Jinliang Qiao

Effect of elastomeric nanoparticles on toughness and heat resistance of epoxy resins

A new composite consisting of epoxy resin and elastomeric nanoparticles with high toughness and high heat-distortion temperature is prepared. The size of the nanoparticles used was less than 90 nm. The excellent properties of the composite seem to be due to stronger interactions between the carboxyl groups of the nanoparticles and the epoxy groups of the resin, and to enhanced hydrogen bonding between the nitrile groups of the rubber and the hydroxyl groups of the resin.

Recent advances in polyolefin technology

Polyolefin resins are the major plastics consumed in the world and are the subject of many new research works. This review will discuss how polyolefin technology has been developed in the past decade, with particular attention to new products, catalysts, polymerization processes and additives around the world as well as in China.

Polyamides derived from piperazine and used for hot-melt adhesives: synthesis and properties

Abstract The polyamides, used for hot-melt adhesives, were synthesized from dimer acid, sebacic acid, ethylenediamine and piperazine. The effect of the content of piperazine and sebacic acid on properties of the polyamides, such as glass transition temperature, crystallinity, softening point, mechanical properties and low-temperature properties, was investigated. The adhesion strength of the resultant hot-melt adhesives was also studied. DSC thermograms of the polyamides showed that the glass transition temperature (Tg) and crystallinity of the polyamide decreased as the molar fraction of piperazine increased; Tg almost did not change as the mole fraction of sebacic acid increased from 6.2% to 12.2%, while crystallinity of the polyamide increased. Softening point, mechanical properties, low-temperature properties and adhesion properties were also, to some extent, changed as the content of piperazine and sebacic acid varied. The polyamide had the best properties in all aspects when the molar fraction of piperazine was about 25% and the mole fraction of sebacic acid, about 8.2%.

Effect of gamma irradiation on ethylene-octene copolymers

Abstract Two ethylene–octene copolymers (POE) were irradiated with 60 Co gamma radiation and influence of irradiation atmosphere, absorbed dose and heat treatment of samples on the crosslinking were studied. Thermal properties and crystalline morphology of non-irradiated and irradiated POE were determined by using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXS), respectively. The Charlesby–Pinner equation was used to describe the relationship between absorbed dose and sol fraction. The gel fraction of irradiated POE was lower and decreased with the increase of octene content when irradiated in oxygen, compared to irradiation in nitrogen atmosphere. The gel fraction increased significantly with the increasing of absorbed dose for the two copolymers. Heat treatment of samples prohibited the crosslinking of irradiated POE. The DSC results indicated that a subtle change of thermal properties of POE was observed before and after gamma irradiation at low dose. No change was found from the WAXS spectra of non-irradiated and irradiated POE. For heat-treating samples, the Charlesby–Pinner equation can not fit perfectly with the relationship between the sol fraction and absorbed dose, but it fits well with the crosslinking reaction of POE pellets.

The study of rubber-modified plastics with higher heat resistance and higher toughness and its application

For rubber-modified plastics, toughness enhancement is generally at the cost of heat resistance. Of significance, this paper reported a finding that rubber-modified plastics with a special morphology could enhance toughness and heat resistance cooperatively. The special morphology was such that an interface in situ formed between plastic matrix and rubber particle had higher hardness than plastic matrix. As a result, the hard interface not only helped rubber soft component integrate with plastic matrix by covalent bonds to impart plastic matrix high toughness, but also covered rubber nanoparticles as hard shells to protect them from deforming at high temperature. The special morphology had been achieved in rubber-modified epoxies and phenolic molding material. The forming mechanism of the hard interface was studied in detail with AFM, DSC and in situFTIR, by using rubber-modified epoxy resin as an example. The finding could be applied to any rubber-modified plastics as long as the special morphology could be realized.

A new family of thermoplastic photoluminescence polymers

In order to overcome the drawback of traditional photoluminescence materials, which are usually opaque, expensive and non-thermoplastic, a new family of photoluminescence alternate copolymers made from maleic anhydride and different olefin derivatives with very low cost have been developed and are reported in this paper. The new photoluminescence polymers are all transparent-thermoplastic fluorescence polymers and the photoluminescence polymers made from maleic anhydride and styrene or its derivatives are all phosphorescence polymers, which are the first reported family of phosphorescence polymers without traditional luminous groups. A transparent and thermoplastic photoluminescence material with low cost has been a dream of both academia and industry for many years because it is an extremely important material for agriculture, LEDs, organic optoelectronics, anti-counterfeiting materials, coatings, illuminants, displays and many other areas; therefore, it is believed that this new family of photoluminescence polymers can contribute greatly to the sustainable development of our society.

Polymer-supported catalysts for clean preparation of n-butanol

A new type of RANEY® metal catalyst supported by polymer was developed for the clean preparation of n-butanol. Unlike traditional supported catalysts, the newly developed alkalescent polyamide 6 (PA6) supported RANEY® nickel catalyst provided a 100.0% conversion of n-butyraldehyde without producing any detectable n-butyl ether, the main byproduct in industry. The significantly enhanced catalyst selectivity of the polymer-supported RANEY® metal catalyst was attributed to the elimination of the acid-catalyzed side reaction associated with RANEY® metals and traditional catalyst supports, such as Al2O3 and SiO2. By eliminating acid-catalyzed side reactions, therefore, green chemistry could be achieved through reducing resources and energy consumption in chemical reactions. Furthermore, the preparation and recycling of the polymer-supported catalysts are also much more eco-friendly than for traditional Al2O3-/SiO2-supported catalysts. The methodology developed in this study to use alkalescent polymers as the catalyst support could be applied to the whole catalyst family, including a series of important RANEY® metal catalysts (e.g., RANEY® nickel, RANEY® cobalt, RANEY® copper) used routinely in the chemical industry.

One-step process to make electrically conductive thermoplastic vulcanizates filled with MWCNTs

Electrically conductive thermoplastic vulcanizates (TPVs) filled by multi-walled carbon nanotubes (MWCNTs) are prepared by a simple one-step melt mixing process, based on linear low density polyethylene (LLDPE) and ultrafine full-vulcanized rubber particles (UFRP). An ideal morphology with controlled localization of MWCNTs in continuous LLDPE matrix and appropriate size of finely-dispersed UFRP can be achieved at the same time. The controlled localization of MWCNTs in the continuous phase facilitates the formation of conductive pathway, and thus the volume resistivity of the as-prepared LLDPE/UFRP/MWCNTs thermoplastic vulcanizates is significantly decreased. The results show that both the blend ratio of LLDPE/UFRP and the loading of MWCNTs have remarkable effect on the volume resistivity. Significantly, the electrically conductive TPVs exhibit good mechanical properties duo to the fine dispersion of UFRP in LLDPE. The added MWCNTs are capable of imparting reinforcement effects to thermoplastic vulcanizates with just a slight loss of stretchability and elasticity.

Intrinsically Conductive Polymer Fibers from Thermoplastic trans-1,4-Polyisoprene

Herein, we report a new strategy to prepare conductive polymer fibers to overcome the insurmountable weakness of current conductive polymer fibers. First, special thermoplastic polymers are processed into polymer fibers using a conventional melt-spinning process, and then the nonconductive polymer fibers are converted into intrinsically conductive polymer fibers. Using this new strategy, intrinsically conductive polymer fibers have been prepared by melt spinning low-cost thermoplastic trans-1,4-polyisoprene and doping with iodine, which can be as fine as 0.01 mm, and the resistivity can be as low as 10(-2) Ω m. Moreover, it has been found that drawing can improve the orientation of trans-1,4-polyisoprene crystals in the fibers and, thus, the conductivity of the conductive polymer fibers. Therefore, conductive fibers with excellent conductivities can be prepared by large drawing ratios before doping. Such conductive polymer fibers with low cost could be used in textile, clothing, packing, and other fields, which would benefit both industry and daily life. The newly developed method also allows one to produce conductive polymers of any shape besides fibers for antistatic or conductive applications.

Effect of nano-fillers on conductivity of polyethylene/low melting point metal alloy composites

A novel method for preparing conductive polyethylene (PE) composites has been developed. In the method, the powder of low melting point metal alloy (LMPA) is filled into the PE matrix by using twin screw extruder at a temperature below the melting point of the LMPA, and followed by a die drawing process at a temperature around the melting point of the metal alloy. It has been found that die drawing process, repeating the die drawing process and adding nano-fillers, such as montmorillonite (MMT) and multi-wall carbon nanotubes (MWCNTs), all help reduce the metal particle size in the PE matrix, thus improve the conductivity of the composite. The conductivity improvement is attributed to an increased number of the smaller metal particles. Therefore, conductive composites of polymer/metal alloy/nano-filler with high conductivity are possible to be prepared by using the new method.