Co-reporter:Guo Jiang, Mengdi Zhang, Jian Feng, Shuidong Zhang, and Xiaohui Wang
ACS Sustainable Chemistry & Engineering December 4, 2017 Volume 5(Issue 12) pp:11246-11246
Publication Date(Web):October 26, 2017
DOI:10.1021/acssuschemeng.7b01674
Bionanocomposites of poly(propylene carbonate) (PPC) enhanced by cellulose nanocrytals (CNCs) are prepared via a two-step process using polyethylene glycol (PEG) as a carrier. Interfacial interaction among PPC, PEG, and CNCs, dispersion of CNCs in bionanocomposites, thermal properties, mechanical behavior, oxygen barrier property, and rheological responses are investigated. The obtained PPC/PEG/CNC nanocomposites display obvious improvement of barrier properties by adding an extremely low loading of CNCs. O2 permeability is decreased by more than 76% at CNC loading of 0.3 wt %. The Cussler model works better to predict gas barrier for nanocomposites. TEM results show that CNC is well dispersed in the matrix, and the introduction of CNC remarkably increases the tensile strength and storage modulus of PPC. Interestingly, elongation at break of the PPC/PEG/CNC nanocomposite remains above 580%. Moreover, the inclusion of CNCs increases the thermal stability and initial decomposition temperature (T–5%) of nanocomposites. The T–5% for the PPC/PEG/0.7CNC nanocomposite is approximately 246.5 °C, which is increased by 17.1% compared with that of pure PPC (210.5 °C). This makes PPC/PEG/CNC nanocomposites a very promising degradable material for food packaging applications.Keywords: Cellulose nanocrytals; Cussler model; Gas barrier; Poly(propylene carbonate); Polyethylene glycol;
Co-reporter:Shuidong Zhang;Lingcao Tan;Huaqiao Peng;Jizhao Liang;Guo Jiang
Polymer Composites 2016 Volume 37( Issue 2) pp:370-378
Publication Date(Web):
DOI:10.1002/pc.23189
In this work, when glass fiber reinforced liquid crystalline polymer (GFLCP) was subjected to injection molding once, the recycled GFLCP (RGFLCP) including the scraps and unqualified injection products was granulated by different extruders with varying screw configurations. The glass fibers were observed by SEM and their lengths were calculated by mathematical statistics. In the case of the samples prepared by a single-screw extruder, the average glass fiber length ( ) and the percentage of glass fibers whose length was higher than critical length (Vj) gradually decreased with the increase of the screw diameter and the ratio of its length to diameter (L/D). However, a drastic reduction of and Vj was observed for the RGFLCP extruded by a twin-screw extruder. The mechanical, thermal properties, and the shear viscosity of the extruded RGFLCP decreased with the reduction of and Vj. The extruded RGFLCP prepared with a single screw extruder that was featured with 30 mm screw diameter and 30 L/D obtained the excellent properties with a notched impact strength of 103.4 J/m, tensile strength of 110.2 MPa, and flexural strength of 159.3 MPa. Its initial decomposition temperature (T−1%) and heat distortion temperature were 483.1°C and 256.4°C, respectively. POLYM. COMPOS., 37:370–378, 2016. © 2014 Society of Plastics Engineers
Co-reporter:Shuidong Zhang, Peng Wang, Lingcao Tan, Hanxiong Huang and Guo Jiang
RSC Advances 2015 vol. 5(Issue 18) pp:13296-13306
Publication Date(Web):06 Jan 2015
DOI:10.1039/C4RA13114B
Considering environmental protection and economic requirements, the use of recycled glass fiber reinforced flame retardant nylon 46 (RGFFRPA46) is of significant importance. In this work, the mechanical, thermal, rheological and flame retardant properties of the recycled RGFFRPA46 were evaluated by varying shear screws. To establish the relationship between the screw structure and the properties of RGFFRPA46, the carboxyl content (CC) and viscosity-average molecular weight () of PA46, the distribution and average length of glass fiber () and microscopic appearance of RGFFRPA46 were investigated. The results showed that the shear force resistance time of RGFFRPA46 increased with the increase of the shear strain and with the ratio of length to diameter of the used extruder. As a result, of PA46, and the percentage of glass fiber length (Vj), which was higher than critical length, decreased, whereas the CC of PA46 increased significantly. The mechanical and rheological properties were sensitive to these variations, particularly the decrease in impact, tensile, flexural strength and shear viscosity of RGFFRPA46. Furthermore, the influence of degradation on of PA46 and were negative to the thermal properties of RGFFRPA46 after extrusion. However, the flame retardant properties of RGFFRPA46 were independent of the degradation. All of them achieved a UL-94 V-0 classification, and passed the glow wire ignition temperature (775 °C) test along with LOI of 36.7%. When RGFFRPA46 was extruded by a single screw extruder with the lowest shear force, a decrease of only 5.8% was observed in mechanical properties with negligible reductions in thermal and flame retardant properties.
Co-reporter:Zhang Shuidong, Tan Lingcao, Liang Jizhao, Huang Hanxiong, Jiang Guo
Polymer Degradation and Stability 2014 Volume 105() pp:140-149
Publication Date(Web):July 2014
DOI:10.1016/j.polymdegradstab.2014.04.009
Considering environment protection and economic requirements, the reuse of glass fiber reinforced flame retardant PBT (GFFRPBT) is of significant importance. In this paper, the properties of reprocessed GFFRPBT (RGFFRPBT) including rheological, mechanical, thermal and flame retardant properties were evaluated. To explore the relationship between structure and properties of RGFFRPBT, the carboxyl content and intrinsic viscosity of PBT, average length of glass fiber and its distribution, and the microscopic appearance of RGFFRPBT were investigated. The results demonstrated that when GFFRPBT was injection molded for five cycles, the intrinsic viscosity of PBT, average length of the glass fiber and the percentage of glass fiber length, which was higher than critical length decreased, whereas, the carboxyl content of PBT increased significantly. The rheological and mechanical properties became sensitive to these variations: the shear viscosity, impact strength, tensile and flexural strength of RGFFRPBT decreased. Furthermore, the influence of degradation on the PBT molecular weight and the glass fiber length after the reprocessing cycles were negative on the thermal properties of RGFFRPBT. However, the flame retardant properties of RGFFRPBT was independent on the degradation; RGFFRPBT with five injection molding cycles could achieve a UL-94 V-0 classification 32.0 LOI, and pass the GWIT (775 °C) test. The results showed that, when GFFRPBT was reprocessed twice, its properties matched the requirements of electronic and electric fields well.
Co-reporter:Guo Jiang;Han-Xiong Huang ;Zhao-Ke Chen
Advances in Polymer Technology 2011 Volume 30( Issue 3) pp:174-182
Publication Date(Web):
DOI:10.1002/adv.20214
Abstract
Supercritical carbon dioxide (Sc-CO2) is a good plasticizer to improve the compatibility for nanocomposites or polymer blends. In this work, polylactide (PLA)/clay nanocomposites were compounded using a twin-screw extruder. Two extrusion methods were used, one with Sc-CO2 and another without Sc-CO2. Microstructures of nanocomposites and their mechanical properties were investigated. Their thermal behavior was analyzed using differential scanning calorimeter (DSC) and thermogravimetry analyzer. Results show that the layer spacing of clay in the nanocomposites was improved. Observed from transmission electron microscopy photomicrographs, it was shown that the clay was dispersed more homogeneously in the nanocomposites compounded with Sc-CO2. DSC traces show that cold crystallization appeared for nanocomposites, indicating that clay could act as a nucleating agent. Sc-CO2 was helpful in improving the thermal stability of nanocomposites. In addition, there existed a yielding phenomenon for nanocomposites during the tensile property measurement. With the preparation of Sc-CO2, the elongation at break and tensile strength for nanocomposites were increased. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 30: 174–182, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20214
Co-reporter:Guo Jiang;Han-Xiong Huang
Polymer Engineering & Science 2011 Volume 51( Issue 11) pp:2345-2352
Publication Date(Web):
DOI:10.1002/pen.22008
Abstract
Polypropylene (PP)/clay nanocomposite was melt-compounded using high shearing/mixing and chaotic mixing, the former provided by kneading block sections in twin-screw extruder and the latter by a convective screw. Effect of mixing type on rheological behavior and microstructure of nanocomposites was investigated. Rheological property development along twin-screw extruder was also tested. By numerical simulation, shear strain was calculated. Based on rheological analysis, the relationship between the shear strain and microstructure of nanocomposite was analyzed. Results show that chaotic mixing facilitates the dispersion of clay in PP matrix. Along twin-screw extruder, the complex viscosity of samples is increased, and melt yield stress of end-obtained samples is decreased with increase of the feeding rate. Observed from transmission electron microscopy photomicrographs, a better dispersion of clay in PP matrix was found when feeding rate is lowest, and the total strain calculated is largest at the lowest feeding rate. It is deduced that higher strain in flow field is important to obtain better dispersion and properties of polymer/clay nanocomposites. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.
Co-reporter:Guo Jiang;Han-Xiong Huang
Journal of Materials Science 2008 Volume 43( Issue 15) pp:
Publication Date(Web):2008 August
DOI:10.1007/s10853-008-2763-2
In this work, the online melt shear viscosity of polypropylene/nano-calcium carbonate composites was measured during the compounding to investigate the relationship between their rheological behavior and microstructure. Effects of dispersive mixing, distributive mixing, and chaotic mixing on online shear viscosity and microstructure of nanocomposites were analyzed. The results showed that the online shear viscosity of nanocomposites is lower than that of pure PP, when the nano-CaCO3 content is lower than 5, 10, and 15 wt%, compounded by high dispersive mixing, dispersive/distributive mixing, and dispersive/distributive/chaotic mixing, respectively. This is greatly related with the dispersion of nanoparticles in PP matrix. It is deduced that there exists a critical percentage (Φcr) of the nano-CaCO3 with size lower than 100 nm and a critical mean diameter (dcr). The shear viscosity is lower than that of pure PP when the percentage is higher than the critical percentage and the mean diameter is lower than the critical diameter. In this work, the critical percentage is 80% and critical mean diameter is 60 nm.
