聚乳酸/线型低密度聚乙烯/乙烯-丙烯酸甲酯-甲基丙烯酸缩水甘油酯共混物的相态结构

以乙烯-丙烯酸甲酯-甲基丙烯酸缩水甘油酯共聚物(EMAG)为增容剂,制备了聚乳酸(PLA)/线型低密度聚乙烯(LLDPE)/EMAG的共混物。采用SEM,DSC,WAXD等手段对PLA/LLDPE/EMAG共混物进行了表征。表征结果显示,共混物中的EMAG起到了增容作用,使PLA/LLDPE/EMAG共混物的结晶能力减弱,分散相LLDPE在基体PLA中的粒径明显减小。Harkin’s铺展系数法计算结果表明,EMAG可在LLDPE中扩散并完全包覆LLDPE。实验结果表明,PLA/LLDPE/EMAG共混物的伸长率和冲击强度均随EMAG含量的增加而提高,m(PLA)∶m(LLDPE)∶m(EMAG)=81∶9∶10时的PLA/LLDPE/EMAG共混物的伸长率可达227%,冲击强度可达32.0 kJ/m2,并能保持较高的强度和刚性。     

耐温耐盐吸水性材料三元共聚物的合成与评价

以丙烯酸(AA)、丙烯酰胺(AM)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)单体为原料,采用水溶液聚合方法合成了三元共聚物吸水材料。考察了合成条件对共聚物吸液率的影响,确定了最佳合成配方,即AMPS：AA：AM摩尔比为1：2：7,交联剂用量0．01％,引发剂用量0．1％,溶液pH为10。评价了该共聚物在不同介质中的吸液率和抗温抗盐性,结果表明,在160g／L高矿化度盐水中吸液48h,吸液率达57g／g;90℃高温老化14d后吸液率无变化;在220g／L盐水中吸液率也无明显变化,说明此三元共聚物具有良好的吸液率和抗温抗盐性能。     

等规聚丙烯及其共混复合体系的辐射交联

本文研究了等规聚丙烯(i-PP)及其共混复合体系(PP/HDPE,PP/EPDM)辐射交联凝胶生成动力学。对于半结晶结构的i-PP,辐射交联的溶胶分数s随辐照剂量R的变化,符合裂解度正比于辐照剂量R的β次方的假定(β是与高聚物结构相关的参数),即 R(s+s~(1/2))与R~β具有很好的线性关系。对于i-PP共混体系,利于扫描电子显微镜和动态力学粘弹谱仪研究了其相结构特征和组分间的相互作用。结果表明,在一定剂量范围内共混体系的R~β可以修正为:R~β=∑X_iR~(βi)(X_i,β_f分别为共混物中第i组分的重量分数和β值)。用修正后的R~β处理PP/HDPE,PP/EPDM共混体系的凝胶生成数据,结果R(s+s~(1/2))司与R~β之间都具有很好的线性关系。     

核辐射技术及其在材料科学领域的应用

核辐射技术在材料科学领域得到了广泛的应用,利用辐射技术对无机材料、高分子材料进行改性和加工已成为一支新兴的高技术产业.综述了辐射技术在材料的改性和加工领域的应用研究进展,并详细介绍该单位在采用反应堆辐照技术研制碳化硅(SiC)陶瓷纤维、辐射交联法制备三元乙丙橡胶(EPDM)密封材料、辐射接枝合成偕胺肟型螯合树脂等方面开展的工作.     

Toughening effect of EPDM-graft-methyl methacrylate and styrene (EPDM-g-MMA-St) on methyl methacrylate-styrene copolymer (MS resin)

EPDM-graft-methyl methacrylate and styrene (EPDM-g-MMA-St) was synthesized by solution graft copolymerization of methyl methacrylate (MMA) and styrene(St) onto ethylene-proplene-diene terpolymer (EPDM) in toluene/n-heptane cosolvent using benzoyl peroxide as an initiator. Fourier transform infrared spectroscopy provides a substantial evidence of grafting of MMA and St onto EPDM. EPDM-g-MMA-St/MS resin blends (MES) were prepared by melt blending EPDM-g-MMA-St and MS resin, and the toughening effects of EPDM-g-MMA-St on MS resin were studied. The results showed that the synthesized conditions of EPDM-g-MMA-St influenced the toughening effect of EPDM-g-MMA-St on MS resin. Notched Izod impact strength of MES increased with increasing grafting ratio, grafting chain polarity of EPDM-g-MMA-St, and EPDM content in MES. Differential scanning calorimetry showed that EPDM-g-MMA-St and MS resin are compatible partially and the compatibility improves with increasing grafting chain polarity of EPDM-g-MMA-St. Transmission electron microscopy and scanning electron microscopy analysis showed that the phase structure was “sea-island” structure, and the particle diameter of EPDM-g-MMA-St increased, meanwhile, surface to surface interparticle distance decreased with an increase in EPDM content, which resulted in the toughening mechanism of MES changed into slight shear yielding of matrix from the damage mode of cavitation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and Characterization of Some Terpolymer Latices and their Application as Finishing Agents for Cotton Fabric

Abstract:

This work describes the synthesis, characterization, and evaluation of terpolymer latex prepared from glycidyl methacrylate (GMA), butyl acrylate (BuA), and Styrene (St). Five terpolymer latex samples were prepared by varying the composition ratio of BuA or St from 10% to 70% and keeping the GMA at a constant composition ratio of 20%. The other three terpolymer latex samples were also prepared by varying the composition ratio of GMA from 10% to 30% and equal composition ratios of both BuA and St. Fourier transform Infrared (FTIR) spectroscopy was used to assure the occurrence of the polymerization reaction. The morphological and rheological properties of some prepared terpolymer latices were determined. It was found that the average particle diameter, ¯D_v, of the prepared latices generally increased with an increase in the acrylic content. The rheological measurements revealed that the terpolymer latices were characterized by pseudoplastic rheological behavior. Some of the latices were used in treating cotton fabrics and the data show an increment in the air permeability resistance as well as in abrasion resistance.     

Environmental and health hazard ranking and assessment of plastic polymers based on chemical composition

Plastics constitute a large material group with a global annual production that has doubled in 15 years (245 million tonnes in 2008). Plastics are present everywhere in society and the environment, especially the marine environment, where large amounts of plastic waste accumulate. The knowledge of human and environmental hazards and risks from chemicals associated with the diversity of plastic products is very limited. Most chemicals used for producing plastic polymers are derived from non-renewable crude oil, and several are hazardous. These may be released during the production, use and disposal of the plastic product. In this study the environmental and health hazards of chemicals used in 55 thermoplastic and thermosetting polymers were identified and compiled. A hazard ranking model was developed for the hazard classes and categories in the EU classification and labelling (CLP) regulation which is based on the UN Globally Harmonized System. The polymers were ranked based on monomer hazard classifications, and initial assessments were made. The polymers that ranked as most hazardous are made of monomers classified as mutagenic and/or carcinogenic (category 1A or 1B). These belong to the polymer families of polyurethanes, polyacrylonitriles, polyvinyl chloride, epoxy resins, and styrenic copolymers. All have a large global annual production (1-37 million tonnes). A considerable number of polymers (31 out of 55) are made of monomers that belong to the two worst of the ranking model's five hazard levels, i.e. levels IV-V. The polymers that are made of level IV monomers and have a large global annual production (1-5 million tonnes) are phenol formaldehyde resins, unsaturated polyesters, polycarbonate, polymethyl methacrylate, and urea-formaldehyde resins. This study has identified hazardous substances used in polymer production for which the risks should be evaluated for decisions on the need for risk reduction measures, substitution, or even phase out.     

Effect of trimethylene carbonate segments on the structure and properties of poly(L-lactide-glycolide-trimethylene carbonate) terpolymers for biodegradable vascular stents

The total biodegradable vascular stent made of poly(L-lactide-glycolide-trimethylene carbonate) terpolymers with excellent performances has the potential to be used in a new generation of medical implant devices. In this work, the properties and structure of terpolymers were investigated, which were found to be controlled by the composition of the copolymer chain. The amorphous trimethylene carbonate segments not only disturbed the sequence regularity of the L-lactide segment, but also reduced the crystallization ability of the material. Furthermore, it is the flexible segments in the terpolymer chains that improve the plastic flow capacity, increase the flexibility of chains as well as reduce the apparent activation energy of thermal degradation of materials. Such a chain structured terpolymer exhibited good extrudability and buildability in 3D printing and formed a vascular stent with a cohesion entanglement characteristic microstructure during the process. The crush resistance with radially applied load and crush resistance with parallel plates of stent were 2561.4 mm Hg and 0.24 N/mm, respectively.     

Properties of Paper Sludge Filled Polypropylene (PP)/Ethylene Propylene Diene Terpolymer (EPDM) Composites: The Effect of Silane-Based Coupling Agent

Paper sludge was used as a filler in PP/EPDM composites and 3-aminopropyl triethoxysilane (3-APE) was used in this study as a coupling agent. The effects of filler loading and 3-APE on the mechanical properties, water absorption, morphology, and thermal properties of the composites were investigated. It was found that incorporation of a silane coupling agent (3-APE) increased the stabilization (equilibrium) torque, tensile strength, and Young's modulus but decreased the elongation at break and water absorption. Scanning electron microscopy (SEM) study of the tensile fracture surface of the composites indicated that the presence of 3-APE increased the interfacial interaction between paper sludge and PP/EPDM matrix. The addition of a silane coupling agent also increased the crystallinity of PP and thermal stability of PP/EPDM/PS composites.     

Mixing efficiency in co‐rotating batch mixer for preparation of NR/EPDM blends

An in‐house developed co‐rotating batch mixer was used to prepare the blends of natural rubber (NR) and ethylene‐propylene‐diene terpolymer (EPDM) in the present work. Phase morphology and magnitude of dispersive mixing efficiency offered by the in‐house developed co‐rotating batch mixer and a conventional counter‐rotating batch mixer were compared. It has been found that the co‐rotating batch mixer equipped with the MX2 rotor configuration could improve the dispersive mixing efficiency of NR/EPDM blends considerably. A poor state‐of‐mix in blends, particularly at high fill factor, could be overcome by the utilization of MX2 rotor configuration where the extensional flow is probably facilitated in the converging zones. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012