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2016, Volume 30 Issue 12 Publication date: 26 December 2016 Previous Issue Next Issue

Research Overview of Test Methods for Pressure Sensitivity of Polymer Melt Viscosity

2016, 30 (12): 1-8 ; DOI: 10.19491/j.issn.1001-9278.2016.12.001

Abstract ( 545 )

The article reviewed the applications of export pressurization method, double piston method and drag flow method for the study of pressure sensitivity of polymer melt and also introduced the basic principles and structures of experimental setup as well as the research results obtained from these three methods. Moreover, the specific applications of three methods were enumerated, and a new method for the test of pressure sensitivity was also proposed.

Effect of Different Mixing Equipments on Properties of PPO/PA66 Alloys

2016, 30 (12): 9-12 ; DOI: 10.19491/j.issn.1001-9278.2016.12.002

Abstract ( 623 )

This work investigated the influence of three kinds of continuous mixing equipments, i.e. intermeshing corotating twinscrew extruder, intermeshing counterrotating twinscrew extruder and Buss kneader, on properties of polyphenylene oxide (PPO)/polyamide 66（PA66） alloys. Mechanical and scanning electron microscopic characterizations indicated that the intermeshing corotating twinscrew extruder as a conventional mixing equipment was suitable for the preparation of PPO/PA66 alloys in comparison with the other two equipments. The intermeshing counterrotating twinscrew extruder was also an appropriate processing means for PPO/PA66 alloys in some cases. Nevertheless, Buss kneader was unsuitable for processing PPO/PA66 alloys.

Structure and Properties of Special Resin for Singlelayer Cast Film

2016, 30 (12): 13-17 ; DOI: 10.19491/j.issn.1001-9278.2016.12.003

Abstract ( 419 )

A comparative study was performed for the molecular structures and performance of two types of special polyethylene resins designed for singlelayer cast films. Although these two resins are produced through a Unipol gas phase method and had a melt flow rate of 3.5 g/10 min, one resin is domestically made and the other one is imported from ExxonMobil. The results indicated that the relative molecular weight and its distributions of the two resins were similar to each other. Moreover, these two resins also exhibit a similarity in sequence structure and distribution of comonomer in their macromolecules. However, there are differences in the composition distributions and crystallization behavior of the two resins, which resulted in higher impact toughness and tearing resistance but poor tensile and optical properties for the domestically made resin in comparison with the imported one.

Influence of Base Materials on Properties of Fireresistant Coiled Materials

yang-shousheng yang-shousheng

2016, 30 (12): 18-24 ; DOI: 10.19491/j.issn.1001-9278.2016.12.004

Abstract ( 586 )

In this work, a type of fireresistant coiled materials used as for steel structure protection was prepared by using lowdensity polyethylene (PE-LD), ethylenepropylenedienemonomer rubber (EPDM) and chlorinated polyethylene (CPE) as base materials. The influence of base materials on the performance of fireresistant coiled materials was investigated. The results indicated that the fireresistant coiled materials achieved better fire resistance, higher tensile strength and greater elongation at break when CPE was used as a base material, whereas they exhibited lower flexural strength and modulus when EPDM was used as a base material. When a compound of CPE and EPDM was used as base materials at a weight ratio of 6：4, the fireresistant coiled materials not only gained an expansion ratio of 22 and good fire resistance but also achieved much better mechanical properties in terms of tensile strength of 2.31 MPa, elongation at break of 855.47 %, flexural strength of 5.47 MPa and flexural modulus of 6.11 MPa. It is concluded that the compound of CPE and EPDM was more suitable as a based material for preparation of the fireresistant coiled materials due to the advantage of intumescent flame retardancy.

Blending Modification and Microbiological Degradation of P(3,4HB)/PHBV Blends

2016, 30 (12): 25-29 ; DOI: 10.19491/j.issn.1001-9278.2016.12.005

Abstract ( 536 )

Blends of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) ［P(3,4HB)］ and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were prepared by using a solvent mixing method, and their mechanical properties were investigated. Moreover, the blends were also characterized by differential scanning calorimetry and thermogravimetry analysis. Microbiological degradation behaviors of blend was studied by using a Pseudomonas mendocina DS04-T bacterium, and then scanning electron microscopy was conducted to characterize the microstructure of the test sheets after biodegradation. The results indicated that the blends exhibited optimal mechanical properties in tensile strength and elongation at break when the weight ratio of P(3,4HB) and PHBV was set at 80/20. A stable crystal structure was observed in the blends due to good interaction and miscibility between two phases when the loading of PHBV was less than 60 wt %. The degradation time of the blends was much shorter than that of pure P(3,4HB) with the aid of Pseudomonas mendocina DS04-T bacterium.

Preparation and Properties of Poly(vinyl chloride)/Halloysite Nanotube Composites

2016, 30 (12): 30-35 ; DOI: 10.19491/j.issn.1001-9278.2016.12.006

Abstract ( 445 )

Composites based on poly(vinyl chloride) (PVC) and halloysite nanotubes (HNTs) were prepared by a melt mixing method. Effect of HNTs content on morphologies and properties of composites was investigated by mechanical measurements, scanning electron microscopy and transmission electron microscopy, and effecting mechanism of HNTs toward PVC was analyzed. The results indicated that HNTs could generate a toughening effect on PVC, and PVC/HNTs composites exhibited an increase in storage modulus and glass transition temperature in comparison pure PVC. HNTs presented a good dispersibility in PVC matrix, and there was no agglomeration of HNTs observed with a variation of content of HNTs, which may be attributed to a good interfacial adhesion between PVC and HNTs according to an interface semiempirical parameters B of 4.35.

Study on Ethylene-vinyl Acetate Copolymer Toughed Polyacetal

2016, 30 (12): 35-40 ; DOI: 10.19491/j.issn.1001-9278.2016.12.007

Abstract ( 758 )

Polyacetal (POM)/ethylene-vinyl acetate copolymer（EVA）compounds were melt blended by a twinscrew extruder. Mechanical properties, crystallinity and morphologies of the compounds were investigated. The results indicated that notched impact strength of the compounds was improved effectively with addition of EVA and increased with the EVA content, but their flexural modulus and tensile strength decreased gradually. The presence of EVA influenced the crystallization behavior of POM and resulted in a decrease in crystallinity of POM. Transmission electron microscopic observation revealed a clear interface between the two phases, indicating poor compatibility between the two polymers. However, a wide particle-size distribution was observed for the dispersed phase, which may favor the toughening of POM.

Evaluation of Gelation Degree of Unplasticized Poly(vinyl chloride) by Torque Rheometer

2016, 30 (12): 41-46 ; DOI: 10.19491/j.issn.1001-9278.2016.12.008

Abstract ( 661 )

The rheological characteristics of unplasticized poly(vinyl chloride)（PVC-U）was evaluated by a torque rheometer. The resulting rheological torque curves indicated that PVC-U achieved a higher minimum torque with its gelation degree getting greater, thus, the difference between its maximum and minimum torques became smaller. On the basis of this relationship, an evaluation method was proposed for estimating the gelation degree of PVC-U.

3D Printing Molding Process for Large ABS/GF Products

2016, 30 (12): 47-51 ; DOI: 10.19491/j.issn.1001-9278.2016.12.009

Abstract ( 509 )

3Dprinting molding process of large-scale parts based on a composite of acrylonitrile-butadiene-styrene copolymer (ABS) with 20 wt % glass fibers was studied by constructing a large 3D-printing experiment platform. Effect of pressure on melt extrusion rate, extrudate diameter and mass flow rate was investigated at a rotation speed of 0 for metering screw, and meanwhile, effects of pressure and rotation speed of measuring screw on mass flow rate were also evaluated. In addition, the effects of printing speed, rotation speed of metering screw and cumulate height on the width of stacked monofilament were investigated. The results indicated that the mass flow rate, extrudate diameter and mass flow rate tended to increase with increasing pressure and rotation speed of metering screw. Furthermore, the width of stacked monofilament tended to decrease with increasing printing speed, to increase with increasing rotation speed of metering screw, and to decrease with increasing the cumulate height. Summarily, as long as the aforementioned processing parameters are controlled precisely, a good melt flow and solidification form can be obtained, and a highly precise form can be achieved for the large-scale 3D printing products.

Experimental Study on Residual Thickness of Pipes with Curved Sections Made by Waterassisted Coinjection Molding

2016, 30 (12): 52-57 ; DOI: 10.19491/j.issn.1001-9278.2016.12.010

Abstract ( 556 )

Pipes with curved sections were injection-molded by the water-assisted co-injection molding process (WACIM) on a lab-developed WACIM system, and their wall thickness was analyzed. The results indicated that, at the outer convex side, the total wall thickness and wall thickness of inner layer were much bigger for the curved pipes molded by the overflow WACIM (O-WACIM), but at the inner convex side, both of them were smaller for the curved pipes molded by the shortshot WACIM (S-WACIM). However, the average total wall thickness and the average wall thickness of inner layer for the curved pipes molded by S-WACIM were smaller than those by O-WACIM, and they became much smaller in the curved section of the pipes. At the outer convex side of the pipes, the total wall thickness and the wall thickness of inner layer increased with an increase of bending angle, but at the inner convex side, they tended to decrease.

CAE-based Optimization of Injection Molding Parameters for Thick-section Parts

2016, 30 (12): 58-62 ; DOI: 10.19491/j.issn.1001-9278.2016.12.011

Abstract ( 489 )

The injection molding process of a thick-section part was simulated by using a Moldflow software. On the base of an orthogonal experiment and the multiple evaluation indicators reflecting the shrinkage and warpage of the part, the influences on filling time, melt temperature, packing time, packing pressure and cooling time by mean value analysis and range analysis were investigated, and then these processing parameters were optimized by a comprehensive scoring method. The results indicated that the warpage and shrinkage could be reduced by improving the packing time and packing pressure. A series of optimum processing parameters were achieved as filling time of 2.5 s, melt temperature of 280 ℃, packing time of 130 s, packing pressure of 110 MPa and cooling time of 40 s. When being injection molded with such optimized processing parameters, the part presented a distinct decrease in quality looseness by 6.66 %, volume shrinkage by 7.90 %, plane error by 12.5 % and warpage by 20.83 %. The thick-section part exhibited an improvement in total quality due to the CAE-based optimization combined with the orthogonal experiment.

Analysis of Bullet Velocity for Textile Fabric Reinforced Composites under Ballistic Impact

2016, 30 (12): 63-69 ; DOI: 10.19491/j.issn.1001-9278.2016.12.012

Abstract ( 616 )

A ballistic impact model was established for textile fabric reinforced composites by using an ABAQUS software to analyze the residual velocity, variation of acceleration and energy loss when a bullet passed through the composites, in which the initial conditions for the incident bullet was set in accordance with the actual one. The results indicated that both the theoretic and experiment values for the residual velocity kept a linear relationship with its incident velocity. The higher the incident velocity, the greater the slope of plot of bullet velocity vs. time at the initial stage of incident bullet, and the greater was the absolute value of acceleration at peak. The calculated values obtained from the simulation of energy loss for the ballistic impact was in good agreement with experimental ones.

Influence of Processing Parameters on the Shrinkage of Asymmetric Thin Wall Plastic Parts Made by Two Cavity Injection Molding

2016, 30 (12): 70-74 ; DOI: 10.19491/j.issn.1001-9278.2016.12.013

Abstract ( 521 )

In order to reduce the shrinkage rate of plastic parts, the influence of process parameters on the shrinkage of plastic parts was studied by means of analysis of variance and orthogonal test. The results indicated that the plastic shrinkage obtained through the combination of optimal process parameters was 4.3117 %, Which was much smaller than the experimental one obtained from 25 times of orthogonal tests. In the case of acrylonitrile-butadiene-styrene resin, the effect of processing parameters on the shrinkage became significant in an order of injection time > melt temperature > holding time > mold temperature > cooling time > holding pressure.

Flame Retardant Effect of Two Kinds of Zinc Hydroxystannate on Poly (vinyl chloride)

2016, 30 (12): 75-80 ; DOI: 10.19491/j.issn.1001-9278.2016.12.014

Abstract ( 499 )

Amorphous and spherical zinc hydroxystannate (ZHS) particles with different particle sizes were prepared by using sodium stannate and zinc sulfate as raw materials. A comparative investigation was conducted on the flame-retardant and smoke-suppressant properties, tensile strength and thermal degradation properties of poly(vinyl chloride) (PVC) based compounds containing these two types of ZHS, and the dispersibility of ZHS particles in the PVC matrix was studied. The results indicated that, compared with amorphous ZHS particles, the spherical ones have more positive influences on the flame-retardancy, smoke-suppressant, tensile properties of PVC compounds at the same loading of ZHS. The incorporation of ZHS also improved the char yield of PVC at the end of thermal degradation and reduced the initial decomposition temperature and peak temperature at the first weight-loss stage. The amorphous ZHS exhibited a more significant decline in these two characteristic temperatures. In addition, the amorphous ZHS presented a better dispersibility and a tighter combination with PVC matrix than the spherical one.

Study of Cellulose Acetate Plasticized with Phthalate Free Plasticizers

2016, 30 (12): 81-85 ; DOI: 10.19491/j.issn.1001-9278.2016.12.015

Abstract ( 721 )

A comparative investigation was performed on the cellulose acetate (CA) plasticized with three eco-friendly plasticizers including polyethyleneglycol (PEG), the mixture of glyceryl triacetate and acetyl citric acid alkyl ester (GA) and the one with traditional diethyl phthalate (DEP). The results indicated that, when the loading of plasticizer was fixed at 30 phr, the CA compound with PEG exhibited lower strength, higher water absorption and lower melt flow rate than those with the other two. On the other hand, compounds with GA and DEP presented the same tensile strength, water absorption, tear strength and migration rate of the plasticizer, whereas its elongation at break increased by 58.7 % in comparison with DEP.

Implementation Progress and Analysis of ODS Phase-out in Foam Sectors in China

2016, 30 (12): 86-90 ; DOI: 10.19491/j.issn.1001-9278.2016.12.016

Abstract ( 624 )

The article introduced the implementation progress of ODS phaseout in foam sectors in China, and analyzed characteristics of the compliance mechanism of the Montreal Protocol as well as its influence on ODS phaseout in foam sectors. During the 13th Fiveyear Plan period, China will further enhance ODS management, and increasingly strengthen its efforts and support on the compliance tasks in order to ensure its achievement of phaseout targets as stipulated by the Montreal Protocol.

Study on Mechanical Properties of Recycled Polyoxymethylene/Modified Bamboo Fiber Composites

2016, 30 (12): 91-96 ; DOI: 10.19491/j.issn.1001-9278.2016.12.017

Abstract ( 725 )

An interfacial control for bamboo fibers (BF) with recycled polyoxymethylene (rePOM) was conducted by using NaOH, alkali and silanecoupling agent, alkali and isocyanate, respectively. Effects of modification method and BF content on mechanical properties of the re-POM/BF composites were investigated. The results indicated that this interfacial control could be well performed by the mixtures of NaOH with silanecoupling agent and with isocyanate. An increase of 13.38 % in flexure strength along with tensile strength of 50.36 MPa was achieved for composites containing 20 wt % of BF modified by the mixture of NaOH with 2 wt % isocyanate. On the other hand, the composite obtained an increase in flexure strength by 12.61 % as well as tensile strength of 46.87 MPa. It was concluded that the mixture of alkali with 2 wt % isocyanate could generate a much better modification effect on BF, and the composite containing 20 wt % BF achieved the optimum mechanical properties.

Impact of Wood Powder and Antioxidant on Waste High-density Polyethylene/Salix Composites

2016, 30 (12): 97-102 ; DOI: 10.19491/j.issn.1001-9278.2016.12.018

Abstract ( 434 )

Woodplastic composites (WPC) were prepared by compression molding of waste high-density polyethylene (PE-HD) with salix wood powders, and effects of wood powders and antioxidant on properties of WPS were investigated. The results indicated that, when the loading of salix wood powder was in the range of 0~70 wt %, the static bending intensity of WPC presented an increase at first and then tended to decrease, and so did the elasticity modulus and tensile strength. The salix wood powders reduced the thermal stability of WPC and led to a decrease in their initial decomposition temperatures. The presence of salix wood powders also resulted in an increase in storage and loss moduli of WPC but a decrease in their loss factors. Moreover, there was a shift of loss factor peak to a higher temperature for WPC. On the other hand, with addition of Antioxidant 1010 in the content range of 0~0.5 wt %, the static bending intensity, elasticity modulus and tensile strength of WPC also tended to increase at first and decrease afterwards. The storage and loss moduli of WPC exhibited relatively high values when 0.2 wt % and 0.3 wt % of Antioxidant 1010 was incorporated.

Design of Injection Moulds with Antecedent Pushing out in Sloping Inserts of Core Molds for Printer Shells

2016, 30 (12): 103-106 ; DOI: 10.19491/j.issn.1001-9278.2016.12.019

Abstract ( 536 )

This article analyzed the technological characteristic of a printer shell and introduced the structural design and operating process of the injection mould for this part. To fabricate such a mould, two side core-pulling mechanisms were adopted, and antecedent pushing-out was realized in the sloping insert of moving molds at the mold opening time by using wedge and sliding block. Fixed mould puller pins, stop drag-bars and pull-rod were used to open the mould sequentially. Such a mould structure was rational and safe in operation.