Desigualdades sociais nas concepções dos professores e estudantes do PROEJA no Instituto Federal de Educação, Ciência e Tecnologia do Sertão Pernambucano - Campus Petrolina-PE

Este trabalho apresenta resultados de uma pesquisa realizada no IFSERTÃO - Instituto Federal de Educação, Ciência e Tecnologia do Sertão Pernambucano a respeito das desigualdades sociais nas concepções dos professores e estudantes do PROEJA. Teve como objetivo analisar e compreender os sentidos produzidos pelos sujeitos da pesquisa sobre as desigualdades sociais e suas perspectivas de superação, considerando seu histórico e seus aspectos atuais. Foi organizado epistemologicamente numa abordagem de pesquisa qualitativa a partir do ponto de vista metodológico do estudo de caso do tipo descritivo e analítico com entrevistas e análise do documento Base do Programa institucionalizado pelo MEC, buscando identificar as aproximações ou distanciamentos entre as concepções dos entrevistados com a proposta do material institucional no que diz respeito às perspectivas de superação das desigualdades no contexto da EJA. O problema da pesquisa foi formulado mediante o seguinte questionamento: Como as desigualdades sociais se apresentam nas concepções dos professores e estudantes do programa e quais suas perspectivas de superação? Para estudo do problema, procedeu-se à imersão no campo empírico da pesquisa com abordagens e utilização de um roteiro de entrevistas previamente formulado, incluiu-se a leitura flutuante do material coletado e as vozes dos entrevistados foram gravadas, transcritas, lidas e analisadas, buscando a captação do sentido atribuído pelos sujeitos a respeito das desigualdades sociais. Mediante essa trajetória, identificou-se, nas concepções dos sujeitos da pesquisa, que o trabalho se apresenta como centralidade no que se refere às manifestações das desigualdades sociais no contexto da EJA/PROEJA, bem como suas diferentes feições na lógica do sistema capitalista no que se refere a educar para a empregabilidade atendendo às exigências do capital. Assim, considerando que, historicamente, a EJA é uma modalidade de ensino que vem sendo ofertada para sujeitos que tiveram seus percursos escolares interrompidos pela condição de trabalhadores, esse tema se configura como estudo de grande relevância no contexto das políticas de Educação de Jovens e Adultos trabalhadores.

用NMR、FT-IR、DSC和AFM的方法研究PP-b-PE的结构与性能

聚丙烯是一种优异的高分子材料，但其低温抗冲击性能欠佳，因而限制了其应用范围。采用PP与PE嵌段共聚来改善PP的抗冲击性能是世界上目前行之有效的方法，因而引起人们的重视。由于聚丙烯嵌段共聚物（PP-b-PE）是由多组分组成的复杂体系，对其组成和链的结构仍不十分清楚。因此，本工作选取国外（6组）和国内（5组）共计11组PP-b-PE样品，分别对其结构、性能及其影响因素进行了研究，为实际应用提供了依据。为了保证能将PP-b-PE中的橡胶成分抽提出来，先将PP-b-PE样品用二甲苯溶解，之后加入甲醇沉淀、过滤、干燥，最后用正庚烷抽提，使得PP-b-PE样品中正庚烷的不可溶物与可溶物完全分离。其中，可溶物即为橡胶，不可溶物为塑料。再利用高温核磁共振谱仪（NMR）、示差扫描量热仪（DSC）和傅立汗卜变换红外谱仪（FT-IR）等先进的分析技术手段进行结构分析，并用原子力显微镜（AFM）观察生产过程中样品的形貌。实验和分析结果表明：在正庚烷可溶物中含有低熔点的聚丙烯和嵌段长度不同且能结晶的聚乙烯；并且还含有属于乙丙无规共聚物橡胶部分的n值小于4的（-CH2-）n结构，以及嵌有结晶性的丙烯和乙烯链节。正庚烷的不可溶物主要为聚丙烯，及少量聚乙烯。对于不同物性的PP-b-PE而言，正庚烷不可溶物决定了其刚性，正庚烷可溶物决定了其韧性，并由其粘度比决定了橡胶在聚丙烯中的分布情况。用AFM来研究PP-b-PE中的橡胶颗粒的分布情况是非常好的分析方法。PP-b-PE样品中橡胶的含量及其组成成分将对PP-b-PE的性能产生很大的影响。国内用浆液法生产的PP-b-PE样品中橡胶含量相对于用液一气相法和气相法生产的要少，但在其正庚烷不可溶物中含有较多的乙烯。从而可以用控制乙烯的含量来改善其抗冲击性能，这是浆液法与液一气相法和气相法的最大区别。液一气相法和气相法生产的PP-b-PE样品中的正庚烷可溶物的含量和结构十分接近。结果表明，本文采用多种不同的先进的分析方法和实验手段对PP-b-PE的结构与性能的研究是一条有效可行的实验途径。

“PP-PE”聚合合金结构与性能的关系及PP/HDPE共混体系增容改性的新途径

试图澄清“PP-PE”结构与性能的关系，并以此为指导寻求增容改性PP/HDPE体系的新途径是本工作的主要内容。在本工作中，考虑到分子量、EPC组分和共混均匀性因素之后发现，“PP-PE”与相同条件下合成的均聚物样品构成的共混物之间在应力-应变行为、抗冲击性能和动态力学行为上并没有明显差别。在结合文献中有关现象详尽讨论了关于活性链寿命报导值和“（PP-PE）_(200)"的C~(13)NMR谱支持嵌段结构观点的可靠性之后，得到的结论是，现有实验现象不中以证明“PP-PE”具有嵌段结构，尽管四十年来这一观点已被普遍接受。通过TEM观察到，“PP-PE”与PP/HMWPE共混物结晶结构相同，“PP-PE”中的PE部分明显具有HMWPE的片晶特征，应力-应变和SEM实验的结果显示，“PP-PE”与HMWPE具有完全相同的增容PP/HDPE的作用。结合有关共混物结构和性能的实验结果，发现“PP-PE”主要是一个共混物，其中的HMWPE和EPC组分是决定其性能行为的主要因素。尽管在理论和实验上都已确认，分子量的增大不利于共混物组分间的相容，但通过应力-应变实验和形态结构的观察发现，虽然均聚物HMWPE的加入使PP/HDPE体系中PE组分平均分子量增大，但是体系中分散相尺寸却随HMWPE含量的增加大幅度减小，力学性能全面提高。HMWPE这种同接枝和嵌段共聚相似的增容作用既不能用“相似相容”，也不能用所谓“特殊相互作用”来阐明。为此，在本工作中提出了一个新的增容机制——“缠结作用”。应力-应变实验表明，PP/HMWPE体系的力学性能明显优于PP/HDPE体系。前者强度和断裂伸长率都高于后者，其差别尤以断裂伸长率为甚，而模量相差不大。SEM形态结构的观察发现，虽然PP/HDPE体系中的分散相尺寸随其量的增加而增大，并且界面清晰，但PP/HMWPE中的缠结作用使得组分间界面模糊，甚至消失。这种较强的组分间相互作用使得材料由脆性断裂转变为韧性断裂。PP/HMWPE的性能特点进一步证实了非理想换气条件下制备的“PP-PE”结构与性能的关系。

PE文件隐型加壳技术的研究与实现

通过对PE(portable executable)文件格式的了解,编写PE分析工具对文件内部结构进行分析。详细介绍了对PE可执行文件加壳的全过程,在此过程中巧妙地使用MD5、CRC32等成熟的hash算法及防API断点跟踪等多种反破解技术,并采用自动隐藏加密方案,大大地提高了软件的保护力度。

The influence of variant PE-b-PEO segments on physical properties of LLDPE graft copolymers

A method was adopted to fix a series of polymers of PE-b-PEO with different PEO/PE segments on the chains of LLDPE. Maleic anhydride (MA) reacting with hydroxyl group of PE-b-PEO (mPE-b-PEO) was used as the intermediate. The structures of intermediates and graft copolymers were approved by H-1 NMR and FTIR. XPS analysis revealed a great amount of oxygen on the surface of grafted copolymers although the end group of PEO was fixed on the LLDPE chains through MA. Thermal properties of the graft copolymers as determined by differential scanning calorimetry (DSC) showed that PE segments in the grafted monomers could promote the heterogeneous nucleation of the polymer, increase T., and crystal growth rate.

(PE-g-PB-g-PA6)接枝共聚物中PA6链段结晶行为研究

采用选择性溶剂交替抽提的方法提纯在PE-g-PB-g-MA/PA6共混物中原位生成的接枝共聚物PE-g-PB-g-PA6,通过TEM﹑XPS﹑XRD﹑DSC等方法研究了该接枝共聚物的形貌与结晶行为。结果表明,PA6链段的结晶受到相形貌和分子结构的限制,扩散速度降低,导致在通常的结晶速率条件下(10℃/min)结晶不完善。

采用新萃取方法的PP-b-PE的研究

采用独特的二次溶解和沉淀的萃取方法,将PP b PE中的不可溶物与可溶物分离,并通过1 3C NMR,DSC,FT IR进行结构与性能的研究

PP/TAIC/PE共混体系的辐射增强相界面反应研究

研究了PP/TAIC(三烯丙基异腈脲酸酯)/PE共混体系的辐射增强相界面反应。应用SEM、DDV对共混体系的形态结构和相容性进行了表征,发现多官能团单体TAIC对PP/PE体系有较好的辐射增强作用,共混物的力学性能得到改善。

Effect of lamellar thickness on the epitaxial crystallization of PE on oriented iPP films

The effects of lamellar thickness on the epitaxial crystallization of polyethylene on the oriented isotatic polypropylene have been studied by means of transmission electron microscopy. The results obtained from the bright field electron microscopy and electron diffraction show that the epitaxial orientation of the PE crystals on the iPP substrate depends not only on the thickness of the oriented iPP lamellae, but also on the lamellar thickness of PE crystals. No epitaxial orientation relationship between PE crystal and iPP substrate can be found, when the PE crystals are thicker than the lamellar thickness of iPP along the matching direction. This suggests, that the epitaxial nucleation of PE in the PE/iPP epitaxial system is controlled not only by the chain-row matching, but also by a secondary nucleation process.

辐射增强PP/TAIC(TMPTMA)/PE共混体系相界面反应的研究——(Ⅰ)多官能团单体对形态结构及力学性能的影响

本研究中采用三烯丙基异腈脲酸酯(TAIC)和三羟甲基丙烷三甲基丙烯酸酯(TMPTMA)为PP/PE共混体系的多官能团单体。研究了辐照剂量,多官能团单体种类和多官能团单体用量对共混物形态结构及力学性能的影响。发现TAIC及TMPTMA对PP/PE体系有较好的增容作用,共混物具有好的相容性,力学性能得到改善。

MODIFICATION OF PP/HDPE BLENDS BY PP-PE SEQUENTIAL POLYMERIZATION PRODUCT

The morphology and mechanical properties of polypropylene/high-density polyethylene (PP/HDPE) blends in a wide range of compositions modified by a sequential Ziegler-Natta polymerization product (PP-PE) have been investigated. PP-PE contains multiple components such as PP, ethylene-propylene copolymer (EPC), and high molecular weight polyethylene (HMWPE). The effects of PP-PE on the mechanical properties and morphology of the PP/HDPE blends are the aggregative results of all its individual components. Addition of PP-PE to the blends not only improved the tensile strength of the blends, but the elongation at break increased linearly while the moduli were nearly unchanged. Morphological studies show that the adhesion between the two phases in all the blends of different compositions is enhanced and the dispersed domain sizes of the blends are reduced monotonously with the increment of the content of PP-PE. PP-PE has been demonstrated to be a more effective compatibilizer than EPC. Based on these results, it can be concluded that the tensile strength of the blends depends most on the adhesion between the two phases and the elongation at break depends most on the domain size of the dispersed component. (C) 1995 John Wiley & Sons, Inc.

EFFECT OF ETHYLENE-PROPYLENE COPOLYMER WITH RESIDUAL PE CRYSTALLINITY ON MECHANICAL-PROPERTIES AND MORPHOLOGY OF PP/HDPE BLENDS

Morphology and mechanical properties of polypropylene (PP)/high density polyethylene (HDPE) blends modified by ethylene-propylene copolymers (EPC) with residual PE crystallinity were investigated. The EPC showed different interfacial behavior in PP/HDPE blends of different compositions. A 25/75 blend of PP/HDPE (weight ratio) showed improved tensile strength and elongation at break at low EPC content (5 wt %). For the PP/HDPE = 50/50 blend, the presence of the EPC component tended to make the PP dispersed phase structure transform into a cocontinuous one, probably caused by improved viscosity matching of the two components. Both tensile strength and elongation at break were improved at EPC content of 5 wt %. For PP/HDPE 75/25 blends, the much smaller dispersed HDPE phase and significantly improved elongation at break resulted from compatibilization by EPC copolymers. (C) 1995 John Wiley & Sons, Inc.

PE-MAH的合成及其对PE/NBR的增容作用

聚乙烯(PE)、马来酸酐(MAH)和过氧化二异丙苯(DCP)在溶液中反应,其产物经多次纯化和红外光谱分析证明,MAH以化学键连接到PE分子链上,接枝率达0.5MAH/100E,即相当于平均每个PE上接枝有10个MAH。用不同接枝率的聚乙烯接枝马来酸酐共聚物(PE-MAH)作为极性差别较大的PE和丁腈橡胶(NBR)的相容剂,分别研究其接枝率和用量对共混物的拉伸强度和低温冲击强度的影响,结果发现:PE-MAH增加了PE/NBR的相容性。低温脆断面的扫描电子显微镜观察清楚地反映出PE-MAH的增容作用。本文还提出了增容模型。