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2010, Volume 24 Issue 05 Publication date: 26 May 2010 Previous Issue Next Issue

The Treating and Exploitation Development of Plastic Additives in Law Situation

2010, 24 (05): 1-5 ; DOI: 10.19491/j.issn.1001-9278.2010.05.001

Abstract ( 2376 )

Some abroad codes about environmental protecting and health care were introduced in this paper, and their impact on plastic additive industry were analyzed, especially on plasticizers, flame retardants, and heat stabilizers. The measures that domestic manufacturers should adopt to deal with these codes were analyzed. It was pointed out that more attentions should be paid on independent innovation of plastic additives.

Research Progress on the Compatibility Improvement of Polypropylene Flame-retarded by Intumescent Flame Retardants

2010, 24 (05): 6-13 ; DOI: 10.19491/j.issn.1001-9278.2010.05.002

Abstract ( 2469 )

The recent progress on the compatibility between polypropylene（PP）and intumescent flame retardant was reviewed. The compatibility could be improved by using charring agent, using coupling agent, micro-encapsulation, grafting modification, latex blending , so on. PP grafted with flame retardant monomers, synthesizing the PP compatible polymer containing the carbon source, gas source and acid source of intumescent flame retardant were the future trend.

Recent Development of Polypyrrole/Inorganic Particle Nanocomposites

2010, 24 (05): 14-19 ; DOI: 10.19491/j.issn.1001-9278.2010.05.003

Abstract ( 2451 )

The preparation and mechanical, optics, electric, magnetic properties of polypyrrole（PPy）/inorganic particle nanocomposites were reviewed. The inorganic particle included inorganic magnetic particle，metal oxide，and inorganic carbons（carbon black，carbon nanotube，nano-graphite sheet）. The present research and applications of the nanocomposites in the fields of electromagnetic shielding, stealth materials, antistatic materials, conductive polymer capacitor, secondary battery, and chemical sensor were introduced．

Influence of Solid-phase Polycondensation on Thermal and Crystallization Properties of Polyester Chips

2010, 24 (05): 20-22 ; DOI: 10.19491/j.issn.1001-9278.2010.05.004

Abstract ( 2257 )

The thermal and crystallization properties of ordinary polyester (PET I) and solid-phase polycondensation thickened polyester chips (PET II) were analyzed by DSC and thermal gravimetric analysis. On the first heating of DSC, no crystallization endothermic peak was observed on PET II, indicative that the solid-phase polycondensation not only increased the molecular weight, but also completed the crystallization. The melting point of PET II increased. The crystallinity of PET II was lower, the size of PET II was smaller, the crystallization rate of PET II was smaller, compared with PET I. The thermal stability of PET II was better than PET I.

Structure and properties of metallocene linear low density polyethylene resin

2010, 24 (05): 23-27 ; DOI: 10.19491/j.issn.1001-9278.2010.05.005

Abstract ( 2372 )

The molecular weight and molecular weight distribution, branch degree, basic properties and rheological behavior of homemade and imported metallocene linear low density polyethylene resin(mLLDPE) were investigated contrastively. Results were found that homemade mLLDPE has broader molecular weight distribution and higher branch degree, so is easier to process compared with imported mLLDPE. The structure of mLLDPE can be analyzed through several rheological parameters, such as flow activation energy, shear thining index, relaxation spectrum index. In addition, their film properties were measured. Result was that film produced by homemade mLLDPE resin have better mechanical properties and worse appearance due to more fisheyes.

Research on the Surface Modification Mechanism of Pary(monochloro-p-xylylene) Films Modified by Sodium-naphthalene Complex

GAO Liude

2010, 24 (05): 28-33 ; DOI: 10.19491/j.issn.1001-9278.2010.05.006

Abstract ( 2131 )

Poly(monochloro-p-xylylene) was surface modified using sodium-naphthalene complex, the surface free energy of poly(monochloro-p-xylylene) was measured by the contact angles. The structure and the thermal stability of poly(monochloro-p-xylylene) were characterized by X-ray diffraction(XRD), thermogravimetry(TG), and fourier transform infrared spectroscopy(FTIR). After the modification, the surface free energy and shearing strength increased from 28.64 mJ/m2 to 41.48 mJ/m2 and from 150.5 kPa to 219.5 kPa, respectively. The increasing of the surface energy was mainly due to the reduction of the chlorobenzene.

Ring-opening Polymerization of Lactide in the Presence of Natural Amino Acids

2010, 24 (05): 34-38 ; DOI: 10.19491/j.issn.1001-9278.2010.05.008

Abstract ( 2155 )

The ring opening polymerization (ROP) of lactide in presence of amino acid was investigated. Effects of amino acid concentration, pH value, and reaction condition on the molecular weight of the polymer were discussed. For the ROP of D，L- lactide , the molecular weight of polymer increased with increasing basicity of amino acid. Under the condition of 150 °C for 48 h, when molar ratio of D，L-LA/L-lysine]=50/1, polymeric product with weight-average molecular weight of 12800 g/mol and polydispersity of / =2.11 was obtained. In the ROP of D, D- lactide and L, L- lactide, the racemization of the polymer increased with increasing basicity of amino acid.

Influence of Polymer Constitution on the Relationships Between Interfacial Tension and Molecular Weight

2010, 24 (05): 39-42 ; DOI: 10.19491/j.issn.1001-9278.2010.05.009

Abstract ( 1727 )

The interfacial tensions between polymers with different chemistry and/or molecular weight were measured using a polymer melt suspending drop instrument. The dependence of interfacial tension on structure and molecular weight were formulated. A novel equation was derived to describe such relationship which was proven more appropriate than traditional ones.

Optimized Preparation of Fiber/Resin Thermoplastics Composites for Dental Endodontic Posts

Jiang HU Huiming HE Yuhong LIU Yaping ZHENG

2010, 24 (05): 43-47 ; DOI: 10.19491/j.issn.1001-9278.2010.05.010

Abstract ( 2247 )

A new type of fiber-reinforced thermoplastic composite for dental endodontic post was prepared, in which a blend of poly（bisphenol A glycidyl dimethacrylate）/poly（methyl methacrylate） (PBGD/PMMA) was used as the matrix and glass fiber as reinforcer. The composite was characterized using glass transition temperature determination, SEM observation, and three-point bending test. The optimal preparation process was as follows: 74.1 wt % of glass fiber was impregnated with a mixture of monomers (BGD/MMA=80/20w), after a pre-polymerization at 80℃ for 2 h, the prepreg was pultruded at 1.0 cm/min and subsequently photopolymerized for 60 s. Thus obtained composite gave rise to a bending strength of 648.01 MPa and a bending modulus of 33.12 GPa, which was close to those of dentin.

Effects of Temperature and End-capped Additive Maleic Anhydride on the Viscosity-average Molecular Weight of Poly(propylene carbonate)

CHEN You-Ye

2010, 24 (05): 48-50 ; DOI: 10.19491/j.issn.1001-9278.2010.05.011

Abstract ( 2161 )

Effects of processing temperatures and loading of maleic anhydride (MAH) on the viscosity-average molecular weight of poly(propylene carbonate) (PPC) were investigated. When the temperature was above 120 ℃, the viscosity-average molecular weight decreased obviously, and the hither the temperature, the lower the viscosity-average molecular weight . A small quantity of MAH had obviously effect on the end-capping of PPC, at the same processing temperature, the effect on the end-capping increased with increasing content of MAH. However, the loading of MAH should below 1 wt%.

Nonisothermal Crystallization Behaviors and Crystal Morphology of PP/Nano-TiO₂ Composites

2010, 24 (05): 51-58 ; DOI: 10.19491/j.issn.1001-9278.2010.05.012

Abstract ( 2055 )

The polypropylene(PP)/nano-TiO2 composites were prepared via melt mixing. The dispersion of nano-TiO2, spherulitic morphology, and nonisothermal crystallization behavior of PP were studied using transmission electron microscopy (TEM), polarized optical microscope (POM) ，differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD). Results showed that nano-TiO2 dispersed uniformly in the nanoscale in PP. The spherulites in PP/nano-TiO2 composite was smaller than that in neat PP. With increasing content of nano-TiO2 , the size of spherulites decreased firstly and then increased. When the content of nano-TiO2 was 2 %, the spherulites of PP/nano-TiO2 composite was the smallest. The addition of nano-TiO2 accelerated the crystallization rate of PP. Nano-TiO2 promoted the formation of β crystals , when the content of nano-TiO2 was 1 %, the content of β crystal in the composite reached 25.2 %.

Properties of Color Masterbatch Containing High Melt Flow Rate PE-LLD in Different Contents of Pigment

qiao bo

2010, 24 (05): 59-62 ; DOI: 10.19491/j.issn.1001-9278.2010.05.013

Abstract ( 2175 )

A noval blue color masterbatch was prepared using a blend of PE-LD and high melt flow rate PE-LLD as the matrix containing no dispersant. The rheological, coloring and dispersion properties of the masterbatch were investigated, which was compared with the traditional masterbatch containing a low molecular weight polyethylene wax as a dispersant. It was found that the PE-LLD/PE-LD matrix with no dispersant could bear up to 30 % of blue pigment keeping good mechanical and coloring, and processing properties. However, when the content of pigment was 40 % or higher, neither novel nor traditional masterbatch could maintain a satisfactory performance.

Rheological Behavior of PE-LLD/SEBS-g-MAH/POE-g-MAH Blends

LUO Yongchun Hao ZHONG Xu XIONG Fanghong GONG

2010, 24 (05): 63-67 ; DOI: 10.19491/j.issn.1001-9278.2010.05.014

Abstract ( 2545 )

POE and SEBS was melt grafted with MAH in a twin-screw extruder separately, and introduced into PE-LLD forming binary blends PE-LLD/SEBS-g-MAH and ternary blends PE-LLD/POE-g-MAH/SEBS-g-MAH in a internal mixer. The rheological property of the blends was studied using a capillary rheometer. The ternary blend was found a typical pseudo-plastic melt. The apparent viscosity increased with increasing content of SEBS-g-MAH, and the influence of POE-g-MAH on the apparent viscosity of the blends was negligible.

Predicting Model for Bubble Morphology of PP/CaCO₃ Foaming Composites

2010, 24 (05): 68-73 ; DOI: 10.19491/j.issn.1001-9278.2010.05.016

Abstract ( 1984 )

Taking CO2 as a foaming agent, PP/CaCO3 composite was foamed in a single screw extruder. Orthogonal method was used to design the experiment and DOE software was used to count the data. The bubble morphology on the longitudinal surface was analyzed. The impact of the processing parameters on the bubble morphology was found, and the model of average diameter, surface density, deformation, and tendency angle were solved by Design-Expert software and compared with actual experimental data. When screw speed was 42~52 r/min, die temperature was 170 ℃, melt temperature was 180~189 ℃, and content of CaCO3 was 6.67 ％~ 7.9 ％，the foamed PP/CaCO3 composite showed the best bubble morphology.

Structure Modification of Injection Molded Plastics Parts with Uneven Thickness Based on CAE

2010, 24 (05): 74-77 ; DOI: 10.19491/j.issn.1001-9278.2010.05.017

Abstract ( 2062 )

The molding process of Toyota logo was analyzed using computer aided engineering(CAE), and the reasons for the appearance of sink mark and warpage were studied. To resolve the molding quality defects, the location of gating system and the wall thickness were adjusted. It was found that it did not work in changing the location of gating system, whereas a reduction of wall thickness was effective. When the central thickness was decreased to 3.6 mm, the maximum sink index decreased from 4.493 % to 3.886 %, the changing of sink index was more smoothly, and the value of warpage decreased from 0.4816 mm to 0.2414 mm.

Application of Moldflow Software in Warpage Optimization of Injection Molded Parts

2010, 24 (05): 78-80 ; DOI: 10.19491/j.issn.1001-9278.2010.05.018

Abstract ( 2604 )

Taking the buckle of automobile as an example, the injection molding was simulated using Moldflow software. Through analyzing the effects of materials kinds, melt temperature, and mold temperature, the best gate location and the optimized parameters were obtained. When PP(PP-7553) was used, the melt temperature was 220 ℃, and the mold temperature was 40 ℃, the minimum warp was obtained as 0.1519 mm.

Research on Polypropylene Composites Fire-retarded and Reinforced by APP/MCA

Guozhi Xu

2010, 24 (05): 81-84 ; DOI: 10.19491/j.issn.1001-9278.2010.05.019

Abstract ( 2259 )

Halogen-free flame-retarded PP composites were prepared by mixing polypropylene(PP) with melamine cyanurate(MCA) and ammonium polyphosphate（APP）. The flame-retarding property, thermo property, and mechanical property were characterized using limited oxygen index, thermo gravimetric analyzer, scanning electron microscope, and electronic tensile testing machine. The synergic flame-retarding effect of APP/MCA and its effect on the mechanical properties of PP were discussed. It was found that when the content of APP/MCA was 25 phr, the limited oxygen index and the mechanical properties of PP composites increased firstly and then decreased with increasing content of MCA. When the content of MCA in APP/MCA was 30 % , the limited oxygen index of the composite reached the highest value of 24.2 %, and its tensile strength increased 50 %, its breaking strength and yield strength also increased more than 10 %, compared with the composite flame-retarded by 25 phr APP.

Influence of Calcium Carbonate on Viscosity and Stability of PVC Plastisols

XU Guo-Min

2010, 24 (05): 85-88 ; DOI: 10.19491/j.issn.1001-9278.2010.05.020

Abstract ( 2192 )

The effect of particle size, content and morphology of calcium on the viscosity and stability of PVC plastisols were systemic investigated by vibrating viscometer. Results indicated that the plastisols prepared by 4.5 um calcium showed the highest viscosity and the worst stability. When maintaining the content of PVC resin at 100 phr, the PVC plastisols showed higher viscosity and worse stability with increasing the content of calcium. However, the PVC plastisols showed lower viscosity and better stability with increasing the content of calcium when maintaining the content of PVC and CaCO3 gross powder at 100 phr. The plastisols prepared by CaCO3 with diamond morphology showed lower viscosity, but the plastisols prepared by CaCO3 with batt morphology showed higher viscosity and the worst stability.

Determination of Contents of Starch in Starch-based Plastics by Thermogravimetry

2010, 24 (05): 89-93 ; DOI: 10.19491/j.issn.1001-9278.2010.05.021

Abstract ( 1946 )

Thermogravimetry(TG) was used to determine the content of starch in starch based plastics. The respective characteristic temperatures and mass loss under that temperatures in TG curves were determined. It was found that the characteristic temperatures of starch and resin were different, the mass loss of each component were relatively independent in starch based plastics, and the mass loss in starch-based plastics was the same as each single component. So the content of starch in starch based plastics could be calculated by proportional method through mass loss rate of pure starch. Results showed that the relative error was less than 10 % when the content of starch was more than 10 %.

Effects of Packing Controlled by Cavity Temperature on the Uniformity of Parts' Mass

Ting Wu

2010, 24 (05): 94-96 ; DOI: 10.19491/j.issn.1001-9278.2010.05.022

Abstract ( 2362 )

The effect of two packing modes, constant pressure and pressure-temperature control (PT control) on the accuracy of part's weight were studied under three filling-to-packing switchover modes, transfer controlled by injection time, screw position, and cavity pressure. In PT control, the holding pressure was decided by cavity temperature. It showed that the PT holding mode resulted a better part surface quality and uniform part weight than traditional methods. When the switchover mode of cavity pressure and PT control were used, the accuracy of part's weight was the best, which reach 0.0665 %.

Ejection System Design of Two-shot Inverse Moulds of Mobile Phones' Cases

Yong-Quan Zhou

2010, 24 (05): 97-100 ; DOI: 10.19491/j.issn.1001-9278.2010.05.023

Abstract ( 2256 )

A two-shot inverse mould design of mobile phone's case was developed, which was aimed at both pre-clamping system of 1st shot mould and ejection system mounted in stationary half of 2nd shot mould. Both gate mark and ejecting mark were avoided through a process platform. The demolding force of the creative friction locker was calculated against part's shrinkage .The moldflow simulation of the two-shot injection was made and reviewed. The inverse mould had overcome the defect of gas spraying mark emerged in normal sequence of two-shots injection and made the mass molding stable in high quality.