Surface Modification of PET Fiber with Hybrid Coating and Its Effect on the Properties of PP Composites.

Surface modification fundamentally influences the morphology of polyethylene terephthalate (PET) fibers produced from abandoned polyester textiles and improve the compatibility between the fiber and the matrix. In this study, PET fiber was modified through solution dip-coating using a novel synthesized tetraethyl orthosilicate (TEOS)/KH550/ polypropylene (PP)-g-MAH (MPP) hybrid (TMPP). The PET fiber with TMPP modifier was exposed to the air. SiO2 particles would be hydrolyzed from TEOS and become the crystalline cores of MPP. Then, the membrane formed by MPP, SiO2 and KH550 covered the surface of the PET fiber. TMPP powder was investigated and characterized by fourier transform infrared spectroscopy, scanning electron microscope (SEM) and thermogravimetric analysis (TGA). TMPP-modified PET fiber was researched by X-ray diffraction and SEM. Furthermore, tensile strength of single fiber was also tested. PET fiber/PP composites were studied through dynamic mechanical analysis and SEM. Flexural properties of composites were also measured. The interfacial properties of PET fiber and PP matrix were indirectly represented by contact angle analysis. Results showed that the addition of TEOS is helpful in homogenizing the distribution of PP-g-MAH. Furthermore, TMPP generates an organic-inorganic 'armor' structure on PET fiber, which can make up for the damage areas on the surface of PET fiber and strengthen each single-fiber by 14.4%. Besides, bending strength and modulus of TMPP-modified PET fiber-reinforced PP composite respectively, increase by 10 and 800 MPa. The compatibility between PET fiber and PP was also confirmed to be increased by TMPP. Predictably, this work supplied a new way for PET fiber modification and exploited its potential applications in composites.

Impact of modification of carbon black on morphology and performance of polyimide/carbon black hybrid composites.

The composite films based on polyimide (PI) and chloride modified carbon black (CB-COCl) were prepared by conversion of biphenyltetracarboxylic dianhydride and 4,4'-oxydianiline in the presence of CB-COCl, followed by thermal imidization. The presence of chemical bonds between PI and CB-COCl, proved by FTIR spectra of the composites, has a considerable effect on the properties of PI films. Scanning electron microscopy (SEM) pictures of the PI/CB-COCl membranes showed changed morphology compared to reference membranes without CB-COCl. The thermal stability and structure of the composites were studied by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and X-ray diffraction (XRD), respectively. These hybrid films showed an increase in thermal decomposition temperature and a slightly enhanced glass transition temperature. On their mechanical properties, the modulus and ultimate strength of the hybrid films increased and elongation at break decreased with increased CB-COCl content. The surface free energy of polyimide films were determined by means of the contact angle measurements.

Grafting modification and structural degradation of multi-walled carbon nanotubes under the effect of ultrasonics sonochemistry.

Polyvinyl pyrrolidone (PVP) grafted multi-walled carbon nanotubes (MWCNTs) were prepared by the degradation effect of ultrasonics sonochemistry. PVP macroradicals formed by sonochemical degradation of a PVP solution were trapped by MWCNTs and grafted onto the surface of MWCNTs. It was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis that the PVP was covalently bonded on the MWCNTs. Transmission electron microscopy showed nanotubes in the grafted samples were shorter than the original MWCNTs due to the crushing effect of ultrasonics sonochemistry. Both the decrease in length of the MWCNTs and the PVP grafted onto them are beneficial for their dispersion in solvents.

Chemical modification of carbon black by a simple non-liquid-phase approach.

Chemical modification is the most popular and efficacious approach to improve dispersion stability for commercial carbon blacks in organic media. Even though this method has been used successfully in liquid systems, there have been few reports of chemical modification of carbon black in non-liquid-phase systems. In the present work, a simple non-liquid-phase approach to preparing modified carbon black with high dispersibility and stability in polar organic media from an industrial carbon black, N220, is reported. The treatment was carried out in a rheology mixer by blending carbon black with a low-molecular-weight organic compound, 3,9-bis-(1,1-dimethyl-2[beta-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl)-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80), under proper conditions. The modified carbon black had a smaller particle size than the original carbon black, as proven by dynamic light scattering and transmission electron microscopy, and it could be dispersed facilely in acetone to form a stable suspension. Time-of-flight secondary ion mass spectroscopy was used to detect the chemical presence of AO-80 fragments on the surface of the modified carbon black and consequently the modification mechanism.

Effect of ultrasonic separation on the structure and properties of diallyl phthalate prepolymer.

The bulk polymerization of diallyl phthalate (DAP) was carried out at high temperature (190 degrees C) without using any initiator, and the reaction was stopped before the gelation point in order to get the prepolymer of DAP. The mixture for the prepolymer and the monomer was successfully separated by a novel ultrasonic method for the first time, and the separation efficiency for the new method was obviously higher than that for the traditional reprecipitation. The product obtained by ultrasonic separation was characterized by infrared spectroscopy (IR), gel permeation chromatography (GPC) and iodine number measurement. It was shown that the average molecular weight of the prepolymer got by the ultrasonic method was lower than that of the prepolymer got by the multi-precipitation, moreover, the molecular weight distribution of the prepolymer got by the ultrasonic separation was broader. Besides, the residual unsaturation degree of the prepolymer separated by ultrasonic was slightly higher than that of prepolymer separated by reprecipitation.

Sonochemical preparation of carbon nanosheet from carbon black.

Preparation of carbon nanosheet via ultrasound irradiation of carbon black under ambient conditions was reported for the first time. The structure of resulting carbon nanosheet was characterized by TEM, HRTEM, EDX and AFM. The experimental results showed that the carbon nanosheet is composed of ordered graphite carbon layers with a thickness of several nanometers.