助剂对聚氯乙烯辐照改性的影响

本文研究了代表性的增塑剂邻苯二甲酸二丁酯(DBP)、稳定剂硬脂酸铅及多官能团单体三羟甲基丙烷三丙烯酸酯(TMPTA)和季戊四醇四丙烯酸酯(PETA)对聚氯乙烯(PVC)γ辐照改性的影响,测试了不同配方的 PVC 于不同剂量辐照时的凝胶含量、力学性能、热失重性能。结果表明,DBP 和硬脂酸铅对 PVC 的辐照交联是有益的。多官能团单体 TMPTA 和 PETA 对 PVC 的辐射交联有很大的促进作用。加入多官能团单体的 PVC 经辐照后,其拉伸强度、耐热性能和增塑剂束缚性能大大改善。     

聚乙烯/炭黑导电复合材料PTC特性的研究(Ⅱ)--辐射交联对导电复合材料PTC性能的影响

采用^60Coγ-射线对HDPE／CB导电复合材料进行辐射处理，研究了辐射剂量对于该复合材料室温电导率、PTC性能及稳定性的影响。结果发现，在50-300kGy范围内，随着辐射剂量的增加，复合材料的PTC强度增大，且复合材料的稳定性有所提高，NTC效应有所降低；同时，辐射交联对体系的室温电阻率影响不大。DSC测试表明，当辐射剂量为150kGy时，辐射处理对于HDPE的熔点、结晶度影响不大。     

辐射法制备内交联聚醚型水性聚氨酯的研究

以异佛尔酮二异氰酸酯、聚氧化丙烯二醇、二羟甲基丙酸、季戊四醇三丙烯酸酯(PETA)和甲基丙烯酸羟乙酯(HEMA)为原料,并以γ射线辐射处理,制备了内交联型水性聚氨酯(WPU)乳液。分析测试了机械稳定性、粘度、粒径及力学性能等,研究了两种封端剂含量、辐照剂量对WPU乳液性能的影响;同时研究了其胶膜的力学性能、吸水率等变化情况。结果表明,所制备的交联型WPU乳液具有较好的稳定性,平均粒径小于0.3μm,WPU经过辐照后,其粒径变化不大。与不含PETA及HEMA的样品比较,引入PETA及HEMA并辐射交联后,WPU胶膜的拉伸强度明显增加,而断裂伸长率和吸水率降低。     

功能单体改性聚氨酯丙烯酸酯的制备及粘接性能

以异佛尔酮二异氰酸酯(IPDI)、磺酸型聚酯二元醇(SDNP)为原料,以季戊四醇三丙烯酸酯(PETA)为羟基功能单体,采用无皂乳液聚合法制备了磺酸型聚氨酯丙烯酸酯乳液(SPUEA)。采用激光散射粒径仪、热重分析仪、力学性能测试和原子力显微镜(AFM)考察了PETA用量对乳液及胶膜性能的影响。结果表明:随着w(PETA)从0.5%增至2%,乳液的粒径从87 nm增至112 nm,胶膜的拉伸强度从8.2 MPa增至11.0 MPa;随着w(PETA)从1%增至2%,热失重为50%时胶膜的分解温度从314.57℃升至330.57℃,AFM分析表明两相相容性良好;在w(PETA)=2%时,胶膜的交联度为84.57%,吸水率为8%,胶膜的综合性能较佳。将SPUEA乳液作为胶粘剂应用后,随着w(PETA)从0.5%增加至2.0%,T-型剥离强度从6.98 N/mm增至11.23 N/mm,且乳液在PVC基材表面润湿性良好。     

γ射线辐射交联阻燃HDPE/EPDM 的动态燃烧特性

用锥形量热计研究了阻燃HDPE／EPDM经γ射线辐射交联前后的动态燃烧特性,实验表明,阻燃HDPE／EPDM交联后可明显降低热释放速率和最大有效燃烧热,提高了氧指数,而且提高燃烧后的成炭量,但着火时间有一定提前。     

核壳粒子POE/HDPE增韧改性聚丙烯

以聚丙烯(PP)、乙烯-1-辛烯共聚物(POE)、高密度聚乙烯(HDPE)为原料,通过熔融共混制备了具有核壳结构的PP/POE/HDPE合金。通过改变HDPE含量,研究了核壳结构对PP/POE/HDPE合金性能的影响。结果表明:当w(HDPE)大于15%时,PP/POE/HDPE合金中有明显的核壳结构,以HDPE为核,弹性体POE为壳,不仅能形成单核结构,还能形成多核结构;随着HDPE含量增加,PP的结晶度下降;当w(HDPE)为20%时,与纯PP相比,PP/POE/HDPE合金的冲击强度提高了139.5%,而拉伸强度和弹性模量基本不变。     

HDPE/EVA二元共混物敏化辐射交联与性能

以三烯丙基异氰脲酸酯(TAIC)为交联敏化剂,采用电子束对高密度聚乙烯(HDPE)与乙烯-乙酸乙烯酯共聚物(EVA)的共混物进行辐射交联。研究了TAIC的敏化作用机理以及辐照剂量对共混物的力学性能、电学性能以及结晶度与交联度之间的相互关系。结果表明:TAIC对共混体系的交联反应具有敏化作用,可显著减小辐射剂量,共混物产生交联反应后可获得较高的凝胶含量;在辐射剂量120 kGy时,1%的TAIC即可使复合材料的拉伸强度提高了20%,断裂伸长率达到475.4%。此外,电子束辐射并未改变复合材料的晶型,随着辐射剂量的增加,复合材料的结晶温度、熔点、介电常数下降,共混物的介电损耗在120 kGy剂量下达到最佳。     

甜高粱杆含量对甜高粱杆/高密度聚乙烯复合材料力学性能与热稳定性的影响

采用注塑成型法制备了甜高粱杆/高密度聚乙烯(HDPE)复合材料,借助电子万能力学试验机、动态热机械分析仪、同步热分析仪以及扫描电镜等仪器,研究了甜高粱杆含量对甜高粱杆/HDPE复合材料力学性能及热稳定性的影响。结果表明:随着甜高粱杆含量的增加,甜高粱杆/HDPE复合材料的拉伸强度和弯曲强度均呈先增大后减小的趋势,但冲击强度逐渐降低;甜高粱杆的加入对甜高粱杆/HDPE复合材料的热稳定性影响较小。     

PETA对层压复合用水性聚氨酯丙烯酸酯乳液的改性研究

以聚酯多元醇、二羟甲基丙酸、二苯基甲烷二异氰酸酯和季戊四醇三丙烯酸酯(PETA)等为原材料,加入引发剂进行自由基聚合制备了水性聚氨酯丙烯酸酯乳液(PUA)。对该乳液进行了性能表征,并着重研究了PETA对乳液性能以及在层压复合包材上应用性能的影响。研究结果表明:当w(PETA)=2%(相对于PUA乳液总质量而言)时,PUA乳液的稳定性较好,PUA胶膜的拉伸强度达到13 MPa,胶膜吸水率为7.4%,铝箔基的剥离强度为14.3 N/(25 mm)。各项数据表明该PUA乳液满足在层压复合中的应用要求。     

POM共混增韧改性研究

研究了POM COPA、POM LDPE和POM HDPE三种共混体系,测试了不同配比共混物的冲击强度,对POM COPA及紫外线辐射的HDPE进行了红外光谱(FT IR)分析。结果表明:(1)在三种共混体系中,COPA对POM的增韧效果最佳,且COPA与POM分子间有氢键作用;(2)EVA在POM LDPE及POM HDPE共混体系中起相容剂的作用;(3)HDPE经紫外线辐射后,由于在其分子链上引入了极性羰基,从而大大提高了对POM的增韧效果。     

多乙烯基单体对溴化丁基胶电子束交联的敏化效应

观察到溴化丁基胶(BIIR)在加速器产生的电子束辐照下可发生交联反应,测得其凝胶化剂量为12 kGy。在剂量较低时辐照产物的凝胶含量与交联密度均随剂量增加而提高,但在80 kGy后则随剂量增加而呈下降趋势。试验了5种多乙烯基单体以敏化BIIR的交联反应,从而避免高剂量下的降解现象。结果表明TMPT(三甲基丙烯酸三羟甲基丙烷酯)是有效的敏化剂,配有TMPT的BIIR交联产物其拉伸强度随TMPT用量增大而明显提高。     

钢塑复合管专用交联HDPE的研制

研制了钢塑复合管专用交联高密度聚乙烯(HDPE),并研究了其性能。结果表明．交联后的HDPE具有更加优异的力学性能;随着交联剂(VS—1)用量的增加,交联HDPE的拉伸强度、冲击强度、凝胶率增加,但其断裂伸长率和流动性下降,当VS—l质量分数为1．8％时,交联HDPE的性能最佳：拉伸强度为40．8MPa,冲击强度为117J／m^2,凝胶率为73．8％,断裂伸长率为280％,熔体流动指数为0．3g／10min;将5000S与2480共混,并添加质量分数不低于1．0％的流变剂YL—1,其加工流动性最佳;用二月桂酸二丁基锡作催化剂使HDPE的交联反应在5h后就完成了90％以上．比不加催化剂提前15h。     

辐射交联聚乙烯敏化剂的应用研究

考察了敏化剂和聚合物改性添加剂对聚乙烯的辐射交联效应。测定了敏化剂及添加剂用量，吸收剂量对交联聚乙烯各项性能的影响。结果表明，敏化剂及添加剂的加入能在较低吸收剂量下有效地提高ＰＥ的凝胶分数，改善其机械性能，提高了热性能。     

Thermal and wide angle X‐ray analysis of chemically and radiation‐crosslinked low and high density polyethylenes

Low and high density polyethylenes (PE) were crosslinked by two methods, namely, chemically by use of different amounts of tert‐butyl cumyl peroxide (BCUP) and by irradiation with different doses of electron beam. A comparison between the effects of these two types of crosslinking on crystalline structure, crystallinity, crystallization, and melting behaviors of PE was made by wide angle X‐ray diffraction and DSC techniques. Analysis of the DSC first heating cycle revealed that the chemically induced crosslinking, which took place at melt state, hindered the crystallization process and decreased the degree of crystallinity, as well as the size of crystals. Although the radiation‐induced crosslinking, which took place at solid state, had no significant influence on crystalline region, rather, it only increased the melting temperature to some extent. However, during DSC cooling cycle, the crystallization temperature showed a prominent decrease with increasing irradiation dose. The wide angle X‐ray scattering analysis supported these findings. The crystallinity and crystallite size of chemically crosslinked PE decreased with increasing peroxide content, whereas the irradiation‐crosslinked PE did not show any change in these parameters. As compared with HDPE, LDPE was more prone to crosslinking (more gel content) owing to the presence of tertiary carbon atoms and branching as well as owing to its being more amorphous in nature. HDPE, with its higher crystalline content, showed relatively less tendency toward crosslinking especially by way of irradiation at solid state. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3264–3271, 2006     

过氧化物交联HDPE材料的研究

研究了交联用高密度聚乙烯(HDPE)的种类、交联剂二叔丁基过氧化物(DTBP)、助交联剂T的用量对交联HDPE复合材料结构和性能的影响。选用辛烯为共聚单体和支化度(每1000C中的甲基数)为3.2的HDPE为原料树脂,主交联剂DTBP和助交联剂T的质量分数分别为0.15%,0.20%时,材料的各项性能符合交联HDPE管材的要求。     

PTFE的辐射交联及其应用

利用电子束高温辐照PTFE,制备出交联PTFE样。通过红外光谱法（IR）、差示扫描量热分析法（DSC）等各种方法研究辐射交联PTFE的性能。结果表明：与未辐照PTFE相比,交联PTFE的透明度明显增加,熔点下降,耐磨性能明显提高。     

Radiation effects on HDPE/EVA blends

In this article, we discuss the radiation effects of high‐density polyethylene (HDPE)/ethylene–vinyl acetate (EVA) copolymer blends. In comparison with the low‐density polyethylene/EVA blends, the EVA content in the HDPE/EVA blends had a lower enhancement effect on radiation crosslinking by γ‐ray irradiation in air. The phenomenon is discussed with the compatibility, morphology, and thermal properties of HDPE/EVA blends. The HDPE/EVA blends were partly compatible in the amorphous region, and radiation crosslinking of the HDPE/EVA blend was less significant, although increasing the amorphous region's content of the HDPE/EVA blends and the vinyl acetate content of EVA were beneficial to radiation crosslinking. The good compatibility was a prerequisite for the enhancement effect of EVA on the radiation crosslinking of the polyethylene/EVA copolymer. The radiation crosslinking and the degradation mechanism of HDPE/EVA blends were examined quantitatively by a novel method, the step analysis process of irradiated HDPE/EVA blends with a thermal gravimetric analysis technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 553–558, 2002     

Effect of crosslinking on the positive temperature coefficient stability of carbon black‐filled HDPE/ethylene‐ethylacrylate copolymer blend system

Carbon black‐filled high‐density polyethylene (HDPE)/ethylene ethylacrylate copolymer (EEA) blends were prepared and the effect of crosslinking of the blends on the positive temperature coefficient (PTC) stability was investigated. By irradiation and silane‐crosslinking methods, crosslinked composites with various degrees of crosslinking were obtained. Crosslinking of the matrix polymer led to the disappearance of the negative temperature coefficient (NTC) phenomenon. Also, the PTC intensity increased with an increasing degree of crosslinking. The PTC stability of silane‐crosslinked samples was notably improved at heat cycles of 140°C. This was sufficiently improved by both the silane‐ and radiation‐crosslinking methods when they were treated at 85°C. Therefore, the limiting temperature of self‐regulating heat is about 85°C. Both radiation‐ and silane‐crosslinked samples are thought to be of use to the industry.     

SBS/PE-LD共混物的强化辐射交联研究

研究了多官能团单体的用量、官能团数目以及辐射剂量对苯乙烯丁二烯共聚物（SBS）与低密度聚乙烯（PE-LD）共混物的强化辐射交联效应,测试了共混物的辐射交联程度、力学性能与形状记忆性能。结果表明,随辐射剂量的增加,SBS/PE-LD共混物的交联程度增加;多官能团单体的加入能够提高共混物的交联程度;相同辐射剂量时,官能团数目越多,交联程度越高;辐射剂量高于150 kGy时,多官能团单体的加入可以提高SBS/PE-LD共混物的拉伸强度;强化辐射交联SBS/PE LD共混物具有优异的形状记忆性能。     

Studies on the properties and structure of electron‐beam crosslinked low‐density polyethylene/poly[ethylene‐co‐(vinyl acetate)] blends

Blends of low‐density polyethylene (LDPE) and poly[ethylene‐co‐(vinyl acetate)] (PEVA), crosslinked by electron‐beam (EB) radiation, formed separate crystalline lattices with a homogeneous amorphous phase. The crystallinity of the EB‐exposed samples slightly decreased, as verified by a slight reduction in the densities and melting heats and temperatures of the samples. The results obtained from both gel content and hot set tests showed that the degree of crosslinking in the amorphous regions was dependent on the dose and blend composition. The molecular weights between the crosslinks, measured from creep data, showed that an increasing PEVA content resulted in tighter network structures, thus supporting the idea that the crosslinking density at a given irradiation dose depends on the amorphous portions of the polymers. Addition of trimethylolpropane trimethacrylate as a radiation sensitizer enhanced the gel content of the neat polyethylene significantly, while the addition of an antioxidant showed the reverse effect. A significant improvement in the tensile strength of the neat PEVA samples was obtained upon EB radiation up to 210 kGy. The irradiated LDPE/PEVA blends showed improved tensile strength and elongation at break when compared to LDPE. Copyright © 2004 Society of Chemical Industry