Shanghai Daoqin Plastics Co., Ltd.

         aliphatic polyamide (PA) due to has amine and 羰基, easy and water separation formed hydrogen 键, therefore to various material in use easy water, generate increase 塑效应, 导致材 material 体积膨胀, modulus decline, in force function lower obvious creep.

         poly caprolactam and poly adipic acid hexamethylenediamine （ nylon 6 and nylon 66 ） is most commonly used polyamide (PA) material , it most high can from wet gas in absorption quality separation 数10% water separation, in generally wet degree ring lower can absorption quality separation 数2% to 4% water separation, multiple force property can 变化.

         nylon 6 and nylon 66 两 types material in 本文讨论 scope/range inner difference very small, nylon 6 /66. summary about/regarding nylon 6 /66吸 water mechanism and improvement its wet property research.

        （一） water separation for nylon 6 /66 property effect/influence

         nylon 6 /66吸 water rear, multiple property 质发生变化, but also many property 质 改变 and water amount has 关系.

        1, crystallization degree and structure

         for nylon 6 /66 晶体学 research 发现, nylon 6 /66都 is semi crystallization property material, molding rear has and non 晶区. in 晶区, separation 子链呈平面锯齿构象, through amine in and between formed hydrogen 键. in non 晶区, separation 子链构象呈 random 状, large more amine has versus function formed hydrogen 键, 呈“自由”状态, troubleshooting less 数区域形 formed local hydrogen 键.

        早期 research in, nylon crystallization degree through density 估算. nylon 6 /66 density ratio water large, water rear, this types material density upper rise, crystallization degree upper rise. tensile orientation nylon 6 /66材 material has separation γ-晶. research 发现, water rear nylon material γ-晶 ratio/proportion decrease/reduce, more stability α-晶 ratio/proportion increase large.

        2, force property can and separation 子运动

         nylon water rear in force property can upper very obvious. most main/primary is hardness, modulus and tensile strength decline, 屈服点 reduce, impact strong/high degree increase.

         nylon 6 /66 separation 子运动 research has magnetic 共振, force 学松弛 and dielectric loss and other methods, research nylon 6 /66材 material water front rear 转变发现, its 玻璃化转变 temperature degree (Tg) for water separation comparison 敏感, water rear, Tg large decline. 例如, nylon 6 water content is 0.35%w/w时Tg=94℃, 10.33%w/w时Tg=-6℃; drying nylon 66 Tg=78℃, water amount is 11%w/w时Tg=40℃. meanwhile 发现, Tg随吸 water amount increase decline process tool has stage/phase property. decline speed;当吸 water quality separation ultra- 一定 value rear, decline slow.

         comprehensive 各文献报道, 该临界 value in 2%~4%. nylon 6 /66 also in relatively low temperature degree lower performance β and γ转变, its in β转变 in wet sample in to, its strong/high degree 随 吸 water amount increase increase. has research also 发现, β转变峰 strong/high degree increase 伴随 γ转变峰 decrease/reduce, 并呈现 similar Tg stage/phase property.

         above phenomenon table/sheet similar 塑化 效果, however testing temperature degree 进一步 reduce, ultra- certain temperature degree rear, water separation in nylon 6 /66材 material in function versus 反, similar crosslinked hard 化. this temperature degree specific value in different in versus relatively large, has 人提出 this and force testing frequency rate, sample orientation degree and other conditions different has 关.

         nylon in long to small 于屈服点 应 force function rear, 会发生 hard 化, this type of 效果称 is “应 force aging ”(stress aging). in water rear, force aging speed rate add fast.

        3, dimensions 变化

         nylon 6 /66吸 water rear will 发生膨胀. 膨胀时, material dimensions and water amount 变化并不完 full 同步. nylon 6 fiber 随 吸 water amount 变化膨胀先 fast rear slow;而 nylon 6 film versus 反. tensile orientation sample, tool has toward property. in tensile orientation direction upper relatively obvious.

         research 发现, nylon 6 /66 in tensile function lower, its in separation hydrogen orientation tensile direction 靠拢, therefore is, nylon 6 /66吸 water in separation hydrogen direction upper comparison obvious.

        4, hot type methods

         nylon 6 /66 fiber production in has wet hot type and dry hot type types methods. research 发现, in crystallization degree same lower, dry hot type sample water amount ratio wet hot type less. wet hot type sample color property can relatively good.

        （二） nylon 6 /66吸 water mechanism

         summary research, currently basic is water separation 子 进入 nylon 6 /66 non 晶区域, water rear separation active property increase, 起塑化 function. this is upper to type 转变, Tg decline, new and other phenomenon causes.

        针 for Tg and other property 质随吸 water amount increase 而变化 process separation property phenomenon, Puffr and Šebenda提出 nylon 6 /66 separation water mechanism, by a large amount of 实验结果支持.

        该 mechanism is, water separation 子进入 nylon 6 /66无定形区, excellent 先以图 in 1 形式结 combined (紧密结 combined, tightly bound), water separation 子继续 increase more 时, 出现如图 in 2 示 结 combined 形式(松 dispersion combined, loosely bound), more more water separation will in separation 子间隙 in through water separation between hydrogen 键进一步堆积(clustering, in 3 示).

         upper to nylon 6 /66 in force 学松弛, electrical 松弛以 and force aging and other property 质随吸 water amount separation 段效应, positive is P-Š separation water mechanism 体现. in fatigue cracks long and fracture can and other property upper 也发现 随吸 water amount separation 段效应, can use P-Š mechanism understanding 释. meanwhile, wide 线NMR absorption and time 也发现 nylon 6 /66 absorption water separation in has separation tool has can active property, its in has combined degree different type water separation 子. positive electronics lifespan research table/sheet nylon 自由体积随吸 water amount increase decline rear upper rise, positive good and P-Š mechanism versus combined.

         for nylon water 理论描述 can use Flory-Huggins方程 or Zimm方程 描述(Zimm方程 is Flory-Huggins方程 development). will this and 实验结果 versus comparison 结果均支持 P-Š两步吸 water mechanism. another, through separation 子模拟 methods 也支持 this mechanism.

        （三） solution nylon 6 /66吸 water issues methods

        由 above can 知道, water for nylon 6 /66材 material 塑化效果 very obvious, but also in 初始吸 water stage/phase most 敏感. maintain drying ring ensure nylon 6 /66材 material property can comparison difficult. solution nylon 6 /66吸 water issues has type methods, is through reduce water amount decrease/reduce water separation for its property can effect/influence; is through improve/increase nylon 6 /66 related property can, can 抵消吸 water rear for nylon 6 /66 property can effect/influence.

        1, blending and composite/compounding

        添 add aldehyde resin and polyethylene (PE) 基苯酚 and other resin can decrease/reduce nylon 6 /66 吸 water amount, improve/increase its Tg, meanwhile for Tm effect/influence relatively small.

         research 发现, add type material main/primary in nylon 6 /66 无定形区域. for/regarding type material this type of 效果, research is this understanding 释: water therefore can bad nylon 6 /66 in already formed hydrogen and or amine formed new hydrogen 键, is is water separation and or amine formed hydrogen trend ratio between need high. and 羰基形 formed hydrogen trend ratio water separation more high, add type material rear, 酚基占据 nylon 6 /66 in and amine 基, its 含 苯 ring generate retardant 效应, retardant water separation 子 进入. through and other temperature 吸附实验, SAXS and separation 子模拟 methods 都支持 this type of understanding 释.

        添 add amine polyether (Blox), polyester or polyamide (PA) can decrease/reduce nylon 6 /66 吸 water amount. nylon 6 /66 and other polymer/macromolecule (如PP, PS, PC, ABS and other) blending generally can decrease slow water speed degree, can reduce water amount. meanwhile if versus property good, also 会牺牲 force property can.

        添 add machine nano pellets has 一定 效果. polyamide (PA) /层状 silicon acid salt nano composite/compounding material can large improve/increase force property can, heat deflection temperature (HDT), retardant property and flame retardant 效果, meanwhile add has machine 蒙脱土 polyamide (PA) /层状 silicon acid salt nano composite/compounding material can reduce water speed degree. 当蒙脱土 添 add to amount 时(usually large 于4%), can reduce nylon balanced water absorption. this is due to 蒙脱土做 is types nucleating agent, can improve/increase nylon crystallization degree, this its in 无定形区就变 small, from reduce nylon water amount.

         above nano composite/compounding material methods in decrease slow water speed degree, reduce water amount meanwhile, in very large degree upper also improvement nylon 6 /66因吸 water belt/tape defect rear 果. nylon 蒙脱土 nano composite/compounding material water rear, force property can decline and dimensions need small pure nylon. 另一方面, upper use this blending and machine nano composite/compounding in force property can upper obtain improvement, 如Tg, modulus improve/increase and other and other, 就算吸 water rear force property can has 回落, 回落 幅 degree 也远远 small add 入蒙脱土 rear increase degree. right is different content 蒙脱土 nylon 6 材 material, 放置一段 time rear flexural modulus 发生 变化, from in can 看出, make is 2%蒙脱土 添 add amount, in to saturated and water absorption rear, flexural modulus high pure nylon 6 very more.

         also has through will nylon 6 /66 and wet property relatively low, force strong/high degree relatively high nylon 11 bonding formed composite/compounding material, due to nylon 11 支架 or made function, water rear can maintain dimensions and force strong/high degree.

        2, crosslinked

         nylon 6 /66 crosslinked rear force property can is 常规, 即Tg upper rise, rigid property and property reinforcement. is about/regarding crosslinked rear water amount or water separation for material property can effect/influence very less, to 一篇报道称 its crosslinked rear nylon 6 吸 water amount has decrease/reduce.

        3, surface modified

         through for nylon 6 /66材 material surface hydrophobic water modified can decrease/reduce water amount. 例如, through surface grafting fluorine polymer or in surface formed tool has structure ultra- hydrophobic water 层. add amine polyether (Blox), polyester or polyamide (PA) can decrease/reduce nylon 6 /66 吸 water amount.