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     

辐照交联聚丙烯发泡材料的制备工艺

运用辐照的方法提高聚丙烯的熔体强度,然后对其片材进行发泡.通过正交试验,研究辐照敏化剂含量、发泡剂含量和辐照剂量对试样拉伸强度的影响,确定了最佳工艺条件.讨论辐照敏化剂含量、发泡剂含量和辐照剂量对体系交联程度和发泡材料形态的的影响.分析表明:敏化剂舍量与辐照剂量相匹配时,达到适当的交联程度,可以得到发泡倍率高、泡孔尺寸均匀的发泡材料.     

乙烯-四氟乙烯共聚物的辐照交联及辐照敏化剂研究

简述了高分子辐照加工及其影响因素,详细综述了乙烯-四氟乙烯共聚物(F40)辐照交联研究,同时归类分析了F40辐照交联的辐照敏化剂合成及开发研究,并对F40的辐照交联开发做了相应的展望.     

聚氯乙烯交联技术及其应用的研究

以多官能团单体 T_(90)为敏化交联剂,选用辐照交联方法,研究了聚氯乙烯(PVC)交联的基本工艺因素、工艺参数及凝胶率对机械、电绝缘,抗老化等性能的影响,确定了 PVC 交联工艺技术;用此技术试生产的交联 PVC 黑色套管,可以耐250℃高温,热收缩率低,已用于彩色电视机生产中。     

化学交联聚丙烯的研究

本文通过测定交联聚丙烯的凝胶含量及流变性，研究了以Ｎ，Ｎ＇－间苯基双马来酰亚胺作为交联助剂的过氧化二异丙苯引发聚丙烯的交联反应，结果表明ＰＰ必须交联助剂的存在下才能发生交联反应，其交程序与引发剂，交联助剂的含量以及工艺条件有关。     

交联聚乙烯管国内外发展概况

介绍了交联聚乙烯(PE-X)及其管材的交联机理和产品特点.比较了过氧化物PE-X管、硅烷PE-X管、辐照PE-X管的生产工艺和产品优缺点.综述了PE-X管国内外近几年的发展、市场需求、生产以及专用料的开发应用情况,针对地暖管领域目前市场使用的PE-X管、耐热聚乙烯管、无规共聚聚丙烯管、聚1-丁烯管进行性能比较,阐述了P...     

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。     

EVA交联机理的研究

研究了过氧化二异丙苯(DCP)对乙烯-醋酸乙烯共聚物(EVA)交联的影响,分析交联过程的反应机理.对交联的EVA样品进行紫外光辐照,分析在该过程中所发生的反应,并研究加入紫外线吸收剂2-羟基-4-正辛氧基-二苯甲酮(UV-531)后,对交联EVA样品在紫外光辐照下交联的影响.     

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。     

Grafting of Hindered Amine Stabilizer in Poly(propylene) Films under γ‐Irradiation

Summary: In this paper, the grafting of a hindered amine stabilizer (HAS) is studied in isotactic poly(propylene) (PP) films under γ‐irradiation. The HAS used has a definite structure that combines a hindered amine functionality and a UV‐absorbing unit (benzylidene malonate ester group) detectable at 308 nm in the UV spectrum of PP film and 314 nm in chloroform. The stabilizer is added to the polymer at various concentration ratios: 0.1, 0.2, and 0.3 wt.‐%. The percentage of HAS grafting in the PP film at various additive concentrations is determined as a function of γ‐radiation dose in the range of 0–100 kGy by direct spectroscopic measurements through the absorption band of the stabilizer in the UV spectra of the PP film. The percentage of free HAS extracted with chloroform from the PP film versus the radiation dose is determined by UV spectroscopy for all the additive concentrations used. This study reveals that only 80% of the HAS is grafted on the 100 kGy irradiated PP matrix independent of the additive concentration used. However, the percentage of HAS grafted on PP films displays an exponential dependence on γ‐radiation dose. These results are consistent with the data obtained on the free HAS content. γ‐Irradiation grafting of HAS in the PP is accompanied by the oxidative degradation of the polymer substrate that is evaluated by increasing the carbonyl index and reducing significantly the oxidation induction time of the PP films.

The percentage of hindered amine stabilizer grafted to the PP film as a function of γ‐radiation dose.     

Enhanced Interfacial Adhesion of Bioflour‐Filled Poly(propylene) Biocomposites by Electron‐Beam Irradiation

Summary: The effect of electron‐beam (EB) irradiation on interfacial adhesion in bioflour (rice‐husk flour, RHF)‐filled poly(propylene) (PP) biocomposites in which either only the RHF had been EB irradiated or the whole biocomposite had been EB irradiated was examined at different EB‐irradiation doses. The tensile strengths of PP–RHF biocomposites with EB‐irradiated RHF and EB‐irradiated PP and PP–RHF biocomposites were slightly higher than those of the nonirradiated samples. The improved interfacial adhesion of PP–RHF biocomposites with EB radiated RHF and the EB‐irradiated PP–RHF biocomposites compared with the nonirradiated samples was confirmed by the morphological characteristics. In addition, the thermal stability of EB‐treated biocomposites was slightly higher than those of nonirradiated samples at the irradiation doses of 2 and 5 Mrad. However, at the high irradiation dose (30 Mrad), the tensile strengths of the biocomposites were slightly decreased by main‐chain scission (degradation) of PP and RHF. Attenuated total reflectance FT‐IR and X‐ray‐photoelectron‐spectroscopy findings confirmed this result by showing that that EB irradiation changed the functional groups of RHF, PP, and the biocomposites and improved the surface characteristics of the biocomposites. The thermal characteristics of the EB‐irradiated PP and biocomposites were investigated using differential scanning calorimetry. From the results, we concluded that use of low‐dose EB radiation increases the interfacial adhesion between matrix polymer and biofiller.

     

The Effect of γ‐Irradiation on the Structure and Properties of Poly(propylene)/Clay Nanocomposites

The oxidative degradation of PP/OMMT nanocomposites under γ‐irradiation was studied. Changes in structure and properties resulting from γ‐exposure in the range 0–100 kGy were investigated. The results were analyzed by comparing the influence of PP‐g‐MA and pristine OMMT on the oxidation kinetics of neat PP. γ‐Irradiation in the presence of air strongly degraded the properties of PP materials, particularly for radiation doses above 20 kGy. The rate of oxidative degradation of PP/OMMT/PP‐g‐MA nanocomposites was much faster than that of neat PP. This suggests that PP‐g‐MA and pristine OMMT components behave as oxidation catalysts, leading to the formation of free radicals in the polymer matrix.

     

Functionalization of Poly(propylene) Fabric with 4‐Vinylpyridine,N,N‐Dimethylacrylamide and Styrene by γ‐Radiation‐Induced Grafting in an Aqueous Environment

Summary: VP and co‐monomers DMAAm and ST were successfully grafted onto a PP fabric in an emulsion copolymerization process initiated by γ‐radiation. The radiation dose, concentration of VP, the ratio of VP/DMAAm and VP/ST in the reaction solution, and the reaction temperature dependent graft copolymerization were investigated. The order of dependence of the initial rate of grafting on the radiation dose was found to be in the range of 1.2 to 0.93 for VP; 0.84 to 0.70 for VP/DMAAm and for VP/ST was in the range of 0.59 to 0.41. The activation energy of the graft copolymer reaction was determined to be 40.18 J · mol^?1 for 0.464 mol · L^?1 VP. In the case of co‐monomer mixtures (VP/DMAAm: 0.464/0.5) the energy of activation was noticeably higher at 49.71 J · mol^?1 while for VP/ST (0.464/0.436) the activation energy was same as that of VP. XRD results showed that overall crystallinity significantly decreased with the increase of graft weight with a noticeable change in the chemical structure of the PP, indicating that the graft copolymer reaction was taking place both in the amorphous and crystalline regions of PP. A similar characteristic behavior was also obtained by DSC, which revealed the presence of an endotherm process in the range of 25 to 130 °C depending on the degree of grafting, attributed to the grafted chains of the monomer/co‐monomers. In order to determine the graft copolymer reaction of VP, DMAAm and ST onto the backbone of PP, the reaction products were characterized by FTIR spectroscopy. A good correlation was found between changes of crystallinity and level of graft copolymerization as determined by WAXRD and DSC.

Typical XRD traces of as‐received PP fabric (PPF) and grafted with VP (PPF‐g‐VP).     

The observation of PP/EVA blends in which isotactic PP was preradiated with different radiation absorbed doses

Isotactic polypropylene (PP) was preradiated by γ ray with different absorbed doses and subsequently blended with ethylene‐vinyl acetate (EVA) co‐polymer to prepare PP/EVA blends. The average molecular weight (M_n) of isotactic PP decreased with the increasing radiation absorbed dose, which indicated that high energy radiation of γ ray broke the isotactic long PP chains into shorter ones. The melt flow rate results evidenced that the processing ability of PP/EVA blends was continuously promoted with the increasing absorbed dose. The β crystal was obtained in the PP/EVA blends by the radiation method. The onset temperatures and peaks of crystallization of PP/EVA blends decreased slightly with the increasing radiation absorbed dose, while high energy radiation was inclined to enhance the crystallinity of PP/EVA blends. The Fourier transform infrared spectroscopy (FTIR) tests confirmed an interesting phenomenon that PP tended to move to the surface of the PP/EVA blends with the increasing radiation absorbed dose. Mechanical tests proved that the PP/EVA blends remained a comparative stable mechanical property under the absorbed dose of 30 kGy. The experimental results indicated that PP/EVA blend was a potential candidate for industrial applying. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45057.     

PP／EVA共混体系敏化辐射交联的研究

研究了在多官能团单体-三烯丙基异氰酸酯(TAIC)存在下,聚丙烯(PP)/乙烯-醋酸乙烯酯(EVA)共混体系的辐射交联、并应用凝胶量、力学性能等数据对其进行表征。结果表明,TAIC对PP/EVA共混体系的辐射交联的敏化作用显著,EVA对体系凝胶生成有正的协同作用,改善了TAIC在共混体系中的分布。敏化交联还改善了PP/EVA共混体系的相容性,增强了相间粘附,提高了其力学性能。     

紫外光辐照对不同结构聚丙烯的结构变化与力学性能的影响

对比了均聚级和共聚级聚丙烯的力学性能以及紫外辐照对其力学性能、红外光谱和X射线衍射的不同影响。结果显示,共聚级PP的冲击强度比均聚PP高得多,其抗紫外老化性能也比均聚PP优越;均聚PP和共聚PP经紫外辐照后在分子链上引入羰基,且引入量随辐照时间的延长而增加;紫外辐照可以使聚丙烯中不稳定的晶型发生转变,而且对老化后均聚PP和共聚PP的衍射峰强度产生不同的影响。     

Preparation and Characterization of Polycarbonate/Poly(propylene)/Attapulgite Ternary Nanocomposites with the Morphology of Encapsulation

Summary: Ternary nanocomposites based on polycarbonate (PC), poly(propylene) (PP), and attapulgite (AT) were prepared via the method of two‐step melt blending, by which the AT was blended with PP prior to compound with PC. Structure and properties of the ternary PC/PP/AT nanocomposites were investigated. The degradation of PC triggered by AT during direct blending process can be inhibited effectively by using two‐step melt blending. It was found that the morphology of encapsulation structure like sandbag was formed in PC matrix, where PP encapsulated AT fibrillar single crystals. DSC experiments showed that in PC/PP/AT ternary nanocomposites, AT had a strong heterophase nucleation effect on PP, resulting in the enhancement of crystallization degree and the crystallization temperature of PP. DMA and mechanical property results showed that the ternary nanocomposites exhibited good balanced toughness and stiffness.

TEM photograph of PC/PP/AT ternary nanocomposite.     

远红外丙纶纤维专用料的研制

选择粒径分布适中的远红外发射微粉，采用一种新型的工艺方法对微粉进行有效的表面处理，在保证远红外发射率的前提下．从根本上解决了微粉在聚丙烯中分散不均和超细粉结团的问题，使得专用料的可纺性大幅提高，既可用来生产短纤维，也可用于生产长纤维。     

Use of Monomethyl Itaconate Grafted Poly(propylene) (PP) and Ethylene Propylene Rubber (EPR) as Compatibilizers for PP/EPR Blends

The use of grafted poly(propylene) (PP) and a random copolymer of ethylene and propylene (EPR) with an itaconic acid derivative, monomethyl itaconate (MMI), as compatibilizer for PP/EPR blends was analyzed. The grafting reaction was performed at 190 °C in a Brabender Plasticorder. 2,5‐Dimethyl‐2,5‐bis(tert‐butylperoxy) hexane was the radical initiator for the functionalization of PP; dicumyl peroxide was used as the radical initiator for the modification of EPR. The obtained degree of grafting was 1.5% by weight for PP and 1.2% by weight for EPR. The compatibilizing effect of modified polymers on the processability, morphology, and mechanical and thermal properties of the blends was of interest. Compatibilization substantially improved the toughness and deformation with little effect on the tensile modulus and strength. Moreover, this effect was particularly evident when both polymeric phases were grafted. Regarding compatibilization, the viscosity of the blends increased due to the high interfacial adhesion. Morphological studies showed that the particle size of the rubbery phase was reduced and the dispersion in the matrix improved by compatibilization. The grafted polymers behaved as nucleating agents, accelerating the PP crystallization.

Change in complex viscosity with angular frequency at 180 °C for unmodified and MMI‐functionalized PP/EPR (70/30) blends.