Mechanical properties of modified HDPE by ionizing radiation after temperature load under and above the pure HDPE melting temperature

Mechanical p ope ies o modi ied HDPE by ionizing adia ion a e empe a u e load unde and abo e he pu e HDPE mel ing empe a u e Pa el S oklasek, Ales Mize aa Tomas Ba a Uni e si y in Zlin, nam. T.G. Masa yka 5555, 76001 Zlin, Czech Republic , Mi osla Manas, Da id Manas, Ma in Bedna ik and Vacla Janos ik Abs ac . Radia ion p ocessing o polyme s is a well-es ablished and economical comme cial me hod o p ecisely modi ying he p ope ies o polyme s, especially mechanical p ope ies. The mechanical p ope ies o modi ied HDPE samples by be a ays we e measu ed a he ambien empe a u e and a e empe a u e load unde and abo e he pu e HDPE mel ing empe a u e. The es ed samples showed signi ican changes o mechanical beha iou be o e and a e empe a u e load. F om his poin o iew, new applica ions could also be seen in a eas wi h se ice empe a u es highe han hei o me mel ing poin . Keywo ds: ensile s eng h, ha dness, adia ion c oss-linking, high densi y polye hylene, empe a u e load. 1 In oduc ion Polyme s belong o cons uc i e ma e ials which ind use a he mos indus y b anches. The ad an age is a low weigh oge he wi h he excellen mechanical p ope ies, e y good chemical esis ance and o he p ope ies, which assign hem o a ious applica ions. Disad an age is mainly low empe a u e s abili y which signi ican ly educes usage o hese polyme s. Radia ion p ocessing o polyme s in ol es ea men o polyme ma e ials wi h ionizing adia ion o modi y hei physical and chemical p ope ies o make p ope y imp o emen . The e o e, he use o ionising adia ion has ound a e y wide ange o applica ions in medicine, ag icul u e and indus y. Many scien is s ha e examined he issues o polyme adia ion c oss-linking. They disco e ed ha some o polyme ma e ials exposed o ionizing adia ion end o ei he imp o e o wo sen hei mechanical p ope ies. I depends on hei chemical s uc u e i polyme s c oss-link o deg ade p edominan ly [1 - 9]. Radia ion c oss-linking usually imp o es he mo-mechanical and mechanical p ope ies. E ec o adia ion c oss-linking signi ican ly imp o es mechanical beha io a e empe a u e load. Because o ha , ma e ials which belong o g oup o s anda d polyme s can be used in applica ions, which would be in e m o mechanical beha iou in ended only o cons uc i e he moplas ic polyme s. Hence mo e polyme ma e ials and a wide ange o i adia ion doses will be in es iga ed o con i m o deny hese indings. a Co esponding au ho : mize a@ ai.u b.cz In e na ional Con e ence on Inno a i e Ma e ial Science and Technology (IMST 2016) © 2016. The au ho s – Published by A lan is P ess 416 2 Expe imen al 2.1 Ma e ial As he basic polyme ma e ial was used high densi y polye hylene (DOW HDPE 25055E). An ARBURG All ounde 420C Ad ance Injec ion molding machine was used o sample p epa a ion, wi h he p ocessing condi ional o comply wi h he HDPE p oduce ’s ecommenda ions. 2.2 I adia ion o samples I adia ion o es ed LDPE polyme was pe o med wi h he kind help o BGS Ge many, in he BGS Wiehl plan using accele a ed elec ons wi h a dosage ange o 0 o 198kGy. 2.3 Sample empe a u e load Non-modi ica ed and modi ica ed samples o HDPE we e exposed empe a u e 110 °C and samples wi h he dosage o i adia ion highe han 99 kGy we e exposed empe a u e 180°C and 220 °C du ing 15 minu es, hen all hese samples we e cooled spon aneously o ambien empe a u e. 2.4 Used me hods o he es ing The ensile beha iou o empe a u e non-loaded and loaded samples o LDPE we e measu ed a he ambien . Tensile es was ca ied ou on ensile es machine ZWICK 1456 o HDPE acco ding o s anda d CSN EN ISO 527-1, 527-2 wi h used a e 50 mm/min. Tes da a was p ocessed by Tes Expe S anda d so wa e and E-modulus [MPa], ensile s eng h [MPa] and elonga ion a b eak [%] we e de e mined. Ha dness was measu ed using a HPE – D Be eiss ha dness es e ype, and he Sho e D Me hod. The shape and dimensions o he es ing samples we e in acco d wi h he CSN 621431 s anda d. 3 Resul s and discussion The ensile beha iou and ha dness o high densi y polye hylene, be o e and a e i adia ion, was s udied. Fo easie o e alua ion o he measu ed da a, and he compa ison o he i adia ed polyme wi h a non-i adia ed one, he changes o measu ed we e used on some g aphs. The p ope y o he non-i adia ed polyme had he alue o 100 %, while o he s we e exp essed in % as he a io o measu ed p ope y o i adia ed polyme s o he same p ope y o non-i adia ed polyme . 3.1 HDPE ensile es I adia ion a ec s he ensile beha iou o he HDPE was s udied a ambien empe a u e and a e empe a u e load. A e pe o ming he ensile es a ambien empe a u e h ee obse ed pa ame e s (E-modulus, ensile s eng h, and elonga ion a b eak) we e compa ed. The alue o non-i adia ed sample E-modulus was measu ed 1247 MPa a 23°C. As can be seen om igu e 1, he e was a sligh g ow h o he E-modulus wi h dose o i adia ion 33 kGy abou 3%. Howe e , E-modulus wi h he inc easing dose a e empe a u e load dec eases be ween 2 and 8 % in compa ison o non-i adia ed sample be o e empe a u e load. In e na ional Con e ence on Inno a i e Ma e ial Science and Technology (IMST 2016) © 2016. The au ho s – Published by A lan is P ess 417 Figu e 1. HDPE E-modulus. Figu e 2. HDPE ensile s eng h. The alue o non-i adia ed sample ensile s eng h was measu ed 25.8 MPa a 23 °C. As can be seen om igu e 2, he e was no a signi ican g ow h o he ensile s eng h wi h inc easing doses o i adia ion and a e empe a u e load. The alue o non-i adia ed sample elonga ion a b eak was measu ed 201 % a 23 °C. As can be seen om igu e 3, he e was a signi ican dec ease o he elonga ion a b eak wi h inc easing doses o i adia ion. The elonga ion a b eak ises abou 15 % a e i adia ion wi h a dosage o 33 kGy and empe a u e load a 110 °C in compa ison wi h non-i adia ed HDPE. Howe e , he elonga ion a b eak a e empe a u e load a 220 °C wi h a dosage o 198 kGy dec eases abou 50 % in compa ison wi h non-i adia ed HDPE be o e empe a u e load. In e na ional Con e ence on Inno a i e Ma e ial Science and Technology (IMST 2016) © 2016. The au ho s – Published by A lan is P ess 418 Figu e 3. HDPE elonga ion. 3.2 HDPE ha dness es I adia ion a ec s he ha dness o he HDPE was s udied a ambien empe a u e and a e empe a u e load. A e pe o ming he ha dness es a ambien empe a u e h ee obse ed pa ame e s (ha dness acco ding o Sho e D) we e compa ed. No signi ican changes o ha dness we e ound a e he i adia ion on he HDPE sample. A maximum inc ease o ha dness (i.e. abou 8%) was measu ed a e he i adia ion dosage o 99kGy. Highe doses o i adia ion had no signi ican e ec on he Sho e D Ha dness (Fig. 4). Ne e heless, he ha dness a e empe a u e load dec eases abou 10 % in compa ison wi hou empe a u e load HDPE. Figu e 4. HDPE ha dness. 4 Conclusions Expe imen s done in his p ojec showed ha i adia ion c oss-linking ma kedly a ec ed he mechanical p ope ies o he HDPE s udied. The highe he i adia ion dosage, he be e he mechanical beha iou o s udied polyme s is a he highe empe a u e. As can be seen om he es s esul s, he i adia ion c oss-linking sligh ly imp o es he HDPE ensile beha iou and ha dness. In e na ional Con e ence on Inno a i e Ma e ial Science and Technology (IMST 2016) © 2016. The au ho s – Published by A lan is P ess 419 I adia ion imp o es he he mal p ope ies o polyme . Tes ed polyme (HDPE) shows be e empe a u e s abili y a e i adia ion. Because o mel ing o i adia ed samples up o 99 kGy measu emen could no ha e been done. I adia ion signi ican ly ex ends he applica ion a ea o polyme s. The se ice empe a u e can be highe han he mel ing poin o no i adia ed polyme s. The esul s o he measu emen s o HDPE a e i adia ion showed signi ican changes o i s mechanical p ope ies. The E-modulus dec eases only abou 3 %, a e i adia ion wi h a dosage o 165 kGy a e empe a u e load a 220 °C in compa ison o non-load sample. The ensile s eng h is almos cons an be o e and a e empe a u e load. The elonga ion a b eak ises by 11 %, a e i adia ion wi h a dosage o 198 kGy and a e empe a u e load a 180 °C in compa ison o non-load sample. The ha dness is no changed a e i adia ion and empe a u e load. Howe e , a e y impo an poin is he imp o emen o he HDPE specimen empe a u e s abili y, a e i adia ion. Acknowledgmen s This pape is suppo ed by he in e nal g an o TBU in Zlin No. IGA/FT/2016/010 unded om he esou ces o speci ic uni e si y esea ch and by he Minis y o Educa ion, You h and Spo s o he Czech Republic wi hin he Na ional Sus ainabili y P og amme p ojec No.LO1303 (MSMT- 7778/2014) and also by he Eu opean Regional De elopmen Fund unde he p ojec CEBIA-Tech No. CZ.1.05/2.1.00/03.0089. Re e ences 1. J.G. D obny, Radia ion Technology o Polyme s, CRC P ess, 2010. 2. K. Makuuchi and S. Cheng, Radia ion P ocessing o Polyme Ma e ials and I s Indus ial Applica ions, John Wiley & Sons, 2012. 3. D.W. Clegg and A.A. Collye , I adia ion E ec on Polyme s, Else ie Science Publica ions, 1991. 4. R.L. Clough and S.W. Shalaby, I adia ion o Polyme s: Fundamen als and Technological Applica ions, Ame ican Chemical Socie y, 1996. 5. S. M. Tamboli e al., Indian J. Chem. Tech. 11 (2004) 853-864. 6. H. A. Khonakda e al., Radia . Phys. Chem. 75 (2006) 78-86. 7. S. Dadbin e al., J. Appl. Polym. Sci. 86 (2002) 1959-1969. 8. S. P. Hlango hi e al., Polym. Deg ad. S abil. 79 (2003) 53-59. 9. I. K upa e al., Polym. Deg ad. S abil. 73 (2001) 157-161. In e na ional Con e ence on Inno a i e Ma e ial Science and Technology (IMST 2016) © 2016. The au ho s – Published by A lan is P ess 420