magistrsko delo
Ksaver Meško (Author), Majda Sfiligoj-Smole (Mentor), Bojana Vončina (Co-mentor), Matjaž Denac (Co-mentor)

Abstract

V magistrski nalogi smo proučili vpliv modifikacije izotaktičnega polipropilena (iPP) s teksturiranimi PA6.6 multifilamentnimi vlakni na strukturo, morfologijo, mehanske lastnosti in dimenzijsko obstojnost iPP kompozita. Kompozitne vzorce iz izotaktičnega polipropilena s teksturiranimi PA6.6 multifilamentnimi vlakni (volumski delež multifilamentnih vlaken je znašal 2,5 %) smo pripravili v ekstruderju, ter jih še dodatno homogenizirali preko taline v Brabenderjevem gnetilniku. Tako pripravljene kompozite smo uporabil za izdelavo zahtevnejšega mehanskega sklopa, za kar smo uporabili postopek injekcijskega stiskanja pri dveh različnih režimih stiskanja. Priprava kompozitov in predelava uporabljenih materialov v končni proizvod je potekala tako v laboratorijskih, kakor tudi v realnih, industrijskih pogojih in na industrijski opremi, kar daje delu dodaten pomen. Kompozitni vzorci iz izotaktičnega polipropilena s teksturiranimi PA6.6 multifilamentnimi vlakni imajo heterogeno morfologijo, saj sta komponenti nezdružljivi zaradi razlike v polarnosti in razlike v temperaturi taljenja. Opazne so razlike v strukturi med jedrom in površino injekcijsko stiskanih vzorcev, saj relaksacija ter čas ohlajanja vplivata na oblikovanje nadmolekulske urejenosti. PA6.6 polnilo se v injekcijsko stiskanem izdelku izotropo porazdeli po celotnem volumnu. Prisotnost PA6.6 polnila vpliva na zmanjšanje razlike med strukturo površinskih plasti vzorcev, ki so v stiku z orodjem, in strukturo v jedru, kjer se talina počasneje ohlaja. Tako pripravljenim preizkušancem iz iPP in iPP kompozita s teksturiranimi PA6.6 multifilamentnimi vlakni smo določali strukturo, morfologijo, mehanske lastnosti (natezne lastnosti in udarno žilavost) ter dimenzijsko obstojnost. V okviru določanja strukture in morfologije smo izvajali meritve v jedru in na površini izdelka, pri čemer smo ugotavljali tudi vpliv uporabljenega naknadnega tlaka pri injekcijskem stiskanju. Mehanske lastnosti kompozitnih vzorcev smo določili pri nateznih ter udarnih obremenitvah pri sobni temperaturi. Young-ov modul (E), mejo plastičnosti (?y), raztezek na meji plastičnosti (?y) pretržno trdnost (?b) in raztezek pri pretrgu (?b) smo določili z nateznim preizkusom, udarno žilavost (ak) pa z lomnim preizkusom poCharpy-jevi metodi. Ugotovili smo, da dodatek polnila k iPP poviša vrednost E ter ak, zniža pa vrednost ?b ter ?b, vendar pa razlike v mehanskih lastnostih med kompozitnim in nemodificiranim iPP niso visoke, razen znižanja vrednosti ?b. Dodana PA6.6. multifilamentna vlakna pozitivno vplivajo tudi naizboljšanje dimenzijske stabilnosti vzorcev, kar pojasnjujemo z znižanjem notranjih napetosti v izdelku, ki so pogojene z orientacijo strukturnih gradnikov.

Keywords

izotaktični polipropilen;poliamidni 6.6 teksturiran multifilament;kompozitni material;injekcijsko stiskanje;dimenzijska stabilnost;tekstilne preiskave;

Data

Language: Slovenian
Year of publishing:
Source: Maribor
Typology: 2.09 - Master's Thesis
Organization: UM FS - Faculty of Mechanical Engineering
Publisher: [K. Meško]
UDC: 678.027.74
COBISS: 14143510 Link will open in a new window
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Other data

Secondary language: English
Secondary title: Reinforced study injection moulding composite with textured pa 6.6. multifilaments
Secondary abstract: Postgraduate work comprehend preparing binary heterogeneous composites of isotactic polypropylene (iPP) as matrikes and poliamid fibres (PA6.6) as filler of content 2,5 vol. %. Components were prepared by melt-mixing in Brabender kneading chamber. The extruded material was cooled down to room temperature and granulated. From formation material were produced a constriction pretentious connection element by injection moulding. Preparation and production process were running under industrial conditions. For characteristic comparison of finished products additional samples from the pure iPP were produced under the same technological conditions. The study includes reciprocal influence of components of heterogeneous binary composites, technological procedure and injection moulding production parameters. The heterogeneous binary composite structure was carried out by optical microscopy (OM), polarized optical microscopy (POM), scanning electronmicroscopy (SEM) and wide-angel X-ray diffraction (WAXD). This research had shown the presence of PA6.6 fibres which caused the heterogeneus structure. The composite components were incompatible, therefore immiscible as well as mechanical irreconcilable. It was proved that the PA6.6 filler had an influence on the specific formation process. PA filler - fibres with own largeness caused isotropic disposition in the complete volume, irrespective on specific melt flow. Reduction the difference among core-shell morphology was causing disorientation in volume of a product. Mechanical properties were determined at tensile and impact load at room temperature. Young moduls (E), yield stress (?y) and elongation at break (?b) were determined by tensiletesting, whereas notched impact strenght (ak) was determined according to Charpy impact test. Heterogeneous filler in iPP matrikes increased values of E and ak and decreased values of ?b and ?b. In polymer blends, the influences of PA fibres on mechanical properties are very similar, except the ?b where iPP/PA composites reflected lower values as iPP material. The improvement of E and ak which was achieved in iPP/PA6.6 composites was the result of filler disturbance in composites morfology because they interrupted tension and thermal forces. For construction polymer material had the most significant role relation between toughness and stiffness which presented relation between mentioned characteristics. Because inorganic fillers usually increase stiffness and at the same time decrease toughness is influence on theextensible component quite opposite. Measurement of mechanical properties iPP/PA6.6 comopsites proved that the filler influence is similar. Polymer products might show instabilities in dimensions. The injection moulding product were directly dependent on production method. Since polymers have time-dependent properties (viscoelasticity); as well as cooling under stress to the final temperature the final product preserves the shaping history and reacts to that by instability of dimensions and shape. Mold filling phase created oriented layers. Difference in oriented layers in injection molded products are undesirable for constructions elements because that is the cause for internal stresses. Added PA6.6 multifilaments fibres can also improve dimensional stability of samples, which can be explained by decreased inner tensions in products which are based on structual part orientation.
Secondary keywords: isotactic polypropylene;poliamide 6.6 textured multifilaments;composites;injection moulding;dimension stabilities;
URN: URN:SI:UM:
Type (COBISS): Master's thesis
Thesis comment: Univ. v Mariboru, Fak. za strojništvo
Pages: XV, 91 str.
Keywords (UDC): applied sciences;medicine;technology;uporabne znanosti;medicina;tehnika;various industries;trades and crafts;razne industrije;obrti in rokodelstva;industries based on macromolecular materials;rubber industry;plastics industry;industrija makromolekulskih snovi;industrija kavčuka;industrija umetnih snovi;
ID: 1011437