Preparation and properties of poly(propylene carbonate) and nanosized ZnO composite films for packaging applications

A series of polypropylene carbonate (PPC)/ZnO nanocomposite films with different ZnO contents were prepared via a solution blending method. The morphological structures, thermal properties, oxygen permeability, water sorption, and antibacterial properties of the films were investigated as a function of ZnO concentration. While all of the composite films with less than 5 wt % ZnO exhibited good dispersion of ZnO in the PPC matrix, FTIR and SEM results revealed that solution blending did not lead to a strong interaction between PPC and unmodified ZnO. As such, poor dispersion was induced in the composite films with a high ZnO content. By incorporating inorganic ZnO filler nanoparticles, the diffusion coefficient, water uptake in equilibrium, and oxygen permeability decreased as the content of ZnO increased. The PPC/ZnO nanocomposite films also displayed a good inhibitory effect on the growth of bacteria in the antimicrobial analysis. The enhancement in the physical properties achieved by incorporating ZnO is advantageous in packaging applications, where antimicrobial and environmental‐friendly properties, as well as good water and oxygen barrier characteristics are required. Furthermore, UV light below ～ 350 nm can be efficiently absorbed by incorporating ZnO nanoparticles into a PPC matrix. ZnO nanoparticles can also improve the weatherability of a PPC film. In future research, the compatibility and dispersion of the PPC matrix polymer and the inorganic ZnO filler nanoparticles should be increased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Poly(propylene carbonate)/aluminum flake composite films with enhanced gas barrier properties

A series of poly(propylene carbonate) (PPC)/aluminum flake (ALF) composite films with different ALF contents were prepared via a melt‐blending method. Their cross‐section morphologies, thermal properties, tensile strength (TS), and gas barrier properties were investigated as a function of ALF contents. SEM images reveal the good dispersion and orientation of ALF along with melt flow direction within PPC matrix. The oxygen permeability coefficient (OP) and water vapor permeability coefficient (WVP) of the composite films decrease continuously with ALF contents increasing up to 5 wt %, which are 32.4% and 75.2% that of pure PPC, respectively. Furthermore, the TS and thermal properties of PPC/ALF composite film are also improved by the incorporation of ALF particles. The PPC/ALF composite films have potential applications in packaging area due to its environmental‐friendly properties, superior water vapor, and oxygen barrier characteristics. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41663.     

Thermal and barrier properties of EVOH/EFG nanocomposite films for packaging applications: Effect of the mixing method

Ethylene‐vinyl alcohol copolymer (EVOH)/exfoliated graphite (EFG) nanocomposite films were prepared by precoating EFG on the EVOH surface and conducting a successive melt‐extrusion process. Their physical properties were strongly dependent on the EFG content and the mixing method, which strongly affected the morphology and surface properties of the nanocomposite films. The hydrophobicity and water resistance property of EVOH increased by incorporating hydrophobic EFG and their effects were more pronounced in the precoating method, which is related to good dispersion of EFG in EVOH and an enhanced crystalline structure. The incorporation of EFG into EVOH by the precoating method more effectively diminished the dependence of the relative humidity on the oxygen transmission rate of pure EVOH and increased the oxygen barrier properties of EVOH at a high relative humidity. The incorporation of EFG into EVOH by the precoating method also induced relatively more enhanced thermal stability. These results suggest the feasibility of the application of moisture‐sensitive EVOH resin for food packaging films. POLYM. COMPOS., 37:1744–1753, 2016. © 2014 Society of Plastics Engineers     

Biodegradable PPC/(PVA-TPU) ternary blend blown films with enhanced mechanical properties

Biodegradable films of poly(propylene carbonate)/poly(vinyl alcohol)-thermoplastic polyurethane [PPC/(PVA-TPU)] ternary blends were successfully prepared by melting blending method. The mechanical properties of poly(propylene carbonate) blown film were greatly improved by blending PPC with PVA-TPU. In order to afford the melt processing of PVA, the PVA-TPU binary blend was firstly prepared using thermoplastic polyurethane as a polymeric plasticizer. The rheological behavior, mechanical properties and morphology of these blends were studied. Considering its melt viscosity and thermally processing temperature, the PVA-50%TPU, as a modifier, was blended with PPC to prepare PPC/(PVA-TPU) ternary blend. SEM observation revealed a basic one-phase morphological structure with very good interfacial adhesion between the extremely blurred PPC and PVA-TPU two components. Meanwhile, the miscibility of the ternary components was verified by only one glass-transition temperature obtained from DMA tests. The tensile strength and tear strength of PPC/(PVA-TPU) blown films were determined at different temperatures. The results demonstrate that the mechanical properties of PPC/(PVA-TPU) films were enhanced dramatically at low temperature when compared with neat PPC. At room temperature, PPC/30 %(PVA-50%TPU) blown film exhibited a tensile strength of 26 MPa, and an elongation at break of 484.0 %. Its tear strength in the take-up direction is 124.1 kN/m, and the one in machine direction is 141.9 kN/m. At a low temperature of 0 °C, PPC/30 %(PVA-50%TPU) exhibited a tensile strength of 40.7 MPa and tear strength of 107 kN/m, which are 153 % and 142 % of those of neat PPC respectively. The blending of PPC with the PVA plasticized with TPU provides a practical way to extend the application of the new biodegradable polymer of PPC in the area of blown films.     

Improving the thermal and mechanical properties of poly(propylene carbonate) by incorporating functionalized graphite oxide

Poly(propylene carbonate) (PPC) is a new biodegradable aliphatic polycarbonate. However, the poor thermal stability, low glass transition temperatures (T_g), and relatively low mechanical property have limited its applications. To improve the thermal and mechanical properties of PPC, functionalized graphite oxide (MGO) was synthesized and mixed with PPC by a solution intercalation method to produce MGO/PPC composites. A uniform structure of MGO/PPC composites was confirmed by X‐ray diffraction and scanning electron microscope. The thermal and mechanical properties of MGO/PPC composites were investigated by thermal gravimetric analysis, differential scanning calorimetric, dynamic mechanical analysis, and electronic tensile tester. Due to the nanometer‐sized dispersion of layered graphite in polymer matrix, MGO/PPC composites exhibit improved thermal and mechanical properties than pure PPC. When the MGO content is 3.0 wt %, the MGO/PPC composites shows the best thermal and mechanical properties. These results indicate that nanocomposition is an efficient and convenient method to improve the properties of PPC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

EVOH nanocomposite films with enhanced barrier properties under high humidity conditions

To improve the oxygen and water vapor barrier properties of ethylene vinyl alcohol, EVOH/EFG nanocomposite films under high humidity conditions, we successfully prepared highly exfoliated graphite (EFG) containing a monolayer or a few layers of graphene via rapid heating treatment and ultrasonication as confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), elemental analysis (EA), and nitrogen adsorption–desorption analysis. Six different EVOH/EFG nanocomposite films containing as‐prepared EFG were prepared via a solvent blend method and their physical and barrier properties at different relative humidities were investigated as a function of EFG content. Depending on the EFG content, oxygen transmission rate (OTR) decreased from 3.7 to 0.1 cc/m²/day at dry condition, and the difference in OTR between dry condition and humid condition decreased from 6.5 to 2.3 cc/m²/day. Barrier properties of the EVOH/EFG nanocomposite films were strongly dependent on their chemical structure and morphology. Crystallinity, tortuous path length, and hydrophobicity of EVOH/EFG nanocomposite films were enhanced by the addition of EFG. However, the thermal stability and glass transition temperature of the nanocomposite films were not improved by incorporation of EFG due to the weak interaction between EVOH and EFG. To maximize the performance of EVOH/EFG nanocomposite films, the compatibility of the polymer matrix and fillers needs to be improved. POLYM. COMPOS., 35:644–654, 2014. © 2013 Society of Plastics Engineers     

Study on nitrile-butadiene rubber/poly(propylene carbonate) elastomer as coupling agent of poly (vinyl chloride)/poly (propylene carbonate) blends. I. Effect on mechanical properties of blends

Nitrile-butadiene rubber/poly(propylene carbonate) (NBR-PPC) elastomer was studied as a coupling agent of the blends of poly(vinyl chloride) (PVC) with poly(propylene carbonate) (PPC). It greatly improved the PVC/PPC system mechanical properties that were dependent on the amount and composition of the coupling agent. When the coupling agent consisted of a 70/30 ratio of NBR/PPC (in which NBR had 34% nitrile content) and 2.5 phr of benzoyl peroxide (BPO) initiator and underwent a prevulcanization, the blends of PVC/PPC displayed excellent mechanical properties by adding 8 phr of the coupling agent. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1107–1111, 1997     

碳酸钙改性聚碳酸亚丙酯研究

利用双螺杆挤出机研究了分别填充不同表面改性的碳酸钙后对聚碳酸亚丙酯片材专用料(PPC101)性能的影响。结果表明:随着碳酸钙(CaCO3)用量的增加,试样的维卡软化温度皆呈上升趋势,未进行表面处理的碳酸钙填料对PPC101维卡软化温度的提高更明显;填料是否进行表面处理对PPC101材料的拉伸性能影响不大,随着填料用量的增加,未进行表面处理和硬脂酸处理的碳酸钙填充PPC101材料的拉伸强度均呈先上升后基本稳定的趋势,而使用铝酸酯的碳酸钙填充PPC101材料的拉伸强度几乎不变;随着填料用量的增加,无论填料是否进行表面改性,试样的冲击强度和熔体质量流动速率均呈下降趋势;而且密度均呈线性上升趋势。     

PPC/PDAP共混膜的制备和性能

将过氧化二异丙苯(DCP)置于特定温度下,引发邻苯二甲酸二烯丙酯(DAP)在聚碳酸亚丙酯(PPC)溶液中聚合,制备得到聚碳酸亚丙酯/聚邻苯二甲酸二烯丙酯(PPC/PDAP)共混膜。采用红外光谱仪(FTIR)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)、热重分析仪(TGA)、万能试验机和水蒸气透过率测试仪对共混膜的红外吸收、结晶性、热、力学和阻隔性能进行了表征。结果表明,通过DAP的聚合,提高了PPC的结晶性,使PDAP在PPC基体中形成交联网络,提高了共混膜的热、力学和阻隔性能。相比纯PPC,当DAP含量为20%时,共混膜的玻璃化转变温度和拉伸强度分别提高了5.3℃和266%;当DAP含量为40%时,共混膜的失重5%热分解温度提高了50.9℃,透湿系数下降了25%,因此,阻隔性能得到了提升。     

Improved thermal stability and mechanical properties of poly(propylene carbonate) by reactive blending with maleic anhydride

To extend the application of a carbon dioxide sourced environmental friendly polymer: poly (propylene carbonate) (PPC), a small amount of maleic anhydride (MA) was melt blended to end‐cap with PPC to improve its thermal stability and mechanical properties. Thermal and mechanical properties of end‐capped PPC were investigated by TGA, GPC, mechanical test, and DMA. TGA and titration results demonstrate that PPC can be easily end‐capped with MA through simple melt blending. TGA results show that the thermal degradation temperature of PPC could be improved by around 140°C by adding MA. GPC measurement indicates that the molecular weight of PPC can be maintained after blending with MA, where pure PPC experiences a dramatic degradation in molecular weight during melt process. More importantly, the tensile strength of PPC after blending with MA was found to be nearly eight times higher than that of pure PPC. It has approached the mechanical properties of polyolefin polymers, indicating the possibility of replacing polyolefin polymers with PPC for low temperature applications. The method described here could be used to extend the applications of PPC and fight against the well known global warming problem. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Orientation microstructure and properties of poly(propylene carbonate)/poly(butylene succinate) blend films

The blends of high molecular weight poly(propylene carbonate) (PPC) and poly(butylene succinate) (PBS) were melt blended using triphenylmethane triisocyanate (TTI) as a reactive coupling agent. TTI also serves as a compatibilizer for the blends of PPC and PBS. The blend containing 0.36 wt % TTI showed that the optimal mechanical properties were, therefore, calendared into films with different degrees of orientation. The calendering condition, degree of orientation, morphologies, mechanical properties, crystallization, and thermal behaviors of the films were investigated using wide‐angle X‐ray diffraction, scanning electron microscopy, tensile testing, and differential scanning calorimetry (DSC) techniques. The result showed that the as‐made films exhibited obvious orientation in machine direction (MD). Both tensile strength in MD and the tear strength in transverse direction (TD) increased with increasing the degree of orientation. The orientation of the film also increased the crystallinity and improved the thermal properties of the PPC/PBS blend films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Improved mechanical properties,barrier properties and degradation behavior of poly(butylenes adipate-co-terephthalate)/poly(propylene carbonate) films

Poly(butylene adipate-co-terephthalate) (PBAT) was blended with poly(propylene carbonate) (PPC) by a twin screw extruder and then the blends were made onto films via the blown film technique. PPC dispersed uniformly in the PBAT matrix, and the glass transition temperature (T _g ) of PBAT were decreased with the increasing content of PPC. Wide angle X-ray diffraction confirmed that the crystallite dimension of PBAT was decreased after blending PBAT with the amorphous PPC. The results of mechanical tests indicated that the PBAT/PPC films showed high tensile strength and tear strength. In addition, the PBAT/PPC films showed high carbon dioxide permeability and moderate oxygen and nitrogen permeability. After embedding in soil, the weight loss and mechanical properties analysis demonstrated that the films were remarkably biodegraded. These findings contributed to application of the biodegradable materials, such as design and manufacture polymer packaging.     

PBAT/PPC多层共挤薄膜的制备及其阻透性能研究

以聚碳酸亚丙酯(PPC)和聚对苯二甲酸己二酸丁二醇酯(PBAT)为原料,采用多层共挤吹塑的方法制备了全生物降解高阻透性3层复合薄膜PBAT/PPC/PBAT。讨论了PPC层厚度、PBAT层厚度及在一定挤出量时,薄膜牵引速度对复合薄膜性能的影响。结果表明,与纯PPC薄膜相比,PBAT/PPC/PBAT复合薄膜的拉伸强度和加工性能得到提高,其拉伸强度最大提高了200 %;薄膜厚度和分子链的取向度对阻透性有较大影响,当PPC层厚度最大（约为12 μm）时,氧气透过率最小,为9.5×10^-15 cm3·cm/(cm2·s·Pa）;牵引速度最大,即分子链取向度最大时,氧气透过率最小,为9.52×10^-15 cm3·cm/(cm2·s·Pa）。     

Morphology, thermal stability and rheology of poly(propylene carbonate)/organoclay nanocomposites with different pillaring agents

Unpillared montmorillonite PGV and five organoclays (Nanocor's Nanomer I.44P, I.24TL and I.34TCN and Southern Clay Product's C25A and C30B) were high shear melt-blended (2.5 wt%) into poly(propylene carbonate) (PPC). Solubility parameters of the clay pillaring agents versus that of PPC were used to predict clay/PPC miscibilities and these were compared to XRD and TEM nanoclay dispersion measurements. Clays I.34TCN and C30B, with the highest predicted pillaring agent/PPC miscibilites, had partially exfoliated morphologies. Clays I.24TL, C25A and I.44P, with pillaring agents predicted to be less PPC miscible, were less highly nanodispersed. Quaternary ammonium pillars with two 2-hydroxyethyl groups promoted the best nanodispersion in PPC. 12-Aminododecanoic acid (in I.24TL) promoted the intercalation. Dimethyl dialkyl quaternary ammoniums (in I.44P and C25A) were less effective. Organoclay dispersion improved the thermal stability. The PPC/I.24TL nanocomposite, with the most stable 12-aminododecanoic acid pillar, was the most thermally stable (PPC/I.34TCN and PPC/C30B were the second and third). The nanocomposites exhibited narrower linear viscoelastic zones than PPC and solid-like behaviors in these linear zones.     

Partially miscible poly(lactic acid)‐ blend‐poly(propylene carbonate) filled with carbon black as conductive polymer composite

BACKGROUND: Conductive polymer composites (CPCs) can be obtained by filling polymer matrices with electrically conductive particles, and have a wide variety of potential applications. In the work reported, the biodegradable polymer poly(lactic acid) (PLA) as a partially miscible blend with poly(propylene carbonate) (PPC) was used as a polymer matrix. Carbon black (CB) was used as the conducting filler. RESULTS: Fourier transform infrared spectroscopy revealed interactions between matrix and CB filler; this interaction was stronger in PPC‐blend‐CB than in PLA‐blend‐CB composites. A rheology study showed that low‐viscosity PPC could improve the fluidity of the CPCs, but decrease that of CB. With increasing CB content, the enforcement effect, storage modulus and glass transition temperature increased, but the elongation at break decreased. CPCs exhibited the lowest electrical percolation thresholds of 1.39 vol.% CB when the content of PPC in PLA‐blend‐PPC was 40 wt%. The conductivity of CPCs containing 5.33 vol.% CB and 40 wt% PPC reached 1.57 S cm^?1. Scanning electron microscopy revealed that CB exhibits a preference for dispersion in the low‐viscosity phase (PPC) of the multiphase matrix. CONCLUSION: In the presence of CB, partially miscible PLA‐blend‐PPC could form multi‐percolation CPCs. Moreover, the combination of PLA and PPC with CB broadens novel application of both renewable polymers and CPCs. Copyright © 2008 Society of Chemical Industry     

Inhibitory effect of hydrogen bonding on thermal decomposition of the nanocrystalline cellulose/poly(propylene carbonate) nanocomposite

Biodegradable poly(propylene carbonate, PPC) is a typical noncrystalline polymer from the copolymerization of carbon dioxide (CO₂) with propylene oxide (PO). But it is easy to be degraded to propylene carbonate (PC) via backbiting route during heat process (above 170°C), which limits its application. This work reports the introduction of biodegradable nanocrystalline cellulose (NCC) which was exfoliated from microcrystalline cellulose (MCC) by acid hydrolysis into PPC, affording a biodegradable PPC/NCC nanocomposite with improved thermal decomposition temperatures (the initial decomposition temperature, T_5wt% was up to 265°C). Impressively, the thermal decomposition of PPC to PC at 200°C within 4.0 h was dramatically inhibited by introducing NCC, which was evident by ¹H NMR spectra. This could be attributed to the hydrogen bonding interaction between NCC and PPC. Moreover, the film of PPC/NCC nanocomposite had not deformed when it was heated at 110°C for 4 h. In application, such biodegradable nanocomposite is a promising disposable package material. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39847.     

超支化乙二胺三嗪聚合物对PPC/PBS共混体系的增强改性研究

以超支化乙二胺三嗪聚合物（HBETP）为改性剂,采用熔融共混法制备了聚碳酸亚丙酯（PPC）/聚丁二酸丁二醇酯（PBS）/HBETP共混物;利用动态热机械分析仪、热失重分析仪、电子万能试验机、旋转流变仪、扫描电子显微镜等,对其热性能、力学性能、流变性能、断面形貌等进行了表征。结果表明,当HBETP含量为0.5 %（质量分数,下同） 时,PPC/PBS/HBETP共混物在韧性基本保持不变的情况下,拉伸强度提高幅度最大,由7.56 MPa提高到11.22 MPa,增幅为49.6 %;HBETP的加入可以提高PPC/PBS的相容性,且适当的含量会使PPC/PBS的拉伸强度提升。     

Fabrication and characterization of biodegradable poly(propylene carbonate)/wood flour composites

Wood flour reinforced poly(propylene carbonate) (PPC) composites were prepared by melt blending followed by compression molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, and thermal properties of PPC/wood flour composites were investigated. In terms of mechanical properties, wood flour had the significant effect of improving tensile strength and stiffness. Scanning electron microscopic examination revealed good dispersion of wood flour (especially at lower content) in the PPC matrix. Moreover, experimental results indicated that the wood flour addition led to an obvious improvement in the thermal stability of the composites. This paper demonstrates that the incorporation of low‐cost and biodegradable wood flour into PPC provides a practical way to produce completely biodegradable and cost‐competitive composites with good mechanical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 782–787, 2006     

Effect of chain extrender on the compatibility,mechanical and gas barrier properties of poly(butylene adipate-co-terephthalate)/poly(propylene carbonate) bio-composites

Bio-composites consisting of poly(butylene adipate-co-terephthalate) (PBAT), poly(propylene carbonate) (PPC) and epoxy chain extender ADR 4468 were fabricated via melt blending using a torque rheometer. The relationship of the torque, melt viscosity, and molecular weight of the bio-composites was established via polymeric liquid theory to estimate the real-time chain extension reaction rate under different ADR contents. At the meantime, rheological behavior, thermal and mechanical properties, morphologies, gas barrier properties of the PBAT/PPC/ADR bio-composites were systematically characterized. The corresponding results revealed that the water vapor transmission rate (WVTR) reduced by 50% under 30 phr (parts per hundreds of resin) PPC content. The addition of ADR is beneficial to improve the mechanical properties, thermal stability and phase dispersion of PBAT/PPC without affecting the water barrier property. With 3 phr ADR, the tensile stress and elongation at break were increased from 19.5 MPa and 1184% to 26.9 MPa and 1443%, respectively. In addition, the data of the torque rheometer revealed that the chain extension reaction rate and the melt viscosity was increased with the increasing ADR content, but the reaction rate was reduced with the excessive viscosity.     

Chain extension and modification of polypropylene carbonate using diphenylmethane diisocyanate

In the present work, with the application of diphenylmethane diisocyanate (MDI) as the chain extender, poly(propylene carbonate) (PPC) was modified by chain extension. The changes in the chemical, thermal and mechanical properties of PPC after modification were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetry and elemental analysis. The experimental results indicate that during melt blending of MDI and PPC the terminal hydroxyl group in PPC can react with the isocyanate group in MDI, leading to chain extension of PPC. Via modification, the physical properties and thermal stability of PPC can be enhanced considerably. With the addition of 1.5% MDI, the glass transition temperature increased from 14.1 °C to 28.2 °C and the thermal decomposition temperature T_?5% increased from 162.7 °C to 246.8 °C. Moreover, the tensile strength of the modified PPC was improved from 3.1 MPa to 20.3 MPa. © 2015 Society of Chemical Industry