本文關(guān)鍵詞： MuCell 聚丙烯 微孔發(fā)泡 復(fù)合材料 力學(xué)性能 泡孔形貌　出處：《鄭州大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：聚丙烯(PP)發(fā)泡材料具有優(yōu)良的力學(xué)性能、較好的環(huán)境適應(yīng)性及耐熱性,廣泛應(yīng)用于車輛和航空航天等領(lǐng)域。然而,PP屬于半結(jié)晶聚合物,熔體強(qiáng)度較差,不利于均勻細(xì)密泡孔結(jié)構(gòu)的形成,而且其沖擊韌性較低,限制了PP微孔發(fā)泡材料的應(yīng)用。為優(yōu)化PP微孔發(fā)泡材料的泡孔形貌和力學(xué)性能,擴(kuò)展PP微孔發(fā)泡材料的應(yīng)用領(lǐng)域,本文基于MuCell微孔注塑成型技術(shù)進(jìn)行了如下研究:首先,采用單因素實驗法,研究了熔體溫度、注射速度、背壓和超臨界流體(SCF)含量等微孔注塑成型工藝條件對純PP微孔發(fā)泡材料發(fā)泡行為(泡孔尺寸和泡孔密度)和力學(xué)性能(拉伸、沖擊和彎曲強(qiáng)度)的影響,結(jié)果表明,在減重均為10%的前提下,純PP發(fā)泡試樣相同位置處的表觀密度在不同工藝組合下沒有明顯變化,充填近端均維持在0.775g/cm3左右,而充填遠(yuǎn)端在0.65-0.69g/cm3之間。隨熔體溫度升高,泡孔尺寸有先增后減的趨勢,泡孔密度則呈現(xiàn)相反規(guī)律,充填遠(yuǎn)端泡孔密度普遍高于充填近端。隨著注射速度和背壓的增加,充填近端和遠(yuǎn)端的泡孔尺寸均有減小的趨勢,而泡孔數(shù)量會有所增加;隨著SCF含量的提高,泡孔尺寸明顯降低,泡孔密度有增大的趨勢。不同工藝條件下,未發(fā)泡試樣的拉伸強(qiáng)度均保持在30MPa左右,發(fā)泡試樣的拉伸強(qiáng)度在16-19 MPa之間,相對于未發(fā)泡試樣,發(fā)泡試樣拉伸強(qiáng)度下降比例可達(dá)36%-45%。發(fā)泡試樣和未發(fā)泡試樣的缺口沖擊強(qiáng)度和彎曲強(qiáng)度分別維持在3 KJ/m2左右和31-34.3MPa之間,且發(fā)泡試樣的沖擊強(qiáng)度和彎曲強(qiáng)度一般大于未發(fā)泡試樣。而后研究了POE、滑石粉對于PP復(fù)合微孔發(fā)泡材料發(fā)泡行為和力學(xué)性能的影響。加入POE后,PP/POE共混物的粘度增大,熔體流動速率下降,PP的熔體強(qiáng)度得到提升,改善了PP的發(fā)泡效果。隨POE含量的提高,共混物發(fā)泡試樣的泡孔平均直徑呈先降低后增大的趨勢,而泡孔密度呈相反趨勢,當(dāng)POE含量為15%時,泡孔的平均直徑降至73.8μm,泡孔密度則達(dá)到13.1×105個/cm3,是其它組分下泡孔密度的5-7倍,且泡孔分布均勻,無明顯合并和塌陷。發(fā)泡和未發(fā)泡試樣的拉伸強(qiáng)度和彎曲強(qiáng)度均呈連續(xù)下降趨勢,發(fā)泡試樣的沖擊強(qiáng)度在POE含量為25%時達(dá)到最大值18.24 MPa,而未添加POE時發(fā)泡試樣的沖擊強(qiáng)度僅有3.08 MPa。對于PP/POE/滑石粉共混物,滑石粉的加入對PP/POE共混物發(fā)泡效果的改善作用有限,但其整體發(fā)泡效果仍好于純PP,在滑石粉含量為10%時,泡孔平均直徑為142.7μm,泡孔密度為1.33×105個/cm3,泡孔形貌優(yōu)于其它組分。此時發(fā)泡試樣的拉伸強(qiáng)度達(dá)到最大值17.5MPa,隨滑石粉含量提高,共混物發(fā)泡和未發(fā)泡試樣的彎曲強(qiáng)度則有較大提升,分別可達(dá)33.57MPa和34.44MPa,而沖擊強(qiáng)度均持續(xù)下降,但仍大于純PP發(fā)泡試樣的沖擊強(qiáng)度。
[Abstract]:Polypropylene (PP) foamed materials have excellent mechanical properties, good environmental adaptability and heat resistance, and are widely used in vehicle, aerospace and other fields. However, PP is a semi-crystalline polymer. The poor melt strength is not conducive to the formation of homogeneous and dense foam structure, and its impact toughness is low, which limits the application of PP microcellular foaming materials. In order to optimize the morphology and mechanical properties of PP microporous foaming materials. In order to expand the application field of PP microcellular foaming material, the following research was done based on MuCell micropore injection molding technology: firstly, the melt temperature and injection rate were studied by single factor experiment method. The effects of back pressure and SCF content on the foaming behavior (size and density) and mechanical properties (tensile) of pure PP microcellular foamed materials were investigated. The results showed that the apparent density of pure PP foamed specimen at the same position had no obvious change under the condition of weight loss of 10%. The proximal end of filling was maintained at about 0.775g / cm ~ 3, while the distal end of filling was between 0.65-0.69 g / cm ~ 3. With the increase of melt temperature, the pore size increased first and then decreased. The density of bubble pore in distal filling was higher than that in proximal end of filling. With the increase of injection speed and back pressure, the size of bubble hole at proximal end and distal end of filling had a tendency to decrease. However, the number of vesicles will increase. With the increase of SCF content, the size of foam decreased obviously, and the density of foam increased. The tensile strength of unfoamed samples remained about 30MPa under different processing conditions. The tensile strength of the foamed samples ranged from 16 to 19 MPa, compared with the unfoamed samples. The tensile strength of foamed specimens can decrease by 36% to 45%. The notched impact strength and bending strength of foamed and unfoamed specimens are maintained at 3. 5% respectively. Between KJ/m2 and 31-34.3MPa. The impact strength and bending strength of the foamed sample were generally higher than that of the unfoamed sample. Then the influence of Poe and talc powder on the foaming behavior and mechanical properties of PP composite microporous foamed material was studied. After adding POE. The viscosity of PP/POE blends increased and the melt flow rate decreased. The melt strength of PP was improved and the foaming effect of PP was improved with the increase of POE content. The average diameter of foamed sample decreased first and then increased, but the density of foam increased. When the content of POE was 15, the average diameter of foam decreased to 73.8 渭 m. The bubble density is 13.1 脳 105 / cm ~ (-3), which is 5-7 times of that of the other fractions, and the bubble pore distribution is uniform. The tensile strength and flexural strength of foamed and unfoamed samples decreased continuously. The impact strength of foamed samples reached a maximum of 18.24 MPa when the content of POE was 25. However, the impact strength of foamed samples without POE was only 3.08 MPa. for PP- / Poe / talc blends. The effect of talcum powder on the foaming effect of PP/POE blends was limited, but the overall foaming effect was still better than that of pure PPP.When the talc content was 10, the average diameter of the foam pore was 142.7 渭 m. The bubble density is 1.33 脳 10 ~ 5 / cm ~ (-3), and the morphology of foam is better than that of other components. The tensile strength of foamed sample reaches the maximum value of 17.5 MPA, which increases with the content of talc powder. The flexural strength of foamed and unfoamed blends increased to 33.57 MPA and 34.44 MPA, respectively, while the impact strength decreased continuously. But it is still higher than the impact strength of pure PP foamed sample.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ325.14

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