Studies on high density polyethylene (HDPE) functionalized by ultraviolet irradiation and its application

The structure and properties of high density polyethylene (HDPE) functionalized by ultraviolet irradiation at different light intensities in air were studied by electron analysis, FTIR spectroscopy, contact angle with water, differential scanning calorimetry and mechanical properties measurement. The results show that oxygen‐containing groups such as C?O, C—O and C(?O)O were introduced onto the molecular chain of HDPE following irradiation, and the rate and efficiency of HDPE functionalization increased with enhancement of irradiation intensity. After irradiation, the melting temperature, contact angle with water and notched impact strength of HDPE decreased, the degree of crystallinity increased, and their variation amplitude increased with irradiation intensity. Compared with HDPE, the yield strength of HDPE irradiated at lower light intensity (32 W m^?2 and 45 W m^?2) increases monotonically with irradiation time, and the yield strength of HDPE irradiated at higher light intensity (78 W m^?2) increases up to 48 h and then decreased with further increase in irradiation time. The irradiated HDPE behaved as a compatibilizer in HDPE/polycarbonate (PC) blends, and the interface bonding between HDPE and PC was ameliorated. After adding 20 wt% HDPE irradiated at 78 W m^?2 irradiation intensity for 24 h to HDPE/PC blends, the tensile yield strength and notched Izod impact strength of the blend were increased from 26.3 MPa and 51 J m^?1 to 30.2 MPa and 158 J m^?1, respectively. Copyright © 2003 Society of Chemical Industry     

HDPE／CaCO3复合材料片材制品的力学性能

通过制备不同含量的微米级和纳米级碳酸钙(CaCO3)填充的高密度聚乙烯(HDPE)片材制品,对其力学性能进行分析。研究了微米级和纳米级CaCO3对HDPECaCO3复合材料片材制品的力学性能的影响规律,并对此影响规律进行了合理的解释。     

高密度聚乙烯／聚碳酸酯共混体系性能的初步研究

本文介绍发不同牌号高密度聚乙烯和聚碳酸酯对ＨＤＰＥ／ＰＣ共混物性能的影响结果。同时以ＰＥ接枝马来酸酐和自ＰＥ接枝烯丙基双酚Ａ醚及ＰＥ接枝烯丙基双酚Ａ作为增容剂，研究了不同增容剂、ＰＣ含量和增容剂含量对ＨＤＰＥ／ＰＣ共混物力学和热性能的影响。     

Properties of biomineralized (CaCO3) PVP-CMC hydrogel with reference to its cytotoxicity

The authors focus on properties of biomineralized (CaCO₃) PVP-CMC hydrogel (designated as I–X) including cytotoxicity assay using primary mouse embryonic fibroblasts. The biomineralized samples (VII–X) showed >80% cell viability, was selected for further characterizations. FTIR and XRD indicate deposition of CaCO₃ within the PVP-CMC hydrogel matrix, SEM shows changes in morphology and pore diameter (VII and VIII: 1–12 µm; IX: 10–70 µm; X: 70–170 µm), TGA determines the decomposition scenario of CaCO₃, and tensile strength of samples (VII–X) ranged between 0.04 and 1.0 GPa, which practically corresponds to the modulus of cancellous bone.     

Effects of High-Energy Electron Beam Irradiation on the Properties of Flame-Retardant HDPE/EVA/Mg(OH)2 Composites

The mechanical properties of flame-retardant high-density polyethylene/ethylene vinyl-acetate copolymer/magnesium hydroxide (HDPE/EVA/Mg(OH)₂) composites for cable materials are usually poor due to the high loading of the filler. In this study, high-energy electron beam irradiation was applied to HDPE/EVA/Mg(OH)₂ composites in the presence of triallylisocyanurate, an irradiation sensitizer. The effects of high-energy electron beam irradiation on the properties of irradiated HDPE/EVA/Mg(OH)₂ composites were investigated through the measurements of gel content, limiting oxygen index, tensile testing, thermogravimetric analysis, and scanning electron microscope. The results showed that the thermal, mechanical and flame-retardant properties of the HDPE/EVA/Mg(OH)₂ composites were improved by using high-energy electron beam irradiation.     

Studies of Thermal Conductivity of Nano CaCO3/HIPS Composites by Unsteady State Technique and Simulation with Nielsen's Model

Differential scanning calorimeter (DSC) and thermal conductivity meter were used for measurement of thermal conductivity by unsteady state technique of the high impact polystyrene (HIPS) composites filled with 0.5, 1.5, and 2.5 wt.% of CaCO₃ nano particles. A comparison of experimental and theoretical values of (K _c /K _m) was done using MATLAB software fitting in Nielsen's model of thermal conductivity for polymers containing low limit of volume fraction. The packing fraction (Φ _max) and geometry and orientation dependent parameter (A) of the nanofiller were assumed as 0.10 and 100, respectively, which are most fitted for this model. The effect of nanosize on thermal conductivity was well predicted by plotting different values of thermal conductivity at various source temperatures. The violation of the theoretical values because of local molecular vibration at higher temperature is highlighted promisingly in the plots.     

Novel Comb-Like Copolymer Dispersant for Polypropylene/CaCO3 Composites and Its Influence on Dispersion,Crystallization, Mechanical,and Thermal Properties

A novel comb-like copolymer with carboxyl group as an anchoring group and polycaprolactone as a solvent chain was first used as the dispersant of CaCO₃ particles in polypropylene (PP). The dispersion of CaCO₃ particles in PP matrix was significantly improved in the presence of comb-like copolymer dispersant because of the strong repulsive force caused by steric hindrance effect. The influences of the coating amount of comb-like copolymer dispersant on crystallization behaviors, mechanical properties, and thermal stabilities were systematically investigated. The crystallization temperature, crystallinity, and crystallization rate of PP/CaCO₃ composites prepared with monolayer-coated CaCO₃ were all improved, where the monolayer comb-like copolymer coating remained as a rigid layer and provided a noticeable nucleating effect. The PP/CaCO₃ composites coated with monolayer SP comb-like copolymer also had the best mechanical properties, including tensile strength, Young’s modulus, flexural modulus, and impact strength because of the good dispersion of CaCO₃ particles in PP matrix. The thermal stability of PP/CaCO₃ composites were measured by thermogravimetric analysis. The results showed that SP comb-like copolymer dispersant treated CaCO₃ filled composites had excellent thermal stability than untreated and neat PP, especially for the composite prepared with monolayer-coated CaCO₃.     

DPE/PC共混体系的增容剂分子设计与合成

介绍了高密度聚乙烯 (HDPE) /聚碳酸酯 (PC)共混体系的增容剂的分子设计与合成技术。采用了低密度聚乙烯 (LDPE)在引发剂过氧化苯甲酰 (BPO)存在下与二烯丙基双酚A(DABPA)在二甲苯中进行溶液接枝共聚反应的工艺。通过重量法和X 射线光电子能谱 (XPS)证实了接枝共聚物 (LDPE g DABPA)的存在。研究了引发剂BPO用量、单体DABPA用量、反应时间及反应温度对接枝率的影响 ,确定了合成LDPE g DABPA最佳接枝率的工艺条件。采用红外光谱研究增容的共混体系证明 ,LDPE g DABPA与PC之间的确存在强的相互作用 ,能够改善体系的相容性     

The Effect of Phase Structure on the Tribological Properties of PA66/HDPE Blends

Summary: In this paper, immiscible, partially miscible and miscible blends of polyamide 66 (PA66) and high density polyethylene (HDPE) were obtained by changing compatibilizer concentrations. Mechanical and tribological properties of materials were tested. It was found that the addition of compatibilizer greatly improved the mechanical properties of PA66/HDPE blends. The wear of PA66/HDPE blends was strongly affected by the phase structure. The best blend for lower friction coefficient and higher wear resistance was the blend with a miscible structure, which significantly improved the tribological properties of PA66 and HDPE. SEM investigations on the worn surface and the steel counterface indicated that, for the immiscible and partially miscible blend systems, the dispersed HDPE particles were pulled out from the worn surfaces during sliding because of the poor adhesion between HDPE and PA66, while this was not observed in the miscible blend system.

SEM micrograph of the worn surface formed by PA66/HDPE blend without HDPE‐g‐MAH.     

Separation of copper from cobalt in sulphate solutions by using CaCO3

Lime neutralization is widely used to precipitate heavy metals including copper and cobalt from wastewater. Limestone (calcium carbonate: CaCO₃) is too stable to be used directly for this purpose. Grinding of CaCO₃ in the solutions of copper and cobalt sulphate was conducted to raise its reactivity. During the mechanochemical activation, CaCO₃ reacted with copper sulphate but not significantly with cobalt sulphate and this phenomenon allowed an easy separation of copper from cobalt. The residual of Cu(II) ions in solution could be controlled at less than 0.1%, meanwhile more than 90% of the Co(II) ions remained in aqueous solution.     

Studies on Mechanical,Thermal, and Flame Retarding Properties of Polybutadiene Rubber (PBR) Nanocomposites

An effect of nanosize CaCO₃ on physical, mechanical, thermal and flame retarding properties of PBR was compared with commercial CaCO₃ and fly ash filled PBR. CaCO₃ at the rate of 9, 15, and 21 nm were added in polybutadiene rubber (PBR) at 4, 8 and 12 wt.% separately. Properties such as swelling index, specific gravity, tensile strength, Young's modulus, elongation at break, modulus at 300% elongation, glass transition temperature, decomposition temperature, flame retardency, hardness, and abrasion resistances were determined. The swelling index decreased and specific gravity increased with reduction in particle size of fillers in PBR composites. There was significant improvement in physical, mechanical, thermal and flame-retarding properties of PBR composites due to a reduction in the particle size of fillers. Maximum improvement in mechanical and flame retarding properties was observed at 8 wt.% of filler loading. This increment in properties was more pronounced in 9 nm size CaCO₃. The results were not appreciable above 8 wt.% loading of nano fillers because of agglomeration of nanoparticles. In addition, an attempt was made to consider some thermodynamically aspects of resulting system. The cross-linkage density has been assessed by Flory-Rehner equation in which free energy was increased with increase in filler content.     

HDPE/mLLDPE混炼后的性能与结构

高密度聚乙烯/茂金属线性低密度聚乙烯(HDPE/mLLDPE)40/60共混物经混炼器混炼后的冲击强度比未经混炼器混炼的HDPE增加了96．2%,比未经混炼器混炼的mLLDPE增加了27．0%,其拉伸强度比未经混炼器的mLLDPE增加了49．1%。这表明在混炼器的强剪切分散作用下,HDPE,mLLDPE共混对HDPE和mLLDPE有显著的增韧作用。其微观结构测试表明,mLLDPE与HDPE形成了共晶结构,HDPE含量高的HDPE/mLLDPE共混体系试样内部的晶粒尺寸更为均一。     

HDPE/LLDPE/CaCO3共混物注射成型收缩率的研究

研究了高密度聚乙烯（HDPE）／线性低密度聚乙烯（LLDPE）共混物及其碳酸钙（CaCO3）填充体系的注射成型收缩率,分别用示差扫描量热仪（DSC）和AR2000高级流变仪分析测定了共混物的结晶度和熔体黏度,并探讨了不同配比下共混物结晶度和熔体黏度与成型收缩率的关系。结果表明,在加工条件不变的情况下,HDPE／LLDPE共混物成型收缩率受结晶度和熔体黏度的显著影响。随LLDPE用量的增加,收缩率的变化明显分为三个阶段,先迅速增大,然后变化减缓,最后又逐渐减小。加入少量铝酸酯活化的CaCO3可以显著降低共混物的成型收缩率。     

HDPE／UHMWPA层状分散合金的亚微形态,流变性能及体系相容性研究

本文研究了HDPE/UHMWPA共混体系的相容性及各组分的流变性能,据此选取了制备层状分散合金的工艺参数,获得了具有各种层状分散相态的共混物。研究结果表明:在低剪切及分散相粘度大于连续相粘度时,分散相易被层化;体系相容性和外剪切场对层状平板的尺寸及形状有明显的影响。     

Toughening and reinforcement of HDPE/CaCO3 blends by interfacial modification—interfacial interaction

To improve the mechanical properties and structure of HDPE/CaCO₃ composites, a type of modifier, consisting mainly of carboxylated polyethylene (CPE), and a type of CaCO₃ grafted with acrylamide (CaCO₃(SINGLE BOND)A) were used. The carboxyl group content of CPE was from 1 to 10%. The amide group content on the surface of the modified CaCO₃ was from 0.2 to 1.8%. The interfacial structure and interaction of ternary blends of HDPE, CPE, and CaCO₃(SINGLE BOND)A were studied. The results indicate that the higher the amide group content and the carboxyl group content, the higher the tensile and impact strength. This behavior has been attributed to a series of chemical and physico-chemical interactions taking place between the two components during the blending process which were confirmed by FTIR and extraction experiments. The improvement of interfacial adhesion by the CPE and CaCO₃(SINGLE BOND)A was also clearly revealed in the SEM of the fracture surface. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1275–1281, 1997     

HDPE/nano-CaCO3复合材料性能研究

采用熔融共混法制备出了高密度聚乙烯(HDPE)/纳米碳酸钙(nano-CaCO3)复合材料。研究了nano-CaCO3的加入量对复合材料力学性能的影响,利用扫描电镜(SEM)分析了nano-CaCO3在HDPE基体中的分散性。结果表明,随着nano-CaCO3用量的增加,HDPE/nano-CaCO3复合材料的冲击强度和拉伸强度均呈现出先增加后降低的趋势,而弯曲模量呈增加趋势;随着用量的增加,nano-CaCO3在HDPE基体中的分散性逐渐变差。     

母料法制备HDPE/POE/CaCO3薄膜的性能研究

采用母料法(二次挤出法)制备HDPF/POE/CaCO3共混物薄膜.比较了母料法与一次挤出法制得薄膜的力学性能与透光率.结果表明,在工艺参数相同时,母料法制备的薄膜力学性能比一次挤出法要好,而薄膜透光率基本相同.当POE、重质碳酸钙质量分数均为10%时,母料法制备的薄膜拉伸强度、断裂伸长率、单位冲击破损质量比纯HDPE薄膜分别提高了24.8%、27.5%、121%,比二次挤出法制备的薄膜力学性能分别提高了36.8%、14.1%、52.5%.     

Preparation of hierarchical mesoporous CaCO3 by a facile binary solvent approach as anticancer drug carrier for etoposide

To develop a nontoxic system for targeting therapy, a new highly ordered hierarchical mesoporous calcium carbonate nanospheres (CCNSs) as small drug carriers has been synthesized by a mild and facile binary solvent approach under the normal temperature and pressure. The hierarchical structure by multistage self-assembled strategy was confirmed by TEM and SEM, and a possible formation process was proposed. Due to the large fraction of voids inside the nanospheres which provides space for physical absorption, the CCNSs can stably encapsulate the anticancer drug etoposide with the drug loading efficiency as high as 39.7 wt.%, and etoposide-loaded CCNS (ECCNS) nanoparticles can dispersed well in the cell culture. Besides, the drug release behavior investigated at three different pH values showed that the release of etoposide from CCNSs was pH-sensitive. MTT assay showed that compared with free etoposide, ECCNSs exhibited a higher cell inhibition ratio against SGC-7901 cells and also decreased the toxicity of etoposide to HEK 293 T cells. The CLSM image showed that ECCNSs exhibited a high efficiency of intracellular delivery, especially in nuclear invasion. The apoptosis test revealed that etoposide entrapped in CCNSs could enhance the delivery efficiencies of drug to achieve an improved inhibition effect on cell growth. These results clearly implied that the CCNSs are a promising drug delivery system for etoposide in cancer therapy.     

紫外光照射对新型双马来酰亚胺基复合材料性能的影响

利用紫外灯对T700碳纤维增强双马来酰亚胺基复合材料(T700/5429)进行了90d的紫外光照射,采用扫描电子显微镜、万能试验机、傅里叶变换红外光谱仪及动态热机械分析仪分析了紫外光照射前后复合材料的表面形貌、弯曲断面形貌、特征基团透射峰面积及力学性能的变化情况.结果表明,经90d的紫外光照射后,T700/5429表面纤维出现裸露,树脂基体有脱落的现象;而复合材料的面内压缩强度和弯曲强度保持较好.透射峰面积的变化、纤维裸露及玻璃化转变温度的降低表明了90d紫外光照射会使双马来酰亚胺树脂基体的酰亚胺环裂解.