發(fā)布時(shí)間：2018-04-19 19:43

  本文選題：RAFT乳液聚合 + 大分子RAFT結(jié)構(gòu)��； 參考：《浙江大學(xué)》2015年博士論文

【摘要】：苯乙烯-丁二烯-丙烯腈(ABS)樹脂作為五大通用塑料之一,兼有聚丁二烯的韌性和抗沖擊性,聚丙烯腈的耐熱性和化學(xué)穩(wěn)定性以及聚苯乙烯的剛性、光澤性和加工性,得到廣泛應(yīng)用。在此基礎(chǔ)上發(fā)展起來的丙烯腈-苯乙烯-丙烯酸酯(ASA)樹脂,進(jìn)一步改善了ABS樹脂的熱氧化穩(wěn)定性、光氧化穩(wěn)定性和耐化學(xué)性,也逐漸成為一種重要的塑料材料。ABS和ASA的制備過程相似,但由于采用的是傳統(tǒng)自由基聚合方法,橡膠相為接枝共聚或輕度交聯(lián)結(jié)構(gòu),無法精確調(diào)控聚合物的分子鏈結(jié)構(gòu)。本文采用新近發(fā)展的RAFT乳液聚合的方法,以雙親性聚丙烯酸-b-聚苯乙烯大分子RAFT試劑(AA-b-S-RAFT)作為乳化劑和調(diào)控劑,制備基于嵌段共聚物的ABS和ASA韌性塑料(嵌段型ABS和ASA韌性塑料)。系統(tǒng)研究苯乙烯(S)及苯乙烯／丙烯腈(AN)的RAFT乳液(共)聚合過程、嵌段型ABS和ASA韌性塑料的制備技術(shù),探討了聚合物分子鏈結(jié)構(gòu)對(duì)材料相形態(tài)和機(jī)械性能的影響。具體的研究?jī)?nèi)容和結(jié)果如下：1)研究AA-b-S-RAFT的結(jié)構(gòu)對(duì)苯乙烯乳液聚合的影響,結(jié)果發(fā)現(xiàn)乳膠粒徑和乳膠粒數(shù)受丙烯酸鏈段長(zhǎng)度的影響較大而阻聚期則受苯乙烯鏈段的長(zhǎng)度影響較大。調(diào)節(jié)AA-b-S-RAFT的結(jié)構(gòu)使其親水親油平衡值(HLB)為13-20時(shí),聚合過程的可控性較好,聚合物分子量符合理論設(shè)計(jì)值,分子量分布較窄,且乳液穩(wěn)定性好。AA-b-S-RAFT的HLB值過低,則乳液穩(wěn)定性變差且最終產(chǎn)物的PDI較高；AA-b-S-RAFT的HLB值過高,則大分子RAFT試劑受引發(fā)劑過硫酸鉀(KPS)的氧化作用影響較大,聚合物分子量明顯高于理論設(shè)計(jì)值且產(chǎn)物的PDI較高。將引發(fā)劑KPS替換為偶氮二異氰基戊酸(V501),聚合物分子量與理論設(shè)計(jì)值相符很好但PDI較高(1.4)。在理論設(shè)計(jì)分子量一致的情況下,通過改變AA-b-S-RAFT的結(jié)構(gòu),乳膠粒徑可在80 nm-172 nm間調(diào)控。當(dāng)大分子RAFT的結(jié)構(gòu)為AA20-b-S5-RAFT,體系阻聚期較短,聚合速率快,最終轉(zhuǎn)化率高,聚合物分子量與理論設(shè)計(jì)值相符性較好,分子量分布窄(PDI=1.27),乳液穩(wěn)定性好。2)以AA20-b-S5-RAFT為乳化劑和調(diào)控劑進(jìn)行S和AN的RAFT乳液共聚合研究,結(jié)果發(fā)現(xiàn)共聚反應(yīng)無阻聚期,且體系乳膠粒數(shù)受RAFT試劑濃度的改變影響很小。共聚過程可控性好,共聚物分子量隨轉(zhuǎn)化率線性增長(zhǎng)且PDI低,但在高轉(zhuǎn)化率下因凝膠效應(yīng)的影響PDI急劇上升。凝膠效應(yīng)的程度與SAN共聚物的理論分子量和組成密切相關(guān)。對(duì)于恒比點(diǎn)共聚(質(zhì)量比m(S):m(AN)=3：1)的體系,通過在成核期結(jié)束后將聚合溫度從70℃升至90℃可有效消除凝膠效應(yīng)的影響,聚合終產(chǎn)物PDI僅為1.20左右。但隨著AN含量的增加,凝膠效應(yīng)越來越顯著,即使升溫也無法完全消除,同時(shí)AN含量的增加也使乳液的穩(wěn)定性降低。3)利用RAF T乳液聚合技術(shù),可控制備了SAN基體材料、系列SAN/PB嵌段共聚物、系列SAN/PBA嵌段共聚物,通過共混、注塑,制備嵌段型ABS和ASA韌性樹脂,并研究聚合物分子結(jié)構(gòu)與相形態(tài)和機(jī)械性能之間的關(guān)系,發(fā)現(xiàn)：a)采用乳液共混技術(shù)可制備出橡膠相粒子分散很好的嵌段型ABS和ASA韌性樹脂,橡膠相粒子均勻分散是獲得較好增韌效果的前提。相比于兩嵌段共聚物,以三嵌段共聚物作為橡膠相的材料,在不損失模量和強(qiáng)度的條件下,斷裂伸長(zhǎng)率和拉伸斷裂韌性顯著提高,但缺口沖擊強(qiáng)度降低。b)對(duì)比機(jī)械共混和乳液共混制備的嵌段型ASA材料,后者的拉伸性能(模量、強(qiáng)度、斷裂伸長(zhǎng)率和斷裂韌性)遠(yuǎn)好于前者,但缺口沖擊強(qiáng)度較差。將嵌段共聚物中的PBA段交聯(lián)可大幅提高機(jī)械共混體系的拉伸性能。c)三嵌段共聚物的嵌段型ASA材料,彎曲模量與共混制備的嵌段型ASA材料相比基本不變,但彎曲強(qiáng)度顯著提高。d)以理論分子量為60 kg/mol的SAN共聚物為基體相,橡膠含量為20%,可制備機(jī)械性能較為優(yōu)良的嵌段型ABS和ASA韌性樹脂。具體為：以SAN358-b-B4437兩嵌段共聚物為橡膠相,乳液共混制備的嵌段型ABS材料,其彈性模量、屈服強(qiáng)度、拉伸強(qiáng)度、斷裂伸長(zhǎng)率、拉伸斷裂韌性、彎曲模量、彎曲強(qiáng)度、缺口沖擊強(qiáng)度和維卡軟化點(diǎn)溫度分別可達(dá)2100 MPa.48 MPa.33 MPa 30%、12.77 MJ·m-3、2270 MPa、77.7 MPa、28.38 KJ·m-2和99.5℃；以SAN358-b-CrBA936-b-SAN358三嵌段共聚物為橡膠相,機(jī)械共混制得嵌段型ASA材料,其彈性模量、屈服強(qiáng)度、拉伸強(qiáng)度、斷裂伸長(zhǎng)率、拉伸斷裂韌性、彎曲模量、彎曲強(qiáng)度、缺口沖擊強(qiáng)度和維卡軟化點(diǎn)溫度分別可達(dá)2140 MPa、48 MPa、43 MPa、61%、27.34 MJ·m-3、2160 MPa、74.0 MPa、7.84 KJ·m-2、和96.9℃。
[Abstract]:Styrene butadiene acrylonitrile (ABS) resin is one of the five major general plastics. It also has the toughness and impact resistance of polybutadiene, the heat resistance and chemical stability of polyacrylonitrile, the rigidity, luster and processability of polystyrene. Based on this, the acrylonitrile styrene acrylate (ASA) resin has been developed. The thermal oxidation stability, photooxidation stability and chemical resistance of ABS resin are further improved, and the preparation of an important plastic material is similar to that of.ABS and ASA. However, because of the traditional free radical polymerization, the rubber phase is graft copolymerization or slightly crosslinked structure, which can not accurately regulate the molecular chain structure of the polymer. In this paper, a newly developed RAFT emulsion polymerization method was used to prepare ABS and ASA ductile plastics (ABS and ASA ductile plastics) based on block copolymers, using -b- polystyrene macromolecule RAFT reagent (AA-b-S-RAFT) as a emulsifier and regulator. The RAFT emulsion of styrene (S) and styrene / acrylonitrile (AN) was systematically studied. The process of liquid (common) polymerization, the preparation of block type ABS and ASA ductile plastics, the influence of polymer molecular chain structure on the phase morphology and mechanical properties of the materials is discussed. The specific contents and results are as follows: 1) the effect of the structure of AA-b-S-RAFT on the emulsion polymerization of styrene is studied. The results show that the size of latex particles and the number of latex particles are chain acrylic. When the structure of AA-b-S-RAFT is 13-20, the polymerization process has a better controllability, the molecular weight of the polymer is in accordance with the theoretical design value, the molecular weight distribution is narrow, and the HLB value of the emulsion has a good stability and the HLB value of.AA-b-S-RAFT is too low. The stability of the liquid is worse and the PDI of the final product is higher; the HLB value of the AA-b-S-RAFT is too high, then the large molecular RAFT reagent is influenced by the oxidation of potassium persulfate (KPS), the molecular weight of the polymer is obviously higher than the theoretical design value and the PDI of the product is higher. The initiator KPS is replaced by the azo two ISO cyanyl valerate (V501), the molecular weight of the polymer and the molecular weight of the polymer The theoretical design values are good, but the PDI is higher (1.4). In the case of the uniform molecular weight of the theoretical design, by changing the structure of AA-b-S-RAFT, the size of latex particles can be controlled between 80 nm-172 and nm. When the structure of the macromolecule RAFT is AA20-b-S5-RAFT, the polymerization period is shorter, the rate of polymerization is faster, the final conversion rate is high, the molecular weight of the polymer and the theoretical design value are high. The consistency is good, the distribution of molecular weight is narrow (PDI=1.27) and the stability of emulsion is good.2). The copolymerization of RAFT emulsion with AA20-b-S5-RAFT as emulsifier and regulator is carried out by RAFT emulsion copolymerization. The results show that the copolymerization reaction has no hindrance period, and the number of latex particles in the system is little influenced by the change of RAFT reagent concentration. The copolymerization process has good controllability and the molecular weight of the copolymer is changed with the transformation. A linear increase in rate and low PDI, but a sharp rise in the effect of the gel effect on the PDI. The degree of the gel effect is closely related to the theoretical molecular weight and composition of the SAN copolymer. For the system of constant specific point copolymerization (mass ratio m (S), m (AN) =3:1), the polymerization temperature can be effectively eliminated by raising the polymerization temperature from 70 to 90 degrees centigrade after the completion of the nucleation period. With the effect of glue effect, the final product PDI of the polymerization is only about 1.20. But with the increase of AN content, the gel effect is becoming more and more obvious, and the stability of the emulsion can not be completely eliminated, while the increase of AN content also reduces the stability of the emulsion.3). Using RAF T emulsion polymerization technology, the SAN matrix material, a series of SAN/PB block copolymers and a series of SAN/P can be controlled. BA block copolymer, through blending, injection molding, preparation of block type ABS and ASA ductile resin, and studying the relationship between the molecular structure of the polymer and the phase morphology and mechanical properties. It is found that the emulsion blending technology can be used to prepare the block type ABS and ASA ductile resin with good dispersion of the rubber particles, and the uniform dispersion of the rubber particles is better. The precondition of toughening effect is compared with the two block copolymer, with three block copolymer as the rubber phase material, the elongation at break and tensile fracture toughness are significantly increased without loss modulus and strength, but the notch impact strength decreases by.B). The tensile properties of the ASA materials are compared with the Mechanical Co mixing and emulsion co mixing. The modulus, strength, breaking elongation and fracture toughness are better than the former, but the notch impact strength is poor. The PBA segment crosslinking in the block copolymer can greatly improve the tensile properties of the mechanical blending system.C) the block type ASA material of the three block copolymer, and the flexural modulus is basically the same as the block type ASA material prepared by the blend, but the bending strength is not constant. The SAN copolymer with a theoretical molecular weight of 60 kg/mol was used as the matrix phase and the rubber content was 20%. The block type ABS and the ASA ductile resin with better mechanical properties were prepared, and the block type ABS materials were prepared with SAN358-b-B4437 two block copolymer as rubber phase and emulsion blend, and their modulus of elasticity, yield strength and tensile strength were strong. Degree, elongation at break, tensile fracture toughness, flexural modulus, bending strength, notch impact strength and VEKA softening point temperature can reach 2100 MPa.48 MPa.33 MPa 30%, 12.77 MJ. M-32270 MPa, 77.7 MPa, 28.38 KJ. M-2 and 99.5 centigrade, and SAN358-b-CrBA936-b-SAN358 three block copolymer as rubber phase, and mechanical blending to make block type ASA material The modulus of elasticity, yield strength, tensile strength, elongation at break, tensile fracture toughness, flexural modulus, bending strength, notch impact strength and VEKA softening point temperature can reach 2140 MPa, 48 MPa, 43 MPa, 61%, 27.34 MJ. M-32160 MPa, 74 MPa, 7.84 KJ. M-2, and 96.9 degrees C, respectively.

【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ317

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本文編號(hào)：1774453