紫外线辐照光强对HDPE化学结构及对HDPE/PC共混体系增容效应的影响

采用FT-IR,XPS,凝胶分析以及熔融指数、接触角和力学性能测定,研究了不 同紫外辐照光强对高密度聚乙烯（HDPE）的化学结构、流动性、亲水性和辐照改性 HDPE在HDPE/聚碳酸酯（PC）共混体系中的增容效应的影响。在相同辐照时间下, 随紫外光强提高,引入HDPE分子链的含氧基团数量增加;在辐照过程中,紫外光强 对HDPE的交联有显著影响,在较低光强（32W/m~2）下辐照24h的HDPE无凝胶生成, 便在较高光强（45和78W/m~2）下辐照24h后,HDPE产生凝胶,其含量随紫外光强提 高而增多;与未辐照HDPE相比,较高光强下辐照HDPE的熔融指数有所下降,但其亲 水性得到明显改善;紫外辐照改性HDPE对HDPE/PC体系有增容作用,随紫外光强提 高其增容效应明显增强。与未增容HDPE/PC（80/20）体系相比,加入20%辐照 24hHDPE（光强78W/m~2）的HDPE/PC共混物的拉伸屈服强度从26.3MPa提高到30. 2MPa,缺口冲击强度从51J/m提高到158J/m。     

A STUDY ON MECHANICAL PROPERTIES OF γ-RAY IRRADIATED HDPE FILLED WITH SERICITE-TRIDYMITE-CRISTOBALITE*

The effect of γ-ray irradiation on the mechanical properties of high densitypolyethylene(HDPE) filled with sericite-tridymite-cristobalite(STC) was studied. The ex-perimental results show that γ-ray irradiation can improve the affinity between HDPE andSTC, and the dispersion of STC in HDPE matrix. Compared with HDPE/STC (80/20)blend, the yield stress and impact strength of irradiated HDPE (10kGy)/STC (80/20) blendare increased from 22.8 MPa and 70J/m to 28.5 MPa and 144J/m. The yield stress andimpact strength of HDPE/irradiated HDPE/STC (48/32/20) are 27.8MPa and 210J/m,respectively.     

环境温度对紫外辐照HDPE结构与性能的影响研究

采用元素、XPS、GPC分析，凝胶和力学性能测定，研究了空气中不同环境温度下紫外辐照官能化HDPE的结构、粘着性以及紫外辐照官能化HDPE对HDPE/聚乙烯醇(PVA)体系的增容作用。实验结果表明，提高环境温度可显著提高引入C-O、C(=O)O和C=O等含氧基团的速度。在相同辐照时间下，随环境温度提高，辐照HDPE的分子量下降、分子量分布变宽以及剥离强度提高的幅度增大，并在70℃时产生凝胶。较高环境温度下辐照的HDPE对HDPE/PVA共混体系有较好增容作用，在HDPE/PVA(83/17)体系中加入10%(质量分数)的70℃环境温度下辐照24h的HDPE，共混物的拉伸屈服强度和缺口冲击强度分别从30.8MPa和110J/m提高到34.9MPa和142J/m。     

MECHANICAL PROPERTIES OF OZONIZED HDPE FILLED WITH SERICITE-TRIDYMITE-CRISTOBALITE

The mechanical properties of ozonized high density polyethylene (HDPE) blended with sericite-tridymite-cristobalite (STC) were studied in this paper. The experimental results show that some oxygen containing polar groups are introduced on the molecular chain of HDPE through ozonization, the compatibility between HDPE and STC is thus improved, the mechanical properties of the blend are markedly enhanced. Compared with untreated HDPE/STC (60/40) blend, the yield strength and notched impact strength of ozonized HDPE/STC (60/40) blend are increased from 27.0MPa to 29.5MPa and from 2.8kJ/m^2 to 13.3kJ/m^2, respectively, the notched impact strength is close to that of HDPE (13.6kJ/m^2),the yield strength is in excess of 3.9MPa of that of HDPE. The yield strength and notched impact strength will be further increased to 30.7MPa and 32.4kJ/m^2 in case the ozonized HDPE is blended with STC pretreated with silane coupling agent.     

Studies of modification of HDPE and interfacial interaction of its composites with sericite

Ultraviolet irradiation, which is environment friendly and without any chemical pollution, was used to functionalize high‐density polyethylene (HDPE) and to improve the interfacial interaction of its composites with sericite in this study. The oxygen‐containing groups of C?O, C‐O, and C(?O)O were quickly introduced onto molecular chains of HDPE by ultraviolet irradiation in ozone atmosphere and the contents of the introduced oxygen‐containing groups increased with increasing the modification time. It is important to note that the irradiation time greatly decreased compared to that in air or oxygen atmosphere. After modification, the molecular weight of the irradiated HDPE decreased and its distribution became wider. The irradiated HDPE in ozone was not crosslinked, which is an advantage over the same reaction in air or oxygen atmosphere. With increasing the irradiation time, the melting temperature of the irradiated HDPE lightly decreased, while its crystallinity, hydrophilicity, and fluidity increased. The composites of HDPE/sericite were prepared. The results showed that the dispersion of sericite in the matrix and the interfacial interaction of sericite with the matrix were markedly improved for the irradiated HDPE/sericite composites. As a result, the irradiated HDPE/sericite composites showed significantly increased tensile yield strength and notched impact strength. Copyright © 2010 John Wiley & Sons, Ltd.     

紫外辐照官能化LLDPE及改性尼龙66的研究

尼龙66（PA66）是工程塑料的重要品种之一,具有高强度、耐磨、耐油、自润滑和使用温度范围广等优良特性,广泛应用于机械、汽车、电子电器等行业．但PA66在干态和低温下冲击强度偏低,吸水率大,尺寸稳定性差,使其应用范围受到一定的限制。     

氧气氛中紫外光辐照官能化HDPE的结构与性能研究

采用FT－IR，XPS，WAXD，DXC，凝胶和表面自由能力分析，研究了氧化氛中紫外辐照官能化高密度聚乙烯（HDPE）的化学结构、晶体结构和表面自由能的变化。与空气相比，在氧气氛中紫外辐照HDPE能提高C－O，C（＝O）O和C＝O等含氧基团的引入速度，同时又能降低HDPE中的凝胶含量，在空气和氧气氛中紫外辐照后，HDPE的晶型没有发生变化，仍为正交晶系；HDPE的晶胞参数a,b,c以及（110），（200），（020），（011），（111）等晶面间距基本保持不变；HDPE的熔融温度下降，但熔融热焓升高，结晶度增大，表面自由能增大，且在氧气氛中辐照HDPE的变化幅度较大。     

Structure,thermal stability,and photocrosslinking characterization of HDPE/LDH nanocomposites synthesized by melt‐intercalation

Structure, thermal properties, and influence of layered double hydroxide (LDH) fillers on photocrosslinking behavior of high‐density polyethylene (HDPE)/LDH nanocomposites have been studied in the present article. The X‐ray diffraction and transmission electron microscopy analysis demonstrate that the completely exfoliated HDPE/LDH nanocomposites can be obtained by controlling the organomodified LDH loading via melt‐intercalation. The data from the thermogravimetric analysis show that the HDPE/LDH nanocomposites have much higher thermal stability than HDPE sample. When the 50% weight loss was selected as a comparison point, the decomposition temperature of HDPE/LDH sample with 5 wt % LDH loading is ～40 °C higher than that of HDPE sample. The effects of UV‐irradiation on the HDPE/LDH nanocomposites show that the photoinitiated crosslinking can destroy the completely exfoliated structure to form the partially exfoliated structure, which decreased the thermal stability of the nanocomposites. However, the thermal stability of photocrosslinked samples can increase with increasing the UV‐irradiation time. The effect of LDH loading on the gel content of UV‐irradiated nanocomposites shows that the LDH materials can greatly absorb the UV irradiation and thus decrease the crosslinking efficiency. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3165–3172, 2006     

Compatibilization of recycled and virgin PET with radiation-oxidized HDPE

Blends of high-density polyethylene (HDPE), which cross-links on radiation, and both, recycled and pristine polyethylene terephtalate (PET), one of the most radiation-stable polymers, that contain aromatic groups, which are effective at dissipation of the energy of the ionizing radiation, were irradiated with gamma rays, in order to form a copolymer capable of improving the compatibility of the blend HDPE/PET. Due to the low content of the PET in the resulting copolymer, blends PET and radiation-oxidized HDPE, were also studied. The tensile and flexural properties were improved when the PET content was increased and when the HDPE was pre-irradiated; the largest increase in the mechanical properties was observed for PET contents between 10% and 20% (w/w). The improvement in the properties is believed to occur because of a percolation effect of the PET in the HDPE matrix and the radiation-improved compatibility by means of polar groups formed in the polyethylene. However, impact properties were observed to decrease when the PET content increased in spite of the irradiation.     

含二烯丙基双酚A醚相容剂对HDPE/PC共混体系的影响

用低密度聚乙烯接枝二烯丙基双酚Ａ醚（ＬＤＰＥ ｇ ＤＢＡＥ）作为高密度聚乙烯／聚碳酸酯（ＨＤＰＥ／ＰＣ）共混体系的增容剂,研究了其对ＨＤＰＥ／ＰＣ共混体系的影响．通过共混物形态观察、热力学性能测试和结晶性分析,发现ＬＤＰＥ ｇ ＤＢＡＥ对ＨＤＰＥ／ＰＣ共混体系有良好的增容效果．并发现了增容剂在共混物中的最佳用量为１０ｐｈｒ,提高增容剂的接枝率更有利于改善共混物的性能     

Effect of compatibilizer on morphology and properties of HDPE/Nylon 6 blends

The compatibilization effect of linear low‐density polyethylene‐grafted maleic anhydride (LLDPEgMA) and high‐density polyethylene‐grafted maleic anhydride (HDPEgMA) on high‐density polyethylene (HDPE)/polyamide 6 (Nylon 6) blend system is investigated. The morphology of 45 wt %/55 wt % polyethylene/Nylon 6 blends with three compatibilizer compositions (5 wt %, 10 wt %, and 15 wt %) are characterized by atomic force microscopic (AFM) phase imaging. The blend with 5 wt % LLDPEgMA demonstrates a Nylon 6 continuous, HDPE dispersed morphology. Increased amount of LLDPEgMA leads to sharp transition in morphology to HDPE continuous, Nylon 6 dispersed morphology. Whereas, increasing HDPEgMA concentration in the same blends results in gradual morphology transition from Nylon 6 continuous to co‐continuous morphology. The mechanical properties, oxygen permeability, and water vapor permeability are measured on the blends which confirm the morphology and indicate that HDPEgMA is a better compatibilizer than LLDPEgMA for the HDPE/Nylon 6 blend system. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 281–290     

Thermoplastic elastomer based on high‐density polyethylene/natural rubber blends: rheological,thermal, and morphological properties

Thermoplastic elastomer (TPE) comprising air‐dried sheet or natural rubber (ADS or NR) and high‐density polyethylene (HDPE) was prepared by a simple blending technique. NR and HDPE were mixed with each type of phenolic compatibilizer (HRJ‐10518 or SP‐1045) or liquid natural rubber (LNR) at 180°C in an internal mixer. The mixing torque, shear stress, and shear viscosity of the blends increased with increasing amounts of NR. Positive deviation blend (PDB) for the blends containing active hydroxyl methyl phenolic resin in HRJ‐10518 or dimethyl phenolic resin in SP‐1045 was obtained. PDB was not observed for the blends without the compatibilizers or with LNR. The blends with HRJ‐10518 or SP‐1045 were compatible or partially compatible while the LNR blends were incompatible. In the phenolic compatibilized blends, NR dispersed in the HDPE matrix was found in the NR/HDPE blends of 20/80, 40/60, and 50/50 ratios. HDPE dispersed in NR matrix was obtained in the NR/HDPE blend of 80/20 ratio, and the co‐continuous phase was accomplished in the NR/HDPE blend of 60/40 ratio. The NR/HDPE blend at 60/40 ratio compatibilized with HRJ‐10518 and fabricated by a simple plastic injection molding machine exhibited higher ultimate tensile strength and elongation at break (EB). Incorporation of parafinic oil caused a decreasing tendency in tensile strength with increases in EB. The TPNRs exhibited high elastomeric nature with low‐tension set. Copyright © 2007 John Wiley & Sons, Ltd.     

Effect of Electron Beam Irradiation and Ethylene Vinyl Acetate Copolymer on the Properties of NBR/HDPE Blends

The mechanical and physical properties of blends based essentially on nitrile butadiene rubber (NBR) and different ratios of high density polyethylene (HDPE) up to 25 parts per hundred part of rubber (phr) before and after electron beam irradiation were investigated. The values of tensile strength (TS), tensile modulus at 50% elongation (M₅₀), hardness and gel fraction % (GF%) of NBR/HDPE blends were increased with both irradiation dose and by increasing the content of HDPE in the blends. On the other hand, the values of elongation at break (E _b ) were decreased with both irradiation dose and the content of HDPE in the blends. By loading NBR/HDPE (100/25) blend with ethylene vinyl acetate (EVA) copolymer the mechanical and physico-chemical properties were improved. Moreover, the degree of improvement is proportional to the loading content of EVA.     

Gamma Radiation‐Induced Crosslinked PVA/Chitosan Blends for Wound Dressing

Crosslinked polyvinyl alcohol (PVA) and chitosan polymer blends have been prepared by using gamma irradiation. Chitosan was used in the blends to prevent microbiological growth, such as bacteria and fungi on the polymer. The physical properties of the blend, such as gelation, water absorption, and mechanical properties were examined to evaluate the possibility of its application for wound dressing. A mixture of PVA/chitosan, with different ratios, were exposed to gamma irradiation doses of 20, 30, 50 KGy, to evaluate the effect of irradiation dose on the physical properties of the blend. It was found that the gel fraction increases with increasing irradiation dose and PVA concentration in the blend. Swelling percent increased as the composition of chitosan increased in the blend. The PVA/chitosan blend has a water content in the range between 40% and 60% and water absorption between 60% and 100%. The water vapor transmission rate value (WVRT) of the PVA/chitosan blend varies between 50% and 70%. The examination of the microbe penetration shows that the prepared blend can be considered as a good barrier against microbes. Thus, the PVA/chitosan blend showed satisfactory properties for use as a wound dressing.     

辐照法制备的醋酸乙烯酯/蒙脱土纳米复合材料与HDPE和PA6共混物的研究

利用γ射线辐射引发醋酸乙烯酯(VAc)在蒙脱土(MMT)中的原位插层聚合,X射线衍射测试与透射电子显微镜观察结果表明,PVAc/MMT复合材料为纳米复合材料.其与HDPE和PA6的共混物的扫描电镜测试结果表明,PVAc-MMT纳米复合物以微胶囊的形式存在于PVAc-MMT/HDPE/PA6共混物中,均匀分散的PVAc-MMT纳米复合物改变了复合材料的相结构.热失重测试结果显示,PVAc-MMT/HDPE/PA6的起始分解温度明显高于PVAc/HDPE/PA6,热失重过程差异较大,MMT纳米粒子的存在改变了材料的结构,使材料热性能得到了改善.在PVAc-MMT/HDPE/PA6共混物中,PVAc-MMT具有增强与增韧作用.     

The mechanism of ultrasonic improvement of weld line strength of injection molded polystyrene and polystyrene/polyethylene blend parts

The effect of ultrasonic oscillations and ultrasonic oscillation‐induced modes on weld line strength of polystyrene(PS) and polystyrene/polyethylene(PS/HDPE) blend was investigated. And the mechanism of ultrasonic improvement of weld line strength of PS and PS/HDPE blend was also studied. The presence of ultrasonic oscillations can enhance the weld line strength of PS and PS/HDPE blend. Compared with mode I(ultrasonic oscillations were induced into mold at the whole process of injection molding), the induced ultrasonic oscillations as mode II(ultrasonic oscillations were induced into mold after injection mold filling) is more effective to increase weld line strength of PS and PS/HDPE blend. The mechanism for ultrasonic improvement of weld line strength of PS and PS/HDPE blend is that the ultrasonic oscillations can improve the molecular diffusion across weld line of the melt at the core, and make against the fusion of melt at the skin. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1520–1530, 2006     

Friction and wear mechanisms of polyamide 66/high density polyethylene blends

Polyamide 66 (PA66)/high density polyethylene (HDPE) blends having miscible structure were produced by compatibilization of HDPE grafted with maleic anhydride (HDPE‐g‐MAH). Mechanical and tribological properties of blends in different compositions were tested. It was found that the polymer blends greatly improved the mechanical properties of PA66 and HDPE. Blending HDPE with PA66 significantly decreased the friction coefficient of PA66; the friction coefficients of blends with different compositions were almost the same and approximately equal to that of pure HDPE; the blends with 80 vol % PA66 exhibited the best wear resistance. The transfer films, counterpart surfaces, and wear debris formed during sliding were investigated by Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC) analysis was further carried out on wear debris. These investigations indicated that the thermal control of friction model is applicable to PA66/HDPE blend, that is the friction coefficient of blend is governed by the HDPE component, which possesses a lower softening point relative to the PA66 component in this system. The wear mechanism of PA66/HDPE blend transforms from PA66 to HDPE as the HDPE content increases. PA66, as the component with higher softening point, increases the hardness of blend, enhances the ability of blend to form a transfer film on the counterface, and inhibits the formation of larger belt‐like debris of HDPE, at the same time, the presence of self‐lubricating HDPE in the system decreases the friction coefficient and the frictional heat, all of these factors are favorable for the wear resistance of PA66/HDPE blend. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2514–2523, 2005     

Additive‐like amounts of HDPE prevent creep of molten LDPE: Phase‐behavior and thermo‐mechanical properties of a melt‐miscible blend

Low‐density polyethylene (LDPE) is the preferred type of polyolefin for many medical and electrical applications because of its superior purity and cleanliness. However, the inferior thermo‐mechanical properties as compared to, for example, high‐density polyethylene (HDPE), which arise because of the lower melting temperature of LDPE, constitute a significant drawback. Here, we demonstrate that the addition of minute amounts of HDPE to a LDPE resin considerably improves the mechanical integrity above the melting temperature of LDPE. A combination of dynamic mechanical analysis and creep experiments reveals that the addition of as little as 1 to 2 wt% HDPE leads to complete form stability above the melting temperature of LDPE. The investigated LDPE/HDPE blend is found to be miscible in the melt, which facilitates the formation of a solid‐state microstructure that features a fine distribution of HDPE‐rich lamellae. The absence of creep above the melting temperature of LDPE is rationalized with the presence of tie chains and trapped entanglements that connect the few remaining crystallites. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 146–156     

Gamma radiation curing of nitrile rubber/high density polyethylene blends

Nitrile butadiene rubber (NBR) was mixed with high density polyethylene (HDPE) thermoplastics with different ratio namely (100/20), (100/40), (100/60) and (100/80). The obtained blends were subjected to gamma irradiation with varying dose from 50 to 250 kGy. The induced crosslinking and hence the improvement in the different properties were followed up as a function of irradiation dose. Mechanical properties as tensile strength, tensile modulus at 50 % elongation, elongation at break percent, permanent set and hardness were carried out as a function of irradiation dose and blend ratio. Moreover, physical properties namely, gel fraction % and swelling number were found to improve with the increase of irradiation dose up to 250 kGy and with the increase of the content of HDPE in blend. Moreover, presence of NBR enhances the shrinking properties of the obtained blend which can be used as a good heat shrinkable material.     

Influence of gamma irradiation on high density polyethylene/ethylene‐vinyl acetate/clay nanocomposites

The study of high density polyethylene (HDPE)/ethylene‐vinyl acetate (EVA)/and organically‐modified montmorillonite (OMT) nanocomposites prepared by melt intercalation followed by exposure to gamma‐rays have been carried out. The morphology and properties of the nanocomposites were studied using X‐ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and cone calorimetry. The purpose of the study focuses on the influence of gamma irradiation on the morphology, thermal stability and flammability properties of the nanocomposites. XRD studies and TEM images verified that the ordered intercalated nanomorphology of the nanocomposites was not disturbed by gamma irradiation. TGA data showed that the nano‐dispersion of clay throughout the polymer inhibited the irradiation degradation of HDPE/EVA blend, which led to the nanocomposites exhibiting superior irradiation‐resistant properties than that of the pure blend. Cone calorimetry results indicated that the improvement in heat release rate (HRR) for irradiated HDPE/EVA blend was suppressed efficiently when clay was present. Increasing clay loading from 2 to 10% was beneficial by improving the flammability properties of the nanocomposites, but promoted a rapid increase in the sub‐peak HRR at high irradiation dose level. Copyright © 2004 John Wiley & Sons, Ltd.