基于辐照交联聚丙烯发泡材料制备分析

文中以石化股份有限公司PP的T36F,以及辐照敏化剂（季戊四醇三丙烯酸酯）d的PETA,进行了辐照交联聚丙烯发泡材料制备分析,实验结果可知电子束辐照交联改性的方法是有效的,这一研究对于相关技术的推广具有一定的意义。     

辐照交联在电缆工业中的应用

一、概述高聚物的交联可以用化学法或辐照来实现。其中化学交联是一种传统技术,它是利用传导热使高聚物和交联剂起反应,形成交联。而辐照交联研究始源于本世纪四十年代。随着大功率辐照源的出现,A.Charlcsby 于1952年介绍了对低密度聚乙烯用辐照法生产“新型塑料”的方法,之后又研究出了用同样方法来交联天然橡     

成核剂对聚丙烯辐照交联行为的影响

系统研究了聚丙烯的辐照交联行为,证明加有成核剂的聚丙烯辐照稳定性好,容易制成性能优异的辐照交联聚丙烯。根据此研究结果,发明了“高性能辐照交联聚丙烯的制备”这一专利技术。此技术在化工、建筑等方面均有广泛的应用前景。     

辐照交联聚乙烯(PE-X_c)管材

辐照交联聚乙烯(PE-X)c管材是先挤出未交联的聚乙烯管材后,再经过电子加速器或钴-60放射源照射而形成的交联管材。采用电子加速器的物理交联法生产的交联管材,具有交联度均匀、纯净度高、卫生性能好、质量可靠的显著特点。本文对辐照交联聚乙烯(PE-X)c管材的原料、生产设备及工艺、性能及应用范围作了简要论述。     

辐照交联聚乙烯绝缘电缆的综述

综述了辐照交联聚乙烯电缆的发展过程、技术特点以及辐照交联聚乙烯电缆的制造技术。同时提出了聚乙烯电缆辐照交联中的技术难题。     

辐照交联超高分子量聚乙烯的生物摩擦学性能研究

采用γ-射线对医用超高分子量聚乙烯(UHMWPE)进行辐照交联处理,研究了辐照交联对医用UHMWPE力学性能和生物摩擦学性能的影响。结果表明:辐照交联使UHMWPE的结晶度、硬度、弹性性能、抗划痕能力和摩擦磨损性能提高,但降低了UHMWPE的塑性性能。     

可辐照交联聚乙烯热收缩管专用料的研制

通过对辐照剂量及热塑性弹性体、交联敏化剂等用量的选择,研制出性能符合辐照交联热收缩管专用料技术指标的聚乙烯料。     

纤维素辐照改性及其应用

辐照技术利用电离辐射诱发物理化学反应(例如交联、聚合、接枝、降解等)对材料进行加工或改性,与常规加工方法相比,具有节能、无环境污染等特点。将辐照技术应用于纤维素改性过程近年已成为非动力核技术应用领域研究的热点之一。本工作对目前纤维素的辐照技术及其基本反应机理进行了概述,其中包括纤维素膜材料、纤维素水凝胶、纤维素微晶/纳米材料,并对纤维素辐照改性过程的辐照环境,包括溶剂、敏化剂、温度、辐照剂量、环境氛围、结晶度等进行了总结。     

电子束辐照对聚对苯二甲酸丁二醇酯的影响

采用电子加速器对聚对苯二甲酸丁二醇酯(PBT)进行辐照,研究了吸收剂量、交联助剂及辐照气氛对PBT凝胶含量的影响,以及辐照交联对PBT力学性能及结晶行为的影响。结果表明,PBT树脂对电子束辐照相对稳定,交联助剂TMPTA能有效促进PBT的辐照交联;辐照后的PBT拉伸强度较未辐照时明显提高,断裂伸长率相应地略有降低;而同一吸收剂量下,交联助剂的添加量对PBT的拉伸强度及断裂伸长率无明显影响;PBT辐照交联后熔点降低,熔融焓减小,形成尺寸较小、结构不完善的晶体。     

辐照交联聚乙烯管材专用树脂的研制

通过对辐照交联管材基体树脂及助剂体系的配方研究,讨论了敏化剂品种、用量及抗氧剂用量对体系交联度的影响,确定了辐照交联管材专用树脂的最佳配方,即高密度聚乙烯(6366M)和线形低密度聚乙烯(7042)的配比为80/20,敏化剂M-1和抗氧剂的加人量分别为2.5%和2.5%。还考察了辐照剂量对体系力学性能及结晶度的影响。结果表明:随着辐照剂量的增加,拉伸强度、断裂伸长率下降,材料发生交联的同时也发生了降解。随着辐照剂量的增加,结晶度基本没有发生变化,这说明交联只是发生在非晶区或晶区与非晶区的边缘。加工应用实验表明,专用树脂的各项性能达到进口树脂ME2592的水平。     

交联聚乙烯的应用及技术进展

对交联聚乙烯(CLPE)的应用情况及生产技术的发展概况进行了综述，并从交联原理和生产工艺等方面对辐射交联、紫外光交联、过氧化物交联和硅烷交联等CLPE生产方法进行了对比介绍。由于硅烷交联和过氧化物交联比较容易实现且投资相对较少而被广泛应用，而辐射交联和紫外光交联对厚制品很难实现均匀交联，仅限于薄制品领域。建议国内相关单位加大专用料的研制开发力度，在提高塑料加工设备的精度和水平上多做工作。     

Irradiation effects on polycaprolactone

The structure and some physical properties of γ-irradiated polycaprolactone (PCL), a semi-crystalline linear saturated polyester, were studied as function of the irradiation dose level. The critical dose level for gel formation is 26 Mrad and above this irradiation dose the number of scission events is similar to the number of crosslinking events. G.p.c. results show that the initial rather narrow molecular weight distribution gradually widens with increasing dose in the pre-gelation region. A significant difference between first and second d.s.c. scans of irradiated PCL is shown and explained. Scission and crosslinking reactions associated with the irradiation process occur preferentially in the non-ordered regions. Small irradiation doses, 2–5 Mrad, are shown to have a dramatic effect on the tensile elongation at break by converting ductile PCL samples into brittle materials.     

辐照在高分子材料制备与改性研究中的新动向

扼要介绍了含氟聚合物辐射交联、聚烯烃辐照改性、辐照过程中自由基形成机理、通过辐照制备具有某些特殊结构和性能聚合物的方法、辐照效应与聚合结构和辐照条件关系等领域研究的最近进展。     

Electron‐beam irradiation of poly(vinyl chloride)/epoxidized natural rubber blends in presence of trimethylolpropane triacrylate

Electron‐beam initiated crosslinking of poly(vinyl chloride)/epoxidized natural rubber blends, which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20–200 kGy) and concentrations of TMPTA (1–5 phr). The gel content increased with the irradiation dose and the TMPTA level, although the increase was marginal at higher doses and higher TMPTA levels. Blends containing 3–4 phr TMPTA achieved optimum crosslinking, which in effect caused the maximum tensile strength (TS) at a dose of 70 kGy. A further addition of TMPTA caused a decline in the TS above 40 kGy that was due to embrittlement, which is a consequence of excessive crosslinking and the breakdown of the network structure. The possible formation of a more open network as a result of the breakdown of the network structure was further confirmed by the modulus results. Dynamic mechanical analysis (tan δ curve) and scanning electron microscopy studies on samples irradiated at 0 and 200 kGy were undertaken in order to gain further evidence on the irradiation‐induced crosslinking. The plasticizing effect of TMPTA prior to irradiation and the formation of microgels upon irradiation were also discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1926–1935, 2001     

超高相对分子质量聚乙烯交联研究进展

超高相对分子质量聚乙烯(UHMWPE)因其优异的综合性能被广泛用于人工关节替代等材料中,但磨损现象一直是造成替代关节破坏而失效的最重要因素。近年来通过交联提高UHMWPE的耐磨性已成为学术界研究的一大热点。综述了UHMWPE在交联方面的最新研究成果。研究重点集中在通过各种射线辐照、化学方法、硅烷接枝获得UHMWPE的交联。     

Structure and properties of closed‐cell foam prepared from irradiation crosslinked silicone rubber

Silicone rubber foam was prepared through crosslinking with electron beam irradiation and foaming by the decomposing of blowing agent azobisformamide (AC) in hot air. The crosslinking and foaming of silicone rubber was carried out separately, which was different from the conventional method of chemical crosslinking and foaming. After foaming, the silicone rubber foam was irradiated again to stabilize the foam structure and further improve its mechanical properties. The effects of irradiation dose before and after foaming, and the amount of blowing agents on the structure and properties of silicone rubber foam were studied. The experimental results show that with the increase of AC content, the average cell diameter of silicone rubber foam increases a little, the foam density decreases to a minimum value when AC content is 10 phr. With the increase of irradiation dose before foaming from 10 to 17.5 kGy, the cell nucleation density of silicone rubber foam increases, the average cell diameter decreases, and the foam density increases. With the increase of irradiation before foaming, the tensile strength, tensile modulus, and the elongation at break of the silicone rubber foam increase. Through irradiation crosslinking again after foaming, the foam density is decreased and the mechanical properties of silicone foam are further improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Radiation‐induced crosslinking of ultra high molecular weight polyethylene fibers by means of electron beams

Crosslinking of ultra high molecular weight polyethylene fibers (UHMW‐PE fibers) is investigated by means of electron beam irradiation. The structure and mechanical properties of the fibers in different irradiation atmospheres are discussed. The results show that the gel fraction and crosslinking density increase with the increase of absorbed dose. The swelling ratio and average molecular weight of crosslinked net decrease with the increase of absorbed dose. The relation between s + s^?1 of the UHMW‐PE fibers and reciprocal irradiation dose 1/R is obtained. The tensile strength and failure elongation decrease with the increase of absorbed dose, and the tensile modulus increases with the increase of absorbed dose. The samples are irradiated in air, vacuum, and acetylene atmospheres, separately. The radiation effects, such as crosslinking fraction and mechanical properties of UHMW‐PE fibers, are the most significant in acetylene atmosphere in comparison with in air and in vacuum. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1761–1764, 2005     

Radiation preparation of ultrafine carboxylated styrene–butadiene rubber powders and application for nylon 6 as an impact modifier

Ultrafine carboxylated styrene–butadiene rubber(CSBR) powders were prepared by using gamma irradiation and following spray‐drying method. The influences of dose rate, absorbed dose, and sensitizer content on the crosslinking density of CSBR latices were studied in detail. Then the ultrafine CSBR powders were used to toughen nylon 6. The toughness and thermal properties of nylon 6/CSBR blends were measured by using notched lzod impact test and differential scanning calorimetry and thermogravimetry, respectively. Results showed that the crosslinking density of CSBR increased with increasing of dose and sensitizer content, and it is independent on dose rate. The notched Izod impact strength of nylon 6 under room temperature increased after incorporation of irradiation crosslinked CSBR powders with appropriate crosslinking density. The morphology of higher impact nylon 6/CSBR blends indicated that the finer dispersion existed with dispersed particles of 150‐nm diameter. Fracture morphology of nylon 6/CSBR blend suggested that the shear yielding in matrix is the primary toughening mechanism for nylon 6/CSBR blends. The crystallinity of nylon 6/CSBR blends decreased slightly compared with pure nylon 6, whereas the addition of CSBR powders had little influence on the thermal stability of nylon 6. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3040–3046, 2002