Primerjava lastnosti vodil za hmelj iz naravnih in sintetičnih materialov

Pustoslemšek, Tea (author), Demšar, Andrej (mentor), Čeh, Barbara (co-mentor)

Vodila (vrvice) se v hmeljarstvu uporabljajo kot opora pri rasti hmelja med rastno sezono. Namen diplomskega dela je bil primerjati različna vodila, ki se uporabljajo v hmeljarstvu, in preveriti njihovo učinkovitost. Cilj raziskave je bil ugotoviti, katero vodilo je najprimernejše za uporabo, ob upoštevanju lastnosti in cene. Vodila za raziskavo so bila izbrana na podlagi rezultatov ankete, izvedene med slovenskimi hmeljarji – preučili smo vodila, ki se uporabljajo v praksi oziroma so bila vsaj že preizkušana na eksperimentalnem posestvu Inštituta za hmeljarstvo in pivovarstvo Slovenije (IHPS). V teoretičnem delu diplomskega dela so predstavljene naslednje teme: zgodovina hmeljarstva in vodil, uporaba vodil (vrvic) v hmeljarstvu, vodila iz naravnih vlaken, vodila iz kemičnih vlaken iz naravnih polimerov ter vodila iz sintetičnih vlaken, prihodnost vodil ter odvoz in shranjevanje hmeljevine (biomasa, ki ostane po obiranju hmelja – listi in stebla, prepletena z vrvicami). V eksperimentalnem delu smo v praksi preizkusili in predstavili 5 hmeljarskih vodil (vrvic) različnega izvora in njihove lastnosti. Na vrvicah so bile pred obešanjem v hmeljišče (nove vrvice) in po staranju na njivi (vzorčeno konec rastne sezone hmelja) izvedene naslednje tekstilno-mehanske preiskave: struktura vrvic, zavoji, dolžinska masa ter natezne lastnosti. Rezultati so pokazali, da število zavojev ne vpliva na natezne lastnosti. Najboljše natezne lastnosti je imela vrvica iz regeneriranih celuloznih vlaken, vendar so se lastnosti te vrvice po staranju v hmeljišču močno poslabšale. Glede na specifikacije imajo vodila iz sintetičnih vlaken boljše lastnosti kot vodila iz naravnih vlaken. Vodila iz kemičnih vlaken iz naravnih polimerov imajo glede na specifikacije sintetičnih vlaken primerljive rezultate. Pri teh vodilih se je po staranju za malenkost zvišala specifična pretržna napetost, medtem ko se je pri drugih vodilih (iz naravnih ter iz sintetičnih vlaken) znižala. Primerjava nabavnih cen vodil pokaže, da so najdražja vodila iz naravnih vlaken, sledijo vodila iz kemičnih vlaken iz naravnih polimerov, najcenejša pa so vodila iz sintetičnih vlaken. Na podlagi primerjave lastnosti in trenutne cene vodil je bila za najbolj ustrezno vrvico izbrana vrvica iz polimlečne kisline (PLA).

• Language: Slovenian
• Keywords: hmeljarstvo, vodila, vlakna, natezne lastnosti, staranje, biorazgradljivost
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-115952
• Publication date in RUL: 01.05.2020

Secondary language

• Language: English
• Title: Comparison of twines, used in hop growing, made of natural and synthetic material

Abstract

Supports (twines) are used in hop production to assist hop growth during the growth season. The purpose of this thesis was to compare various supports used in hop growing and review their efficiency. The main aim of the research was to determine which supports are best suited for use, taking into account their qualities and price. The supports sampled were chosen based on the results of a survey done amongst Slovenian hop growers. These supports have already been in use or have at least been tested by the Slovenian Institute of Hop Research and Brewing (SIHRB) on their experimental property. The theoretical part of this thesis consists of the following: the history of hop growing and supports, the use of supports (twines) in hop production, supports from natural fibres, supports from chemical fibres from natural polymers, and supports from synthetic fibres, the future of supports, and the removal and storage of hop plant waste (i.e. biomass left after harvesting, composed of leaves and leaf stems mixed with twines). In the experimental part of the thesis, we tested and discussed five different hop supports (twines), distinguished by their origin and qualities. The following textile-mechanical tests were conducted on the twines before their application on the hop yard (i.e. fresh twines) and after aging in the field (samples were taken at the end of the growing season): twine structure, twists, linear mass density, and tensile properties. Results show that the number of twists does not influence the tensile properties of the twine. Twines from regenerated cellulose fibres have the best tensile properties; these properties, however, worsen significantly after the twine ages in the hop field. Based on their specifications, supports from synthetic fibres display better qualities than supports from natural fibres. Supports from chemical fibres from natural polymers show comparable results to supports from synthetic fibres. The former supports also show a slight increase in specific breaking tension after aging, whilst other supports (those from natural fibres and synthetic fibres) show a decrease in specific breaking tension. Comparing the purchase price of supports, the supports from natural fibres are the most expensive, followed by supports from chemical fibres from natural polymers, with supports from synthetic fibres being the lowest in price. Based on the comparison of the qualities and current prices of supports, twines made from polylactic acid (PLA) proved to be best suited for use.

• Keywords: hop production, supports, fibres, tensile properties, aging, biodegradability