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2019, Volume 33 Issue 6 Publication date: 26 June 2019 Previous Issue Next Issue

Preparation and Properties of Monoepoxy Compound-grafted Polyamide 6

2019, 33 (6): 1-7; DOI: 10.19491/j.issn.1001-9278.2019.06.001

Abstract ( 464 )

Polyamide 6 (PA6) was grafted with a monoepoxy compound, glycidyl neodecanoate (GND), through reactive extrusion. The molecular structure of grafted PA6 was characterized by infrared spectroscopy, and its crystalline, rheological and mechanical properties were also investigated. The results indicated that GND could well react with PA6 to form branched PA6 copolymers. The branched chains reduced the crystallization rate and crystallinity degree of PA6, resulting in a change in the mechanical properties of grafted PA6 accordingly. The optimum dosage of GND was found to be in the range of 1~3 phr. There was a decrease in tensile strength by 8 % when 1 phr of GND was grafted into PA6. On the other hand, the elongation at break and notched impact strength increased by 161 % and 35 % compared to those of pure PA6, respectively.

Study on Low-temperature Toughness of Polypropylene Flame Retardant with BDDP

2019, 33 (6): 8-11; DOI: 10.19491/j.issn.1001-9278.2019.06.002

Abstract ( 612 )

The article reported an investigation on the effects of resin type, content of benzene-1,(1-methyl-eehylidene)bis［(3,-5di-bromo)-4-(2,3-dibrono-propoxy)］ (BDDP) and temperature on the notched and non-notched impact toughness of flame retardant polypropylene (PP)under the low-temperature condition. The results indicated that the homopolymerization-type flame retardant PP exhibited better impact resistance than the copolymerization-type one at -10 ℃ when 15 wt% of BDDP was incorporated. As for the copolymerization-type PP with a commercial grade of EP300M, its low-temperature impact toughness dropped significantly when the content of BDDP was improved from 3 wt% to 15 wt%. This result suggested that there was a great effect of temperature on impact toughness of the flame retardant PP with DBBP.

Study on Properties of Polypropylene Filled with Refined Modified Fly Ash

2019, 33 (6): 12-18; DOI: 10.19491/j.issn.1001-9278.2019.06.003

Abstract ( 312 )

The waste fly ash obtained from coal-fired power plants was refined by physical ball milling, activated with a silane coupling agent, and then used as a filler to prepare polypropylene (PP) matrix composites by melt blending. The results indicated that, compared to pure PP, the composites exhibited an increase in bending strength by 11.5 %, in tensile strength by 10.7 %, and in impact strength by 34.1 % when using the fly ash only treated by ball milling. Moreover, there was an improvement in the melt flow index and thermal stability of the composites. When the fly ash was treated with a silane coupling agent and then used for PP, the resulting composites showed a further improvement in mechanical properties and thermal stability. Based on our experimental results, there was a good toughening effect on PP when 20 wt% of surface-modified fly ash was incorporated, thus leading to optimal comprehensive performance for PP composites.

Preparation and Properties of Plasticized Films Based on Peelable Adhesives

2019, 33 (6): 19-23; DOI: 10.19491/j.issn.1001-9278.2019.06.004

Abstract ( 393 )

Poly(vinyl chloride-co-vinyl acetate) resin was mixed with alkyl sulfonate plasticizer and heat stabilizer to prepare glass adhesives by means of a high-speed mixing equipment, and the morphology, mechanical properties and thermal stability of the obtained adhesives were investigated. The results indicated that the peelable adhesives achieved the optimum mechanical properties and morphological characteristics when the plasticizing temperature was set at 150 ℃ and the plasticizing time was set to 10 min. When 0.75 wt% of dibutyltin dilaurate thermal stabilizer was incorporated, the obtained plasticized films achieved an optimal thermal stability. The plasticized films also exhibited an optimum defoaming effect when 0.75 wt% of non-silicone polymer defoamer was added. In addition, there is no breaking-off and vesicles observed in peelable plasticized films after immersed in 20 wt% hydrochloric acid and sodium hydroxide solutions for 30 min. These films can be easily peeled in a large area.

Preparation of Ecologically Friendly ABS Resin with Low Odor/Low VOC

2019, 33 (6): 24-30; DOI: 10.19491/j.issn.1001-9278.2019.06.005

Abstract ( 613 )

The ABS resin with a low content of volatile organic compounds (VOC) was prepared by a supercritical extraction process and its preparation process was investigated. The effects of three types of chain transfer agents including dodecyl mercaptan,α-methylstyrene linear dimer and Methyl 3-mercaptopropionate on the total VOC content were also investigated. The results indicated that the ABS resin prepared with α-methylstyrene linear dimer had the lowest TVOC content, and the optimum amount of this linear dimer used for ABS resin is equal to 3.5 times of the amount of dodecyl mercaptan. A four-factor orthogonal design was conducted with extrusion temperature, residence time, vacuum degree, and the optimum amount of extracting agent, and the optimum process conditions was determined as a extrusion temperature of 250 ℃, a residence time of 1 min, a vacuum degree of 0.99, and the amount of extracting agent CO2 of 1.5 wt% corresponding to the yield of ABS resin.

Preparation and Application of Daul Monomers Solid Phase Grafted Polypropylene

2019, 33 (6): 31-37; DOI: 10.19491/j.issn.1001-9278.2019.06.006

Abstract ( 226 )

PP-g-malic anhydride (MAH)/styrene (St) was prepared by a twin-monomer solid phase grafting method. The optimum condition was determined by orthogonal experiments with a reaction temperature of 120 ℃, a reaction time of 1 h, a St/MAH molar ratio of 1.2∶1, a MAH/PP mass ratio of 0.14/1, and a BPO/PP mass ratio of 0.02/1. The characterization results of FTIR and NMR spectroscopy indicated that MAH and styrene were successfully grafted into PP by free radical copolymerization. DSC and XRD investigations indicated that PP presented α-form crystals without any changes before and after grafting. However, the crystallinity degree of PP decreased, and its crystallization temperature increased. As a compatibilizer, the incorporation of PP-g-MAH/St enhanced the impact strength of PP compounds.

Properties of Sulfonated Polysulfone Proton Exchange Membranes Based on Post-Sulfonation

2019, 33 (6): 38-43; DOI: 10.19491/j.issn.1001-9278.2019.06.007

Abstract ( 362 )

Epoxidized polysulfone (OPSF) was prepared by incorporating epoxy group into the backbone of polysulfone (PSF) via Friedel-Crafts alkylation reaction with epoxy chloropropane, and then a novel type of sulfonated polysulfone with the side chain of naphthalene sulfonic acid (PSF-NS) was obtained by the reaction of OPSF with 2-naphthol-6,8-disulfonic acid dipotassium. The chemical structure of PSF-NS was characterized by FT-IR and 1H-NMR spectroscopy, and the corresponding proton exchange membranes (PEMs) were prepared by a solution casting method. The effects of temperature on the performance including ion exchange capacity, water uptake, swelling ratio and proton conductivity of PEMs were studied extensively. The experimental results indicated that the resulting PEMs exhibit an excellent dimensional stability at a high water-sorption rate compared to other types of side chain aromatic PEMs. The water uptake, swelling ratio and proton conductivity of PEMs increased with an increase of temperature. The water uptake of the PEMs with a sulfonated group amount of 1.43 mmol/g was 29.6 wt% and 43.1 wt% at 25 and 85 ℃, respectively, and the corresponding swelling ratios were 25.2 % and 56.2 %. Its methanol permeability was only 16.8×10-7 cm2/s, which was lower than that of Nafion115 membranes at the same condition.

Effect of Bulk Photo-crosslinking on Properties of Thermoplastic Starch Plastics

2019, 33 (6): 44-49; DOI: 10.19491/j.issn.1001-9278.2019.06.008

Abstract ( 387 )

Thermoplastic starch (TPS) was prepared by twin-screw extruder with benzophenone as a photoinitiator and glycerin as a plasticizer, and the effect of UV irradiation time on the mechanical properties, dynamic thermo-mechanical properties, thermal stabilities and water resistance of the resulting TPS were investigated. The results indicated that an optimum crosslinked network structure was formed with UV irradiation for 15 min, which led to an effective enhancement in mechanical properties and water resistance. The tensile strength, bending strength and impact strength of TPS were 4.57 MPa, 7.1 MPa, 69.39 kJ/m2, respectively, and its storage modulus was also improved. Moreover, the glass transition temperature reached a maximum value at this condition with a Tβ of -35.63 ℃ and a Tα of 53.96 ℃. The peak temperature of TPS corresponding to the maximum decomposition rate increased from 317.81 ℃ to 330.48 ℃, and its contact angle increased from 42.3 ° to 77.2 °, indicating the water resistance and water absorption of TPS were improved effectively.

Preparation and Properties of Carbon Fiber Reinforced Polypropylene Composite Pipes

2019, 33 (6): 50-55; DOI: 10.19491/j.issn.1001-9278.2019.06.009

Abstract ( 366 )

In this work, the pipes based on the polypropylene (PP)/carbon fiber (CF) composites were prepared by melt extrusion using different compatibilizers. The effects of CF lengths and contents and compatibilizer types on the mechanical properties, longitudinal retraction rate and blasting strength of the pipes were investigated by means of a long-term pressure test instrument, computer-controlled electronic universal test machine, combined digital display and scanning electron microscope. The results indicated that the introduction of CF as a high modulus and low retraction filler reduced the overall longitudinal shrinkage of PP/CF composite pipes and enhanced the burst strength of the pipes. Meanwhile, the addition of compatibilizer improved the mechanical properties of pipes significantly.

Study on Graphene-Modified PVDF Membrane Fabricated by Supercritical CO₂-Induced Phase Separation

2019, 33 (6): 56-62; DOI: 10.19491/j.issn.1001-9278.2019.06.010

Abstract ( 405 )

A type of graphene-modified polyvinylidene fluoride (PVDF) membranes were fabricated by supercritical CO2-induced phase separation using DMF as a solvent, and their morphology, thermal stability, thermodynamic properties, crystal transformation and hydrophilicity were studied. The results indicated that the microporous membranes obtained a good network structure at a low content of graphene under the process conditions of 8 MPa and 45 ℃. The pore size and roughness of the membranes were found to decrease, and however their hydrophilicity and thermal stability were improved. In addition, the introduction of graphene had little effect on thermodynamic properties but enhanced the transition of crystal form to form more β or γ crystals.

Study on Failure Mode and Burst Pressure of Electrofusion Joints of Polyethylene and Its Composite Pipes

2019, 33 (6): 63-68; DOI: 10.19491/j.issn.1001-9278.2019.06.011

Abstract ( 395 )

To analyze the stress distributions of electrofusion joints of polyethylene (PE) and its composite pipes, a finite element model of these joints subjected to internal pressure and axial force was established by means of the Abaqus finite element analysis software. The effects of pipe type and strength on the failure mode and burst pressure of electrofusion joints were investigated, and then short-term burst tests were conducted to verify the model. The results indicated that failure mode of electrofusion joint of PE pipe presented a ductile failure. The strength of reinforced thermoplastic pipe (RTP) influenced the failure mode and burst pressure of electrofusion joints. The failure mode transferred from pipe failure to electrofusion coupler failure with an increase of strength. The burst pressure increased with the strength of RTP at first and then tended to became stable.

Optimization of Process Parameters of Fused Deposition Modeling Based on Orthogonal Experiment

2019, 33 (6): 69-75; DOI: 10.19491/j.issn.1001-9278.2019.06.012

Abstract ( 426 )

Commercial PLA filament was used as a fused deposition modeling (FDM) 3D printing material, and its tensile strength and notched impact strength were taken as optimization indexes to design orthogonal tests. The PLA parts were fabricated with an FDM printer, and the effect of layer thickness, printing speed, nozzle temperature and filling angle on the mechanical performance of the resulting parts were investigated by an orthogonal analysis method. By means of the comprehensive scoring method and comprehensive balance methods, the optimal printing process parameters were obtained and the correctness of the test results was verified. The results indicated that the mechanical properties of 3D-printed parts were optimum when the layer thickness is 0.3 mm, the printing speed is 90 mm/s, the nozzle temperature is 220 ℃, and the filling angle is 45 °/45 °.

Study of Bursting Properties of Triaxial Weave Fabric Reinforced Rubber Composites

2019, 33 (6): 76-81; DOI: 10.19491/j.issn.1001-9278.2019.06.013

Abstract ( 451 )

In this paper, the bursting properties of triaxial weave fabric (TWF) and its reinforced rubber composite (TWFR) were evaluated, and the effect of bursting speeds and shapes including conical, hemispherical and plane impactors on the bursting properties were investigated. Moreover, a comparative study was conducted for TWF and TWFR with plain woven fabric and its reinforced rubber composites. The results indicated that blunter impactor generated the higher load-displacement slopes, larger fracture loads, and smaller initial damage displacements. The bursting morphologies of these samples indicated that TWF had a stable structure, and the damages were not easily expanded after breakage. As the bursting speed increased, the slope of load-displacement curve and fracture load of TWFR increased, but the initial damage displacement decreased. There was no significant change observed in the load-displacement curves of TWF.

Application of Mixture Design in Formulation of Polypropylene Compounds for Automobile

Dunkan WANG

2019, 33 (6): 82-88; DOI: 10.19491/j.issn.1001-9278.2019.06.014

Abstract ( 337 )

Mixture design is a very useful method to solve the problems in formulation determination of materials. This paper introduced the applications of mixture design in the formulation design for two polypropylene (PP)-based automotive materials, FL-TD20 and JL-TD20, by means of the Minitab statistical software.An effective regression equation of melt flow rate was deduced for FL-TD20 product. As for the mixture design of JL-TD20 product, three components were found to have no significant influence on the density and ash content of PP compounds, and however therewasa remarkable effect from them on the melt flow rate, notchedimpact strength, tensile strength, thermal deformation temperature and bending strength of the compounds. The regression equation based on five performance indexes was deduced, andthe ranges of qualified formulations based on performance indexeswere further determined. The predicted values were found to have the differences less than 5 % according to the validation of experimental results.

Study on Double-layer-encapsulated Ammonium Polyphosphate and Its Application for Flame-retardant PP

2019, 33 (6): 89-94; DOI: 10.19491/j.issn.1001-9278.2019.06.015

Abstract ( 284 )

Ammonium polyphosphate (APP) was encapsulated with formaldehyde-melamine resin and epoxy resin in a monolayer or double-layer mode and then used for flame-retardant modification of polypropylene (PP). The structure and performance of the resulting APP and relevant flame-retardant PP were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, horizontal vertical burning experiment and limiting oxygen index measurement. The results indicated that the water solubility of the encapsulated APP decreased, and its expansion ratio and flame-retardant efficiency were improved. The double-layer-encapsulated APP has lower water solubility and better flame-retardant effect than the mono-layer-encapsulated one. Compared to pure APP, the encapsulated APP had less effect on the mechanical properties of PP and stronger interface bonding with PP matrix.

Overview of Phthalate Plasticizers, Current Regulations and Standards

2019, 33 (6): 95-105; DOI: 10.19491/j.issn.1001-9278.2019.06.016

Abstract ( 743 )

Phthalate plasticizers are an important class of additives for improving the performance of plastic products. This type of plasticizers is commonly used in packaging, decoration materials and so on. As some of phthalates have toxicity, many countries and organizations have paid more attention to restrict the usage of phthalate plasticizers. This article presented an overview for phthalate plasticizers. We briefly reviewed the toxicities and metabolisms of phthalates and also introduced the test methods of phthalates and relevant preparation for specimens. We also summarized the current situation of regulations and standards for phthalates both in China and overseas. Some suggests on future research of plasticizers and other opportunities were further proposed in this article.

Exposure Assessment of Substances Migrated from Food Packaging Materials Based on Tiered Approach

2019, 33 (6): 106-111; DOI: 10.19491/j.issn.1001-9278.2019.06.017

Abstract ( 383 )

The safety of food packing material has attracted a great deal of attention from the publics. The utilization of a risk assessment for the migrant is considered as an effective method to ensure human health. The exposure assessment plays an important role in risk assessment of food safety. There are many methods for conducting exposure assessment, which include deterministic approach and probabilistic approaches. Through the introduction and comparison of these two types of approaches, some appropriate methods are selected by using the theory of tiered approaches for exposure assessment. The deterministic approaches including EU, FDA and refined deterministic approaches are superior due to the feasibility and simplification. When the result of deterministic approach cannot judge the effect of exposure assessment, the probabilistic approach can be applied for the further process. Probabilistic approach can get more accurate exposure results, and however it requires more data as well as an available model.

Optimization of Injection Molding Process Parameters for A Cylindrical Inner Parts in Mode of One Mold and Two Cavities

2019, 33 (6): 112-116，126; DOI: 10.19491/j.issn.1001-9278.2019.06.018

Abstract ( 577 )

Based on the analysis of the interior decoration model of column A, the gate was determined as a latent side gate, four points of feeding was selected, and the mold was designed a structure with “one mold and two cavities”. According to the analysis of injection molding process the melt temperature was determined as 232 ℃, the holding pressure was set to 105 MPa, the holding time was set as 7 s, and the cooling time was set as 29 s. The plastic volume shrinkage rate in average was 3.42 % for the injection-molded part under this condition. After verifying this group of technical parameters in injection molding, the acoustic port characteristics of the interior trim of column A are formed perfectly, and there is no defect caused by the slender internal flow passage. The clearance between the overall contour and fixture was within the allowable range.

Design of Injection Mold for Six-time Core-pulling Composite Mechanism of Eight Sliders of Sonar Surface Shell

2019, 33 (6): 117-126; DOI: 10.19491/j.issn.1001-9278.2019.06.019

Abstract ( 308 )

Combined with the requirements for automatic formation and also considering ofa difficulty in mold release, an injection mold with one cavity with 2point gates and three plate die was designed by means of CAE analysis and CAD structure-aided design technology. Two point gates were designed for the injection mold cavity, and the exhaust of the cavity was carried out by using the gap between the inlay pieces with a dimension less than 0.02 mm. A 14-independent-waterway system was adopted for the cooling system to ensure the uniformity of shrinkage deformation for the plastic parts. To overcome the difficulty in demolding of plastic parts, three cylinder-driven slider mechanisms were designed to conduct the demoldingof the characteristic exterior walls, and a composite mechanism with 8 sliders and 6-time pulling core was designed to conduct the core-pulling demolding of the characteristic interior walls. In the inner-wall demolding mechanism, the first cylinder drive completed two core-pulling operations and one slider displacement at first and then completes partial demolding. This provides a space for core-pulling action and the subsequent core-pulling action of the slider. Furthermore, the second cylinder drive completes one core-pulling operation and two core-pulling operations, thus realizing the complete non-interference demolding for the inner wall of the plastic parts. With a reasonable structure, this mechanism has a reliable operation and good practicability.

China Plastics Industry(2018)

2019, 33 (6): 127-131,146; DOI: 10.19491/j.issn.1001-9278.2019.06.020

Abstract ( 607 )

The general situation about the plastic industry of China in 2018 was reviewed. On the basis of the data of plastic industry, the apparent consumption of plastics, the amount of plastic waste, the amount of recycled plastics and the utilization rate of recycled plastics in 2018 are analyzed and calculated. Meanwhile, the relationship between plastics and environment was discussed.

Research Progress in Photodegradable Polymers

2019, 33 (6): 132-138; DOI: 10.19491/j.issn.1001-9278.2019.06.021

Abstract ( 518 )

This paper introduced the photodegradation mechanisms of copolymerization-type and additive-type photodegradable polymers based on Norrish reaction, overviewed the development of photodegradable polymers in China and overseas, and also analyzed the advantages and disadvantages of various photodegradable polymers. Furthermore, the problems in the development of photodegradable polymers and the relevant resolution were proposed. Finally, the future development prospects of photodegradable polymers were discussed.

Research Progress in Modification of Polymers with Coal and Its Solid Wastes

2019, 33 (6): 139-146; DOI: 10.19491/j.issn.1001-9278.2019.06.022

Abstract ( 377 )

The worldwide research progress in the modification of polymers with coal and its solid wastes including fly ash, coal gangue and coal slime was reviewed, and the characteristics and research keystones of various modified polymer systems were introduced. The physical blending method can effectively improve the thermal stability, mechanical and antistatic properties of compounds. The future research directions and development trends of polymers modified with coal and its solid wastes were prospected. These trends included the further decrease of particle size, the improvement of interface compatibility between the coal and its solid wastes and the matrix, the enhancement of theoretical study on microscopic interface structure and enhancement mechanism of composites, the development of new functional composite materials, the simplification of the molding progress and the industrialization of the relevant composite materials as soon as possible.