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2019, Volume 33 Issue 4 Publication date: 26 April 2019 Previous Issue Next Issue

Study on Low-temperature Toughened Polyamide 6 with POE-g-MAH

2019, 33 (4): 1-5; DOI: 10.19491/j.issn.1001-9278.2019.04.001

Abstract ( 756 )

The toughening modification of nylon 6 with POE-g-MAH as an impact modifier was conducted, and the effect of POE-g-MAH content on the mechanical properties and flowability of nylon 6/POE-g-MAH compounds was investigated. Most of all, the impact toughness of the compounds at normal and low temperatures as well as under an extremely cold condition were studied intensively. The microstructure of compounds was further characterized by SEM. The experimental results indicated that the compound with 20 wt % of POE-g-MAH exhibited optimium mechanical performance and good impact toughness at low temperatures. Even at an extreme low temperature of -50 °C, the compounds containing 20 and 30 wt % of POE-g-MAH still kept good toughness. Compared to pure nylon 6, and the impact strength increased by 130% and 350%, and the elongation at break was improved by 195% and 230%. Moreover, the low-temperature tensile strength also increased with a decrease of temperature.

Study on Preparation and Properties of PLA/PHBV 3D-Printing Filament

2019, 33 (4): 6-11; DOI: 10.19491/j.issn.1001-9278.2019.04.002

Abstract ( 612 )

Polylactic acid (PLA)/poly(3-hydroxybutyric acid-co-3-hydroxyvalerate) (PHBV) blends were prepared by melt blending, and then the 3D printing standard samples were prepared by a fused deposition modeling (FDM) method. The effect of mass ratio of PLA and PHBV on the 3D printing performance was investigated. The results indicated that the PLA/PHBV blends were completely incompatible. The tensile strength of the blends and their 3D printed specimens decreased compared to pure resin, but their elongation at break increased with the addition of PHBV. The bending strength the impact strength of the blends were found to increase at first and then to decrease. The injection molded samples achieved the maximum tensile strength up to 43.31MPa and the maximum elongation at break of 5.37%. The 3D printed specimens exhibited the maximum tensile strength up to 49.16MPa and the elongation at break of 7.41%. Scanning electron microscopy revealed that there was a typical "island" distribution in the quenched sections of the blends and their 3D printed specimens, in which the PHBV phase was uniformly dispersed in the PLA matrix. With the increase of PHBV content, the cross section of the injection molded samples became rougher and the gap between the layers of the 3D printed specimens became smaller. This led to an increase in filling rate and an improvement in bonding performance.

Study on maleic anhydride-treated straw-reinforced thermoplastic starch composites

2019, 33 (4): 12-16; DOI: 10.19491/j.issn.1001-9278.2019.04.003

Abstract ( 617 )

In this work, wheat-straw (WS) was surface-treated with maleic anhydride (MA) and then melt blended with corn starch to prepare the MA-treated WS-reinforced thermoplastic starch composites. The effects of MA content on the mechanical properties, thermal stability, morphology and water resistance of the composites were investigated. The results indicated that the mechanical properties of the composites were improved at the WS content of 1 wt.% and the MA content of 4 wt.%. The composite also achieved the tensile strength of 2.76 MPa and the elongation at break of 158.24%. As for the thermal stability, the incorporation of MA-treated WS improved the maximum decomposition rate of the composites. Moreover, the composites showed a water contact angle of 83.6° at the MA content of 6 wt.%. The optimal content MA was determined as 4 wt.% for the composites on the basis of the investigation results.

Preparation and Adsorptive Property of Cyclodextrin/Graphene Oxide Composite for Cu²⁺

2019, 33 (4): 17-21; DOI: 10.19491/j.issn.1001-9278.2019.04.004

Abstract ( 629 )

The graphene oxide (GO) was prepared by a modified hummer’s method and then reacted with a proper amount of cyclodextrin solution, hydrazine hydrate and ammonia water to obtain a cyclodextrin/GO composite. The amounts of adsorption of the composite for Cu2+ were measured at different pH values, time and temperatures. The results indicated that the cyclodextrin/GO composite exhibited an excellent adsorption capability to Cu2+ in aqueous solutions, and its adsorption capacity reached 212.44 mg/g after 24 h under the neutral condition, presenting the adsorption efficiency of 83.46%. Such a result was mainly due to the large surface area of the graphene oxide and the electrostatic attraction of the surface oxygen-containing groups to Cu2+ as well as the cavity structure of cyclodextrin.

Effects of Oxidation Induction Time on Thermo-oxidation Aging Performance of High-Density Polyethylene

2019, 33 (4): 22-25; DOI: 10.19491/j.issn.1001-9278.2019.04.005

Abstract ( 1026 )

The effect of oxidation induction time on the aging characteristics of high-density polyethylene (PE-HD) induced by artificial thermo-oxidation aging at 100 °C was studied in this work. Furthermore, we compared and analyzed the variation of mechanical properties including tensile strength, impact strength and elongation at break at different aging time, and also investigated the variation of crystallinity and oxidation induction time of HDPE in different periods of induction during artificial thermo-oxidation aging. The results indicated the crosslinking between molecule chains played a key role in the initial stage of thermo-oxidation aging, but the chain breaking and degradation were predominant in the latter stage. The longer oxidative induction time for HDPE led to better resistance to thermo-oxidation aging during the thermo-oxidation aging process at 100 °C. Oxidation induction time can be adopted as a relative indicator for the evaluation of HDPE oxidation stability.

Preparation and Application of Malic-Acid Hyperbranched Copolymer for Scale Inhibition

2019, 33 (4): 26-32; DOI: 10.19491/j.issn.1001-9278.2019.04.006

Abstract ( 702 )

The malic-acid hyperbranched copolymer (HBP) was successfully prepared by melt polymerization using trimethylolpropane as a core and malic acid as an AB2 monomer, and its structure was characterized by FT-IR and GPC. Then, HBP was applied for the scale inhibition of circulating water. The effects of HBP dosage and system temperature on the inhibition efficiency of CaSO4 scale were studied. The results indicated that HBP exhibited excellent dispersibility and scale inhibition performance for CaSO4, and it achieved a scale inhibition rate of 95.2% for CaSO4 at an HBP concentration of 12 mg/L. Moreover, HBP also showed excellent inhibition efficiency when used in a wide temperature range. XRD analysis demonstrated that HBP could inhibit the growth of calcium scale crystals and reduce its crystallinity, thus inhibiting the scaling capability.

Study on Synergistic Flame Retardancy of Fluorinated Phosphate Ionic Liquid for Flexible Polyurethane Foam

2019, 33 (4): 33-38; DOI: 10.19491/j.issn.1001-9278.2019.04.007

Abstract ( 665 )

Flame-retardant flexible polyurethane composite foams (FPUF) were prepared, and the flame-retarding effects of melamine polyphosphate (MPP), expandable graphite (EG) and ionic liquid (IL) on FPUF were investigated. Moreover, the optimal mass ratio of three flame retardants was determined by oxygen index (LOI), and the effects of flame retardants on the flame retardancy and thermal stability of FPUF were analyzed by thermogravimetry and cone calorimetry (CCT). The results indicated that when the mass ratio of MPP : EG : IL was set as 7.5 : 7.5 : 2. In this case, the LOI of FPUF reached a maximum value of 27.5 vol.%. Thermal analysis showed that the char yield of FPUF with MPP/EG/IL was higher than those of pure FPUF and FPUF with MPP/EG. The CCT results demonstrated that there was a decrease in peak heat release rate, total heat, the amount of smoke released and the production rate of CO for FPUF. The carbon layer was found to become denser in the presence of ionic liquid. The combination of three flame retardants generated a synergistic effect to improve the flame retarding effect and therefore reduced the fire risk.

Study on supercritical carbon dioxide assists the hard- segment crystallization and foaming behavior of TPU

2019, 33 (4): 39-42; DOI: 10.19491/j.issn.1001-9278.2019.04.008

Abstract ( 712 )

The thermoplastic polyurethane (TPU) foam is prepared by one-step pressure relief method using supercritical CO2 as foaming agent. The hard-segment (HS) crystallization and foaming behavior of TPU assisted by CO2 are studied by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results indicate that, the polydispersity HS formed during blend process is beneficial for crystallization. And a more perfect crystal can form with higher foaming temperature and pressure. Furthermore, more crystals can be gained with elevated foaming pressure and the microporous foam is obtained when the pressure reaches 20MPa

Analysis of Counter Pressure Injection Molding on Dimensional Stability of Thick-walled Products

2019, 33 (4): 43-47; DOI: 10.19491/j.issn.1001-9278.2019.04.009

Abstract ( 640 )

To clarify the effect of counter-pressure on the dimensional stability of thick-walled plastic products, a series of experiments were performed for injection-molded thick-walled plastic products by using self-developed solutions. The influence of backpressure on the shrinkage of thick-walled plastic products was also observed and analyzed. Furthermore, a counter-pressure injection molding method is proposed. In this injection mold, a piston was incorporated into the cavity of the mold, and the pressure element was connected to the pressure element to provide backpressure. The injection pressure of the melt was used to push the piston to move, thus stabilizing the melt in the mold cavity. The pressure was maintained in real time, thereby reducing the internal stress of thick-walled plastic products and obtaining an ideal product with a small shrinkage rate. The experimental results indicated that the use of acrylonitrile-styrene copolymer as a raw material for counter-pressure injection molding of thick-walled plastic products could effectively reduce the shrinkage of thick-walled plastic products, thus achieving a better dimensional stability for thick-walled plastic products. Meanwhile, the holding time for pressure could also be significantly shortened, leading to an improvement in production efficiency.

Preparation and Properties of Super-hydrophobic and Super-lipophilic Polylactic Acid Electrospun Fiber Films with Bead Structure

2019, 33 (4): 48-53; DOI: 10.19491/j.issn.1001-9278.2019.04.010

Abstract ( 724 )

Polysiloxane (PSQ) particles were introduced into the poly(lactic acid) PLA matrix by physical mixing and immobilization, and then the PLA electrospun fiber film with a bead structure was constructed. The results indicated that the introduction of PSQ was beneficial to the formation of beaded fiber, and the formation of bead structure led to a significant increase in water contact angle and porosity of PLA fiber film. In particular, the immobilization treatment of PSQ resulted in a water contact angle of 158° and a porosity of 54%, which were improved by 5% and 50%, respectively, compared to pure PLA fiber film. Moreover, the hydrophobic properties and oil flux of the fiber film were also improved significantly. The immobilization of PSQ in the PLA could inhibit its migration during the hydrolysis process. These PSQ particles could remain in the fiber film for long time to enhance the hydrophobic properties of the fiber film, leading to excellent hydrolysis resistance.

Study on Warm Runner Injection of Plastic-packaged Motor

2019, 33 (4): 54-58; DOI: 10.19491/j.issn.1001-9278.2019.04.011

Abstract ( 460 )

Based on the characteristics of BMC materials, the principle of a warm runner injection process was discussed, and the main points of design for the BMC warm runner injection mold were analyzed. The manufacturability of the warm runner injection molding process was also studied in terms of two important injection-molding parameters: injection temperature and injection pressure. The results showed that the warm runner injection process could be applied in the injection molding process of plastic-packaged motor, in which the injection process without coagulation in casting system was realized and the deburring process was avoided for internal surface of the stator. This may brings considerably economic benefits.

Study of Temperature Distribution of Mold under Temperature Gradient in Rapid Heating Process

2019, 33 (4): 59-65; DOI: 10.19491/j.issn.1001-9278.2019.04.012

Abstract ( 653 )

In this paper, the heating process analysis based on a CFD method was conducted to investigate the effects of the power of electric heating rod, the distance between the groups and the longitudinal distance on the temperature response and surface temperature uniformity of the cavity surface. The results indicated that the temperature response rate of the cavity surface increased significantly with the heating power, and however, the surface temperature uniformity became worse. The surface temperature response rate of the cavity slightly decreased when shortening the group spacing of the heating rod, but the surface temperature uniformity of the cavity deteriorated significantly. The temperature response rate of the mold cavity surface decreased significantly with a decrease of the distance between the heating rod and the cavity surface, which almost did not generate any effects on the surface temperature uniformity. This study provides a theoretical reference for the mold design based on a rapid heating technology.

Synthesis of Dodecyl Phosphate Catalyzed with Supported PW/ MCM-22 Molecular Sieve

2019, 33 (4): 66-71; DOI: 10.19491/j.issn.1001-9278.2019.04.013

Abstract ( 625 )

The HMCM-22 molecular sieve was modified with phosphotungstic acid (PW) by an impregnation method, and the resulting composite catalysts were characterized by XRD, SEM, FT-IR. The results indicated that there was no change in the original structure and characteristics of the modified HMCM-22 molecular sieve. The productivity of monododecyl ester was improved significantly for the synthesis of mono-alkyl phosphate (MPA) through esterification of dodecanol and phosphorus pentoxide at a molar ration of 2/1, indicating that the esterification was promoted synergistically by the active center of composite catalysts, thus resulting in excellent catalytic performance. For the composite catalyst loaded with 4 wt.% PW, a high productivity of 90% was achieved when the amount of water was 9 g, the amount of composites catalysts in total reactants was 1.5 wt.%, the reaction temperature was set at 90 °C, and the reaction time was set as 4 hours. This suggests that the PW/HMCM-22 composite molecular sieve has an excellent catalytic effect.

Synthesis and Properties of Thermoplastic Biodegradable PBSeT Copolyesters

2019, 33 (4): 72-80; DOI: 10.19491/j.issn.1001-9278.2019.04.014

Abstract ( 927 )

A series biodegradable copolyesters, poly(butylene sebacate-co-terephthalate) (PBSeT), were synthesized by using terephthalic acid (TPA), sebacic acid (SeA) and butylene glycol (BDO) as raw materials through esterification and polycondensation. The effect of molar ratio of SeA and TPA on the structures, thermal, mechanical and degradation properties of PBSeT was studied. The weight average molecular weight of PBSeT was distributed in the range of 178300 to 214277 g/mol. The melt temperature and crystallization temperature of PBSeT decreased at first and then increased with an increase of the content of rigid monomer TPA. PBSeT exhibited the weakest crystallization capacity at the SeA/TPA molar ratio of 50/50. When the TPA content increased from 10 mol.% to 90 mol.%, the glass transition temperature of PBSeT increased gradually. The thermal stabilities of PBSeT copolyesters were relatively similar at different mass ratios. PBSeT also exhibited higher tensile strength at a higher content of TPA, and it reached a maximum value at the SeA/TPA molar ratio of 30/70. However, its elongation at break reached a maximum value of 1040% at the SeA/TPA molar ratio of 50/50. PBSeT presented a typical pseudoplastic fluid, and its complex viscosity, storage modulus and loss modulus increased gradually with an increase of angular frequency. The degradation experimental results of Aspergillus niger indicated that the degradation capability of PBSeT decreased with an increase of the content of TPA monomer.

A review of Microplastics in the environment and its effect on human health

2019, 33 (4): 81-88; DOI: 10.19491/j.issn.1001-9278.2019.04.015

Abstract ( 1554 )

With the broad applications of plastic products in industrial production and our daily life, the microplastic pollution problem become a new environmental issue and has been attracted more and more attention all over the world. Microplastics have been detected in a wide range in seas, rivers, lakes, soil and air. The researches on distribution, migration and ecotoxicological effect of microplastics on human and other organisms are still limited. This paper overviewed the distributions and sources of microplastics in air, water and soil extensively. Moreover, the migration and transformation of microplastics and its ecotoxicological effect on human health were discussed. The future research direction of research on microplastic pollution was also prospected.

Risk assessment and supervision of non-intentionally added substances (NIAS) in food contact materials and articles

2019, 33 (4): 89-95; DOI: 10.19491/j.issn.1001-9278.2019.04.016

Abstract ( 802 )

This paper discussed the sources of NIAS and then compares and analyses the regulatory requirements of NIAS in China, the European Union and the United States. Based on the current chemical risk assessment basis, this paper summarized the NIAS risk assessment processes and specific material risk assessment methods for food contact materials and articles. The safety limit of regulations, traditional method and threshold of toxicological concern are commonly used methods for the risk assessment of food contact materials and articles. Each of them has its own advantages and can generate a complement each other. This provided references for the management and control of NIAS in the manufacture enterprises of food contact materials and articles in China.

Development and Applications of Thermoplastic Honeycomb Plate Edge Banding Machine

2019, 33 (4): 96-99; DOI: 10.19491/j.issn.1001-9278.2019.04.017

Abstract ( 549 )

Based on the features of thermoplastic honeycomb plate, an experimental study was conducted to verify the feasibility and practicability of edge banding of thermoplastic honeycomb plate by hot pressing with its surface. The edge banding effect was perfect, durable, eco-friendly and economical. A banding machine suitable for thermoplastic honeycomb plate was designed and developed successfully, which could band the edge automatically in high efficiency. Moreover, a honeycomb pallet product was also developed successfully by the banding machine. These results promoted the application of thermoplastic honeycomb plate in logistics and home furnishing industry.

Design of automatic loading injection mold with double mold rotary insert

2019, 33 (4): 100-106; DOI: 10.19491/j.issn.1001-9278.2019.04.018

Abstract ( 531 )

Based on the requirements of automatic injection molding of plastic parts with embedded parts, we designed a double mold for injection molding of embedded parts in a two-color molding mode in this work. The mold was composed of two sets of sub-molds, one for automatic assembly of embedded parts and another for injection molding of plastic parts. The two sets of molds could be replaced with two sets of mold cavities through the reciprocating rotation and adjustment of the rotating support. In this case, the automatic injection molding of the plastic parts could be achieved after the insert was installed in the mold cavities of the injection mold. The use of insert automatic assembly mold can help to reduce the hidden danger of injection molding production and improve the efficiency of injection molding production. There are three sub-mechanisms in the insert-loading automatic mechanism, which include insert conveying sub-mechanism, insert position sub-mechanism and insert templates compressive bar. These sub-mechanisms could make full use of the open and close function of mold template and utilize the cylinder driving gears to achieve insert in the mold transport dynamic model of plunger, sequential arrangement and automatic pressure into the plunger. As a result, automatic installation for insert in mold cavity was realized. Such a design is novel and can help to reduce the cost of production automation. With the one opening and two ejecting mode, the injection mold could well perform the demolding of the plastic strip insert.

Analysis and Research on the US Military Standard MIL-PRF-22191F

2019, 33 (4): 107-110; DOI: 10.19491/j.issn.1001-9278.2019.04.019

Abstract ( 733 )

This article introduced the content of MIL-PRF-22191F 《BARRIERM MATERIALS， TRANSPARENT， FLEXIBLE，HEAT-SEALABLE》, and analyzed the requirements, which was established by MIL-PRF-22191F, for classification, construction, splices, form, rolls, sealing, workmanship and performance index of barrier materials having waterproof or low water vapor transmission characteristics for use in military packaging. After comparing and analyzing with other relevant standards, some suggestions for the application of this standard are put forward.

Current Situation and Development Trends of PVC and Its Stabilizers

2019, 33 (4): 111-119; DOI: 10.19491/j.issn.1001-9278.2019.04.020

Abstract ( 764 )

This article introduced the green eco-friendly characteristics and market situation of PVC and also discussed the development significance of PVC in China. Moreover, the market situation of heat stabilizers for PVC in China was analyzed and their development direction was discussed.

Review on Key Patent Technologies of Colorless and Transparent Polyimide Films

2019, 33 (4): 120-125; DOI: 10.19491/j.issn.1001-9278.2019.04.021

Abstract ( 806 )

This paper overviewed the key patent technologies of colorless and transparent polyimide films in their colorless and transparent property, heat resistance, dimensional stability, flexibility and so on. These reviews also provided some useful references for the relevant domestic enterprises to seize the technical development trend so as to hold some key patents rapidly.

Latest Research Progress in Hemicellulose Films

2019, 33 (4): 126-136; DOI: 10.19491/j.issn.1001-9278.2019.04.022

Abstract ( 603 )

The latest research progress in hemicellulose film was analyzed and summarized with respect to its application in food packaging materials, bio-medical and edible films fields. The mechanical and barrier properties of hemicellulose films were compared. The current researches on the substrates and modification of hemicellulose films were highlighted, and their development prospect was predicted.