PENG Li-chao, CHAI Yun, LIU Yang, ZHANG Pu-yu
Abstract (
3019 )
Biodegradable polymer blends based on polylactide (PLA) were reviewed, including blends of enantiomeric polylactides, PLA/ aliphatic polyester, PLA/ natural polymers, PLA/ poly(ε-caprolactone), PLA/ poly (ethylene glycol), PLA/ poly(vinyl alcohol), and PLA/ poly(vinylpyrrolidone). Current research showed that with addition of other biodegradable polymers to PLA, the mechanical properties and flexibility could be improved, and the cost was lowered. The blends hold environmentally friendly characteristic and enlarge the application field of PLA materials in engineering plastics and packaging.
YING Zong-rong, LIU Hai-sheng, CHEN Ren-kang, ZHU Lei, CHEN Fan
Abstract (
3295 )
Polymer/graphite conductive nanocomposites constituted one of research hotspots. The preparation methods for polymer/graphite conductive nanocomposites can be categorized as three types: alkali metal-intercalation polymerization, expanded graphite in-situ polymerization, and expanded graphite blend-composite. There are also some indirect blending methods, including ultrasonic shattering, surface treating, additive pre-composite, and pre-coated masterbatch, etc. Moreover, the future research emphases in polymer/graphite conductive nanocomposites was proposed.
CUI Guang-jun, WANG Yang, LI Hai-dong
Abstract (
3431 )
The nonisothermal crystallization behavior of poly(ε-caprolactone) was studied by DSC and XRD, the crystallization kinetics was analyzed using Ozawa and Jeziorny equations. The obtained Avrami index n is about 4, which demonstrates a three-dimensional spherulite growth on homogengous nuclei. Secondary crystallization process was observed when the relative crystallinity was 98 %, which was affected by the degree of supercooling.
CHEN Hong-liang, LI Si-de, GAO Li, MAO Li-xin
Abstract (
92 )
The rheological behavior ofpolypropylene/poly(ethylene-Octene-1)blends were investigated by means of Advanced Rheology Expansion System(ARES).The results of dynamic rheological tests indicated that the structure of PPand content of POE have obvious effect on the shear rheological bebay-ior of PP/POE blends.With the increase of POE content,the increase degree of the storage modulus and the shear viscosity of PP1/POE blends are less than those ofPP2/POEblendsThe above two blend systems showed greater increase in their storage modulus and the shear viscosity at POE content of twenty to thirty percent and ten to twenty percent respectively when brittle-ductile transition happened. Interfacial slip existed between PP and POE, which was greatly influenced by the compatibility of PF and POE, and the interfacial slip between PP1 and POE was more obvious than that between PP2 and POE.
WANG Wen-xuan, SHI Sheng-yong, YAN Chang-hao, WU De-feng, LU Ping, ZHANG Ming
Abstract (
3018 )
Poly(acylene ether nitriles) (PEN)/polyamide6(PA6) blends were prepared via melt mixing. The structures and crystallization behavior of the blends were characterized using SEM, DSC, and XRD. The mechanical and thermal properties were determined using EUTM and STA. It was found that PEN and PA6 were fairly compatible. Upon adding PA6, the processablity of PEN was improved. The tensile strength of the blends was 34 % higher than neat PEN.
LIU Jun, GU Lin, ZHAO Dian, WANG Jing-wu
Abstract (
2367 )
Influence of the content of PET, properties of matrix, and prosessing temperature on the mechanical and rheological behavior of PP/PET/MFIAA/HET composites was studied. With PET content increased, the number and fine degree of PET micro-fibril increased, which resulted in higher rigidity of the composite but lower toughness. Using PP having a high melt flow rate as the matrix was very beneficial to maintain the microfibril morphology of in situ fiberized composite sample. When using a PP matrix with melt flow rate of 16.2 g/10min, the notched Izod impact strength, tensile yield strength, and flexural modulus of PP/PET/MFIAA/HET with the matrix were 3.49, 0.99, and 1.73 times, respectively, those of neat PP. Effected by both melt-flowability and morphology of the disperse phase, the optimum prosessing temperature for PP/PET/MFIAA/HET should be （200±10）℃. PET microfibril constituted the main reason of the composite melt flow resistance, increasing the content of PET microfibril, the melt-flowability of PP/PET/MFIAA/HET falls rapidly.
ZHANG Qing-lan, HAO Yu-ying
Abstract (
3423 )
A kinetic study was performed on the crystallization of polyoxymethylene (POM) and POM /thermoplastic polyurethane (TPU) blends by means of differential scanning calorimetry at various cooling rates. Several theoretical models were applied to analyze the process. It showed that Jeziorny and Mo’s treatment described well the non-isothermal crystallization of POM and POM / TPU blends. The Avrami exponent n of POM/TPU blend is slightly smaller than that of POM. The values of half-time t1/2 and Zc showed that the crystallization rate increased with increasing cooling rates for both POM and POM/TPU blends, with the crystallization rate of POM/TPU blend being lower than that of neat POM. The activation energies were estimated by Kissinger method to be 513.5 and 390.5 kJ/mol for neat POM and POM/TPU blends, respectively.
BAO Chong-long, ZHU Geng-yu, CHEN Xue-ping, PU Qun, YE Ji-hua
Abstract (
1919 )
The crystallization behavior of PP/CaCO3 composites were investigated by means of differential scanning calorimeter (DSC) and polarized light microscope (PLM). DSC data showed that CaCO3 could serve as a nucleating agent, resulting in an enhancement of the overall crystallization rate. The crystal morphology of PP/CaCO3 composite was observed by polarized light microscope (PLM). A constant spherulite growth rate was observed at given isothermal crystallization temperature.
WANG Ping-ping, LU Ai, CHEN Xiao-yuan, WANG Gang, ZHANG Qing
Abstract (
3114 )
The effect of polyamide 66（PA66）on the tribological properties of glass fiber(GF)-reinforced polyphenylene sulfide(PPS) composites was studied. The inclusion of PA66 decreased the friction coefficients of PPS composites. When PA66 content was 40 wt%, the wear rate of the composites decreased from 13.60 to 5.24 mm3. The morphology of wear surface was investigated using SEM. It revealed that wear mechanisms of composites transformed from abrasive into adhesive wear with PA66 introduced. PA66 formed a non-uniform and discontinuous adhesive transfer film on steel counterface, while PPS did not. The maximum of the tangent of phase shift (tan δ) and storage modulus(E’) could be related with friction coefficients. The higher the (tan δ) maximum and E’, the smaller the friction coefficient smaller.
HE He-zhi, FU Jin-xiu, CHEN Zhe, FANG Wang-lai
Abstract (
1999 )
Wollastonite filled PP was studied in this work. The mechanical properties and SEM morphology of PP/Wollastonite blends were determined after being extruded by a dynamic tri-screw extruder. The effect of different dynamic parameters on the mechanical properties and the section microstructure were investigated. Compared with those based on steady condition, impact strength, tension strength, elongation ratio at break, and flex strength of the samples improved remarkably under dynamic working condition，the maximum increments being 10.7 %，10.2 %，51.3 %, and 18.6 %, respectively. Under the dynamic condition of f=10 Hz and A=105μm, the dispersion of wollastonite was improved, the particle size became smaller and more uniform, as revealed by SEM analysis.
ZHU Tie-li, SHENG Zhan-hui, LIU Yong-yun, WANG Min-jie
Abstract (
3097 )
By use of visualization equipments, photos of in-mold shrinkage were taken while the injection-molded plastic parts were in the mold for 24 h. By image processing of the photos, including edge extraction, beeline fit, and intersection calculation, positions of sign spots for the mold cavity and the part were determined. By a radial line from a sign spot on the cavity to the corresponding sign spot on the part, the shrinking direction of the sign spot on the part was obtained. From the experimental data concerning shrinkage directions, it was found that the points of part shrink were directed towards a region between the part’s centroid and the gate, and thus were determined by the positions of both centroid and gate.
LIU Yi, YIN Su-feng, FENG Yang, ZHANG Zu-jun, RUAN Feng
Abstract (
3033 )
In order to eliminate the weld lines on the plastic injection molded parts，the morphology of weld lines and the mechanism of removing weld lines by using sequential injection molding have been analyzed. Sequential injection molding was simulated based on the FEM model by means of software Moldflow. It showed that the delay time of second valve gate controlled the position and length of the weld-line. By using sequential injection molding, the weld lines on the molded parts were essentially eliminated.
ZHAO Jian
Abstract (
2822 )
In this paper, CAE and Taguchi DOE(design of experiment) technique were combined to investigate the influence of process conditions on the warpage of injection molded parts. Experiments on L16(215) orthogonal array with interaction of factors and L9(34) orthogonal array were carried out to minimize the warpage of injection-molded parts. For the factors selected in the main experiments, holding pressure and melt temperature were found to be the principal factors affecting the warpage of the injection molded parts. Under the optimum factor levels, the warpage of injection molded parts was decreased by 34.23 %.
HU Guang-hong, XU Xiao-ming, DU Yan-li, CUI Zhen-shan
Abstract (
3108 )
An aspheric plastic optical lens is studied by simulation experiment technology and Taguchi experimental method. Through the analysis of S/N ratio and ANOVA methods, the effect of various process parameters on the volumetric shrinkage was investigated. The results showed that the process parameters of effect significance on shrinkage were packing pressure, gate size, and packing time. It also revealed that the interaction between packing pressure and gate size was an important factors to affect the volumetric shrinkage of aspheric lens. Based on the analysis results, the optimized process parameters combination was obtained to reduce the part shrinkage.
LIU Dong-lei, XIN Yong
Abstract (
3037 )
Compared with the traditional injection molding technology, rapid heat cycling molding (RHCM) can remarkably improve the replication capability of polymer melt to cavity, eliminate some potential molding defects and increase rigidity and strength of the part. The process parameters optimization of a front shell of LCD television manufactured by RHCM technology was investigated by coupling with orthogonal experiment, CA analysis and data processing technology. The most important process parameters influencing each main quality index were determined based on analysis of variance (ANOVA) method firstly. Then the more optimum parameter set were found based on range analysis and synthetical balance analysis technology. The case results showed that the method was feasible and effective on processing quality optimization of high-gloss surface plastic part.
KUANG Tang-qing, LI Shu-zhen, HUANG Chuang-ye
Abstract (
2412 )
A two-component injection mold with 16 cavities for it was designed for the molding of a two-color toothbrush handle, in which the head part was made of a single material while the handle was decorated with a soft and colorful material. A two-component injection molding machine with rotary shaft was adopted. The structure and working process of the mold were introduced in detail. Moldflow was used to the design resulting in a balanced runner system. The design points of its hot-runner plates was explained.
TANG Er-jun
Abstract (
3244 )
ZnO nanoparticles were in-situ grafted with PMMA from the surface and used as a modifier for PVC. Such ZnO nanoparticles were homogeneously dispersed in the PVC matrix. Filled with PMMA grafted ZnO nanoparticles, PVC composites possessed a tensile strength of 78 MPa , which was 35% higher than that based on untreated ZnO; and an impact strength 13.6 kJ•m-2, twice as untreated case. In addition, PMMA grafted ZnO nanoparticles imparted PVC a perfect UV-shielding property.
CHAI Xi-juan, LIAO Ya-long, SUN Ke-wei
Abstract (
3087 )
The composite of second-handed-fiber and waste particle reinforced post-consumer mulch films was prepared via melt mixing. A compatibilizer (PE-g-MA) and microwave irradiation were employed to improve the mechanical performance and crystallization behavior of the composite. The compatibilizer and microwave irradiation caused the crystallization peak temperature of the composite reduced by 1.3 ℃ and 0.8 ℃ , and the crystallinity increased by 0.3 % and 2.49 %, respectively, compared with neat composite. The compatibilizer made the crystallization rate reduce, and microwave irradiation made the crystallization rate enhanced.
REN Shi-xiong, LI Jin-liang, LU Tao, WANG Kui-sheng
Abstract (
2971 )
Three-dimensional models of heat transfer for a die with seven different geometrical dimensions of die holes and three different geometrical dimensions of channels of conduct oil of pelletizing under water were created and solved by numercial simulation to obtain temperature field inside the die. The temperature field of the die under the conditions of different temperatures of cooling water, different coefficients of heat transfer of heating oil, different materials were also calculated. Due to the cooling effect of water, the temperature of the surface of pelletizing zone of the die was relatively low in the direction along the thickness; due to the heating effect of heating oil and polymer, the temperature of the deep zone of pelletizing zone of the die was gradually increased. Combined effects of heating of oil and cooling of water led to greater gradient of temperature close to the pelletizing surface, in the range of 0 z  10mm. Through analysis, it was found that the geometrical dimensions of the die hole did not affect the temperature field of the die; while the form of channels of heating oil, the temperature of cooling water, heat transfer coefficient of heating oil, and the material of the die did. These results provided a reliable theoretical basis for the structural design of die, determination of the boundary conditions, and the choice of materials.
LI Hao
Abstract (
2522 )
This article introduced the process procedure of 2-layer co-extrusion blown film technology of TPU/PE and the specific requirement of TPU on screw, die, dual-lip air ring, haul-off and winding. As a conclusion, to quickly extrude and haul-off TPU, one needs to use not only a bimetal and mixing screw of φ75×30, compression ratio of 2.2 to process TPU and a barrier screw of φ75×30, compressio ratio of 1.8 to process PE, but also a 2-layer co-extrusion central-fed die with a lip diameter of 500 mm. This co-extrusion technology can overcome the low efficiency in processing of TPU when using normal screw. The study indicated that TPU and PE from M2B-1700QA blown film line in suitable configuration showed good quality in plasticizing, with a maximum output of 250 kg/h, and a thickness of TPU film of 0.015～0.1 mm, while the MD and TD tolerance can be controlled within ±8 %.
