthesized alternate polymer matrix is sustained compared to the random copolymer.
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Alternating Poly(ester-anhydride) by Insertion Polycondensation
2016Co-Authors: Moran Haim-zada, Arijit Basu, Tal Hagigit, Ron Schlinger, Michael Grishko, Alexander Kraminsky, Ezra Hanuka, Abraham J DombAbstract:We report on a synthetic method where polyanhydride is used as starting material and the ester monomers are inserted through complete esterification, leading to an alternating ester-anhydride copolymer. The molar ratio of ricinoleic Acid (RA) and Sebacic Acid (SA) was optimized until polySebacic Acid is completely converted to carboxylic Acid-terminated RA-SA and RA-SA-RA ester-dicarboxylic Acids. These dimers and trimers were activated with acetic anhydride, polymerized under heat and vacuum to yield alternating RA-SA copolymer. The resulting alternating poly(ester-anhydride) have the RA at regular intervals. The regular occurrences of RA side chains prevent anhydride interchange, enhancing hydrolytic stability, which allows storage of the polymer at room temperature
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preparation and in vitro characterization of poly Sebacic Acid co ricinoleic Acid based tamoxifen citrate loaded microparticles for breast cancer
Journal of Applied Polymer Science, 2011Co-Authors: Jagadeesh G Hiremath, Abraham J Domb, C G Rudani, R V Suthar, N S KhamarAbstract:This study was aimed to develop an injectable polymeric drug delivery system for tamoxifen citrate (TC) using poly(Sebacic Acid-co-ricinoleic Acid) [poly(SA-RA) 70 : 30 w/w] as a drug carrier for the treatment of estrogen receptor positive breast cancer. Injectable biodegradable microparticles of TC were produced by solvent displacement technique of microencapsulation and were characterized by surface morphology (scanning electron microscopy), particle size, size distribution, physical and chemical interaction (Fourier transform infrared), nature and physical state of drug [DSC and X-ray diffraction (XRD)], and in vitro release studies. TC loading over different concentrations was analyzed by high performance liquid chromatography (HPLC) technique. Polyanhydride microparticles obtained after lyophilization were nearly spherical in shape with smooth surface and size less than 2.5 μm. TC was dispersed in the form of amorphous state, and TC remains intact and stable during the process of microencapsulation. In vitro drug release studies demonstrated prolonged controlled release of TC with zero-order kinetics. Stability studies revealed that the production process of microparticles itself did not affect the chemical stability of the drug and polymer forming the particle matrix. Significant difference in drug release capacity was observed in microparticles with different drug loadings, and the drug release was more sustained in microparticles prepared with high TC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
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synthesis of aliphatic polyesters by polycondensation using inorganic Acid as catalyst
Polymers for Advanced Technologies, 2011Co-Authors: Marina Sokolskypapkov, Robert Langer, Abraham J DombAbstract:An effective route for the synthesis of aliphatic polyesters made from adipic or Sebacic Acid and alkanediols, using inorganic Acid as a catalyst is reported. The monomer composition, reaction time, catalyst type, and reaction conditions were optimized to yield polyesters with weight average molecular weights of 23,000 for adipic Acid and 85,000 for Sebacic Acid-based polyesters. The polymers melt at temperatures of 52–65°C and possess melt viscosity in the range of 5600–19,400cP. This route represents an alternative method for producing aliphatic polyesters for possible use in the preparation of degradable disposable medical supplies.
Tonghui Zhao - One of the best experts on this subject based on the ideXlab platform.
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relating chemical structure to toughness via morphology control in fully sustainable Sebacic Acid cured epoxidized soybean oil toughened polylactide blends
Macromolecules, 2018Co-Authors: Tonghui Zhao, Wenqiang Yua, Yunxua Weng, Jianbing ZengAbstract:The use of soybean oil or its derivatives to toughen polylactide (PLA) usually leads to limited toughening efficiency, due to the incompatibility between toughening agents and parent PLA. Herein, we report a dynamic vulcanization method to toughen PLA using Sebacic Acid cured epoxidized soybean oil (VESO), a fully sustainable and biodegradable component. A series of Sebacic Acid cured epoxidized soybean oil precursors (SEPs) were prepared with different carboxyl/epoxy equivalent ratio (R), which consequently dictates the chemical structure and the morphology of PLA/VESO blends after the dynamic vulcanization. We demonstrated that the chemical structure of VESO plays a critical role in the compatibility, morphology, and toughness of the PLA/VESO blends. By optimizing the R-value, supertoughened PLA blends can be obtained, as evidenced by the significant improvement in the tensile toughness (up to 150.6 MJ/m3) and the impact strength (up to 542.3 J/m). The results of the toughening mechanism from the morpho...
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Relating Chemical Structure to Toughness via Morphology Control in Fully Sustainable Sebacic Acid Cured Epoxidized Soybean Oil Toughened Polylactide Blends
2018Co-Authors: Tonghui Zhao, Wenqiang Yua, Yunxua Weng, Jianbing ZengAbstract:The use of soybean oil or its derivatives to toughen polylactide (PLA) usually leads to limited toughening efficiency, due to the incompatibility between toughening agents and parent PLA. Herein, we report a dynamic vulcanization method to toughen PLA using Sebacic Acid cured epoxidized soybean oil (VESO), a fully sustainable and biodegradable component. A series of Sebacic Acid cured epoxidized soybean oil precursors (SEPs) were prepared with different carboxyl/epoxy equivalent ratio (R), which consequently dictates the chemical structure and the morphology of PLA/VESO blends after the dynamic vulcanization. We demonstrated that the chemical structure of VESO plays a critical role in the compatibility, morphology, and toughness of the PLA/VESO blends. By optimizing the R-value, supertoughened PLA blends can be obtained, as evidenced by the significant improvement in the tensile toughness (up to 150.6 MJ/m3) and the impact strength (up to 542.3 J/m). The results of the toughening mechanism from the morphology study confirm that the chemical structure of VESO is the key indicator of the toughening efficiency. For the PLA/VESO blends, at optimized R-value, the fracture energy can be dissipated efficiently through shear yielding of the PLA matrix induced by internal VESO cavitation to achieve supertoughness
Joost P Bruggeman - One of the best experts on this subject based on the ideXlab platform.
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biodegradable xylitol based elastomers in vivo behavior and biocompatibility
Journal of Biomedical Materials Research Part A, 2010Co-Authors: Joost P Bruggeman, Christopher J Bettinger, Robert LangerAbstract:Biodegradable elastomers based on polycondensation reactions of xylitol with Sebacic Acid, referred to as poly(xylitol sebacate) (PXS) elastomers have recently been developed. We describe the in vivo behavior of PXS elastomers. Four PXS elastomers were synthesized, characterized, and compared with poly(L-lactic-co-glycolic Acid) (PLGA). PXS elastomers displayed a high level of structural integrity and form stability during degradation. The in vivo half-life ranged from approximately 3 to 52 weeks. PXS elastomers exhibited increased biocompatibility compared with PLGA implants.
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biodegradable poly polyol sebacate polymers
Biomaterials, 2008Co-Authors: Joost P Bruggeman, Christopher J Bettinger, Berendjan De Bruin, Robert LangerAbstract:Abstract We have developed a family of synthetic biodegradable polymers that are composed of structural units endogenous to the human metabolism, designated poly(polyol sebacate) (PPS) polymers. Material properties of PPS polymers can be tuned by altering the polyol monomer and reacting stiochiometric ratio of Sebacic Acid. These thermoset networks exhibited tensile Young's moduli ranging from 0.37 ± 0.08 to 378 ± 33 MPa with maximum elongations at break from 10.90 ± 1.37% to 205.16 ± 55.76%, and glass transition temperatures ranging from ∼7–46 °C. In vitro degradation under physiological conditions was slower than in vivo degradation rates observed for some PPS polymers. PPS polymers demonstrated similar in vitro and in vivo biocompatibility compared to poly( l -lactic-co-glycolic Acid) (PLGA).
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biodegradable xylitol based polymers
Advanced Materials, 2008Co-Authors: Christopher J Bettinger, Joost P Bruggeman, Christiaan Nijst, Daniel S Kohane, Robert LangerAbstract:Synthetic biodegradable polymers have made a considerable impact in various fields of biomedical engineering, such as drug delivery and tissue engineering. The design of synthetic biodegradable polymers for bioengineering purposes is challenging because of the application-specific constraints on the physical properties, including mechanical compliance and degradation rates, and the need for biocompatibility and low cytotoxicity. [1] The monomer selection frequently limits the range of required material properties. Our goal was to design a class of synthetic biopolymers based on a monomer that possesses a wide range of properties that are biologically relevant. This monomer ideally should be: (1) multifunctional to allow the formation of randomly crosslinked networks and a wide range of crosslinking densities; (2) nontoxic; (3) endogenous to the human metabolic system; (4) FDA approved; and (5) preferably inexpensive. We chose xylitol as it meets these criteria. We hypothesized that biodegradable polyesters could be obtained through copolymerization reactions with polycarboxylic Acids; the hydration of such biodegradable polymers could be controlled by tuning the different compositions and stoichiometry of the reacting monomer. Here, we describe xylitol-based polymers that realize this design. Polycondensation of xylitol with watersoluble citric Acid yielded biodegradable, water-soluble polymers. Acrylation ofthis polymer resulted in an elastomeric photocrosslinkable hydrogel. Polycondensation of xylitol with the water-insoluble Sebacic Acid monomer produced tough, biodegradable elastomers with tunable mechanical and degradation properties. These xylitol-based polymers exhibited excellent in vitro and in vivo biocompatibility compared to the well-characterized poly(L-lactic-co-glycolic Acid) (PLGA), and are promising biomaterials. Sebacic Acid (a metabolite in the oxidation of fatty Acids) and citric Acid (a metabolite in the Krebs cycle) were chosen as the reacting monomers for their proven biocompatibility; [2,3] they are also FDA-approved compounds. Polycondensation of xylitol with Sebacic Acid produced water-insoluble waxy prepolymers (termed PXS prepolymers). PXS prepolymers with a monomer ratio of xylitol: Sebacic Acid of 1:1 and 1:2 were synthesized and had a weight-average molecular weight (Mw) of 2443g/mol (Mn ¼1268g/mol, polydispersity index (PDI) 1.9) and 6202 g/mol (Mn ¼2255 g/mol, PDI2.7), respectively. The PXS prepolymers were melted into the desired form and cured by polycondensation (1208C, 40m Torr for 4 days, 1 Torr ¼133.3Pa) to yield low-modulus (PXS 1:1) and