<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31373519</termId><termName>polyolefin</termName><termType>PT</termType><termNote><![CDATA[ Refers to any polymerized olefin. Polypropylene and polyethylene are the two most common polyolefins.  ]]></termNote><termCreatedDate>2026-03-30 20:40:43</termCreatedDate><relation><relationType>UF</relationType><termId>31373520</termId><termName>polyolefins</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31343235</termId><termName>polymers</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31370895</termId><termName>polyethylene</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31370898</termId><termName>polypropylene</termName><termType>PT</termType></relation></term>  </Zthes>