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Blending polylactide (PLA) with poly(propylene carbonate) offers potential solution to mitigate the greenhouse effect due to PLA's lower carbon dioxide (CO2) emissions and its use of CO2 as a monomer in PPC synthesis. In this investigation, a series of PLA and PPC blends were prepared using the solvent casting method to address their respective weaknesses. The blends exhibited partial compatibility, as evidenced by a noticeable shift in the glass transition temperatures toward each other. Tensile testing revealed that the incorporation of PPC improved the elongation properties of PLA. The degradation characteristics of the blend films were evaluated based on changes in the monolayer's occupied area, the properties of the bulk film, and changes in surface morphology. Results indicated that PPC content accelerated hydrolytic degradation but slowed enzymatic degradation in the blends. Hydrolytic and enzymatic degradation significantly impacted the mechanical properties of PLA/PPC blends, prolonging the degradation process through chain scission. [ABSTRACT FROM AUTHOR]

Polypropylene carbonate (PPC) is a promising candidate of substrate materials used for human wearable devices due to its excellent ductility and biocompatibility. However, PPC is prone to be deformed, thus resulting in poor shape recovery property. One effective solution is to construct composites. In this work, poly (tannic acid) with Fe3+ (FPTA) @ graphene oxide (GO) was added to fabricate FPTA@GO/PPC composites. The results show that FPTA@GO can construct a tight network of hydrogen bonds into PPC to improve shape memory and self‐healing properties. By varying the FPTA@GO content, the composites exhibit tunable shape memory property. Dynamic mechanical analysis confirms that FPTA@GO/PPC composites show better shape memory properties compared with pure PPC. 5 wt% FPTA@GO/PPC composite demonstrates superior shape fixation ratio (Rf = 99%) as well as superior shape recovery ratio (Rr = 94%) in 37°C. Moreover, 5 wt% FPTA@GO/PPC composite possesses great self‐healing efficiency of 81% and tensile strength (17.2 MPa). The UV absorption capacity of 5 wt% FPTA@GO/PPC is increased by 150% (far and mid‐UV regions) and 400% (near‐UV region) compared with pure PPC. Thus, FPTA@GO/PPC composites have potential applications in developing shape memory, self‐healing, and UV‐resistant materials for human wearable devices. [ABSTRACT FROM AUTHOR]

A highly active zinc glutarate-double metal cyanide (DMC) composite catalyst (ZnGA/Zn-CrDMC) was designed for the carbon dioxide (CO2) and propylene oxide (PO) copolymerization reaction. The composite catalyst was synthesized in a rheological phase reaction and characterized using Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The synthesized composite catalysed the solvent free reactions of PO and CO2 to afford biodegradable polypropylene carbonate (PPC) copolymer. 1H NMR,13C NMR, FT-IR and ESI-TOF mass spectrometry measurements were employed to confirm the characteristics of the PPC produced. Under optimal reaction conditions (50 bar CO2, 70 °C, 24 h), the ZnGA-Zn3[Cr(CN)6]2 composite displayed higher catalytic activities in the copolymerization reactions than the individual catalysts. The ZnGA:Zn3[Cr(CN)6]2 ratio of 15:1 gave PPC yield of 47.9 g polymer/g cat compared to ZnGA that produced 42.6 g polymer/ g cat in 24 h. In addition, the PPC produced from the composite catalyst displayed higher carbonate linkage content (Fc = 85.4 %) compared to the value of Fc = 33.9 %. obtained using the Zn3[Cr(CN)6]2 catalyst. Similaly, the composite catalsyt produced PPC with molecular weight of 4200 g/mol and narrow polydispersity index of 2.2. The resultant PPC copolymer displayed good thermal stability, exhibiting a high degradation temperatures (TGA-10%) of 229 °C and complete decomposition at 350 °C.

Blends of poly(lactic acid) (PLA) with poly(propylene carbonate) (PPC) are currently in the phase of intensive study due to their promising properties and environmentally friendly features. Intensive study and further commercialization of PPC-based polymers or their blends, as usual, will soon face the problem of their waste occurring in the environment, including soil. For this reason, it is worth comprehensively studying the degradation rate of these polymers over a long period of time in soil and, for comparison, in phosphate buffer to understand the difference in this process and evaluate the potential application of such materials toward agrochemical and agricultural purposes. The degradation rate of the samples was generally accompanied by weight loss and a decrease in molecular weight, which was facilitated by the presence of PPC. The incubation of the samples in the aqueous media yielded greater surface erosions compared to the degradation in soil, which was attributed to the leaching of the low molecular degradation species out of the foils. The phytotoxicity study confirmed the no toxic impact of the PPC on tested plants, indicating it as a "green" material, which is crucial information for further, more comprehensive study of this polymer toward any type of sustainable application. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT)/poly (propylene carbonate) (PPC) multi-phase blends were prepared by melt processing technique under the presence of compatibilizer with various composition. The effect on the physical and the mechanical property with/without ESO was characterized with spectrophotometric analysis, mechanical properties, thermal properties, rheological properties and barrier properties, and the structure-properties relationship was assessed. ​​The functional groups of PPC were found to effective to improve an interaction with carboxyl/hydroxyl group of PLA/PBAT binary blends to enhance the mechanical and physical properties on multi-phase blend system. The presence of PPC in PLA/PBAT blend affected the reduction of voids on the interface phase resulting in enhancing the oxygen barrier properties. With addition of ESO, the compatibility of ternary blend was found to be enhanced since the epoxy group of ESO reacted with the carboxyl/hydroxyl group of PLA, PBAT, and PPC, and under the condition with critical content of 4 phr of ESO, the elongation behavior dramatically increased as compared to that of blends without ESO while affecting reduction of oxygen barrier properties. The effect of ESO as a compatibilizer was clearly observed from the overall performances of ternary blends, and the potential feasibility of the PLA/PBAT/PPC ternary blends as packaging materials was confirmed at this study. [ABSTRACT FROM AUTHOR]

This study aimed to obtain a compound with superior shape memory properties and a transfer temperature close to human body temperature. Therefore, by precise adjusting the combination of polypropylene carbonate (PPC), polycaprolactone (PCL) and graphene nanoplatelets (GNPs), an attempt was made to reach a transfer temperature of 37 0C.To improve the dispersion and performance of graphene nanoplatelets, its chemical modification with polyethylene glycol (PEG) was considered. X-ray energy diffraction spectroscopy analysis (EDX), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) was used to confirm the surface modification of nanoparticles. PCL/PPC blends and their nanocomposites were prepared via solution casting with different ratios (PCL/PPC: 10/90, 15/85, 20/80 w/w) in the presence of 0.5, 1, 1.5 phr of modified GNPs. Various techniques such as differential scanning calorimetry (DSC), scanning electron microscope (SEM), and dynamic mechanical thermal analysis (DMTA) were used to characterize samples. A traction device equipped with a temperature-controlled chamber was used to induce shape memory. The shape memory behavior of these blends was discovered to be highly dependent on their components. Samples containing 10 wt% PCL with 0.5 to 1 phr of modified GNPs achieved an optimal shape fixing ratio (Rf) and recovery ratio (Rr) with a memory transfer temperature close to human body temperature. [ABSTRACT FROM AUTHOR]

Blends of poly(lactic acid) (PLA) with poly(propylene carbonate) (PPC) are currently in the phase of intensive study due to their promising properties and environmentally friendly features. Intensive study and further commercialization of PPC-based polymers or their blends, as usual, will soon face the problem of their waste occurring in the environment, including soil. For this reason, it is worth comprehensively studying the degradation rate of these polymers over a long period of time in soil and, for comparison, in phosphate buffer to understand the difference in this process and evaluate the potential application of such materials toward agrochemical and agricultural purposes. The degradation rate of the samples was generally accompanied by weight loss and a decrease in molecular weight, which was facilitated by the presence of PPC. The incubation of the samples in the aqueous media yielded greater surface erosions compared to the degradation in soil, which was attributed to the leaching of the low molecular degradation species out of the foils. The phytotoxicity study confirmed the no toxic impact of the PPC on tested plants, indicating it as a “green” material, which is crucial information for further, more comprehensive study of this polymer toward any type of sustainable application.

[Display omitted] • A simple yet effective strategy is employed to elevate the glass transition temperature of polypropylene carbonate. • Hydrogen bond interactions are visually assessed using Gromacs through molecular dynamics simulations. • The PPC/CM nanocomposite and foam demonstrate remarkable tensile strength and exceptional sterilization efficiency. Biodegradable polypropylene carbonate (PPC) has garnered significant attention for its commendable biodegradability and its role in mitigating the greenhouse effect. However, the inherent drawback of PPC, its low glass transition temperature (T g), severely restricts its widespread use, especially at room temperature. In this study, we explore the utilization of MXene-OH/CNTs-OH (CM) hybrids, which encompass hydroxylated one-dimensional carbon nanotubes (CNTs-OH) and the two-dimensional layered structure of Ti 3 C 2 (MXene-OH), to enhance the properties of PPC through hydrogen bonding complexation. By adjusting the content of nanofillers, the resulting PPC/CM composites demonstrate improved T g , mechanical strength, and exceptional capability in supercritical foaming. Both experimental and theoretical analyses confirm that the CM crosslinking mechanism significantly elevates the T g of the composite to 37.3 °C, while also enhancing tensile strength by 23.7% and antibacterial activity by 99.6%. This study presents a straightforward and practical method for developing functionalized, sustainable polymer foams with enhanced characteristics, poised for a diverse range of applications. [ABSTRACT FROM AUTHOR]

Objective：To prepare the novel fluoride loaded poly(prolylene carbonate)(PPC)/sodium fluoride (NaF) dental patch based on PPC and explore its remineralization property and in vitro cytotoxicity, and to clarify its effect of fluorine-containing patches with different concentrations of fluoride in promoting the remineralization of demineralized enamel, and to provide the reference for its clinical application. Methods：The PPC/NaF dental patch with different mass fractions of sodium fluoride(0, 0. 5%, 2. 5%, and 5.0%)were prepared by melt-blending method. The enamel blocks were prepared with extracorporeal tooth and randomly divided into PPC group, 0. 5%PPC/NaF group, 2. 5%PPC/NaF group, and 5.0%PPC/NaF group according to different contents of fluoride in the dental patches, and there were 10 samples in each group. The morphology of surface of enamel specimens was observed under scanning electron microscope (SEM), the microhardness of the enamel surface before and after demineralization and after remineralization was measured by microhardness tester, and the microhardness recovery percentage(SMHR)was calculated. The mouse fibroblast L929 cells were co-cultured with the PPC/NaF dental patch extract, and CCK-8 test was used to detect the relative proliferation rate(RGR)of the fibroblast L929 cells of the mice in various groups, and its cytotoxicity level was evaluated. Results：The microhardness of the enamel specimens in various groups after demineralization was significantly lower than that before demineralization(P<0.05). After being treated with PPC/NaF tooth patches with different contents of sodium fluoride, the microhardness of the enamel specimens in various groups was significantly higher than that before remineralization(P<0.05), but still lower than that before demineralization(P<0.05). The SMHR of enamel specimens in each group from high to low was 5.0% PPC/NaF group, 2. 5% PPC/NaF group, 0. 5% PPC/NaF group, and PPC group. The SEM results showed that the number of pores on the surface of the enamel specimens in PPC group was still large, and the irregular granular sediments were seen；in 0. 5%PPC/NaF group, the number of pores on the enamel surface was decreased significantly, and the obvious enamel collapse was still seen on the surface and mineral crystal deposition was loose and uneven；in 2. 5% PPC/NaF group, there were almost no pores on the enamel surface, and the enamel surface was regular and covered with a large number of needle-like crystals, which were densely arranged；in 5.0% PPC/NaF group, the enamel surface was covered with a large number of needle-like or irregular granular crystals and layered sediments were seen in some areas. Compared with PPC group, the RGR of the fibroblast L929 cells of the mice in 5.0% PPC/NaF group was decreased significantly(P<0.05). The RGR of the fibroblast L929 cells after treated with PPC/NaF tooth patches with different contents of fluoride in various groups was greater than 75%, and the cytotoxicity grade was 0 or 1. Conclusion：PPC/NaF dental patch can effectively promote the demineralization of the demineralized enamel without cytotoxicity；with the increasing of fluorine concentration, its remineralization is also enhanced. [ABSTRACT FROM AUTHOR]

The melt-free radical grafting of glycidyl methacrylate (GMA) onto poly (lactic acid) (PLA) with styrene (St), α-methylstyrene (AMS), and epoxy resin (EP) as comonomers in a twin-screw extruder was used to prepare PLA-g-GMA graft copolymers. The prepared graft copolymers were then used as compatibilizers to prepare PLA/PPC/PLA-g-GMA blends by melt blending with PLA and polypropylene carbonate (PPC), respectively. The effects of different comonomers in the PLA-g-GMA graft copolymers on the thermal, rheological, optical, and mechanical properties and microstructure of the blends were studied. It was found that the grafting degree of PLA-g-GMA graft copolymers was increased to varying degrees after the introduction of comonomers in the PLA-g-GMA grafting reaction system. When St was used as the comonomer, the grafting degree of the PLA-g-GMA graft copolymer increased most significantly, from 0.8 to 1.6 phr. St as a comonomer also most improved the compatibility between PLA and PPC, and the haze of the blends was reduced while maintaining high transmittance. In addition, the PLA-g-GMA graft copolymer with the introduction of St as a comonomer significantly improved the impact toughness of the blends, while the thermal stability and tensile strength of the blends remained largely unchanged. [ABSTRACT FROM AUTHOR]

The greenhouse effect and plastic pollution caused by the accumulation of plastics have led to a global concern for environmental protection, as well as the development and application of biodegradable materials. Polypropylene carbonate (PPC) is a biodegradable polymer with the function of "carbon sequestration", which has the potential to mitigate the greenhouse effect and the plastic crisis. It has the advantages of good ductility, oxygen barrier and biocompatibility. However, the mechanical and thermal properties of PPC are poor, especially the low thermal degradation temperature, which limits its industrial use. In order to overcome this problem, PPC can be modified using environmentally friendly materials, which can also reduce the cost of PPC-based products to a certain extent and enhance their competitiveness in terms of improving their mechanical and thermal properties. In this paper, we present different perspectives on the synthesis, properties, degradation, modification and post-modification applications of PPC. The modification part mainly introduces the influence of inorganic materials, natural polymer materials and degradable polymers on the performance of PPC. It is hoped that this work will serve as a reference for the early promotion of PPC. [ABSTRACT FROM AUTHOR]

This study deals with investigating the morphological, mechanical, dynamic-mechanical, and shape memory properties of novel Polycaprolactone (PCL)/polypropylene carbonate (PPC)-based nanocomposite blends reinforced with GlycidylIsobutyl-functionalized polyhedral oligomeric silsesquioxane (G-POSS) nanoparticles. Scanning Electron Microscopy images of blends revealed droplet-matrix morphology with distinct domains where increased PPC content led to increased number and size for PCC droplets. Introducing nanoparticles by compatibilizing the blends changed the droplet-matrix morphology to a co-continuous one and consequently improved mechanical and shape memory properties. Distribution of nanoparticles up to 5 wt% remained uniform for samples with higher PPC contents. The shape memory analysis results revealed that the shape memory properties were highly dependent on the mixing ratio of polymers and nanoparticles content. Besides, introducing the nanoparticles caused a considerable reduction in the recovery time. Finally, the composition with a PCL/PPC ratio of 20/80 as well 5 wt% G-POSS content was suggested as the sample with optimum shape memory properties with Tg = 35 °C, fixity ratio = 98%, recovery ratio = 95%, and the remarkable recovery time of 17 seconds, enjoying the elastic modulus of 772 MPa, the tensile strength of 85.2 MPa, and elongation at break of 450% that shows the high potential of this blend for different applications, especially in the biomedical field.

• Water treatment improves the crystallinity and surface area of ZnGA. • The cyanide-modification of water-activated zinc glutarate (ZnGA) enhances the catalytic performance. • High molecular weight poly(propylene carbonate) was synthesized by ZnGA/DMC catalysts. Zinc glutarate (ZnGA) is a prominent catalyst for the production of CO 2 -based poly(propylene carbonate). The original catalysts, ZnO-GA (Cat 1) and ZnAc 2 -GA (Cat 3), were prepared using ZnO and ZnAc 2 as Zn sources, respectively. ZnO-GA-H 2 O (Cat 2) and ZnAc 2 -GA-H 2 O (Cat 4) were prepared by water treatment of Cat 1 and Cat 3 , respectively. After water treatment, both Cat 2 and Cat 4 showed enhanced performance for copolymerization of CO 2 and propylene oxide. The characterizations demonstrated that H 2 O is a critical component that not only improves the crystallinity and external surface area of ZnGA, but also increases the number of surface Zn-OH groups. By adding a portion of cyanide, further modification on Cat 4 resulted in a group of ZnAc 2 -GA-H 2 O/DMC catalysts (m-Cat 4). The polymerization reached a high yield of 1729 g poly/g Cat and a selectivity of 98.7 % at molar ratio of DMC/ZnGA = 1: 10 (t = 24 h; T = 70 °C; P = 4 MPa). The modified ZnGA/DMC catalyst exhibited remarkable yield and selectivity for the copolymerization of CO 2 and propylene oxide to produce high molecular weight alternating copolymers (2.3 × 105 g/mol). [Display omitted] [ABSTRACT FROM AUTHOR]

Polypropylene carbonate (PPC)/polybutylene succinate (PBS) blends were prepared by melt-blending with terminal epoxy-based hyperbranched polymers (EHBP) as modifier. The thermal properties, mechanical properties, rheological properties and fracture morphology were characterized by dynamic thermomechanical analyzer (DMA), thermogravimetric analyzer (TGA), electronic universal testing machine, rotating rheometer and scanning electron microscope (SEM). Upon addition of EHBP, the difference between the glass transition temperature of PPC and PBS became smaller, indicating the compatibility of PPC and PBS were improved by EHBP. Furthermore, by adding 0.5phr of EHBP, the impact strength increased from 9.55 to 17.31 kJ/m2, the elongation at break increased from 136.29 to 204.39%, and the tensile strength increased from 10.00 to 16.84 MPa. The fracture surface of the PPC/PBS blends became rough with the increase of EHBP, even with large filamentous structures and tiny holes, which further demonstrated that EHBP acted as an excellent toughening effect on PPC/PBS. Gel content analysis confirmed that both physical and chemical micro-crosslinking were formed after incorporation of EHBP. [ABSTRACT FROM AUTHOR]

There has been a significant increase in the failure of pipes used for recirculating hot water systems installed in hospitals, apartment blocks, and hotels in recent years. The rise has occurred as these systems have increased in popularity, and thermostatic mixing valves have made the higher operating temperatures in recirculating systems safe. A common theme tends to be the continuous flow of water above 65°C (150°F) at velocities that have been found acceptable for non-continuous flow. Failures have been experienced in pipes made from both copper and polypropylene random copolymer. Explanations have been slow to emerge and are still subject to debate, particularly as to the initiating causes of pin-hole corrosion (one of the more common modes of failure). Since it is not possible to view the initiation of the pin hole, proof of the cause of the initiation is still unknown. There are indications from consistent correlations between operating conditions and the onset of pin-holing corrosion that are used by authorities as the basis of modifications to design and installation standards to minimize occurrence. This paper will cover some of the background, myths, and current thinking on the causes of the problem in both copper and polypropylene from the point of view of a forensic engineer trying to make sense of uncertain science and the complications of a problem that is transdisciplinary in nature. [ABSTRACT FROM AUTHOR]

The melt-free radical grafting of glycidyl methacrylate (GMA) onto poly (lactic acid) (PLA) with styrene (St), α-methylstyrene (AMS), and epoxy resin (EP) as comonomers in a twin-screw extruder was used to prepare PLA-g-GMA graft copolymers. The prepared graft copolymers were then used as compatibilizers to prepare PLA/PPC/PLA-g-GMA blends by melt blending with PLA and polypropylene carbonate (PPC), respectively. The effects of different comonomers in the PLA-g-GMA graft copolymers on the thermal, rheological, optical, and mechanical properties and microstructure of the blends were studied. It was found that the grafting degree of PLA-g-GMA graft copolymers was increased to varying degrees after the introduction of comonomers in the PLA-g-GMA grafting reaction system. When St was used as the comonomer, the grafting degree of the PLA-g-GMA graft copolymer increased most significantly, from 0.8 to 1.6 phr. St as a comonomer also most improved the compatibility between PLA and PPC, and the haze of the blends was reduced while maintaining high transmittance. In addition, the PLA-g-GMA graft copolymer with the introduction of St as a comonomer significantly improved the impact toughness of the blends, while the thermal stability and tensile strength of the blends remained largely unchanged.

This study deals with investigating the morphological, mechanical, dynamic-mechanical, and shape memory properties of novel Polycaprolactone (PCL)/polypropylene carbonate (PPC)-based nanocomposite blends reinforced with GlycidylIsobutyl-functionalized polyhedral oligomeric silsesquioxane (G-POSS) nanoparticles. Scanning Electron Microscopy images of blends revealed droplet-matrix morphology with distinct domains where increased PPC content led to increased number and size for PCC droplets. Introducing nanoparticles by compatibilizing the blends changed the droplet-matrix morphology to a co-continuous one and consequently improved mechanical and shape memory properties. Distribution of nanoparticles up to 5 wt% remained uniform for samples with higher PPC contents. The shape memory analysis results revealed that the shape memory properties were highly dependent on the mixing ratio of polymers and nanoparticles content. Besides, introducing the nanoparticles caused a considerable reduction in the recovery time. Finally, the composition with a PCL/PPC ratio of 20/80 as well 5 wt% G-POSS content was suggested as the sample with optimum shape memory properties with Tg = 35 °C, fixity ratio = 98%, recovery ratio = 95%, and the remarkable recovery time of 17 seconds, enjoying the elastic modulus of 772 MPa, the tensile strength of 85.2 MPa, and elongation at break of 450% that shows the high potential of this blend for different applications, especially in the biomedical field. [ABSTRACT FROM AUTHOR]

The greenhouse effect and plastic pollution caused by the accumulation of plastics have led to a global concern for environmental protection, as well as the development and application of biodegradable materials. Polypropylene carbonate (PPC) is a biodegradable polymer with the function of “carbon sequestration”, which has the potential to mitigate the greenhouse effect and the plastic crisis. It has the advantages of good ductility, oxygen barrier and biocompatibility. However, the mechanical and thermal properties of PPC are poor, especially the low thermal degradation temperature, which limits its industrial use. In order to overcome this problem, PPC can be modified using environmentally friendly materials, which can also reduce the cost of PPC-based products to a certain extent and enhance their competitiveness in terms of improving their mechanical and thermal properties. In this paper, we present different perspectives on the synthesis, properties, degradation, modification and post-modification applications of PPC. The modification part mainly introduces the influence of inorganic materials, natural polymer materials and degradable polymers on the performance of PPC. It is hoped that this work will serve as a reference for the early promotion of PPC.

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A strategy that uses carbon monoxide (CO) as a molecular trigger to switch the polymerization mechanism of a cobalt Salen complex [salen=(R,R)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamine] from ring‐opening copolymerization (ROCOP) of epoxides/anhydrides to organometallic mediated controlled radical polymerization (OMRP) of acrylates is described. The key phenomenon is a rapid and quantitative insertion of CO into the Co−O bond, allowing for in situ transformation of the ROCOP active species (Salen)CoIII‐OR into the OMRP photoinitiator (Salen)CoIII‐CO2R. The proposed mechanism, which involves CO coordination to (Salen)CoIII‐OR and subsequent intramolecular rearrangement via migratory insertion has been rationalized by DFT calculations. Regulated by both CO and visible light, on‐demand sequence control can be achieved for the one‐pot synthesis of polyester‐b‐polyacrylate diblock copolymers (Đ<1.15). [ABSTRACT FROM AUTHOR]

• A facile and clean strategy is used to enhance the glass transition temperature of polypropylene carbonate. • The interaction and hydrogen bonding are determined via GROMACS based on molecular dynamics simulations. • The guanidine phosphate functioning on the polypropylene carbonate with excellent flame retardany. • The polymer composites show good mechanical strength while maintaining its intrinsic transparency nature. It is a challenge all the time to prepare transparent flame retardant polymer composites. In this contribution, a biodegradable carbon dioxide derived copolymer polypropylene carbonate (PPC) has been chosen considering its signality for human environmental protection. Nevertheless, the low glass transition temperature (T g) of PPC limits its practical applications. Herein, polylactic acid (PLA) and flame retardant guanidine phosphate (GP) were selected to obtain PPC composites by the interaction of intermolecular hydrogen bonds (H-bonds). The properties of PPC/PLA/GP composites were systematically studied. The test results showed that GP can be uniformly dispersed and contributed to the composites with enhanced T g and flame-retardant properties. As a model system, 3 wt.% of GP enabled the PPC/PLA/GP-3 composites with T g of 60.0 ℃, UL-94 grade of V-0, limiting oxygen index (LOI) of 30.8 %, and a significant reduction of THR (13 %), pHRR (32 %), and pCO (84 %), respectively. Besides that, the introduction of GP displayed slight influences on the intrinsic transparency nature of PPC/PLA. This study provided a facile approach for solving the bottleneck of PPC for advanced applications. [ABSTRACT FROM AUTHOR]

Using biodegradable polypropylene carbonate (PPC) as the polymer matrix and 5 to 25 wt% content of spent coffee bean powder (SCBP) as filler, completely biodegradable composite films of PPC/SCBP were prepared. These composite films were characterized by polarized optical microscopy (POM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The POM images indicated the uniform distribution of the SCBP in the composites. The FTIR spectra indicated that the PPC structure was retained by the composite films. The XRD analysis found that the composite films had lower crystallinity than the PPC due to the presence of amorphous hemicellulose containing SCBP. A significant enhancement in thermal stability of the filler reinforced composite was noticed which was more than 30% of the PPC matrix due to the presence of polyphenols in SCBP. A maximum increase of 35% of tensile strength was observed with the addition of 20 wt% SCBP filled composite films. These biodegradable composite films with higher thermal stability and tensile strength can be considered for packaging applications. [ABSTRACT FROM AUTHOR]

This work is aimed to use polyaniline (PAni) as the conductive filler with a different weight percentage for the development of the electrical conductivity in poly (3-hydroxybutyrate) (PHB) to apply in the green electronic devices and biomedical application. PHB is brittle, and for this reason, it has mixed with polypropylene carbonate (PPC)/plasticizer (TEC) to improve its toughness and then mixed with PANI/CB to introduce semi-conductive biopolymer. I-V characteristics of the samples were measured and showed ohmic behaviors, and this is apparent as the temperature rises above 50℃. It observed the semiconductivity properties of all samples. It has been found that increasing in PANI concentration in PHB/PPC matrix leads to increase in the value of the AC conductivity, dielectric permittivity (ɛ′) and dielectric loss (ɛ″). The AC conductivity of the PHB blends is improved from 10 to 16 S cm−1 (pure PHB) to 1 S cm−1 (composite 4), and this depends on the PANI concentration. These enhance in the electrical conductivity was due to the improved miscibility between all the components as shown in DSC, the single Tg, and Tm, which was supported too by SEM where PANI/CB is good dispersion in the PHB/PPC matrix. [ABSTRACT FROM AUTHOR]

Abstract Polyester-based scaffolds have been employed in tissue engineering due to their biocompatibility, biodegradability, microstructure, and affordability. However, the acidic degradation byproducts of most common polyesters have the potential to cause inflammation and/or necrosis. In this study, we introduce a porous scaffold with benign degradation byproducts fabricated by gas-foaming based on poly(propylene carbonate) (PPC) blended with starch and bioglass particles. The pore sizes ranged from 100 to 500 μm. Manufacturing parameters were tuned from sub-critical to super-critical conditions to optimize porosity, pore size, pore interconnectivity, and mechanical properties. The biological behavior of the constructs was evaluated by in vitro toxicity and proliferation assays and in vivo subcutaneous biocompatibility. Tissue integration was observed in a joint implantation model, supporting the further development of the scaffold for tissue engineering applications. Graphical abstract Unlabelled Image Highlights • A gas foamed porous scaffold was designed based on PPC, starch and bioglass. • Subcritical and supercritical CO 2 parameters were optimized for enhanced biological performance. • In vitro and in vivo studies revealed biocompatibility and tissue infiltration in the scaffolds. [ABSTRACT FROM AUTHOR]

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To provide guidance for the practical thermal processing and applications of poly(propylene carbonate)/poly(vinyl alcohol) (PPC/PVA) blend, an environmentally friendly material with wide potential applications, thermogravimetric analysis (TG) and thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) were adopted to investigate the thermal decomposition behavior of PPC in PPC/PVA blend for its worse high-temperature thermal stability, and the decomposition processes were analyzed by Chang's method. Accordingly, the precise kinetic parameters of each thermal decomposition process were calculated by Flynn-Wall-Ozawa method. The results showed that neat PPC underwent three pyrolysis stages: unzipping, unzipping and chain random scission and unzipping. For PPC/PVA blend, the elimination reaction of the side-hydroxyl groups of PVA promoted the chain random scission of PPC, thus playing the dominant role in the thermal decomposition of PPC. The more the hydroxyl groups in PVA were, the lower the thermal stability of the blends would be. On the basis of above, a rational decomposition mechanism of PPC accelerated by PVA was proposed: With the increase in temperature, the elimination reaction of the hydroxyl groups of PVA occurred to release H+ protons; then, the H+ protons attacked the PPC backbone to release CO2 by chain random scission, leading to a rapid mass loss of PPC in PPC/PVA blend during 200-250 °C. [ABSTRACT FROM AUTHOR]

The use of magnesium alloys as degradable orthopaedic implants is limited by their rapid degradation in vivo and consequent loss of mechanical integrity before sufficient bone healing has occurred. To address this limitation, we coated the surface of AZ31 magnesium alloys with polypropylene carbonate (PPC). The obtained PPC-coated AZ31 showed reduced surface roughness, hardness, and hydrophilicity compared with bare AZ31. The PPC coating also significantly slowed the degradation of AZ31 in a simulated body fluid. The adherence and proliferation of MC3T3 osteoblastic cells cultured on PPC-coated AZ31 samples demonstrated good biocompatibility. The results of the present study indicate that application of a PPC coating may extend the functional period of AZ31 magnesium implants in vivo to allow sufficient time for bone healing and for the stimulation of new bone formation. [ABSTRACT FROM AUTHOR]

Glycidyl methacrylate (GMA) functionalized polyolefin elastomers (POE) (POE-g-GMA), which was a reactive processing agent, was melt-blended with poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) by twin-screw extrusion. The mechanical property results showed that with the addition of POE-g-GMA, the elongation at break and impact toughness of PLA/PPC blends increased while the tensile strength decreased. Dynamic thermomechanical analysis (DMA) and scanning electron microscope (SEM) results indicated that PLA/POE-g-GMA/PPC blends were partly miscible and the addition of POE-g-GMA improved the compatibility of blends. The higher Tcs and lower Tms of PLA/POE-g-GMA/PPC blends showed a depressed crystalline ability of PLA caused by the decreased chain mobility according to the differential scanning calorimetry results and the thermal stability of PLA/POE-g-GMA/PPC blends was enhanced. Rheological results revealed that the addition of POE-g-GMA made the storage modulus (G′), loss modulus (G″) and complex viscosity of the blends increase, the melt strength also improved. These findings contributed to the biodegradable materials application for designing and manufacturing PLA film. [ABSTRACT FROM AUTHOR]

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[Display omitted] • Prepared a biodegradable elastomer for electrospinning using modified PPC Polyols. • AMMT-3 has superior performance compared to current commercial products. • AMMT-3 is biodegradable and no adverse reactions when applied to the skin surface. • The research demonstrated the feasibility of industrial production of AMMT-3. The widespread use of medical tapes in healthcare settings poses challenges related to cross-contamination, incidents resulting from improper usage, and environmental pollution caused by the accumulation and disposal of medical waste. Consequently, there is an urgent need to develop a antibacterial and biodegradable medical tape. Herein, an antibacterial and biodegradable medical tape has been demonstrated to address these problems. The novel approach involves the synthesis of a series of high molecular weight polypropylene carbonate (PPC) elastomers combined with antibacterial agents like benzalkonium bromide to enhance bacterial growth resistance and prevent cross-contamination. The integration of the electrospinning technique enables the production of micro-nano fiber membranes with excellent breathability and moisture permeability. The newly developed antibacterial micro-nano medical tape (AMMT) demonstrates superior breathability (43.07 mm·s−1, 1.2 times to similar commercial products from 3 M), moisture permeability (6,589.40 g·m−2·d−1), and skin-friendliness. Furthermore, the outstanding antibacterial performance of this tape, with a 100% antibacterial rate, combined with its biodegradability, positions it as a highly promising material for applications in medical dressings and tissue engineering. [ABSTRACT FROM AUTHOR]

Applications of cyanoacrylate monomers are generally limited to adhesives/glues (instant or superglues) and forensic sciences. They tend to polymerize rapidly into rigid structures when exposed to trace amounts of moisture. Transforming cyanoacrylate monomers into transparent polymeric films or coatings can open up several new applications, as they are biocompatible, biodegradable and have surgical uses. Like other acrylics, cyanoacrylate polymers are glassy and rigid. To circumvent this, we prepared transparent cyanoacrylate films by solvent casting from a readily biodegrade solvent, cyclopentanone. To improve the ductility of the films, poly(propylene carbonate) (PPC) biopolymer was used as an additive (maximum 5 wt.%) while maintaining transparency. Additionally, ductile films were functionalized with caffeic acid (maximum 2 wt.%), with no loss of transparency while establishing highly effective double functionality, i.e., antioxidant effect and effective UV-absorbing capability. Less than 25 mg antioxidant caffeic acid release per gram film was achieved within a 24-h period, conforming to food safety regulations. Within 2 h, films achieved 100% radical inhibition levels. Films displayed zero UVC (100–280 nm) and UVB (280–315 nm), and ~15% UVA (315–400 nm) radiation transmittance comparable to advanced sunscreen materials containing ZnO nanoparticles or quantum dots. Transparent films also exhibited promising water vapor and oxygen barrier properties, outperforming low-density polyethylene (LPDE) films. Several potential applications can be envisioned such as films for fatty food preservation, biofilms for sun screening, and biomedical films for free-radical inhibition.

Abstract Poly(propylene carbonate) (PPC) nanocomposites with poly(lactic acid) (PLA) and sepiolite nanofibers (NF) double percolation networks were prepared according to the dual volume exclusions principle. A two-step melt mixing with annealing process was adopted to construct the double percolation networks, which were verified by rheological and morphological characterization. The formation of double percolation networks structure effectively increased both the mechanical properties and heat resistance of PPC due to the greatly improved efficiency of the formation of force transferring network of NF. As a result, the PPC/PLA/NF ternary nanocomposites with double percolation networks exhibited elastic modulus about three orders higher than that of the pure PPC at 100 °C. The thermal deformation temperature, evaluated from the modulus at the glass transition of pure PPC (0.1 GPa), was found to be above 100 °C. [ABSTRACT FROM AUTHOR]

The ambient temperature application of solid-state batteries (SSBs) based on ceramic/PEO composite solid electrolyte has been restrained by the poor ionic conductivity of PEO-based polymer. Herein, we have studied high-salt-concentrated polymeric electrolyte comprising poly(propylene carbonate) (PPC) and lithium bis-(fluorosulfonyl) imide (LiFSI), as well as its application in ceramic/polymer composite solid electrolytes based SSBs. The PPC-LiFSI 80 wt.% electrolyte showed a significantly improved ionic conductivity on the order of 10 −4  S cm −1 at ambient temperature, Li transference number of 0.75, and anodic stability up to 4.5 V versus Li/Li + . The LiFePO 4 /Li cell with Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP)/PPC-LiFSI 80 wt.% composite electrolyte showed stable charge/discharge profiles and excellent cycling performance, which delivered a specific discharge capacity of 138.3 mAh g −1  at 0.1C and a high capacity retention of 97.1% after 100 cycles. According to EIS results, we found that the reduced cell deterioration and polarization is attributed to the improved interface between the electrode and the solid electrolyte, which is realized by introducing the flexible and conductive high-salt-concentrated polymeric electrolyte PPC-LiFSI 80 wt.%. The results indicate that ceramic/high-salt-concentrated PPC-based polymer composite electrolyte is promising for ambient temperature solid-state lithium batteries. [ABSTRACT FROM AUTHOR]

Improving glass transition temperature (T g ) and mechanical property of the environment-friendly poly(propylene carbonate) via intermacromolecular complexation through hydrogen bonding is attractive and of great importance. A novel and effective strategy to prepare (polypropylene carbonate/nanocrystalline cellulose)/polyvinyl alcohol ((PPC/NCC)/PVA) composites with inner-outer double constrained structure was reported in this work. Outside the PPC phase, PVA, as a strong skeleton at microscale, could constrain the movement of PPC molecular chains by forming hydrogen bonding with PPC at the interface of PPC and PVA phases; inside the PPC phase, the rod-like NCC could restrain the flexible molecular chains of PPC at nanoscale by forming multi-hydrogen bonding with PPC. Under the synergistic effect of this novel inner-outer double constrained structure, T g , mechanical properties and thermal stability of (PPC/NCC)/PVA composite were significantly increased, e.g. T g of the composite researched the maximum value of 49.6 °C, respectively 15.6 °C, 5.7 °C and 4.2 °C higher than that of PPC, PPC/NCC and PPC/PVA composite. [ABSTRACT FROM AUTHOR]

In this paper, the black liquor lignin (BL) from pulp and paper industry was chemically modified using formaldehyde to adjust its aggregation structure and dispersion behavior. The properties of the formaldehyde-modified black liquor lignin (BLF) were measured by Fourier transform infrared spectroscopy, transmission electron microscopy, and differential scanning calorimetry. Results indicated that the BLF had better dispersion ability than BL. Therefore, the BLF as reinforcing fillers was incorporated into poly(propylene carbonate) (PPC) by melt compounding to prepare biodegradable BLF/PPC composites. The tensile properties, microstructure, thermal decomposition properties, and rheological properties of the BLF/PPC composites were investigated. Results showed that the performance of composites was depend on the dispersion of BLF. After adding a small amount of BLF into PPC, the tensile strength, tensile modulus, thermal stability, and processing stability of the composite were significantly improved. [ABSTRACT FROM AUTHOR]

Flexible interfaces between Si anodes and composite electrolytes consisting of poly(propylene carbonates) (PPCs) and garnets have been fabricated. The solid polymer electrolytes (SPEs) of PPC/garnet/LiTFSI show the conductivity of 4.2 × 10 −4  S cm −1 at room temperature. Their combination with the Si layer anodes allows great alleviation of internal stress resulting from the large volume variation during lithiation and delithiation process of Si anodes. As a result, the Si/SPE/Li cells exhibit 2520 mAh g −1 , 2260 mAh g −1 , 1902 mAh g −1 , 1342 mAh g −1 at 0.1 C, 0.2 C, 0.5 C, and 1 C, respectively. Furthermore, with such compatible and stable interfaces of Si/SPE and the LiFePO 4 cathodes in solid-state batteries, the specific capacity of 2296 mAh g −1 in terms of Si is obtained, which remains 82.6% after 100 cycles at room temperature and 0.1 C. The results here indicate that constructing of flexible interfaces between Si anodes and SPEs is a promising strategy to develop high performance solid-state batteries. [ABSTRACT FROM AUTHOR]

The inherent variability and insufficiencies in the co-production of propylene from steam crackers has raised concerns regarding the global propylene production gap and has directed industry to develop more on-purpose propylene technologies. The oxidative dehydrogenation of propane by CO2 (CO2-ODHP) can potentially fill this gap while consuming a greenhouse gas. Non-precious FeNi and precious NiPt catalysts supported on CeO2 have been identified as promising catalysts for CO2-ODHP and dry reforming, respectively, in flow reactor studies conducted at 823 K. In-situ X-ray absorption spectroscopy measurements revealed the oxidation states of metals under reaction conditions and density functional theory calculations were utilized to identify the most favorable reaction pathways over the two types of catalysts. [ABSTRACT FROM AUTHOR]

Potato starch modified with varying hydrolysis time and propylene oxide content was prepared to investigate the structure and rheological properties of acid-hydrolyzed-hydroxypropylated potato starch (AHP). The preceding acid hydrolysis, which altered the surface and interior properties of the starch granules, led to increased degree of hydroxypropylation. Pronounced differences in structural characteristics of starch were observed with changing hydrolysis time. Any increase in the hydrolysis time or propylene oxide content resulted in an increase in the flow behavior index and a decrease in consistency coefficient of the dual-modified starch. The gelling and gel properties appeared to be governed by the characteristics of starch molecules, i.e., samples with medium molecular weight and a relatively low degree of hydroxypropyl substitution were characterized by superior gelling ability and gel strength. The relationship between the properties of the sol-gel transition and the degree of the dual modification was further confirmed by examining the starch microstructure and changes in water distribution. The current study provides basic knowledge required for the use of AHP in such useful applications, as coating, encapsulation and hydrogel formation, in the food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Abstract: Two cobalt(II) oxaporphyrins (OTPPCoCl and OTPPCoSbF6) are synthesized in this work and are characterized, including by X‐ray crystallography. Both complexes are tested as catalysts in the copolymerization of propylene oxide (PO)/cyclohexene oxide (CHO) and CO2. Polycarbonate is obtained in CHO/CO2 copolymerization with OTPPCoCl as a catalyst, whereas in the case of PO, cyclic carbonate (CC) is majorly formed. An anion exchange from Cl− to SbF6− of the cobalt(II) oxaporphyrin leads to a drastic change in the product selectivity: sole polyether is afforded for both epoxides. The polyether formation by OTPPCoSbF6 is postulated to proceed via a cationic mechanism. Further, an equivalent admixture of OTPPCoCl and OTPPCoSbF6 allows the formation of poly(propylene carbonate). In this copolymerization, the latter catalyst acts as a PO activator, while OTPPCoCl functions as the initiator. In addition, density functional theory (DFT) calculations reveal a lower ring‐opening energy of PO by OTPPCoSbF6, compared with the usual propagating species, OTPPCo‐alkoxides and OTPPCo‐carbonates. [ABSTRACT FROM AUTHOR]

ABSTRACT The in situ formation of poly(lactic acid)- b-poly(propylene carbonate) (PLA- b-PPC) block copolymers were carried out by the reaction between PLA and PPC in the presence of tetrabutyl titanate via transesterification. Molecular weight measurements and 13C nuclear magnetic resonance spectroscopy revealed that PLA- b-PPC block copolymers with higher molecular weight were obtained by controlling the reactivity point ratio between PLA chains and PPC chains in PLA/PPC reaction system. The sample with a composition of PLA:PPC = 40:60 (wt %) and a catalyst amount of 0.5 wt % had a more proportionable reactivity point ratio between PLA chains and PPC chains compared with other samples, resulting in a most conspicuous transesterification and inconspicuous chain scission reaction. Therefore, its high molecular weight fraction ( Mw > 40.0 × 104) increased 80%. The formation of macromolecular PLA- b-PPC copolymer could strengthen the entanglement between PLA and PPC molecular chains, which resulted in an increased viscosity of blends at low shear rate. In addition, the elongation at break of sample with a composition of PLA:PPC = 40:60 (wt %) and a catalyst amount of 0.5 wt % was nearly as twice as which without catalyst because of the improving miscibility of PLA domains and PPC matrix by the compatibilization of PLA- b-PPC copolymer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46009. [ABSTRACT FROM AUTHOR]

ABSTRACT Poly(propylene carbonate) (PPC) is a promising new sustainable polymer produced from carbon dioxide. PPC has inferior thermal stability which could be enhanced by synergistic blending with other polymers. Blends of PPC and the engineering thermoplastic polyoxymethylene are produced by melt compounding in various weight ratios. The compatibility of the blends is investigated using thermogravimetric analysis (TGA), differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), density measurements, and scanning electron microscopy (SEM). TGA reveals that thermal stability of the blends increases dramatically in comparison to the neat PPC. A small shift in the glass transition temperature demonstrates the immiscibility of the blends but also indicates some compatibility, attributed to potential dipole-dipole interactions which are also corroborated with the FTIR results. A deviation of the rule of mixtures for density is found for some of the blends. SEM analysis of the blends shows two phase morphology; however, the interfacial adhesion appeared to be enhanced with increasing PPC content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45823. [ABSTRACT FROM AUTHOR]

Tens of billion metric tons of anthropogenic CO discharged from the burning of fossil fuels lead to an enormous environmental and resource burden. It is charming to transform CO to desirable, economical chemicals and materials. Poly(propylene carbonate) (PPC) is an emerging CO-based material. Herein, we report the design, synthesis and characterization of the reactive hot melt polyurethane adhesive (RHMPA) based on PPC polyol. The resultant RHMPAs exhibit good adhesion properties to multiple substrates including plastics (PC, PMMA, ABS) and metals (aluminium, steel), which is comparable to or even better than conventional RHMPAs prepared from petro-based polyol. Furthermore, the PPC-based RHMPAs have tunable mechanical properties, and are thermally stable in the typical working range of bonding process (up to 270 °C). The study is expected to expand the applications of PPC and provide a new type of CO-based renewable and eco-friendly materials. [ABSTRACT FROM AUTHOR]

An ionic/nonionic polyurethane dispersion with high solid content and low viscosity with a complex hydrophilic chain-extending agent was prepared using isophorone diisocyanate as a hard segment and propylene oxide glycol as a soft segment. The complex hydrophilic chain-extending agent consisted of DPSA and BDSA. The effects of the molar ratio of DPSA/BDSA on the properties of the resultant polyurethane dispersions were studied. The morphologies and properties of the ionic/nonionic PU dispersions were examined using particle-size, TEM, and viscosity analyses. It was found that the ionic/nonionic dispersions possessed wide particle-size distributions due to the addition of the complex hydrophilic chain-extending agent. The ionic/nonionic PU dispersions possessed higher solid content than conventional WPU dispersions because the number and volume percentage of the large particles and small particles of the ionic/nonionic dispersions met the requirements for high solid content. It was observed that the solid content of the ionic/nonionic dispersion increased and then decreased with an increasing molar ratio of DPSA/BDSA. When the ratio ranged from 4:10 to 5:10, the solid content of the ionic/nonionic PU dispersion reached up to 55%. It was also noticed that the apparent viscosity of the ionic/nonionic polyurethane dispersion decreased with an increasing molar ratio of DPSA/BDSA. The complex hydrophilic chain-extending agent consisting of DPSA and BDSA enhanced the solid content and decreased the viscosity of the ionic/nonionic dispersions, which are very important for improving the properties and expanding the applications of PU dispersions. In addition, the ionic/nonionic polyurethane dispersion had good electrolyte-resistance properties, stability at both high and low temperatures, and storage stability. [ABSTRACT FROM AUTHOR]

An efficient processing modifier silica-g-poly(lactic acid)/poly(propylene carbonate) (SiO2-g-PLA/PPC) was synthesized by grafting reaction and poly(lactic acid)/poly(propylene carbonate) (PLA/PPC) nanocomposites were prepared using a Haake torque rheometer. Fourier transforms infrared (FTIR) spectrometry, 1H nuclear magnetic resonance (1H NMR), thermogravimetric analysis (TGA), and rheological results showed together that the PLA and PPC molecular chains were successfully grafted on the surface of nanosilica (nano-SiO2). The scanning electron microscopy (SEM) photographs showed that SiO2-g-PLA/PPC could effectively improve the interface adhesion of PLA/PPC blends, so that the compatibility of the two improved. Moreover, SiO2-g-PLA/PPC could effectively toughen PLA/PPC blends, accelerate crystallization and increase the relaxation time of PLA/PPC blends which leads to an improvement of processing performance effectively. All of the above improvements of PLA/PPC nanocomposites were attributed to the strong entanglements between polymer chains grafted on the nano-SiO2 and the polymer matrix. [ABSTRACT FROM AUTHOR]

Intercalated nanocomposites comprised of poly(propylene carbonate) (PPC) and organo-montmorillonite (OMMT) were prepared via a direct melt blending method. The morphological, thermal, rheological, mechanical, and gas barrier properties of composites were carried out in detail. Results of XRD, TEM, and SEM revealed that OMMT dispersed homogeneously in the polymer matrix, and were intercalated by PPC macromolecules. Compared with neat PPC, the PPC/OMMT nanocomposites showed an enhancement in the 5 wt% weight loss temperature ( T ) by near 20 °C with 3 phr OMMT concentration. With the percolation threshold formed, the rheological properties of composites translated from a liquid-like behavior to a solid-like one. Interestingly, PPC/OMMT nanocomposites revealed a concurrent improvement in the modulus, yield strength, and toughness with the addition of homogeneously dispersed clay. The oxygen permeability of well-dispersed PPC/OMMT nanocomposites reduced significantly compared with that of neat PPC. Consequently, this convenient and effective method, which facilitates to prepare PPC/OMMT nanocomposites with superior mechanical properties and excellent gas barrier performances, can be considered to broaden the application of PPC. [ABSTRACT FROM AUTHOR]