▁collect or . ▁The ▁polym er ▁m elt ▁is ▁usually ▁produced ▁by ▁he ating ▁from ▁either ▁resistance ▁he ating , ▁circul ating ▁flu ids , ▁air ▁he ating ▁or ▁las ers . ▁ ▁Due ▁to ▁the ▁high ▁vis cos ity ▁of ▁polym er ▁mel ts , ▁the ▁fi ber ▁diam eters ▁are ▁usually ▁slightly ▁larger ▁than ▁those ▁obtained ▁from ▁solution ▁electro sp in ning . ▁The ▁fi ber ▁uniform ity ▁upon ▁ach ieving ▁stable ▁flow ▁rates ▁and ▁thermal ▁equilibrium , ▁tends ▁to ▁be ▁very ▁good . ▁The ▁wh ipping ▁inst ability ▁which ▁is ▁the ▁pre domin ant ▁stage ▁in ▁which ▁the ▁fi ber ▁is ▁stretch ed ▁for ▁spin ning ▁from ▁solutions ▁can ▁be ▁absent ▁from ▁the ▁process ▁due ▁to ▁the ▁low ▁m elt ▁conduct ivity ▁and ▁high ▁vis cos ity ▁of ▁the ▁m elt . ▁The ▁most ▁significant ▁factors ▁which ▁affect ▁the ▁fi ber ▁size ▁tend ▁to ▁be ▁the ▁feed ▁rate , ▁the ▁mole cular ▁weight ▁of ▁the ▁polym er ▁and ▁the ▁diameter ▁of ▁the ▁sp inner et . ▁F iber ▁sizes ▁r anging ▁from ▁~ 2 5 0   nm ▁to ▁several ▁hundreds ▁of ▁mic rom eters ▁have ▁been ▁created ▁thus ▁far ▁with ▁the ▁lower ▁sizes ▁being ▁achieved ▁using ▁low ▁mole cular ▁weight ▁polym ers . ▁ ▁History ▁In ▁the ▁late ▁ 1 6 th ▁century ▁William ▁Gilbert ▁set ▁out ▁to ▁describe ▁the ▁behavior ▁of ▁magnetic ▁and ▁electro static ▁phen omena . ▁He ▁observed ▁that ▁when ▁a ▁suit ably ▁elect r ically ▁charged ▁piece ▁of ▁am ber ▁was ▁brought ▁near ▁a ▁dro