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2019, Volume 33 Issue 3 Publication date: 26 March 2019 Previous Issue Next Issue

Preparation and Flame Retardant Properties of Polylactide/Lanthanum Phenylphosphinate Composites

2019, 33 (3): 1-5; DOI: 10.19491/j.issn.1001-9278.2019.03.001

Abstract ( 501 )

Lanthanum phenylphosphinate (LaP) was synthesized by a simple method and then introduced into polylactide (PLA) to prepare a series of PLA/LaP composites. The thermal stability, flame retardancy and combustion properties of the resulting composites were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning experiments and microscale combustion calorimeter (MCC). The results indicated that the incorporation of LaP could enhance the flame retardancy of PLA, and the composites achieved an LOI of 24.8 vol% and a V-2 classification in the UL 94 vertical burning test when 30 wt% of LaP was added. TGA measurement confirmed that LaP could effectively enhance degradation temperature and char residue of the composites. MCC analysis indicated that a high LaP loading could significantly decrease the peak heat release rate and total heat release of the composites, thus reducing the fire hazard of the composites.

Comparative Study on Flame-retardant Effect of Two Compounds Containing Phosphaphenanthrene and Triazinetrione Groups on Rigid Polyurethane Foams

2019, 33 (3): 6-11; DOI: 10.19491/j.issn.1001-9278.2019.03.002

Abstract ( 560 )

The flame-retardant rigid polyurethane foams (RPUFs) containing tris-(3-DOPO-2-hydroxy-propyl)-1,3,5-triazine-2,4,6-trione (TGD)/tris-(3-DOPO-propyl)-1,3,5-triazine-2,4,6-trione (TAD) and expansible graphite (EG) were prepared by a box foaming method. The effects of TGD and TAD on the flame-retardant behaviors of RPUFs were investigated by limiting oxygen index (LOI), cone calorimeter test, TGA-gas chromatography-mass spectrometer (TGA-GC-MS) and scanning electron microscopy. The results indicated that the introduction of both TAD and TGD into RPUFs could improve their LOI but reduced their values of total heat release, average effective heat of combustion and heat release rate. The influence of TGD on these values was more significant than that of TAD. On the other hand, the TGD/EG/RPUF system exhibited a higher LOI value and a larger char yield than the TAD/EG/RPUF one.

Structure and mechanical property of PP/PA6/ionomer composites

2019, 33 (3): 12-16; DOI: 10.19491/j.issn.1001-9278.2019.03.003

Abstract ( 842 )

To improve the compatibility of PP and PA6, the PP/PA6/Surlyn blends were prepared by melt blending with a twin-screw extruder using ethylene-methyl methacrylate ionomer (Surlyn8920) as an additive. The structure and mechanical properties of the resulting blends were investigated by FTIR, XRD, DSC, SEM and tensile tests. The results indicated that the complexation between Surlyn8920 and PA6 reduced the crystallization and melting temperatures, crystalline degree and crystal perfection of PP and PA6. Moreover, the size of PA6 as a dispersed phase became smaller and its distribution became more uniform. The introduction of Surlyn8920 significantly modified the interfacial compatibility between PP and PA6, and an optimum compatibilizing effect was achieved by the addition of 7 wt% Surlyn8920. With this loading of Surlyn8920, the blends obtained the tensile strength at break of 40.59 MPa, elongation at break of 156.3 % and impact strength of 4.98 kJ/m2.

Synthesis and Characterization of Long-carbon-chain Polyamide-1012-Based Elastomer

2019, 33 (3): 17-21，27; DOI: 10.19491/j.issn.1001-9278.2019.03.004

Abstract ( 1190 )

A polyamide-based thermoplastic elastomer (TPAE) was synthesized by melt block copolymerization of a double-end carboxyl-terminated polyamide 1012 (PA1012) and polytetrahydrofuran ether glycol (PTMG). The chemical structure of the resulting block copolymer was identified by Fourier-transform infrared spectroscopy and its crystallization was analyzed by wide-angle X-ray diffraction. Moreover, its performance was investigated by differential scanning calorimetry, thermogravimetric analysis, mechanical measurements and solubility analysis. The results indicated that the as-synthesized elastomer has a melting point higher than 180 °C and a thermal decomposition temperature higher than 420 °C as well as excellent mechanical properties and solvent resistance. The TPAE developed by this work is considered as a type of high performance thermoplastic elastomer material.

Effect of Reinforced Fabric Structure on Mechanical Properties of Curved Composites

2019, 33 (3): 22-27; DOI: 10.19491/j.issn.1001-9278.2019.03.005

Abstract ( 534 )

To explore the influence of the microstructure of reinforcement fabric on the mechanical properties of curved composite, the basalt fabrics with different organizational structures including plain, twill, satin, and weft-free structure were immersed in a mixed solution of epoxy resin and curing agent, to prepare a series of curved composite materials by pressure composite molding in a special mold. The bending strength and flexural modulus of the curved composites were measured by a three-point bending test method. The impact properties, bursting strength and failure mechanism of the curved composites were studied. The results indicated that the basalt basalt-fiber-reinforced curved composites with plain weave reinforcement have optimum bending performance, but those with a satin structure have optimum impact optimum performance and similar the bending strength. On the other hand, the curved composites with the satin structure have slightly lower bursting strength than those with a twill structure.

Effect of Different Tougheners on the Properties of PLA/Wheat Straw Composite Material

2019, 33 (3): 28-31，37; DOI: 10.19491/j.issn.1001-9278.2019.03.006

Abstract ( 673 )

In this article, a type of biodegradable PLA/wheat straw composites were prepared by a compression-molding method using metallocene polyethylene (mPE) and POE as impact modifiers. The effects of type and loading of impact modifiers on the mechanical properties and water absorption of the composites were investigated and their crystalline and chemical structures were analyzed by XRD and FTIR spectroscopy. The results indicated that the Rockwell hardness and tensile, bending and impact strength of the composites presented an increasing trend first and then tended to decrease with an increase of mPE/POE content, When the content of impact modifierswas in the range of 5 wt%~10 wt%, the composites achieved optimumproperties.

Mechanical Properties and Crystallization of PA66/Modified PLA Blends

2019, 33 (3): 32-37; DOI: 10.19491/j.issn.1001-9278.2019.03.007

Abstract ( 561 )

A series of polyamide 66 (PA66)/polylactic acid (PLA) blends with different contents of PLA were prepared by a melt-blending method. The effect of PLA content on the fracture morphology, mechanical properties and crystalline properties of the blends after heat treatment were investigated. The results indicated that PA66 was partially compatible with PLA, and the blends achieved an increase in tensile strength by 93 % compared to pure PA66 when the content of PLA is less than 10 wt%. On the other hand, their elongation at break increased by a factor of 8.6 compared to PLA. The crystallization rate of PA66 increased and its crystallization time was shortened when less than 20 wt% of PLA was incorporated, indicating an improved crystalline property. Moreover, the tensile strength of the blends decreased significantly when the PLA content exceeded 20 wt%.

Study of Off-axial Tensile Behaviors of Triaxial Weave Fabric Reinforced Rubber Composites

2019, 33 (3): 38-42，49; DOI: 10.19491/j.issn.1001-9278.2019.03.008

Abstract ( 530 )

In this paper, the off-axial tensile properties of triaxial-weave-fabric-reinforced rubber composites were studied and a comparative investigation was performed on the off-axis tensile properties between the triaxial and plain-weave-fabric-reinforced rubber composites. Moreover, the influence of sample shape including rectangle shape and dumbbell shape on off-axial tensile of the composite was also analyzed. The results indicated that there was almost no change in the fracture strength and elongation at break of the triaxial-weave-fabric-reinforced rubber composites but a few of changes in their offset angle, showing the quasi-isotropy, whereas the plain-weave-fabric-reinforced rubber composites exhibited evident anisotropy. The dumbbell shape specimen was more suitable for the measurement of the off-axis tensile properties of the composite.

Effect of Talc and OMMT on Properties of Brominated Flame Retardant Polypropylene

2019, 33 (3): 43-49; DOI: 10.19491/j.issn.1001-9278.2019.03.009

Abstract ( 596 )

This paper reported an investigation on the synergistic effects of talc and nano-organic montmorillonite (OMMT) on the polypropylene (PP) compounds flame-retarded with decabromodiphenyl ethane (DBDPE). Moreover, the effects of talc, DBDPE and OMMT loadings on the limited oxygen index (LOI), vertical combustion performance, mechanical properties and combustion behavior of the PP compounds were studied extensively. The results indicated that there was a significant synergetic effect of talc and OMMT on the flame retardancy of PP with DBDPE. The PP compounds exhibited an improvement in flame retardant standard for vertical combustion and a decrease in LOI with an increase of the amounts of talc and DBDPE flame retardant, and there was a further improvement with the addition of OMMT. The heat release rate, total heat release, smoke production rate and total smoke production of the PP compounds decreased significantly with the addition of small amounts of OMMT. The mechanical properties such as tensile and impact strength of the PP compounds decreased to some extent with the addition of talc, DBDPE and OMMT. These results demonstrated that the better flame retardant efficiency and mechanical properties could be obtained in virtue of the synergistic effect of talc, DBDPE and OMMT.

Necking and Fusing Failure Mechanism of Preformed Micro Component in In-Mold Micro Assembly Molding Process

2019, 33 (3): 50-55; DOI: 10.19491/j.issn.1001-9278.2019.03.010

Abstract ( 437 )

How to avoid the necking and fusing failures of preformed micro component under the environment of high temperature melt filling flow is a critical scientific problem for the in-mold micro assembly process of polymer micro machine. In this paper, we established a mechanism model of necking and fusing failure for the preformed micro-component induced by high-temperature melt filling flow. The investigation results indicated that the direct driving force of necking and fusing failure for preformed micro-size shaft was derived from its strain softening. Once the strain softening was induced, the necking and fusing damages for preformed micro-size shaft might happen. The strain softening phenomena were controlled by the initial yield stress of preformed micro-size shaft and were negatively correlated with the secondary molding injection temperature. The initial yield stress of preformed PMMA micro-size shaft decreased by 40.1 % from 16.5 MPa to 9.89 MPa when the injection temperature increased from 200 ℃ to 240 ℃. The necking shrinkage of neck section increased from 44.5 % to 70 %. The higher the secondary molding melt injection temperature, the easier was the strain softening and necking fusing failure of preformed micro-size shaft.

Numerical Analysis of Buried Defective Polyethylene Pipeline under Combined Loads of Temperature and Surface

2019, 33 (3): 56-61; DOI: 10.19491/j.issn.1001-9278.2019.03.011

Abstract ( 412 )

To analyze the stress level of buried defective polyethylene pipeline under the combined load of temperature and surface, the pipe-soil interaction model was established by using ABAQUS, and the combined load of temperature and surface was realized through thermodynamic analysis. The effects of temperature and surface loads on the in-service pipeline was analyzed, and the influences of buried depth, surface load position, elastic modulus of soil, friction coefficient of pipe-soil on the maximum stress was discussed. The results indicated that the effect of temperature load on the stress of buried polyethylene pipeline could not be ignored under the working pressure required by the code. However, the maximum stress of the pipeline was finally located in the direction of 3 oclock in the inner wall under the influence of internal pressure and temperature load. This result was consistent with the final position law of the intact pipeline, in which the defect in the 3 oclock direction of cross section was most prone to failure. The effect of the buried depth of pipeline and elastic modulus of soil was much greater than that of the friction coefficient of pipe soil and offset distance of occupation pressure position.

Numerical Simulation of Water Injection Pressure Control Method in Short-Glass-Fiber-Reinforced Polypropylene Water-Assisted Injection Molding

2019, 33 (3): 62-67，86; DOI: 10.19491/j.issn.1001-9278.2019.03.012

Abstract ( 339 )

Based on the generalized non-Newton constitutive equation, a finite volume method was used to simulate the water-assisted injection molding of short-glass-fiber-reinforced polypropylene (PP) under the different water injection pressure control modes. The simulation results indicated that the change of water injection pressure control mode had a certain influence on the residual wall thickness and eccentricity rate of the water-assisted injection molded parts. The residual wall thickness between different groups was similar and the eccentricity rate was larger when using the polyline control mode. The residual wall thickness also became more uniform in the same group. Using the stepwise control method, the residual wall thickness was not similar under different groups, and the eccentricity rate was small. The residual wall thickness also changed significantly under the same group.

Preparation of Nanometer Calcium Carbonate Masterbatch with Different Processing Methods and Its Effect on Structure and Properties of Polylactic Acid Compounds

2019, 33 (3): 68-73，86; DOI: 10.19491/j.issn.1001-9278.2019.03.013

Abstract ( 591 )

Nano-CaCO3 masterbatch was prepared by using continuous mixer and twin-screw extruder and then were added to polylactic acid (PLA) for injection molding. The effect of processing methods of the masterbatch on the dispersion of Nano-CaCO3 in the PLA matrix was investigated by thermogravimetric analysis, scanning electron microscopy and rotational rheometer. The results indicated that the masterbatch prepared by a continuous mixing method was more advantageous to the dispersion of Nano-CaCO3 in the PLA matrix, which could reduce the complex viscosity of the compounds and increase their crystallinity. At the same amount of masterbatch, the compounds obtained a less decrease in tensile strength but a more significant reinforement effect when using the masterbatch prepared by a continuous mixing method.

Optimization of Adjusting Machine Parameters of Injection Molding for Car Storage Box Based on Orthogonal Experiment

Qian Wang

2019, 33 (3): 74-80; DOI: 10.19491/j.issn.1001-9278.2019.03.014

Abstract ( 495 )

This process may result in high labor and material costs. The adjusting machine parameters of injection molding for a car storage box were optimized by the orthogonal experiment and mold flow analysis. The optimum combination of process parameters for injection molding was obtained based on the two performance indexes of volume shrinkage and y-direction warpage. The most important parameters affecting the two performance indexes were the holding pressure and melt temperature, which should be adjusted first during the injection molding process. Injection molding production revealed that the injection-molded products were successfully confirmed and accepted by manufacturers. These results proved that the parameters for a certain performance index of plastic part could be effectively adjusted by using orthogonal experiment, and this method had a promising application prospect for other plastic and mould companies.

Study on Synthesis and Performance of Lanthanum Diitaconate Dibutyltin Used for PVC

2019, 33 (3): 81-86; DOI: 10.19491/j.issn.1001-9278.2019.03.015

Abstract ( 393 )

Lanthanum diitaconate dibutyltin was synthesized with dibutyltin oxide, maleic acid and lanthanum nitrate as raw material, and its structure was characterized by Fourier-transform infrared spectroscopy and elemental analysis. The thermal stability of lanthanum diitaconate dibutyltin used for PVC was studied by means of thermal aging oven method, Congo red testing method, torque rheometer and ultraviolet spectrometer. The synergistic effects of lanthanum diitaconate dibutyltin with pentaerythritol and calcium/zinc stearate were discussed respectively. The results indicated that lanthanum diitaconate dibutyltin had a good thermal stability when added into PVC alone, which could significantly depress the rapid generation of long chain polyene structure in PVC and retarded the thermal degradation of PVC. The combination of lanthanum diitaconate dibutyltin and pentaerythritol could increase the static thermal stability time of PVC and delay the change in initial color. The combination of lanthanum diitaconate dibutyltin and calcium/zinc stearate could reduce processing energy consumption and enhance the stretching and impact properties of PVC.

Study on Mechanical Properties of Several Flexible Packaging Filmsat Different Temperature and Humidity

2019, 33 (3): 87-92; DOI: 10.19491/j.issn.1001-9278.2019.03.016

Abstract ( 333 )

Based on the difference of climate in the north and south parts of China, three types of test environments were simulated to evaluate the mechanical properties of several flexible packaging films under different conditions of temperature and humidity, and some suggestions were proposed for a reasonable choice of packaging materials for different users. According to the new national standard, seven important mechanical properties were selected to be measured in terms of different test items. The experimental results indicated that the elongation at break, friction coefficient, moisture permeability, fog and wetting tension obtained in a high temperature and humidity test environment were higher than those in the other two environments, showing the maximum test values were 654.8 %, 0.633, 13.8 g/(m2·24 h), 5.8 % and 73 m·N/m, respectively. The tensile strength and the heat shrinkage rate achieved in a low temperature and humidity test environment were higher than those in the other two environments, exhibiting the maximum test values were 386.5 MPa and 3.2 %, respectively. Summarily, each type of films was found to present its own advantages and disadvantages in different performance tests, and the customers could select anyone according to their requirement in daily use.

Designof Hot-runner Bicolor Injection Mold for Valve Body Parts of Automobile

2019, 33 (3): 93-96; DOI: 10.19491/j.issn.1001-9278.2019.03.017

Abstract ( 506 )

This paper reported a study on the design process of the hot-runner bicolor injection mold for the automobile valve body. Based on the characteristics of the bicolor mold and relevant products, two types of thermoplastics were selected as the basic materials, i.e. PP/40 %PS blend and TPO. To meet the requirement of appearance, the two-plate style hot-runner point gate was adopted to ensure the automatic separation of the product and molten material at the gate point during the opening process. A special side core-pulling mechanism was designed, which was driven by spring force. This makes the slider and the limit block move mutually without separating, thus making the slider movement more stable and accurate. The independent hydraulic core-pulling was used to solve the problem that there are some special holes formed on the product. The actual production confirmed that the mold structure was reasonable and the product performance was steady, which met the requirement of production.

Design of Injection Encapsulation Mold for Inner Cover of Back Clamp Battery Used for Cell Phone

2019, 33 (3): 97-100; DOI: 10.19491/j.issn.1001-9278.2019.03.018

Abstract ( 417 )

The inner cover of the back clamp battery used for cell phone is a type of bi-component plastic products. Its skeleton frame in the middle part is composed of ABS, and its cladding layer in the Peripheral parts consists of TPU. Two Injection molds were specially designed for the injection molding of such a product. The first one involved a side-gate mold system with fan-shaped gates and a pushing block ejecting system in the middle parts of the product. The second one has a pin-point system with two gradient pinpoint gates and also has a pushing block ejecting system and four-sides cam-pin slides. The demoulding system adopted a pushing block ejecting system. High-quality products and good economic efficiency were obtained from the two molds in practical use.

Design of Extending Hot Runner Systemfor Inside-Gating Injection Mold Used for Medical Bottle Caps

2019, 33 (3): 101-105; DOI: 10.19491/j.issn.1001-9278.2019.03.019

Abstract ( 489 )

As an example of hot runner application for production of medical bottle caps, an inside-gating system was found to be required for the injection mold after analyzing the structure of plastic part. Therefore, an extending hot runner system was designed to solve the difficulty in the caps injection molding. The hot-half mold structure was analyzed and its technical highlights were summarized in this article. The designs of manifold, the extending nozzle and gate were described and calculated especially for power and expansion. Through the practical production, this extending hot runner system was found to improve the production yield and quality with a smooth molding process under the reasonable design.

Progress of the Structure and Catalytic Mechanism of One New PET Hydrolase

2019, 33 (3): 106-112; DOI: 10.19491/j.issn.1001-9278.2019.03.020

Abstract ( 582 )

This paper overviewed the disposal of polyethylene terephthalate (PET) waste, and the biodegradation and relevant influence factors of a new PET hydrolase PETase. The structure and catalytic mechanism of PETase were summarized, and the future research direction of the biodegradation of PETase were prospected.

Research Progress in VOCs Adsorbents and Adsorption Mechanisms

2019, 33 (3): 113-119; DOI: 10.19491/j.issn.1001-9278.2019.03.021

Abstract ( 592 )

Volatile organic compounds (VOCs) are another type of serious pollutant except for particulate matter and sulfur dioxide, and therefore the control of VOCs has become a public concern in recent years. The porous materials with an adsorption capacity play an important role in the treatment of VOCs. In this paper, the preparation methods, chemical composition, structural characteristics, adsorption properties and relevant mechanisms of a series of porous adsorbents were introduced, and the application of adsorbents for removal of VOCs in polymer processing was summarized. Moreover, the development prospects of adsorbents were discussed.

Variation Analysis in New Substance Application for Food Contact Materials and Articles in China, Europe and the United States

2019, 33 (3): 120-127; DOI: 10.19491/j.issn.1001-9278.2019.03.022

Abstract ( 443 )

This paper mainly discusses the regulations of the European Union, the United States and China on the new substance application for food contact materials and articles, including regulatory regulations, regulatory agencies, declaration procedures and data requirements. The paper also proposed some suggestions for the establishment of rapid evaluation procedure and new exposure assessment model, which could strengthen the new substance management to ensure the safety of food contact materials and articles in China.

Research Progress of Crosslinking Polyethylene Foaming Materials

2019, 33 (3): 128-135; DOI: 10.19491/j.issn.1001-9278.2019.03.023

Abstract ( 490 )

This paper reviewed the preparation method and application progress of crosslinked polyethylene foaming materials. These preparation methods mainly included compression molding method, extrusion method, foaming box method, rotation molding method and radiation method. Furthermore, the advantages and disadvantages in preparation process, cost and promotion of these preparation methods were analyzed. The application progress of crosslinked polyethylene foaming materials in filling materials, heat insulation materials, building materials and lightweight materials are also summarized. Finally, the development prospect of crosslinked polyethylene foaming materials was discussed.