The properties of the blends which consist of various rubber (SBR, BR, IR, IIR) and polyethylene (which are classed by the pressure of polymerization reaction such as High-pressure, Medium-pressure and Low-pressure) were studied. It was found that (1) polyethylenes are usefull as low-density reinforcing agent for rubbers, and the classification of reinforcing effect is as follows, Low-pressure>Medium-pressure>High-pressure, (2) the combination of IIR and polyethylene of all blends is of the most value to industrial use.

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The properties of the peroxide-cure vulcanizates of SBR/polyethylene blends were studied.
Peroxide-cure system was compared with sulfur-cure system and combination cure system of peroxide and sulfur.
It was found that (1) the linear relation is observed between the blend ratios of SBR/polyethylene and the properties of blends, (2) sulfur-cure is more effective for SBR-rich blends than peroxide-cure, while peroxide-cure is more effective for polyethylene-rich blends (3) and obviously polyethylene is cross-linked by Peroxide-cure.

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Viscoelasticities of polybutadiene (PB), NR, SBR and their blends (50/50) were measured by VIBRON-II manufactured by Toyo Measuring Instrument. Dilatometry was also applied for the investigation of their crystallinities.
The following results were obtained.
(1) Crystallinity is observed with cured high cis PB, but the temperature of crystallinity is low as compared with that of raw polymer. Difference of Cis-content results in the difference of the temperature of crystallinity. In the case of low cis PB, crystallinity is never observed in both raw and cured polymers.
(2) Blending of NR with either of PB produces a heterogeneous mixture, but low cis PB excels high cis PB in the compatibility. In the case of high cis PB, crystallinity is observed even in the blending with NR.
(3) Blending of SBR with each of PB produces a homogeneous mixture except for one of high cis PB and crystallinity is almost never observed in the case of high cis PB.

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Plasticized vinyl polymers (PMMA and PVC) were masticated by hot rolls in order to study the effects of distance and friction ratio of rolls on the shear degradation of these polymers.
In general, the rate of degradation could be expressed as follows :
-dp/dt=k (P_t-P_l) ⁿ
where n is dependent on polymers.
For PVC, it was expressed as follows :
-dp/dt=k (P_t-P_l)
The rate of degradation of PMMA by roll milling could be approximated by -dp/dt=k (P_t-P_l) ²
where P_t : DP at time t, P_l : final DP, k : constant.
It was found that PMMA was badly ruptured with a reduced distance of rolls, and that the extent of degradation was inversely proportional to the roll distance.
Effect of roll friction ratio on rupture is not so great as that of roll distance.

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The exchange reactions have been studied in xylene solution. Used accelerators in this experiments were as follows, tetramethyl thiuram disulfide (TT)
tetramethyl thiuram monosulfide (TS)
2-benzothiazolyl disulfide (DM)
The reactions of bis type accelerators (TT, DM) have induction periods in each case, and inflection points shift to earlier stage at higher temperature. Considering from these facts, the reaction has two steps occuring subsequently. In the first step, the accelerator turns into radicals by dissociati on of S-S bond. In the next step, isotopic sulfur (S^*₈ ring structure) reacts with the radical at the point of C^δ+ =S^δ- bond and then S^* atom exchanges with that of radical.
S-S bond in TT dissociates easier than that of DM. The activation energies of the second steps in TT and DM are 30 Kcal/mol and 23.₄ Kcal/mol respectively.
In the case of TS, the radicals are formed by dissociation of C-S bond. In early stage of the reaction, sulfur in TS exchanges with isotopic sulfur, but TT is formed by the addition of isotopic sulfur atom to. TS in proceeding stage.

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