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2016, Volume 30 Issue 08 Publication date: 26 August 2016 Previous Issue Next Issue

Situation of Agricultural Films Dng the 12th Five-year Plan Period and Their Development Prospect during the 13th Five-year Plan Period in China

2016, 30 (08): 1-10 ; DOI: 10.19491/j.issn.1001-9278.2016.08.001

Abstract ( 737 )

Situation of agricultural films during the 12th Five-year Plan Period in China was summarized, including capacity and output, types and localization of agricultural films, as well as existing problems Development prospect of agricultural films during the 13th Five-year Plan Period was presented, including the guiding lines,basic principles,development targets and important films and technologies ,and so on.

Advances in Research of Plant Fiber Reinforced Polyhydroxyalkanoate Composites

2016, 30 (08): 11-16 ; DOI: 10.19491/j.issn.1001-9278.2016.08.002

Abstract ( 538 )

Four polyhydroxyalkanoate biodegradable plastics—poly(3hydroxybutyrate) (PHB), poly(3hydroxybutyratecohydroxyvalrate) (PHBV), poly(3hydroxybutyratecohydroxybutyrate) ［P(3,4)HB］, and poly(3hydroxybutyratecohydroxyhexanoate) (PHBHHx) were used as polymer matrix of plant fiber reinforced biological composites. The influence of modified plant fiber (wood fiber, hemp and straw fiber, etc.) and interface modified methods on mechanical properties, thermal stability, and crystallization of the composites was reviewed. The research and development of plant fiber reinforced biological degradable composites in the future were also predicted.

Shape Memory Effects of SBS/PELD Blends Crosslinked by Dicumyl Peroxide and Multifunctional Monomers

2016, 30 (08): 17-22 ; DOI: 10.19491/j.issn.1001-9278.2016.08.003

Abstract ( 506 )

A series of shape memory materials was fabricated by blending styrene butadiene copolymer (SBS) with low density polyethylene (PE-LD) and crosslinked by dicumyl peroxide (DCP) in the presence of multifunctional monomers. The degree of crosslinking，tensile strength，and elongation at break of the crosslinked blends were investigated. The results indicated that multifunctional monomers played an enhancing role in the chemical crosslinking of SBS/PE-LD blends and the crosslinked SBS/PE-LD blends exhibited an excellent shape memory behavior，the shape fixed ratio and the shape recovery ratio of the crosslinked SBS/PE-LD blends could be 100 %. With increasing content of multifunctional monomers，the degree of crosslinking of the blends increased.

Preparation and Properties of Amino-functionalized Polystyrene Microspheres for Carbon Dioxide Adsorption

2016, 30 (08): 23-28 ; DOI: 10.19491/j.issn.1001-9278.2016.08.004

Abstract ( 660 )

Polystyrene/poly(glycidyl methacrylate) (PS/PGMA) microspheres were first prepared by fine emulsion polymerization, the surface of which was subsequently aminofunctionalized via the reaction between epoxy groups on GMA and amines groups. Effect of the monomer ratio on the particle size and distribution of microspheres was investigated. The microspheres were characterized by DLS, SEM, IR, and elemental analysis. The particle size was uniform and controllable, with the smallest being 67 nm. The aminofunctionalized spheres were applied in CO2 adsorption. The CO2 adsorption capacity of ethylenediamine (EDA) modified microspheres reached 2.45 mmol/g.

Structure and Property Analysis of PE-mLLD

2016, 30 (08): 29-33 ; DOI: 10.19491/j.issn.1001-9278.2016.08.005

Abstract ( 556 )

Four kinds of metallocene linear low density polyethylene (PE-mLLD) and a regular linear low density polyethylene (PE-LLD) by Dushanzi Petrochemical Co. were studied, with their basic physical index, thermodynamic properties, cohesion state structure, relative molecular mass and its distribution, molecular chain structure and rheological properties being analyzed. Three PE-mLLD samples were copolymerized with hexane, which could be categorized as narrow and wide distributed ones. The former had a poor processability but better mechanical properties than PE-LLD; and the latter contained many branches so could be easily processed. The sample from DOW was copolymerized with octane, its molecular weight distribution was wide, both processing and mechanical properties were good.

Study on the Properties of Conductive Silicone Rubber Filled with Carbon Black/Aluminum Powder

2016, 30 (08): 34-38 ; DOI: 10.19491/j.issn.1001-9278.2016.08.006

Abstract ( 729 )

With carbon black and aluminum powder as conductive fillers, the conductive silicone rubber samples were prepared by solution blending. Effect of carbon black/aluminum powder on conductivity and piezo resistance of the silicone rubber was studied. It showed that the resistance of the silicone rubber decreased first and then increased with increasing aluminum powder content and constant carbon black content. When the filler content was constant, with increasing pressure, the piezo resistance decreased and tends to be stable. The studies showed that the conductivity of was best and the piezo resistive range was increased when the carbon black content was 30 % and aluminum powder content was 3 %.

Mechanical and Flame Retardancy Properties of Polypropylene/Holloysite Composites

2016, 30 (08): 39-42 ; DOI: 10.19491/j.issn.1001-9278.2016.08.007

Abstract ( 532 )

A series of polypropylene/holloysite (PP/HNTs) composites were prepared by melt blending, and their mechanical properties, interfacial and flame retardancy were characterized. The results showed that HNTs had synergistic effect with other additives on improving the flame retardancy of the composites. The limiting oxygen index of the composites reached 32 %, and vertical burning behavior with 2 % HNTs was UL 94 V-0 class, and impact strength, tensile and flexural strength were 5.4 kJ/m2, 36.5 MPa, and 41.4 MPa, respectively.

Antioxidant Properties of Hyperbranched Bridged Hindered Phenols in Polyethylene Resins

2016, 30 (08): 43-49 ; DOI: 10.19491/j.issn.1001-9278.2016.08.008

Abstract ( 587 )

Novel hyperbranch bridge hindered phenols (HBHP) were synthesized from β(3,5-diterbutyl-4-hydroxyphenyl) propionyl chloride and low generation hyperbranched macromolecule, and the products were characterized by FTIR and 1H-NMR. And the processing stability and thermal oxidative stability of HBHPs in two polyethylene resins were investigated. HBHP provided excellent processing stability and antioxidant property for polyethylene, and their antioxidant function was superior to that of antioxidant 1076. Moreover, the antioxidant function of HBHP in two polyethylene resins increased with increasing of the length of alkyl chain. The antioxidant properties of HBHP in PE-HD were slightly better than those in PE-LLD.

Preparation and Properties of Environmentally-friendly Food Cans Sealing Rings with Low Migration

2016, 30 (08): 50-54 ; DOI: 10.19491/j.issn.1001-9278.2016.08.009

Abstract ( 529 )

Sealing rings with low migration were prepared from PVC paste resin, Dinch and polyester plasticizers and other additives. Effect of the degree of polymerization of PVC, the content of foaming agent, processing temperature, and storage time on migration resistance of the sealing rings was studied. It showed that with increasing degree of polymerization of PVC, the capacity of plasticizer absorption became stronger, and the migration resistance of the sealing rings was improved. With increasing amount of blowing agent, foam cells of the sealing ring became larger and more popular and the plasticizer migration was increased. When the processing temperature was 195 ℃, the plasticizer migration was the minimum, higher or lower processing temperature would damage the degree of plasticizing. With increasing storage time, the resistance to migration was reduced.

Effect of Process Parameters on Ejected Molten Polymer Droplets

2016, 30 (08): 55-59 ; DOI: 10.19491/j.issn.1001-9278.2016.08.010

Abstract ( 450 )

A mechanical impact melt ejection device was introduced. Influence of screw speed (impact frequency), nozzle diameter, and nozzlesubstrate distance on the molten PP droplet injection molding was analyzed. Experimental results showed that only when the process parameters were precisely controlled, could one get uniform and tiny droplets of polymer melt，thus ensuring highprecision molding in 3D printing.

Molecular Simulation of Mixed Gas Diffusion in Packing Stage in Polymer Injection Molding Process

2016, 30 (08): 60-64 ; DOI: 10.19491/j.issn.1001-9278.2016.08.011

Abstract ( 420 )

A model was formulated that contained oxygen, nitrogen molecules and PMMA polymer chains. The diffusion of the mixed gas (oxygen and nitrogen) in PMMA was simulated at different temperatures or pressures. It was found that the diffusion coefficients of oxygen and nitrogen in PMMA increased with increasing temperature and pressure and finally reached a platform. The interaction between the two kinds of molecules during the diffusion was also discussed. Different kinds of molecules had a synergistic effect during the diffusion, the diffusion coefficient of the gas in the mixed gas system was greater than that in the pure gas system.

Research on Part Surface Quality Improvement of Microcellular Foaming Molding Process

2016, 30 (08): 65-69 ; DOI: 10.19491/j.issn.1001-9278.2016.08.012

Abstract ( 529 )

Firstly a dumbbell test model was established to research the relationship between process parameters and surface quality. Through Taguchi experimental design and signaltonoise ratio and analysis of variance methods, the effect of mold temperature, melt temperature, injection rate, filling quantity, and gas concentration on the surface quality was analyzed. The surface of the samples was characterized by scanning electron microscopy and roughness measuring instrument. Finally, the research conclusion was applied to the actual experiments, which showed that the optimal combination of parameters could be obtained from the analysis of signaltonoise ratio and variance and the surface roughness could be reduced.

Numerical Simulation and Experiment of the Influence of Delay Time on Gas Penetration in Gasassisted Injection Molding

2016, 30 (08): 70-74 ; DOI: 10.19491/j.issn.1001-9278.2016.08.013

Abstract ( 630 )

In this paper, the gas penetration behavior in gasassisted injection molding with different delay time is studied by physical experiment and full 3D numerical simulation In the end, the results are analyzed and discussed It was found that the delay time has greater impact on the key factors in determining the quality of products such as the gas penetration length, scale of gas finger and residual wall thickness.

Heat Stabilization of Mercaptans and Thiophenols on PVC—Progressive Change Law of Performance and Mechanism

2016, 30 (08): 75-78 ; DOI: 10.19491/j.issn.1001-9278.2016.08.014

Abstract ( 708 )

The heat stabilization of several mercaptans and thiophenols on PVC was determined by the oven discoloration method. It was found that their heat stabilizing capacity improved with increasing of the positive electricity of the α-C atom and decreasing of the strength of the S—C bond in the molecules. According to this finding it could be speculated that mercaptans and thiophenols stabilize PVC by electrophilic reaction with PVC using their α-C atom as the electrophilic centers. This meant that the traditional Frye and Horst’s theory of heat stabilization did not apply to mercaptans and thiophenols, and therefore, the exact mechanism of heat stabilization of heat stabilizers need to be clarified by further research.

Biodegradation Behavior of PLA/PBAT Blends

2016, 30 (08): 79-86 ; DOI: 10.19491/j.issn.1001-9278.2016.08.015

Abstract ( 954 )

In this study, blended film of poly(lactic acid) (PLA)/poly(butylene adipateco terephthalate) (PBAT) was prepared by a twinscrew extruder and a single screw extruder. The thermal, mechanical properties and microstructure had been investigated. The biodegradation rate of the blends under composting condition was measured, and the structure, element content, and thermomechanical behavior before and after degradation was characterized. It indicated that PLA/PBAT blend was an immiscible system, and the addition of PBAT improved the flexibility of PLA. It also found that, the biodegradation rate of neat PLA was greater than that of neat PBAT, and the biodegradation rate of PLA/PBAT blends was decreased with increasing PBAT content. Furthermore, the degradation products may accelerate the hydrolysis of PBAT at the beginning of degradation. At the earlier stage of degradation under composting condition, the long polymer chains of PLA, PBAT and their blends hydrolyzed to short chains without chemical structure change of the monomers. The degradation of neat PLA and PBAT initially occurred at amorphous phase, however the degradation of PLA/PBAT blends occurred at both amorphous and crystalline phases simultaneously. Moreover, the degradation of PLA chains in amorphous phase in blends was decreased affected by the addition of PBAT. The degradation of PLA/PBAT blends was mainly started with a hydrolysis.

Study of Two-component, Solvent-free Polyurethane Adhesives Prepared from Modified Plant-oil-based Polyols

2016, 30 (08): 87-92 ; DOI: 10.19491/j.issn.1001-9278.2016.08.016

Abstract ( 519 )

Castor oil (CO) and epoxidized soybean oil (ESBO) were used as plantoilbased polyols, based on which four kinds of wrapping polyurethane adhesives were prepared by using isophorone diisocyanate (IPDI), polyethylene glycol (PEG)400 or CO without solvent. TGA, DSC, tensile mechanical properties test, PE/OPP composite membrane peel strength test and shear strength test were carried out for the polyurethane adhesives film. It showed that the polyurethane adhesives prepared by PEG400 and plantoilbased polyols get the peel strength about 200 N/m with the best shear strength 4.9 N/mm^2; polyurethane adhesives prepared by all plant oil get the better thermal decomposition and water resistance properties.

Quality Control of PVC Pipes for Water Supply in America

2016, 30 (08): 93-97 ; DOI: 10.19491/j.issn.1001-9278.2016.08.018

Abstract ( 606 )

In the United States, poly(vinyl chloride) (PVC) pipes accounts for about 66 % of the total plastic pipes, and always are the largest amount used for water supply. This paper analysed the quality control in USA according to the American standards and certification systems from the aspects of raw material control, compound class, and the testing of the product. A comparison was also made between Chinese and USA standards for the quality inspection methods.

Rigidity Analysis of Clamping Systems in Twoplate Injection Molding Machines

2016, 30 (08): 98-102 ; DOI: 10.19491/j.issn.1001-9278.2016.08.019

Abstract ( 590 )

The mechanical and hydraulic rigidities of twoplaten clamping systems and their influence factors were studied. It was found that it was very important to take the integral effect of the two rigidities into account during the design of clamping systems. It was different for the mechanical characteristics during the clamping and injection process, and the irreversible resilience of the mold impacted the secondary stretch of the mechanism.